Vertical organic electrochemical transistors for complementary circuits.

Organic electrochemical transistors (OECTs) and OECT-based circuitry offer great potential in bioelectronics, wearable electronics and artificial neuromorphic electronics because of their exceptionally low driving voltages (<1 V), low power consumption (<1 µW), high transconductances (>10 mS) and biocompatibility1-5. However, the successful realization of critical complementary logic OECTs is currently limited by temporal and/or operational instability, slow redox processes and/or switching, incompatibility with high-density monolithic integration and inferior n-type OECT performance6-8. Here we demonstrate p- and n-type vertical OECTs with balanced and ultra-high performance by blending redox-active semiconducting polymers with a redox-inactive photocurable and/or photopatternable polymer to form an ion-permeable semiconducting channel, implemented in a simple, scalable vertical architecture that has a dense, impermeable top contact. Footprint current densities exceeding 1 kA cm-2 at less than ±0.7 V, transconductances of 0.2-0.4 S, short transient times of less than 1 ms and ultra-stable switching (>50,000 cycles) are achieved in, to our knowledge, the first vertically stacked complementary vertical OECT logic circuits. This architecture opens many possibilities for fundamental studies of organic semiconductor redox chemistry and physics in nanoscopically confined spaces, without macroscopic electrolyte contact, as well as wearable and implantable device applications.

A confinement-regulated (H3C-NH3)+ ion as a smallest dual-wheel rotator showing bisected rotation dynamics.

On the basis of variable-temperature single-crystal X-ray diffraction, rotational energy barrier analysis, variable-temperature/frequency dielectric response, and molecular dynamics simulations, here we report a new crystalline supramolecular rotor (CH3NH3)(18-crown-6)[CuCl3], in which the (H3C-NH3)+ ion functions as a smallest dual-wheel rotator showing bisected rotation dynamics, while the host 18-crown-6 macrocycle behaves as a stator that is not strictly stationary. This study also provides a helpful insight into the dynamics of ubiquitous -CH3/-NH3 groups confined in organic or organic-inorganic hybrid solids.

In Situ Vaccination with An Injectable Nucleic Acid Hydrogel for Synergistic Cancer Immunotherapy.

Recently, therapeutic cancer vaccines have emerged as promising candidates for cancer immunotherapy. Nevertheless, their efficacies are frequently impeded by challenges including inadequate antigen encapsulation, insufficient immune activation, and immunosuppressive tumor microenvironment. Herein, we report a three-in-one hydrogel assembled by nucleic acids (NAs) that can serve as a vaccine to in situ trigger strong immune response against cancer. Through site-specifically grafting the chemodrug, 7-ethyl-10-hydroxycamptothecin (also known as SN38), onto three component phosphorothioate (PS) DNA strands, a Y-shaped motif (Y-motif) with sticky ends is self-assembled, at one terminus of which an unmethylated cytosine-phosphate-guanine (CpG) segment is introduced as an immune agonist. Thereafter, programmed cell death ligand-1 (PD-L1) siRNA that performs as immune checkpoint inhibitor is designed as a crosslinker to assemble with the CpG- and SN38-containing Y-motif, resulting in the formation of final NA hydrogel vaccine. With three functional agents inside, the hydrogel can remarkably induce the immunogenic cell death to enhance the antigen presentation, promoting the dendritic cell maturation and effector T lymphocyte infiltration, as well as relieving the immunosuppressive tumor environment. When inoculated twice at tumor sites, the vaccine demonstrates a substantial antitumor effect in melanoma mouse model, proving its potential as a general platform for synergistic cancer immunotherapy.

Precisely Patterned Channels in a Vertical Organic Electrochemical Transistor with a Diazirine Photo-Crosslinker.

