Surface Properties

The aim of this study was to evaluate the influence of the poly-L-lactic acid (PLLA)-based scaffold's pore size on the proliferation and differentiation of dental pulp stem cells (DPSCs). The scaffolds were prepared in pulp chambers of 1-mm-thick tooth slices from third molars using salt crystals (150-250 µm or 251-450 µm) as porogen. DPSC (1x105 cells) were seeded in the scaffolds with different pore sizes, and cultured in 24-well plates. The cell proliferation was evaluated using the WST-1 assay after 3-21 days. Furthermore, RT-PCR was used to assess the differentiation of the DPSCs into odontoblasts, using markers of odontoblastic differentiation (DSPP, DSP-1 and MEPE). RNA from human odontoblasts was used as control. Cell proliferation rate was similar in both scaffolds except at the 14th day period, in which the cells seeded in the scaffolds with larger pores showed higher proliferation (p<0.05). After 21 days DPSCs seeded in both evaluated scaffolds were able of express...

Made from a variety of natural sources, Nano Crystalline Cellulose (NCC) is a unique renewable nanomaterial with a wide range of applications due to its high stiffness and strength, low weight, biodegradability, and environmental benefits. Because of its special inherent qualities, NCC is one of the most renewable materials to be addressed by nanomaterials. The origins, manufacture, characteristics, and applications of nanomaterials, including NCC and nanofibers, have been extensively studied by a large number of researchers throughout the years. Strong chemical reactivity, crystallinity, strength and stiffness, biocompatibility, biodegradability, shape, and nanoscale dimensions are just a few of the remarkable properties that these nanomaterials have been shown to possess in countless investigations. These characteristics enable the application of these nanoparticles in a number of fields, including medicine. Among the most traditional and popular techniques. Electrospinning is one of the earliest and most popular techniques for producing nanofibers. This method works well and can be modified to produce continuous nanofibers. NCC-based nanofibers are novel materials in the biomaterials industry. Recent studies demonstrated that electrospun nanofibers could be efficiently loaded with a wide range of drugs, such as proteins, chemotherapeutic agents, antibiotics, and analgesics with anti-inflammatory qualities. One application of NCC and nanofibers in the medical field is drug delivery. This review highlights a number of issues related to NCC nanofibers and their use in drug delivery applications, beginning with discussing the various natural polymer types used in drug delivery applications, the physicochemical and biological properties of NCC, its various applications, its significance, and its preparation techniques.

Synchrotron radiation and a CCD detector were employed to map the full width at half maximum (FWHM) of rocking curves for a synthetic (0 0 1) oriented type Ib diamond plate. The plate was sawed from a diamond grown in the high-pressure-high-temperature (HPHT) process. Maps for broadening relative to a reference point on the diamond for the (2 2 4) reflection at 12 keV are reported before and after chemical etching. Significant rocking curve narrowing over most of the diamond was found, and we conclude that the diffraction performance of (0 0 1) oriented type Ib diamonds can be significantly improved over a large area by chemical etching. Stripes in the map before etching corresponded to grooves formed in the process of sawing the plate out of the as-grown stone. The FWHM map did not correlate with the surface height profile measured after ∼10 µm were removed from the surface by etching.

Excess enthalpies, vapor-liquid equilibrium data and surface tensions of the highly non-ideal associated mixtures formed by methanol or ethanol and propanal have been measured in the temperature range of 288.15-318.15 K. These mixtures show negative deviations from ideality, including a negative azeotrope for the methanol-propanal system in the methanol-rich region. The values for the excess enthalpies are very exothermic and become less negative as temperature increases. Methanol-propanal mixtures exhibit minima of approximately -8.6 and -8.0 kJ mol-~, at a mole fraction close to 0.5 and 298.15 and 318.15 K, respectively. The ethanol-propanal system exhibits minima of approximately -7.2 and -5.0 kJ mol-l at 298.15 and 318.15 K, respectively. The surface tension has been measured at 298.15 K. Values for the relative surface adsorption calculated from the surface tension and the chemical potentials indicate that the surface is significantly enriched in propanal for mixtures rich in methanol. The calculated values for the concentration-concentration correlation function are lower than those corresponding to an ideal mixture and exhibit a minimum in the middle of the concentration range. A complex composition dependence of the concentration profiles can be inferred. The Lattice-Fluid Associated Solution, the UNIQUAC Associated Solution and the Extended Real Associated Solution models have been used to describe the bulk properties of the alcohol-propanal mixtures.

Purpose: The purpose of this study was to evaluate the level of contaminants on, as well as the quality of, reprocessed shaver blades. Methods: We assessed 7 new shaver blades and 27 shaver blades that bad been reprocessed with mechanical c1eaning, functional testing, and sterilization with ethylene oxide. A spectrophotometer measured the amount of nuc1eic acid and protein. The blade quality was assessed by photographing the blades with magnification and determining the percentage of damage present on each blade. A subset of shaver blades were then used to cut meniscal tissue, and the cut surface was measured for smoothness by image proeessing and automated laser scanning cytometry. In evaluation of the meniscus, for the subset of shavers, an image proeessing valne of l indicates a smooth, straight line, and values lower than 1 reflect deviations in the cut surface (the c1oser the valne is to 1, the smoother the surface). Laser scanning cytometry values indicate the percentage of irregularities in the cut surface (the lower the valne is, the smoother the surface). Results: Of the 27 reprocessed shaver blades, 13 (48%) bad detectable 1evels of protein and 17 (63%) bad detectable levels of nuc1eicacid. On the reprocessed shaver blades, protein levels ranged from 2.43 J.Lgto 60 J.Lgand nucleic !leid levels ranged from 0.40 J.Lgto 3.5 J.Lg. No new shaver blade bad contaminants. Twenty reprocessed shaver blades bad been manufactured with teeth and could be evaluated for visible damage. Ofthese, 10 bad 1% to 25% damage, 5 bad 26% to 50% damage, 3 bad 51% to 75% damage, and 2 had.76% to 100% damage. The new blades bad no visible damage. Image proeessing revealed smoothness.of the surface cut with new shaver blades, yielding valu~s of 1 :t 0.12, whereas the values for reprocessed shaver blades ranged from 0.62 :t 0.02 to 1 :t 0.07. Laser scanning cytometry values rangedfrom 3.3% to 7.1% for the new blades as compared with 5.8% to 20.0% for the reprocessed blades. Conclusions: Of the reprocessed shaver blades, 48% bad detectable levels of protein and 63% bad detectable levels of nuc1eic acid. All of the reprocessed blades visually evaluated showe~same level of damage or wear, whereas no new blade bad such damage. In addition, menisci 90:twith reprocessed shavers showed rougher edges than didIIlenisci cut with new shavers. ClinicalRelevance: To make an informed decision regar~ingth~lise of reprocessed shaver blades, surg~ons will want to know the level of contarnination on, andth~quality of, reprocessed shaver blades.

