Image super‐resolution via dynamic network

Convolutional neural networks depend on deep network architectures to extract accurate information for image super‐resolution.However,obtained information of these con-volutional neural networks cannot completely express predicted high‐quality images for complex scenes.A dynamic network for image super‐resolution(DSRNet)is presented,which contains a residual enhancement block,wide enhancement block,feature refine-ment block and construction block.The residual enhancement block is composed of a residual enhanced architecture to facilitate hierarchical features for image super‐resolution.To enhance robustness of obtained super‐resolution model for complex scenes,a wide enhancement block achieves a dynamic architecture to learn more robust information to enhance applicability of an obtained super‐resolution model for varying scenes.To prevent interference of components in a wide enhancement block,a refine-ment block utilises a stacked architecture to accurately learn obtained features.Also,a residual learning operation is embedded in the refinement block to prevent long‐term dependency problem.Finally,a construction block is responsible for reconstructing high‐quality images.Designed heterogeneous architecture can not only facilitate richer structural information,but also be lightweight,which is suitable for mobile digital devices.Experimental results show that our method is more competitive in terms of performance,recovering time of image super‐resolution and complexity.The code of DSRNet can be obtained at https://github.com/hellloxiaotian/DSRNet.

A unique role of the pyrimidine de novo synthesis enzyme ODCase in Lysobacter enzymogenes

Bacterial species of the genus Lysobacter are environmentally ubiquitous with strong antifungal biocontrol potential.Heat-stable antifungal factor(HSAF)secreted by the biocontrol bacterium Lysobacter enzymogenes OH11 has broad-spectrum and highly efficient antifungal activity.Studying the biosynthetic regulations of HSAF would lay an important foundation for strain engineering toward improved HSAF production.In this work,we demonstrate that Le0752,an orotidine-5´-phosphate decarboxylase enzyme(ODCase)catalyzing a pivotal step of the UMP de novo biosynthesis pathway,is vital for HSAF-mediated antimicrobial activities and growth of L.enzymogenes OH11,but not for twitching motility.This gene regulates the production of HSAF by affecting the expression of lafB,a key gene in the HSAF biosynthesis operon,through the transcription factor Clp.Interestingly,bioinformatics analysis revealed that Le0752 belongs to the Group III ODCases,whereas its homologs in the closely related genera Xanthomonas and Stenotrophomonas belong to Group I,which contains most ODCases from Gram-positive bacteria,Gram-negative bacteria and cyanobacteria.Moreover,the Group I ODCase PXO_3614 from the Xanthomonas oryzae pv.oryzae PXO99A strain complemented the Le0752 mutant in regulating HSAF-mediated antagonistic activity.Together,these results highlight the important requirement of de novo pyrimidine biosynthetic enzymes for antibiotic HSAF production in L.enzymogenes,which lays an important foundation for improving HSAF production via metabolic flow design and for dissecting the regulatory functions of bacterial ODCases.

Chrysophanol inhibits the progression of gastric cancer by activating nod-like receptor protein-3

Aim:Gastric cancer(GC)is one of the most common malignant tumors.Chrysophanol has been reported to possess antitumor effects on a variety of cancers;however,its role in GC remains unclear.This study aimed to investigate the effects of chrysophanol on the proliferation,pyroptosis,migration,and invasion of GC cells.Methods:Human GC cell lines MKN 28 and AGS cells were treated with different concentrations of chrysophanol,then cell proliferation,migration,invasion and pyroptosis were determined by CCK-8,colony-forming assay,wound healing assay,Transwell assay,and flow cytometry.Cell migration and invasion were reassessed in these transfected cells following the transfection of nod-like receptor protein-3(NLRP3)siRNA in MKN 28 and AGS cells.To examine the downstream signaling pathway of the NLRP3 signaling pathway,NLRP3,caspase-1,gasdermin-D,interleukin(IL)-1β,and IL-18 were detected by quantitative real-time-polymerase chain reaction or western blotting.Results:Chrysophanol inhibited the proliferation of GC cells,caused pyroptosis,inhibited cell migration and invasion,and increased the expression of NLRP3 inflammasomes in GC cells.Knockdown of NLRP3 inhibited the effects of chrysophanol on proliferation,pyroptosis,migration,and invasion of GC cells.Chrysophanol plays an anticancer role by enhancing NLRP3.Conclusions:Chrysophanol exerts anti-neoplastic effects in vitro in GC cells by modulating NLRP3,thus highlighting its therapeutic potential in GC.

