Photosynthesis, chilling acclimation and the response of antioxidant enzymes to chilling stress in mulberry seedlings

This study investigates the effects of cold-acclimation in conferring chilling tolerance in seedlings of the mulberry(Morus alba) variety ‘Qiuyu’. Changes in photosynthesis and antioxidant enzymes in chilling acclimatized(CA), and non-acclimatized(NA) seedlings were recorded during chilling stress(3 °C) and a recovery period(25 °C) each for 3 days. The results showed that CA plants had higher net photosynthetic rates(P_n), stomatal conductance(G_s), and maximum photochemical efficiency of photosystem Ⅱ(F_v/F_m) in response to chilling stress compared to NA. The seedlings maintained the same trends during the recovery stage. The responses of Q_A reduction degree (1-q_P) and prime electronic transfer rates(F_o) were lower in acclimatized than in non-acclimatized seedlings. Low-temperature acclimation and chilling stress also caused an increase in leaf proline and soluble sugar contents. Leaf malondialdehyde levels were significantly lower while ascorbate peroxidase(APX) activity was significantly higher in acclimatized seedlings, suggesting that elevated osmolytes and APX confer resistance to chilling temperatures. In this study on the response of mulberry seedlings to chilling stress, we also looked at the recovery process. The response to chilling determines whether mulberry leaves can survive under cold temperatures, while the recovery process determines whether photosynthesis can recover as soon as possible to avoid any secondary damage.

Iron-doxorubicin prodrug loaded liposome nanogenerator programs multimodal ferroptosis for efficient cancer therapy

Ferroptosis is a new mode of cell death,which can be induced by Fenton reactionmediated lipid peroxidation.However,the insufficient H2O2 and high GSH in tumor cells restrict the efficiency of Fenton reaction-dependent ferroptosis.Herein,a self-supplying lipid peroxide nanoreactor was developed to co-delivery of doxorubicin(DOX),iron and unsaturated lipid for efficient ferroptosis.By leveraging the coordination effect between DOX and Fe3+,trisulfide bond-bridged DOX dimeric prodrug was actively loaded into the core of the unsaturated lipids-rich liposome via iron ion gradient method.First,Fe3+could react with the overexpressed GSH in tumor cells,inducing the GSH depletion and Fe2+generation.Second,the cleavage of trisulfide bond could also consume GSH,and the released DOX induces the generation of H2O2,which would react with the generated Fe2+in step one to induce efficient Fenton reaction-dependent ferroptosis.Third,the formed Fe3+/Fe2+couple could directly catalyze peroxidation of unsaturated lipids to boost Fenton reaction-independent ferroptosis.This iron-prodrug liposome nanoreactor precisely programs multimodal ferroptosis by integrating GSH depletion,ROS generation and lipid peroxidation,providing new sights for efficient cancer therapy.

An improved gravity method to horizontal tectonic stresses and its applications in Tibet

It is significant for identifying mass movement patterns to invert horizontal tectonic stresses at different depths underneath Tibet.In recent years,a large number of achievements focusing on two-dimensional tectonic stresses have been obtained from gravity data.However,three-dimensional tectonic stresses in Tibet are still unknown or debatable.Therefore,in the present study an improved method to multilayer horizontal tectonic stresses using gravity observations is developed.The inverted multilayer horizontal tectonic stresses are in agreement with those from previous studies.In addition,rich tectonic structure and development can be revealed from the inverted multilayer horizontal tectonic stresses:(1)the distribution of horizontal tectonic stresses at various depths shows strong correlation with that of the tectonic elements,where major faults and earthquake epicenters are corresponding with stress highs and the stable basins are consistent with stress lows.(2)the mass movement patterns of whole Tibet present clockwise,and the material movement directions in the west and east are approximately southnorth and east-west,respectively.(3)in eastern Tibet,the eastward materials caused by the south-north extrusion between Indian and Eurasian plates are divided into two parts by the stable Sichuan Block,one flowing nearly southeast and the other moving almost northeast.The inverted multilayer horizontal tectonic stresses may provide direct evidences for mass movement patterns in Tibet.

