聚合物三腔微管挤出口模结构对胀大变形的影响

聚合物熔体的模内流动状态与模外胀大变形直接影响微挤出制品的成型质量。文中基于Carreau模型,采用数值模拟方法,研究了聚合物三腔微管挤出过程中口模壁厚差与空心度结构特征对胀大变形行为的影响。结果表明,影响挤出胀大变形程度的关键因素是口模出口附近的轴向速度分布;内外壁厚差会导致较大壁厚位置处对应的型坯厚度增大,而较小壁厚位置处的型坯厚度减小,壁厚差变化对薄壁区域壁厚变形影响较大,达到91.4%;空心度减小能提升口模出口附近轴向速度分布均匀性,减小了70.1%的变形程度;基于胀大变形规律逆向补偿设计了口模形状与尺寸,明显改善了制品成型质量。研究结果对聚合物多腔微管的口模结构优化设计具有理论意义与工程应用价值。

新工科背景下应用化学综合实验课程思政育人实践

针对新工科理念和课程思政的要求,避免专业教育和思政教育“两张皮”的问题,从教材、课程教学和平台建设等方面介绍了新工科理念和课程思政在应用化学综合实验中的有机融合实践。在前期课程教学基础和初步实践基础上,提出了建设配套教材、发挥线上线下教学、搭建校内科研与工程实践平台、拓展校外实践基地等具体的改革路径,将课程思政全方位融入教学活动中,构建了应用化学综合实验课程思政育人新体系,助力新工科背景下新兴应用型人才培养。该实践可为其他实验课程开展新工科背景下课程思政改革提供参考。

Enhanced rainfall in North China in July 2021:Role of the North Pacific SST gradient

2021年7月,华北地区的降水量突破1980年以来的极值,这与太平洋海温异常的经向梯度相吻合.研究表明,西北太平洋正海温异常与热带中太平洋负海温异常之间的梯度是2021年7月华北地区降水异常偏多的主要原因,该梯度使得西北太平洋反气旋及其南部的气旋北移,汇合的偏东风将大量水汽从海洋输送到华北地区,使得华北地区降水偏多.同时,太平洋海温异常的经向梯度可能在对流层低层触发异常的反向哈德利环流,伴随着南风异常,使得季风环流增强,雨带偏北.

Survival prognostic analysis of laparoscopic D2 radical resection for locally advanced gastric cancer: A multicenter cohort study

BACKGROUND With the development of minimally invasive surgical techniques,the use of laparoscopic D2 radical surgery for the treatment of locally advanced gastric cancer(GC)has gradually increased.However,the effect of this procedure on survival and prognosis remains controversial.This study evaluated the survival and prognosis of patients receiving laparoscopic D2 radical resection for the treatment of locally advanced GC to provide more reliable clinical evidence,guide clinical decision-making,optimize treatment strategies,and improve the survival rate and quality of life of patients.METHODS A retrospective cohort study was performed.Clinicopathological data from 652 patients with locally advanced GC in our hospitals from December 2013 to December 2023 were collected.There were 442 males and 210 females.The mean age was 57±12 years.All patients underwent a laparoscopic D2 radical operation for distal GC.The patients were followed up in the outpatient department and by telephone to determine their tumor recurrence,metastasis,and survival.The follow-up period ended in December 2023.Normally distributed data are expressed as the mean±SD,and normally distributed data are expressed as M(Q1,Q3)or M(range).Statistical data are expressed as absolute numbers or percentages;theχ^(2) test was used for comparisons between groups,and the Mann-Whitney U nonparametric test was used for comparisons of rank data.The life table method was used to calculate the survival rate,the Kaplan-Meier method was used to construct survival curves,the log rank test was used for survival analysis,and the Cox risk regression model was used for univariate and multifactor analysis.RESULTS The median overall survival(OS)time for the 652 patients was 81 months,with a 10-year OS rate of 46.1%.Patients with TNM stages II and III had 10-year OS rates of 59.6%and 37.5%,respectively,which were significantly different(P<0.05).Univariate analysis indicated that factors such as age,maximum tumor diameter,tumor diffe-rentiation grade(low to undifferentiated),pathological TNM stage,pathological T stage,pathological N stage(N2,N3),and postoperative chemotherapy significantly influenced the 10-year OS rate for patients with locally advanced GC following laparoscopic D2 radical resection for distal stomach cancer[hazard ratio(HR):1.45,1.64,1.45,1.64,1.37,2.05,1.30,1.68,3.08,and 0.56 with confidence intervals(CIs)of 1.15-1.84,1.32-2.03,1.05-1.77,1.62-2.59,1.05-1.61,1.17-2.42,2.15-4.41,and 0.44-0.70,respectively;P<0.05].Multifactor analysis revealed that a tumor diameter greater than 4 cm,low tumor differentiation,and pathological TNM stage III were independent risk factors for the 10-year OS rate in these patients(HR:1.48,1.44,1.81 with a 95%CI:1.19-1.84).Additionally,postoperative chemotherapy emerged as an independent protective factor for the 10-year OS rate(HR:0.57,95%CI:0.45-0.73;P<0.05).CONCLUSION A maximum tumor diameter exceeding 4 cm,low tumor differentiation,and pathological TNM stage III were identified as independent risk factors for the 10-year OS rate in patients with locally advanced GC following laparoscopic D2 radical resection for distal GC.Conversely,postoperative chemotherapy was found to be an independent protective factor for the 10-year OS rate in these patients.

