Large gap two-dimensional topological insulators with the coexistence of a significant Rashba effect and piezoelectricity in functionalized PbGe monolayers.

In recent years, two-dimensional (2D) multifunctional materials have become a research hotpot for their wide application range. In this work, PbGe(CN)2 and PbGe(C2H)2 are predicted to realize the piezoelectricity, quantum spin Hall (QSH) insulator, and Rashba effects simultaneously. The topological bandgaps of PbGe(CN)2 and PbGe(C2H)2 are 0.418 and 0.405 eV, respectively, which are much larger than the recently reported value of 0.165 eV for InTeO that can also attain both the piezoelectricity and QSH insulator (PQSHI) effects. The in-plane and out-of-plane piezoelectric effects coexist in both PbGe(CN)2 and PbGe(C2H)2 with the in-plane piezoelectric coefficients d11 of 8.823 and 2.913 pm V-1 and out-of-plane piezoelectric coefficients d31 of 0.638 and 0.608 pm V-1. It is worth noting that there are significant Rashba SOC effects in PbGe(CN)2 and PbGe(C2H)2 and their Rashba splitting parameters are 2.576 and 2.184 eV Å, respectively. The prominent Rashba effects, which don't exist in other PQSHI materials, make PbGe(CN)2 and PbGe(C2H)2 more suitable for application in spintronic devices. Besides, the topological properties can remain robust under the uniaxial strain within the range of -6% to 6%. Our results imply that PbGe(CN)2 and PbGe(C2H)2 qualify as potential candidates for low-power, highly sensitive piezoelectric devices, such as pressure sensors for converting mechanical energy into electrical energy.

Adsorption and photodegradation of reactive red 120 with nickel-iron-layered double hydroxide/biochar composites.

Layered double hydroxide (LDH) materials were widely applied for adsorption and photodegradation of pollutants for wastewater treatment. New efficient LDH materials with adsorption and photodegradation abilities will be promising candidates for pollutants removal. Hence, a series of NiFe-LDH/biochar (NiFe/BC) were fabricated by the coprecipitation method for synergistic adsorption and photodegradation anionic dyes of reactive red 120 (RR120). The removal experiment showed that the addition of an appropriate amount of biochar into NiFe-LDH enhanced the adsorption capacity and its photocatalytic ability. The optimized NiFe/BC2 composite can remove 88.5 % of RR120 under visible light by adsorption and photocatalysis, which was much better than NiFe-LDH (63.3 %) and biochar (2.6 %). The photodegradation kinetic constant of the NiFe/BC2 composite was 3.1 and 104.8 times that of NiFe-LDH and BC. In addition, active species capture experiments and electron spin resonance (ESR) tests revealed the removal mechanisms of NiFe/BC composites for RR120 removal. This work affords a feasible strategy for preparing LDH-based photocatalyst with excellent adsorption and photocatalytic performance for wastewater treatment.

Large Gap Two-Dimensional Topological Insulators with the Significant Rashba Effect in Ethynyl and Methyl Functionalized PbSn Monolayers.

Two-dimensional (2D) topological insulators (TIs) have recently attracted a great deal of attention due to their nondissipation electron transmission, stable performance, and easy device integration. However, a primary obstacle to influencing 2D TIs is the small bandgap, which limits their room-temperature applications. Here, we adopted first-principles to predict inversion-asymmetric group IV monolayers, PbSn(C2H)2 and PbSn(CH3)2, to be quantum spin Hall (QSH) insulators with large topological gaps of 0.586 and 0.481 eV, respectively. The nontrivial band topologies, which can survive in a wide range of strain, are characterized by topological invariants Z2, gapless edge states, and the Berry curvature. Another intriguing characteristic is the significant Rashba SOC effect which can also be tuned by feasible compressive and tensile strains. Meanwhile, the hexagonal boron nitride (h-BN) provides a suitable substrate for growth of these films without influencing their topological phases. These novel materials are expected to accelerate the development of advanced quantum devices.

Effect of metal decoration on sulfur-based gas molecules adsorption on phosphorene.

Based on first-principles calculation, the adsorption of sulfur-based gas molecules (H2S, SO2, SO3) on various metal-decorated phosphorenes is researched systematically. Eleven metals (Li, Na, K, Rb, Cs, Ca, Sr, Ba, Ni, La, Tl) which can avoid the formation of clusters on the phosphorene are considered. Noticeably, all metal decorations can enhance the adsorption strength of phosphorene to sulfur-based gas molecules except for H2S on Tl-decorated phosphorene. Meanwhile, the adsorption energy (Eads) shows the trend of Eads(H2S) < Eads(SO2) < Eads(SO3) for the same metal decoration case. In addition, some metal-decorated phosphorene systems exhibit intriguing magnetic and electrical variation after sulfur-based gas molecule adsorptions, indicating that these systems are promising to be candidates for the detection and removal of sulfur-based gas molecules.