Organic electrochemical transistors (OECTs) rely on both efficient ionic doping/de-doping process and carrier transport in the mixed ionic-electronic channel under the modulation of gate bias. Moreover, channels that hold photopatterning capability are highly desired to minimize parasitic capacitance and simplify the fabrication process/cost. However, yielding photo-patternable channels with both precise/robust patterning capability and controllable ionic-electronic coupling is still challenging. Herein, double-end trifluoromethyl diazirines (DtFDA) with different chain lengths are introduced in the OECT channel to act as both photo-crosslinker and medium to regulate ionic-electronic transport. Specifically, high-resolution patterns with a minimum line width/gap of 2 µm are realized in p(g2T-T) or Homo-gDPP based channels by introducing DtFDA. Maximum transconductances of 68.6 mS and 81.6 mS, current on/off ratio of 106 and 107 (under a drain voltage of only ±0.1 V), are achieved in p- and n-type vertical OECTs (vOECTs), respectively, along with current densities exceeding 1 kA cm-2 and good cycling stability of more than 100,000 cycles (2000 seconds). This work provides a new and facile strategy for the fabrication of vOECT channels with high resolution and high performance via the introduction of a simple and efficient crosslinker.

Pure Silica with Ordered Silanols for Propylene/Propane Adsorptive Separation Unraveled by Three-Dimensional Electron Diffraction.

Adsorptive separation of propylene (C3H6) from propane (C3H8), which could deal with energy-intensive cryogenic distillation technologies, remains challenging due to their similar physiochemical properties. Herein, we present a pure silica zeolite with ordered silanols (OSs), whose crystallographic structure was unraveled by the advanced three-dimensional electron diffraction (3D ED), displaying the highly efficient separation of propylene from propane under ambient conditions. The 3D ED technique enables us to investigate its 8-ring pore opening transformation from the round one to the elliptical one during the removal of organic structure-directing agents. Such unique elliptical 8-ring pore openings can exclude larger-size propane and only adsorb propylene. Its C3H6/C3H8 separation performance is also confirmed by column breakthrough experiments, showing a high dynamic adsorption capacity of 53.36 cm3 g-1 for C3H6 but negligible C3H8 under ambient conditions. The dynamic capacity for C3H6 is superior to that of the well-known pure silica DDR-type zeolite (31.07 cm3 g-1). The density functional theory calculation demonstrates that the adsorbed propylene is distributed in the heart-shaped cavity and has a weak interaction with the OSs.

Novel miR-108 and miR-234 target juvenile hormone esterase to regulate the response of Plutella xylostella to Cry1Ac protoxin.

Insect hormones, such as juvenile hormone (JH), precisely regulate insect life-history traits. The regulation of JH is tightly associated with the tolerance or resistance to Bacillus thuringiensis (Bt). JH esterase (JHE) is a primary JH-specific metabolic enzyme which plays a key role in regulating JH titer. Here, we characterized a JHE gene from Plutella xylostella (PxJHE), and found it was differentially expressed in the Bt Cry1Ac resistant and susceptible strains. Suppression of PxJHE expression with RNAi increased the tolerance of P. xylostella to Cry1Ac protoxin. To investigate the regulatory mechanism of PxJHE, two target site prediction algorithms were applied to predict the putative miRNAs targeting PxJHE, and the resulting putative miRNAs were subsequently verified for their function targeting PxJHE using luciferase reporter assay and RNA immunoprecipitation. MiR-108 or miR-234 agomir delivery dramatically reduced PxJHE expression in vivo, whilst only miR-108 overexpression consequently increased the tolerance of P. xylostella larvae to Cry1Ac protoxin. By contrast, reduction of miR-108 or miR-234 dramatically increased PxJHE expression, accompanied by the decreased tolerance to Cry1Ac protoxin. Furthermore, injection of miR-108 or miR-234 led to developmental defects in P. xylostella, whilst injection of antagomir did not cause any obvious abnormal phenotypes. Our results indicated that miR-108 or miR-234 can be applied as potential molecular targets to combat P. xylostella and perhaps other lepidopteran pests, providing novel insights into miRNA-based integrated pest management.

DNA Zipper Mediated Membrane Fusion for Rapid Exosomal MiRNA Detection.