3层共挤模具交汇夹角对单层厚度及离模胀大的调控机制

聚合物共挤模具结构对制品成型质量有着重要影响,尤其是模具交汇夹角对熔体厚度及离模胀大有着明显的影响。文中采用Carreau黏度模型和Picard迭代计算方法,深入研究了外层为聚十二内酰胺(PA12)、中层为乙烯-醋酸乙烯酯共聚物(EVA)和内层为聚丙烯(PP)的3层微管共挤过程的数值模拟。结果表明,外层熔体交汇夹角增大时,PA12厚度增加,EVA和PP厚度减小,内外径均减小,胀大率增大;中层熔体交汇夹角增大时,EVA厚度增大,PA12和PP厚度减小,内外径均减小,胀大率减小;两处熔体交汇夹角同时增大时,PA12和EVA厚度增大,PP厚度减小,内外径均减小,胀大率增大。3层共挤实验证明了模拟结果的正确性与有效性。该研究结果能够为聚合物多层共挤模具的流道结构设计提供了有价值的参考。

创新社会实践课程体系,助力专业人才培养——以广西师范大学应用化学专业为例

以提升学生的专业素养为目标,从教学团队、课程内容、教学资源、教学模式、考核方式等方面对应用化学专业社会实践课程进行改革,构建了凸显专业性和创新性的逐级递进式社会实践课程内容体系,实施了线上线下相结合的多元化教学策略,实现了专业教育、社会服务和课程思政的高度融合,提高了地方院校应用化学专业人才的培养质量。

Mixing trait-based corn(Zea mays L.)cultivars increases yield through pollination synchronization and increased cross-fertilization

Abiotic stress such as high temperature at flowering is one of many conditions reducing yield of corn(Zea mays L.).Mixing corn cultivars with diverse functional traits increases within-crop diversity and provides a potential means of mitigating yield losses under stress conditions.We conducted a three-year field study to investigate the effects of cultivar mixtures on kernel setting rate,pollen sources,and yield.This study consisted of six treatments,including two high temperature-tolerant(HTT)monocrops of WK702 and DH701,two high temperature-sensitive(HTS)monocrops of DH605 and DH662,and two HTT–HTS mixtures of WK702-DH605 and DH701-DH662.The anthesis–silking interval(ASI)was 0.9–1.6 days shorter in mixtures than in monocrops.Kernel setting rate was increased in mixtures(86.4%–88.7%)compared with those in monocrops(74.7%–84.1%)as a result of synchrony and complementarity of pollination.Grain yields of the HTT–HTS mixtures increased by 13.3%–18.7%,equivalent to 1169 to1605 kg ha^(-1),in comparison with HTS corn monocrops.The results of SSR markers showed that crossfertilization percentage in corn cultivar mixtures ranged from 29.3%to 47.8%,partially explaining yield improvement.Land equivalent ratio(LER)was 1.12 for corn mixtures and the partial land equivalent ratio(e.g.,>0.5)showed the complementary benefits in corn mixtures.The results indicated that mixing corn cultivars with diverse flowering and drought-tolerance traits increased yields via pollination synchrony.

