Photobiomodulation inhibits the expression of chondroitin sulfate proteoglycans after spinal cord injury via the Sox9 pathway

Both glial cells and glia scar greatly affect the development of spinal cord injury and have become hot spots in research on spinal cord injury treatment.The cellular deposition of dense extracellular matrix proteins such as chondroitin sulfate proteoglycans inside and around the glial scar is known to affect axonal growth and be a major obstacle to autogenous repair.These proteins are thus candidate targets for spinal cord injury therapy.Our previous studies demonstrated that 810 nm photo biomodulation inhibited the formation of chondroitin sulfate proteoglycans after spinal cord injury and greatly improved motor function in model animals.However,the specific mechanism and potential targets involved remain to be clarified.In this study,to investigate the therapeutic effect of photo biomodulation,we established a mouse model of spinal cord injury by T9 clamping and irradiated the injury site at a power density of 50 mW/cm~2 for 50 minutes once a day for 7 consecutive days.We found that photobiomodulation greatly restored motor function in mice and down regulated chondroitin sulfate proteoglycan expression in the injured spinal cord.Bioinformatics analysis revealed that photobiomodulation inhibited the expression of proteoglycan-related genes induced by spinal cord injury,and versican,a type of proteoglycan,was one of the most markedly changed molecules.Immunofluorescence staining showed that after spinal cord injury,versican was present in astrocytes in spinal cord tissue.The expression of versican in primary astrocytes cultured in vitro increased after inflammation induction,whereas photobiomodulation inhibited the expression of ve rsican.Furthermore,we found that the increased levels of p-Smad3,p-P38 and p-Erk in inflammatory astrocytes were reduced after photobiomodulation treatment and after delivery of inhibitors including FR 180204,(E)-SIS3,and SB 202190.This suggests that Sma d 3/Sox9 and MAP K/Sox9 pathways may be involved in the effects of photobiomodulation.In summary,our findings show that photobiomodulation modulates the expression of chondroitin sulfate proteoglycans,and versican is one of the key target molecules of photo biomodulation.MAPK/Sox9 and Smad3/Sox9 pathways may play a role in the effects of photo biomodulation on chondroitin sulfate proteoglycan accumulation after spinal cord injury.

超薄2D/2D NiPS_(3)/C_(3)N_(5)异质结的界面工程促进光催化产氢

探索高效水分解光催化剂具有获得氢能源的巨大潜力。调控异质结界面可以有效地促进电荷载流子的分离和太阳能的利用,从而提高光催化活性。本工作使用了一种机械混合辅助自组装方法来构建NiPS_(3)(NPS)纳米片(NSs)/C_(3)N_(5)(CN) NSs (NPS/CN)异质结,即在二维(2D) CN NSs表面紧密沉积2D NPS NSs以形成2D/2D异质结构。在可见光下,通过在去离子水和海水中分解水生成氢气来评价样品的光催化性能。与CNNSs和NPSNSs相比,NPS/CN复合材料显示出较高的光催化产氢(PHE)活性,这是由于光捕获能力增加和异质结形成的协同作用所致。然而,过量的NPS NSs沉积在CNNSs表面会降低NPS/CN中CNNSs组分的光吸收,从而降低NPS/CN复合材料的PHE活性。这表明,NPS/CN复合材料要获得良好的光催化活性,需要两个组分之间适当的质量比。优化后的光催化剂(3-NPS/CN)具有良好的结构稳定性,在可见光下PHE效率最高,为47.71 μmol·h^(-1),是CN NSs的2385.50倍。此外,3-NPS/CN在海水中也表现出良好的PHE活性,反应速率为8.99 μmol·h^(-1)。采用光电化学、稳态光致发光(PL)、时间分辨光致发光(TR-PL)、稳态表面光电压(SPV)和时间分辨表面光电压(TPV)技术研究了不同光催化剂上的电荷分离和迁移。根据表征结果提出了一种可能的PHE机理。在NPS/CN光催化剂中,由于CN NSs和NPS NSs之间的电位差和强的界面电子耦合,光生电子从CN NSs的导带迅速迁移到NPS NSs的导带。然后,聚积在NPS NSs组份导带上的光生电子可以有效地还原质子生成氢气分子。同时,在三乙醇胺(TEOA)分子存在下,CN NSs和NPS NSs的价带上的光生空穴被消耗。本研究提供了一种简单的2D/2D异质结构光催化剂制备方法,该方法对于构建高效二维异质结光催化剂在能源领域中的应用具有重要价值。