Accurate and reliable detection of exosomal miRNA can serve as a promising method for early diagnosis of disease and evaluation of therapeutic effects. However, current exosomal miRNA detection methods commonly involve exosome enrichment, containing RNA extraction, and qRT-PCR based quantification, which are expensive and time-consuming. Herein, we develop a DNA zipper-mediated membrane fusion approach for rapid exosomal miRNA detection and cancer diagnosis. First, a lipid vesicle probe containing miR21-targeting molecular beacons (MBs) is constructed and further loaded with zipper DNA constructs (ZDCs) on its surface. Meanwhile, complementary zipper DNA constructs (cZDCs) are introduced on the exosome of interest. Upon mixing them together, zipping between ZDC and cZDC induces the membrane fusion of exosomes and vesicle probes, triggering the recognition of exosomal miR21 by contained MBs and fluorescence emission that can be conveniently detected within 30 min. Importantly, with the assistance of flow cytometry, miR21-overexpressed tumor exosomes derived from either cell culture medium or clinical patient serums can be distinguished from exosomes secreted from normal cells. This approach provides a convenient way to accurately detect the exosomal miRNA, which may hold great potential in liquid biopsy for early cancer diagnosis and monitoring the therapeutic effects during the treatments.

Flexible yet Robust Framework of Tin(II) Oxide Carbodiimide for Reversible Lithium Storage.

Metal-organic frameworks (MOFs) can become promising electrode materials for advanced lithium-ion batteries (LIBs), because their loosely packed porous structures may mitigate volume expansion and metal atom aggregation, which occur at the respective metal oxides. However, they suffer from poor electrical conductivity and irreversible structural degradation upon charge/discharge processes, which impede their practical utilization. Herein, we investigate MOF-like Sn2 O(CN2 ) as a new electrode material. The conductive yet flexible [N=C=N] linkers are tilted between [Sn4 O] nodes and cross-linked into a porous quasi-layered structure. Such structure offers abundant channels for fast Li-ion transport and tolerance of enormous volume expansion. Notably, anisotropic [N=C=N]2- arrays hardly migrate so that Sn0 nanodots are physically separated via robust [N=C=N]2- framework during discharge, thereby effectively preventing the formation of large Sn islands. Owing to the structural advantage, the Sn2 O(CN2 ) electrode exhibits an initial Coulombic efficiency as high as ∼80 %. With the addition of graphite as conductive supporter, the electrode provides 978 mAh g-1 at 1.0 A g-1 even after 300 cycles. Such MOF-like carbodiimides hold potential for the advanced electrodes in LIBs and other battery systems.

Circ_0029803 serves as the sponge of miR-216b-5p to promote the progression of colorectal cancer by regulating SKIL expression.

BACKGROUND: Circular RNA 0029803 (circ_0029803) was found to be upregulated in colorectal cancer (CRC) tissues, but its function and underlying molecular mechanism are not studied in CRC. METHODS: The expression levels of circ_0029803, microRNA-216b-5p (miR-216b-5p), and ski-oncogene-like (SKIL) were measured by quantitative real-time polymerase chain reaction (qRT-PCR). RNase R treatment was used to affirm the existence of circ_0029803. Cell proliferation, apoptosis, migration, and invasion were assessed by colony formation, flow cytometry, and Transwell assays, respectively. A glucose and lactate assay kit was used to detect glucose consumption and lactate production. Western blot was applied to analyze the levels of all proteins. Dual-luciferase reporter assay was performed to assess the relationship between miR-216b-5p and circ_0029803 or SKIL. Tumor xenograft models were established to elucidate the effect of circ_0029803 in vivo. RESULTS: Circ_0029803 expression was enhanced in CRC tissues and cells, and the 5-year overall survival rate of patients with high circ_0029803 expression was substantially reduced. Circ_0029803 depletion retarded proliferation, migration, invasion, EMT and glycolysis of CRC cells in vitro as well as the tumor growth in vivo. Mechanically, circ_0029803 could serve as miR-216b-5p sponge to regulate its expression, and miR-216b-5p knockdown reversed the inhibition of si-circ_0029803 on the malignant behaviors of CRC cells. Additionally, as the target mRNA of miR-216b-5p, SKIL could counteract the inhibitory effect of miR-216b-5p on the development of CRC cells. Importantly, silencing circ_0029803 reduced SKIL expression via sponging miR-216b-5p. CONCLUSION: Circ_0029803 knockdown hindered proliferation, migration, invasion, EMT, and glycolysis and promoted apoptosis in CRC cells by modulating the miR-216b-5p/SKIL axis.