Interdecadal Enhancement in the Relationship between the Western North Pacific Summer Monsoon and Sea Surface Temperature in the Tropical Central-Western Pacific after the Early 1990s

This study reveals the strengthened interdecadal relationship between the western North Pacific summer monsoon(WNPSM)and tropical central-western Pacific sea surface temperature anomaly(SSTA)in summer after the early 1990s.In the first period(1979–91,P1),the WNPSM-related precipitation anomaly and horizontal wind anomaly present themselves as an analogous Pacific-Japan(PJ)-like pattern,generally considered to be related to the Niño-3 index in the preceding winter.During the subsequent period(1994–2019,P2),the WNPSM-related precipitation anomaly presents a zonal dipole pattern,correlated significantly with the concurrent SSTA in the Niño-4 and tropical western Pacific regions.The negative(positive)SSTA in the tropical western Pacific and positive(negative)SSTA in the Niño-4 region,could work together to influence the WNPSM,noting that the two types of anomalous SSTA configurations enhance(weaken)the WNPSM by the positive(negative)phase PJ-like wave and Gill response,respectively,with an anomalous cyclone(anticyclone)located in the WNPSM,which shows obvious symmetry about the anomalous circulation.Specifically,the SSTA in Niño-4 impacts the WNPSM by an atmospheric Gill response,with a stronger(weaker)WNPSM along with a positive(negative)SSTA in the Niño-4 region.Furthermore,the SSTA in the tropical western Pacific exerts an influence on the WNPSM by a PJ-like wave,with a stronger(weaker)WNPSM along with a negative(positive)SSTA in the tropical western Pacific.In general,SSTAs in the tropical western Pacific and Niño-4 areas could work together to exert influence on the WNPSM,with the effect most likely to occur in the El Niño(La Niña)developing year in P2.However,the SSTAs in the tropical western Pacific worked alone to exert an influence on the WNPSM mainly in 2013,2014,2016,and 2017,and the SSTAs in the Niño-4 region worked alone to exert an influence on the WNPSM mainly in Central Pacific(CP)La Niña developing years.The sensitivity experiments also can reproduce the PJ-like wave/Gill response associated with SSTA in the tropical western Pacific/Niño-4 regions.Therefore,the respective and synergistic impacts from the Niño-4 region and the tropical western Pacific on the WNPSM have been revealed,which helps us to acquire a better understanding of the interdecadal variations of the WNPSM and its associated climate influences.

Enhanced phase sensitive amplification towards improving noise immunity

Quantum states are essential resource for quantum-enhanced applications.Loss incurred in the distribution channel,however,dissipates the high signal-to-noise ratio advantage enjoyed by the squeezed state.Here,we first demonstrate noise immunity enhancement by using phase-sensitive amplifier(PSA)with measurement-based noiseless linear amplifier(MB-NLA).We explore the signal transfer capability with the amplifier in a noisy channel.The MB-NLA enhanced PSA has obvious suppression effect on channel noises,especially it has improvement for the noise contaminated signal.Better performance can be achieved by flexibly adjusting amplifier parameters.With the amplifier,it is promising to overcome the entanglement-distribution loss and show its superiority in squeezing based quantum sensing.

单模具多规格聚乳酸微管挤出成型工艺

系统研究了聚乳酸微管的挤出成型工艺,获得了注气量、螺杆转速、牵引速度对微管外径、壁厚和椭圆度的影响规律。实验结果表明,注气量、螺杆转速、牵引速度对微管外径和壁厚的影响显著,且呈非线性变化。其中,牵引速度和螺杆转速相对于注气量对微管外径的影响程度较大;螺杆转速、牵引速度和注气量对微管壁厚的影响程度依次减弱。注气量直接影响微管截面的椭圆度,注气量越大,椭圆度越小,在注气量较小时,注气量增大1倍,椭圆度可降低68%。通过改变牵引速度、螺杆转速、注气量及其组合,可以达到采用1套模具顺序挤出4种规格聚乳酸微管的目的。