Veratrilla baillonii Franch alleviate the symptoms of diabetes in type 2 diabetic rats induced by high-fat diet and streptozotocin

Our previous research studies have shown that Veratrilla baillonii Franch,a food supplement used by ethnic minorities in Southwest China,has multiple pharmacological activities,such as detoxification,antiinflammatory,antioxidant,and anti-insulin resistance.However,the detailed signal pathways for its salutary effect on damages in multiple organs due to type 2 diabetes mellitus(T2DM)remains unclear.The current study is to evaluate the therapeutic effects of V.baillonii on T2DM rats and to explore the underlying mechanisms.The T2DM rat model was successfully established by a high-sugar and high-fat diet(HFD)combination with intraperitoneal injection of a small dose of streptozotocin(STZ,35 mg/kg).Biochemical analysis and histopatholgical examinations were conducted to evaluate the anti-diabetic potential of water extracts of V.baillonii(WVBF).The results showed that the WVBF treatment can improve hyperglycemia and insulin resistance,ameliorate the liver,kidney and pancreas injuries via decreasing inflammatory cytokines such as IL-6 and TNF-α,and oxidative damages.Further investigation suggested that WVBF modulates the signal transductions of the IRS1/PI3K/AKT/GLUT4 and AMPK pathways.These findings demonstrate potentials of WVBF in the treatment of T2DM and possible mechanisms for its hepatoprotective activities.

Linking 24-h Movement Behavior Guidelines to Cognitive Difficulties,Internalizing and Externalizing Problems in Preterm Youth

Background:Given the heightened risk of developmental challenges associated with preterm birth,it is crucial to explore interventions that may ameliorate potential adverse outcomes.This study aimed to examine whether meeting the 24-h movement behavior(24-HMB)guidelines,which include recommendations on physical activity(PA),screen time(ST),and sleep(SL),is related to indicators of cognitive difficulties,internalizing problems(e.g.,depression and anxiety),and externalizing problems(e.g.,difficulties in making friends and arguing)in a sample of preterm youth(children and adolescents born preterm).Methods:In this cross-sectional study,data from 3410 preterm youth(aged 6 to 17 years)were included for data analyses.Multivariable logistic regression was used to investigate associations between meeting the 24-HMB guidelines and the above-mentioned health outcomes,while controlling for sociodemographic and health-related factors.Results:The prevalence of meeting 24-HMB guidelines varied across independent and integrated components of the 24-HMB guidelines.Meeting the ST guideline alone(p<0.05)and integrated guidelines(i.e.,ST+SL and ST+SL+PA)were associated with fewer cognitive difficulties and reduced internalizing and externalizing problems(p<0.05).Specifically,meeting the SL guideline alone and integrated guidelines(i.e.,SL+ST)were associated with lower odds of depression and anxiety(p<0.01).Additionally,meeting independent,and integrated(PA and/or ST)guidelines were associated with less pronounced difficulties in making friends and arguing(p<0.05).Meeting 24-HMB guidelines in an isolated and integrated manner are linked to better cognitive performance and fewer internalizing and externalizing problems in preterm youth.Conclusion:Results suggest that advocating for the implementation of the 24-HMB guidelines may reduce cognitive challenges and behavioral issues,which is of high relevance for improving public health.Future longitudinal studies in preterm youth should investigate how modifying specific 24-HMB behaviors,especially ST,influence cognitive difficulties,internalizing and externalizing problems in this vulnerable population.

Research on the Employment View of Acupuncture and Tuina Undergraduates in Minority Border Areas from Students’ Perspective

With the popularization of higher education in China,the employment situation of college students is more complex and severe.This paper adopts the questionnaire method to explore the employment view of acupuncture and tuina undergraduates of Yunnan University of Traditional Chinese Medicine.The employment concept of acupuncture and tuina undergraduates in the minority border areas has changed greatly.After graduation,97.95%of students choose to work in fields related to medicine and acupuncture,prefer positions close to home,and are attracted to high-salary companies,among other factors.Therefore,enhancing the competitive advantages of medical students by guiding their career planning,providing employment selection advice,fostering innovation and entrepreneurship,improving basic skills,and offering graduate entrance examination guidance is crucial for broadening their employment opportunities.

