Structural and optical properties of graphene oxide prepared by modified hummers' method

Graphene oxide was synthesized from graphite flakes using modified Hummers' method. The interlayer spacings of graphite, graphite oxide and graphene oxide were measured using X-ray diffraction technique. The C/O atomic ratios of graphite oxide and graphene oxide were calculated from XPS measurements. The transformation of graphite to graphite oxide and finally to graphene oxide was clearly observed from the micro-Raman spectroscopy data and was confirmed from the FESEM micrographs. UV-VIS-NIR spectrophotometer was used to study the absorbance of graphene oxide and reduced graphene oxide samples. Finally, the chemically reduced graphene oxide was heat-treated in air to obtain chemically modified graphene

Helicobacter species are associated with possible increase in risk of biliary lithiasis and benign biliary diseases

<p>Abstract</p> <p>Background</p> <p>Hepato-biliary tract lithiasis is common and present either as pain or as asymptomatic on abdominal ultrasonography for other causes. Although the DNA of <it>Helicobacter </it>species are identified in the gallbladder bile, tissue or stones analyzed from these cases, still a causal relationship could not be established due to different results from different geographical parts.</p> <p>Methods</p> <p>A detailed search of pubmed and pubmedcentral was carried out with key words <it>Helicobacter </it>and gallbladder, gallstones, hepaticolithiasis, cholelithiasis and choledocholithiasis, benign biliary diseases, liver diseases. The data was entered in a data base and meta analysis was carried out. The analysis was carried out using odds ratio and a fixed effect model, 95% confidence intervals for odds ratio was calculated. Chi square test for heterogeneity was employed. The overall effect was calculated using Z test.</p> <p>Results</p> <p>A total of 12 articles were identified. One study used IgG for diagnosis while others used the PCR for Ure A gene, 16 S RNA or Cag A genes. A couple of studies used culture or histopathology besides the PCR. The cumulative results show a higher association of <it>Helicobacter </it>with chronic liver diseases (30.48%), and stone diseases (42.96%)(OR 1.77 95% CI 1.2–2.58; Z = 2.94, p = 0.003), the effect of each could not be identified as it was difficult to isolate the effect of helicobacter due to mixing of cases in each study.</p> <p>Conclusion</p> <p>The results of present meta analysis shows that there is a slight higher risk of cholelithiasis and benign liver disease (OR 1.77), however due to inherent inability to isolate the effect of stone disease from that of other benign lesions it is not possible to say for sure that <it>Helicobacter </it>has a casual relationship with benign biliary disease or stone disease or both.</p

In situ observation of oscillatory redox dynamics of copper

How a catalyst behaves microscopically under reaction conditions, and what kinds of active sites transiently exist on its surface, is still very much a mystery to the scientific community. Here we present an in situ study on the red-ox behaviour of copper in the model reaction of hydrogen oxidation. Direct imaging combined with on-line mass spectroscopy shows that activity emerges near a phase boundary, where complex spatio-temporal dynamics are induced by the competing action of simultaneously present oxidizing and reducing agents. Using a combination of in situ imaging with in situ X-ray absorption spectroscopy and scanning photoemission microscopy, we reveal the relation between chemical and morphological dynamics and demonstrate that a static picture of active sites is insufficient to describe catalytic function of redox-active metal catalysts. The observed oscillatory redox dynamics provide a unique insight on phase-cooperation and a convenient and general mechanism for constant re-generation of transient active sites

You Mate, I Mate: Macaque Females Synchronize Sex not Cycles

Extended female sexuality in species living in multimale-multifemale groups appears to enhance benefits from multiple males. Mating with many males, however, requires a low female monopolizability, which is affected by the spatiotemporal distribution of receptive females. Ovarian cycle synchrony potentially promotes overlapping receptivity if fertile and receptive periods are tightly linked. In primates, however, mating is often decoupled from hormonal control, hence reducing the need for synchronizing ovarian events. Here, we test the alternative hypothesis that females behaviorally coordinate their receptivity while simultaneously investigating ovarian cycle synchrony in wild, seasonal Assamese macaques (Macaca assamensis), a promiscuous species with extremely extended female sexuality. Using fecal hormone analysis to assess ovarian activity we show that fertile phases are randomly distributed, and that dyadic spatial proximity does not affect their distribution. We present evidence for mating synchrony, i.e., the occurrence of the females' receptivity was significantly associated with the proportion of other females mating on a given day. Our results suggest social facilitation of mating synchrony, which explains (i) the high number of simultaneously receptive females, and (ii) the low male mating skew in this species. Active mating synchronization may serve to enhance the benefits of extended female sexuality, and may proximately explain its patterning and maintenance