Further improved stability criteria for uncertain T-S fuzzy systems with time-varying delay by (m,N)-delay-partitioning approach.

This paper mainly focuses on the robust stability criteria for uncertain T-S fuzzy systems with time-varying delay by (m,N)-delay-partitioning approach. A modified augmented LKF is established by partitioning the delay in all integral terms. Via taking into account of (i) the relationship between each subinterval and time-varying delay and (ii) the independent upper bounds of the delay derivative in the various delay intervals, some new results on tighter bounding inequalities such as Peng-Park׳s integral inequality and Free-Matrix-based integral inequality are introduced to effectively reduce the enlargement in bounding the derivative of LKF as much as possible, therefore, significant less conservative results can be expected in terms of es and LMIs, which can be solved efficiently with the Matlab LMI toolbox. Furthermore, it is worth mentioning that, when the delay-partitioning number m is fixed, the conservatism is gradually reduced with the increase of another delay-partitioning number N, but without increasing any computing burden. Finally, two numerical examples are included to show that the proposed method is less conservative than existing ones.

Further improved stability criteria for uncertain T-S fuzzy systems with interval time-varying delay by delay-partitioning approach.

This paper focuses on further improved stability criteria for uncertain T-S fuzzy systems with interval time-varying delay by a delay-partitioning approach. A modified augmented Lyapunov-Krasovskii functional (LKF) is established by partitioning the delay in all integral terms. Then some tighter bounding inequalities, i.e., Peng-Park׳s integral inequality (reciprocally convex approach) and the Free-Matrix-Based integral inequality (which yields less conservative stability criteria than the use of Wirtinger-based inequality does) are introduced to reduce the enlargement in bounding the derivative of LKF as much as possible, therefore, less conservative results can be expected in terms of es and LMIs. Finally, a numerical example is included to show that the proposed methods are less conservative than existing ones.

Ecdysone receptor (EcR) is involved in the transcription of cell cycle genes in the silkworm.

EcR (ecdysone receptor)-mediated ecdysone signaling pathway contributes to regulate the transcription of genes involved in various processes during insect development. In this work, we detected the expression of EcR gene in silkworm ovary-derived BmN4 cells and found that EcR RNAi result in an alteration of cell shape, indicating that EcR may orchestrate cell cycle progression. EcR RNAi and EcR overexpression analysis revealed that in the cultured BmN4 cells, EcR respectively promoted and suppressed the transcription of E2F-1 and CycE, two genes controlling cell cycle progression. Further examination demonstrated that ecdysone application in BmN4 cells not only changed the transcription of these two cell cycle genes like that under EcR overexpression, but also induced cell cycle arrest at G2/M phase. In vivo analysis confirmed that E2F-1 expression was elevated in silk gland of silkworm larvae after ecdysone application, which is same as its response to ecdysone in BmN4 cells. However, ecdysone also promotes CycE transcription in silk gland, and this is converse with the observation in BmN4 cells. These results provide new insights into understanding the roles of EcR-mediated ecdysone signaling in the regulation of cell cycle.

Screening and identification of potential predictive biomarkers for Down's syndrome from second trimester maternal serum.

OBJECTIVE: In this study, we aimed to search for noninvasive predictive biomarkers for prenatal diagnosis of Down's syndrome (DS). METHODS: Maternal serum samples from five DS-affected pregnant women and five DS-unaffected women were analyzed by 2D gel electrophoresis and MALDI-TOF mass spectrometry to screen for potential predictive biomarkers of DS. Then, differential levels of dGTPase, ß2-glycoprotein I (ß2-GPI), complement factor H-related protein 1 precursor (CFHR1) and kininogen 1 isoform 2 were further verified by western blotting tests in another independent group. RESULTS: Statistical analysis results revealed 29 protein spots whose levels differed significantly in the DS-affected pregnancies group. Of these, the eight most differentially expressed in DP were identified successfully. Among these, levels of dGTPase, CFHR1 and kininogen 1 were elevated significantly, whereas ß2-GPI was reduced in DP. DISCUSSION: These preliminarily verified proteins might serve as potential predictive biomarkers for DS-affected pregnancies.

Nuclear import of transcription factor BR-C is mediated by its interaction with RACK1.