Experimental and numerical studies of Ca(OH)_(2)/CaO dehydration process in a fixed-bed reactor for thermochemical energy storage

The Ca(OH)_(2)/CaO thermochemical energy storage(TCES)system based on calcium looping has received extensive attention owing to its high energy storage density,prolonged energy storage time,and environmental friendliness.The heat storage process of the Ca(OH)_(2)/CaO TCES system in a mixed heating reactor was evaluated in this study,by employing a combination of direct and indirect heating modes.The dehydration process was studied experimentally,and a numerical model was established and verified based on the experimental results.The dehydration behavior of 500 g of Ca(OH)_(2) powder was investigated in a fixed-bed reactor with mixed heating.The experimental and simulation results indicated that mixed heating causes combined centripetal and horizontal propulsion.Heat input is the main limiting factor in the heat storage process,because the radial advance of the reaction is hindered by the low thermal conductivity of the solid reactant particles.Heat transmission partitions were added to enhance the performance of the reactor.The performance of the modified reactor was compared with that of a conventional reactor.The radial heat transmission partitions in the modified reactor effectively enhance the energy storage rate and reduce the reaction time by 59.5%compared with the reactor without partitions.

Validity and Reliability of the Preference for and Tolerance of the Intensity of Exercise Questionnaire among Chinese College Students

The rising prevalence of physical inactivity is in all age groups(e.g.,in college students)a major public health issue as not meeting the recommended minimum amount of regular physical activity is linked to adverse health events.Vice versa,there is mounting evidence that achieving the recommended amount of regular physical activity is a vital element to prevent chronic diseases,but there is often an insufficient adherence to planned and structured forms of physical activity(i.e.,physical exercises).In this context,there is a large body of evidence indicating that exercise adherence is,among other factors,influenced by exercise-related affective responses.The Preference for and Tolerance of the Intensity of Exer-cise Questionnaire(PRETIE-Q)has been developed to measure these affective responses(e.g.,to specific exercise inten-sities).So far,no validated Chinese version of the PRETIE-Q has been available in the literature.To address this gap in literature,the present study developed and validated a Chinese version of the PRETIE-Q in a large sample of Chinese college students.Data from a total of 1117 college students were collected for analyses concerning factorial validity and construct validity.The re-test reliability was established using a sample of 150 randomly selected participants.In addition,the level of regular physical activity(PA),cardiorespiratoryfitness(CRF),and resilience were used to examine possible links with two domains(preference and tolerance)of the PRETIE-Q.Our results showed that a Chinese version of the PRETIE-Q has a goodfit and reliability(Cronbach’sαof 0.72 to 0.85 for preference and tolerance,respectively;ICC:r=0.72 of preference and r=0.67 of tolerance;fit indices:χ^(2)=21.612,df=19,p>0.05,TLI=0.997,CFI=0.998,RMSEA=0.016,SRMR=0.024).Secondly,positive associations of intensity-tolerance with PA,CRF,and resilience were observed.In summary,this study indicates that the Chinese version of the PRETIE-Q has sound psychometric properties and can be used in Chinese college students.The adapted version of the PRETIE-Q paves the way for further research on exer-cise-related affective responses in Chinese-speaking samples,although the generalizability of ourfindings needs to be established for other cohorts such as adolescents and older people with and without chronic diseases.

Freestanding and Flexible Interfacial Layer Enables Bottom-Up Zn Deposition Toward Dendrite-Free Aqueous Zn-Ion Batteries

Aqueous rechargeable zinc ion batteries are regarded as a competitive alternative to lithium-ion batteries because of their distinct advantages of high security,high energy density,low cost,and environmental friendliness.However,deep-seated problems including Zn dendrite and adverse side reactions severely impede the practical application.In this work,we proposed a freestanding Zn-electrolyte interfacial layer composed of multicapsular carbon fibers(MCFs)to regulate the plating/stripping behavior of Zn anodes.The versatile MCFs protective layer can uniformize the electric field and Zn^(2+)flux,meanwhile,reduce the deposition overpotentials,leading to high-quality and rapid Zn deposition kinetics.Furthermore,the bottom-up and uniform deposition of Zn on the Zn-MCFs interface endows long-term and high-capacity plating.Accordingly,the Zn@MCFs symmetric batteries can keep working up to 1500 h with 5 mAh cm^(−2).The feasibility of the MCFs interfacial layer is also convinced in Zn@MCFs||MnO_(2) batteries.Remarkably,the Zn@MCFs||α-MnO_(2)batteries deliver a high specific capacity of 236.1 mAh g^(−1)at 1 A g^(−1)with excellent stability,and maintain an exhilarating energy density of 154.3 Wh kg^(−1) at 33%depth of discharge in pouch batteries.

