Search

Potential-step experiments on yttrium thin films show exponential decay of the current as a function of time. A diffusion model for a thin-layer system relates the time constants to effective diffusion coefficients for hydrogen in the di- and trihydride concentration range. The diffusion coefficient is found to be concentration-dependent. From the temperature dependence of the diffusion coefficients and the optical switching time, activation energies are calculated. The good agreement with literature values supports the model of diffusion-limited kinetics for the optical switching.

Emission spectra of nanocrystalline ZnS:Mn2+ have been recorded as a function of temperature between 4 and 300 K . For the two emission bands observed (a defect-related emission band around 420 nm and a Mn2+-related emission band around 590 nm ), the temperature dependence of the width and the position of the emission bands has been analyzed. The shift and the broadening of the Mn2+ emission can be satisfactorily explained by theoretical models and parameters for electron–phonon coupling that are similar to those for bulk ZnS. For the defect-related emission, the shift to lower energies follows the decrease in bandgap of bulk ZnS with increasing temperature. The width of the defect-related emission decreases as the temperature is raised. This anomalous behavior is explained by inhomogeneous broadening at low temperatures.

Heavy metal contamination in an area immediately surrounding a zinc smelter has resulted in destruction of over 485 hectares of forest. The elevated levels of heavy metals in these soils have had significant impacts on the population size and overall activity of the soil microbial communities. Remediation of these soils has resulted in increases in indicators of biological activity and viable population size, which suggest recovery of the microbial populations. Questions remain as to how the metal contamination and subsequent remediation at this site have impacted the population structure of the soil microbial communities. In the current study, microbial communities from this site were analyzed by the phospholipid fatty acid (PLFA) procedure. Principal component analysis of the PLFA profiles indicated that there were differences in the profiles for soils with different levels of metal contamination, and that soils with higher levels of metal contamination showed decreases in indicator PLFAs for mycorrhizal fungi, Gram-positive bacteria, fungi, and actinomycetes. PLFA profiles for remediated sites indicated that remediated soils showed increases in indicator PLFAs for fungi, actinomycetes, and Gram-positive bacteria, compared to unremediated metal contaminated soils. These data suggest a change in the population structure of the soil microbial communities resulting from metal contamination and a recovery of several microbial populations resulting from remediation.

Electroluminescence is observed during porous etching of n-type GaP single crystals at strongly positive potential. The emission spectra, which include a supra-bandgap contribution, are markedly different from the spectra observed under optical excitation or minority carrier injection. The current density and electroluminescence intensity show a strong potential dependence and a similar hysteresis. The spectral characteristics of the luminescence suggest that both thermalised and hot charge carriers, generated by impact ionisation, are involved in light emission.

Laparoscopic adrenalectomy (LA) is a preferred method for the removal of small adrenal masses. However, the role of LA for surgical treatment of large adrenal masses is less established. We evaluated the outcomes of LA for large (>/=5 cm) adrenal masses. We retrospectively reviewed 24 consecutive patients who underwent LA for large adrenal masses at a tertiary care university hospital. The average age of the 24 patients was 49 years, and each underwent laparoscopic resection of a large adrenal mass. All LAs were performed via a lateral transperitoneal approach. The average (+/- standard deviation) size of the masses was 6.8 +/- 1.5 cm (range, 5-11). Pathologic diagnoses included adrenal cortical adenoma (10 cases), pheochromocytoma ( 7), cyst/pseudocyst ( 3), myolipoma ( 2), and adrenal cortical hyperplasia ( 2). Statistical analysis was performed with a two-sample t test. The average operating time was 178 +/- 55 minutes (range, 120-300), and average blood loss was 87 +/- 69 mL (range, 20-300); the averages were nonsignificantly greater in the right LA group than in the left LA group (203 vs. 166 minutes, P = 0.89; 124 vs. 77 mL, P = 0.14). The average duration of nothing-by-mouth (NPO) status was 0.7 days (range, 0-4), and the average time until return to a regular diet was 1.74 +/- 0.9 days (range, 1-5). The average length of stay was 2.5 +/- 1.9 days (range, 1-10). One patient had a transient episode of pseudomembranous colitis. There were no conversions to open adrenalectomy and no major morbidities or mortalities. LA is safe and effective for surgical treatment of large adrenal masses. Both right and left large adrenal masses can be approached laparoscopically with equal success. The role of minimally invasive approaches to adrenal malignancies necessitates further investigation.

Objectives: The primary purpose of this study was to evaluate whether severely injured geriatric patients were as likely to be treated at designated trauma centers (TCs) within the statewide trauma system. The secondary objective was to compare the demographic and injury characteristics of severely injured older and young patients who received care in TCs with the characteristics of those patients cared for in non-TCs. Methods: The authors reviewed files for all acute injury discharges in Pennsylvania for 1997. Injury diagnoses were mapped to Abbreviated Injury Scale (AIS) scores using ICDMAP software; the Injury Severity Score (ISS) was computed. The frequency of hospital discharges for injury from TC and non-TC hospitals in both the older (E) (≥65 years) and younger (Y) ( 15; 5,855 were Y and 3,125 were E. Forty-seven percent of the Y patients received TC care compared with only 36.6% of the E patients (p < 0.001). Logistic regression analysis showed that age was a strongly negative predictor for TC care when injury severity was controlled. Conclusions: Seriously injured older patients were less likely to receive care in a trauma center than younger patients.

Background: We reviewed our experience with complications following laparoscopic Roux-en-Y gastric bypass (LRYGB) that were managed laparoscopically. Methods: A total of 246 consecutive morbidly obese patients (mean body mass index, 50.9 kg/m2) underwent LRYGB by three surgeons at two institutions. All patients met National Institutes of Health criteria for surgical treatment of morbid obesity. Patients were followed prospectively. Results: A total of 62 patients (25.2%) developed 64 complications, 34 of which (13.8%) required a surgical intervention. Twenty-seven of the 34 procedures were performed laparoscopically. Gastrojejunostomy stricture was the most common complication (8.9%), followed by intestinal obstruction (7.3%) and gastrointestinal bleeding (4%). The intestinal obstruction was secondary to adhesions (n = 6), internal hernia at the level of the transverse mesocolon (n = 3), jejunojejunostomy stricture (n = 3), and cicatrix around the Roux limb at the level of the transverse mesocolon (n = 3). Other complications included gastrojejunostomy leak (1.6%), symptomatic gallstone disease (2.8%), and gastric remnant perforation (0.8%). One patient underwent a negative laparoscopy to rule out anastomotic leak. There were 3 deaths in this series of patients, 2 attributable to anastomotic leak. Conclusions: A variety of complications can present after LRYGB. Laparoscopy is an excellent technique to treat these complications.

