Electron self-energy and effective mass in a single heterostructure

In this paper, we investigate the electron self-energy and effective mass in a single heterostructure using Green-function method. Numerical calculations of the electron self-energy and effective mass for GaAs/AlAs heterostructure are performed. The results show that the self energy (effective mass) of electron, which incorporate the energy of electron coupling to interface-optical phonons and half three-dimension LO phonons, monotonically increase(decrease) from that of interface polaron to that of 3D bulk polaron with the increase of the distance between the position of the electron and interface.Comment: 10 pages, 2 figure

Modification of slope stability probability classification and its application to rock slopes in hydropower engineering regions

Stability assessment of rock slopes in hydropower engineering regions is an important and complex issue. Rock mass classification systems are a good approach because they thoroughly consider many factors influencing rock slope stability. The slope stability probability classification (SSPC) system is a novel method. However, it has two obvious limitations when applied to rock slopes: 1) it is only suitable for slopes less than 45 m in height, and 2) there is great subjectivity and randomness in the estimation of intact rock strength. Therefore, this study presents two modifications of the SSPC system by adopting the Hoek–Brown strength criterion and an empirical formula for maximum slope height. Evaluation of results from of 34 typical rock slopes of the major hydropower engineering regions in China indicated that the accuracy rate of the modified SSPC for stability evaluation of these slopes was 61.8%, and the accuracy for stability evaluation of 10 slopes with non-structural control failure was 80%. The stability values of stable and unstable slopes obtained using the modified SSPC were different to those obtained using the Chinese Slope Mass Rating (CSMR) and modified CSMR systems. In addition, the identification accuracy rate of the modified SSPC was significantly higher than that of the CSMR and modified CSMR. Therefore, the modified SSPC can be applied to hydropower engineering regions, providing a new means of rapidly evaluating the slope stability of high rock slopes (slopes > 45 m in height) in these regions.</p

Clinical efficacy of Conbercept combined with vitrectomy for proliferative vitreoretinopathy after choroidal detachment

AIM: To evaluate the clinical effect of Conbercept combined with vitrectomy in the treatment of proliferative vitreoretinopathy(PVR)after choroidal detachment. METHODS: From January 2015 to January 2018, 66 eyes of 64 patients with PVR were treated in our hospital. All the patients were randomly divided into control group(32 cases, 34 eyes)and observation group(32 cases, 32 eyes). The control group was treated with routine vitreoretinal surgery. The observation group was treated with routine vitreoretinal surgery combined with intravitreal injection of conbercept. The clinical efficacy, operative duration, intraoperative bleeding, incidence of iatrogenic holes and the best corrected visual acuity(BCVA), subfoveal choroidal thickness before and after treatment were compared between the two groups. RESULTS: After 3-6mo follow-up, the total effective rate in the observation group(94%)was significantly higher than that in the control group(74%), and the difference was statistically significant(PPP>0.05). After treatment, the above indexes were lower than those before treatment. The levels of serum VEGF and bFGF in the observation group were significantly lower than those in the control group(PP>0.05). The BCVA of the two groups was significantly higher than that before treatment. The thickness of subfoveal choroid in the observation group was significantly lower than that before surgery(PPCONCLUSION: Vitrectomy combined with intravitreal injection of conbercept in the treatment of PVR after choroidal detachment has a good effect. It can effectively shorten the operation time, reduce the incidence of intraoperative hemorrhage and iatrogenic hole, and reduce the level of serum VEGF and bFGF content. Improve the visual acuity and reduce the thickness of choroid

Bis[4-hy­droxy-3,5-dimeth­oxy­benzalde­hyde (2,4-dinitro­phen­yl)hydrazone] N,N-dimethyl­formamide disolvate monohydrate

In the title compound, 2C15H14N4O7·2C3H7NO·H2O, the hydrazone mol­ecules are roughly planar, with the two benzene rings twisted slightly relative to each other by dihedral angle of 6.04 (11) and 7.75 (11)° in the two mol­ecules. The water mol­ecule is linked to the Schiff base mol­ecule by an O—H⋯O hydrogen bond. Intra­molecular N—H⋯O hydrogen bonds occur. In the crystal, mol­ecules are linked by inter­molecular N—H⋯O and O—H⋯O hydrogen bonds