The purpose of this study was to compare chondroplasty performed with an ExoJet high-pressure fluid-driven burr (Mitek, Norwood, MA), a mechanical shaver, and a bipolar radiofrequency (RF) wand on articular cartilage-covered condyles taken from sheep cadavers that were induced to have an osteoarthritic-like condition, and corresponding healthy control tissue. Type of Study: Experimental designed animal cadaveric, biochemical, and histologic study. Methods: Sheep condyles were used as a source of articular cartilage. Femurs were extracted approximately 1 hour postmortem and a transverse section of the condyles was made. Half of the samples were treated to induce an osteoarthritic-like condition. The condyles were then subjected to chondroplasty performed with the ExoJet high-pressure fluid-driven burr, a mechanical shaver, and a bipolar RF wand under sterile saline solution by an experienced orthopaedic surgeon. Twenty cross-sections from each condyle were examined by confocal microscopy to measure smoothness and depth of tissue damage to the articular cartilage caused by each of the 3 instruments. Results: The ExoJet high-pressure fluid-driven burr and the bipolar RF wand left a smoother surface on the articular cartilage compared with the mechanical shaver. Additionally, the ExoJet fluid-burr caused slightly less tissue damage to the cartilage than the bipolar RF wand, both of which were less damaging than the shaver. Conclusions: Orthopaedists have multiple choices for surgical instruments used on cartilage. However, the effect on the integrity of the cartilage left remaining at the knee was previously unknown. Based on this study, a fluid-burr appears to leave the cartilage with a smaller zone of injury than does the RF wand or shaver. It also leaves the cartilage surface smoother than the shaver. During surgical procedures, minimizing cartilage breakdown and smooth remaining surfaces are desired because they minimize the vulnerable tissue to further destruction. A fluid burr leaves cartilage with less injury and with a smoother surface than do more traditional surgical instruments. Clinical Relevance: This information should help surgeons in their selection of currently available surgical instruments and should aid engineers in the design of future instruments that function to modify articular cartilage.

Objectives: This study investigated the immediate and sustained effect of sodium trimetaphosphate (TMP) and sodium hexametaphosphate (HMP) associated or not with fluoride (F) on hydroxyapatite (HA) dissolution using an erosion-like model, considering the salivary coating formation. Design: Baseline dissolution rates were determined for HA discs using a pH-stat system. In the first set of experiments, HA discs were treated with 1100 µg F/mL, 1% or 8% of HMP, 1% or 8% of TMP and 1100 µg F/mL associated with 1% or 8% of HMP or TMP, totaling 9 groups (n=8). In a second phase, HA discs were kept in pooled human saliva at 37º C for 2h before treatment with deionised water and 1100 µg F/mL associated with 1% or 8% of HMP or TMP, totaling 5 groups (n=8). The post-treatment dissolution rate was determined from three consecutive 30-min assays. Data were analysed using 2 and 3-way ANOVA followed by Fisher and Holm-Sidak methods, respectively (α=0.05). Results: All test solutions promoted reduction in HA dissolution rate when compared to baseline control in the first post-treatment run (p<0.001). However, a synergistic effect was only observed between fluoride and 1% HMP. Moreover, the duration of inhibitory effect was greater when 8% HMP and 1 or 8% HMP associated with F were assessed (p<0.001). The presence of salivary coating led to higher protection for all groups when compared to discs without coating (p<0.001). The reduction of HA dissolution rate, as well as the duration of this effect were influenced by fluoride, type and concentration of phosphate salt and the presence of a salivary coating.

Many bioprocesses depend on the effective formation of a biofilm on a solid support. In the present study, three different surface treatments (sandblasting, pure-O 2 plasma, and He-O 2 plasma treatments) were conducted on polypropylene (PP) Pall rings used as a support in biotrickling filters for air pollution control. The intent was to modify the ring surface and/or electrochemical properties in order to possibly improve cell adhesion, wetting properties, and possibly reduce the start-up time and increase the performance of the biotrickling filters. The surface treatments were found to generally increase the hydrophilicity and the zeta potential of the surfaces. However, the startup and performance of lab-scale biotrickling filters packed with treated Pall rings were not significantly different than the control with untreated rings. Cell and colloid deposition experiments conducted in flow cells showed that the treated surfaces and the hydrodynamic conditions were not favorable for cell deposition indicating that there could be significant opportunities for improving packings used in environmental bioprocess applications.