The aim of this study was to assess the electrodiagnostic (EDx) sensitivity of proximal lower extremity muscles, including tensor fascia lata (TFL) and gluteus medius (GMED), in the diagnosis of L5 radiculopathy.Eleven EDx recordings with L5 radiculopathy were collected. The motor unit action potentials were assessed for morphology, stability, and firing characteristics. A descriptive analysis was performed. In proximal L5-supplied muscles, 4 of 11 recordings were abnormal in TFL only, with normal GMED; 4 of 11 recordings had similar findings in both muscles; 2 of 11 had abnormal findings in both muscles, but TFL had more noticeable findings; and 1 had abnormal findings in both muscles, but GMED findings were more noticeable. No patient had abnormalities limited to GMED. TFL was more sensitive than GMED in detecting L5 radiculopathy. Knowing which muscles are more likely to show abnormalities can improve the efficiency of EMG and reduce patient discomfort. Muscle Nerve 45: 891-893, 2012.

DNA microchip technology is a rapid, high-throughput method for nucleic acid hybridization reactions. This technology requires random fragmentation and fluorescent labeling of target nucleic acids prior to hybridization. Radical-generating coordination complexes, such as 1,10-phenanthroline-Cu(II) (OP-Cu) and Fe(II)-EDTA (Fe-EDTA), have been commonly used as sequence nonspecific "chemical nucleases" to introduce single-strand breaks in nucleic acids. Here we describe a new method based on these radical-generating complexes for random fragmentation and labeling of both single- and double-stranded forms of RNA and DNA. Nucleic acids labeled with the OP-Cu and the Fe-EDTA protocols revealed high hybridization specificity in hybridization with DNA microchips containing oligonucleotide probes selected for identification of 16S rRNA sequences of the Bacillus group microorganisms. We also demonstrated cDNA- and cRNA-labeling and fragmentation with this method. Both the OP-Cu and Fe-EDTA fragmentation and labeling procedures are quick and inexpensive compared to other commonly used methods. A column-based version of the described method does not require centrifugation and therefore is promising for the automation of sample preparations in DNA microchip technology as well as in other nucleic acid hybridization studies.

Aortobifemoral bypass grafting is the treatment of choice for patients with symptomatic aortoiliac occlusive disease. Yet, traditional operative exposure through a midline laparotomy incision carries significant morbidity. The authors compare operative and patient outcomes following hand-assisted laparoscopic aortobifemoral (HALABF) bypass and open aortobifemoral (OABF) bypass.An initial series of patients who underwent HALABF bypass grafting (n = 8) were compared with a simultaneous cohort of patients treated with standard open bypass (n = 10). The two groups were similar with respect to age, weight, and sex. Operative parameters, clinical outcomes, and complications were compared.HALABF was successfully performed in all eight cases attempted. Operative times did not differ between the laparoscopic and open groups (234 +/- 42 minutes vs. 206 +/- 43 minutes, P =.99). Mean blood loss values were comparable (562 mL [HALABF] vs. 756 mL [OABF], P =.56). There were no conversions. Time to resumption of oral intake (1.8 vs. 4.7 days, P =.001) and length of stay (3.8 vs. 6.3 days, P =.0004) were significantly shorter in the laparoscopic than in the open group.HALABF is a safe and technically feasible procedure. When compared with the traditional open operation, this technique may result in shorter hospitalization, more rapid return of bowel function, and earlier return to activity.

Introduction:The Glasgow Coma Scale (GCS) is the standard measure used to quantify the level of consciousness of patients who have sustained head injuries. Rapid and accurate GCS scoring is essential.Objective:To evaluate the effectiveness of a GCS teaching video shown to prehospital emergency medical services (EMS) providers.Methods:Participants and setting—United States, Mid-Atlantic region EMS providers. Intervention—Each participant scored all of the three components of the GCS for each of four scenarios provided before and after viewing a video-tape recording containing four scenarios. Design—Before-and-after single (Phase I) and parallel Cohort (Phase II). Analysis— Proportions of correct scores were compared using chi-square, and relative risk was calculated to measure the strength of the association.Results:75 participants were included in Phase I. In Phase II, 46 participants participated in a parallel cohort design: 20 used GCS reference cards and 26 did not use the cards. Before observing the instructional video, only 14.7% score all of the scenarios correctly, where as after viewing the video, 64.0% scored the scenarios results were observed after viewing the video for those who used the GCS cards (p = 0.001; RR = 2.0; 95% CI = 1.29 to 3.10) than for those not using the cards (p Conclusions:Post-video viewing scores were better than those observed before the video presentation. Ongoing evaluations include analysis of longterm skill retention and scoring accuracy in the clinical environment.

A mesophilic toluene-degrading consortium (TDC) and an ethylbenzene-degrading consortium (EDC) were established under sulfate-reducing conditions. These consortia were first characterized by denaturing gradient gel electrophoresis (DGGE) fingerprinting of PCR-amplified 16S rRNA gene fragments, followed by sequencing. The sequences of the major bands (T-1 and E-2) belonging to TDC and EDC, respectively, were affiliated with the family Desulfobacteriaceae . Another major band from EDC (E-1) was related to an uncultured non-sulfate-reducing soil bacterium. Oligonucleotide probes specific for the 16S rRNAs of target organisms corresponding to T-1, E-1, and E-2 were designed, and hybridization conditions were optimized for two analytical formats, membrane and DNA microarray hybridization. Both formats were used to characterize the TDC and EDC, and the results of both were consistent with DGGE analysis. In order to assess the utility of the microarray format for analysis of environmental samples, oil-contaminated sediments from the coast of Kuwait were analyzed. The DNA microarray successfully detected bacterial nucleic acids from these samples, but probes targeting specific groups of sulfate-reducing bacteria did not give positive signals. The results of this study demonstrate the limitations and the potential utility of DNA microarrays for microbial community analysis.

