Combining reinforcement learning with mathematical programming:An approach for optimal design of heat exchanger networks

Heat integration is important for energy-saving in the process industry.It is linked to the persistently challenging task of optimal design of heat exchanger networks(HEN).Due to the inherent highly nonconvex nonlinear and combinatorial nature of the HEN problem,it is not easy to find solutions of high quality for large-scale problems.The reinforcement learning(RL)method,which learns strategies through ongoing exploration and exploitation,reveals advantages in such area.However,due to the complexity of the HEN design problem,the RL method for HEN should be dedicated and designed.A hybrid strategy combining RL with mathematical programming is proposed to take better advantage of both methods.An insightful state representation of the HEN structure as well as a customized reward function is introduced.A Q-learning algorithm is applied to update the HEN structure using theε-greedy strategy.Better results are obtained from three literature cases of different scales.

Characteristics of mineral element content of alpine vegetation in permafrost region on Qinghai-Tibetan Plateau

The content characteristics of 16 elements （Al, Ca, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sr, and Zn） in 23 plant species collected from the Qinghai-Tibetan Plateau permafrost region were investigated using ICP-OES. Results show that the average contents of Ca, K, Mg, Fe and P were higher than 1,000 mg/kg, those of Al, Na, Zn and Cr ranged between 10-1,000 mg/kg and those of Cu, Li, Pb and Mo were less than 10 mg/kg. The levels of Al, Ca, K, Mg and Na were within the scope of the reported terrestrial plant element content, those of Sr, Fe and Cr were higher than the average of the terrestrial plants and the maximum content of Max was higher than the upper limit of the reported Mn content. The main character of the element content was of the Ca〉K type, however, in terms of Cyperaeeae species the element content character was K〉Ca type. The contents of Ca, Li, Mg and Sr in Gramineae and Cyperaeeae species were higher than those in other species and the contents of Ca, K, Mg, Fe, E A1 and Na in all collected plants were higher than those of other elements. Zn had weak variability with the lowest coefficient （i.e., 7.81%）, while other elements had strong variability. The ratio of maximum content to minimum content indicated Ca and K had less change than other elements in the Qinghai-Tibetan Plateau permafrost region. Element content of alpine vegetation in the Qinghai-Tibetan Plateau permafrost region mainly shows a positive correlation, among which the correlation coefficient between Al and Pb, Al and Fe, Mo and Cr, Pb and Fe, Sr and Li were higher than 0.9, and negative correlation had no statistical signifi- cance. The correlation between Al and Fe, Mg, Mn in the Qinghai-Tibetan Plateau permafrost region were consistent with that reported in Kunlun Mountains.

基于热带和热带外独立影响途径的中国东部冬季阴天频次的季节预测

本文利用中国东部1078个测站1961~2003年逐日云量数据资料,揭示了中国东部冬季阴天频次主模态的时空分布特征,探讨了其形成的两条独立影响途径,并根据影响机理建立了季节预测模型。结果表明:(1)中国东部冬季阴天频次的经验正交函数分解第一模态独立且显著,解释了其59%的总方差。该模态基本呈现空间一致型的分布,表现出显著的年际变率特征。当该模态为正位相时,北太平洋对流层低层存在显著的大尺度反气旋环流异常,其西侧异常偏南风能够将热带海洋的水汽输送至中国东部地区,导致该地区阴天频次增多。(2)前期8月和9月北太平洋副热带持续性海温异常的纬向偶极型分布(NPD)和副热带北大西洋海平面气压9至11月的短期变化(LPA)是该模态的两个主要驱动因子。当NPD中的西极为冷异常时,在局地低层气旋性异常环流的作用下冷海温异常向南平流,发展至热带西太平洋。而当热带西太平洋冷海温异常形成后,皮耶克里斯反馈作用能够发展和维持太平洋“西冷东暖”海表温度异常分布。“西冷东暖”的海表温度异常导致的热带纬向偶极型对流异常能够进一步激发北太平洋“北正南负”的偶极型高度场异常。北部反气旋异常西侧的偏南风有利于水汽输送至中国东部,从而导致阴天频次增多;LPA主要反映的是中高纬准定常罗斯贝波列由秋季至冬季的迅速转变。当副热带北大西洋海表面气压在前秋由正转负时,罗斯贝波列在东北亚上空冬季形成准正压的异常反气旋,其西侧偏南风异常同样能够导致中国东部阴天频次增多。(3)依据以上热带和热带外的两条独立影响机理途径,我们建立了具有物理意义的季节预测模型,利用2004~2013年间数据进行独立预测获得良好预测效果,可供业务预测部门参考和借鉴。