Increase of nitrogen to promote growth of poplar seedlings and enhance photosynthesis under NaCl stress

The solution culture method was used to study the effect of increasing nitrogen on the growth and pho-tosynthesis of poplar seedlings under 100 mmol L-1 NaCl stress. I Increase in nitrogen reduced stomatal limitation of leaves under NaCl stress, improved utilization of CO2 by mesophyll cells, enhanced photosynthetic carbon assimi-lation capacity, significantly alleviated saline damage of NaCl, and promoted the accumulation of aboveground and root biomass. I Increased nitrogen enhanced photochemical efficiency (ΦPSⅡ) and electron transport rates, relieved the reduction of maximum photochemical efficiency (Fv/Fm) under NaCl, and reduced the degree of photoinhibition caused by NaCl stress. Increased nitrogen applications reduced the proportion of energy dissipating in the form of ineffective heat energy and hence a greater proportion of light energy absorbed by leaves was allocated to photo-chemical reactions. Under treatment with increased nitro-gen, the synergistic effect of heat dissipation and the xanthophyll cycle in the leaves effectively protected pho-tosynthetic PSⅡ and enhanced light energy utilization of leaves under NaCl stress. The increased nitrogen promoted photosynthetic electron supply and transport ability under NaCl stress evident in enhanced functioning of the oxygen-evolving complex on the electron donor side of PS Ⅱ. It increased the ability of the receptor pool to accept electrons on the PSII electron acceptor side and improved the sta-bility of thylakoid membranes under NaCl stress. Therefore, increasing nitrogen applications under NaCl stress can promote poplar growth by improving the effi-ciency of light energy utilization.

The Spin Transition and Susceptibility of NMR Samples in a Time Dependent Longitudinal Field

To construct pulsed high magnet, with rapid adjustments to large changes in the field strength, it is a mandatory acces-sory to development a special NMR probes to provide a precise real-time map of the magnetic field. In order to do so, it is necessary to understand the variations of the spin transition and susceptibility of NMR samples in a time dependent longitudinal field. This work analyzes the effect on the spin transition by a time dependent longitudinal field. For a 1/2 spin system, we have derived a simple formula for the prediction of the probabilities of occupation of the 1/2 and ?1/2 states in a non-static field. We also calculate the magnetic susceptibility of the water and give an analysis of the effect on the magnetic susceptibility in a time dependent longitudinal field and RF frequency.

Application and Popularization of New Green Prevention and Control Technology for Greenhouse Vegetables in Shouguang City,Shandong Province

In recent years,through financial subsidies,Shouguang City has promoted the application of electrostatic sprayer,dual-purpose fog and mist sprinkler machine,Bacillus cereus,flame disinfection service based on fine rotary tillage and multi-functional plant protection machine and other new green prevention and control products and technologies for the greenhouse vegetable in the city. As a result,the utilization rate of pesticides was increased by more than 5%,and the application rate was reduced by more than 10%.

丁基橡胶/聚异丁烯交联体系的黏弹行为

选用聚异丁烯-异戊二烯共聚物橡胶(IIR)和聚异丁烯(PIB)为原材料,研究了PIB含量与相对分子质量、IIR中异戊二烯含量和交联剂含量对IIR/PIB交联体系黏弹行为的影响。研究结果显示,完全交联的IIR体系几乎不发生应力松弛;添加不可交联的PIB显著降低了IIR交联后的模量,PIB相对分子质量越高,对模量的影响越小;IIR中异戊二烯含量和交联剂含量增加会使交联速率和交联密度提高,其中异戊二烯含量越高,交联剂含量变化对交联IIR/PIB黏弹性的影响越大。PIB质量分数为50%时,IIR/PIB体系损耗模量(G′′)在交联过程中的变化与交联密度、PIB性质密切相关:交联反应初期,G′′随弹性模量(G′)的提高而下降,交联反应后期则随着交联密度的上升而增加,且低分子量PIB和高分子量PIB体系的G′′值分别在G′=120~150 kPa和220~270 kPa时出现最低值;G′′~G′曲线在高交联密度下逐渐实现归一化,揭示了非交联分子链在交联IIR网络中的松弛行为。同时,PIB在交联IIR网络中松弛导致聚合物体系模量降低,但其归一化G(t)~t曲线几乎完全重合。