The blood pressure-raising effects of adrenocortical steroids with predominantly glucocorticoid activity, both naturally occurring and synthetic, are well known. Recent evidence suggests that the nitric oxide system plays a key role in the hypertension produced by glucocorticoids. Glucocorticoid actions at various sites in the nitric oxide synthase (NOS) pathway may result in elevated blood pressure. These include: alterations in l-arginine availability or transport; NOS2 and NOS3 downregulation; reduced cofactor bioavailability; NOS uncoupling; a concomitant elevation in reactive oxygen species and removal of nitric oxide (NO) from the vascular environment; alterations in whole body antioxidant status; and erythropoietin induced resistance to NO.

Recent research has documented microplastic particles (5 mm in diameter) in ocean habitats worldwide and in the Laurentian Great Lakes. Microplastic interacts with biota, including microorganisms, in these habitats, raising concerns about its ecological effects. Rivers may transport microplastic to marine habitats and the Great Lakes, but data on microplastic in rivers is limited. In a highly urbanized river in Chicago, Illinois, USA, we measured concentrations of microplastic that met or exceeded those measured in oceans and the Great Lakes, and we demonstrated that wastewater treatment plant effluent was a point source of microplastic. Results from high-throughput sequencing showed that bacterial assemblages colonizing microplastic within the river were less diverse and were significantly different in taxonomic composition compared to those from the water column and suspended organic matter. Several taxa that include plastic decomposing organisms and pathogens were more abundant on microplastic. These results demonstrate that microplastic in rivers are a distinct microbial habitat and may be a novel vector for the downstream transport of unique bacterial assemblages. In addition, this study suggests that urban rivers are an overlooked and potentially significant component of the global microplastic life cycle.

There is evidence implicating abnormalities in the nitric oxide (NO) pathway in the development of glucocorticoid-induced hypertension (GC-HT). In humans, a reduction in NO availability during cortisol treatment has been observed. This study examined whether the NO donation may reverse the elevated blood pressure (BP) observed with cortisol treatment. A randomised double-blind, placebo-controlled, crossover study was undertaken in eight healthy men to address the effect of co-administration of isosorbide mononitrate (ISMN, 60 mg single dose, day 5) with cortisol (200 mg per day, days 1-6) and then compared with placebo (single dose, day 5) with cortisol. After a 2-week washout period, subjects crossed over to the alternate treatment. BP measurements were obtained using a mercury sphygmomanometer. Tonometry was used to estimate central pressures. There was a significant rise in mean arterial pressure with cortisol: 80 ± 3 vs 89 ± 3 mm Hg (day 1 vs day 5, cortisol+ISMN phase, P < 0.001) and 81 ± 3 vs 89 ± 3 mm Hg (day 1 vs day 5, cortisol+placebo phase, P < 0.01). ISMN significantly decreased aortic augmentation index: -17.3 ± 3.2 vs 1.8 ± 3.5%, (differences calculated from day 5-day 1, cortisol/ISMN vs cortisol+placebo, P < 0.001). These results demonstrated that GC-HT can be modified by co-administration of exogenous NO donors, consistent with the hypothesis that GC-HT is accompanied by reduced NO activity in humans.

The use of diverse engineered nanomaterials (ENMs) potentially leads to the release of multiple ENMs into the environment. However, previous efforts to understand the behavior and the risks associated with ENMs have focused on only one material at a time. In this study, the chemical interactions between two of the most highly used ENMs, nano-TiO2, and nano-ZnO, were examined in a natural water matrix. The fate of nano-ZnO in Lake Michigan water was investigated in the presence of nano-TiO2. Our experiments demonstrate that the combined effects of ZnO dissolution and Zn adsorption onto nano-TiO2 control the concentration of dissolved zinc. X-ray absorption spectroscopy was used to determine the speciation of Zn in the particulate fraction. The spectra show that Zn partitions between nano-ZnO and Zn2+ adsorbed on nano-TiO2. A simple kinetic model is presented to explain the experimental data. It integrates the processes of nano-ZnO dissolution with Zn adsorption onto nano-TiO2 and successfully predicts dissolved Zn concentration in solution. Overall, our results suggest that the fate and toxicity potential of soluble ENMs, such as nano-ZnO, are likely to be influenced by the presence of other stable ENMs, such as nano-TiO2.

Accumulation of anthropogenic litter (i.e. garbage; AL) and its ecosystem effects in marine environments are well documented. Rivers receive AL from terrestrial habitats and represent a major source of AL to marine environments, but AL is rarely studied within freshwater ecosystems. Our objectives were to 1) quantify AL density in urban freshwaters, 2) compare AL abundance among freshwater, terrestrial, and marine ecosystems, and 3) characterize the activity and composition of AL biofilms in freshwater habitats. We quantified AL from the Chicago River and Chicago's Lake Michigan shoreline, and found that AL abundance in Chicago freshwater ecosystems was comparable to previously reported data for marine and terrestrial ecosystems, although AL density and composition differed among habitats. To assess microbial interactions with AL, we incubated AL and natural substrates in 3 freshwater ecosystems, quantified biofilm metabolism as gross primary production (GPP) and community respiration (CR), and characterized biofilm bacterial community composition via high-throughput sequencing of 16S rRNA genes. The main driver of biofilm community composition was incubation location (e.g., river vs pond), but there were some significant differences in biofilm composition and metabolism among substrates. For example, biofilms on organic substrates (cardboard and leaves) had lower GPP than hard substrates (glass, plastic, aluminum and tiles). In addition, bacterial communities on organic substrates were distinct in composition from those on hard substrates, with higher relative abundances of bacteria associated with cellulose decomposition. Finally, we used our results to develop a conceptual diagram designed to unite the study of AL in terrestrial and freshwater environments with the well-established field of marine debris research. We suggest this broad perspective will be useful for future studies which synthesize AL sources, ecosystem effects, and fate across multiple ecosystem types, and will benefit management and reduction of global AL accumulations.