Fairy circles reveal the resilience of self-organized salt marshes

Spatial patterning is a fascinating theme in both theoretical and experimental ecology. It reveals resilience and stability to withstand external disturbances and environmental stresses. However, existing studies mainly focus on well-developed persistent patterns rather than transient patterns in self-organizing ecosystems. Here, combining models and experimental evidence, we show that transient fairy circle patterns in intertidal salt marshes can both infer the underlying ecological mechanisms and provide a measure of resilience. The models based on sulfide accumulation and nutrient depletion mechanisms reproduced the field-observed fairy circles, providing a generalized perspective on the emergence of transient patterns in salt marsh ecosystems. Field experiments showed that nitrogen fertilization mitigates depletion stress and shifts plant growth from negative to positive in the center of patches. Hence, nutrient depletion plays an overriding role, as only this process can explain the concentric rings. Our findings imply that the emergence of transient patterns can identify the ecological processes underlying pattern formation and the factors determining the ecological resilience of salt marsh ecosystems

Occurrence and Biodegradation of Nonylphenol in the Environment

Nonylphenol (NP) is an ultimate degradation product of nonylphenol polyethoxylates (NPE) that is primarily used in cleaning and industrial processes. Its widespread use has led to the wide existence of NP in various environmental matrices, such as water, sediment, air and soil. NP can be decreased by biodegradation through the action of microorganisms under aerobic or anaerobic conditions. Half-lives of biodegradation ranged from a few days to almost one hundred days. The degradation rate for NP was influenced by temperature, pH and additions of yeast extracts, surfactants, aluminum sulfate, acetate, pyruvate, lactate, manganese dioxide, ferric chloride, sodium chloride, hydrogen peroxide, heavy metals, and phthalic acid esters. Although NP is present at low concentrations in the environment, as an endocrine disruptor the risks of long-term exposure to low concentrations remain largely unknown. This paper reviews the occurrence of NP in the environment and its aerobic and anaerobic biodegradation in natural environments and sewage treatment plants, which is essential for assessing the potential risk associated with low level exposure to NP and other endocrine disruptors

Nuclear factor κB controls acetylcholine receptor clustering at the neuromuscular junction

At the vertebrate neuromuscular junction (NMJ), acetylcholine receptor (AChR) clustering is stimulated by motor neuron-derived glycoprotein Agrin and requires a number of intracellular signal or structural proteins, including AChR-associated scaffold protein Rapsyn. Here, we report a role of nuclear factor κB (NF-κB), a well known transcription factor involved in a variety of immune responses, in regulating AChR clustering at the NMJ. We found that downregulating the expression of RelA/p65 subunit of NF-κB or inhibiting NF-κB activity by overexpression of mutated form of IκB (inhibitor κB), which is resistant to proteolytic degradation and thus constitutively keeps NF-κB inactive in the cytoplasma, impeded the formation of AChR clusters in cultured C2C12 muscle cells stimulated by Agrin. In contrast, overexpression of RelA/p65 promoted AChR clustering. Furthermore, we investigated the mechanism by which NF-κB regulates AChR clustering. Interestingly, we found that downregulating the expression of RelA/p65 caused a marked reduction in the protein and mRNA level of Rapsyn and upregulation of RelA/p65 enhanced Rapsyn promoter activity. Mutation of NF-κB binding site on Rapsyn promoter prevented responsiveness to RelA/p65 regulation. Moreover, forced expression of Rapsyn in RelA/p65 downregulated muscle cells partially rescued AChR clusters, suggesting that NF-κB regulates AChR clustering, at least partially through the transcriptional regulation of Rapsyn. In line with this notion, genetic ablation of RelA/p65 selectively in the skeletal muscle caused a reduction of AChR density at the NMJ and a decrease in the level of Rapsyn. Thus, NF-κB signaling controls AChR clustering through transcriptional regulation of synaptic protein Rapsyn. Copyrigh

Poly[diaqua-1κ2 O-bis[μ3-2-(1H-tetra­zol-5-yl)benzoato(2−)]dicadmium(II)]

The title compound, [Cd2(C8H4N4O2)2(H2O)2]n, is a coordination polymer prepared by the hydro­thermal reaction of cadmium(II) chloride and 2-(1H-tetra­zol-5-yl)benzoic acid. Two types of coordinated cadmium cations exist in the structure. One is located on a twofold axis and is coordinated by four O and two N atoms from four symmetry-related ligands, forming a trigonal-prismatic coordination polyhedron. The other is located on an inversion center and is octa­hedrally coordinated by two N and two O atoms from two ligands in equatorial sites, and two water mol­ecules in axial sites. The organic ligand bridges three Cd atoms, through a carboxyl­ate group and two N atoms of the tetra­zolate unit. This mode of coordination results in a two-dimensional framework. The crystal structure is stabilized by inter­molecular O—H⋯O and O—H⋯N hydrogen bonds