To investigate whether myopia is present in a breed of domestic dog, the Labrador retriever, and ... more To investigate whether myopia is present in a breed of domestic dog, the Labrador retriever, and how the ocular components are related to refractive error in this breed. Cycloplegic refractive error was measured in 75 Labrador retrievers by retinoscopy. Corneal and crystalline lens radii of curvature were measured in the right eyes of 57 of these dogs using a video-based keratophakometer, with axial ocular dimensions measured using A-scan ultrasonography. Of the 75 dogs tested, 11 (14.7%) were myopic by at least -0.50 D in one eye, and 6 (8.0%) were myopic in both eyes (full range of refractive errors, +3.50 D to -5.00 D). Of the 57 dogs with ocular component measurements, seven (12.3%) were myopic by at least -0.50 D in the right eye. There was a significant negative correlation between refractive error and vitreous chamber depth (Spearman r = -0.42; P < 0.001). Myopic eyes had an elongated vitreous chamber depth (10.87+/-0.34 mm for myopic dogs, 10.02+/-0.40 mm for nonmyopic do...
To determine the effect of optical defocus (such as what develops in spontaneous myopia and subse... more To determine the effect of optical defocus (such as what develops in spontaneous myopia and subsequent to cataract extraction) on visual acuity in dogs. 3 young adult male Beagles. The effect of optical defocus on visual acuity was determined by sweep visual evoked potential, using a within-subjects/repeated measures design in which each dog served as its own control. Dogs were positioned so that the eye being tested was 60 cm in front of the video display, and the target was centered on the area centralis. To create ametropia relative to the video screen, a series of concave and convex spherical lenses were placed 1 cm in front of the eye, and sweep visual evoked potential acuities were obtained. Maximal acuity was 7.0 to 9.5 cycles/degree. Defocusing by 2.0 diopters reduces Beagle grating acuity approximately 1 octave. Mimicking aphakia resulted in a marked depression of acuity to 0.7 cycles/degree or less. Even mild degrees of ametropia have appreciable impact on the resolving po...
PURPOSE. We determined whether naturally-occurring lenticular myopia in English Springer spaniels... more PURPOSE. We determined whether naturally-occurring lenticular myopia in English Springer spaniels (ESS) has a genetic component. METHODS. Streak retinoscopy was performed on 226 related ESS 30 minutes after the onset of pharmacologic mydriasis and cycloplegia. A pedigree was constructed to determine relationships between affected offspring and parents. Estimation of heritability was done in a Bayesian analysis (facilitated by the MCMCglmm package of R) of refractive error in a model, including terms for sex and coat color. Myopia was defined as À0.5 diopters (D) spherical equivalent. RESULTS. The median refractive error for ESS was 0.25 D (range, À3.5 to þ4.5 D). Median age was 0.2 years (range, 0.1-15 years). The prevalence of myopia in related ESS was 19% (42/ 226). The ESS had a strong correlation (r ¼ 0.95) for refractive error between the two eyes. Moderate heritability was present for refractive error with a mean value of 0.29 (95% highest probability density, 0.07-0.50). CONCLUSIONS. The distribution of refractive error, and subsequently lenticular myopia, has a moderate genetic component in ESS. Further investigation of genes responsible for regulation of the development of refractive ocular components in canines is warranted.
The effects of the sex of the leader and the subordinate on the relationship between leader role ... more The effects of the sex of the leader and the subordinate on the relationship between leader role assumption (measured by Consideration and Initiating Structure) and subordinate extrinsic, intrinsic...
