What is the role of interface in the catalytic elimination of multi-carbon air pollutants?

Multi-carbon air pollutants pose serious hazards to the environment and health, especially soot and volatile organic compounds (VOCs). Catalytic oxidation is one of the most effective technologies for eliminating them. The oxidation of soot and most hydrocarbon VOCs begins with C-H (or edge-CH) activation, so this commonality can be targeted to design active sites. Rationally designed interface nanostructures optimize metal-support interactions (MSIs), providing suitable active sites for C-H activation. Meanwhile, the interfacial reactant spillover facilitates the further decomposition of activated intermediates. Thus, rationally exploiting interfacial effects is critical to enhancing catalytic activity. In this review, we analyzed recent advances in the following aspects: I. Understanding of the interface effects and design; II. Optimization of the catalyst-reactant contact, metal-support interface, and MSIs; III. Design of the interfacial composition and perimeter. Based on the analysis of the advances and current status, we provided challenges and opportunities for the rational design of interface nanostructures and interface-related stability. Meanwhile, a critical outlook was given on the interfacial sites of single-atom catalysts (SACs) for specific activation and catalytic selectivity.

[Advances in the production of chemicals by organelle compartmentalization in Saccharomyces cerevisiae]

As a generally-recognized-as-safe microorganism, Saccharomyces cerevisiae is a widely studied chassis cell for the production of high-value or bulk chemicals in the field of synthetic biology. In recent years, a large number of synthesis pathways of chemicals have been established and optimized in S. cerevisiae by various metabolic engineering strategies, and the production of some chemicals have shown the potential of commercialization. As a eukaryote, S. cerevisiae has a complete inner membrane system and complex organelle compartments, and these compartments generally have higher concentrations of the precursor substrates (such as acetyl-CoA in mitochondria), or have sufficient enzymes, cofactors and energy which are required for the synthesis of some chemicals. These features may provide a more suitable physical and chemical environment for the biosynthesis of the targeted chemicals. However, the structural features of different organelles hinder the synthesis of specific chemicals. In order to ameliorate the efficiency of product biosynthesis, researchers have carried out a number of targeted modifications to the organelles grounded on an in-depth analysis of the characteristics of different organelles and the suitability of the production of target chemicals biosynthesis pathway to the organelles. In this review, the reconstruction and optimization of the biosynthesis pathways for production of chemicals by organelle mitochondria, peroxisome, golgi apparatus, endoplasmic reticulum, lipid droplets and vacuole compartmentalization in S. cerevisiae are reviewed in-depth. Current difficulties, challenges and future perspectives are highlighted.

Enhancing Thermal Insulation of EPDM Ablators via Constructing Alternating Planar Architectures

Ethylene–propylene–diene monomer (EPDM) composites were usually enhanced with ablative additives to protect solid rocket motor (SRMs) casings. However, the poor thermal insulation caused by the high thermal conductive ablative fillers can lead to rocket motor failure. Herein, the novel EPDM composites containing alternating layers of ablative EPDM (AM) and heat-insulated EPDM (HM) were prepared through layer-multiplying extrusion. Compared with conventional EPDM ablative material, the multilayer composites showed enhanced thermal insulation and mechanical properties that could be further improved by tuning the number of layers. The ablation and thermal insulation properties possessing in AM and HM layers could be combined by forced assembly during co-extrusion, and the alternating multilayer composite was capable of showing the effect of each component. In particular, compared with AM, the maximum back-face temperature with 40 alternating layers of AM/HM decreased from 96.2 °C to 75.6 °C during oxyacetylene test, while the good ablation properties were preserved in the AM component. This significant improvement was attributed to the planar orientation and densification of ablative additives, and the interruption of conductive pathways in the through-plane direction of AM/HM alternating laminate. The anisotropic EPDM composites featuring mechanical robustness, good ablative resistance and thermal insulation suggest considerable potential application in the aerospace industry.

Understanding the Role of Carbon Fiber Skeletons in Silicone Rubber-Based Ablative Composites

At present, silicone rubber-based ablative composites are usually enhanced by carbon fibers (CFs) to protect the case of solid rocket motors (SRMs). However, the effect of the CFs’ length on the microstructure and ablation properties of the silicone rubber-based ablative composites has been ignored. In this work, different lengths of CFs were introduced into silicone rubber-based ablative composites to explore the effect of fiber length, and ceramic layers of various morphologies were constructed after ablation. It was found that a complete and continuous skeleton in ceramic layers was formed by CFs over 3 mm in length. In addition, the oxyacetylene ablation results showed that the linear ablation rate declined from 0.233 to 0.089 mm/s, and the maximum back-face temperature decreased from 117.7 to 107.9 °C as the length of the CFs increased from 0.5 to 3 mm. This can be attributed to the fact that successive skeletons concatenated and consolidated the ceramic fillers as well as residues to form an integrated, robust, and dense ceramic layer.