Natural product rhynchophylline prevents stress-induced hair graying by preserving melanocyte stem cells via theβ2 adrenergic pathway suppression

Norepinephrine(NA),a stress hormone,can accelerate hair graying by binding toβ2 adrenergic receptors(β_(2)AR)on melanocyte stem cells(McSCs).From this,NA-β_(2)AR axis could be a potential target for preventing the stress effect.However,identifying selective blockers forβ_(2)AR has been a key challenge.Therefore,in this study,advanced computer-aided drug design(CADD)techniques were harnessed to screen natural molecules,leading to the discovery of rhynchophylline as a promising compound.Rhynchophylline exhibited strong and stable binding within the active site ofβ_(2)AR,as verified by molecular docking and dynamic simulation assays.When administered to cells,rhyncho-phylline effectively inhibited NA-β_(2)AR signaling.This intervention resulted in a significant reduction of hair graying in a stress-induced mouse model,from 28.5%to 8.2%.To gain a deeper understanding of the underlying mechanisms,transcriptome sequencing was employed,which revealed that NA might disrupt melanogenesis by affecting intracellular calcium balance and promoting cell apoptosis.Importantly,rhynchophylline acted as a potent inhibitor of these downstream pathways.In conclusion,the study demonstrated that rhynchophylline has the potential to mitigate the negative impact of NA on melanogenesis by targetingβ_(2)AR,thus offering a promising solution for preventing stress-induced hair graying.

Remarkable Wear Resistance in a Complex Concentrated Alloy with Nanohierarchical Architecture and Composition Undulation

Sustained wear damages on the sliding surfaces of alloys are generally the culprit responsible for the failure of various mechanical systems.Inspired by high-entropy effects,here we deliberately deploy nanohierarchical architecture with composition undulation in a Ni50(AlNbTiV)_(50) complex concentrated alloy,which yields ultralow wear rate within the order of 10^(−7) to 10^(−6) mm^(3)/Nm between room temperature and 800℃.Such remarkable wear resistance heretofore represents one of the highest wear resistance reported for the bulk alloys or composites,and originates from the multi-type adaptive friction interface protection governed by intrinsically nano-coupled grains and nanoprecipitates.This cooperative heterostructure releases gradient frictional stress in stages upon wear at room temperature through the coexistence of multiple deformation pathways while activating a dense nanocrystalline glaze layer upon wear at 800℃ to minimize adhesive and oxidative wear.Our work uncovers a practical avenue for tailoring wear properties with multicomponent heterostructures over a wide temperature range.

MicroRNA-590-5p、microRNA-103、microRNA-34c-5p、Dicer及BRMS-1基因在肺癌中的表达研究

目的探讨microRNA-590-5p(miR-590-5p)、miR-103、miR-34c-5p、Dicer及BRMS-1在肺癌中表达及相互间关系。方法选取47例肺癌患者的癌组织及癌旁正常组织,利用Trizol提取总RNA,实时荧光定量聚合酶链反应检测基因的相对表达量。结果肺癌组织与癌旁正常组织miR-103、miR-34c-5p、Dicer及BRMS-1基因表达水平比较,差异有统计学意义(P<0.05),miR-34c-5p与P53呈正相关(P<0.05),miR-103与多药耐药相关蛋白呈正相关(P<0.05),Dicer与miR-34c-5p、miR-103及miR-590-5p呈负相关(P<0.05)。结论在肺癌组织中Dicer基因表达与miR-34c-5p呈负相关,可能通过抑制癌基因的表达,抑制肺癌的发生。