Connexin 30 (Cx30), a member of the large gap-junction protein family, plays a role in the homeostasis of the epidermis and inner ear through gap junctional intercellular communication (GJIC). Here, we investigate the underlying mechanisms of four autosomal dominant Cx30 gene mutations that are linked to hearing loss and/or various skin diseases. First, the T5M mutant linked to non-syndromic hearing loss formed functional gap junction channels and hemichannels, similar to wild-type Cx30. The loss-of-function V37E mutant associated with Clouston syndrome or keratitis-ichthyosis-deafness syndrome was retained in the endoplasmic reticulum and significantly induced apoptosis. The G59R mutant linked to the Vohwinkel and Bart-Pumphrey syndromes was retained primarily in the Golgi apparatus and exhibited loss of gap junction channel and hemichannel function but did not cause cell death. Lastly, the A88V mutant, which is linked to the development of Clouston syndrome, also significantly induced apoptosis but through an endoplasmic-reticulum-independent mechanism. Collectively, we discovered that four unique Cx30 mutants might cause disease through different mechanisms that also likely include their selective trans-dominant effects on coexpressed connexins, highlighting the overall complexity of connexin-linked diseases and the importance of GJIC in disease prevention.

Pipes that transport drinking water through municipal drinking water distribution systems (DWDS) are challenging habitats for microorganisms. Distribution networks are dark, oligotrophic and contain disinfectants; yet microbes frequently form biofilms attached to interior surfaces of DWDS pipes. Relatively little is known about the species composition and ecology of these biofilms due to challenges associated with sample acquisition from actual DWDS. We report the analysis of biofilms from five pipe samples collected from the same region of a DWDS in Florida, USA, over an 18 month period between February 2011 and August 2012. The bacterial abundance and composition of biofilm communities within the pipes were analyzed by heterotrophic plate counts and tag pyrosequencing of 16S rRNA genes, respectively. Bacterial numbers varied significantly based on sampling date and were positively correlated with water temperature and the concentration of nitrate. However, there was no significant relationship between the concentration of disinfectant in the drinking water (monochloramine) and the abundance of bacteria within the biofilms. Pyrosequencing analysis identified a total of 677 operational taxonomic units (OTUs) (3% distance) within the biofilms but indicated that community diversity was low and varied between sampling dates. Biofilms were dominated by a few taxa, specifically Methylomonas, Acinetobacter, Mycobacterium, and Xanthomonadaceae, and the dominant taxa within the biofilms varied dramatically between sampling times. The drinking water characteristics most strongly correlated with bacterial community composition were concentrations of nitrate, ammonium, total chlorine and monochloramine, as well as alkalinity and hardness. Biofilms from the sampling date with the highest nitrate concentration were the most abundant and diverse and were dominated by Acinetobacter.

Spinster homolog 2 (Spns2) acts as a Sphingosine-1-phosphate (S1P) transporter in zebrafish and mice, regulating heart development and lymphocyte trafficking respectively. S1P is a biologically active lysophospholipid with multiple roles in signalling. The mechanism of action of Spns2 is still elusive in mammals. Here, we report that Spns2-deficient mice rapidly lost auditory sensitivity and endocochlear potential (EP) from 2 to 3 weeks old. We found progressive degeneration of sensory hair cells in the organ of Corti, but the earliest defect was a decline in the EP, suggesting that dysfunction of the lateral wall was the primary lesion. In the lateral wall of adult mutants, we observed structural changes of marginal cell boundaries and of strial capillaries, and reduced expression of several key proteins involved in the generation of the EP (Kcnj10, Kcnq1, Gjb2 and Gjb6), but these changes were likely to be secondary. Permeability of the boundaries of the stria vascularis and of the strial capillaries appeared normal. We also found focal retinal degeneration and anomalies of retinal capillaries together with anterior eye defects in Spns2 mutant mice. Targeted inactivation of Spns2 in red blood cells, platelets, or lymphatic or vascular endothelial cells did not affect hearing, but targeted ablation of Spns2 in the cochlea using a Sox10-Cre allele produced a similar auditory phenotype to the original mutation, suggesting that local Spns2 expression is critical for hearing in mammals. These findings indicate that Spns2 is required for normal maintenance of the EP and hence for normal auditory function, and support a role for S1P signalling in hearing., Author Summary Progressive hearing loss is common in the human population but we know very little about the molecular mechanisms involved. Mutant mice are useful for investigating these mechanisms and have revealed a wide range of different abnormalities that can all lead to the same outcome: deafness. We report here our findings of a new mouse line with a mutation in the Spns2 gene, affecting the release of a lipid called sphingosine-1-phosphate, which has an important role in several processes in the body. For the first time, we report that this molecular pathway is required for normal hearing through a role in generating a voltage difference that acts like a battery, allowing the sensory hair cells of the cochlea to detect sounds at extremely low levels. Without the normal function of the Spns2 gene and release of sphingosine-1-phosphate locally in the inner ear, the voltage in the cochlea declines, leading to rapid loss of sensitivity to sound and ultimately to complete deafness. The human version of this gene, SPNS2, may be involved in human deafness, and understanding the underlying mechanism presents an opportunity to develop potential treatments for this form of hearing loss.

The influence of the synthesis conditions on the properties of nanocrystalline ZnS:Mn2+ is discussed. Different Mn2+ precursors and different ratios of the precursor concentrations [S2-]/[Zn2+] were used. The type of Mn2+ precursor does not have an effect on the luminescence properties in the synthesis method described. On going from an excess of [Zn2+] to an excess of [S2-] during the synthesis, the particle diameter increases from 3.7 to 5.1 nm, which is reflected by a change in the luminescence properties. Photoluminescence measurements also showed the absence of the ZnS defect luminescence around 450 nm when an excess [S2-] is used during the synthesis. This effect is explained by the filling of sulfur vacancies. The ZnS luminescence is quenched with an activation energy of 62 meV, which is assigned to the detrapping of a bound hole from such a vacancy.