A novel method for peanut variety identification and classification by Improved VGG16

Crop variety identification is an essential link in seed detection, phenotype collection and scientific breeding. This paper takes peanut as an example to explore a new method for crop variety identification. Peanut is a crucial oil crop and cash crop. The yield and quality of different peanut varieties are different, so it is necessary to identify and classify different peanut varieties. The traditional image processing method of peanut variety identification needs to extract many features, which has defects such as intense subjectivity and insufficient generalization ability. Based on the deep learning technology, this paper improved the deep convolutional neural network VGG16 and applied the improved VGG16 to the identification and classification task of 12 varieties of peanuts. Firstly, the peanut pod images of 12 varieties obtained by the scanner were preprocessed with gray-scale, binarization, and ROI extraction to form a peanut pod data set with a total of 3365 images of 12 varieties. A series of improvements have been made to VGG16. Remove the F6 and F7 fully connected layers of VGG16. Add Conv6 and Global Average Pooling Layer. The three convolutional layers of conv5 have changed into Depth Concatenation and add the Batch Normalization(BN) layers to the model. Besides, fine-tuning is carried out based on the improved VGG16. We adjusted the location of the BN layers. Adjust the number of filters for Conv6. Finally, the improved VGG16 model's training test results were compared with the other classic models, AlexNet, VGG16, GoogLeNet, ResNet18, ResNet50, SqueezeNet, DenseNet201 and MobileNetv2 verify its superiority. The average accuracy of the improved VGG16 model on the peanut pods test set was 96.7%, which was 8.9% higher than that of VGG16, and 1.6–12.3% higher than that of other classical models. Besides, supplementary experiments were carried out to prove the robustness and generality of the improved VGG16. The improved VGG16 was applied to the identification and classification of seven corn grain varieties with the same method and an average accuracy of 90.1% was achieved. The experimental results show that the improved VGG16 proposed in this paper can identify and classify peanut pods of different varieties, proving the feasibility of a convolutional neural network in variety identification and classification. The model proposed in this experiment has a positive significance for exploring other Crop variety identification and classification.

[Progress in studies on production of chemicals from xylose by Saccharomyces cerevisiae]

Effective utilization of xylose is a basis for economic production of biofuels or chemicals from lignocellulose biomass. Over the past 30 years, through metabolic engineering, evolutionary engineering and other strategies, the metabolic capacity of xylose of the traditional ethanol-producing microorganism Saccharomyces cerevisiae has been significantly improved. In recent years, the reported results showed that the transcriptome and metabolome profiles between xylose and glucose metabolism existed significant difference in recombinant yeast strains. Compared with glucose, the overall process of xylose metabolism exhibits Crabtree-negative characteristics, including the limited glycolytic pathway activity, which reduces the metabolic flux of pyruvate to ethanol, and the enhanced cytosolic acetyl-CoA synthesis and respiratory energy metabolism. These traits are helpful to achieve efficient synthesis of downstream products using pyruvate or acetyl-CoA as precursors. This review provides a detailed overview on the modification and optimization of xylose metabolic pathways in S. cerevisiae, the characteristics of xylose metabolism, and the construction of cell factories for production of chemicals using xylose as a carbon source. Meanwhile, the existed difficulties and challenges, and future studies on biosynthesis of bulk chemicals using xylose as an important carbon source are proposed.

MicroRNA 449c Mediates the Generation of Monocytic Myeloid-Derived Suppressor Cells by Targeting STAT6

Myeloid-derived suppressor cells (MDSCs) promote tumour progression by contributing to angiogenesis, immunosuppression, and immunotherapy resistance. Although recent studies have shown that microRNAs (miRNAs) can promote the expansion of MDSCs in the tumour environment, the mechanisms involved in this process are largely unknown. Here, we report that microRNA 449c (miR-449c) expression was upregulated in myeloid progenitor cells upon activation of C-X-C motif chemokine receptor 2 (CXCR2) under tumour conditions. MiR-449c upregulation increased the generation of monocytic MDSCs (mo-MDSCs). The increased expression of miR-449c could target STAT6 mRNA in myeloid progenitor cells to shift the differentiation balance of myeloid progenitor cells and lead to an enhancement of the mo-MDSCs population in the tumour environment. Thus, our results demonstrate that the miR-449c/STAT6 axis is involved in the expansion of mo-MDSCs from myeloid progenitor cells upon activation of CXCR2, and thus, inhibition of miR-449c/STAT6 signalling may help to attenuate tumour progression.