Lactobacillus reuteri-derived extracellular vesicles maintain intestinal immune homeostasis against lipopolysaccharideinduced inflammatory responses in broilers

Background:Lactobacillus reuteri strains are widely used as probiotics to prevent and treat inflammatory bowel disease by modulating the host’s immune system.However,the underlying mechanisms by which they communicate with the host have not been clearly understood.Bacterial extracellular vesicles(EVs)have been considered as important mediators of host-pathogen interactions,but their potential role in commensals-host crosstalk has not been widely studied.Here,we investigated the regulatory actions of EVs produced by L.reuteri BBC3,a gut-associated commensal bacterium of Black-Bone chicken,in the development of lipopolysaccharide(LPS)-induced intestinal inflammation in a chicken model using both in vivo and in vitro experiments.Results:L.reuteri BBC3 produced nano-scale membrane vesicles with the size range of 60-250 nm.Biochemical and proteomic analyses showed that L.reuteri BBC3-derived EVs(LrEVs)carried DNA,RNA and several bioactive proteins previously described as mediators of other probiotics’beneficial effects such as glucosyltransferase,serine protease and elongation factor Tu.In vivo broiler experiments showed that administration of LrEVs exerted similar effects as L.reuteri BBC3 in attenuating LPS-induced inflammation by improving growth performance,reducing mortality and decreasing intestinal injury.LrEVs suppressed the LPS-induced expression of pro-inflammatory genes(TNF-α,IL-1β,IL-6,IL-17 and IL-8),and improved the expression of anti-inflammatory genes(IL-10 and TGF-β)in the jejunum.LrEVs could be internalized by chicken macrophages.In vitro pretreatment with LrEVs reduced the gene expression of TNF-α,IL-1βand IL-6 by suppressing the NF-κB activity,and enhanced the gene expression of IL-10 and TGF-βin LPS-activated chicken macrophages.Additionally,LrEVs could inhibit Th1-and Th17-mediated inflammatory responses and enhance the immunoregulatory cells-mediated immunosuppression in splenic lymphocytes of LPS-challenged chickens through the activation of macrophages.Finally,we revealed that the reduced content of both vesicular proteins and nucleic acids attenuated the suppression of LrEVs on LPS-induced inflammatory responses in ex vivo experiments,suggesting that they are essential for the LrEVs-mediated immunoregulation.Conclusions:We revealed that LrEVs participated in maintaining intestinal immune homeostasis against LPSinduced inflammatory responses in a chicken model.Our findings provide mechanistic insight into how commensal and probiotic Lactobacillus species modulate the host’s immune system in pathogens-induced inflammation.

Mobile power generation system based on biomass gasifcation

Disaster-hit and/or un-electrifed remote areas usually have electricity accessibility issues and an abundance of plant-derived debris and wood from destroyed wooden structures;this can be potentially addressed by employing a decentralized ultrasmall biomass-fed gasifcation power generating system.This paper presents an assessment of the technical viability of an ultra-small gasifcation system that utilizes densifed carbonized wood pellets/briquettes.The setup was run continuously for 100 h.A variety of biomass was densifed and carbonized by harnessing fugitive heat sources before charging into the reactor.Carbonized briquettes and furnished blends exhibited inferior gasifcation performance compared to the carbonized pellets.In the absence of tar blockage problems,steady-state conditions were achieved when pre-treated feedstock was used.Under steady-state conditions for carbonized pellets gasifcation operated at an equivalence ratio of 0.32,cold gas efciency and carbon conversion achieved 49.2%and 70.5%,respectively.Overall efciency and maximum power output of 20.3%and 21 kW were realised,respectively.It was found that the system could keep stable while the low heating valve of syngas was over 4 MJ/m^(3)on condition that avoiding tar blocking issues.The results indicate that the proposed compact ultra-small power generation system is a technically feasible approach to remedy power shortage challenge.In addition,process simulation considering carbonized wood gasifcation combined power generation was formulated to produce syngas and electricity.Woody pellets with the fow rate of 20 kg/h could generate a 15.18 kW power at the air fow rate of 40 Nm^(3)/h,which is in a good agreement with 15 kW in the 100 h operation.It is indicated that the gasifcation combined power generation cycle simulated by Aspen simulator could achieve reliable data to assist the complicated experiment operation.