丁基橡胶/聚异丁烯交联网络松弛行为与力学性能

选用丁基橡胶(IIR)和聚异丁烯(PIB)为原材料,研究了PIB含量和相对分子质量、交联剂含量和IIR中异戊二烯(IP)双键含量对交联IIR/PIB复合体系力学性能的影响。结果发现,在交联IIR网络中,非交联的PIB降低了IIR的交联密度和定伸应力,但应变硬化程度和拉伸强度提高,当IIR-H和PIB-H比例为1:1时,其拉伸强度达到3.5 MPa,比纯IIR-H提高60%以上。由应变硬化参数(EH)对断裂伸长率关系可知,EH随断裂伸长率增加先增加后降低,在350%时达到最大值。通过非相似滑移管模型对应力应变曲线进行分析,获得了交联和缠结作用分别对拉伸应力的贡献(Gx和Ge),对比聚合物在高温下的动态模量(G′,G′′和G*)可知,在PIB-H质量分数不超过10%时,(G^(2)_(x)+G^(2)_(e))1/2随着G*降低变化不大;而PIB质量分数不低于30%时,G*与(G^(2)_(x)+G^(2)_(e))1/2基本呈线性关系;Gx随G′增加而增加,而Ge随G′′增加先增加后下降。

线上线下混合式-六环节实验教学实践与探索——以化学生物学实验“基于生物正交反应的蛋白质标记”为例

化学生物学综合实验是针对化学生物学专业高年级本科生开设的一门衔接本科-硕士教学的综合性实验课程。本文以“基于生物正交反应的蛋白质标记”科研融合型实验为例,结合化学生物学学科特点,将实验教学内容模块化,探索设计线上线下混合式-六环节教学方式,应用于本科生综合实验教学。经实践取得良好的教学效果,为综合型实验课程教学提供了参考与借鉴。

X-ray irradiation selectively kills thymocytes of different stages and impairs the maturation of donor-derived CD4^+CD8^+ thymocytes in recipient thymus

The aim of the present study was to determine whether the sensitivity of thymocytes to X-ray radiation depends on their proliferative states and whether radiation impairs the maturation of donor-derived thymocytes in recipient thymus.We assigned 8-week-old C57BL/6J mice into three treatment groups：1） untreated;2） X-ray radiation;3） X-ray radiation plus bone marrow transplantation with donor bone marrow cells from transgenic mice express-ing enhanced green fluorescent protein（GFP） on a universal promoter.After 4 weeks,the size of the thymus,the number and proliferation of thymocytes and ratios of different stage thymocytes were analyzed by immunohisto-chemistry and flow cytometry.The results showed that：1） CD4＋CD8＋ thymocytes were more sensitive to X-ray radiation-induced cell death than other thymocytes;2） the proliferative capacity of CD4＋CD8＋ thymocytes was higher than that of other thymocytes;3） the size of the thymus,the number of thymocytes and ratios of thymo-cytes of different stages in irradiated mice recovered to the normal level of untreated mice by bone marrow trans-plantation;4） the ratio of GFP-positive CD4＋CD8＋ thymocytes increased significantly,whereas the ratio of GFP-positive CD4＋ or CD8＋ thymocytes decreased significantly.These results indicate that the degree of sensitivity of thymocytes to X-ray radiation depends on their proliferative states and radiation impairs the maturation of donor-derived CD4＋CD8＋ thymocytes in recipient thymus.