A low-cost in-situ CO_(2) sensor based on a membrane and NDIR for long-term measurement in seawater

The multi-point simultaneous long-term measurement of CO_(2) concentration in seawater can provide more-valuable data for further understanding of the spatial and temporal distribution of CO_(2).Thus,the requirement for a low-cost sensor with high precision,low power consumption,and a small size is becoming urgent.In this work,an in-situ sensor for CO_(2) detection in seawater,based on a permeable membrane and non-dispersive infrared(NDIR)technology,is developed.The sensor has a small size(Ф66 mm×124 mm),light weight(0.7 kg in air),low power consumption(<0.9 W),low cost(<US$1000),and high-pressure tolerance(<200 m).After laboratory performance tests,the sensor was found to have a measurement range of(0–2000)×10^(-6),and the gas linear correlation R^(2) is 0.99,with a precision of about 0.98%at a sampling rate of 1 s.A comparison measurement was carried out with a commercial sensor in a pool for 7 days,and the results showed a consistent trend.Further,the newly developed sensor was deployed in Qingdao nearshore water for 35 days.The results proved that the sensor could measure the dynamic changes of CO_(2) concentration in seawater continuously,and had the potential to carry out long-term observations on an oceanic platform.It is hoped that the sensor could be applied to field ocean observations in near future.

美瞳的独白

将美瞳拟人化,通过美瞳独白的形式,介绍了美瞳的结构和不当配戴美瞳的危害,并给出了配戴美瞳的建议。通过科学性、趣味性兼备方式,让读者深入了解美瞳,加强美瞳配戴的安全意识。

cPCN-Regulated SnO_(2) Composites Enables Perovskite Solar Cell with Efficiency Beyond 23%

Efficient electron transport layers(ETLs)not only play a crucial role in promoting carrier separation and electron extraction in perovskite solar cells(PSCs)but also significantly affect the process of nucleation and growth of the perovskite layer.Herein,crystalline polymeric carbon nitrides(cPCN)are introduced to regulate the electronic properties of SnO_(2) nanocrystals,resulting in cPCN-composited SnO_(2)(SnO_(2)-cPCN)ETLs with enhanced charge transport and perovs-kite layers with decreased grain boundaries.Firstly,SnO_(2)-cPCN ETLs show three times higher electron mobility than pristine SnO_(2) while offering better energy level alignment with the perovskite layer.The SnO_(2)-cPCN ETLs with decreased wettability endow the perovskite films with higher crystallinity by retarding the crystallization rate.In the end,the power conversion efficiency(PCE)of planar PSCs can be boosted to 23.17%with negligible hysteresis and a steady-state efficiency output of 21.98%,which is one of the highest PCEs for PSCs with modified SnO_(2) ETLs.SnO_(2)-cPCN based devices also showed higher stability than pristine SnO_(2),maintaining 88%of the initial PCE after 2000 h of storage in the ambient environment(with controlled RH of 30%±5%)without encapsulation.

The Effects of Therapeutic Horseback Riding Program on Motor Skills inChildren with Autism Spectrum Disorder

Therapeutic horseback riding(THR)as an animal-assisted intervention is one of the innovative approaches emer-ging in the treatment for children with autism spectrum disorder(ASD).The current study was designed to inves-tigate the effects of a 12-week,twice a week THR program on motor skills in sixty-eight children with ASD aged 5–10 years old.All participants selected met the DSM-V criteria for ASD,and a total offifty-three participants completed the study.A randomized controlled trial design was utilized for the study.Data was collected via a pre-THR test,interim-THR test,and post-THR test to investigate the possible changes in motor skills throughout the 12-week THR program.Results showed that the THR program significantly improved overall motor skills across time points(p<0.05)and sub-skills of run,gallop and two-hand catch(as compared to the control group,p<0.05).In conclusion,the THR program may be an effective option for improving motor skills in children with ASD and further investigation with a longer period of intervention is warranted.