Association of Apolipoprotein E Gene Polymorphism with Lipid Profile in Patients with Acute Coronary Syndrome in Han Chinese: A Critical Review

This review paper focuses on the genetic contribution, in particular, the association of Apolipoprotein E gene polymorphism to lipid abnormality and subsequent acute coronary syndrome in Han Chinese of China. Many researches have been published pertaining the influence of ApoE gene polymorphism on coronary artery disease, dyslipidemia and the response of statin in Han Chinese. Most of the studies in Han Chinese like other populations demonstrated that ApoE 4 allele genetically predisposes coronary artery disease, acute coronary syndrome, severity of occlusion of coronary artery and higher incidence of major adverse cardiovascular events (In Han Chinese, ApoE allele carriers demonstrated 85% increase in major adverse cardiovascular events (MACE) in six months follow up). In addition, ApoE4 allele carrier also showed both increased in LDL level and decrease response to statin therapy in dyslipidemic Han Chinese. On the other hand, ApoE2 carrier is scavenger of cholesterol and triglyceride from the blood;?thus it is cardiovascular-protective. Despite positive relationship between ApoE gene polymorphism and cardiovascular pathologies, prognostic outcome and resistance to intervention, this area of research still requires?extensive investigation in Han Chinese. Because, several other studies revealed either negative effect or showed no effect by ApoE gene polymorphism on cardiovascular disease. Some of the causes of such debatable results could be explained by factors such as diminutive frequency allele and expression of ApoE gene in coronary heart disease. This part of the research yet requires extensive study with bulkier sample size and retrospective in nature, in order to ascertain the influence of ApoE genotype on lipid, anti-hyperlipidemic agent and coronary heart disease. Such studies could assist us to confirm whether to test healthier subjects to predict genetic risk of coronary heart disease in Han Chinese population. The aim of this review paper is to critically analyze the effect of ApoE gene on the occurrence of coronary heart disease in Han Chinese.

Feature Selection Based on Distance Measurement

Every day we receive a large amount of information through different social media and software,and this data and information can be realized with the advent of data mining methods.In the process of data mining,to solve some high-dimensional problems,feature selection is carried out in limited training samples,and effective features are selected.This paper focuses on two Relief feature selection algorithms:Relief and ReliefF algorithm.The differences between them and their respective applicable scopes are analyzed.Based on Relief algorithm,the high weight feature subset is obtained,and the correlation between features is calculated according to the mutual information distance measure,and the high redundant features are removed to obtain the feature subset with higher quality.Experimental results on six datasets show the effectiveness of our method.

Impact of Baseline LDL-C and Lp(a) Elevation on Coronary Revascularization in Patients with Acute Coronary Syndrome One-Year after First Percutaneous Coronary Intervention