The transcription factor Broad Complex (BR-C) is an early ecdysone response gene in insects and contains two types of domains: two zinc finger domains for the activation of gene transcription and a Bric-a-brac/Tramtrack/Broad complex (BTB) domain for protein-protein interaction. Although the mechanism of zinc finger-mediated gene transcription is well studied, the partners interacting with the BTB domain of BR-C has not been elucidated until now. Here, we performed a yeast two-hybrid screen using the BTB domain of silkworm BR-C as bait and identified the receptor for activated C-kinase 1 (RACK1), a scaffolding/anchoring protein, as the novel partner capable of interacting with BR-C. The interaction between BR-C and RACK1 was further confirmed by far-western blotting and pull-down assays. Importantly, the disruption of this interaction, via RNAi against the endogenous RACK1 gene or deletion of the BTB domain, abolished the nuclear import of BR-C in BmN4 cells. In addition, RNAi against the endogenous PKC gene as well as phosphorylation-deficient mutation of the predicted PKC phosphorylation sites at either Ser373 or Thr406 in BR-C phenocopied RACK1 RNAi and altered the nuclear localization of BR-C. However, when BTB domain was deleted, phosphorylation mimics of either Ser373 or Thr406 had no effect on the nuclear import of BR-C. Moreover, mutating the PKC phosphorylation sites at Ser373 and Thr406 or deleting the BTB domain significantly decreased the transcriptional activation of a BR-C target gene. Given that RACK1 is necessary for recruiting PKC to close and phosphorylate target proteins, we suggest that the PKC-mediated phosphorylation and nuclear import of BR-C is determined by its interaction with RACK1. This novel finding will be helpful for further deciphering the mechanism underlying the role of BR-C proteins during insect development.

Identification and Expression Profiling of the BTB Domain-Containing Protein Gene Family in the Silkworm, Bombyx mori.

The BTB domain is a conserved protein-protein interaction motif. In this study, we identified 56 BTB domain-containing protein genes in the silkworm, in addition to 46 in the honey bee, 55 in the red flour beetle, and 53 in the monarch butterfly. Silkworm BTB protein genes were classified into nine subfamilies according to their domain architecture, and most of them could be mapped on the different chromosomes. Phylogenetic analysis suggests that silkworm BTB protein genes may have undergone a duplication event in three subfamilies: BTB-BACK-Kelch, BTB-BACK-PHR, and BTB-FLYWCH. Comparative analysis demonstrated that the orthologs of each of 13 BTB protein genes present a rigorous orthologous relationship in the silkworm and other surveyed insects, indicating conserved functions of these genes during insect evolution. Furthermore, several silkworm BTB protein genes exhibited sex-specific expression in larval tissues or at different stages during metamorphosis. These findings not only contribute to a better understanding of the evolution of insect BTB protein gene families but also provide a basis for further investigation of the functions of BTB protein genes in the silkworm.

RNAi silencing of the SoxE gene suppresses cell proliferation in silkworm BmN4 cells.

The transcription factor SoxE is mainly expressed in the gonad and involved in the regulation of gonad development and sex determination in animals. Here, we used the silkworm ovary-derived BmN4-SID1 cell line to survey the roles of the silkworm SoxE protein (BmSoxE) and predict its candidate binding targets. RNAi-mediated silencing of BmSoxE expression suppressed cell proliferation in BmN4-SID1 cells. A further cell cycle analysis revealed that this inhibition of cell proliferation was largely due to cell cycle arrest in G1 phase when BmSoxE expression was blocked in BmN4-SID1 cells. Genome-wide microarray expression analyses demonstrated that the expression levels of a set of genes were significantly altered following BmSoxE RNAi. More than half of these genes contained conserved binding sites for HMG box domain of the Sox proteins and were predicted to be candidate binding targets for BmSoxE. Importantly, some of the candidate targets may be associated with the effect of BmSoxE on cell proliferation. Several candidate target genes showed gonad-specific expression in silkworm larvae. Taken together, these data demonstrate that BmSoxE is required for cell proliferation in silkworm BmN4-SID1 cells and provide valuable information for further investigations of the molecular control exerted by the BmSoxE protein over cell proliferation and gonad development in the silkworm.

[Effect of lat disruption on clavulanic acid production].

A 1.8kb fragment of lat was obtained from Streptomyces clavuligerus 27064, and replacement plasmid of pXAL1 and pXAL2 were constructed. PXAL1 and pXAL2 were used to disrupt the lat gene by bi-parental conjugation from E. coli to Streptomyces clavuligerus. A Am(r)Thio(S) transformant, named as XAL863, was obtained. The genome of Streptomyces clavuligerus 27064 and XAL863 was analyzed by southern blot technique, and the activity of lysine epsilon-aminotransferase in the two strains was also tested. Both results proved that the lat was disrupted in the XAL863. Streptomyces clavuligerus and XAL863 were cultured in the shaken flask respectively, and the production of clavulanic acid was analyzed by HPLC with the different incubation time interval, and the yield was approximately 1.8 times higher in the XAL863 at their highest production point.