A lightweight flexible thermally stable composite is fabricated by com-bining silica nanofiber membranes(SNM)with MXene@c-MWCNT hybrid film.The flexible SNM with outstanding thermal insulation are prepared from tetrae...A lightweight flexible thermally stable composite is fabricated by com-bining silica nanofiber membranes(SNM)with MXene@c-MWCNT hybrid film.The flexible SNM with outstanding thermal insulation are prepared from tetraethyl orthosilicate hydrolysis and condensation by electrospinning and high-temperature calcination;the MXene@c-MWCNT_(x:y)films are prepared by vacuum filtration tech-nology.In particular,the SNM and MXene@c-MWCNT_(6:4)as one unit layer(SMC_(1))are bonded together with 5 wt%polyvinyl alcohol(PVA)solution,which exhibits low thermal conductivity(0.066 W m^(-1)K^(-1))and good electromagnetic interference(EMI)shielding performance(average EMI SE_(T),37.8 dB).With the increase in func-tional unit layer,the overall thermal insulation performance of the whole composite film(SMC_(x))remains stable,and EMI shielding performance is greatly improved,especially for SMC_(3)with three unit layers,the average EMI SET is as high as 55.4 dB.In addition,the organic combination of rigid SNM and tough MXene@c-MWCNT_(6:4)makes SMC_(x)exhibit good mechanical tensile strength.Importantly,SMC_(x)exhibit stable EMI shielding and excellent thermal insulation even in extreme heat and cold environment.Therefore,this work provides a novel design idea and important reference value for EMI shielding and thermal insulation components used in extreme environmental protection equipment in the future.展开更多
In this paper,we study the three-dimensional regularized MHD equations with fractional Laplacians in the dissipative and diffusive terms.We establish the global existence of mild solutions to this system with small in...In this paper,we study the three-dimensional regularized MHD equations with fractional Laplacians in the dissipative and diffusive terms.We establish the global existence of mild solutions to this system with small initial data.In addition,we also obtain the Gevrey class regularity and the temporal decay rate of the solution.展开更多
In order to ensure the operational reliability and infor-mation security of sophisticated electronic components and to protect human health,efficient electromagnetic interference(EMI)shielding materials are required t...In order to ensure the operational reliability and infor-mation security of sophisticated electronic components and to protect human health,efficient electromagnetic interference(EMI)shielding materials are required to attenuate electromagnetic wave energy.In this work,the cellulose solution is obtained by dissolving cotton through hydrogen bond driving self-assembly using sodium hydroxide(NaOH)/urea solution,and cellulose aerogels(CA)are prepared by gelation and freeze-drying.Then,the cellulose carbon aerogel@reduced graphene oxide aerogels(CCA@rGO)are prepared by vacuum impregnation,freeze-drying followed by thermal annealing,and finally,the CCA@rGO/polydimethylsiloxane(PDMS)EMI shielding composites are prepared by backfilling with PDMS.Owing to skin-core structure of CCA@rGO,the complete three-dimensional(3D)double-layer con-ductive network can be successfully constructed.When the loading of CCA@rGO is 3.05 wt%,CCA@rGO/PDMS EMI shielding composites have an excellent EMI shielding effectiveness(EMI SE)of 51 dB,which is 3.9 times higher than that of the co-blended CCA/rGO/PDMS EMI shielding composites(13 dB)with the same loading of fillers.At this time,the CCA@rGO/PDMS EMI shielding composites have excellent thermal stability(T_(HRI) of 178.3℃)and good thermal conductivity coefficient(λ of 0.65 W m^(-1) K^(-1)).Excellent comprehensive performance makes CCA@rGO/PDMS EMI shielding composites great prospect for applications in lightweight,flexible EMI shielding composites.展开更多
With the rapid development of fifth-generation mobile com-munication technology and wearable electronic devices,electromagnetic interference and radiation pollution caused by electromagnetic waves have attracted world...With the rapid development of fifth-generation mobile com-munication technology and wearable electronic devices,electromagnetic interference and radiation pollution caused by electromagnetic waves have attracted worldwide attention.Therefore,the design and development of highly efficient EMI shielding materials are of great importance.In this work,the three-dimensional graphene oxide(GO)with regular honeycomb structure(GH)is firstly constructed by sacrificial template and freeze-dry-ing methods.Then,the amino functionalized FeNi alloy particles(f-FeNi)are loaded on the GH skeleton followed by in-situ reduction to prepare rGH@FeNi aerogel.Finally,the rGH@FeNi/epoxy EMI shielding com-posites with regular honeycomb structure is obtained by vacuum-assisted impregnation of epoxy resin.Benefitting from the construction of regular honeycomb structure and electromagnetic synergistic effect,the rGH@FeNi/epoxy composites with a low rGH@FeNi mass fraction of 2.1 wt%(rGH and f-FeNi are 1.2 and 0.9 wt%,respectively)exhibit a high EMI shielding effectiveness(EMI SE)of 46 dB,which is 5.8 times of that(8 dB)for rGO/FeNi/epoxy composites with the same rGO/FeNi mass fraction.At the same time,the rGH@FeNi/epoxy composites also possess excellent thermal stability(heat-resistance index and temperature at the maximum decomposition rate are 179.1 and 389.0°C respectively)and mechanical properties(storage modulus is 8296.2 MPa).展开更多