Tactile explorations with the fingertips provide information regarding the physical properties of surfaces and their relative pleasantness. Previously, we performed an investigation in the active touch domain and linked several surface properties (i.e. frictional force fluctuations and net friction) with their pleasantness levels. The aim of the present study was to investigate physical factors being important for pleasantness perception during passive fingertip stimulation. Specifically we were interested to see whether factors, such as surfaces' topographies or their frictional characteristics could influence pleasantness. Furthermore, we ascertained how the stimulus pleasantness level was impacted by (i) the normal force of stimulus application (F ) and (ii) the stimulus temperature (T ). 23h Archived Tweets

Background: The profiles of lipids in normal and cancerous tissues may differ revealing information about cancer development and progression. Lipids being surface active, changes in lipid profiles can manifest as altered surface activity profiles. Langmuir monolayers offer a convenient model for evaluating surface activity of biological membranes. The aims of this study were to quantify phospholipids and their effects on surface activity of normal and cancerous human cervical tissues as well as to evaluate the role of phosphatidylcholine (PC) and sphingomyelin (SM) in cervical cancer using Langmuir monolayers. Methods and Materials: Lipid quantification was done using thin layer chromatography and phosphorus assay. Surface activity was evaluated using Langmuir monolayers. Monolayers were formed on the surface of deionized water by spreading tissue organic phase corresponding to 1 mg of tissue and studying their surface pressure-area isotherms at body temperature. The PC and SM contents of cancerous human cervical tissues were higher than those of the normal human cervical tissues. Role of PC and SM were evaluated by adding varying amounts of these lipids to normal cervical pooled organic phase. Statistical analysis: Student's t-test (p < 0.05) and one-way analysis of variance (ANOVA) was used. Results: Our results reveals that the phosphatidylglycerol level in cancerous cervical tissue was nearly five folds higher than that in normal cervical tissue. Also PC and sphingomyelin SM were found to be the major phospholipid components in cancerous and normal cervical tissues respectively. The addition of either 1.5 µg DPPC or 0.5 µg SM /mg of tissue to the normal organic phase changed its surface activity profile to that of the cancerous tissues. Statistically significant surface activity parameters showed that PC and SM have remarkable roles in shifting the normal cervical lipophilic surface activity towards that of cancerous lipophilic component. The Langmuir monolayer technique was sensitive to detect changes in tensiometric profiles of cervical cancers and these could be modulated by alterations in phosphatidylcholine and sphingomyelin levels. Therapeutic strategies may be designed to modulate these tensiometric profiles and lipid constituents of cancerous tissues.

One way of controlling friction and associated energy losses is to engineer a deterministic structural pattern on the surface of the rubbing parts (i.e., texture engineering). Custom texturing enhances the quality of lubrication, reduces friction, and allows the use of lubricants of lower viscosity. To date, a standardized procedure to generate deterministic texture constructs is virtually non-existent. Many engineers, therefore, study natural species to explore surface construction and to probe the role surface topography assumes in friction control. Snakes offer rich examples of surfaces where topological features allow the optimization and control of frictional behavior. In this paper, we investigate the frictional behavior of a constrictor type reptile, Python regius. The study employed a specially designed tribo-acoustic probe capable of measuring the coefficient of friction and detecting the acoustical behavior of the skin in vivo. The results confirm the anisotropy of the frictional response of snakeskin. The coefficient of friction depends on the direction of sliding: the value in forward motion is lower than that in the converse direction. Detailed analysis of the surface metrological feature reveal that tuning frictional response in snakes originates from the hierarchical nature of surface topology combined to the profile asymmetry of surface micro-features, and the variation of the curvature of the contacting scales at different body regions. Such a combination affords the reptile the ability to optimize the frictional response.

The template-stripping method can yield smooth patterned films without surface contamination. However, the process is typically limited to coinage metals such as silver and gold because other materials cannot be readily stripped from silicon templates due to strong adhesion. Herein, we report a more general template-stripping method that is applicable to a larger variety of materials, including refractory metals, semiconductors, and oxides. To address the adhesion issue, we introduce a thin gold layer between the template and the deposited materials. After peeling off the combined film from the template, the gold layer can be selectively removed via wet etching to reveal a smooth patterned structure of the desired material. Further, we demonstrate template-stripped multilayer structures that have potential applications for photovoltaics and solar absorbers. An entire patterned device, which can include a transparent conductor, semiconductor absorber, and back contact, can be fabricated. Since our approach can also produce many copies of the patterned structure with high fidelity by reusing the template, a low-cost and high-throughput process in micro-and nanofabrication is provided that is useful for electronics, plasmonics, and nanophotonics.

We report a computational study on the spontaneous self-assembly of spherical particles into two-dimensional crystals. The experimental observation of such structures stabilized by spherical objects appeared paradoxical so far. We implement patchy interactions with the patches point-symmetrically (icosahedral and cubic) arranged on the surface of the particle. In these conditions, preference for self-assembly into sheet-like structures is observed. We explain our findings in terms of the inherent symmetry of the patches and the competition between binding energy and vibrational entropy. The simulation results explain why hollow spherical shells observed in some Keplerate-type polyoxometalates (POM) appear. Our results also provide an explanation for the experimentally observed layer-by-layer growth of apoferritin - a quasi-spherical protein.

Controlling the cellular microenvironment can be used to direct the cellular organization, thereby improving the function of synthetic tissues in biosensing, biorobotics, and regenerative medicine. In this study, we were inspired by the microstructure and biological properties of the extracellular matrix to develop freestanding ultrathin polymeric films (referred as "nanomembranes") that were flexible, cell adhesive, and had a morphologically tailorable surface. The resulting nanomembranes were exploited as flexible substrates on which cell-adhesive micropatterns were generated to align C2C12 skeletal myoblasts and embedded fibril carbon nanotubes enhanced the cellular elongation and differentiation. Functional nanomembranes with tunable morphology and mechanical properties hold great promise in studying cell-substrate interactions and in fabricating biomimetic constructs toward flexible biodevices.

Nanotechnology has opened a new horizon of research in various fields including applied physics, chemistry, electronics, optics, robotics, biotechnology and medicine. In the biomedical field, nanomaterials have shown remarkable potential as theranostic agents. Materials which are considered inert are often used in nanomedicine owning to their nontoxic profile. At nanoscale, these inert materials have shown unique properties that differ from bulk and dissolved counterparts. In the case of metals, this unique behavior not only imparts paramount advantages but also confers toxicity due to their unwanted interaction with different cellular processes. In the literature, the toxicity of nanoparticles made from inert materials has been investigated and many of these have revealed toxic potential under specific conditions. The surge to understand underlying mechanism of toxicity has increased and different means have been employed to overcome toxicity problems associated with these agents. ...