The effects of foui 1 situational moderators on the relationships between (a) leader behavior and... more The effects of foui 1 situational moderators on the relationships between (a) leader behavior and subordinate satisfaction and (b) leader behavior and subordinate performance were examined in a social services organization. Respondents described their job satisfaction, role clarity, and the behavior of their leaders, while the leaders evaluated the respondents' job performance. Using subgroup moderator analyses, the effect of work unit size was significant, with leader structure related to satisfaction in larger units and consideration related to satisfaction in smaller units. The results confirmed earlier findings that in low-stress jobs consideration enhances satisfaction and performance, but that in high stress jobs, structure is helpful. Also confirmed were results showing that high structure had dysfunctional effects only when accompanied by low consideration. Finally, role clarity did not moderate the relationship between leader behavior and subordinate satisfaction and performance. Recent reviews of the leadership literature have strongly emphasized the need to examine the large number of possible moderators of the relationships between leader behavior and subordinate satisfaction and performance. Many of these reviews have been concerned with the large number of studies that have used the Ohio State leadership scales (e.g.,
ABSTRACT Interpenetrating polymer networks are combinations of two crosslinked polymers. Often, t... more ABSTRACT Interpenetrating polymer networks are combinations of two crosslinked polymers. Often, they exhibit dual phase continuity, meaning that both phases extend continuously throughout the sample. Recent research on IPNs has shown that both nucleation and spinodal decomposition mechanisms are important in the kinetics of phase separation.If the polymers are almost miscible, a microheterogeneous morphology will develop. Under these conditions, the glass transition of the IPN may be very broad, extending the range between the glass transition of the two homopolymers. Such materials are useful for sound and vibration damping. The loss and storage modulus, and tan δ behavior of polymers and IPNs in the glass transition region were evaluated on a quantitative basis, in order to characterize their damping behavior better. Corrections for background in dynamic mechanical spectroscopy studies will be discussed. The storage modulus of polystyrene at 25°C was selected as a standard. The development of a group contribution analysis of the integral area under the linear loss modulus-temperature curves, the loss area, LA, is reviewed, and applied to a number of acrylic, styrenic, and vinyl statistical copolymers and IPNs. Each moiety in a polymer is shown to contribute to LA on a simple, additive basis.New research emphasizes the role of morphology and phase continuity in determining LA. The system cross-poly(vinyl methyl ether)-inter-cross-polystyrene was selected, because its phase diagram in the blend state is well known, and it has become both a model and interesting system to investigate. Midrange IPN compositions exist as two phases at room temperature, as illustrated by dynamic mechanical spectroscopy.
ABSTRACTNanoparticles of CdS (5.0 nm diameter) are prepared in aqueous solution, and copper or si... more ABSTRACTNanoparticles of CdS (5.0 nm diameter) are prepared in aqueous solution, and copper or silver ions are incorporated into the nanoparticle lattice (doped) or adsorbed to the nanoparticle surface (activated). The materials are characterized by ultraviolet-visible spectroscopy, photoluminescence spectroscopy, transmission electron microscopy and electron diffraction. The photoluminescence efficiency of the materials is affected by the concentration of the foreign ion. The effect of spatial location (doped vs. activated) on the spectral distribution of the emission are modest. Photodecomposition of copper-doped CdS is suppressed compared to CdS alone.
Polymer Applications of Renewable-Resource Materials, 1983
Concern for the stability of future petroleum supplies has stimulated much attention in the past ... more Concern for the stability of future petroleum supplies has stimulated much attention in the past few years to feedstocks for polymers based on renewable resources. (1–7). Among these have been the botanical oils, which are usually triglycerides. Indeed, botanical oils have long been employed in applications such as coatings, plasticizers, and in the synthesis of monomers such as brassylic and sebacic acid. More recently, other monomers and polymers have been made, including simultaneous interpenetrating networks (SINs) based on elastomers from various botanical oils coupled with polystyrene networks (PSN) (8–13). In the present work, the goal has been to develop new polymers based on industrial-type oils derived from plants (8,11). To demonstrate feasibility, several unsaturated oils (linseed, crambe, lunaria and lesquerella) were epoxidized and converted to elastomeric components of SIN3; thalictrum oil has also been partially epoxidized and converted to a flexible crosslinked product. The use of epoxy-containing vernonia oil in SINs is described separately (12), and the possible adaptation to reactive injection molding (RIM) processes is proposed elsewhere (13). This paper updates earlier reports (8,11) and reviews the synthesis, morphologies,and properties of SINs based in part on epoxidized botanical oils.
Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.