Influence of miR-34a on preeclampsia through the Notch signaling pathway

OBJECTIVE

The aim of this study was to investigate the influence of micro-ribonucleic acid-34a (miR-34a) on preeclampsia through the Notch signaling pathway.

PATIENTS AND METHODS

The expressions of miR-34a, Notch-1, Notch-2, and Notch-3 in the placenta of 39 preeclampsia patients and 42 normal patients were detected by immunohistochemistry and Reverse Transcription-Polymerase Chain Reaction (RT-PCR). The correlations between miR-34a expression with the expressions of Notch-1, Notch-2 and Notch-3 were analyzed, respectively. Besides, placental trophoblasts were isolated from preeclampsia patients and cultured in vitro. The expressions of miR-34a, Notch-1, Notch-2 and Notch-3 in placental trophoblasts were analyzed. Furthermore, the influences of miR-34a on the protein expressions of Notch-1, Notch-2, Notch-3, and hairy and enhancer of split-1 (Hes-1) in the Notch signaling pathway were analyzed by Luciferase reporter gene assay and Western blotting. The role of Notch in trophoblast invasion was investigated through the Notch inhibitors. In addition, its influence on the expression of urokinase-type plasminogen activator (uPA) was studied by miR-34a overexpression.

RESULTS

The expressions of miR-34a and Notch-1 were correlated with preeclampsia in the placentas of preeclampsia patients and normal patients to a certain degree. The expression of miR-34a in preeclamptic placenta was significantly higher than that of the normal placenta (p<0.05). However, Notch-1 expression was markedly lower in preeclamptic placenta (p<0.05). No significant differences were found in the expressions of Notch-2 and Notch-3 between the two types of placentas (p>0.05). MiR-34a had a remarkable negative correlation with Notch-1 expression in the Notch family (p<0.001, r=-0.5775). RT-PCR results revealed that the mRNA expression of miR-34a in placental trophoblasts of patients with preeclampsia was notably higher than that of normal people (p<0.01). However, Western blotting demonstrated that the protein expressions of Notch-1, Notch-2 and Notch-3 exhibited the opposite results. Additionally, the protein expression of Notch-1, Notch-2, Notch-3 and Hes-1 in trophoblasts transfected with pre-miR-34a was significantly decreased. The treatment with Notch inhibitors markedly reduced the trophoblast invasion. Furthermore, miR-34a overexpression or intracellular domain of Notch (ICN) overexpression regulated uPA expression.

CONCLUSIONS

MiR-34a regulates uPA system through the Notch signal transduction, thereby regulating the invasion of placental trophoblasts in patients with preeclampsia.

Preparation of Silver Sulfadiazine Loaded Pectin-Zinc Nanocomposites for Improvement of Antioxidant, Antibacterial and Care Cutaneous Wound Care During the Perioperative Period

Medicinal care for cutaneous wound becomes difficult due to the emergence of antibiotic resistant bacteria. The development of a new cost-effective drug based on silver sulfadiazine loaded with pectin-zinc nanocomposites offers better therapeutics in wound healing besides its role in enhancing antioxidant and antibacterial activities. In this study, silver sulfadiazine loaded with pectin-zinc nanocomposites (AgSD-PC-Zn) was produced and its antioxidant and antimicrobial properties were tested against wound infection causing bacterial pathogens (S. aureus and E. coli). The synthesized AgSD-PC-Zn composite was biophysically characterized. TEM analysis confirmed the spherical shape of NPs. AgSD-PC-Zn composite exhibited a greater antibacterial effect against S. aureus and E. coli. The number of dead bacterial cells was higher after exposure to AgSD-PC-Zn composite. Furthermore, in vitro antioxidant enzyme activities (DPPH and H2O2) were increased with AgSDPC-Zn composite. A rapid healing of the skin wounds in mouse was noticed with AgSD-PC-Zn composite treatment. This study concludes that the newly formed AgSD-PC-Zn composite will act as a strong antimicrobial and antioxidant agents for treating skin wound infection.