Hand-assisted laparoscopic surgery (HALS) was developed to bridge the gap between open surgery and advanced laparoscopic surgery. Advantages of the hand in the abdomen include tactile feedback, the ability to palpate, blunt dissection, organ retraction, control of bleeding, and rapid organ removal. There are 3 commercially available devices in the United States, as well as a fourth in Europe and a fifth in Japan. Uses for HALS include procedures requiring intact specimen removal, complex laparoscopic procedures, preventing open conversion, and overcoming a technical obstacle. HALS procedures, such as esophagectomy, gastrectomy, hepatectomy, pancreatectomy, splenectomy, bariatric surgery, colectomy, nephrectomy, hysterectomy, and aortobifemoral bypass, have all been reported in the literature. Improvement in instrumentation, specifically with newer generation devices, will allow HALS to become more popular. We advocate the use of HALS specifically for laparoscopic colectomy, laparoscopic splenectomy for massive splenomegaly, and for living-related donor nephrectomy.

Three types of experiments were used to study the surface chemistry of silicon in alkaline solution: minority carrier injection from a p−n junction electrode, in-situ photoluminescence, and electron transfer to a redox system in solution. The results lead to the conclusion that the surface chemistry and electrochemistry are determined to a large extent by an activated intermediate of the chemical etching reaction of silicon with water. This novel coupling of chemical and electrochemical steps can account for some unusual features of the system, such as a mechanism for anodic oxidation and passivation based on electron injection and the strong influence of a weak oxidizing agent on the surface morphology of chemically etched silicon.

Measurements of the photoelectrochemical properties of nanocrystalline ZnS electrodes doped with Mn 2þ are presented and discussed. The observation of both anodic and cathodic photocurrent is direct evidence for the nanocrystalline nature of the system. In-situ photoluminescence measurements showed stable Mn 2þ related photoluminescence over a large potential range. Due to the unfavourable kinetics of electron and hole transfer across the interface between the nanocrystallites and solution, it is concluded that recombination accounts for most of the charge carriers generated by illumination. Breakdown of the ZnS into elementary Zn and S 2� in solution was also observed at negative potential. This breakdown introduces new non-radiative decay paths and is responsible for the slow luminescence decrease as a function of operating time.

Sickle cell disease is a hematological disorder with significant unmet need that affects approximately ten million people worldwide. Currently, treatment for SCD is limited to a single approved drug, Hydroxyurea, and palliative treatments such as hydration and pain management. The limited treatment options have led to considerable interest in developing new therapies for SCD. One strategy for a disease-modifying treatment for SCD is stabilization of the oxygenated form of hemoglobin (OxyHb) by a small molecule allosteric modulator (Zaugg et. Al, JBC, 1977). One such compound, Tucaresol was advanced into clinical trials on the strength of the pre-clinical data, however a SCD mouse model was unavailable when the trial was initiated. The renewed interest in stabilizing OxyHb with a small molecule presents an opportunity to use Tucaresol as a mechanism for understanding the translation between effects seen in an animal model and clinical endpoints in patients. In this study, we treated Townes SCD mice with Tucaresol for 15 days, to evaluate its effect on hematology, oxygen affinity, sickling and markers of inflammation in vivo. These results are compared to the clinical data reported in the original trials. Tucaresol is a substituted benzaldehyde derived from a class of molecules known to preferentially bind to hemoglobin and stabilize the oxygenated state by formation of a Schiff base linkage at a site on the a-chains (Rolan et. Al, Br. J. Clin. Pharm., 1995). Earlier molecules acting by this mechanism had been shown to reduce Hb S polymerization and RBC sickling in vitro, and it was theorized that long-term treatment with such molecules would impact hemolysis and occurrence of vaso-occlusive crisis (VOC) (Beddell et. Al, Br. J. Pharmac. 1984). Preclinical studies demonstrated Tucaresol modification of Hb S delays the polymerization process and inhibits RBC sickling. In clinical trials, Tucaresol positively impacted hematological markers including hemoglobin and reticulocyte counts, and reduced the percentage of irreversibly sickled cells. However, trials of Tucaresol were halted due to a significant immune response and specific inflammatory markers were not measured during the trial. To study these effects in Townes SCD model, mice were dosed with Tucaresol at 30 mg/kg twice a day, for fifteen days. The dose was selected to be consistent with clinical dosing regimens. Blood was collected prior to study start from individual animals to obtain baseline levels for hematological parameters and soluble cell adhesion molecules in plasma. Blood was sampled at day 3 and day 10 of dosing to understand drug exposure and accumulation. At this dose, Tucaresol demonstrated a steady state achieved by day 10 and the blood concentration ranged from 0.5-1.6 mM on day 15. Following two week dosing with Tucaresol, we observed a 50% increase in hemoglobin, and 24% increase in mean corpuscular hemoglobin concentration (MCHC), relative to vehicle treated animals. Reticulocytes, a clinical indicator of hemolytic anemia, are highly elevated in SCD patients and mice, also showed a 47% decrease in Tucaresol treated relative to vehicle treated animals. Oxygen affinity measurements showed a decrease in P50 and P20 values for treated animals, indicating increased oxygen affinity, consistent with the proposed mode of action of Tucaresol- stabilization of the oxygenated state. The percentage of sickled erythrocytes was also decreased by 38% in Tucaresol treated SCD mice when compared to vehicle controls. The decrease in sickling is consistent with the clinical observation of a 52% (mean) decrease in irreversibly sickled cells. In contrast to the improvement seen with hematological parameters, inflammatory markers remained either unchanged or slightly elevated after 15 days of treatment with Tucaresol. Plasma levels of sICAM-1 and sVCAM-1 were unchanged while sE-Selectin was elevated. In summary, in this short course of treatment of SCD mice, Tucaresol had an impact on the hematological markers that was consistent with effects observed in the clinic, but did not modulate the inflammation response. All experiments were within guidelines and were reviewed and approved by Pfizer institutional animal care and use committee. Disclosures Knee: Pfizer Inc: Employment. Jasuja:Pfizer: Employment. Barakat:Pfizer: Employment. Kelly:Pfizer: Employment. Singh:Pfizer Inc: Employment. Janz:Pfizer: Employment.

It is shown that the (0 0 0 1) Ga-polar surface of highly doped GaN single crystals can be etched anodically in the dark in dilute aqueous KOH solution. Two etching regimes involving electron tunneling and avalanche breakdown are defined. The electrochemistry and surface morphology encountered in each regime are described. Possible applications of anodic etching are considered.