A protocol for nanostructuring and electropolymerization of a hybrid semiconductor polycarbazole-titanium oxide ultrathin film is described. Ultrathin (<100 nm) films based on polycarbazole precursor polyelectrolytes and titanium oxide (TiO x ) have been fabricated by combining the layer-by-layer (LbL) and surface sol-gel layering techniques. Film growth was followed and confirmed through UV-vis spectroscopy, ellipsometry and quartz crystal microbalance with dissipation (QCM-D). Subsequent anodic electrochemical oxidation of the carbazole pendant units afforded a conjugated polymer network (CPN) film within intercalating TiO x layers of cross-linked and π-conjugated carbazole units. Cyclic voltammetry (CV), UV-vis, and fluorescence spectroscopy measurements confirmed this process. The LbL-driven polyelectrolyte deposition process resulted in a quantified electrochemical response, proportional to the number of layers, while the TiO x acted as a dielectric spacer limiting electron transfer kinetics and attenuating energy transfer in fluorescence. Electro-optical properties were compared with other polycarbazole thin film materials with respect to bandgap energy (E g ). The straightforward protocol in film nanostructuring and barrier/dielectric properties of the inorganic oxide slab (denoted here as, TiO x ) should enable applications in organic light-emitting diodes (OLEDs), dielectric mirrors, planar waveguides, and photovoltaic devices for these hybrid ultrathin films.

Introduction: This in vitro study aims to evaluate the coronal and apical sealing ability of gutta-percha (GP) root filling used with either mineral trioxide aggregate (MTA), new endodontic cement (NEC) or AH26 as filler/sealers. Materials and methods: Forty eight single-rooted extracted teeth were selected, decoronated and then instrumented. Samples were randomly divided into three experimental (n=12) and two control groups (n=6). In group 1, root canals were filled using lateral condensation technique (L); while single cone technique (S) was used for groups 2 and 3. AH26, MTA and NEC were the root canal sealer/fillers in groups 1, 2 and 3, respectively. Samples were immersed in 1% methylene-blue dye and then independently centrifuged apically and coronally. The roots were split longitudinally and linear extent of dye penetration was measured with a stereomicroscope from apical and coronal directions. Data were analyzed using One-way ANOVA and T-test. Results: No statistical differences in mean apical dye penetration between groups LGP/AH26, SGP/MTA and SGP/NEC were found; SGP/NEC group showed significantly less coronal dye penetration (P<0.001). Conclusion: Considering the limitations of this in vitro study, it was concluded that the simple single cone technique with NEC can provide favorable coronal and apical seal.

Full field optical coherence tomography (FF-OCT) using a conventional LED light source and a CMOS camera has been developed for characterising coatings on small pellet samples. A set of en-face images covering an area of 700μm x 700μm were taken over a depth range of 166 μm. The three-dimensional structural information, such as the coating thickness and uniformity, was subsequently obtained by analysis of the recorded en-face images. Drug loaded pharmaceutical sustained release pellets with two coating layers and of a sub-millimetre diameter were studied to demonstrate the usefulness of the developed system. We have shown that both coatings can be clearly resolved and the thickness was determined to be 40 μm and 50 μm for the outer and inner coating layers, respectively. It was also found that the outer coating layer is relatively uniform whilst the inner coating layer has many particle-like features. X-ray Computed Microtomography (XμCT) measurements carried out on the same pellet sample confirmed all these findings. The presented FF-OCT approach is inexpensive and has better spatial resolution compared to other non-destructive analysis techniques such as terahertz pulsed imaging, and is thus considered advantageous for the quantitative analysis of thin coatings on small pellet samples.

Glioblastoma multiforme (GBM) remains the deadliest brain tumor in adults. GBM tumors are also notorious for drug and radiation resistance. To inhibit GBMs more effectively, polymalic acid-based blood-brain barrier crossing nanobioconjugates were synthesized that are delivered to the cytoplasm of cancer cells and specifically inhibit the master regulator serine/threonine protein kinase CK2 and the wild-type/mutated epidermal growth factor receptor (EGFR/EGFRvIII), which are overexpressed in gliomas according to The Cancer Genome Atlas (TCGA) GBM database. Two xenogeneic mouse models bearing intracranial human GBMs from cell lines LN229 and U87MG that expressed both CK2 and EGFR at different levels were used. Simultaneous knockdown of CK2α and EGFR/EGFRvIII suppressed their downstream prosurvival signaling. Treatment also markedly reduced the expression of programmed death-ligand 1 (PD-L1), a negative regulator of cytotoxic lymphocytes. Downregulation of CK2 and EGFR also caused deac...

A new mechanism of gene expression inhibition has been discovered as RNA interference, in which the ability of double-stranded RNA to stimulate specific degradation of an mRNA target with a complementary sequence to one of the double-stranded RNA strands. Water-soluble carbosilane dendrimers containing ammonium or amine groups at their periphery are biocompatible molecules that may be good candidates as non-viral carriers of small interfering RNA. In studying the formation of complex between anti-HIV siRNA siGAG1 and carbosilane dendrimers NN8 and NN16 by circular dichroism, fluorescence, and zetapotential, the size of nanoparticles formed has been estimated by dynamic light scattering. At a charge ratio of 1:3-4 (siGAG1:dendrimer), the dendriplexes formed were in the size range of 250-350 nm.