With the widespread application of electronic communication technology,the resulting electromagnetic radiation pollution has been significantly increased.Metal matrix electromagnetic interference(EMI)shielding materia...With the widespread application of electronic communication technology,the resulting electromagnetic radiation pollution has been significantly increased.Metal matrix electromagnetic interference(EMI)shielding materials have disadvantages such as high density,easy corrosion,difficult processing and high price,etc.Polymer matrix EMI shielding composites possess light weight,corrosion resistance and easy processing.However,the current polymer matrix composites present relatively low electrical conductivity and poor EMI shielding performance.This review firstly discusses the key concept,loss mechanism and test method of EMI shielding.Then the current development status of EMI shielding materials is summarized,and the research progress of polymer matrix EMI shielding composites with different structures is illustrated,especially for their preparation methods and evaluation.Finally,the corresponding key scientific and technical problems are proposed,and their development trend is also prospected.展开更多
The development of lightweight and integration for electronics requires flexible films with high thermal conductivity and electromagnetic interference(EMI) shielding to overcome heat accumulation and electromagnetic r...The development of lightweight and integration for electronics requires flexible films with high thermal conductivity and electromagnetic interference(EMI) shielding to overcome heat accumulation and electromagnetic radiation pollution.Herein,the hierarchical design and assembly strategy was adopted to fabricate hierarchically multifunctional polyimide composite films,with graphene oxide/expanded graphite(GO/EG) as the top thermally conductive and EMI shielding layer,Fe_(3)O_(4)/polyimide(Fe_(3)O_(4)/PI) as the middle EMI shielding enhancement layer and electrospun PI fibers as the substrate layer for mechanical improvement.PI composite films with 61.0 wt% of GO/EG and 23.8 wt% of Fe_(3)O_(4)/PI exhibits high in-plane thermal conductivity coefficient(95.40 W(m K)^(-1)),excellent EMI shielding effectiveness(34.0 dB),good tensile strength(93.6 MPa) and fast electric-heating response(5 s).The test in the central processing unit verifies PI composite films present broad application prospects in electronics fields.展开更多
High-efficiency electromagnetic interference(EMI)shielding materials are of great importance for electronic equipment reliability,information security and human health.In this work,bidirectional aligned Ti_(3)C_(2)T_(...High-efficiency electromagnetic interference(EMI)shielding materials are of great importance for electronic equipment reliability,information security and human health.In this work,bidirectional aligned Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/CNF aerogels(BTFCA)were firstly assembled by bidirectional freezing and freeze-drying technique,and the BTFCA/epoxy nanocomposites with long-range aligned lamellar structures were then prepared by vacuum-assisted impregnation of epoxy resins.Benefitting from the successful construction of bidirectional aligned three-dimensional conductive networks and electromagnetic synergistic effect,when the mass fraction of Ti_(3)C_(2)T_(x) and Fe_(3)O_(4) are 2.96 and 1.48 wt%,BTFCA/epoxy nanocomposites show outstanding EMI shield-ing effectiveness of 79 dB,about 10 times of that of blended Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/epoxy(8 dB)nanocomposites with the same loadings of Ti_(3)C_(2)T_(x) and Fe_(3)O_(4).Meantime,the corresponding BTFCA/epoxy nanocomposites also present excellent thermal stability(T_(heat-resistance index) of 198.7℃)and mechanical properties(storage modulus of 9902.1 MPa,Young’s modulus of 4.51 GPa and hardness of 0.34 GPa).Our fabricated BTFCA/epoxy nanocomposites would greatly expand the applications of MXene and epoxy resins in the fields of information security,aerospace and weapon manufacturing,etc.展开更多
Electromagnetic interference(EMI)shielding materials with excellent flexibility and mechanical properties and outstanding thermal conductivity have become a hot topic of research in functional composites.In this study...Electromagnetic interference(EMI)shielding materials with excellent flexibility and mechanical properties and outstanding thermal conductivity have become a hot topic of research in functional composites.In this study,the“sol-gel-film conversion technique”is used to assemble polyetherimidefunctionalized Ti_(3)C_(2)T_(x) nanosheets(f-Ti_(3)C_(2)T_(x))with poly(p-phenylene-2,6-benzobisoxazole)(PBO)nanofibers(PNFs),followed by dialysis and vacuum drying to prepare f-Ti_(3)C_(2)T_(x)/PNF films with lamellar structures.When the loading of f-Ti_(3)C_(2)T_(x) is 70 wt%,the f-Ti_(3)C_(2)T_(x)/PNF film presents optimal comprehensive properties,with an EMI shielding effectiveness(SE)of 35 dB and a specific SE/thickness((SSE,SE/density)/t)of 8211 dB cm^(2)/g,a tensile strength of 125.1 MPa,an in-plane thermal conductivity coefficient(λ)of 5.82 W/(m K),and electrical conductivity of 1943 S/m.After repeated folding for 10,000 cycles,the EMI SE and the tensile strength of f-Ti_(3)C_(2)T_(x)/PNFs films still remain 33.4 dB and 116.1 MPa,respectively.Additionally,the f-Ti_(3)C_(2)T_(x)/PNF film also shows excellent thermal stability,flame retardancy,and structural stability.This would provide a novel method for the design and fabrication of multifunctional composite films and considerably expand the applications of MXene-and PNF-based composites in the fields of EMI shielding and thermal management.展开更多