Bismuth Oxyhydroxide-Pt Inverse Interface for Enhanced Methanol Electrooxidation Performance.

Developing efficient Pt-based electrocatalysts for the methanol oxidation reaction (MOR) is of pivotal importance for large-scale application of direct methanol fuel cells (DMFCs), but Pt suffers from severe deactivation brought by the carbonaceous intermediates such as CO. Here, we demonstrate the formation of a bismuth oxyhydroxide (BiOx(OH)y)-Pt inverse interface via electrochemical reconstruction for enhanced methanol oxidation. By combining density functional theory calculations, X-ray absorption spectroscopy, ambient pressure X-ray photoelectron spectroscopy, and electrochemical characterizations, we reveal that the BiOx(OH)y-Pt inverse interface can induce the electron deficiency of neighboring Pt; this would result in weakened CO adsorption and strengthened OH adsorption, thereby facilitating the removal of the poisonous intermediates and ensuring the high activity and good stability of Pt2Bi sample. This work provides a comprehensive understanding of the inverse interface structure and deep insight into the active sites for MOR, offering great opportunities for rational fabrication of efficient electrocatalysts for DMFCs.

ß-Asarone Exerts Antioxidative Effects on H2O2-Stimulated PC12 Cells by Activating Nrf2/HO-1 Pathway.

Oxidative stress-mediated neuron damage is considered an important contributor to the pathogenesis and development of neurodegenerative diseases. Although ß-asarone is widely known for its neuroprotective pharmacological properties, the exact mechanism of ß-asarone against oxidative stress has not been fully elucidated. The aim of the present study was to investigate underlying mechanisms of ß-asarone against oxidative damage in PC12 cells. Our results demonstrated that the treatment of ß-asarone significantly alleviated the reduction in cell viability and the excessive accumulation of lactate dehydrogenase (LDH), malondialdehyde (MDA) and reactive oxygen species (ROS) by increasing the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH). Moreover, ß-asarone pretreatment also activated nuclear factor 2 erythroid-related factor 2 (Nrf2) and its downstream target heme oxygenase-1 (HO-1), which was involved in quenching reactive oxygen to inhibit oxidative stress. Furthermore, when silenced by Nrf2 siRNA, the protective effect of ß-asarone was reduced and the oxidative stress induced by H2O2 was enhanced. In conclusion, our findings revealed that ß-asarone could reduce oxidative stress via activating Nrf2/HO-1 pathway in PC12 cells, highlighting the potential therapeutic role of ß-asarone in neurodegenerative diseases.

Functional characterization of T3SS C-ring component VscQ and evaluation of its mutant as a live attenuated vaccine in zebrafish (Danio rerio) model.