^(18)F-PBR06 PET/CT imaging of inflammation and differentiation of lung cancer in mice

The present study explored the 18-kDa translocator protein radioligand ^(18)F-PBR06 as a PET imaging biomarker for diagnosis of inflammation and compared it with ^(18)F-FDG for differentiation of inflammation and lung tumors in animals.^(18)F-PBR06 was synthesized with an average decay-corrected radiochemical yield of 30–40%(end of synthesis, EOS), and the radiochemical purity was greater than 99%. The inflammation-to-blood ratio of ^(18)FPBR06(3.53 ± 0.26) was higher than the tumor-to-blood ratio(1.77 ± 0.35)(P \ 0.001). The inflammation-tomuscle ratio of ^(18)F-PBR06(2.33 ± 0.64) was also higher than the tumor-to-muscle ratio(1.45 ± 0.14)(P = 0.036).Micro-PET/CT images showed high uptake of ^(18)F-FDG in both inflamed muscles and lung tumor tissues. However,^(18)F-PBR06 uptake in inflamed muscles remained higher than that in the lung tumor tissues, following 90 min of dynamic Micro-PET/CT imaging. Further, macrophages in the inflammatory regions showed a higher fluorescence signal than in lung tumor tissues. Results of the study confirmed that ^(18)F-PBR06 PET/CT imaging allowed for diagnosis of inflammation. Moreover,^(18)F-PBR06 uptake in the inflammatory regions was significantly higher than in lung tumor tissues, suggesting that ^(18)F-PBR06 PET/CT imaging has potential to differentiate between peripheral lung cancer and inflammation nodules.

关于三元母猪种用价值和改善措施的探讨

非洲猪瘟背景下,猪场面临两大难题,一是安全问题,二是种源问题。通过不断提升生物安全等级能够有效保障猪场安全,但种源问题却一时难以解决。在这种特殊背景下,部分猪场开始大胆创新的将三元母猪作为种源进行生产。但是,国内外关于三元母猪种用的资料文献几乎没有,无法形成有效的借鉴。一时之间,关于三元母猪究竟有没有种用价值和如何提高其种用价值成为养猪业的热门话题。文章从三元母猪种用价值、种用劣势和改善措施三个方面进行深入剖析和探讨,旨在为猪场了解和使用三元母猪提供参考。

做好窗口期应激管理来降低复产ASF感染风险

非洲猪瘟在我国的暴发引发养猪业的“大地震”,造成生猪存栏下降和猪肉供应紧张,政府采取多种措施加快复养复产,但在安全复产过程中,母猪免疫、发情、配种、分娩、断奶与转群是疫病暴发风险的关键节点,我们称其为六大风险窗口期,而应激是引发风险升高的主因。文章从应激引发黏膜损伤、应激促进巨噬细胞CD163蛋白表达、应激促进粒细胞趋化因子分泌引发血细胞的凝集以及应激抑制干扰素产生促进免疫抑制(逃避)等方面阐述风险窗口期应激与非洲猪瘟感染风险的相关性,提出了安全复产过程中需要做好风险窗口期应激管理才能有效减少非洲猪瘟感染风险的管理思路,提高复产成功率。

浅谈非洲猪瘟背景下的后备母猪初配标准和改善措施

非洲猪瘟进入我国已2年有余,目前全国生猪产能已经恢复到非瘟发生前的88%以上。但是,猪场在快速恢复产能过程中诸多问题会对猪场生产成绩造成持续影响,例如如何确立后备母猪初配标准,亟待建立和规范。文章从后备母猪初配标准的重要性、关键指标和改善措施3个方面进行深入剖析和探讨,旨在为猪场建立最佳的后备母猪初配条件提供参考。

养猪生产中“肺肠同制”理论与替抗实践

在“禁抗”的大背景下,人们必须改变与病原微生物打交道的策略,从以往通过抗生素的“打打杀杀”到“和谐共处”。文章根据中医传统“肺与大肠相表里”理论,探索替抗的“肺肠同制”技术路径,并阐明只有替抗产品与替抗管理同时进行,才能够真正实现使用“替抗”方法与抗生素使用时达到同样、乃至更好的效果。