The present generation of mechanical heart-valves prostheses offers significantly improved blood compatibility, combined with appropriate physical and mechanical properties and durability; however, thromboembolism persists as a crucial clinical complication because of the key role played by adsorbed plasma proteins and adherent platelets in determining hemocompatibility. In the present work human plasma protein adsorption and platelet adhesion and activation were evaluated on four materials, selected according to their different physico-chemical and morphological properties: pyrolytic carbon (PyC), titanium alloy Ti-6Al-4V (Ti), tissue culture polystyrene (TCPS) and polystyrene sterilized by γ-irradiation (StPS). Morphological and chemical properties of surfaces were assessed by Time of Flight Secondary Ion Mass Spectrometry (Tof-SIMS), X-ray Photoemission Spectroscopy (XPS), Atomic Force Microscopy (AFM) and Contact Angle (CA) analysis, while protein adsorption and platelet adhesion and activation were evaluated by colorimetric and immunofluorescence tests and Scanning Electron Microscopy (SEM), respectively. Among the analyzed materials, PyC induced the lowest level of protein adsorption and platelet adhesion and activation. In particular, immunofluorescence analysis of fibronectin (FN), fibrinogen (FG), von Willebrand factor (vWF), Hageman factor (FXII) and albumin (ALB) showed that PyC surface was characterized by high levels of FG adsorption, low levels of FN, ALB and vWF and the absence of FXII. Finally, when analyzing the biological response as a function of surface properties, it was found that protein adhesiveness increased with increasing contact angle values. To the contrary, platelet activation related to the total amount of adherent proteins was poor while cell activation was possibly dependent on the detailed composition of the underlying protein layer. Furthermore, differences in surface roughness of the examined materials did not seem to influence the biological response in terms of platelet activation and protein adsorption.

Photodynamic inactivation (PDI) of bacteria may play a major role in facing the challenge of the ever expanding antibiotic resistances. Here we report about the direct correlation of singlet oxygen luminescence kinetics and phototoxicity in E. coli cell suspension under PDI using the widely applied cationic photosensitizer TMPyP. Through direct access to the microenvironment, the time resolved investigation of singlet oxygen luminescence plays a key role in understanding the photosensitization mechanism and inactivation pathway. Using the homemade set-up for highly sensitive time resolved singlet oxygen luminescence detection, we show that the cationic TMPyP is localized predominantly outside the bacterial cells but in their immediate vicinity prior to photodynamic inactivation. Throughout following light exposure, a clear change in singlet oxygen kinetics indicates a redistribution of photosensitizer molecules to at least one additional microenvironment. We found the signal kinetics mirrored in cell viability measurements of equally treated samples from same overnight cultures conducted in parallel: A significant drop in cell viability of the illuminated samples and stationary viability of dark controls. Thus, for the system investigated in this worka Gram-negative model bacteria and a well-known PS for its PDIsinglet oxygen kinetics correlates with phototoxicity. This finding suggests that it is well possible to evaluate PDI efficiency directly via time resolved singlet oxygen detection.

The synergistic role of platinum and silica as a way to increase the final residue of pyrolized silicone was investigated and explained, giving new interpretations. Conditions were first set to study the thermal degradation of silicones in the presence of platinum based on the simplest silicone/silica/ platinum formulation. Numerous parameters, e.g., platinum and silica content or silica surface modifications, were varied to track their influences on the final residues. A thorough DSC study, together with SEM/EDX and Pyrolysis/GC-MS analyses, led us to propose a three-stage process. The key parameter governing thermal stability and final content of the residue is the conjugated actions of immobilizing/cross-linking PDMS chains. Silica particles tether silicone chains through physical interactions, i.e., hydrogen bonding, facilitating a platinum radically catalyzed cross-linking reaction. Practical implications and possible improvements on LSR formulations are finally given.

It is now known that erbium lasers are effective in composite removal, but there is minimal information about their efficacy on recycling of ceramic brackets. This study, therefore, aimed to determine the percentage of remaining adhesive on the base and the shear bond strength of debonded ceramic brackets after being reconditioned by an Er,Cr:YSGG (erbium, chromium: yttrium-scandium-gallium-garnet) laser. Thirty premolars were divided into three groups, then bonded with mechanical retention ceramic brackets according to the bracket base conditions: (1) new brackets; (2) debonded brackets cleaned of adhesive with the Er,Cr:YSGG laser at 3.5 W; and (3) debonded brackets cleaned of adhesive with the Er,Cr:YSGG laser at 4 W. Before bonding, the percentage of remaining adhesive on the bases of reconditioned brackets was calculated by using stereomicroscopic images through an image processing software. The brackets were then tested in shear mode in a universal testing machine and the adhesive remnant index scores were determined. The percentage of remaining adhesive on the bases of brackets that were cleaned by the Er,Cr:YSGG laser at 4 W (3.1 %) was significantly lower than that of the 3.5-W laser group (5.9 %) (p00.03). No significant difference was found in bond strengths between the new and the reconditioned brackets (p=0.19). The frequency of bond failure at the enamel-adhesive interface was lower in the laser-reconditioned brackets when compared to the new brackets. The application of Er,Cr:YSGG laser was efficient in removing adhesive from bases of debonded ceramic brackets because it produced comparable bond strengths to new brackets while reducing the risk of enamel damage during debonding.

Aim: This study aimed to evaluate clinical outcomes of titanium membrane and compare these findings with clinical outcomes of e‐PTFE membrane, and to investigate the effect of bacterial contamination on both membranes with SEM during long‐term healing. Results: Sixteen titanium and sixteen e‐PTFE membranes were surgically placed adjacent to periodontally involved teeth. Seven titanium and 8 e‐PTFE membranes were exposed between 4 and 6 weeks. There were no significant difference between groups for plaque and gingival index. Probing depth and clinical attachment level (CAL) were decreased in both groups when compared with baseline; however, these differences were not statistically significant. The CAL gains between the groups were statistically different in 3rd, 6th, 9th, 12th, and 24th months (p &lt; 0.05), and the CAL gain was significantly higher in titanium membrane (p &lt; 0.05). There was significant decrease in bleeding on probing from baseline in both groups (p &lt; 0.05). Su...

We conducted an experimental study on the spontaneous formation of peptides from two parallel reactions gly-asp acid/val mixtures in aqueous media and in the presence and absence of metal oxide catalysts, specifically alumina and silica, at 85 ± 5°C under simulated early Earth drying-wetting cycles. Analytical techniques revealed the synthesis of homogeneous and heterogeneous peptides, including cyclic glycine structures, resulting from intra-and intermolecular condensation reactions. Peptide yield was influenced by thermal treatment duration and, to a lesser extent, the presence of metal oxide catalysts. Notably, the gly-val system preferred to form glycine homo-oligomers up to tetrameric levels and heteropeptides including diketopiperazine. Conversely, the gly-asp acid system displayed limited oligomerization, reaching only trimeric levels, and yielded glycyl-aspartic acid. These findings offer valuable insights into the potential mechanisms underlying protein evolution on primitive Earth.