Recent advances in cathodes for all-solid-state lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have been regarded as the candidate for the next-generation energy storage system due to the high theoretical specific capacity(1675 m Ah/g), energy density(2600 Wh/kg)and the abundance of elemental sulfur, but the application of Li-S batteries is impeded by a series of problems. Recently, all-solid-state Li-S batteries(ASSLSBs) have drawn great attention because many drawbacks such as safety issues caused by metallic lithium anodes and organic liquid electrolytes can be overcome through the use of solid-state electrolytes(SEs). However, not only the problems brought by sulfur cathodes still exist, but more trouble arouses from the interfaces between SEs and cathodes, hampering the practical application of ASSLSBs. Therefore, in order to deal with the problems, enormous endeavors have been done on ASSLSB cathodes during the past few decades, including engineering of cathode active materials, cathode host materials, cathode binder materials and cathode structures. In this review, the electrochemical mechanism and existing problems of ASSLSBs are briefly introduced. Subsequently, the strategies for developing cathode materials and designing cathode structures are presented. Then there follows a brief discussion of SE problems and expectations, and finally, the challenges and perspectives of ASSLSBs are summarized.

Ultrasound-responsive spherical nucleic acid against c-Myc/PD-L1 to enhance anti-tumoral macrophages in triple-negative breast cancer progression

Triple-negative breast cancer(TNBC)is the most challenging breast cancer subtype because of its aggressive behavior and limited therapeutic targets.c-Myc is hyperactivated in the majority of TNBC tissues,however,it has been considered an“undruggable”target due to its disordered structure.Herein,we developed an ultrasound-responsive spherical nucleic acid(SNA)against c-Myc and PD-L1 in TNBC.It is a self-assembled and carrier-free system composed of a hydrophilic small-interfering RNA(si RNA)shell and a hydrophobic core made of a peptide nucleic acid(PNA)-based antisense oligonucleotide(ASO)and a sonosensitizer.We accomplished significant enrichment in the tumor by enhanced permeability and retention(EPR)effect,the controllable release of effective elements by ultrasound activation,and the combination of targeted therapy,immunotherapy and physiotherapy.Our study demonstrated significant anti-tumoral effects in vitro and in vivo.Mass cytometry showed an invigorated tumor microenvironment(TME)characterized by a significant alteration in the composition of tumor-associated macrophages(TAM)and decreased proportion of PD-1-positive(PD-1+)T effector cells after appropriate treatment of the ultrasound-responsive SNA(USNA).Further experiments verified that tumor-conditioned macrophages residing in the TME were transformed into the anti-tumoral population.Our finding offers a novel therapeutic strategy against the“undruggable”c-Myc,develops a new targeted therapy for c-Myc/PD-L1 and provides a treatment option for the TNBC.

Remote loading paclitaxel-doxorubicin prodrug into liposomes for cancer combination therapy

The combination of paclitaxel(PTX)and doxorubicin(DOX)has been widely used in the clinic.However,it remains unsatisfied due to the generation of severe toxicity.Previously,we have successfully synthesized a prodrug PTX-S-DOX(PSD).The prodrug displayed comparable in vitro cytotoxicity compared with the mixture of free PTX and DOX.Thus,we speculated that it could be promising to improve the anti-cancer effect and reduce adverse effects by improving the pharmacokinetics behavior of PSD and enhancing tumor accumulation.Due to the fact that copper ions(Cu2+)could coordinate with the anthracene nucleus of DOX,we speculate that the prodrug PSD could be actively loaded into liposomes by Cu2+gradient.Hence,we designed a remote loading liposomal formulation of PSD(PSD LPs)for combination chemotherapy.The prepared PSD LPs displayed extended blood circulation,improved tumor accumulation,and more significant anti-tumor efficacy compared with PSD NPs.Furthermore,PSD LPs exhibited reduced cardiotoxicity and kidney damage compared with the physical mixture of Taxol and Doxil,indicating better safety.Therefore,this novel nano-platform provides a strategy to deliver doxorubicin with other poorly soluble antineoplastic drugs for combination therapy with high efficacy and low toxicity.