WriteSim TCExam - An open source text simulation environment for training novice researchers in scientific writing

BACKGROUND: The ability to write clearly and effectively is of central importance to the scientific enterprise. Encouraged by the success of simulation environments in other biomedical sciences, we developed WriteSim TCExam, an open-source, Web-based, textual simulation environment for teaching effective writing techniques to novice researchers. We shortlisted and modified an existing open source application - TCExam to serve as a textual simulation environment. After testing usability internally in our team, we conducted formal field usability studies with novice researchers. These were followed by formal surveys with researchers fitting the role of administrators and users (novice researchers) RESULTS: The development process was guided by feedback from usability tests within our research team. Online surveys and formal studies, involving members of the Research on Research group and selected novice researchers, show that the application is user-friendly. Additionally it has been used to train 25 novice researchers in scientific writing to date and has generated encouraging results. CONCLUSION: WriteSim TCExam is the first Web-based, open-source textual simulation environment designed to complement traditional scientific writing instruction. While initial reviews by students and educators have been positive, a formal study is needed to measure its benefits in comparison to standard instructional methods

Helicobacter species in cancers of the gallbladder and extrahepatic biliary tract

Helicobacter species have been found in human bile and biliary tract (BT) tissue and are suspected to cause BT diseases, including gallbladder and extrahepatic cancers, collectively referred to in this work as BT cancers. We conducted a literature review of the epidemiological evidence linking the presence of Helicobacter species in bile or BT biopsies to BT cancers and benign diseases. Reports showed great variability with respect to study methods. Nine studies of BT cancers were identified, all with 30 or fewer BT cancers; eight included cancer-free control subjects and used polymerase chain reaction (PCR) as a means of Helicobacter species detection. In four of these studies, Helicobacter species were detected in patients with BT cancer significantly more frequently than in controls, at least when controls without BT diseases were used. In two studies, no Helicobacter species were detected in either cases or controls. Helicobacter species were also often detected in benign BT diseases such as gallstone disease or chronic cholecystitis. As our current knowledge relies on a few small studies that showed substantial differences, larger studies and more standardised protocols for detecting DNA and antibodies against Helicobacter species are needed to investigate a potential association with BT cancer

Hemodialysis Removes Uremic Toxins That Alter the Biological Actions of Endothelial Cells

Chronic kidney disease is linked to systemic inflammation and to an increased risk of ischemic heart disease and atherosclerosis. Endothelial dysfunction associates with hypertension and vascular disease in the presence of chronic kidney disease but the mechanisms that regulate the activation of the endothelium at the early stages of the disease, before systemic inflammation is established remain obscure. In the present study we investigated the effect of serum derived from patients with chronic kidney disease either before or after hemodialysis on the activation of human endothelial cells in vitro, as an attempt to define the overall effect of uremic toxins at the early stages of endothelial dysfunction. Our results argue that uremic toxins alter the biological actions of endothelial cells and the remodelling of the extracellular matrix before signs of systemic inflammatory responses are observed. This study further elucidates the early events of endothelial dysfunction during toxic uremia conditions allowing more complete understanding of the molecular events as well as their sequence during progressive renal failure

Potential therapeutic applications of microbial surface-activecompounds

Numerous investigations of microbial surface-active compounds or biosurfactants over the past two decades have led to the discovery of many interesting physicochemical and biological properties including antimicrobial, anti-biofilm and therapeutic among many other pharmaceutical and medical applications. Microbial control and inhibition strategies involving the use of antibiotics are becoming continually challenged due to the emergence of resistant strains mostly embedded within biofilm formations that are difficult to eradicate. Different aspects of antimicrobial and anti-biofilm control are becoming issues of increasing importance in clinical, hygiene, therapeutic and other applications. Biosurfactants research has resulted in increasing interest into their ability to inhibit microbial activity and disperse microbial biofilms in addition to being mostly nontoxic and stable at extremes conditions. Some biosurfactants are now in use in clinical, food and environmental fields, whilst others remain under investigation and development. The dispersal properties of biosurfactants have been shown to rival that of conventional inhibitory agents against bacterial, fungal and yeast biofilms as well as viral membrane structures. This presents them as potential candidates for future uses in new generations of antimicrobial agents or as adjuvants to other antibiotics and use as preservatives for microbial suppression and eradication strategies