Study of double-chamber air arc plasma torch and the application in solid-waste disposal

Arc plasma can be applied in hazardous solid waste disposal for higher temperature than common heating methods,but some practical issues exist in practical engineering application.In this study,an air arc plasma torch with double chambers and magnetic controlling is designed to realize wide variable power and long electrode life.The detailed characteristics and laws of the air arc are studied.The condition parameters of arc current(I),air flow rate(G)and the structure parameters of inlet area ratios and electrode diameters influence both the arc voltage and arc root positions.The arc rotating driven by magnetic field effectively lengthens the electrode life.The gasification process and product of organic wastes by air plasma are influenced largely by the waste compositions and the air flow rate.A furnace structure with more even atmosphere and longer residence time should be considered for better gasification.Oxygen-deficient environment is important to suppress NOxformation during the application of air plasma.Inorganic solid wastes can be melt by the air plasma and cooled down to form compact vitreous structures in which heavy metals can be locked and the leaching rates significantly decrease down.

Elucidation of the hepatoprotective effect and mechanism of Melastoma dodecandrum Lour. based on network pharmacology and experimental validation

Objective:To systematically explore the effect and mechanism of melastomatis dodecandri herba(Melastoma dodecandrum Lour.)in the treatment of hepatitis based on network pharmacology.Method:We evaluated the hepatoprotective effects of M.dodecandrum in concanavalin A(Con A)-induced hepatitis in mice by assessing survival rate,histological analysis,serum transaminases,and related cytokines.Then the mechanism of action was predicted by a network pharmacology-based strategy.Based on the results,we measured the hepatic expression of related genes at mRNA level and proteins related to the phosphoinositide 3-kinase(PI3K)/protein kinase B(Akt)and nuclear factorkappa B(NF-кB)pathways.Results:Our study results clearly demonstrated that M.dodecandrum pretreatment significantly alleviated liver injury.This was demonstrated by an increase in survival rate,decreased severity of liver damage,and reduced serum transaminase levels compared with those in the Con A group.Moreover,M.dodecandrum significantly reduced the serum levels of tumor necrosis factor-a,interleukin-6,and interferon-g and increased the liver levels of superoxide dismutase,which indicated that M.dodecandrum exhibits anti-inflammatory and antioxidant activities.On the basis of network pharmacology,50 nodes were selected as major hubs based on their topological importance.Pathway enrichment analyses indicated that the putative targets of M.dodecandrum mostly participate in various pathways associated with the anti-inflammation response,which implies the underlying mechanism by which M.dodecandrum acts on hepatitis.Real-time fluorescent quantitative PCR analysis showed that M.dodecandrum downregulates the mRNA expression of interleukin-6,Toll-like receptor 7,interleukin-1 receptor-associated kinase-4,NF-кB and tumor necrosis factor-a in liver tissues.Western blotting showed that M.dodecandrum pretreatment protected against inflammation through activating the PI3K-Akt pathway by upregulating phosphorylated Akt(p-Akt)expression and suppressing NF-кB activation by inhibiting the phosphorylation of IKK,IkBa,and p65.Conclusion:The present work demonstrated the hepatoprotective effects of M.dodecandrum by regulating the PI3K/Akt and NF-кB pathways in Con A-induced mice,which provide insights into the treatment of hepatitis using M.dodecandrum.

Effects of Health Qigong Exercise on Depression and Anxiety in Patients with Parkinson’s Disease

Objective: This study explored the effects of Health Qigong exercise on depression and anxiety in patients withParkinson’s disease (PD). Methods: A total of 42 volunteers who met the inclusion criteria were recruited andrandomly allocated into the experimental group and the control group. The experimental group carried out60-minute sessions of Health Qigong exercise five times a week for 12 weeks while the control group did not performany regular physical exercise. Data on cognitive impairment, psychomotor retardation, somatic anxiety,weight loss and sleep disorders, the sum score of the 17-item Hamilton Depression Rating Scale (HDRS-17), stateanxiety, trait anxiety as well as the sum score of the State-Trait Anxiety Inventory (STAI) were collected for threerepeated measurements (baseline, 6, and 12 weeks). Results: Significant differences were observed in depression,state anxiety, trait anxiety, cognitive impairment and psychomotor retardation in the experimental group but nodifference in somatic anxiety, weight loss and sleep disorders. Conclusion: Health Qigong exercise can pose positivepsychological effects and alleviate the depression and anxiety in patients with Parkinson’s disease. It can beapplied as an accessible supplement to the existent drug treatment for PD.