Nanocrystalline ZnS:Pb2+ is synthesised ia a precipitation method. The influence of the size of the nanocrystals and the sulfide concentration used in the synthesis on the luminescence properties is investigated. Nanocrystalline ZnS:Pb2+ shows a white emission under UV excitation with a rather high quantum efficiency (∽5%). At least two luminescence centres are involved. One centre is identified as a Pb2+ ion located on a regular Zn2+ site and gives a red emission under 480 nm excitation. The luminescence properties of this emission are characteristic of 3P0 → 1S0 (A-band) or charge transfer (D-band) transitions on Pb2+ ions. The other centres are not as well defined and give a broad green emission band under 380 nm excitation and also show luminescence properties typically observed for Pb2+. The green emission probably originates from a charge-transfer like D-band emission of Pb2+ in ZnS close to a defect (e.g. an S2− vacancy or an O2− ion on an S2− site). A relation between the temperature quenching of the emissions and the band gap is observed and indicates that photoionisation occurs. The higher quenching temperature for the Pb2+ luminescence in smaller particles can be explained by widening of the band gap as a result of quantum size effects in the ZnS host.

This paper describes the application of a novel etch-stop technique, based on galvanic element formation, to the fabrication of micromechanical sensors. The theory of operation in tetramethyl ammonium hydroxide (TMAH) and hydrofluoric acid (HF) solutions is discussed, together with the main limitations. A number of devices are presented. These include a piezoresistive pressure sensor made with a galvanic etch stop in a 25% TMAH solution at 80 °C and the contactless fabrication in similar solutions of a vibration sensor based on free-standing crystalline silicon beams. The thickness definition and uniformity were found to be poorer with the cantilever than with the membrane type sensors. Oxygen in the solution was used to provide the cell current, which was therefore rather low. This resulted in a low package density of the sensor elements on the wafer. Free-standing thick polysilicon structures were also formed with a galvanic etch-stop technique in HF solutions. The selectivity of this process, and the thickness definition and uniformity were good. In these solutions, the cell current could be easily increased by adding other strong oxidizing agents, such as hydrogen peroxide. Therefore, high package densities could be achieved in these solutions.

The effect of oxidizing agents (MnO4− and CrO42−) on the electrochemistry, etching kinetics and etching morphology of p-type silicon in KOH solution has been studied. Electrochemical results show that reduction of MnO4− occurs via hole injection into the valence band of oxide-covered silicon, while the rate of cathodic reduction of CrO42− is very low. The current density measured with MnO4− at negative potential drops to a low value when the surface oxide is removed and chemical etching starts. It is suggested that during etching, a surface intermediate is formed which can interact chemically with the oxidizing agents. This is confirmed by optical absorption measurements. At potentials positive with respect to the open circuit potential both oxidizing agents modify the formation of surface oxide. In addition, both oxidizing agents influence the surface morphology by ‘preventing’ pyramid formation. These results are discussed in terms of a model previously suggested for chemical etching of silicon in alkaline solutions.

The charge carrier dynamics in illuminated nanoporous ZnO electrodes consisting of 5 nm particles were investigated. Stable photocurrent quantum efficiencies of 15−30% and photovoltages of up to 0.4 V were found in the presence of the I-/I3- redox couple in propylene carbonate. The electronic transport in these ZnO electrodes was fast, the tunneling of electrons from the ZnO particles to the conducting substrate was much slower. The photovoltage as a function of light intensity showed a clear discontinuity. This was related to the indirect recombination kinetics; under open circuit conditions it could take 10 s or longer before a photogenerated electron was transferred to I3- in solution.

Colloidal CdSe quantum dots were chemisorbed on a gold electrode using a variety of self-assembled monolayers (SAMs) consisting of dithiols and rigid disulfides. After absorption of a photon with an energy larger than the band gap, a long-lived excited state is formed in the quantum dot; this state can decay by electron tunneling via the gold. The rate of photoinduced tunneling was measured directly by intensity-modulated photocurrent spectroscopy (IMPS), and its distance dependence was studied using rigid SAMs separating the Q-CdSe and Au. The tunneling rate was found to depend exponentially on the distance, with a decay length of 2 A.

Objective: Aortobifemoral bypass grafting is a durable operation for arterial reconstruction in patients with symptomatic aortoiliac occlusive disease. In several small laparoscopic series technically demanding aortic operations have been described that have not gained widespread acceptance or applicability. To simplify the laparoscopic approach to the aorta, we have developed a technique of aortobifemoral bypass grafting that uses hand-assisted laparoscopic surgery (HALS) to minimize the complexity of aortic dissection and reconstruction. Methods: Five patients with symptomatic aortoiliac occlusive disease underwent successful HALS aortobifemoral bypass grafting. With the use of a specialized sleeve device (Hand-Port), an operative hand was introduced into the laparoscopic field while pneumoperitoneum was maintained. Laparoscopic dissection of the infrarenal aorta was then performed with retraction provided by the operative hand. Proximal aortic anastomosis was performed with an open technique through the same 7.5-cm Hand-Port incision, and femoral anastomoses were performed in the standard fashion. Results: Five hand-assisted laparoscopic aortobifemoral bypass grafts were performed (two end-to-end, three end-to-side proximal anastomoses). Mean operative time was 231 minutes. Mean blood loss was 440 mL. All patients underwent extubation immediately after surgery, were ambulatory on postoperative day (POD) 1, and were tolerating their diet by POD 3. The mean length of hospital stay was 3.8 days. One patient was discharged on POD 5 and started a clear liquid diet after a self-limiting postoperative ileus. All patients were asymptomatic and back to full activity/work by 14.6 days postoperatively, on average (range, 11-20 days). Conclusion: The HALS offers the advantages of tactile feedback, flexible retraction, and the introduction of conventional surgical instruments, all of which extend laparoscopic surgery and its established benefits to a wide array of more complex surgical problems, including major vascular surgery. Ease of performance, shorter hospital stays, and faster recovery times all suggest that HALS may become a valuable adjunct to conventional aortobifemoral bypass grafting. (J Vasc Surg 2000;31:1142-8.)

