School of Chemistry and Biochemistry

This paper investigates the extent of the self-assembly process of Au nanoparticles, depending on the nature of structural and functional moieties of various amino acids (L-cystine, glutathione, L-cysteine and N-acetyl cysteine) and their influence on the plasmon sensitivity and electrokinetic parameters in correlation with the catalysis of p-nitrophenol reduction. DLS particle size analysis revealed that the hydrodynamic size 10-20 nm of Au nanospheres was increased to 135-550 nm, 100-460 nm and 130-240 nm after the addition of L-cystine, L-cysteine and glutathione, respectively, in contrast to no significant change of particle size (15-60 nm) after N-acetyl cysteine addition. This difference in the extent of aggregation as a function of structures of amino acids is further evidenced by lengthy tubular arrays formation by glutathione as compared to branched chain like morphology obtained by L-cystine through TEM. FTIR studies further confirmed the binding of amino acids to Au nanospheres via -SH followed by linking of adjacent nanoparticles through H-bonding. Due to the conformational diversity of amino acids, the surface adsorbed -SH, -COOand -NH 3 ? species over assembled Au nanoparticles led to the alteration of zeta potential and conductance, thus affected the catalysis for the reduction of p-nitrophenol as compared to unmodified Au nanoparticles.

This paper demonstrates the preparation of core-shell nanocomposites (NCs) of Aucore-Agshell (Au@Ag)
and Agcore-Aushell (Ag@Au) for measuring their catalytic activity and electro-kinetic properties relative to
their respective monometallic counterparts. A significant blue-shift (530
408 nm) and red-shift (420

550 nm) of the surface plasmon band for Au@Ag and Ag@Au NCs, respectively, was observed due to
10 increased size of binary composites depending on the nature of core and shell material. The thickness of
the deposited Ag shells varied from ~3-10 nm on Au core leading to the formation of Au@Ag NCs. On
the other hand, the Ag core served as a sacrificial template, where Ag@Au NCs was converted to hollow
Ag-Au alloy shells (~15 nm) because of the galvanic reaction between them due to the difference in their
redox potential. Increased zeta potential of resulting Au@Ag (+57.8 mV) and hollow Ag-Au alloy shell (-
15 20.13 mV) NCs in comparison to monometallic Au (-6.13 mV) and Ag nanospheres (-5.74 mV) was
found due to surface passivation with aqueous AgNO3 and AuCl4
- solution, respectively. These bimetallic
NCs exhibited ~2 times higher catalytic activity than the monometallic nanoparticles depending on shell
thickness and the core of the respective metals for the nitrobenzene and 1,3-dinitrobenzene reduction.

Flash chromatography of Methanol, Methanol Water (1:1) and Water extracts of the roots of Angelica archangelica was carried out. The various fractions obtained were subjected to antibacterial activity against four clinically significant strains using Ciprofloxacin (antibiotic) as standard with fractions from methanol extract showing promising activity. One more interesting result was that all the ethyl acetate fractions from Methanol, Methanol Water (1:1) and Water extracts were more active. So these fractions can be further phytochemically investigated for the isolation of biologically active constituents. The positive biological activities manifested by the fractionated extracts from crude extracts render concrete substantiation for the use of such species for traditional medicinal purposes.

The biophysical properties of DNA-modified Au nanoparticles (AuNPs) have attracted a great deal of research interest for various applications in biosensing. AuNPs have strong binding capability to the phosphate and sugar groups in DNA, rendering unique physicochemical properties for detection of metal ions. The formation of Au–DNA nanocomposites is evident from the observed changes in the optical absorption, plasmon band, zeta potential, DLS particle size distribution, as well as TEM and AFM surface morphology analysis. Circular dichroism studies also revealed that DNA-functionalized AuNP binding caused a conformational change in the DNA structure. Due to the size and shape dependent plasmonic interactions of AuNPs (33–78 nm) with DNA, the resultant Au–DNA nanocomposites (NCs) exhibit superior fluorescence emission due to chemical binding with Ca 2+ , Fe 2+ and Mg 2+ ions. A significant increase in fluorescence emission (λ ex = 260 nm) of Au–DNA NCs was observed after selectively binding with Mg 2+ ions (20–800 ppm) in an aqueous solution where a minimum of 100 ppm Mg 2+ ions was detected based on the linearity of concentration versus fluorescence intensity curve (λ em = 400 nm). The effectiveness of Au–DNA nanocomposites was further verified by comparing the known concentration (50–120 ppm) of Mg 2+ ions in synthetic tap water and a real life sample of Gelusil (300–360 ppm Mg 2+), a widely used antacid medicine. Therefore, this method could be a sensitive tool for the estimation of water hardness after careful preparation of a suitably designed Au–DNA nanostructure.