Vibrio alginolyticus, a Gram-negative bacterium, has been recognized as an opportunistic pathogen in marine animals as well as humans. Type III secretion system (T3SS) is critical for pathogen virulence and disease development. However, no more information is known about the C-ring component VscQ and its physiological role. In this study, gene vscQ was cloned from V. alginolyticus wild-type strain HY9901 and the mutant strain HY9901ΔvscQ was constructed by the in-frame deletion method. The HY9901ΔvscQ mutant showed an attenuated swarming phenotype and a closely 4.6-fold decrease in the virulence to Danio rerio. However, the HY9901ΔvscQ mutant showed no difference in growth, biofilm formation and ECPase activity. HY9901ΔvscQ reduces the release of LDH, NO and caspase-3 activity of infected FHM cell, which are involved in fish cell apoptosis. Deletion of gene vscQ downregulates the expression level of T3SS-related genes including vscL, vopB, hop, vscO, vscK, vopD, vcrV and vopS and flagellum-related genes (flaA and fliG). And Danio rerio vaccinated via i.m injection with HY9901ΔvscQ induced a relative percent survival (RPS) value of 71% after challenging with the wild-type HY9901. Real-time PCR assays showed that vaccination with HY9901ΔvscQ enhanced the expression of immune-related genes, including TNF-α, TLR5, IL-6R, IgM and c/ebpß in liver and spleen after vaccination, indicating that it is able to induce humoral and cell-mediated immune response in zebrafish. These results demonstrate that the HY9901ΔvscQ mutant could be used as an effective live vaccine to combat V. alginolyticus infection.

Novel inorganic aromatic mixed-valent superalkali electride CaN3Ca: an alkaline-earth-based high-sensitivity multi-state nonlinear optical molecular switch.

Focusing on innovative high-performance single-pole double-throw nonlinear optical (NLO) molecular switches, two C3v configurations (1 and 3) and one D3h configuration (2) of bipyramidal CaN3Ca have been obtained by using quantum mechanical methods. Not only are 1, 2, and 3 alkaline-earth-based aromatic superalkalis, but they are also interesting electrides. The salt-like electronic structures of e-Ca2+N33-Ca2+ (1) and Ca2+N33-Ca2+e- (3) with localized redox centres are rare inorganic Robin-Day class II-type structures, and e0.5-Ca2+N33-Ca2+e0.5- (2) with a delocalized structure is a class III-type mixed-valent superalkali electride. Under a small external electric field of ±0.0110 a.u. (0.565 V Å-1), the short-distance hopping of Ca atoms in CaN3Ca from the D3h configuration with in-plane aromaticity to each C3v configuration with out-of-plane aromaticity brings about the long-range transfer of half an electron from one Ca atom to another. And, subsequently, a large dipole moment (µ0) and remarkable static first hyperpolarizability (ß0) occur. µz and ßzzz range from 0 (D3h, off form) to -12.1 or 12.1 D (C3v, on forms) and from 0 (D3h, off form) to -19 428 or 19 428 a.u. (C3v, on forms), respectively. These extremely large differences in µz and ßzzz values between the D3h and each of the C3v configurations confirm the potential of these inorganic aromatic Robin-Day-type superalkali electrides for applications in high-sensitivity multi-state nonlinear optical switches.

Suppression of microRNA-141 suppressed p53 to protect against neural apoptosis in epilepsy by SIRT1 expression.

We investigated that microRNA (miRNA)-141 protects against epilepsy-induced apoptosis and its reaction mechanism. The serum expression of miRNA-141 in epilepsy model mice and control volunteer was measured by quantitative reverse-transcription polymerase chain reaction. We found that miRNA-141 serum expression was upregulated in patients with epilepsy. Overexpression of miRNA-141 induced nerve cell apoptosis, suppressed proliferation, promoted caspase-3/9, Bax and p53 protein expression, and reduced silent information regulator 1 (SIRT1) protein expression in vitro model. In addition, the downexpression miRNA-141 using si-miRNA-141 reduced nerve cell apoptosis and increased proliferation, suppressed caspase-3/9, Bax and p53 protein expression, induced SIRT1 protein expression. SIRT1 inhibitor (nicotinamide) decreased SIRT1, reduced the effects of miRNA-141 on nerve cell apoptosis in vitro model of epilepsy through SIRT1/p53. SIRT1 agonist also reduced the effects of miRNA-141 overexpression on nerve cell apoptosis in vitro model of epilepsy through SIRT1/p53. Our preliminary findings indicate that anti-miRNA-141 protects against epilepsy-induced apoptosis via SIRT1/p53 expression.

Effects of ß-Cyclodextrin and Hydroxypropyl-ß-Cyclodextrin Inclusions on the Degradation of Magnolol by Intestinal Bacteria.