尼龙6棒材挤出成型及制品性能

针对尼龙6(PA6)棒材挤出成型性较差的工程问题,实验研究了PA6材料的流变特性和挤出成型的合理温度区间,采用数值分析方法研究了PA6棒材挤出模具加热区流道结构特征参数对熔体温度分布和剪切速率的影响规律,分析了螺旋冷却水道的温度分布状况及冷却效果。结果发现,PA6挤出成型温度控制在230～240℃,能够有效保证其挤出成型性并避免材料降解;增大挤出模具加热区压缩段长度能够降低熔体黏性生热导致的温升和熔体局部剪切速率,增大释放段长度能够降低熔体局部的剪切速率,但是对熔体温升基本无影响;挤出模具采用螺旋冷却水道冷却定型,可以使PA6棒材的冷却更加均匀。通过改进挤出模具设计和冷却定型系统,有效改善了PA6挤出棒材制品的内在和外观质量。

RETINOIC ACID DOWN-REGULATES BONE MORPHOGENETIC PROTEIN 7 EXPRESSION IN RAT WITH CLEFT PALATE

Objective To evaluate the effects of retinoic acid （RA） on expression of bone morphogenetic protein 7 （ BMP-7 ） in rat fetus with cleft palate, and the effects of RA on proliferation and apoptosis of osteoblasts. Methods All-trans RA （ATRA） was used to induce congenital cleft palate in Wistar rat. BMP-7 mRNA expression in maxillary bone tissue of fetal rats was measured by Northern blotting analysis. Flow cytometry and MTF assay were used to measure the apoptosis and proliferation of ATRA-treated MC-3T3-E1 cells. BMP-7 mRNA and protein expressions in ATRA-treated MC-3T3-E1 cells were detected by RT-PCR and Western blotting analysis. Remilts ATRA could induce cleft palate of rat fetus. The incidence rate of cleft palate induced by 100 mg/kg AT-RA （45.5%） was significantly higher than 50 mg/kg ATRA （ 12.5%, P 〈 0. 05 ）. BMP-7 mRNA expression decreased in maxillary bone tissue of rat fetus with cleft palate. MC-3T3-E1 cells proliferation treated with 1 × 10^-6 mol/L ATRA decreased by 60%, the cell apoptosis increased by 2 times. BMP-7 mRNA and protein levels in MC-3T3-E1 cells treated with 1 × 10^-6 mol/L ATRA decreased by 60% and 80%, respectively, compared with ATRA-untreated cells （ P 〈 0.05 ）. Conclusions BMP-7 may play an important role in embryonic palate development. RA may possess the ability to down-regulate cell proliferation through regulation of BMP-7 gene expression.

Relationship between Occurrence and Progression of Lung Cancer and Nocturnal Intermittent Hypoxia, Apnea and Daytime Sleepiness

The possible relationship between lung cancer and nocturnal intermittent hypoxia,apnea and daytime sleepiness,especially the possible relationship between the occurrence and progression of lung cancer and obstructive sleep apnea syndrome (OSAS) was explored.Forty-five cases of primary lung cancer suitable for surgical resection at the Third Affiliated Hospital of Kunming Medical University between January 2017 and December 2017 were recruited (lung cancer group),and there were 45 patients in the control group who had no significant differences in age,sex and other general data from lung cancer group.The analyzed covariates included general situation,snore score,the Epworth Sleeping Scale (ESS),Pittsburgh Sleep Quality Index (PSQI),apnea and hypopneas index (AHI),oxygen desaturation index 4 (ODk),lowest arterial oxygen saturation [LSpCh (%)],oxygen below 90% of the time [T90%(min)],the percentage of the total recorded time spend below 90% oxygen saturation (TS90%),to explore the possible relationship between lung cancer and above indicators.The participants were followed up for one year.The results showed that:(1) There was significant difference in body mass index (BMI),ESS,AHI,T90%(min),TS90%,ODh,snore score and LSpCh (%) between lung cancer group and control group (P<0.05).There was no statistically significant difference in age,gender,PSQI score,incidence of concurrent hypertension,diabetes and coronary heart disease (CHD),and smoking history between the two groups (P>0.05);(2) Patients in the lung cancer group were divided into OSAS subgroup and non- OSAS subgroup according to the international standard for the diagnosis of OSAS.There was significant difference in BMI,age,staging,incidence of concurrent hypertension and concurrent CHD,snore score,ESS score,T90%(min),TS90%,ODh and LSpCh (%) between OSAS subgroup and non-OSAS subgroup (P<0.05).There was no statistically significant difference in gender,PSQI score,incidence of concurrent diabetes,smoking history and lung cancer type between the two groups (P>0.05);(3) AHI was strongly negatively correlated with the LSpCh (%) and positively with ESS,staging,snoring score,T90%(min),TS90%,ODh and BMI (P<0.05);(4) There were 3 deaths,5 cases of recurrence,and 4 cases of metastasis in OSAS subgroup;and there was 1 death,4 cases of recurrence and 2 cases of metastasis in non-OSAS subgroup during the follow-up period of one year,respectively.There was no significant difference in mortality,recurrence rate and metastasis rate between the two subgroups,and the total rate of deterioration in OSAS subgroup was significantly increased compared to the non-OSAS subgroup (P<0.05).It was concluded that the patients with lung cancer are prone to nocturnal hypoxemia,apnea,snoring and daytime sleepiness compared to control group.The incidence of OSAS in patients with lung cancer was higher,and the difference in the hypoxemia-related indicators was statistically significant.The mortality,recurrence rate,and metastasis rate increases in lung cancer patients with OSAS during the one-year follow-up period,suggesting that OSAS may be a contributing factor to the occurrence and progression of lung cancer.