Objective: The aim of this study was to investigate the effect of Lipoprotein-a [Lp(a)] on Coronary Revascularizaton (CR) on one year follow up in patients with Acute Coronary Syndrome (ACS) after the first Percutaneous Coronary Intervention (PCI). Method: A retrospective study was designed. A total of 475 patients that underwent their first PCI treatment due to ACS between January 2016 and December 2017 were recruited and followed for one year at the Zhongda Hospital, China. The clinical end point after first PCI was prevalence of Major Adverse Cardiovascular Events (MACE) including nonfatal Myocardial Infarction (MI), cardiovascular death, ischemic stroke and Coronary Revascularization (CR). According to the cut point of Lp(a), participants were divided into low Lp(a) subgroup (Lp(a) mg/L) and high Lp(a) subgroup (Lp(a) ≥ 300 mg/L). Furthermore, based on baseline Low Density Lipoprotein Cholesterol (LDL-C) level, participants were divided into low LDL-C (LDL-C mmol/L) and high LDL-C (LDL-C ≥ 1.8 mmol/L) subgroups. Results: The number of prevalence of CR was higher with elevated serum Lp(a) in both low LDL-C subgroup and high LDL-C subgroup, and was significantly different in both the low LDL-C subgroup and high LDL-C subgroup (p = 0.009 and p = 0.006, respectively). Multivariate Cox-hazard regression analysis for CR showed increase in serum LDL-C and Lp(a) increased prevalence of CR by 1.514 and 1.002 folds respectively. Furthermore, Kaplan-Meier cumulative survival curves showed that increased prevalence of CR within one year after first PCI in patients with high Lp(a) [log rank p = 0.000]. Conclusion: Baseline increase of serum LDL-C and Lp(a) significantly increases the prevalence of CR after first PCI within one year. It indicates that after PCI treatment, in patient with serum LDL-C and Lp(a) elevation, treatment with high-dose statin therapy or PCSK9 inhibitors may alleviate the adverse effects imposed by Lp(a) elevation.

Experimental and numerical modeling of carbonized biomass gasification: A critical review

Gasification is one of the most significant and well-researched pathways to produce energy from biomass among the different options available.It is a conversion through thermo-chemical process that takes place within a gasifier,with interconnected factors that have an impact on how well the gasifier works.Gasification of carbonized biomass,which has a variety of effects on both the gasification process and the final product,is a significant method of producing energy from raw biomass that contains a lot of moisture or has non-homogeneous morphology.Although carbonized biomass has the potential to eliminate or significantly reduce tar formation,which is the most difficult aspect of biomass gasifier design and operation,it has not received the attention it merits even though gasification of biomass is a well-known conversion process with extensive research and development spanning all sectors of the process.This review gathers and analyzes the growing number of experimental and numerical modeling approaches in gasification of carbonized biomass based on exact conditions such as type of modeling considerations,feedstock,gasifier,and assessed parameters.The study also provides an overview of various models,such as equilibrium and kinetic rate models and numerical simulations of carbonized biomass gasification schemes based on computational fluid dynamics and Aspen Plus,while comparing the modeling approaches and results for each type of models that are described in the literature.Also,this review encompasses a broad variety of technologies,from laboratory reactors to industrial scale.Overall,this review offers a brief overview of the modeling decisions that must be taken at the beginning of a modeling research.

Single-cell-resolution transcriptome map revealed novel genes involved in testicular germ cell progression and somatic cells specification in Chinese tongue sole with sex reversal

Female-to-male sex reversals(pseudomales)are common in lower vertebrates and have been found in natural populations,which is a concern under rapid changes in environmental conditions.Pseudomales can exhibit altered spermatogenesis.However,the regulatory mechanisms underlying pseudomale spermatogenesis remain unclear.Here,we characterized spermatogenesis in Chinese tongue sole(Cynoglossus semilaevis),a species with genetic and environmental sex determination,based on a highresolution single-cell RNA-seq atlas of cells derived from the testes of genotypic males and pseudomales.We identified five germ cell types and six somatic cell types and obtained a single-cell atlas of dynamic changes in gene expression during spermatogenesis in Chinese tongue sole,including alterations in pseudomales.We detected decreased levels of Ca^(2+)signaling pathway-related genes in spermatogonia,insufficient meiotic initiation in spermatocytes,and a malfunction of somatic niche cells in pseudomales.However,a cluster of CaSR genes and MAPK signaling factors were upregulated in undifferentiated spermatogonia of pseudomales.Additionally,we revealed that Z chromosome-specific genes,such as piwil2,dhx37,and ehmt1,were important for spermatogenesis.These results improve our understanding of reproduction after female-to-male sex-reversal and provide new insights into the adaptability of reproductive strategies in lower vertebrates.