The dissociative adsorption of hydrogen on cobalt is central to a number of catalytic reactions, ... more The dissociative adsorption of hydrogen on cobalt is central to a number of catalytic reactions, yet to date there are relatively few studies examining this important process. Here we utilize Co nanoparticles grown on Cu(111), instead of the traditional planar Co single crystals, to study a more catalytically relevant form of Co. We present scanning tunneling microscopy images of different phases of H on the close-packed Co nanoparticle surfaces with a range of densities. Our data reveal a so-far unreported high coverage phase of H with a (1 × 1) structure and elucidate the importance of spillover from step edges in H adsorption. We also illustrate that, in contrast to the low density phases, the H-(1 × 1) structure can only be formed at an intermediate temperature, indicating that compression to this higher-density phase is activated. Density functional theory calculations yield energies for each of the H overlayer structures, as well as their preferred geometries. This work is the first to report on higher coverage (>0.75 ML) phases of H on Co, which are undoubtedly important in catalytic systems at elevated pressure. Finally, through the use of epitaxial Co nanoparticle growth on Cu(111), we illustrate the importance of step edges in H 2 activation and the formation of dense H phases.
Silver nanowires fabricated using a wet-chemical synthesis have been characterized in UHV using s... more Silver nanowires fabricated using a wet-chemical synthesis have been characterized in UHV using scanning tunneling microscopy. The nanowires have a faceted structure with a high density of steps at the facet boundaries. Monolayer height steps are easily imaged, and have measurable temporal fluctuations at room temperature. Measurement of the step time correlation functions shows that the steps fluctuate via periphery diffusion, with a hopping time constant of 0.10 0.24 s. The symmetry of islands on the facets and the quantitative step characteristics are both consistent with (1 0 0) oriented facets, in agreement with previous TEM characterization.
ABSTRACT The relationships between equilibrium melting temperatures (Tm*) and crystalline morphol... more ABSTRACT The relationships between equilibrium melting temperatures (Tm*) and crystalline morphology of poly[3,3bis(ethoxymethyl)oxetane], (polyBEMO), poly[3,3-bis (azidomethyl)oxetane], (polyBAMO), and poly(ethylene oxide), (PEO), were characterized. The Hoffman-Weeks extrapolation procedure led to Tm* values of 92, 102, and 69°C for these three polymers, respectively. The gross morphologies of polyBEMO, polyBAMO, and PEO were studied as a function of melt-liquid temperature (Ti) and isothermal crystallization temperature (Tc) by visible light microscopy. Spherulitic morphologies were observed for polyBEMO, polyBAMO, and PEO when Ti was above Tm*, while nonspherulitic (hedritic) morphologies were observed at Tls below Tm*. Mixed morphologies were observed when Tl was approximately equal to Tm*.
ABSTRACT Gold nanocrystals of different shapes have been made by a wet chemical approach based on... more ABSTRACT Gold nanocrystals of different shapes have been made by a wet chemical approach based on a two-step, seed-mediated synthesis. In this paper, we demonstrate a one-step synthetic method for achieving simple and systematic control over the shape of gold nanoparticles. Gold nanowires, which have been prepared by multi-step approaches, are produced in very high yield in this single-step technique. The width of the rods can be varied over a broader range compared to previously reported methods. Rectangle-, cube- or tetrapod-like gold nanocrystals can also be prepared in aqueous solution at room temperature. The formation of various shapes, in the presence of silver nitrate, requires bromide ion and alkylammonium surfactant ion of appropriate hydrocarbon tail length. The shape, dimension and yield of the nanocrystals depend on the nature and concentrations of the stabilizing cationic surfactants and other additives, such as salts, in addition to the reactants.
