Enhanced photocatalytic activity of tin oxide-doped molybdenum disulfide nanohybrids under visible light irradiation: Antibiotics elimination, heavy metal reduction and antibacterial behavior

Nano-heterojunction photocatalytic can operate removal of pollutants, which is basic for the sustainable development of a clean environment. Herein, we propose a novel MoS2/SnO2 (MS) S-scheme heterojunction by a facile hydrothermal process, which is cheap, easily available, highly visible-light response, and good stability. The MS nano-heterojunction suggested superior performance with the photocatalytic degradation of 97.6% within 100 min for ciprofloxacin (CIP) removal, which was 5.74 and 4.88 folds higher than that of pristine MoS2 and SnO2, respectively. The fabricated MS photocatalysts displayed outstanding photocatalytic efficiency toward Cr (VI) reduction. The removal capability of Cr (VI) reached up to 92.5% within 60 min. The photodegradation efficiency was 5.2 folds that of pristine MoS2. In addition, the antibacterial performance approximately approached 100% for E. coli within 10 min, which was more apparent than the others. A series of excellent results implied that MS nano-heterojunction had a high ultraviolet and visible light absorbance, larger specific surface area, outstanding electron-hole pairs migration and higher capability of photo-response electrons and holes separation rate. This system offers a novel window into the evolution of nano-heterojunction for wastewater treatment and solar energy harvesting applications.

A novel tungsten diselenide nanoparticles for enhanced photocatalytic performance of Cr (VI) reduction and ciprofloxacin (CIP)

Nanoparticles (NPs) fabrication is a significant approach to enhance the visible light response of photocatalysts, to realize inexpensive and more harmful compound removal, at larger scale. The poor electrons and holes separation capability and low light activity of bulk materials can be notably enhanced through developing NPs. From photocatalytic investigation, better performance was received in the tungsten diselenide (WSe2) NPs than that in bare WSe2, exhibiting the action of restrained recombination of charge carriers in the NPs. The photocatalytic Cr(VI) reduction efficiency of WSe2 NPs is 2.7 folds greater than that by bare WSe2. On the other hand, the photocatalytic efficiency follows the order of nano WSe2-3 > nano WSe2-2 > nano WSe2-1 > bare WSe2, nano WSe2-3 is nearly 2.7 folds greater than that of bare WSe2. The results imply the fabrication of WSe2 NPs and it possesses improved visible light utilization. The proposed WSe2 NPs have merged with the three aspects of photocatalytic capability including the visible light activity, the valid separation of photo-response charge carriers and enough surface active sites owing to the nanoscale formed. This research endows conduct on the potential style of NPs for photo-response water environmental remediation.

Z-Scheme MoS2/TiO2/graphene nanohybrid photocatalysts for visible light-induced degradation for highly efficient water disinfection and antibacterial activity

A new Z-scheme MoS2/TiO2/graphene nanohybrid effectively degraded antibiotics, heavy metals and microorganisms under visible irradiation.

Spatial analysis and mapping of child malnutrition in Burkina Faso

Background

Approximately 45% of all child deaths are associated with malnutrition in sub-Saharan Africa. However, information on the geographical variations of child malnutrition in Burkina Faso is limited. This study examined the geographical distribution and the community characteristics associated with child malnutrition in Burkina Faso using spatial regression analysis.

Methods

Data from the 2011 Burkina Faso Demographic Health Survey were analyzed. A representative sample of 572 communities and 6,120 children under age of five were in the survey. A general Kriging interpolation method was used to generate spatial malnutrition patterns. The Local Indicator of Spatial Autocorrelation was used to identify particular communities clustering with high and low child malnutrition scores. In the spatial regression analysis, we used a two-step procedure combining generalized estimating equation models (GEE) and spatial lag modeling techniques.