A comparative analysis of seismic response of shallow buried underground structure under incident P,SV and Rayleigh waves

In this study,A time-domain seismic response analysis method and a calculation model of the underground structure that can realize the input of seismic P,SV and Rayleigh waves are established,based on the viscoelastic artificial boundary elements and the boundary substructure method for seismic wave input.After verifying the calculation accuracy,a comparative study on seismic response of a shallow-buried,double-deck,double-span subway station structure under incident P,SV and Rayleigh waves is conducted.The research results show that there are certain differences in the cross-sectional internal force distribution characteristics of underground structures under different types of seismic waves.The research results show that there are certain differences in the internal force distribution characteristics of underground structures under different types of seismic waves.At the bottom of the side wall,the top and bottom of the center pillar of the underground structure,the section bending moments of the underground structure under the incidences of SV wave and Rayleigh wave are relatively close,and are significantly larger than the calculation result under the incidence of P wave.At the center of the side wall and the top floor of the structure,the peak value of the cross-sectional internal force under the incident Rayleigh wave is larger than the calculation result under SV wave.In addition,the floor of the underground structure under Rayleigh waves vibrates in both the horizontal and vertical directions,and the magnification effect in the vertical direction is more significant.Considering that the current seismic research of underground structures mainly considers the effect of body waves such as the shear waves,sufficient attention should be paid to the incidence of Rayleigh waves in the future seismic design of shallow underground structures.

A Novel Current Sensor Technique for Brushless DC Motor Drives

The torque output in a permanent magnet brushless DC motor (BLDCM) is usually controlled by regulating the motor phase currents. In this paper, three kinds of PWM strategies together with some critical review on traditional current measurements in a BLDCM drive system are discussed. A novel method for assessing the PWM information and measuring the motor phase currents by a dc link current sensor is proposed. An attractive feature of the proposed method is the simplicity with the current sample processing because there is no need to incorporate the conduction information of the power switches or diodes. Only the single sided PWM or the double sided complementary PWM is needed with the proposed technique.

Embryotoxicity and Teratogenicity of Rhein

To study the effect ofrhein on embryo development of rats and fetuscs, the SD rats were divided into rhein （87.5, 175 and 350 mg/kg） group and negative control group treated with 0.5% CMC （carboxyl methyl cellulose）. The rats were administrated with rhein daily for 10 days from 6th to 15th day after pregnancy. The pregnancy rats were dissected at 20th day after pregnancy. The total weight of the fetuses, the number of corpus luteum, plant gland, absorbed fetus, live fetus, dead futus, monsters, body weight, body height and tail length were recorded. Compared with the control group, rhein group occurred with the administration of toxicity-related clinical symptoms. The changes in weight increase related with the amount ofrhein （P 〈 0.05） and the increased number of absorbed fetuses in each rhein group （P 〈 0.05） were presented. Obvious differences occurred in the rhein groups in terms of the incidence of visceral abnormalities, each organ abnormalities and fossa malformations, etc. （P 〈 0.05）. Compared with the control group, there was no significant difference in the low-dose group by fetal rat bone examination （P 〉 0.05）, while the remaining dose groups manifested various bone deformities such as sternum sections missing, incomplete ossification of the skull and thoracic vertebrae separation or deformation, which was obviously different from the control group （P 〈 0.01）. Rhein had a significant effect on the reproductive function of pregnant rats. It can even result in the bones＇ and internal organs＇ dysplasia of fetal rats. Rhein has a significant teratogenic effect in rats.