Evidence exists that BRCA2 carriers may have an elevated risk of breast, ovarian, colon, prostate... more Evidence exists that BRCA2 carriers may have an elevated risk of breast, ovarian, colon, prostate, and pancreatic cancer. In general, carriers are defined as individuals with protein truncating mutations within the BRCA2 gene. Many Brca2 knockout lines have been produced and characterized in the mouse. We previously produced a rat Brca2 knockout strain in which there is a nonsense mutation in exon 11 between BRC repeats 2 and 3, and a truncated protein is produced. Interestingly, while such a mutation in homozygous mice would lead to limited survival of approximately 3 months, the Brca2 À/À rats are 100% viable and the vast majority live to over 1 year of age. Brca2 À/À rats show a phenotype of growth inhibition and sterility in both sexes. Aspermatogenesis in the Brca2 À/À rats is due to a failure of homologous chromosome synapsis. Long-term phenotypes include underdeveloped mammary glands, cataract formation and lifespan shortening due to the development of tumors and cancers in multiple organs. The establishment of the rat Brca2 knockout model provides a means to study the role of Brca2 in increasing cancer susceptibility and inducing a novel ocular phenotype not previously associated with this gene.
ENTEROBIUS (formerly called "Oxyuris") vermicularis is the most common metazoan parasit... more ENTEROBIUS (formerly called "Oxyuris") vermicularis is the most common metazoan parasite of man. Despite its world-wide prevalence, its pathogenicity is very low, and it rarely strays from its usual habitat in the intestinal tract and the perianal skin. It is our purpose to report the case of a girl in whom the organism apparently caused a salpingooophoritis, and to review briefly the literature of atypical infestation. The infestation, though extremely prevalent, is quite variable throughout the world, in various sections of the country, and even in various social classes. Thus, Weller and Sorenson1 reported a prevalence of 19 per . . .
A multilobular tumour of bone with left orbital involvement was diagnosed at post mortem examinat... more A multilobular tumour of bone with left orbital involvement was diagnosed at post mortem examination in an eight-year-old German shepherd cross dog. The tumour resulted in progressive exophthalmos with lateral deviation of the left eye. Radiographs revealed that the mass was mineralised and originated from the left frontal bone with invasion of the left frontal sinus and destruction of the cribriform plate. This is the third reported case of this type of tumour involving the orbit of the dog and thus multilobular tumour of bone should be considered as a differential diagnosis of exophthalmos.
To investigate whether myopia is present in a breed of domestic dog, the Labrador retriever, and ... more To investigate whether myopia is present in a breed of domestic dog, the Labrador retriever, and how the ocular components are related to refractive error in this breed. Cycloplegic refractive error was measured in 75 Labrador retrievers by retinoscopy. Corneal and crystalline lens radii of curvature were measured in the right eyes of 57 of these dogs using a video-based keratophakometer, with axial ocular dimensions measured using A-scan ultrasonography. Of the 75 dogs tested, 11 (14.7%) were myopic by at least -0.50 D in one eye, and 6 (8.0%) were myopic in both eyes (full range of refractive errors, +3.50 D to -5.00 D). Of the 57 dogs with ocular component measurements, seven (12.3%) were myopic by at least -0.50 D in the right eye. There was a significant negative correlation between refractive error and vitreous chamber depth (Spearman r = -0.42; P < 0.001). Myopic eyes had an elongated vitreous chamber depth (10.87+/-0.34 mm for myopic dogs, 10.02+/-0.40 mm for nonmyopic do...
To determine the effect of optical defocus (such as what develops in spontaneous myopia and subse... more To determine the effect of optical defocus (such as what develops in spontaneous myopia and subsequent to cataract extraction) on visual acuity in dogs. 3 young adult male Beagles. The effect of optical defocus on visual acuity was determined by sweep visual evoked potential, using a within-subjects/repeated measures design in which each dog served as its own control. Dogs were positioned so that the eye being tested was 60 cm in front of the video display, and the target was centered on the area centralis. To create ametropia relative to the video screen, a series of concave and convex spherical lenses were placed 1 cm in front of the eye, and sweep visual evoked potential acuities were obtained. Maximal acuity was 7.0 to 9.5 cycles/degree. Defocusing by 2.0 diopters reduces Beagle grating acuity approximately 1 octave. Mimicking aphakia resulted in a marked depression of acuity to 0.7 cycles/degree or less. Even mild degrees of ametropia have appreciable impact on the resolving po...