BACKGROUND The safety and feasibility of the simultaneous resection of primary colorectal cancer (CRC) and synchronous colorectal liver metastases (SCRLM) have been demonstrated in some studies. Combined resection is ...BACKGROUND The safety and feasibility of the simultaneous resection of primary colorectal cancer (CRC) and synchronous colorectal liver metastases (SCRLM) have been demonstrated in some studies. Combined resection is expected to be the optimal strategy for patients with CRC and SCRLM. However, traditional laparotomy is traumatic, and the treatment outcome of minimally invasive surgery (MIS) is still obscure. AIM To compare the treatment outcomes of MIS and open surgery (OS) for the simultaneous resection of CRC and SCRLM. METHODS A systematic search through December 22, 2018 was conducted in electronic databases (PubMed, EMBASE, Web of Science, and Cochrane Library). All studies comparing the clinical outcomes of MIS and OS for patients with CRC and SCRLM were included by eligibility criteria. The meta-analysis was performed using Review Manager Software. The quality of the pooled study was assessed using the Newcastle-Ottawa scale. The publication bias was evaluated by a funnel plot and the Begg’s and Egger’s tests. Fixed- and random-effects models were applied according to heterogeneity. RESULTS Ten retrospective cohort studies involving 502 patients (216 patients in the MIS group and 286 patients in the OS group) were included in this study. MIS was associated with less intraoperative blood loss [weighted mean difference (WMD)=-130.09, 95% confidence interval (CI):-210.95 to -49.23, P = 0.002] and blood transfusion [odds ratio (OR)= 0.53, 95%CI: 0.29 to 0.95, P = 0.03], faster recovery of intestinal function (WMD =-0.88 d, 95%CI:-1.58 to -0.19, P = 0.01) and diet (WMD =-1.54 d, 95%CI:-2.30 to -0.78, P < 0.0001), shorter length of postoperative hospital stay (WMD =-4.06 d, 95%CI:-5.95 to -2.18, P < 0.0001), and lower rates of surgical complications (OR = 0.60, 95%CI: 0.37 to 0.99, P = 0.04). However, the operation time, rates and severity of overall complications, and rates of general complications showed no significant differences between the MIS and OS groups. Moreover, the overall survival and disease-free survival after MIS were equivalent to those after OS. CONCLUSION Considering the studies included in this meta-analysis, MIS is a safe and effective alternative technique for the simultaneous resection of CRC and SCRLM. Compared with OS, MIS has less intraoperative blood loss and blood transfusion and quicker postoperative recovery. Furthermore, the two groups show equivalent long-term outcomes.展开更多
Objective:To explore the regulation effect of Rheum palmatum(R.palmatum) L.on NF-κ.B signaling pathway of ALF mice.Methods:The intraperitoneal injection of D-GalN/LPS was employed for the model building.Mice in the t...Objective:To explore the regulation effect of Rheum palmatum(R.palmatum) L.on NF-κ.B signaling pathway of ALF mice.Methods:The intraperitoneal injection of D-GalN/LPS was employed for the model building.Mice in the treatment group and positive control group were given the R,palmatum L.and bifendate before the model building.Mice in the normal group were given the intraperitoneal injection of equivalent normal saline for continuously 3d.After 16 h of model building,the blood was collected from eyeballs of mice and then mice were executed.The measurement was performed on the content of ALT,AST,NO and 11-1βin the serum of mice in eaeh group,as well as the activity of Caspase 3 and Caspase 8 in the liver tissue.HE staining was employed to detect the pathological morphology of liver;and the western blot was used to detect the expression of iNOS,COX-2,Bax,Bcl-2,PCNA,NF-κ B p65 and I κ.B.Results:The content of ALT,AST,NO and I1-1β in the serum and the activity of Caspase 3 and Caspase 8 in the liver tissue were increased in the mice of ALF model group.Besides,the expression of iNOS,COX-2 and Bax was increased,the expression of Bcl-2 and PCNA was decreased,the phosphorylation of NF-κ B p65 and 1κ B was significant and the treatment group of R.palmatum L.could inhibit such change.Conclusions:Through NF-κB signaling pathway,the R.palmatum L.could reduce the content of enzyme of liver function and inflammation factor in the serum of ALF mice,regulate the expression of cell apoptosisrelated protein and improve the symptoms of ALF mice.展开更多
In this paper,we consider the 3D magnetic Bénard problem.More precisely,we prove that the large solutions are stable under certain conditions.And we obtain the equivalent condition with respect to this stability ...In this paper,we consider the 3D magnetic Bénard problem.More precisely,we prove that the large solutions are stable under certain conditions.And we obtain the equivalent condition with respect to this stability condition.Finally,we also establish the stability of 2 D magnetic Bénard problem under 3D perturbations.展开更多
Based on multiphase field conception and integrated with the idea of vector-valued phase field,a phase field model for typical allotropic transformation of solid solution is proposed.The model takes the non-uniform di...Based on multiphase field conception and integrated with the idea of vector-valued phase field,a phase field model for typical allotropic transformation of solid solution is proposed.The model takes the non-uniform distribution of grain boundaries of parent phase and crystal orientation into account in proper way,as being illustrated by the simulation of austenite to ferrite transformation in low carbon steel.It is found that the misorientation dependent grain boundary mobility shows strong influence on the formation of ferrite morphology comparing with the weak effect exerted by misorientation dependent grain boundary energy.The evolution of various types of grain boundaries are quantitatively characterized in terms of its respective grain boundary energy dissipation.The simulated ferrite fraction agrees well with the expectation from phase diagram,which verifies this model.展开更多