When p-type silicon is contacted to a noble metal in HF solution containing an oxidizing agent, a galvanic cell can be formed. The oxidizing agent is reduced at the metal and the semiconductor is etched. To achieve a similar effect with n-type silicon, illumination is required. On the other hand, a galvanic cell is formed with both n- and p-type silicons in alkaline solution in the dark. These results are explained on the basis of silicon electrochemistry with the use of energy band diagrams. It is shown that “galvanic etching” can be used to control the silicon surface morphology, e.g., to form microporous or macroporous layers or produce pyramid-free anisotropic structures.

The electronic structure and decay dynamics of a long-lived photoexcited state in PbS quantum dots (QD), adsorbed as a monolayer on a gold electrode, were studied by a time resolved photoelectrochemical technique, intensity-modulated photocurrent spectroscopy (IMPS). By scanning the Fermi level of the gold, we found that the excited state consists of an electron in a deep trap and a hole in the HOMO. The rate constants of photoinduced electron tunneling between the dots and the electrode and between the dots and the electrolyte were determined. It was found that the trapped charge carrier has a lower tunneling probability than the free charge carrier, indicating that distance is the determining parameter for electron tunneling.

One of the major advances in the understanding of polyneuropathies during the past decade has been the realization that plasma cell dyscrasias (PCD) and their accompanying monoclonal proteins (M-protein) are frequently associated with neuromuscular diseases. These syndromes may be distinctive and, in several cases, appear to be caused by the direct effects of the serum immunoglobulins on peripheral nerves. Monoclonal proteins have been found, for instance, to react with a variety of neuronal antigens found in myelin sheaths and axonal membranes. Some forms of motor neuron disease may possibly be related to the effects of serum immunoglobulins. These syndromes are important for several reasons. First, several are potentially treatable by modern immunotherapy aimed at lowering the M-protein concentration in serum. Second, they offer a rare glimpse at the mechanism of autoimmune polyneuropathies. Because the immunoglobulin is recognizable, can be isolated, and its target antigen has been identified, the mechanism of nerve fiber damage can be studied more directly in many cases. This opportunity for study will undoubtedly lead to a better understanding of the immunopathogenesis of autoimmune neuropathies, including those in which the immune effectors are presently not known. This article reviews the rapidly developing field of the polyneuropathies associated with monoclonal gammopathies of undetermined significance (MGUS). It offers a framework for an approach to these patients.

Well-defined polycrystalline Cu2O was electrodeposited on transparent conducting substrates from alkaline Cu(II) lactate solutions. The morphology of the layers could be controlled by choosing the appropriate experimental conditions; the pH and temperature of the deposition solution were especially important. The growth of the oxide involves a thermally activated process, for which an activation energy of 0.8 eV was found. A mechanism for the deposition is proposed. The optical absorption of the electrodeposited oxide in the visible range was much weaker than expected for a direct semiconductor with a band gap of 2.0 eV. Finally, we show that it is possible to grow Cu2O inside an n-type TiO2 nanoporous matrix.

We have modeled the switching behavior of a twisted nematic cell using the one-dimensional Ericksen–Leslie equations of nematodynamics. We compare the modeling results with experimental data on transmission versus time. Excellent agreement between experiment and model is achieved at all voltages and viewing angles. To achieve this agreement, only two viscosity parameters are required; these are combinations of the Leslie viscosity coefficients, namely, α3−α2 (the rotational viscosity) and α4+α5. A fast and stable adaptive numerical algorithm, based on an effective viscosity parameter, is developed for solving the equations of motion. The viscosity parameters obtained from fitting the flow experiments are in good agreement with those obtained from dynamic light-scattering measurements.

The electrochemical properties of highly doped p-type single crystalline diamond electrodes (100 and 110 oriented) in aqueous electrolytes were investigated. The interfacial capacitance obeys the Mott–Schottky relationship in a considerable potential range and can be assigned to a depletion layer in the diamond. The energetic position of the valence band edge is about 4 and 2 V versus SHE for (100) and (110) oriented diamond respectively. Oxygen and hydrogen evolution occur at large overpotentials (1 V) in agreement with previous results reported for polycrystalline diamond. Interestingly, with reversible redox systems, metal-type redox kinetics around the equilibrium potential are observed. The mechanism of electron exchange between the valence band of diamond and simple redox systems was investigated in detail using electrochemical impedance spectroscopy. A quantitative model is proposed, that assumes that electron exchange is mediated by bandgap states.

Extraocular muscle weakness is the most common presenting sign of myasthenia gravis (MG). More than half of patients presenting with symptoms isolated to these muscles (OMG) develop generalized myasthenia gravis (GMG) over the course of their illness. No clinical, laboratory, or electrophysiological features are recognized that identify these high-risk patients. We have therefore assessed the ability of single-fiber electromyography (SFEMG) to predict the development of GMG in patients presenting with OMG. Thirty-nine consecutive patients presenting with OMG underwent SFEMG of the extensor digitorum communis muscle as well as a battery of other laboratory and imaging studies at the time of diagnosis. All patients were followed prospectively for a minimum of 24 months or until they developed GMG. Two patients were excluded, leaving 37 for assessment. Twenty remained with pure OMG for the entire follow-up period (mean, 55 months). Twenty-six of the 37 had abnormal SFEMG studies at presentation. Eleven of these remained with OMG and 15 developed GMG. Fifty-eight percent of patients with an abnormal SFEMG developed GMG, whereas 82% of those with a normal study remained with OMG. Thus, a normal SFEMG was associated with MG remaining restricted to the extraocular muscles. (P = 0.036, Fisher's exact test), but an abnormal SFEMG was not predictive of subsequent development of GMG.