PURPOSE. We determined whether naturally-occurring lenticular myopia in English Springer spaniels... more PURPOSE. We determined whether naturally-occurring lenticular myopia in English Springer spaniels (ESS) has a genetic component. METHODS. Streak retinoscopy was performed on 226 related ESS 30 minutes after the onset of pharmacologic mydriasis and cycloplegia. A pedigree was constructed to determine relationships between affected offspring and parents. Estimation of heritability was done in a Bayesian analysis (facilitated by the MCMCglmm package of R) of refractive error in a model, including terms for sex and coat color. Myopia was defined as À0.5 diopters (D) spherical equivalent. RESULTS. The median refractive error for ESS was 0.25 D (range, À3.5 to þ4.5 D). Median age was 0.2 years (range, 0.1-15 years). The prevalence of myopia in related ESS was 19% (42/ 226). The ESS had a strong correlation (r ¼ 0.95) for refractive error between the two eyes. Moderate heritability was present for refractive error with a mean value of 0.29 (95% highest probability density, 0.07-0.50). CONCLUSIONS. The distribution of refractive error, and subsequently lenticular myopia, has a moderate genetic component in ESS. Further investigation of genes responsible for regulation of the development of refractive ocular components in canines is warranted.
The effects of the sex of the leader and the subordinate on the relationship between leader role ... more The effects of the sex of the leader and the subordinate on the relationship between leader role assumption (measured by Consideration and Initiating Structure) and subordinate extrinsic, intrinsic...
The effects of foui 1 situational moderators on the relationships between (a) leader behavior and... more The effects of foui 1 situational moderators on the relationships between (a) leader behavior and subordinate satisfaction and (b) leader behavior and subordinate performance were examined in a social services organization. Respondents described their job satisfaction, role clarity, and the behavior of their leaders, while the leaders evaluated the respondents' job performance. Using subgroup moderator analyses, the effect of work unit size was significant, with leader structure related to satisfaction in larger units and consideration related to satisfaction in smaller units. The results confirmed earlier findings that in low-stress jobs consideration enhances satisfaction and performance, but that in high stress jobs, structure is helpful. Also confirmed were results showing that high structure had dysfunctional effects only when accompanied by low consideration. Finally, role clarity did not moderate the relationship between leader behavior and subordinate satisfaction and performance. Recent reviews of the leadership literature have strongly emphasized the need to examine the large number of possible moderators of the relationships between leader behavior and subordinate satisfaction and performance. Many of these reviews have been concerned with the large number of studies that have used the Ohio State leadership scales (e.g.,
ABSTRACT Interpenetrating polymer networks are combinations of two crosslinked polymers. Often, t... more ABSTRACT Interpenetrating polymer networks are combinations of two crosslinked polymers. Often, they exhibit dual phase continuity, meaning that both phases extend continuously throughout the sample. Recent research on IPNs has shown that both nucleation and spinodal decomposition mechanisms are important in the kinetics of phase separation.If the polymers are almost miscible, a microheterogeneous morphology will develop. Under these conditions, the glass transition of the IPN may be very broad, extending the range between the glass transition of the two homopolymers. Such materials are useful for sound and vibration damping. The loss and storage modulus, and tan δ behavior of polymers and IPNs in the glass transition region were evaluated on a quantitative basis, in order to characterize their damping behavior better. Corrections for background in dynamic mechanical spectroscopy studies will be discussed. The storage modulus of polystyrene at 25°C was selected as a standard. The development of a group contribution analysis of the integral area under the linear loss modulus-temperature curves, the loss area, LA, is reviewed, and applied to a number of acrylic, styrenic, and vinyl statistical copolymers and IPNs. Each moiety in a polymer is shown to contribute to LA on a simple, additive basis.New research emphasizes the role of morphology and phase continuity in determining LA. The system cross-poly(vinyl methyl ether)-inter-cross-polystyrene was selected, because its phase diagram in the blend state is well known, and it has become both a model and interesting system to investigate. Midrange IPN compositions exist as two phases at room temperature, as illustrated by dynamic mechanical spectroscopy.