[Objectives]This study aimed to evaluate the quality of Bupleurum falcatum Linne interplanted with walnut in Ganluo and study the development and utilization value of other parts.[Methods]The contents of saikosaponins...[Objectives]This study aimed to evaluate the quality of Bupleurum falcatum Linne interplanted with walnut in Ganluo and study the development and utilization value of other parts.[Methods]The contents of saikosaponins a and d were determined with RP-HPLC,and the contents of 7 kinds of harmful elements were determined by ICP-MS.The quality of B.falcatum Linne was compared with that of other Bupleurum species.[Results]The total saikosaponin content in Radix Bupleurum Falcatum(15.894 mg/g)was higher than that in Radix Bupleuri of other origins(8.748 mg/g).The total saikosaponin content in leaves of B.falcatum Linne(7.518 mg/g)is more than twice the limit promulgated by Chinese Pharmacopoeia.The contents of Al,Cr,Cu,As,Cd,Pb and Hg in B.falcatum Linne were all lower than the limits promulgated by the pharmacopoeia.In short,the quality of Radix Bupleurum Falcatum was better than that of Radix Bupleurum Marginatum(S3,S4)and Radix Bupleurum Sachalinense(S5).The leaves of B.falcatum Linne contained more saikosaponins and less harmful elements.[Conclusions]The method and technology of interplanting B.falcatum Linne with walnut in Ganluo are mature.The quality of the medicinal materials produced is superior,and the leaves are also rich in saikosaponins a and d,and can be used as the raw material for extracting saikosaponins a and d.This study provides a basis for further in-depth research on the cultivation of B.falcatum Linne in the domestic market.展开更多
Evodiamine is an indole quinazoline alkaloid with anti-tumor activity,which may be developed into a drug for the treatment of tumor.It was found that evodiamine could inhibit or even block the signal pathways of Wnt/...Evodiamine is an indole quinazoline alkaloid with anti-tumor activity,which may be developed into a drug for the treatment of tumor.It was found that evodiamine could inhibit or even block the signal pathways of Wnt/β-catenin,mTOR,NF--κB,PI3K/AKT,Hippo-YAP and BMP in many kinds of cancer cells,thus interfering with cell division and differentiation,increasing the rate of apoptosis,and down-regulating the expression of various cancer cell markers.Such as B-cell lymphoma 2(Bcl-2),B-cell lymphoma super-large(Bcl-XL),cyclooxygenase 2(COX-2),Survivin,vascular endothelial growth factor(VEGF)and matrix metallopeptidase 9(MMP-9),which have a strong inhibitory effect on asymmetric division,malignant proliferation and angiogenesis of tumor cells.This paper summarizes evodiamine in digestive system tumors by regulating Wnt/β-catenin,mTOR,PI3K/AKT,BMP and other signal pathways,interfering with cell division,differentiation and apoptosis,inhibiting the expression of tumor-related marker genes,and preventing tumor cell migration and invasion,so as to provide a basis for the clinical application and further research of evodiamine in the future.展开更多
In order to apply the LM device previously developed to precisely measuring small motion trajectories located on the different motion planes, three major improvements are successfully performed under the condition of ...In order to apply the LM device previously developed to precisely measuring small motion trajectories located on the different motion planes, three major improvements are successfully performed under the condition of completely maintaining the advantages of the device. These improvements include 1) development of a novel connection mechanism to smoothly attach the device to the spindle of a machining centre;2) employment of a new data sampling method to achieve a high sampling frequency independent of the operating system of the control computer;and 3) proposal of a set-up method to conveniently install the device on the test machining centre with respect to different motion planes. Practical measurement experiment results with the improved device on a machining centre sufficiently demonstrate the effectiveness of the improvements and confirm several features including a very good response to small displacement close to the resolution of the device, high precision, repeatability and reliance. Moreover, based on the measurement results for a number of trajectories for a wide range of motion conditions, the error characteristics of small size motions are systematically discussed and the effect of the movement size and feed rate on the motion accuracy is verified for the machining centre tested.展开更多
High-temperature carbonized metal-organic frameworks(MOFs)derivatives have demonstrated their superiority for promising electromagnetic wave(EMW)absorbers,but they still suffer from limited EMW absorption capacity and...High-temperature carbonized metal-organic frameworks(MOFs)derivatives have demonstrated their superiority for promising electromagnetic wave(EMW)absorbers,but they still suffer from limited EMW absorption capacity and narrow bandwidth.Considering the advantage of microstructure and chemical composition regulation for the design of EMW absorber,hierarchical heterostructured MoS_(2)/CoS_(2)-Co_(3)O_(4)@cabonized cotton fabric(CF)(MCC@CCF)is prepared by growing ZIF-67 MOFs onto CF surface,chemical etching,and carbonization.Aside from the dual loss mechanism of magnetic-dielectric multicomponent carbonized MOFs,chemical etching and carbonization process can effectively introduce abundant micro-gap structure that can result in better impedance matching and stronger absorption capacity via internal reflection,doped heteroatoms(Mo,N,S)to supply additional dipolar polarization loss,and numerous heterointerfaces among MoS_(2),CoS_(2),Co_(3)O_(4),and CCF that produce promoted conduction loss and interfacial polarization loss.Thus,a minimal reflection loss of−52.87 dB and a broadest effective absorption bandwidth of 6.88 GHz were achieved via tunning the sample thickness and filler loading,showing excellent EMW absorption performances.This research is of great value for guiding the research on MOFs derivatives based EMW absorbing materials.展开更多
基金the China Scholarship Council(2021)the Deanship of Scientific Research at Northern Border University,Arar,KSA for funding this research work through the project number“NBU-FPEJ-2024-249-03”.