Results

The average rates of stunting and wasting were 32.48%, and 15.05%, respectively. Stunting hotspots were observed to be in the eastern and northeastern part of Burkina Faso (i.e. Oudolan, Séno), while high rates of wasting were observed in the central-north part. The results of the spatial regression analysis revealed lower stunting rates in communities with a higher percentage of households with improved sanitation. Communities with higher rates of professionally assisted births were associated with low wasting rates while communities with higher rates of households with low wealth index reported higher rates of wasting. Spatial lag models appeared to estimate the relationship between community-level risk factors and stunting and wasting more accurately than the ordinary least squares models.

Conclusions

This study revealed significant geographical patterns and community factors associated with childhood malnutrition. These factors should be considered for future programs aiming at reducing child malnutrition in Burkina Faso.

Key messages

The study identifies spatial trends and contextual factors associated with child malnutrition in Burkina Faso. Public health programs should focus on the regions identified as hot spots of child malnutrition in Burkina Faso.

Weak anti-localization of two-dimensional holes in germanium beyond the diffusive regime

Gate-controllable spin-orbit coupling is often one requisite for spintronic devices. For practical spin field-effect transistors, another essential requirement is ballistic spin transport, where the spin precession length is shorter than the mean free path such that the gate-controlled spin precession is not randomized by disorder. In this letter, we report the observation of a gate-induced crossover from weak localization to weak anti-localization in the magneto-resistance of a high-mobility two-dimensional hole gas in a strained germanium quantum well. From the magneto-resistance, we extract the phase-coherence time, spin-orbit precession time, spin-orbit energy splitting, and cubic Rashba coefficient over a wide density range. The mobility and the mean free path increase with increasing hole density, while the spin precession length decreases due to increasingly stronger spin-orbit coupling. As the density becomes larger than ∼6 × 1011 cm-2, the spin precession length becomes shorter than the mean free path, and the system enters the ballistic spin transport regime. We also report here the numerical methods and code developed for calculating the magneto-resistance in the ballistic regime, where the commonly used HLN and ILP models for analyzing weak localization and anti-localization are not valid. These results pave the way toward silicon-compatible spintronic devices.

Density-controlled quantum Hall ferromagnetic transition in a two-dimensional hole system

Quantum Hall ferromagnetic transitions are typically achieved by increasing the Zeeman energy through in-situ sample rotation, while transitions in systems with pseudo-spin indices can be induced by gate control. We report here a gate-controlled quantum Hall ferromagnetic transition between two real spin states in a conventional two-dimensional system without any in-plane magnetic field. We show that the ratio of the Zeeman splitting to the cyclotron gap in a Ge two-dimensional hole system increases with decreasing density owing to inter-carrier interactions. Below a critical density of ~2.4 × 10¹⁰ cm⁻², this ratio grows greater than 1, resulting in a ferromagnetic ground state at filling factor ν = 2. At the critical density, a resistance peak due to the formation of microscopic domains of opposite spin orientations is observed. Such gate-controlled spin-polarizations in the quantum Hall regime opens the door to realizing Majorana modes using two-dimensional systems in conventional, low-spin-orbit-coupling semiconductors.

High-mobility capacitively-induced two-dimensional electrons in a lateral superlattice potential

In the presence of a lateral periodic potential modulation, two-dimensional electrons may exhibit interesting phenomena, such as a graphene-like energy-momentum dispersion, Bloch oscillations, or the Hofstadter butterfly band structure. To create a sufficiently strong potential modulation using conventional semiconductor heterostructures, aggressive device processing is often required, unfortunately resulting in strong disorder that masks the sought-after effects. Here, we report a novel fabrication process flow for imposing a strong lateral potential modulation onto a capacitively induced two-dimensional electron system, while preserving the host material quality. Using this process flow, the electron density in a patterned Si/SiGe heterostructure can be tuned over a wide range, from 4.4 × 10(10) cm(-2) to 1.8 × 10(11) cm(-2), with a peak mobility of 6.4 × 10(5) cm(2)/V·s. The wide density tunability and high electron mobility allow us to observe sequential emergence of commensurability oscillations as the density, the mobility, and in turn the mean free path, increase. Magnetic-field-periodic quantum oscillations associated with various closed orbits also emerge sequentially with increasing density. We show that, from the density dependence of the quantum oscillations, one can directly extract the steepness of the imposed superlattice potential. This result is then compared to a conventional lateral superlattice model potential.