Janus membranes with asymmetric surface wettability have been extensively utilized in various fields, including fog harvesting, because of their novel liquid transport properties. However, Janus membranes have an inherent disadvantage in terms of aerodynamic efficiency in harvesting fog because of the clogged water bridges caused by the small pore size. In the present work, we applied Janus wettability to mesh geometry with systematically varying hole sizes. For a clogged mesh with a small hole size, capillary water transport to the mesh back via the wettability gradient in the direction of fog flow helps harvest more fog by enhancing water drainage, similarly to the Janus membrane. The advantage of the capillary water transport extends to a clog-free mesh with larger hole sizes but more preferably to a Janus mesh with a superhydrophilic back, which presents the highest level of fog-harvesting yield because of the fast shedding frequency and short onset time. In contrast, a Janus mesh with a superhydrophobic front, which also has a wettability gradient along the fog flow, produces a lower fog-harvesting performance, particularly at slow fog speeds, because of the dropwise deposition of large water drops that locally disturb fog flow around a protruding water surface. On the other hand, the other type of Janus mesh with a superhydrophilic front is observed to minimize this disadvantage in the local fog flow by virtue of the filmwise deposition. It is also found that some Janus treatments can help protect mesh holes from clogging up by either forming a thin water meniscus or resisting water transport through the mesh holes.

This paper presents a new method for simultaneously retrieving aerosol and surface reflectance properties from combined airborne and ground-based direct and diffuse radiometric measurements. The method is based on the standard Aerosol Robotic Network (AERONET) method for retrieving aerosol size distribution, complex index of refraction, and single scattering albedo, but modified to retrieve aerosol properties in two layers, below and above the aircraft, and parameters on surface optical properties from combined datasets (Cloud Absorption Radiometer (CAR) and AERONET data). A key advantage of this method is the inversion of all available spectral and angular data at the same time, while accounting for the influence of noise in the inversion procedure using statistical optimization. The wide spectral (0.34-2.30 µm) and angular range (180 • ) of the CAR instrument, combined with observations from an AERONET sunphotometer, provide sufficient measurement constraints for characterizing aerosol and surface properties with minimal assumptions.

We report on the one-pot synthetic procedure of cyclen derivatives bearing three acetate groups attached on boehmite nanoparticles, the complexing capabilities of these inorganicorganic hybrid materials with rare earth cations, and the behaviour as contrast agents or fluorescence probes.

Multilayered (laminated) composites exhibit tunable mechanical behavior compared to bulk materials due to the presence of more interfaces and therefore magnesium based composites are gaining wide popularity as biodegradable materials targeted for temporary implant applications. The objective of the present work is to fabricate magnesium based lamellar metal matrix composites (MMCs) for degradable implant applications. Nano-hydroxyapatite (HA) powder was selected as the secondary phase and lamellar structured magnesium-nano-hydroxyapatite (Mg-HA) composites of 8, 10 and 15 wt. % HA were fabricated by ball milling and spark plasma sintering. It was found that, HA particles were coated on the Mg flakes after 20 h of ball milling carried out using tungsten carbide (WC) as the milling media. Spark plasma sintering of the milled powders resulted in the formation of lamellar structure of Mg with the presence of HA and magnesium oxide (MgO) at the inter-lamellar sites of the composites. Phase analysis of the milled powder by X-ray diffraction (XRD) method confirms the presence of HA and MgO along with Mg after sintering. Corrosion behavior of the composites investigated by potentiodynamic polarization tests shows a reduction in the inter-lamellar corrosion with increase in HA content and the best corrosion resistance was found for the Mg-10% HA composite. This composite also exhibits maximum Vickers hardness. The Young' modulus and fracture toughness measured by nano-indentation method were higher for the Mg-8% HA composite. The results thus suggest that lamellar structured Mg composites with 8 and 10% HA show promise for temporary degradable orthopedic implant applications because of their improved corrosion resistance and superior mechanical properties.

AZ31 magnesium alloy was coated with polycaprolactone (PCL) nano-fibrous layer using electrospinning technique so as to control degradation in physiological environment. Before coating, the alloy was treated with HNO 3 to have good adhesion between the coating and substrate. To elucidate the role of pre-treatment and coating, samples only with PCL coating as well as HNO 3 treatment only were prepared for comparison. Best coating adhesion of 4B grade by ASTM D3359 -09 tape test was observed for pre-treated samples. The effect of coating on in vitro degradation and biomineralization was studied using supersaturated simulated body fluid (SBF 5×). The weight loss and corrosion results obtained by immersion test showed that the combination of HNO 3 pre-treatment and PCL coating is very effective in controlling the degradation rate and improving bioactivity. Cytotoxicity studies using L6 cells showed that PCL coated sample has better cell adhesion and proliferation compared to uncoated samples. Nano-fibrous PCL coating combined with prior acid treatment seems to be a promising method to tailor degradation rate with enhanced bioactivity of Mg alloys.

Multilayered (laminated) composites exhibit tunable mechanical behavior compared to bulk materials due to the presence of more interfaces and therefore magnesium based composites are gaining wide popularity as biodegradable materials targeted for temporary implant applications. The objective of the present work is to fabricate magnesium based lamellar metal matrix composites (MMCs) for degradable implant applications. Nano-hydroxyapatite (HA) powder was selected as the secondary phase and lamellar structured magnesium-nano-hydroxyapatite (Mg-HA) composites of 8, 10 and 15wt% HA were fabricated by ball milling and spark plasma sintering. It was found that HA particles were coated on the Mg flakes after 20h of ball milling carried out using tungsten carbide (WC) as the milling media. Spark plasma sintering of the milled powders resulted in the formation of lamellar structure of Mg with the presence of HA and magnesium oxide (MgO) at the inter-lamellar sites of the composites. Phase an...