ABSTRACTNanoparticles of CdS (5.0 nm diameter) are prepared in aqueous solution, and copper or si... more ABSTRACTNanoparticles of CdS (5.0 nm diameter) are prepared in aqueous solution, and copper or silver ions are incorporated into the nanoparticle lattice (doped) or adsorbed to the nanoparticle surface (activated). The materials are characterized by ultraviolet-visible spectroscopy, photoluminescence spectroscopy, transmission electron microscopy and electron diffraction. The photoluminescence efficiency of the materials is affected by the concentration of the foreign ion. The effect of spatial location (doped vs. activated) on the spectral distribution of the emission are modest. Photodecomposition of copper-doped CdS is suppressed compared to CdS alone.
Polymer Applications of Renewable-Resource Materials, 1983
Concern for the stability of future petroleum supplies has stimulated much attention in the past ... more Concern for the stability of future petroleum supplies has stimulated much attention in the past few years to feedstocks for polymers based on renewable resources. (1–7). Among these have been the botanical oils, which are usually triglycerides. Indeed, botanical oils have long been employed in applications such as coatings, plasticizers, and in the synthesis of monomers such as brassylic and sebacic acid. More recently, other monomers and polymers have been made, including simultaneous interpenetrating networks (SINs) based on elastomers from various botanical oils coupled with polystyrene networks (PSN) (8–13). In the present work, the goal has been to develop new polymers based on industrial-type oils derived from plants (8,11). To demonstrate feasibility, several unsaturated oils (linseed, crambe, lunaria and lesquerella) were epoxidized and converted to elastomeric components of SIN3; thalictrum oil has also been partially epoxidized and converted to a flexible crosslinked product. The use of epoxy-containing vernonia oil in SINs is described separately (12), and the possible adaptation to reactive injection molding (RIM) processes is proposed elsewhere (13). This paper updates earlier reports (8,11) and reviews the synthesis, morphologies,and properties of SINs based in part on epoxidized botanical oils.
Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.
The dissociative adsorption of hydrogen on cobalt is central to a number of catalytic reactions, ... more The dissociative adsorption of hydrogen on cobalt is central to a number of catalytic reactions, yet to date there are relatively few studies examining this important process. Here we utilize Co nanoparticles grown on Cu(111), instead of the traditional planar Co single crystals, to study a more catalytically relevant form of Co. We present scanning tunneling microscopy images of different phases of H on the close-packed Co nanoparticle surfaces with a range of densities. Our data reveal a so-far unreported high coverage phase of H with a (1 × 1) structure and elucidate the importance of spillover from step edges in H adsorption. We also illustrate that, in contrast to the low density phases, the H-(1 × 1) structure can only be formed at an intermediate temperature, indicating that compression to this higher-density phase is activated. Density functional theory calculations yield energies for each of the H overlayer structures, as well as their preferred geometries. This work is the first to report on higher coverage (>0.75 ML) phases of H on Co, which are undoubtedly important in catalytic systems at elevated pressure. Finally, through the use of epitaxial Co nanoparticle growth on Cu(111), we illustrate the importance of step edges in H 2 activation and the formation of dense H phases.
Silver nanowires fabricated using a wet-chemical synthesis have been characterized in UHV using s... more Silver nanowires fabricated using a wet-chemical synthesis have been characterized in UHV using scanning tunneling microscopy. The nanowires have a faceted structure with a high density of steps at the facet boundaries. Monolayer height steps are easily imaged, and have measurable temporal fluctuations at room temperature. Measurement of the step time correlation functions shows that the steps fluctuate via periphery diffusion, with a hopping time constant of 0.10 0.24 s. The symmetry of islands on the facets and the quantitative step characteristics are both consistent with (1 0 0) oriented facets, in agreement with previous TEM characterization.