文摘A lightweight flexible thermally stable composite is fabricated by com-bining silica nanofiber membranes(SNM)with MXene@c-MWCNT hybrid film.The flexible SNM with outstanding thermal insulation are prepared from tetraethyl orthosilicate hydrolysis and condensation by electrospinning and high-temperature calcination;the MXene@c-MWCNT_(x:y)films are prepared by vacuum filtration tech-nology.In particular,the SNM and MXene@c-MWCNT_(6:4)as one unit layer(SMC_(1))are bonded together with 5 wt%polyvinyl alcohol(PVA)solution,which exhibits low thermal conductivity(0.066 W m^(-1)K^(-1))and good electromagnetic interference(EMI)shielding performance(average EMI SE_(T),37.8 dB).With the increase in func-tional unit layer,the overall thermal insulation performance of the whole composite film(SMC_(x))remains stable,and EMI shielding performance is greatly improved,especially for SMC_(3)with three unit layers,the average EMI SET is as high as 55.4 dB.In addition,the organic combination of rigid SNM and tough MXene@c-MWCNT_(6:4)makes SMC_(x)exhibit good mechanical tensile strength.Importantly,SMC_(x)exhibit stable EMI shielding and excellent thermal insulation even in extreme heat and cold environment.Therefore,this work provides a novel design idea and important reference value for EMI shielding and thermal insulation components used in extreme environmental protection equipment in the future.
基金supported by the Opening Project of Guangdong Province Key Laboratory of Cyber-Physical System(20168030301008)supported by the National Natural Science Foundation of China(11126266)+4 种基金the Natural Science Foundation of Guangdong Province(2016A030313390)the Quality Engineering Project of Guangdong Province(SCAU-2021-69)the SCAU Fund for High-level University Buildingsupported by the National Key Research and Development Program of China(2020YFA0712500)the National Natural Science Foundation of China(11971496,12126609)。
文摘In this paper,we study the three-dimensional regularized MHD equations with fractional Laplacians in the dissipative and diffusive terms.We establish the global existence of mild solutions to this system with small initial data.In addition,we also obtain the Gevrey class regularity and the temporal decay rate of the solution.
基金the Foundation of National Natural Science Foundation of China(51773169 and 51973173)the Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China(2019JC-11)+2 种基金the Natural Science Basic Research Plan in Shaanxi Province of China(2020JQ-164)Y.Q.Guo thanks the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX202055)Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘In order to ensure the operational reliability and infor-mation security of sophisticated electronic components and to protect human health,efficient electromagnetic interference(EMI)shielding materials are required to attenuate electromagnetic wave energy.In this work,the cellulose solution is obtained by dissolving cotton through hydrogen bond driving self-assembly using sodium hydroxide(NaOH)/urea solution,and cellulose aerogels(CA)are prepared by gelation and freeze-drying.Then,the cellulose carbon aerogel@reduced graphene oxide aerogels(CCA@rGO)are prepared by vacuum impregnation,freeze-drying followed by thermal annealing,and finally,the CCA@rGO/polydimethylsiloxane(PDMS)EMI shielding composites are prepared by backfilling with PDMS.Owing to skin-core structure of CCA@rGO,the complete three-dimensional(3D)double-layer con-ductive network can be successfully constructed.When the loading of CCA@rGO is 3.05 wt%,CCA@rGO/PDMS EMI shielding composites have an excellent EMI shielding effectiveness(EMI SE)of 51 dB,which is 3.9 times higher than that of the co-blended CCA/rGO/PDMS EMI shielding composites(13 dB)with the same loading of fillers.At this time,the CCA@rGO/PDMS EMI shielding composites have excellent thermal stability(T_(HRI) of 178.3℃)and good thermal conductivity coefficient(λ of 0.65 W m^(-1) K^(-1)).Excellent comprehensive performance makes CCA@rGO/PDMS EMI shielding composites great prospect for applications in lightweight,flexible EMI shielding composites.
基金supports from the National Natural Science Foundation of China(U21A2093 and 51903145)Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China(2019JC-11)and Fundamental Research Funds for the Central Universities(D5000210627)This work is also financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘With the rapid development of fifth-generation mobile com-munication technology and wearable electronic devices,electromagnetic interference and radiation pollution caused by electromagnetic waves have attracted worldwide attention.Therefore,the design and development of highly efficient EMI shielding materials are of great importance.In this work,the three-dimensional graphene oxide(GO)with regular honeycomb structure(GH)is firstly constructed by sacrificial template and freeze-dry-ing methods.Then,the amino functionalized FeNi alloy particles(f-FeNi)are loaded on the GH skeleton followed by in-situ reduction to prepare rGH@FeNi aerogel.Finally,the rGH@FeNi/epoxy EMI shielding com-posites with regular honeycomb structure is obtained by vacuum-assisted impregnation of epoxy resin.Benefitting from the construction of regular honeycomb structure and electromagnetic synergistic effect,the rGH@FeNi/epoxy composites with a low rGH@FeNi mass fraction of 2.1 wt%(rGH and f-FeNi are 1.2 and 0.9 wt%,respectively)exhibit a high EMI shielding effectiveness(EMI SE)of 46 dB,which is 5.8 times of that(8 dB)for rGO/FeNi/epoxy composites with the same rGO/FeNi mass fraction.At the same time,the rGH@FeNi/epoxy composites also possess excellent thermal stability(heat-resistance index and temperature at the maximum decomposition rate are 179.1 and 389.0°C respectively)and mechanical properties(storage modulus is 8296.2 MPa).