Simultaneously enhancing the hot workability and room-temperature strength of Ti-6Al-4V alloy via adding Mo and Fe

Reducing the hot working temperature and high-temperature deformation resistance of titanium alloy to improve hot rolling and hot extrusion workability of products with thin walls and complex section shapes has always been an important topic in the field of titanium alloy processing.This paper proposed a strategy of adding Mo and Fe elements to simultaneously reduce the hot working temperature and high-temperature deformation resistance of Ti-6Al-4V alloy.The effects of Mo and Fe contents on the mi-crostructure,β transus temperature(Tp),and high-temperature flow stress(HFS)of Ti-6Al-4V-xMo-xFe(x=0-5)alloys were investigated.The results showed that adding Mo and Fe can substantially reduce the Tp and HFS of the alloy,and greatly improve its room-temperature strength.Compared with com-mercial Ti-6Al-4V samples,the T_(β) of Ti-6Al-4V-2Mo-2Fe and Ti-6Al-4V-3Mo-3Fe samples was decreased by 68-98 ℃,and the HFS at 800-900 ℃ was decreased by 37.8%-46.0%.Compared with hot-rolled Ti-6Al-4V samples,the room-temperature tensile strength of hot-rolled Ti-6Al-4V-2Mo-2Fe samples was increased by about 30%,while the elongation hardly decreased.The increased strength was mainly at-tributed to fine grain strengthening and solid solution strengthening.The hot workability and room-temperature strength of Ti-6Al-4V alloy can be significantly improved by adding 2-3 wt.%Mo and Fe simultaneously.

Multicolor upconversion reversible modulations in YNbO_(4):Er^(3+)/Tm^(3+)/Yb^(3+) photochromic materials

Photochromic materials with multicolor upconversion reversible modulations are attractive in optical switching devices.Herein,the fabricated YNbO_(4):Er^(3+)/Tm^(3+)/Yb^(3+) materials exhibit excellent photochromism and multicolor upconversion properties from green,red to near infrared(NIR) emissions with increasing Yb concentrations.Reversible multiband upconversion modulations are achieved by alternating light(365 and 405 nm) or thermal stimuli.After 365 nm irradiation,the luminescence color changes from yellow to red,the luminescent photoswitching contrast reaches up to 86.21%(green),82.12%(red) and 77.38%(NIR) in the Y_(0.83)Er_(0.01)Tm_(0.01)NbO_(4):0.15 Yb sample.Besides,the upconversion emission intensity before and after photochromic reaction shows remarkable change in a wide temperature range of 298-718 K.These results indicate that the Er^(3+)/Tm^(3+)/Yb^(3+) tri-doped YNbO_(4) materials can be a good candidate in optical switching and data storage applications.

底层不连续的多层连体结构的提升方案优选分析

随着建筑钢结构的发展,高层建筑群如雨后春笋般出现,两栋高层之间设置钢连体是常见的结构形式。目前,对于常规高空连体结构安装,大多采用地面拼装后整体提升至设计位置的安装方法。但针对底层不连续的多层连体结构,一方面地面拼装胎架高,存在高空作业,不经济又不安全;另一方面拼装时底层结构需进行加固,施工繁琐。因此制定更为经济、安全、快速的施工方案是当前施工的重点。以杭州云门项目为例,给出了累积提升与分层提升两种施工方案,并对两者从结构受力变形,施工经济性、安全性、时效性等方面进行衡量比选。在受力方面,采用上述两种方案施工,对于塔楼而言,杆件应力最大值差别较小,但采用分层提升施工构件的附加应力更小,受力更为合理;对于连体而言,杆件应力最大值基本相同,但采用分层提升的杆件应力总体偏小;对于提升加强杆而言,采用分层提升方案时加强杆最大轴力为10 905.27 kN,而采用累积提升方案时加强杆最大轴力为12 615.81 kN,前者较后者减小约13.6%,因此采用分层提升方案可降低对其截面的需求,从而便于在提升完成后进行拆除。在变形方面,采用上述两种方案施工,结构最大竖向变形均位于连体跨中,且变形值相差不大;而结构最大水平变形虽均位于塔楼顶层,但变形值有些许差别,分层提升变形值较小,这是由于采用分层提升,二次提升前连体上层结构与塔楼已连成一体,具备了一定的水平刚度。在施工方面,采用累积提升方案施工,下层结构在低空安装时,上层连体结构悬停时间较长,时效性差,且连体未与塔楼形成有效连接,施工安全性差;而采用分层提升方案,上层连体结构一次提升到位后直接进行补杆工作,使连体与塔楼初步形成有效连接,届时可同步进行下层三角区结构的拼装工作,时效性、安全性更佳。在经济性方面两者相差较小,分层提升对于提升设备的数量需求较高。结果表明,针对底层不连续的多层连体结构施工,分层提升法在结构受力及变形方面,施工经济性、安全性、时效性方面表现更佳。