A facile and universal method to achieve liposomal remote loading of non-ionizable drugs with outstanding safety profiles and therapeutic effect

Liposomes have made remarkable achievements as drug delivery vehicles in the clinic.Liposomal products mostly benefited from remote drug loading techniques that succeeded in amphipathic and/or ionizable drugs,but seemed impracticable for nonionizable and poorly water-soluble therapeutic agents,thereby impeding extensive promising drugs to hitchhike liposomal vehicles for disease therapy.In this study,a series of weak acid drug derivatives were designed by a simplistic one step synthesis,which could be remotely loaded into liposomes by p H gradient method.Cabazitaxel(CTX)weak acid derivatives were selected to evaluate regarding its safety profiles,pharmacodynamics,and pharmacokinetics.CTX weak acid derivative liposomes were superior to Jevtanaa in terms of safety profiles,including systemic toxicity,hematological toxicity,and potential central nerve toxicity.Specifically,it was demonstrated that liposomes had capacity to weaken potential toxicity of CTX on cortex and hippocampus neurons.Significant advantages of CTX weak acid derivative-loaded liposomes were achieved in prostate cancer and metastatic cancer therapy resulting from higher safety and elevated tolerated doses.

受电动牙刷启发的微流控技术制备液态金属液滴构筑柔性电子器件

21世纪以来,电子产品在多个方面经历了重大突破,如小型化、物联网、柔性电子、人工智能、增强现实、虚拟现实和神经形态计算等[1].其中,柔性电子具有与人体融合的巨大潜力,吸引了研究者们的广泛关注.柔性电子的概念是在20世纪60年代提出的,起初服务于太阳能电池等领域.随着人们对可穿戴设备、软机器人和智能纺织品等需求的增加,柔性电子取得了快速发展.与坚硬的传统电子器件相比.

Targeted Degradation of DNA/RNA Binding Proteins via Covalent Hydrophobic Tagging

Targeted protein degradation(TPD)holds great promise for biological inquiry and therapeutic development.However,it still remains elusive to destruct DNA/RNA binding proteins(DBPs/RBPs)previously deemed undruggable.Herein,we report ligandassisted covalent hydrophobic tagging(LACHT)as a modular strategy for TPD of these difficult-totarget proteins.Guided by a noncovalent protein ligand,LACHT leverages a reactive N-acyl-N-alkyl sulfonamide group to covalently label the protein target with a hydrophobic adamantane,which further engages the cellular quality control mechanism to induce proteolytic degradation.Using a smallmolecule ligand,we demonstrated that LACHT allowed TPD of a DBP,bromodomain-containing protein 4,in human leukemia cells with high efficiency.Mechanistic studies revealed that LACHT-mediated TPD dependent on ligand-directed irreversible tagging and the covalently labeled proteins underwent polyubiquitination before removal through both the proteasome and the lysosome.Furthermore,when an RNA ligand was employed,we showed that LACHT also enabled TPD of an RBP,Lin28a,leading to upregulation of its downstream let-7 miRNA.This study thus provides a generalizable platform to expand the TPD toolbox for biomedical applications.

三江平原土壤动物群落多样性对CO_2浓度升高的响应

为研究大气CO_2浓度升高条件下土壤动物的响应,本文采用开顶式气室(OTC)控制大气CO_2浓度,设置了3个梯度,分别为低浓度370 ppm背景CO_2 (AC)、中浓度550 ppm CO_2 (EC1)和高浓度700 ppm CO_2 (EC2)。于2017年秋季取样并用改良Tullgren干漏斗法和Baermann湿漏斗分离土壤动物。结果表明:(1)共捕获土壤动物6,268头,隶属于7纲15目,优势类群为甲螨亚目,占捕获量的88.13%;常见类群为弹尾目和双翅目幼虫,合计占捕获量的9%。不同CO_2浓度水平下,优势类群(甲螨亚目)和常见类群(弹尾目、双翅目幼虫)相同,但是稀有类群存在一定差异。(2)CO_2浓度升高显著增加了甲螨亚目的类群数和个体密度,显著降低了弹尾目的类群数和个体密度,对其他土壤动物无显著影响。(3)三江平原不同浓度条件下土壤动物的Shannon-Wiener多样性指数、Pielou均匀度指数均为AC>EC1> EC2,而优势度指数为EC2> EC1> AC,丰富度指数为AC> EC2> EC1。研究表明,气候变化有可能影响土壤动物的群落结构以及土壤动物的多样性。