Cyclodextrin (CD) inclusions are generally used to increase the solubility of poorly soluble drugs. In this study, magnolol (MAG) was used as a model drug for exploring the effects of CD on the degradation of pharmaceutical drugs by intestinal microflora. MAG/ß-cyclodextrin (ß-CD) and MAG/hydroxypropyl-ß-CD (HP-ß-CD) inclusion complexes were successfully prepared by the saturated aqueous solution and freeze-drying methods, respectively. Structural characterisation along with analyses of solubility, residual water content and drug content of the inclusion complexes was performed. The intestinal microflora of male rats was used to study MAG degradation in vitro. At three concentrations, the degradation of both the inclusion complexes was slower than that of the MAG monomer, MAG and CD mixtures and the MAG-poloxamer 188 micelle. There were no statistically significant differences in the degradation of the MAG/ß-CD and MAG/HP-ß-CD inclusion complexes. A simulation first-order equation of the degradation parameters revealed that the degradation of the inclusion complexes was slower and pronounced, judging by slope. The experimental findings were verified by molecular docking for predicting the stable molecular structure of the inclusion complexes. In conclusion, the inclusion complexes partially protected MAG from degradation by the intestinal bacteria.

Selecting and validating reference genes for quantitative real-time PCR in Plutella xylostella (L.).

Gene expression analysis provides important clues regarding gene functions, and quantitative real-time PCR (qRT-PCR) is a widely used method in gene expression studies. Reference genes are essential for normalizing and accurately assessing gene expression. In the present study, 16 candidate reference genes (ACTB, CyPA, EF1-α, GAPDH, HSP90, NDPk, RPL13a, RPL18, RPL19, RPL32, RPL4, RPL8, RPS13, RPS4, α-TUB, and ß-TUB) from Plutella xylostella were selected to evaluate gene expression stability across different experimental conditions using five statistical algorithms (geNorm, NormFinder, Delta Ct, BestKeeper, and RefFinder). The results suggest that different reference genes or combinations of reference genes are suitable for normalization in gene expression studies of P. xylostella according to the different developmental stages, strains, tissues, and insecticide treatments. Based on the given experimental sets, the most stable reference genes were RPS4 across different developmental stages, RPL8 across different strains and tissues, and EF1-α across different insecticide treatments. A comprehensive and systematic assessment of potential reference genes for gene expression normalization is essential for post-genomic functional research in P. xylostella, a notorious pest with worldwide distribution and a high capacity to adapt and develop resistance to insecticides.

Theoretical investigations on the unsymmetrical effect of ß-link Zn-porphyrin sensitizers on the performance for dye-sensitized solar cells.

Dye sensitizers play an important role in dye-sensitized solar cells (DSSCs). As a promising strategy for the design of novel porphyrin sensitizers, the asymmetric modification of the porphyrin ring to meso-link porphyrin sensitizer has emerged in recent years, which can improve the light-harvesting properties and enhance the electron distribution. In this work, in order to reveal the essence of the effect of unsymmetrical substitution on the performance of ß-link porphyrin dyes in DSSCs, four kinds of common ß-link porphyrin dyes with different structures are calculated by using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The electronic structures and optical properties of these studied dyes in dimethylformamide (DMF) are also investigated. The key parameters of the short-circuit current density (Jsc), including light harvesting efficiency (LHE), electron injection driving force (ΔGinject), and intra-molecular charge transfer (ICT) are discussed in detail. In addition, the periodic DFT calculations in the dye-TiO2 systems are also employed to investigate the geometrical and electronic injection process of the different connection types of these studied dyes adsorbed on the periodic TiO2 model with an exposed anatase (101) surface. We expect the present study would deepen the understanding of the alternative function of unsymmetrical substitution and may contribute to future DSSC design.

Cognitive enhancing and antioxidant effects of tetrahydroxystilbene glucoside in Aß1-42-induced neurodegeneration in mice.