Halloysite‒gold core‒shell nanosystem synergistically enhances thermal conductivity and mechanical properties to optimize the wear-resistance of a pheonlic-PBO/PTFE textile composite liner

Polymer-textile liner composites have potential applications in aerospace applications for reducing the abrasion damage of moving parts during operation owing to their self-lubrication,light weight,and high loading capacity.Herein,Au nanoparticles(AuNPs)are successfully loaded into the lumen of halloysite nanotubes(HNTs)to construct an HNTs‒Au peasecod core‒shell nanosystem to optimize the wear resistance of phenolic resin-based poly(p-phenylene benzobisoxazole)(PBO)/polytetrafluoroethylene(PTFE)textile composites.Transmission electron microscope(TEM)characterization reveals that the AuNPs are well-dispersed inside the HNTs,with an average diameter of 6‒9 nm.The anti-wear performance of the HNTs and Au-reinforced PBO/PTFE composites is evaluated using a pin-on-disk friction tester at 100 MPa.Evidently,the addition of HNTs‒Au induces a 27.9%decrease in the wear rate of the composites.Possible anti-wear mechanisms are proposed based on the analyzed results of the worn surface morphology and the cross-section of the tribofilm obtained by focused ion beam transmission electron microscopy.

Corrigendum to “Sox9 augments BMP2-induced chondrogenic differentiation by downregulating Smad7 in mesenchymal stem cells (MSCs)” [Genes & Diseases 4 (2017) 229–239]

The authors regret having image assembly errors in Figure 1A and Figure 3A.Specifically,in Figure 1A,the images for"C3H10T1/2",""BMP2"and"Sox9"were erroneously duplicated with the images from an irrelevant experiment that was conducted at the same time.In Figure 3A,the images for"Col2a1"and"β-actin"were erroneously duplicated with the images from an irrelevant experiment that was conducted at the same time.

Friction and wear behaviors of MoS2-multi-walled-carbonnanotube hybrid reinforced polyurethane composite coating

MoS2-multi-walled-carbon-nanotube(MWCNT)hybrids containing two-dimensional MoS2 and one-dimensional MWCNTs were synthesized through a one-step hydrothermal reaction.X-ray-diffraction and transmission-electron-microscopy results demonstrated that MoS2 nanosheets were successfully synthesized,and uniformly anchored on the MWCNTs’surfaces.Furthermore,the effects of the Mo S2-MWCNT hybrids on the tribological performances of polyurethane composite coatings were investigated using a UMT-2MT tribo-tester.Friction and wear test results revealed that the friction coefficient and wear rate of a 3 wt%Mo S2-MWCNT-1 filled polyurethane composite coating were reduced by 25.6% and 65.5%,respectively.The outstanding tribological performance of the MoS2-MWCNT-1 reinforced polyurethane composite coating was attributed to the excellent load-carrying capacity of the MWCNTs and good lubricant ability of MoS2.The surface morphologies of the worn surfaces and counterpart ball surfaces were investigated to reveal the wear mechanisms.

Sox9 augments BMP2-induced chondrogenic differentiation by downregulating Smad7 in mesenchymal stem cells(MSCs)