Soil microcosms each consisting of approximately 20 kg soil were set up in the laboratory. Three microcosms were amended with 6000 mg zinc kg−1, a concentration chosen to approximate the quantities of total zinc found at a contaminated field site. Three control microcosms received no zinc amendment. Three pH control microcosms received H2SO4, adequate to result in the same pH decrease as occurred in the zinc amended soil. Mean soluble zinc contents were 4660 mg kg−1 (amended soils), 1.08 mg kg−1 (unamended soils), and 2.10 mg kg−1 (pH adjusted soils). Biological community assessments included culturable bacteria (plate counts), microbial biomass (chloroform fumigation), dehydrogenase activity, proportion of zinc resistant bacteria (plate counts on zinc amended agar), and changes in community structure (BIOLOG and phospholipid fatty acid (PLFA) analysis). After 15 d of incubation, zinc amendment resulted in an 87% decrease in viable counts and a 47% decrease in microbial biomass. Dehydrogenase activity decreased by 95%, and the proportion of zinc resistant bacteria increased from 0.08% to 0.75%. Microbial community structure alteration resulting from zinc amendment was indicated by shifts in both BIOLOG metabolic profiles and PLFA profiles. Effects of zinc on PLFA profiles included relative decreases in indicator fatty acids for arbuscular mycorrhizal fungi and actinomycetes. Some adaptation of the microbial communities to the zinc amendment was suggested by the fact that after 420 d incubation there were no significant differences in culturable bacterial populations or microbial biomass of the control and zinc amended systems. However, other microbial properties measured in this study showed that zinc still affected microbial community structure and activity after 420 d. Dehydrogenase activity of the zinc treated communities remained 93% lower than the controls. The percentage of zinc resistant populations was still significantly higher for the zinc treated communities. Similarly, the BIOLOG and PLFA profiles continued to show differences in the structure of the zinc treated and control microbial communities. Effects of zinc on PLFA profiles at day 420 included a relative decrease in an indicator fatty acid for arbuscular mycorrhizal fungi and a relative increase in an indicator fatty acid for fungi. The comparison of PLFA profiles also showed mixed results for several fatty acid indicators for actinomycetes. The pH control treatment showed similar effects on population size and activity as the zinc treatment, although in most cases there was a much stronger effect with the zinc treatment. In addition, the pH treatment caused changes in BIOLOG and PLFA profiles which were different than the changes seen with zinc treatment.

Porous silicon is usually formed under anodic polarization in an electrochemical cell. In this paper, a technique is described for forming porous silicon without using an external current or voltage source. By connecting an inert metal electrode to a silicon sample, both immersed in a HF solution, a galvanic cell is formed. Reduction of oxygen at the inert electrode results in the etching of Si at the silicon/electrolyte interface. Porous silicon is formed at a rate which is dependent on the cell current. The formation rate may be enhanced by adding oxidizing agents to the solution. Galvanic etching for forming porous Si is a promising alternative for stain etching since it gives more uniform and reproducible results.

The electronic structure and decay dynamics of a long-lived excited state in CdS quantum dots (Q-CdS) were investigated in a novel way by a time-resolved optoelectrical method. Q-CdS was adsorbed a...

1. Brachial artery infusion of endothelin (ET)-1 causes transient vasodilatation followed by sustained vasoconstriction of the forearm vascular bed, whereas ET-1 antagonists cause sustained vasodilatation. These data suggest that ET-1 contributes to basal vascular tone. 2. Systemic infusion of ET-1 increases blood pressure and total peripheral vascular resistance and reduces heart rate and cardiac output. The renal and pulmonary circulations are particularly sensitive to the vasoconstrictor effects of ET-1. Systemic infusion of the ETA/B receptor antagonist TAK-044 reduces mean arterial pressure and peripheral vascular resistance. 3. Plasma ET-1 concentrations are not elevated in essential hypertension; however, insulin resistance may be a major determinant of plasma ET-1 concentrations. Vascular sensitivity to ET-1 is normal or may be increased in essential hypertension. 4. Plasma ET-1 concentrations are increased in moderate and severe heart failure and are correlated with clinical and haemodynamic measures of severity. Endothelin-1 contributes to increased vascular tone in cardiac failure. 5. Plasma ET-1 concentrations increase following myocardial infarction and persistent elevation predicts an increased mortality within the subsequent 12 months. 6. Preliminary data suggest that interventions that reduce the activity of the endothelin system may have a beneficial effect in heart failure and myocardial infarction.

1. In humans, the hypertensive effects of adrenocorticotropic hormone (ACTH) infusion are reproduced by intravenous or oral cortisol. Oral cortisol increases blood pressure in a dose-dependent fashion. At a dose of 80-200 mg/day, the peak increases in systolic pressure are of the order of 15 mmHg. Increases in blood pressure are apparent within 24 h. 2. Cortisol-induced hypertension is accompanied by a significant sodium retention and volume expansion. Co-administration of the type I (mineralocorticoid) receptor antagonist spironolactone does not prevent the onset of cortisol-induced hypertension. Thus, sodium retention is not the primary mechanism of cortisol-induced hypertension. 3. Direct and indirect measures of sympathetic activity are unchanged or suppressed during cortisol administration, suggesting that cortisol-induced hypertension is not mediated by increased sympathetic tone. 4. Preliminary evidence in humans suggests that suppression of the nitric oxide system may play a role in cortisol-induced hypertension. 5. These potential mechanisms of cortisol action may be relevant in a number of clinical contexts, including Cushing's syndrome, apparent mineralocorticoid excess, the hypertension of liquorice abuse and chronic renal failure. There is also preliminary evidence suggesting a role for cortisol in essential hypertension.

Pulmonary endothelium forms a semiselective barrier that regulates fluid balance and leukocyte trafficking. During the course of lung inflammation, neurohumoral mediators and oxidants act on endothelial cells to induce intercellular gaps permissive for transudation of proteinaceous fluid from blood into the interstitium. Intracellular signals activated by neurohumoral mediators and oxidants that evoke intercellular gap formation are incompletely understood. Cytosolic Ca2+concentration ([Ca2+]i) and cAMP are two signals that importantly dictate cell-cell apposition. Although increased [Ca2+]ipromotes disruption of the macrovascular endothelial cell barrier, increased cAMP enhances endothelial barrier function. Furthermore, during the course of inflammation, elevated endothelial cell [Ca2+]idecreases cAMP to facilitate intercellular gap formation. Given the significance of both [Ca2+]iand cAMP in mediating cell-cell apposition, this review addresses potential sites of cross talk between these two intracellular signaling pathways. Emerging data also indicate that endothelial cells derived from different vascular sites within the pulmonary circulation exhibit distinct sensitivities to permeability-inducing stimuli; that is, elevated [Ca2+]ipromotes macrovascular but not microvascular barrier disruption. Thus this review also considers the roles of [Ca2+]iand cAMP in mediating site-specific alterations in endothelial permeability.