Using mathematical models to understand the time dependence of the growth of ductal carcinoma in situ

Abstract #1165

Background: Models of cancer growth have been developed that predict tumor size and growth dynamics for invasive tumors. However, it has been difficult to model ductal carcinoma in situ (DCIS) because of the constraints introduced by its containment within the duct system.
 Materials and Methods: We have developed a spherical model of growth of solid type DCIS using chemical engineering models of reaction and diffusion in porous media to represent the spread of DCIS in the duct systems. The model predicts tumor diameter based on four input parameters: the ratio of the apoptosis rate to the proliferation rate (A), the diffusion penetration length for nutrient to sustain the tumor growth (L), the volume fraction that tumor cells occupied within the involved breast tissue (V), and the time taken for a cell to complete mitosis(T). We have estimated L, V, and T from the literature, and then back-calcuated A for a range of diameters. We have used these four parameters as inputs and studied the time dependence of the evolution of DCIS.
 Results: We have found that the range of the values of A that we determined are within an adeqaute physiological range based on rates of proliferation and apoptosis taken from the literature. Using the model, the time to reach at least 95% of the maximum size ranges from less than 30 days for DCIS measuring 0.5 cm to almost 80 days for DCIS measuring 6 cm in diameter.
 
 Discussion: There has been little understanding of how long it takes for DCIS to grow, and whether it reaches a steady state size. Our simulations show that DCIS can grow to sizes as large as 6 cm in less than 3 months if it has the correct properties, including a high proliferation rate relative to the apoptosis rate and appropriate access to nutrients. This finding may help to explain why many cases of DCIS are not diagnosed before they progress to invasive carcinoma.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1165.

Nicotinic Acetylcholine Receptor α4 Subunit Gene Variation Associated with Chinese Han Patients with Attention Deficit Hyperactivity Disorder

Previous pharmacological, human genetical, and animal models have implicated the nicotinic acetylcholine receptor α4 subunit (CHRNA4) gene in the pathogenesis of ADHD. The objective of this study is to examine genetic association between single nucleotide polymorphisms (SNPs) in the CHRNA4 gene (rs2273502, rs1044396, rs1044397 and rs3827020 loci) and ADHD. Both case-control and family-based design were used in this study. Children aged 6 to 16 years were interviewed and assessed with the CBCL and CPRS-R to identify probands. No significant differences in frequency distribution of genotypes or alleles between the case and control groups were found. However, further haplotype analyses showed CCGG haplotype on risk for ADHD in 164 case-control sample and TDT analysis suggested that the allele C of rs2273502 over-transferred in 98 ADHD parent-offspring trios. Our findings suggest that CHRNA4 gene may play a role in the pathogenesis of ADHD, and further work is necessary to replicate and confirm what role the CHRNA4 gene may play in the etiology and pathogenesis of ADHD in large independent samples.

Cables enhances cdk2 tyrosine 15 phosphorylation by Wee1, inhibits cell growth, and is lost in many human colon and squamous cancers