Cartilage injuries caused by arthritis or trauma pose formidable challenges for effective clinical management due to the limited intrinsic proliferative capability of chondrocytes.Autologous stem cell-based therapies and transgene-enhanced cartilage tissue engineering may open new avenues for the treatment of cartilage injuries.Bone morphogenetic protein 2(BMP2)induces effective chondrogenesis of mesenchymal stem cells(MSCs)and can thus be explored as a potential therapeutic agent for cartilage defect repair.However,BMP2 also induces robust endochondral ossification.Although the precise mechanisms through which BMP2 governs the divergence of chondrogenesis and osteogenesis remain to be fully understood,blocking endochondral ossification during BMP2-induced cartilage formation may have practical significance for cartilage tissue engineering.Here,we investigate the role of Sox9-donwregulated Smad7 in BMP2-induced chondrogenic differentiation of MSCs.We find that overexpression of Sox9 leads to a decrease in BMP2-induced Smad7 expression in MSCs.Sox9 inhibits BMP2-induced expression of osteopontin while enhancing the expression of chondrogenic marker Col2a1 in MSCs.Forced expression of Sox9 in MSCs promotes BMP2-induced chondrogenesis and suppresses BMP2-induced endochondral ossification.Constitutive Smad7 expression inhibits BMP2-induced chondrogenesis in stem cell implantation assay.Mouse limb explant assay reveals that Sox9 expands BMP2-stimulated chondrocyte proliferating zone while Smad7 promotes BMP2-intitated hypertrophic zone of the growth plate.Cell cycle analysis indicates that Smad7 induces significant early apoptosis in BMP2-stimulated MSCs.Taken together,our results strongly suggest that Sox9 may facilitate BMP2-induced chondrogenesis by downregulating Smad7,which can be exploited for effective cartilage tissue engineering.

In situ reduction and functionalization of graphene oxide to improve the tribological behavior of a phenol formaldehyde composite coating

The development of a phenol formaldehyde/graphene(PF-graphene)composite coating with high performance is desirable but remains a challenge,because of the ultrahigh surface area and surface inertia of the graphene.Herein,we synthesized PF-graphene composites by the in situ polymerization of phenol and formaldehyde with the addition of graphene oxide,resulting in improved compatibility between the graphene and phenolic resin(PF)matrix and endowing the phenolic resin with good thermal stability and excellent tribological properties.Fourier-transform infrared(FTIR)spectra and X-ray diffraction(XRD)patterns demonstrated that the graphene oxide was reduced during the in-situ polymerization.The PF-graphene composites were sprayed onto steel blocks to form composite coatings.The effects of an applied load and of the sliding speed on the tribological properties of the PF-graphene composite coating were evaluated using a block-on-ring wear tester;in addition,the worn surface and the transfer film formed on the surface of the counterpart ring were studied by scanning electron microscopy(SEM).The results show that the PF-graphene composite coating exhibited enhanced tribological properties under all tested conditions.

Combined effects of interface modification and micro-filler reinforcements on the thermal and tribological performances of fabric composites

The high specific‐strength of glass fibers and exceptional self‐lubrication of polytetrafluoroethylene(PTFE)fibers promote the potential application of hybrid PTFE/glass fabric composites in the tribological field,but their weak interfacial adhesion and inferior thermal properties significantly inhibit their tribological performance and reliability.Herein,a hybrid of polydopamine/silicon carbide/polyethyleneimine(PDA/SiC/PEI)functional coating was co‐deposited onto the hybrid PTFE/glass fabric surface through a one‐step impregnation method,leading to increased surface roughness and abundant amine groups.Tensile and peeling tests showed that this functional coating offered 47.8%enhancement in the fabric/matrix interfacial adhesion without compromising the strength of the pristine fabric.Moreover,the additional incorporation of WS_(2),and aluminum nitride(AlN)micro‐fillers contributed to the development of a high‐quality tribofilm and improved the thermal properties of fabric composites.The results of wear tests proved that the hybrid‐fabric composites,after the introduction of functional coating and micro‐fillers,exhibited outstanding tribological performance,which was attributed to the superior interfacial adhesion as well as the synergistic enhancement effects between WS2 and AlN micro‐fillers.

Fabrication of PTFE/Nomex fabric/phenolic composites using a layer-by-layer self-assembly method for tribology field application

Fabric composites are widely applied as self-lubricating liner for radial spherical plain bearings owing to their excellent mechanical and tribological properties.Nevertheless,the poor interfacial strength between fibers and the resin matrix limits the performance of composites utilized as tribomaterials.To overcome this drawback,a mild layer-by-layer(LbL)self-assembly method was successfully used to construct hybrid fabric composites in the present work.In addition,this investigation addressed the effect of self-assembly cycles on the friction and wear behaviors of hybrid fabric composites under dry sliding condition.The results demonstrate that fabric composites with three or more self-assembly cycles have significantly enhanced surface activities and anti-wear performances.The results obtained in this work can provide guidance in the preparation of self-lubricating liner composites and highlight how the LbL self-assembly techniques could influence the properties of hybrid fabric composites.