A meta-analysis of influence of MSMB promoter rs10993994 polymorphisms on prostate cancer risk

OBJECTIVE

The aim of this meta-analysis was to assess the association between beta-microseminoprotein gene (MSMB) rs10993994 polymorphism and prostate cancer (PCa) risk.

MATERIALS AND METHODS

Relevant databases were searched to identify studies investigating the association between rs10993994 polymorphisms and the risk of PCa using allele contrast, recessive, dominant, and additive models. The assessment of the association was used by odds ratios (ORs) with 95% confidence intervals (CIs). Hardy-Weinberg equilibrium (HWE) was checked for each study. The sensitivity analysis and the assessment of publication bias were also performed.

RESULTS

Six reports involving 13 eligible studies (a total of 11,385 PCa patients and 9,115 controls) were included in the meta-analysis. Our data revealed that the T allele of MSMB rs10993994 polymorphism was significantly associated with PCa in all subjects (allele contrast: OR=1.24, 95% CI=1.19-1.29, p<0.001). Similarly, for recessive, dominant, and additive genetic models, significant associations were also found (recessive: OR=1.40, 95% CI=1.30-1.51; dominant: OR=1.28, 95% CI=1.21-1.36; and additive: OR=1.56, 95% CI=1.44-1.70). Significant associations were also found in Caucasians. The data for Asians showed significant association in allele contrast and recessive, additive genetic models, whereas no statistical significance was found in the dominant genetic model.

CONCLUSIONS

This study demonstrated a significant association between the MSMB rs10993994 polymorphisms and PCa risk. Further large-scale studies are warranted to confirm our findings.

CXCR2 expression on granulocyte and macrophage progenitors under tumor conditions contributes to mo-MDSC generation via SAP18/ERK/STAT3

Myeloid-derived suppressor cells (MDSCs) comprise a critical component of the tumor environment and CXCR2 reportedly plays a key role in the pathophysiology of various inflammatory diseases. Here, CXCR2 expression on granulocyte and macrophage progenitor cells (GMPs) was found to participate in myeloid cell differentiation within the tumor environment. In CXCR2-deficient tumor-bearing mice, GMPs exhibited fewer macrophage and dendritic cell progenitor cells than wild-type tumor-bearing mice, thereby decreasing monocytic MDSCs (mo-MDSCs) expansion. CXCR2 deficiency increased SAP18 expression in tumor-bearing mice, which reduced STAT3 phosphorylation through restraining ERK1/2 activation. Our findings reveal a critical role for CXCR2 in regulating hematopoietic progenitor cell differentiation under tumor conditions, and SAP18 is a key negative regulator in this process. Thus, inhibiting CXCR2 expression may alter the tumor microenvironment and attenuate tumor progression.

[Regulation of Smad ubiquitination regulatory factor 1 expression by NF-κB]

OBJECTIVE

To identify a nuclear factor κB (NF-κB) responsive element within the Smad ubiquitination regulatory factor 1 (SMURF1) gene promoter, and to demonstrate its role in the regulation of SMURF1 expression.

METHODS

A series of truncated luciferase reporter plasmids of the SMURF1 promoter were constructed and transfected into hepatic cancer Hep G2 cells. Luciferase assays were carried out to assess the activities of such promoters. DNA binding and chromatin immunoprecipitation (ChIP) assays were used to identify an NF-κB responsive element within the SMURF1 promoter. Lucifease plasmid with mutated NF-κB site was constructed and its activity was assessed. The expression of SMURF1 in Hep G2 cells was detected after transfection of NF-κB specific small interfering RNA (siRNA).

RESULTS

The SMURF1 promoter showed a high transcription activity, and the region of -519 to -378 was demonstrated to be a positive regulatory region. -411 to -420 of the SMURF1 promoter was an NF-κB responsive element, and NF-κB may specifically bind to this site. Mutation of this element may prominently decrease the activity of the promoter. Transfection of NF-κB siRNA evidently down-regulated SMURF1 expression.

CONCLUSION

NF-κB can specifically bind to the -411 to -420 region of the SMURF1 promoter and plays an essential role in the expression of SMURF1.

[Analysis of the vacuum sealing drainage technique combined with sural neurovascular pedicle fascio-cutaneous flap to repair deep wounds in the foot near the ankle joint with exposed bone and tendons]

OBJECTIVE

To evaluate the practical method of vacuum sealing drainage (VSD) technique combined with sural neurovascular pedicle fasciocutaneous flap to repair deep wounds in the foot near the ankle joint with exposed bone and tendons.