基金The authors are grateful for the support and funding from the Foundation of National Natural Science Foundation of China(51903145 and 51973173)Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China(2019JC-11)+1 种基金Fundamental Research Funds for the Central Universities(D5000210627)This work is also financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘With the widespread application of electronic communication technology,the resulting electromagnetic radiation pollution has been significantly increased.Metal matrix electromagnetic interference(EMI)shielding materials have disadvantages such as high density,easy corrosion,difficult processing and high price,etc.Polymer matrix EMI shielding composites possess light weight,corrosion resistance and easy processing.However,the current polymer matrix composites present relatively low electrical conductivity and poor EMI shielding performance.This review firstly discusses the key concept,loss mechanism and test method of EMI shielding.Then the current development status of EMI shielding materials is summarized,and the research progress of polymer matrix EMI shielding composites with different structures is illustrated,especially for their preparation methods and evaluation.Finally,the corresponding key scientific and technical problems are proposed,and their development trend is also prospected.
基金the support and funding from National Natural Science Foundation of China(51773169 and 51973173)Technical Basis Scientific Research Project(Highly Thermally Conductive Nonmetal Materials)+3 种基金Guangdong Basic and Applied Basic Research Foundation(2019B1515120093)Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China(2019JC-11)Y.Q.Guo thanks for the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX202055)This work is also financially supported by Polymer Electromagnetic Functional Materials Innovation Team of Shaanxi Sanqin Scholars.
文摘The development of lightweight and integration for electronics requires flexible films with high thermal conductivity and electromagnetic interference(EMI) shielding to overcome heat accumulation and electromagnetic radiation pollution.Herein,the hierarchical design and assembly strategy was adopted to fabricate hierarchically multifunctional polyimide composite films,with graphene oxide/expanded graphite(GO/EG) as the top thermally conductive and EMI shielding layer,Fe_(3)O_(4)/polyimide(Fe_(3)O_(4)/PI) as the middle EMI shielding enhancement layer and electrospun PI fibers as the substrate layer for mechanical improvement.PI composite films with 61.0 wt% of GO/EG and 23.8 wt% of Fe_(3)O_(4)/PI exhibits high in-plane thermal conductivity coefficient(95.40 W(m K)^(-1)),excellent EMI shielding effectiveness(34.0 dB),good tensile strength(93.6 MPa) and fast electric-heating response(5 s).The test in the central processing unit verifies PI composite films present broad application prospects in electronics fields.
基金The authors are grateful for the supports from the National Natural Science Foundation of China(U21A2093 and 52203100)Y.L.Zhang would like to thank the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX2021107)。
文摘High-efficiency electromagnetic interference(EMI)shielding materials are of great importance for electronic equipment reliability,information security and human health.In this work,bidirectional aligned Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/CNF aerogels(BTFCA)were firstly assembled by bidirectional freezing and freeze-drying technique,and the BTFCA/epoxy nanocomposites with long-range aligned lamellar structures were then prepared by vacuum-assisted impregnation of epoxy resins.Benefitting from the successful construction of bidirectional aligned three-dimensional conductive networks and electromagnetic synergistic effect,when the mass fraction of Ti_(3)C_(2)T_(x) and Fe_(3)O_(4) are 2.96 and 1.48 wt%,BTFCA/epoxy nanocomposites show outstanding EMI shield-ing effectiveness of 79 dB,about 10 times of that of blended Ti_(3)C_(2)T_(x)@Fe_(3)O_(4)/epoxy(8 dB)nanocomposites with the same loadings of Ti_(3)C_(2)T_(x) and Fe_(3)O_(4).Meantime,the corresponding BTFCA/epoxy nanocomposites also present excellent thermal stability(T_(heat-resistance index) of 198.7℃)and mechanical properties(storage modulus of 9902.1 MPa,Young’s modulus of 4.51 GPa and hardness of 0.34 GPa).Our fabricated BTFCA/epoxy nanocomposites would greatly expand the applications of MXene and epoxy resins in the fields of information security,aerospace and weapon manufacturing,etc.
基金The authors are grateful for the support of and funding from the Foundation of National Natural Science Foundation of China(51903145 and 51973173)the Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China(2019JC-11)+1 种基金Fundamental Research Funds for the Central Universities(D5000210627)L.Wang is grateful to the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(CX202053).
文摘Electromagnetic interference(EMI)shielding materials with excellent flexibility and mechanical properties and outstanding thermal conductivity have become a hot topic of research in functional composites.In this study,the“sol-gel-film conversion technique”is used to assemble polyetherimidefunctionalized Ti_(3)C_(2)T_(x) nanosheets(f-Ti_(3)C_(2)T_(x))with poly(p-phenylene-2,6-benzobisoxazole)(PBO)nanofibers(PNFs),followed by dialysis and vacuum drying to prepare f-Ti_(3)C_(2)T_(x)/PNF films with lamellar structures.When the loading of f-Ti_(3)C_(2)T_(x) is 70 wt%,the f-Ti_(3)C_(2)T_(x)/PNF film presents optimal comprehensive properties,with an EMI shielding effectiveness(SE)of 35 dB and a specific SE/thickness((SSE,SE/density)/t)of 8211 dB cm^(2)/g,a tensile strength of 125.1 MPa,an in-plane thermal conductivity coefficient(λ)of 5.82 W/(m K),and electrical conductivity of 1943 S/m.After repeated folding for 10,000 cycles,the EMI SE and the tensile strength of f-Ti_(3)C_(2)T_(x)/PNFs films still remain 33.4 dB and 116.1 MPa,respectively.Additionally,the f-Ti_(3)C_(2)T_(x)/PNF film also shows excellent thermal stability,flame retardancy,and structural stability.This would provide a novel method for the design and fabrication of multifunctional composite films and considerably expand the applications of MXene-and PNF-based composites in the fields of EMI shielding and thermal management.