Cyclin-dependent kinase 2 (cdk2) is a small serine/threonine kinase that regulates cell cycle progression. Cdk2 activity is tightly controlled by several mechanisms, including phosphorylation and dephosphorylation events. Cables is a recently described novel cdk-interacting protein. In proliferating cells, Cables was predominantly localized in the nucleus by cell fractionation and immunostaining. Expression of Cables in HeLa cells inhibited cell growth and colony formation. Cables enhanced cdk2 tyrosine 15 phosphorylation by the Wee1 protein kinase, an inhibitory phosphorylation, which led to decreased cdk2 kinase activity. The gene encoding Cables is located on human chromosome 18q11-12, a site that is frequently lost in squamous, colon, and pancreas cancers. We found that Cables was strongly expressed in normal human epithelial cells including squamous and glandular mucosa. Breast and pancreatic cancers show strong Cables expression; however, loss of Cables expression was found in approximately 50-60% of primary colon and head and neck cancer specimens. Lack of Cables expression was associated with loss of heterozygosity on chromosome 18q11. The data provide evidence for a Cables-mediated interplay between cdk2 and Wee1 that leads to inhibition of cell growth. Conversely, loss of Cables may cause uncontrolled cell growth and enhance tumor formation.

Myocyte apoptosis in the pathogenesis of ureteral damage in rats with obstructive uropathy

OBJECTIVES

To elucidate the role of signal apoptosis in the pathogenesis of ureteral damage during the course of obstructive uropathy and to investigate the cell proliferation in the smooth muscle layer of ligated ureter.

METHODS

The apoptotic cells were detected with the method of in situ end-labeling of DNA fragments. The expression of Fas, tumor necrosis factor receptor 1 (TNF-R1), and proliferation cell nuclear antigen (PCNA) was examined in 54 rats by immunohistochemistry.

RESULTS

The severity of hydroureter and the histologic changes of ureteral smooth muscle were aggravated during the period of obstruction. The apoptotic cells and the expression of Fas and PCNA in the smooth muscle layer were present since day 14 after ligation. The percentages of apoptotic cells and the expression indexes of Fas and PCNA in the smooth muscle layer progressively increased, reaching a peak on day 21 after ligation, and then declined. The expression of TNF-R1 in the smooth muscle layer was only found on day 21 after ligation. The numbers of the apoptotic cells in the smooth muscle layer correlated significantly with the expression of PCNA, Fas, and TNF-R1. The expression of Fas and TNF-R1 in the smooth muscle layer also correlated significantly. The appearance of apoptotic cells and the expression of Fas and PCNA in the smooth muscle layer were associated with tissue damage and fibrosis in the smooth muscle layer.

CONCLUSIONS

We conclude that cell apoptosis and the expression of Fas, TNF-R1, and PCNA might play important roles in the pathogenesis of ureteral damage in the smooth muscle layer of obstructed ureters.

Synaptojanin 2, a novel Rac1 effector that regulates clathrin-mediated endocytosis

The small GTPase Rac has been implicated in a wide range of cellular processes, including the organization of the actin cytoskeleton, transcriptional control and endocytic vesicle trafficking [1-3]. The signaling components that mediate these functions downstream of Rac largely remain to be identified. In this study, we have identified synaptojanin 2, a polyphosphoinositide phosphatase as a novel Rac1 effector. Synaptojanin 2 directly and specifically interacts with Rac1 in a GTP-dependent manner. Expression of constitutively active Rac1 caused the translocation of synaptojanin 2 from the cytoplasm to the plasma membrane. Both activated Rac1 and a membrane-targeted version of synaptojanin 2 inhibited endocytosis of the epidermal growth factor (EGF) and transferrin receptors, a process that is known to be dependent on polyphosphoinositide lipids. Endocytosis of growth factor receptors is thought to play an important role in the regulation of cell proliferation. Thus, these results suggest that synaptojanin 2 may mediate the inhibitory effect of Rac1 on endocytosis and could contribute to Rac1-mediated control of cell growth.

Spontaneous spinal cerebrospinal fluid leak and intracranial hypotension

A case of intracranial hypotension with spontaneous cerebrospinal fluid (CSF) leak was reported. A Tc-99m diethyltriaminepentacetic acid radionuclide cisternography (RNC) showed the accumulation of radioactivity in the area of the subarachnoid space, the poor migration of the isotope over the convexities, and the early appearance of kidney and bladder activity. To localize the site of CSF leak, RNC will be the choice, and when the time comes, RNC will work well in the location of the leak.