METHODS

From January 2006 to January 2009, 79 patients with deep wounds in the foot near the ankle joint with exposed bone and tendons were treated by VSD technique combined with sural neurovascular pedicle fasciocutaneous flap including 58 males and 21 females with an average age of 34 years old ranging from 7 to 59 years. There were 17 cases in low 1/3 part of leg and achilles tendon, 28 in lateral malleolus and lateral dorsum of foot, 21 in medial malleolus and medial dorsum of foot, 13 in heel and pelma. Firstly the wounds were debrided and cultivated by using VSD technique, then the soft tissue defections were repaired with sural neurovascular pedicle fasciocutaneous flap.

RESULTS

The area of flap was from 6 cm x 5 cm to 18 cm x 15 cm; All patients stayed in hospital for 14 to 30 days, 18 days in average. Living flaps of all patients were followed-up from 6 months to 3 years, the flaps of 2 patients were mostly necrotic, 3 were necrotic, 5 cases appeared obstacle of venous back streaming. The others survived with no infections.

CONCLUSION

The wound would become fresh and clean as soon as possible with VSD. The sural neurovascular pedicle fasciocutaneous flap could provide a good covering for the exposed wound. Therefore the wound healed faster with friction resistance and fine appearance. The time of hospitalization were greatly shortened after combined application.

Trephine arthrodesis of subtalar joints: operative technique and clinical effect

OBJECTIVE

To review the operative technique of trephine arthrodesis of subtalar joints and evaluate its clinical effect.

METHODS

From June 1998 to October 2006, we performed subtalar arthrodesis on 38 feet of 34 patients for a variety of painful disorders of hindfoot with trephine technique. Clinical and radiologic follow-up evaluations were performed for 45 months on average (range, 21 to 110 months) after arthrodesis.

RESULTS

No severe complications were found in this study except one patient with dropfoot and two with skin necrosis. The average ankle-hindfoot scores of the American Orthopaedic Foot and Ankle Society (AOFAS) was improved from 48.3 preoperatively to 79.2 postoperatively (P<0.05). The pain scores of visual analogue scales (VAS) decreased from 7.2 (range, 3 to 10) preoperatively to 2.6 (range, 1 to 6) postoperatively (P<0.05). Subjectively, the patients experienced improvements in pain, function, cosmesis, and shoewearing. Overall, 30 patients were satisfied and all patients would have this procedure again under similar circumstances. Postoperative radiology showed that complete union was found in 35 feet 6 months after operation, with the successful union rate of 92.1%. There was an increase in arthritic scores for 5 ankles, 4 talonavicular joints, 4 calcaneocuboid joints, and 4 midfoot joints. Nonunion occurred in 3 subtalar joints with anterolateral approach, which required revision arthrodesis.

CONCLUSION

Isolated subtalar arthrodesis with trephine method is an effective procedure for painful malalignment of hindfoot.

Optimization of resolution and sensitivity of 4D NOESY using multi-dimensional decomposition

Highly resolved multi-dimensional NOE data are essential for rapid and accurate determination of spatial protein structures such as in structural genomics projects. Four-dimensional spectra contain almost no spectral overlap inherently present in lower dimensionality spectra and are highly amenable to application of automated routines for spectral resonance location and assignment. However, a high resolution 4D data set using conventional uniform sampling usually requires unacceptably long measurement time. Recently we have reported that the use of non-uniform sampling and multi-dimensional decomposition (MDD) can remedy this problem. Here we validate accuracy and robustness of the method, and demonstrate its usefulness for fully protonated protein samples. The method was applied to 11 kDa protein PA1123 from structural genomics pipeline. A systematic evaluation of spectral reconstructions obtained using 15-100% subsets of the complete reference 4D 1H-13C-13C-1H NOESY spectrum has been performed. With the experimental time saving of up to six times, the resolution and the sensitivity per unit time is shown to be similar to that of the fully recorded spectrum. For the 30% data subset we demonstrate that the intensities in the reconstructed and reference 4D spectra correspond with a correlation coefficient of 0.997 in the full range of spectral amplitudes. Intensities of the strong, middle and weak cross-peaks correlate with coefficients 0.9997, 0.9965, and 0.83. The method does not produce false peaks. 2% of weak peaks lost in the 30% reconstruction is in line with theoretically expected noise increase for the shorter measurement time. Together with good accuracy in the relative line-widths these translate to reliable distance constrains derived from sparsely sampled, high resolution 4D NOESY data.