Multi-port cavity model and low-level RF systems design for VHF gun

Very high frequency(VHF) photocathode guns have excellent performance and are being increasingly selected as electron sources for high-repetition-rate X-ray free-electron lasers. As a highly loaded quality factor cavity, the VHF gun requires high stability in the amplitude and phase of the cavity field. However, the gun is microwave powered by two solid-state power sources through two separate power couplers. The input difference between the two power couplers will influence the stability of the cavity field. To systematically study this influence and obtain measurement formulae, a multi-port VHF gun LCR circuit model is built and analyzed. During the warm-up condition, the cavity structure will be deformed due to the large-scale change in the cavity temperature. Then, the deformation will result in cavity resonant frequency changes. To prevent the mechanic tuner from suffering damages due to the frequent and long-distance movement for correcting the cavity resonant frequency, a self-excited loop(SEL) control system is considered for changing the loop phase and make the loop frequency follow the resonant frequency. In this study, a steady-state model of the VHF gun cavity is built for obtaining the optimal input coupler coefficient and the stability requirement of the forward voltage. Then, the generator-driven resonator and SEL control system, which combine with the VHF multiport modeling, are modeled and simulated. The simulated results show that the SEL system can perfectly operate in the process of condition and warm-up.

Hierarchical and self-supporting honeycomb LaNi_5 alloy on nickel foam for overall water splitting in alkaline media

Ni-based metallic foams possessing large specific surfaces and open cell structures are of specific interest as catalysts or catalyst carriers for electrolysis of water.Traditional fabrication of Nickel foam limits the element modification choices to several inert transition metals only on polymer foam precursor and subsequent preparation of foam-based catalysts in aqueous solution or organic electrolyte.To expand the modification horizon,molten salt with wide electrochemical window and fast ion diffusion can achieve the reduction of highly active elements.Herein,we reported is a general and facile method to deposit directly of highly reactive element La and prepare hierarchical honeycomb LaNi_(5) alloy on Ni foam(ho-LaNi_(5)/NF).This self-supporting electrode presents excellent electrical coupling and conductivity between the Ni foam and LaNi_(5),which provides a 3D self-supported heterostructure with outstanding electrocatalytic activity and excellent durability for the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).It exhibits excellent overpotential(1.86 V)comparable to commercial coupled IrO_(2)//Pt/C(1.85 V)at a high current density of 100 m A cm^(-2).This work may pave the way for fabricating novel 3D self-supported honeycomb alloy that can be applied as electrode for usage of clean energy.