基于最优化理论的大跨异形曲面结构单轴旋转法

近十年来,国内兴建了大量的机场、高铁站、会展中心等工程,具有建筑造型新颖、平面尺寸大(超大面宽、超大进深和较大高差)等特点,一般采用原位拼装提升或累积提升的施工工艺。由于上述施工方法存在拼装高度较高、高空作业量大、工艺复杂等问题,导致施工效率低、安全风险大、质量控制难。虽然旋转提升法对于降低拼装高度有显著的效果,但是多应用于跨度小、结构规整、提升吊点数量少的结构中,同时旋转过程中同步性较差,经常导致提升器窝缸甚至局部杆件受力过大而弯曲破坏的现象,针对大跨曲面屋盖钢结构施工仍处于技术空白期,存在适用局限性。依托杭州西站项目,系统介绍了大跨异形曲面结构确定旋转轴及旋转角度的两种方法,即双轴反复旋转法和基于最优化理论的单轴旋转法,并从经济性、安全性、实操性方面对两种方法及原位拼装提升法进行了对比:1)经济方面,基于最优化理论的单轴旋转法较双轴反复旋转法节省胎架用量5.8%,较原位拼装提升节省胎架用量406.8%。2)安全方面,采用单轴旋转施工与原位拼装提升施工结构杆件应力比差值不到0.05,而双轴旋转施工(换杆前)与原位拼装提升施工结构杆件应力比差值达1.31,这是由于采用双轴旋转施工,结构需分别绕两个方向旋转,旋转过程态与结构设计态位形差异较大,导致杆件内力分布不均匀,从而导致部分构件应力比较大,虽然可通过换杆加固的方式解决,但设计施工成本会相应增加。结构施工过程中虽然单轴旋转法的构件应力比与原位拼装提升法的差别不大,但是原位拼装提升法所设胎架高度高,存在大面积高空作业,工人施工安全性较差。3)实操方面,采用旋转提升可有效解决原位拼装提升带来的拼装胎架安装高度高、高空作业多等施工复杂性问题。而基于最优化理论的单轴旋转法相较于双轴反复旋转法,其可通过自编程序一步得到旋转提升参数的最优解,省时省力。且由于其确定的旋转轴及旋转角度是唯一的,施工时结构仅需绕单轴进行旋转,操作更为简便。结果表明:基于最优化理论的单轴旋转法更佳,其较好地弥补了原位拼装提升法、双轴反复旋转法在大跨异形曲面屋盖钢结构应用中的技术缺陷和不足,为以后类似曲面屋盖结构的施工提供参鉴。

Simultaneous enhancement in mechanical and corrosion properties of Al-Mg-Si alloys using machine learning

Al-Mg-Si alloys with high strength and good corrosion resistance are regarded as desirable materials for all-aluminum vehicles.However,the traditional trial-and-error experimental methods are insufficient to address the trade-offbetween strength and corrosion resistance.In this work,a non-dominated sorting genetic machine-learning algorithm(NSGA-II)was employed to optimize the chemical composition,so as to simultaneously improve the strength and corrosion resistance.Three high-performance Al-Mg-Si alloys with low Mg,Si,and Cu contents were successfully developed,where the yield strength(YS),ultimate tensile strength(UTS),and the elongation(δ)reached 375-380 MPa,410-416 MPa,and 13.7%-15.2%,re-spectively.Compared with higher-Cu-content 6013 alloy,the YS and UTS of the present alloys increase by about 60 MPa,and the intergranular corrosion resistance is also significantly improved.Microstruc-ture characterization demonstrated thatβ’’and QP phases introduced a significant synergistic precipita-tion strengthening effect;the dispersoids formed by trace Mn,Cr,Fe,Zr,and Ti contributed dispersion strengthening effect;and the good pitting corrosion resistance is attributed to lower Mg and Si contents.