ABSTRACT The relationships between equilibrium melting temperatures (Tm*) and crystalline morphol... more ABSTRACT The relationships between equilibrium melting temperatures (Tm*) and crystalline morphology of poly[3,3bis(ethoxymethyl)oxetane], (polyBEMO), poly[3,3-bis (azidomethyl)oxetane], (polyBAMO), and poly(ethylene oxide), (PEO), were characterized. The Hoffman-Weeks extrapolation procedure led to Tm* values of 92, 102, and 69°C for these three polymers, respectively. The gross morphologies of polyBEMO, polyBAMO, and PEO were studied as a function of melt-liquid temperature (Ti) and isothermal crystallization temperature (Tc) by visible light microscopy. Spherulitic morphologies were observed for polyBEMO, polyBAMO, and PEO when Ti was above Tm*, while nonspherulitic (hedritic) morphologies were observed at Tls below Tm*. Mixed morphologies were observed when Tl was approximately equal to Tm*.
ABSTRACT Gold nanocrystals of different shapes have been made by a wet chemical approach based on... more ABSTRACT Gold nanocrystals of different shapes have been made by a wet chemical approach based on a two-step, seed-mediated synthesis. In this paper, we demonstrate a one-step synthetic method for achieving simple and systematic control over the shape of gold nanoparticles. Gold nanowires, which have been prepared by multi-step approaches, are produced in very high yield in this single-step technique. The width of the rods can be varied over a broader range compared to previously reported methods. Rectangle-, cube- or tetrapod-like gold nanocrystals can also be prepared in aqueous solution at room temperature. The formation of various shapes, in the presence of silver nitrate, requires bromide ion and alkylammonium surfactant ion of appropriate hydrocarbon tail length. The shape, dimension and yield of the nanocrystals depend on the nature and concentrations of the stabilizing cationic surfactants and other additives, such as salts, in addition to the reactants.
Evidence exists that BRCA2 carriers may have an elevated risk of breast, ovarian, colon, prostate... more Evidence exists that BRCA2 carriers may have an elevated risk of breast, ovarian, colon, prostate, and pancreatic cancer. In general, carriers are defined as individuals with protein truncating mutations within the BRCA2 gene. Many Brca2 knockout lines have been produced and characterized in the mouse. We previously produced a rat Brca2 knockout strain in which there is a nonsense mutation in exon 11 between BRC repeats 2 and 3, and a truncated protein is produced. Interestingly, while such a mutation in homozygous mice would lead to limited survival of approximately 3 months, the Brca2 À/À rats are 100% viable and the vast majority live to over 1 year of age. Brca2 À/À rats show a phenotype of growth inhibition and sterility in both sexes. Aspermatogenesis in the Brca2 À/À rats is due to a failure of homologous chromosome synapsis. Long-term phenotypes include underdeveloped mammary glands, cataract formation and lifespan shortening due to the development of tumors and cancers in multiple organs. The establishment of the rat Brca2 knockout model provides a means to study the role of Brca2 in increasing cancer susceptibility and inducing a novel ocular phenotype not previously associated with this gene.
ENTEROBIUS (formerly called "Oxyuris") vermicularis is the most common metazoan parasit... more ENTEROBIUS (formerly called "Oxyuris") vermicularis is the most common metazoan parasite of man. Despite its world-wide prevalence, its pathogenicity is very low, and it rarely strays from its usual habitat in the intestinal tract and the perianal skin. It is our purpose to report the case of a girl in whom the organism apparently caused a salpingooophoritis, and to review briefly the literature of atypical infestation. The infestation, though extremely prevalent, is quite variable throughout the world, in various sections of the country, and even in various social classes. Thus, Weller and Sorenson1 reported a prevalence of 19 per . . .
A multilobular tumour of bone with left orbital involvement was diagnosed at post mortem examinat... more A multilobular tumour of bone with left orbital involvement was diagnosed at post mortem examination in an eight-year-old German shepherd cross dog. The tumour resulted in progressive exophthalmos with lateral deviation of the left eye. Radiographs revealed that the mass was mineralised and originated from the left frontal bone with invasion of the left frontal sinus and destruction of the cribriform plate. This is the third reported case of this type of tumour involving the orbit of the dog and thus multilobular tumour of bone should be considered as a differential diagnosis of exophthalmos.
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