基于二芳基四氮唑修饰短肽的光敏超分子水凝胶

本文报道了一种可对光照响应发生降解的超分子水凝胶,成胶因子为二芳基四氮唑修饰二肽(MeO-TetGA). MeO-Tet-GA在中性缓冲溶液中可发生自组装形成超分子水凝胶,并且该水凝胶具有良好的机械性能,动态储能模量G’在500 Pa以上.基于二芳基四氮唑与末端烯烃间的分子间光点击化学反应,我们可进一步在MeO-TetGA超分子水凝胶中修饰亲水性的苯基磺酸钠从而打破水凝胶内部的亲疏水平衡,进而诱发水凝胶内部纤维结构的破坏以及水凝胶的降解.此外,我们尝试了将MeO-Tet-GA超分子水凝胶应用于小鼠乳腺癌4T1细胞的三维培养,发现MeO-Tet-GA超分子水凝胶具有优良的生物相容性,在用于细胞三维培养3 d后不会造成明显的4T1细胞死亡.综上所述,由MeO-Tet-GA形成的超分子水凝胶是一种潜在的生物材料,在细胞长期三维培养以及通过光照调节细胞微环境进而研究细胞行为变化方面具有应用前景.

Collusion and Economic Growth: A New Perspective on the China Model

In this paper,we propose a political-economy model of China that explains both the rapid economic growth and frequent rate of accidents that have occurred in China.The central government delegates authority to the local government to regulate the production activities of the firm.Under information asymmetry,the local government can collude with the firm and choose"bad"technology,the use of which will lead to faster economic growth and more accidents than the use of"good"technology.We characterize optimal equilibrium within collusion contracts,under which the central government will allow collusion when the cost to eliminate collusion is high.We also characterize the optimal collusion-proof contract,under which the payments,reprimands,and taxes that take place between the local government and the firm are endogenously determined.Our predictions on collusion and growth are supported by an empirical study on the coal industry.

A comprehensive study on the heat transfer characteristics of windward bend lattice frame structure

The windward bend lattice frame structure(WB structure)is characterized by a high heat transfer coefficient and low friction factor.The WB structure can be applied for ther-mal protection system,protecting outer walls of afterburner and nozzles from being damaged by the heating load of hot gas,for air cooling system of the power battery module,dissipating the heat generated during its charging and discharging.In this paper,the heat transfer charac-teristics of the windward bend lattice frame structure have been comprehensively studied.A systematic 3D numerical simulation has been conducted to investigate the effects of the struc-tural parameters of the WB structure,including the pitches in both flow direction and transverse direction,the diameter and the inclination angle of windward bend ligament,on its flow resis-tance and heat transfer enhancement,which has been evaluated by comparing its Nusselt num-ber under an equal pumping power.Furthermore,the contribution of an important parameter,i.e.,the ratio of the interstitial heat transfer rate to the end-wall heat transfer rate(RQ),to the overall heat transfer rate has been fully discussed.As a result,the case of 6 units in the longi-tudinal direction and 2.5 units in the transverse direction,i.e.(nx Z 6,nz Z 2.5)exhibits the best performance in the light of the value of the Nusselt number. Moreover, the structure with aratio of RQ ranges in 4.5e5.0 achieves a better heat transfer performance. Finally, two colorcontour graphs showing an optimal range of Nusselt number coordinated by unit numbers(nx, nz) for pumping powers of 2500 and 3000 have been presented. The graphs correctly reflectthe variation of Nusselt numbers of structures with different nx and nz, and the conclusionsremain consistent with the discussion in sections 4.2 and 4.3, instructing the reasonable selec-tion of structural parameters of a thermal protection system embedded with WB structure.