The efficacy of Baduanjin combined rehabilitation therapy on stroke patients:A Meta-analysis

Objective:To determine the effect of Baduanjin combined rehabilitation therapy on stroke patients through systematic review and Meta-analysis.Method:computer retrieval Embase and PubMed,Cochrane Library,Clonal,MBJ Journals,CNKI,Web of Science,China resources pool,Weipu Chinese science and technology journal(VIP),service system of Chinese biomedical literature database(CBM),a database of ten thousand Chinese and English in about Baduanjin to the rehabilitation effect of patients with cerebral apoplexy randomized controlled experiment(RCT),are built from library retrieval time until 31 December 2020.Two researchers independently screened the literature,extracted the data,and evaluated the risk of bias in the included studies.RevMan5.3 software and Pedro scale were used to conduct literature quality evaluation and statistical analysis of the study data.For indicators with significant heterogeneity,the heterogeneity was reduced by excluding some literature deviating from the forest map,and then the pooled analysis was performed.Meanwhile,funnel plots were drawn to analyze the publication bias of the included studies.Results:(1)A total of 114 literatures were obtained,and 27 studies,including 23 Chinese literatures and 4 English literatures,with a total of 2526 patients,were obtained after eliminating duplicates and those failing to meet the inclusion criteria.There were 12 outcome indicators involved.(2)Quality evaluation showed that 23 literatures were grade A,4 literatures were grade B,16 literatures used simple random method,4 literatures used random number table method,and 4 literatures used hidden blind assignment method.No selective reporting was found in all the included literatures.(3)Meta-analysis results show that the daily life activities ability(MD=10.10,95%CI:8.75-11.45,P<0.00001),treatment effectiveness(RR=1.1,95%CI:0.99-1.23,P=0.07),depression(SMD=1.34,95%CI:2.59-0.08,P=0.04),(BBS MD=8.58,95%CI:4.97-12.2,P<0.00001),defecate integral(MD=0.65,95%CI:0.92-0.38,P<0.00001),mental health(SMD=0.34,95%CI:1.6-0.93,P=0.6),a balance(MD=6.09,95%CI:5.76-6.43,P<0.00001),the ability to walk(MD=0.7,95%CI:0.43-0.97,P<0.00001),lower limb FMA(MD=5.69,95%CI:4.66-6.72,P<0.00001),upper limb FMA(MD=3.42,95%CI:1.53-5.3,P<0.00004).SF-36(SMD=0.65,95%CI:0.91-2.21,P=0.41),and BERG(MD=10.43,95%CI:9.02-11.48,P<0.00001),the onset of FMA contrast(MD=4.77,95%CI:3.45-6.1,P<0.00001).Conclusion:Baduanjin movement as a method of auxiliary and security can help stroke patients get the best curative effect,through the evidence-based analysis can be concluded that the Baduanjin combined rehabilitation therapy for cerebral apoplexy patients postoperative balance function,improved degree of depression,integral,defecate daily life activities ability and psychological health are greatly improved,and can significantly improve the quality of life of patients with clinically and promote patients recover.

Catalytic conversion of mixed polyolefins under mild atmospheric pressure

The chemical recycling of polyolefin presents a considerable challenge,especially as upcycling methods struggle with the reality that plastic wastes typically consist of mixtures of polyethylene(PE),polystyrene(PS),and polypropylene(PP).We report a catalytic aerobic oxidative approach for polyolefins upcycling with the corresponding carboxylic acids as the product.This method encompasses three key innovations.First,it operates under atmospheric pressure and mild conditions,using O_(2) or air as the oxidant.Second,it is compatible with high-density polyethylene,low-density polyethylene,PS,PP,and their blends.Third,it uses an economical and recoverable metal catalyst.It has been demonstrated that this approach can efficiently degrade mixed wastes of plastic bags,bottles,masks,and foam boxes.

Natural biopolymers derived hydrogels with injectable,self-healing,and tissue adhesive abilities for wound healing