Polyhydroxy stilbenes have been reported to possess various biological activities, and have potential in the treatment of Alzheimer's disease (AD). Tetrahydroxystilbene glucoside is one of the major polyhydroxy stilbenes, which provides underlying therapeutic activities for neuroprotective actions in various experimental conditions. This study intends to investigate the impact of tetrahydroxystilbene glucoside remedy for cognitive disorder and oxidative stress in Aß1-42-induced AD mice and to clarify the mechanisms of action through Keap1/Nrf2 pathway. It was found that The swimming time of Aß1-42-induced mice which were treated by tetrahydroxystilbene glucoside (30, 60 and 120 mg/kg) was significantly increased in the target quadrant through the Morris water maze experiment and the number of avoidances was increased through the passive avoidance experiment. Moreover, tetrahydroxystilbene glucoside attenuated Aß1-42-induced memory impairment, however, the locomotor and exploratory activity of the mice were not affected. Tetrahydroxystilbene glucoside obviously decreased the levels of MDA and GSSG in both hippocampus and cortex compared with the Aß1-42-treated group, and obviously increased the level of GSH and activities of CAT and SOD in above tissues. The results of this study also demonstrated that tetrahydroxystilbene glucoside increased Nrf2 and HO-1 protein expression and decreased Keap1 protein expression in a concentration-dependent manner in Aß1-42-treated mice, which involved in the Keap1/Nrf2 antioxidant pathway in hippocampus and cerebral cortex tissue. These results demonstrated that tetrahydroxystilbene glucoside as a natural drug might provide potential treatment for AD.

Characterization and expression profiling of glutathione S-transferases in the diamondback moth, Plutella xylostella (L.).

BACKGROUND: Glutathione S-transferases (GSTs) are multifunctional detoxification enzymes that play important roles in insects. The completion of several insect genome projects has enabled the identification and characterization of GST genes over recent years. This study presents a genome-wide investigation of the diamondback moth (DBM), Plutella xylostella, a species in which the GSTs are of special importance because this pest is highly resistant to many insecticides. RESULTS: A total of 22 putative cytosolic GSTs were identified from a published P. xylostella genome and grouped into 6 subclasses (with two unclassified). Delta, Epsilon and Omega GSTs were numerically superior with 5 genes for each of the subclasses. The resulting phylogenetic tree showed that the P. xylostella GSTs were all clustered into Lepidoptera-specific branches. Intron sites and phases as well as GSH binding sites were strongly conserved within each of the subclasses in the GSTs of P. xylostella. Transcriptome-, RNA-seq- and qRT-PCR-based analyses showed that the GST genes were developmental stage- and strain-specifically expressed. Most of the highly expressed genes in insecticide resistant strains were also predominantly expressed in the Malpighian tubules, midgut or epidermis. CONCLUSIONS: To date, this is the most comprehensive study on genome-wide identification, characterization and expression profiling of the GST family in P. xylostella. The diversified features and expression patterns of the GSTs are inferred to be associated with the capacity of this species to develop resistance to a wide range of pesticides and biological toxins. Our findings provide a base for functional research on specific GST genes, a better understanding of the evolution of insecticide resistance, and strategies for more sustainable management of the pest.

Tungsten tetraboride, an inexpensive superhard material.

Tungsten tetraboride (WB(4)) is an interesting candidate as a less expensive member of the growing group of superhard transition metal borides. WB(4) was successfully synthesized by arc melting from the elements. Characterization using powder X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) indicates that the as-synthesized material is phase pure. The zero-pressure bulk modulus, as measured by high-pressure X-ray diffraction for WB(4), is 339 GPa. Mechanical testing using microindentation gives a Vickers hardness of 43.3 ± 2.9 GPa under an applied load of 0.49 N. Various ratios of rhenium were added to WB(4) in an attempt to increase hardness. With the addition of 1 at.% Re, the Vickers hardness increased to approximately 50 GPa at 0.49 N. Powders of tungsten tetraboride with and without 1 at.% Re addition are thermally stable up to approximately 400 °C in air as measured by thermal gravimetric analysis.