Optical identification of interlayer coupling of graphene/MoS_(2) van der Waals heterostructures

The interlayer coupling in van der Waals(vdW)heterostructures(vdWHs)is at the frontier of the fundamental research,underlying many optical behaviors.The graphene/MoS_(2) vdWHs provide an ideal platform to reveal the good interfacial coupling between graphene and MoS_(2) constituents.Here,three groups of graphene/MoS_(2) vdWHs were prepared by transferring 1–3 layers of graphene onto monolayer MoS_(2).The interlayer coupling within graphene/MoS_(2) vdWHs were characterized and analyzed by Raman spectroscopy,photoluminescence(PL)spectroscopy and optical contrast(OC)spectroscopy.The upshift of the A_(1g) peak of MoS_(2) and the upshift of the D and 2D peaks of SLG show that the electrons move from MoS_(2) to graphene accompanied by the dielectric shielding effect on graphene.The weakened PL intensities and the slight red shift of A peak prove that the electrons move from MoS_(2) to graphene meanwhile the recombination of hole and electron pairs is blocked in vdWHs.Our results deepen the understanding of the interlayer coupling of graphene/MoS_(2) vdWHs and therefore provide guidelines for the practical design and application of optoelectronic devices based on graphene/MoS_(2) vdWHs.

Surface modification of YS-20 with polydopamine for improving the tribological properties of polyimide composites

Recently,great effort has been devoted to prepare various reinforce fillers to improve polymer performances,but ignoring the importance of raw polymer powders which are indispensable parts of hot-pressed polymer composites.Herein,we engineer raw polyimide(PI)powders with the assistance of polydopamine(PDA)in aqueous solutions.After the modification,polymer powders change from hydrophobic to hydrophilic,which makes it is possible to further modification of polymer powders in liquid phase.During the curing process of modified polymer powders,the partial dehydration of the catechol groups and crosslinking of PDA via C–O–C bonds are confirmed.Based on the features of PDA,a non-destructive mixing method is utilized to realize homogeneous dispersion of multi-walled carbon nanotubes(MWCNTs)in polymer matrix.In comparison with ball milling method,this way can preserve the integrated innate structure of MWCNTs effectively.Besides,by taking full advantage of the reducing and metal-coordination capability of PDA,Cu2+is successfully loaded onto the surfaces of polymer powders.The related characterizations demonstrate that Cu2+in situ converts to metallic copper rather than copper oxide during the hot pressing process.The tribological properties of corresponding polymer composites are also studied.These results indicate that modifying polymer powders with PDA is multi-profit and presents practical application prospect.

A selective kernel-based cycle-consistent generative adversarial network for unpaired low-dose CT denoising

Low-dose computed tomography(LDCT)denoising is an indispensable procedure in the medical imaging field,which not only improves image quality,but can mitigate the potential hazard to patients caused by routine doses.Despite the improvement in performance of the cycle-consistent generative adversarial network(CycleGAN)due to the well-paired CT images shortage,there is still a need to further reduce image noise while retaining detailed features.Inspired by the residual encoder–decoder convolutional neural network(RED-CNN)and U-Net,we propose a novel unsupervised model using CycleGAN for LDCT imaging,which injects a two-sided network into selective kernel networks(SK-NET)to adaptively select features,and uses the patchGAN discriminator to generate CT images with more detail maintenance,aided by added perceptual loss.Based on patch-based training,the experimental results demonstrated that the proposed SKFCycleGAN outperforms competing methods in both a clinical dataset and the Mayo dataset.The main advantages of our method lie in noise suppression and edge preservation.