Developing a biocompatible and multifunctional adhesive hydrogel with injectability and self-healing ability for promoting wound healing is highly anticipated in various clinical applications.In this paper,we present a novel natural biopolymer-derived hydrogel based on the aldehyde-modified oxidized guar gum(OGG)and the carboxymethyl chitosan(CMCS)for efficiently improving wound healing with the encapsulation of vascular endothelial growth factor(VEGF).As the hydrogels are synthesized via the dynamically reversible Schiff base linkages,it is imparted with excellent self-healing ability and good shear thinning behavior,which make the hydrogel be easily and conveniently injected through a needle.Besides,the physiochemical properties,including porous structure,mechanical strength and swelling ratio of the hydrogel can be well controlled by regulating the concentrations of the OGG.Moreover,the hydrogel can attain strong adhesion to the tissues at physiological temperature based on the Schiff base between the aldehyde group on the hydrogel and the amino group on the tissue.Based on these features,we have demonstrated that the VEGF encapsulated hydrogel can adhere tightly to the defect tissue and improve wound repair in the rat model of defected skin by promoting cell proliferation,angiogenesis,and collagen secretion.These results indicate that the multifunctional hydrogel is with great scientific significance and broad clinical application prospects.

Interaction-induced topological transition in spin-orbit coupled ultracold bosons

Recent experiments in ultracold atoms have reported the realization of quantum anomalous Hall phases in spin-orbit coupled systems.Motivated by such advances,we investigate spin-orbit coupled Bose-Bose mixtures in a two-dimensional square optical Raman lattice.Complete phase diagrams are obtained via a nonperturbative real-space bosonic dynamical mean-field theory.Various quantum phases are predicted,including Mott phases with z-ferromagnetic,xy-antiferromagnetic and vortex textures,and superfluid phases with the exotic spin orders,induced by the competition between the lattice hopping and spin-orbit coupling.To explain the underlying physics in the Mott regime,an efective Hamiltonian is derived based on second-order perturbation theory,where pseudospin order stems from the interplay of efective Dzyaloshinskii-Moriya superexchange and Heisenberg interactions.In the presence of the Zeeman field,the competition of strong interaction and Zeeman energy facilitates a topological phase,which is confirmed both by the nontrivial topological Bott index and spectral function with topological edge states.Our work indicates that spin-orbit coupling can induce rich non-Abelian topological physics in strongly correlated ultracold atomic systems.

A(CrFeNi)_(83)(AlTi)_(17) high-entropy alloy matrix solid-lubricating composite with exceptional tribological properties over a wide temperature range

High-entropy alloy matrix solid-lubricating composites(HSLCs)are promising anti-wear and friction-reduced materials to meet the demands of complicated engineering applications.Here we present a strat-egy to develop HSLCs by using the coupled high-entropy phases of(BCC+FCC+L2_(1))with near-equal volume fraction as the matrix material,instead of using the usual single phase-dominated high-entropy phases,which can preserve the intrinsic strength and deformability of the matrix while activating adap-tive wear protection during sliding.This enables a low coefficient of frictions of 0.23-0.31 and wear rates within the order of 10^(-6)-10^(-5) mm^(3) N m^(-1) for the(CrFeNi)_(83)(AlTi)_(17)-Ag-BaF_(2)/CaF_(2) HSLC between room-temperature and 800℃,considerably outperforming the reported HSLCs and conventional alloy matrix solid-lubricating composites.At low and moderate temperatures,the synergistic Ag-BaF_(2)/CaF_(2) lubricat-ing films eliminate the surface stress concentration upon wear,thus suppressing three-body abrasion and surface roughening during the groove multiplication process.At elevated temperatures,the high-entropy composite tribo-layers provide the friction interface with strong and deformable stress shielding,which avoids the oxidative and adhesive wear triggered by the delamination of the tribo-layer.Developing sim-ilar coupled high-entropy matrix phases may open an avenue for further optimization of the tribological properties of the HSLCs.

Nitrogenation of Amides via C–C and C–N Bond Cleavage

Amides are among the fundamental chemicals in organic chemistry.Compared to other carbonyl functional groups,the transformation of amide is relatively difficult and remains a challenge.The traditional deconstruction transformations of amides to other functional products are usually limited to twisted or electronically activated amides.Herein,we describe a direct nitrogenation approach to convert amides into nitriles.This chemistry provides a novel amide transformation pathway via both C–C and C–N bond cleavage.Interestingly,the simple,readily available,and inexpensive inorganic salt NaNO2 is successfully employed as a nitrogen source in this organic N-incorporation process.Applications of this study are demonstrated through the latestage modification of drug and natural product derivatives.