Glass ionomer cements (GICs) are clinically attractive filling materials often employed in the field of dentistry as restorative and luting materials. The present work aims to formulate bioactive nanocrystalline calcium deficient hydroxyapatite (nCDHA)-GIC composite cements with improved mechanical and resorption properties of the set cement than GICs. The nCDHA was synthesized via an accelerated microwave process and characterized by X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) methods. The synthesized nCDHA was mixed with GIC in different compositions (5, 10 and 15 wt%) maintaining the powder to liquid ratio. Cylinders of dimensions 8 mm height and 4 mm diameter were formed using a Teflon mold following a conventional cement forming technique. The XRD and FT-IR of the cylinders showed increased intensity and characteristic bands of CDHA with increase in nCDHA content. The surface cracks and the elemental composition of the set cements were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Decreased surface hardness was observed for composite cements with increase in nCDHA addition. The cement cylinders were tested for ionic release in Millipore water (pH = 7) via inductive coupled plasma (ICP) spectroscopy and in demineralization solution of pH = 5 to find out the weight loss in an acidic environment at 37 • C performed periodically for 5 weeks. The ionic release percentage, weight loss and compressive strength were observed to increase with an increase in nCDHA addition. c

Cell surface hydrophobicity (CSH) status influences virulence of Candida albicans and decreases the susceptibility of yeast cells to phagocytic killing. We tested whether subinhibitory concentrations of fluconazole, which is widely used in the treatment and prophylaxis of candidiasis, affect CSH and the susceptibility of C. albicans to enzymatic digestion by glucanase and to phagocytic killing. Treatment of yeast cells with subinhibitory fluconazole concentrations resulted in greater phagocytosis. This effect was independent of CSH but may be related to increased cell wall porosity resulting from alterations in the cell envelope. The use of subinhibitory concentrations of fluconazole in patients with competent phagocytes may contribute to resistance to candidiasis regardless of yeast CSH status.

Inverse gas chromatography (IGC) was employed to characterise the surface properties of four batches of ~t-lactose monohydrate supplied as chemically and physically equivalent, but reported to exhibit variable processing performance. These batches were found to be indistinguishable by FT-laser Raman spectroscopy, quantitative X-ray powder diffraction, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and surface area measurement. IGC was undertaken using vapours of polar and non-polar adsorbates or probes introduced individually, in very small quantities, onto the a-lactose monohydrate packed column. The net retention volume, VN, of each probe was determined, allowing the calculation of various surface properties, including the dispersive component of surface free energy (yD) and specific interaction with polar probes (AGSAP). Whilst the ),D values were comparable, AG sa values for polar probes demonstrated significant differences, indicating batch variation in the polar surface properties of the four batches of a-lactose monohydrate. It is hypothesised that these differences in surface energetics are caused by minor variation in surface crystallinity or purity.

Scanning Tunneling Microscope (STM) has been widely used to explore diverse surface properties with an atomic resolution, and STM tip has played a critical role in controlling surface structures. However, detailed information of atomic and electronic structure of STM tip and the fundamental understanding of STM images are still incomplete. Therefore, it is important to develop a comprehensive understanding of the electronic structure of STM tip. We have studied the atomic and electronic structures of STM tip with various transition metals (TMs) by DFT method. The d-electrons of TM tip apex atoms show different orbital states near the Fermi level. We will present comprehensive data of STM tips from our DFT calculation. Verified quantification of the tip electronic structures will lead to fundamental understanding of STM tip structure-property relationship. This work is supported by the DARPA TBN Program and the Texas ETF.

Metallic lead as well as cubic pyrrhotite were produced by the mechanochemical reduction of lead sulphide with elemental iron during milling in a planetary mill Pulverisette 6 (Fritsch, Germany) as a result of the reducing power of iron. The reaction kinetics has been examined by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). The surface properties have been characterized by transmission electron microscopy (TEM). The process of mechanochemical reduction of lead sulphide is quite more straightforward due to the monophase nature of the lead sulphide precursor. Both products are present in the form of Pb/FeS nanoparticles and the average grain size of the freshly formed lead is between 13-21 nm depending on the milling conditions. Unlike the conventional high-temperature reduction of lead sulphide, the mechanochemical reduction is very fast and ambient temperature and atmospheric pressure are sufficient for its propagation.

The number of engineered nanomaterials (ENMs) being exploited commercially is growing rapidly, due to the novel properties they exhibit. Clearly, it is important to understand and minimize any risks to health or the environment posed by the presence of ENMs. Data-driven models that decode the relationships between the biological activities of ENMs and their physicochemical characteristics provide an attractive means of maximizing the value of scarce and expensive experimental data. Although such structure-activity relationship (SAR) methods have become very useful tools for modelling nanotoxicity endpoints (nanoSAR), they have limited robustness and predictivity and, most importantly, interpretation of the models they generate is often very difficult. New computational modelling tools or new ways of using existing tools are required to model the relatively sparse and sometimes lower quality data on the biological effects of ENMs. The most commonly used SAR modelling methods work bes...

Regulation for nanomaterial is urgently needed and the drive to adopt an intelligent testing strategy is evident. The intelligent testing strategy will not only be beneficial from a cost reduction point of view but will also mean the reduction of the moral and ethical concerns related to animal research. In the chemical and legislative world, such an approach is promoted by REACH and in particular the use of (Q)SAR as a tool for the purpose of categorisation. In addition to traditional compounds, (Q)SAR has also been applied to nanomaterials i.e. nano(Q)SAR, useful to correlate toxicological endpoints with physicochemical properties. Although (Q)SAR in chemicals is well established, nano(Q)SAR is still at an early stage of its development and its successful uptake is far from reality. The purpose of this paper is to identify some of the pitfalls and challenges associated with nano-(Q)SARs, in relation for its use to categorise nanomaterials. Our findings show clear gaps in the research framework that must be addressed if we are to have reliable predications from the use of such models. Three major types of barriers were identified: a) the need to improve quality of experimental data in which the models are being developed from in the first place, b) the need to have practical guidelines for the development of the nano(Q)SAR models, c) the need to standardise and harmonise activities for the purpose of regulation. Out of the three barriers, immediate attention is needed for a) as this underpins activities associated in b) and c). It should be noted that the usefulness of data in the context of nano-(Q)SAR modelling is not only about the quantity of data but also about the quality, consistency and accessibility of those data.