基金the National Natural Science Foundation of China,No.81660487
文摘BACKGROUND The safety and feasibility of the simultaneous resection of primary colorectal cancer (CRC) and synchronous colorectal liver metastases (SCRLM) have been demonstrated in some studies. Combined resection is expected to be the optimal strategy for patients with CRC and SCRLM. However, traditional laparotomy is traumatic, and the treatment outcome of minimally invasive surgery (MIS) is still obscure. AIM To compare the treatment outcomes of MIS and open surgery (OS) for the simultaneous resection of CRC and SCRLM. METHODS A systematic search through December 22, 2018 was conducted in electronic databases (PubMed, EMBASE, Web of Science, and Cochrane Library). All studies comparing the clinical outcomes of MIS and OS for patients with CRC and SCRLM were included by eligibility criteria. The meta-analysis was performed using Review Manager Software. The quality of the pooled study was assessed using the Newcastle-Ottawa scale. The publication bias was evaluated by a funnel plot and the Begg’s and Egger’s tests. Fixed- and random-effects models were applied according to heterogeneity. RESULTS Ten retrospective cohort studies involving 502 patients (216 patients in the MIS group and 286 patients in the OS group) were included in this study. MIS was associated with less intraoperative blood loss [weighted mean difference (WMD)=-130.09, 95% confidence interval (CI):-210.95 to -49.23, P = 0.002] and blood transfusion [odds ratio (OR)= 0.53, 95%CI: 0.29 to 0.95, P = 0.03], faster recovery of intestinal function (WMD =-0.88 d, 95%CI:-1.58 to -0.19, P = 0.01) and diet (WMD =-1.54 d, 95%CI:-2.30 to -0.78, P < 0.0001), shorter length of postoperative hospital stay (WMD =-4.06 d, 95%CI:-5.95 to -2.18, P < 0.0001), and lower rates of surgical complications (OR = 0.60, 95%CI: 0.37 to 0.99, P = 0.04). However, the operation time, rates and severity of overall complications, and rates of general complications showed no significant differences between the MIS and OS groups. Moreover, the overall survival and disease-free survival after MIS were equivalent to those after OS. CONCLUSION Considering the studies included in this meta-analysis, MIS is a safe and effective alternative technique for the simultaneous resection of CRC and SCRLM. Compared with OS, MIS has less intraoperative blood loss and blood transfusion and quicker postoperative recovery. Furthermore, the two groups show equivalent long-term outcomes.
基金supported by National Natural Science Foundation of China(81460718)Research Topic of Guangxi University of Chinese Medicine(YB14007)
文摘Objective:To explore the regulation effect of Rheum palmatum(R.palmatum) L.on NF-κ.B signaling pathway of ALF mice.Methods:The intraperitoneal injection of D-GalN/LPS was employed for the model building.Mice in the treatment group and positive control group were given the R,palmatum L.and bifendate before the model building.Mice in the normal group were given the intraperitoneal injection of equivalent normal saline for continuously 3d.After 16 h of model building,the blood was collected from eyeballs of mice and then mice were executed.The measurement was performed on the content of ALT,AST,NO and 11-1βin the serum of mice in eaeh group,as well as the activity of Caspase 3 and Caspase 8 in the liver tissue.HE staining was employed to detect the pathological morphology of liver;and the western blot was used to detect the expression of iNOS,COX-2,Bax,Bcl-2,PCNA,NF-κ B p65 and I κ.B.Results:The content of ALT,AST,NO and I1-1β in the serum and the activity of Caspase 3 and Caspase 8 in the liver tissue were increased in the mice of ALF model group.Besides,the expression of iNOS,COX-2 and Bax was increased,the expression of Bcl-2 and PCNA was decreased,the phosphorylation of NF-κ B p65 and 1κ B was significant and the treatment group of R.palmatum L.could inhibit such change.Conclusions:Through NF-κB signaling pathway,the R.palmatum L.could reduce the content of enzyme of liver function and inflammation factor in the serum of ALF mice,regulate the expression of cell apoptosisrelated protein and improve the symptoms of ALF mice.
基金supported partially by NSFC(11571380,11971497,11871230)Natural Science Foundation of GuangDong Province(2019B151502041)+3 种基金supported partially by NSFC(11126266)Natural Science Foundation of GuangDong Province(2016A030313390)SCAU Fund for High-level University Buildingsupported partially by NSFC(11971496)。
文摘In this paper,we consider the 3D magnetic Bénard problem.More precisely,we prove that the large solutions are stable under certain conditions.And we obtain the equivalent condition with respect to this stability condition.Finally,we also establish the stability of 2 D magnetic Bénard problem under 3D perturbations.
基金The work was supported by the fund of the State Key Laboratory of Solidification Processing in NWPU(Grant No.SKLSP201725).
文摘Based on multiphase field conception and integrated with the idea of vector-valued phase field,a phase field model for typical allotropic transformation of solid solution is proposed.The model takes the non-uniform distribution of grain boundaries of parent phase and crystal orientation into account in proper way,as being illustrated by the simulation of austenite to ferrite transformation in low carbon steel.It is found that the misorientation dependent grain boundary mobility shows strong influence on the formation of ferrite morphology comparing with the weak effect exerted by misorientation dependent grain boundary energy.The evolution of various types of grain boundaries are quantitatively characterized in terms of its respective grain boundary energy dissipation.The simulated ferrite fraction agrees well with the expectation from phase diagram,which verifies this model.