This paper investigates the extent of the self-assembly process of Au
nanoparticles, depending on the nature of structural and functional moieties of
various amino acids (L-cystine, glutathione, L-cysteine and N-acetyl cysteine) and
their influence on the plasmon sensitivity and electrokinetic parameters in correlation
with the catalysis of p-nitrophenol reduction. DLS particle size analysis
revealed that the hydrodynamic size 10–20 nm of Au nanospheres was increased to
135–550 nm, 100–460 nm and 130–240 nm after the addition of L-cystine, L-cysteine
and glutathione, respectively, in contrast to no significant change of particle
size (15–60 nm) after N-acetyl cysteine addition. This difference in the extent of
aggregation as a function of structures of amino acids is further evidenced by
lengthy tubular arrays formation by glutathione as compared to branched chain like
morphology obtained by L-cystine through TEM. FTIR studies further confirmed the
binding of amino acids to Au nanospheres via –SH followed by linking of adjacent
nanoparticles through H-bonding. Due to the conformational diversity of amino
acids, the surface adsorbed –SH, –COO- and –NH3
? species over assembled Au
nanoparticles led to the alteration of zeta potential and conductance, thus affected
the catalysis for the reduction of p-nitrophenol as compared to unmodified Au
nanoparticles.

This paper demonstrates the preparation of core-shell nanocomposites (NCs) of Aucore-Agshell (Au@Ag)
and Agcore-Aushell (Ag@Au) for measuring their catalytic activity and electro-kinetic properties relative to
their respective monometallic counterparts. A significant blue-shift (530
408 nm) and red-shift (420

550 nm) of the surface plasmon band for Au@Ag and Ag@Au NCs, respectively, was observed due to
10 increased size of binary composites depending on the nature of core and shell material. The thickness of
the deposited Ag shells varied from ~3-10 nm on Au core leading to the formation of Au@Ag NCs. On
the other hand, the Ag core served as a sacrificial template, where Ag@Au NCs was converted to hollow
Ag-Au alloy shells (~15 nm) because of the galvanic reaction between them due to the difference in their
redox potential. Increased zeta potential of resulting Au@Ag (+57.8 mV) and hollow Ag-Au alloy shell (-
15 20.13 mV) NCs in comparison to monometallic Au (-6.13 mV) and Ag nanospheres (-5.74 mV) was
found due to surface passivation with aqueous AgNO3 and AuCl4
- solution, respectively. These bimetallic
NCs exhibited ~2 times higher catalytic activity than the monometallic nanoparticles depending on shell
thickness and the core of the respective metals for the nitrobenzene and 1,3-dinitrobenzene reduction.

Highlights  Synthesis of naphthalimide based Schiff base for Hg 2+ /HSO 4 ions detection.  Probe 1 for detection of nanomolar concentration of Hg 2+ and HSO 4 ions. reaction, the probe 1 exhibited a high selectivity and sensitivity for Hg 2+ between 0.5 nM to 0.7 μM, and HSO 4 ions between 50 nM to 40 μM. Furthermore, the probe 1 has been successfully used for studies of the binding interactions with calf thymus (Ct)-DNA. Probe 1 as a DNA intercalator showed fluorescence enhancement upon binding with Ct-DNA and exhibited stronger binding constant as compared to amonafide.

Highlights  Synthesis of naphthalimide based Schiff base for Hg 2+ /HSO 4 ions detection.  Probe 1 for detection of nanomolar concentration of Hg 2+ and HSO 4 ions. reaction, the probe 1 exhibited a high selectivity and sensitivity for Hg 2+ between 0.5 nM to 0.7 μM, and HSO 4 ions between 50 nM to 40 μM. Furthermore, the probe 1 has been successfully used for studies of the binding interactions with calf thymus (Ct)-DNA. Probe 1 as a DNA intercalator showed fluorescence enhancement upon binding with Ct-DNA and exhibited stronger binding constant as compared to amonafide.

Four bacterial strains designated as SNTP-1, NS-2 to NS-4 were isolated from selenium contaminated soils of Nawanshahr-Hoshiarpur region of Punjab, India, by enrichment technique and a consortium was developed using these isolates. The isolates were observed to be belonging to Bacillus sp. In soil microcosm, complete removal was observed by the consortium in selenite augmented soils while the rate of removal with consortia in selenate treatment was 72% after 120 days. Population survival of isolates showed stability at lower treatments and decline at higher levels of Se enrichment. The consortium can, thus, be used for removal of Se contaminated sites.

A B S T R A C T Fracture tests are carried out on extra deep drawn steel CT specimens containing notches with different values of notch root radius (ρ = 0.07-0.75 mm). Experimental findings clearly show a critical notch root radius (ρ c ) below which the fracture toughness remains independent of ρ and above which it varies linearly with ρ. The 3D finite element analysis shows that the location of maximum stress level causing crack initiation is in the vicinity of notch tip. The maximum stress level is independent of ρ; however, its location is shifted away from notch tip along unbroken ligament length with increase in ρ.

Extracellular lipase production by Aspergillus sp. (RBD-01) was monitored by modulating pH of the growth medium, ambient temperature for growth, source of nitrogen and percentage of carbon (virgin cottonseed oil). This strain was observed to be viable and produces lipase even up to 50% oil as a main carbon source. Maximum lipase activity of 21.8 U/ml was obtained with 50% (v/v) oil acting as the main carbon source and peptone (0.5% w/v) as nitrogen source. The optimum pH and temperature for enzymatic activity were observed to be 7.5 and 35 °C, respectively. The observations are of significance due to limited reports on use of 50% of oil as the main carbon source while obtaining significant lipase activity of 21.8 U/ml.