This study revealed large distinctions between the lamellar and non-lamellar liquid crystalline lipid phases in their spreading at the air/water interface and propensity to form bilayer foam films. Comparative measurements were made for the lamellar L(alpha), the inverted hexagonal H(II) and the bicontinuous cubic Pn3m phases of the phospholipid dipalmitoleoylphosphatidylethanolamine (DPoPE). With regard to monolayer formation, followed as the decrease of surface tension with time, the best spreading (lowest surface tension) was observed for the L(alpha) phase, and poorest spreading (highest surface tension) was recorded for the H(II) phase. The cubic Pn3m phase of DPoPE, induced by temperature cycling, retained an intermediate position between the L(alpha) and H(II) phases. According to their ability to lower surface tension and disintegrate at the air/water interface, the three phases thus order as L(alpha)&gt;Pn3m&gt;H(II). Clearly expressed threshold (minimum) bulk lipid concent...

To perform a surface chemistry study of the interactions between benzalkonium chloride (BAC), a common preservative used in ophthalmic formulations, and tear film (TF) constituents. METHODS. The interactions between BAC and human tears, meibum, and rabbit corneal cell lipid extracts at the air-water interface were examined in vitro during controlled compression-expansion of the film area by a Langmuir surface balance, surface potential measurements, and pendant drop-axisymmetric drop shape analysis (PD-ADSA). Surface pressure-area isotherms and isocycles were used to assess the sample's lateral elasticity and capability of compressing and spreading during dynamic area changes. Lipid film morphology was monitored by Brewster angle microscopy. The viability of BAC-treated Statens Seruminstitut rabbit cornea (SIRC) cell cultures was also examined. The BAC concentration was kept within the clinical range of 0.001% to 0.02%. RESULTS. In the Langmuir balance and PD-ADSA experiments, the interactions between BAC and lipids or tears resulted in (1) impaired lipid spread and formation of discontinuous nonuniform surface layers, (2) increased surface pressure-area hysteresis during compression and expansion, and (3) displacement of the lipids by BAC from the surface. A decrease (Ͼ50%) in SIRC cell viability was observed. The effects occurred within seconds after BAC exposure, and their magnitude increased with BAC concentration. CONCLUSIONS. The surface chemistry approach used in this study provided molecular-scale insights into the detrimental effect of BAC on TF, which well explain the TF instability and corneal epithelial barrier dysfunction after exposure to BAC in the in vivo human eye. (Invest

In the current work we study with monolayer tensiometry and Brewster angle microscopy (BAM) the surface properties of Dipalmitoleoylphosphatidylethanolamine (DPoPE) Wlms at the air/water interface in presence and absence of speciWc surfactant protein C (SP-C). DPoPE is used, as it readily forms both lamellar (L ) and nonlamellar inverted hexagonal (H II ) phases and appears as a suitable model phospholipid for probing the interfacial properties of distinct lipid phases. At pure air/water interface L shows faster adsorption and better surface disintegration than H II phase. The interaction of DPoPE molecules with SP-C (predeposited at the interface) results in equalizing of the interfacial disintegration of the both phases (reaching approximately the same equilibrium surface tension) although the adsorption kinetics of the lamellar phase remains much faster. Monolayer compression/decompression cycling revealed that the eVect of SP-C on dynamic surface tensions ( max and min ) of mixed Wlms is remarkably diVerent for the two phases. If max for L decreased from the Wrst to the third cycle, the opposite eVect is registered for H II where max increases during cycling. Also the sig-niWcant decrease of min for L in SP-C presence is not observed for H II phase. BAM studies reveal the formation of more uniform and homogeneously packed DPoPE monolayers in the presence of SP-C.

Patients with osteoporosis and joint disabilities represent a constant growing and challenging population to be treated in the musculoskeletal clinical field. Especially in the case of total hip arthroplasty, new solutions should be developed to compensate for the double negative factors, peri‐implant osteolysis, and osteoporotic bone loss, affecting the quality of implant outcome. The goal of this study was then to establish a proof of concept for orthopedic implant used as Zoledronate delivery in osteoporotic rats, and in particular, to verify if this approach could increase the initial implant stability. Twenty‐five female 6‐month‐old Wistar rats were ovariectomized 6 weeks before the implantation to induce osteoporosis. The animals were randomly separated in five groups representing the different Zoledronate concentrations in the HA coating: 0, 0.2, 2.1, 8.5, and 16 μg/implant. Histomorphometric measures and peri‐implant bone volume fraction were assessed and mechanical stabilit...

Poly(2-dimethylamino-ethylmethacrylate) (PDMAEMA) is a cationic polymer when dissolved in a 7.4 pH fluid. Owing to its ionic nature, this polycation interacts with the negatively charged cell membrane surface of red blood cells (RBCs). The electrostatic self-assembly of PDMAEMA on RBCs membrane can be employed for inducing the formation of a polymeric shield camouflaging blood group antigens on RBCs as a valuable strategy for developing "universal RBCs" for blood transfusion. The purpose of this research was to evaluate the camouflaging ability of PDMAEMA homopolymers and PDMAEMA-copoly(ethylene glycol) copolymers differing in molecular weight and architecture. Surprisingly, the PDMAEMAs caused a partially masking, no masking, and sensitization of the same RBCs population. The MW and architecture of the polymers as well as temperature of PDMAEMA-RBCs treatment influenced the results observed. Herein, the very particular reactivity of PDMAEMAs and RBCs is analyzed and discussed.