基金Science and Technology Plan Project of Sichuan Province(2018NZ0113)Technology Research and Development and Promotion and Application Project of Liangshan Prefecture(17YYJS0084)Fundamental Research Funds for the Central Universities(2018NQN13).
文摘[Objectives]This study aimed to evaluate the quality of Bupleurum falcatum Linne interplanted with walnut in Ganluo and study the development and utilization value of other parts.[Methods]The contents of saikosaponins a and d were determined with RP-HPLC,and the contents of 7 kinds of harmful elements were determined by ICP-MS.The quality of B.falcatum Linne was compared with that of other Bupleurum species.[Results]The total saikosaponin content in Radix Bupleurum Falcatum(15.894 mg/g)was higher than that in Radix Bupleuri of other origins(8.748 mg/g).The total saikosaponin content in leaves of B.falcatum Linne(7.518 mg/g)is more than twice the limit promulgated by Chinese Pharmacopoeia.The contents of Al,Cr,Cu,As,Cd,Pb and Hg in B.falcatum Linne were all lower than the limits promulgated by the pharmacopoeia.In short,the quality of Radix Bupleurum Falcatum was better than that of Radix Bupleurum Marginatum(S3,S4)and Radix Bupleurum Sachalinense(S5).The leaves of B.falcatum Linne contained more saikosaponins and less harmful elements.[Conclusions]The method and technology of interplanting B.falcatum Linne with walnut in Ganluo are mature.The quality of the medicinal materials produced is superior,and the leaves are also rich in saikosaponins a and d,and can be used as the raw material for extracting saikosaponins a and d.This study provides a basis for further in-depth research on the cultivation of B.falcatum Linne in the domestic market.
基金National Natural Science Foundation of China(No.81660827)Huang Guihua inheritance Studio Construction Project of famous traditional Chinese Medicine of Guangxi University of traditional Chinese Medicine(No.[2017]2)。
文摘Evodiamine is an indole quinazoline alkaloid with anti-tumor activity,which may be developed into a drug for the treatment of tumor.It was found that evodiamine could inhibit or even block the signal pathways of Wnt/β-catenin,mTOR,NF--κB,PI3K/AKT,Hippo-YAP and BMP in many kinds of cancer cells,thus interfering with cell division and differentiation,increasing the rate of apoptosis,and down-regulating the expression of various cancer cell markers.Such as B-cell lymphoma 2(Bcl-2),B-cell lymphoma super-large(Bcl-XL),cyclooxygenase 2(COX-2),Survivin,vascular endothelial growth factor(VEGF)and matrix metallopeptidase 9(MMP-9),which have a strong inhibitory effect on asymmetric division,malignant proliferation and angiogenesis of tumor cells.This paper summarizes evodiamine in digestive system tumors by regulating Wnt/β-catenin,mTOR,PI3K/AKT,BMP and other signal pathways,interfering with cell division,differentiation and apoptosis,inhibiting the expression of tumor-related marker genes,and preventing tumor cell migration and invasion,so as to provide a basis for the clinical application and further research of evodiamine in the future.
文摘In order to apply the LM device previously developed to precisely measuring small motion trajectories located on the different motion planes, three major improvements are successfully performed under the condition of completely maintaining the advantages of the device. These improvements include 1) development of a novel connection mechanism to smoothly attach the device to the spindle of a machining centre;2) employment of a new data sampling method to achieve a high sampling frequency independent of the operating system of the control computer;and 3) proposal of a set-up method to conveniently install the device on the test machining centre with respect to different motion planes. Practical measurement experiment results with the improved device on a machining centre sufficiently demonstrate the effectiveness of the improvements and confirm several features including a very good response to small displacement close to the resolution of the device, high precision, repeatability and reliance. Moreover, based on the measurement results for a number of trajectories for a wide range of motion conditions, the error characteristics of small size motions are systematically discussed and the effect of the movement size and feed rate on the motion accuracy is verified for the machining centre tested.
基金supported by the National Natural Science Foundation of China(Nos.52373093 and 12072325)Outstanding Youth Fund of Henan Province(No.242300421062)+2 种基金the National Key R&D Program of China(No.2019YFA0706802)the 111 project(No.D18023)The authors also extend their appreciation to the Deanship of Scientific Research at Northern Border University,Arar,KSA for funding this research“work through the project number‘NBU-FFR-2024-540-03’”.
文摘High-temperature carbonized metal-organic frameworks(MOFs)derivatives have demonstrated their superiority for promising electromagnetic wave(EMW)absorbers,but they still suffer from limited EMW absorption capacity and narrow bandwidth.Considering the advantage of microstructure and chemical composition regulation for the design of EMW absorber,hierarchical heterostructured MoS_(2)/CoS_(2)-Co_(3)O_(4)@cabonized cotton fabric(CF)(MCC@CCF)is prepared by growing ZIF-67 MOFs onto CF surface,chemical etching,and carbonization.Aside from the dual loss mechanism of magnetic-dielectric multicomponent carbonized MOFs,chemical etching and carbonization process can effectively introduce abundant micro-gap structure that can result in better impedance matching and stronger absorption capacity via internal reflection,doped heteroatoms(Mo,N,S)to supply additional dipolar polarization loss,and numerous heterointerfaces among MoS_(2),CoS_(2),Co_(3)O_(4),and CCF that produce promoted conduction loss and interfacial polarization loss.Thus,a minimal reflection loss of−52.87 dB and a broadest effective absorption bandwidth of 6.88 GHz were achieved via tunning the sample thickness and filler loading,showing excellent EMW absorption performances.This research is of great value for guiding the research on MOFs derivatives based EMW absorbing materials.