Towards atomic and close-to-atomic scale manufacturing

Human beings have witnessed unprecedented developments since the 1760s using precision tools and manufacturing methods that have led to ever-increasing precision,from millimeter to micrometer,to single nanometer,and to atomic levels.The modes of manufacturing have also advanced from craft-based manufacturing in the Stone,Bronze,and Iron Ages to precisioncontrollable manufacturing using automatic machinery.In the past 30 years,since the invention of the scanning tunneling microscope,humans have become capable of manipulating single atoms,laying the groundwork for the coming era of atomic and close-to-atomic scale manufacturing(ACSM).Close-to-atomic scale manufacturing includes all necessary steps to convert raw materials,components,or parts into products designed to meet the user’s specifications.The processes involved in ACSM are not only atomically precise but also remove,add,or transform work material at the atomic and close-to-atomic scales.This review discusses the history of the development of ACSM and the current state-of-the-art processes to achieve atomically precise and/or atomic-scale manufacturing.Existing and future applications of ACSM in quantum computing,molecular circuitry,and the life and material sciences are also described.To further develop ACSM,it is critical to understand the underlying mechanisms of atomic-scale and atomically precise manufacturing;develop functional devices,materials,and processes for ACSM;and promote high throughput manufacturing.

Sedimentology and sequence stratigraphy of the mixed clastic-carbonate deposits in the Late Paleozoic icehouse period:A case study from the northern Qaidam Basin

The widely-developed,mixed clastic-carbonate succession in the northern Qaidam Basin records the paleo-environment changes under the glacial activity during the Late Paleozoic icehouse period in the context of regional tectonic stability,however,the depositional environment and sequence stratigraphy characteristics of the mixed deposits is rarely reported and still not clear.Combined the latest drilling wells data,we analyzed the sedimentary and stratigraphic characterization of the mixed strata via detailed field outcrops and core observations and thin section microscopic observations and recognized three depositional systems,including progradational coastal system,incised valley system,and carbonate-dominated marine shelf system,and identified four third-order sequences,SQ1,SQ2,SQ3 and SQ4,consisting of LST,TST,and HST.The depositional environment is overall belonged to marine-continental transition context and shifted from marine to continental environment frequently,showing an evolutionary pattern from marine towards terrestrial-marine transition and then back into the marine environment again in the long-term,which was controlled by the regional tectonic subsidence and the high-frequency and large-amplitude sea-level changes due to the Late Paleozoic glacial activity.The result is of significance in understanding the evolution of the Qinghai-Tibet Plateau and the sedimentation-climate response.

Microstructural evolution and mechanical properties of forgedβ-solidifiedγ-TiAl alloy by different heat treatments

The microstructural evolution and tensile properties of a forged Ti−42Al−5Mn alloy subjected to different heat treatments were studied.The results showed that,when the forged alloy was aged at 800℃ for 24 h,the interlamellar spacing(λ)andγgrain size at colony boundaries are generally coarsened.Whereas,when the alloy was first annealed at 1300℃ and then aged at 800℃ for 24 h,this coarsening of related microstructures appears less pronounced.The suggested annealing temperatures for the forged Ti−42Al−5Mn alloy are in the range of 1250−1300℃.It was found that,on the condition of the same annealing system,both the strength and ductility were improved as the aging temperature changed from 1000 to 800℃.The secondary precipitatedβo(β_(o,sec))at colony boundaries could be responsible for improving the strength,and theγphase at colony boundaries with the grain size about 6μm might be one of the main reasons for the better ductility.

Using junction trees for structural learning of Bayesian networks

The learning Bayesian network （BN） structure from data is an NP-hard problem and still one of the most exciting chal- lenges in the machine learning. In this work, a novel algorithm is presented which combines ideas from local learning, constraint- based, and search-and-score techniques in a principled and ef- fective way. It first reconstructs the junction tree of a BN and then performs a K2-scoring greedy search to orientate the local edges in the cliques of junction tree. Theoretical and experimental results show the proposed algorithm is capable of handling networks with a large number of variables. Its comparison with the well-known K2 algorithm is also presented.

Multi-objective optimization for task offloading based on network calculus in fog environments

With the widespread application of wireless communication technology and continuous improvements to Internet of Things(IoT)technology,fog computing architecture composed of edge,fog,and cloud layers have become a research hotspot.This architecture uses Fog Nodes(FNs)close to users to implement certain cloud functions while compensating for cloud disadvantages.However,because of the limited computing and storage capabilities of a single FN,it is necessary to offload tasks to multiple cooperating FNs for task completion.To effectively and quickly realize task offloading,we use network calculus theory to establish an overall performance model for task offloading in a fog computing environment and propose a Globally Optimal Multi-objective Optimization algorithm for Task Offloading(GOMOTO)based on the performance model.The results show that the proposed model and algorithm can effectively reduce the total delay and total energy consumption of the system and improve the network Quality of Service(QoS).