光镊捕获和操控尺度极限的进展

光镊技术能够实现对介观乃至微观颗粒的稳定捕获和灵活操控,是对微纳物体和单个分子施加力并观测其响应的理想操控手段。受限于光的衍射极限,传统光镊难以实现对100 nm以下物体的捕获和操控。研究者们通过开发特殊的材料和结构,将它们与传统光镊技术结合,不断突破其在小尺度物体的捕获和操控极限。本文主要综述了近年来光镊的不同技术路线在突破捕获操控极限的研究进展,以及其在物理化学领域中的应用,并对其发展和应用进行展望。

Semi-analytical solution for internal forces of tunnel lining with multiple longitudinal cracks

Longitudinal cracks on the tunnel lining significantly influence the performance of tunnels in operation.In this study,we propose a semi-analytical method that provides a simple and effective way to calculate the internal forces of tunnel linings with multiple cracks.The semi-analytical solution is obtained using structural analysis considering the flexural rigidity for the cracked longitudinal section of the tunnel lining.Then the proposed solution is verified numerically.Using the proposed method,the influences of the crack depth and the number of cracks on the bending moment and modified crack tip stress are investigated.With the increase in crack depth,the bending moment of lining scetion adjacent to the crack decreases,while the bending moment of lining scetion far away from the crack increases slightly.The more the number of cracks in a tunnel lining,the easier the new cracks initiated.

AR技术在传承与弘扬非物质文化遗产中的应用——以敦煌文化为例

近些年,元宇宙概念逐步兴起,给予传承与弘扬非物质文化遗产更多的可能性。基于AR技术的非物质文化遗产资源产业化开发成为当下的研究趋势。利用AR技术的便捷实用性和出色展现效果,推进非物质文化遗产的传承与弘扬工作迈入新阶段。该文以敦煌文化为例,研究AR技术与敦煌文化可行的结合方式,探求当下更易于接受的传统文化展现形式,力求结合多方需求,得到可实行、可接受、可传播的数字化非遗产物。

留仙洞万科云设计公社A4+B2办公室

项目位于深圳南山区大沙河创新带,科技园北区,是留仙洞总部基地九街坊规划中的北绿廊地块。设计通过大绿化坡道将首层与负一层连接,划分连续的办公单元,将北向区域高起作为独立建筑单元,增加自然采光通风洞口。在保证屋顶公共绿地的连续性与提供地下办公空间良好环境之间寻找平衡点。

Analytical algorithm for longitudinal deformation profile of a deep tunnel

To investigate the longitudinal deformation profile(LDP)of a deep tunnel in non-hydrostatic condition,an analytical model is proposed in our study.In this model,the problem is considered as a superposition of two partial models,and the displacement field of the second partial model is the same as that of the concerned problem.Therefore,the problem can be solved by a model with simple boundary conditions.We obtain the solutions for the stress and displacement fields of an infinite body caused by arbitrary surface tractions on the boundary of the coming tunnel(zone inside the tunnel before excavation)by integrating the extended Kelvin solution over the boundary.The obtained stress solution is used to solve the specific surface tractions,which can satisfy the boundary conditions of the second partial model,on the boundary of the coming tunnel in an infinite body.Then,the specific surface tractions are substituted into the obtained displacement solution to solve the displacement on the wall and face of the tunnel.Therefore,the LDP can also be calculated.The proposed solution is verified by both numerical simulation and the LDP functions recommended by other researchers.The major advantage of our analytical model is that it can consider the effects of the axial and horizontal lateral pressure coefficients.It is revealed that the horizontal lateral pressure coefficient majorly affects the LDP behind the tunnel face,while the axial lateral pressure coefficient dominates the LDP ahead of the tunnel face.Furthermore,the deformation characteristics of the LDPs ahead of the face and the unexcavated core are investigated.The axial displacements of the excavation face can be used to predict the crown displacements ahead of the face.

The role of XPC protein deficiency in tobacco smoke-induced DNA hypermethylation of tumor suppressor genes

DNA hypermethylation of tumor suppressor genes has been frequently observed in cancer patients, and therefore, may provide a valuable biomarker for cancer prevention and treatment. DNA hypermethylation may also provide an important mechanism in cancer progression. Lung cancer is strongly associated with exposure to environmental carcinogens, especially tobacco smoke. DNA damage generated by tobacco smoke is believed to play an important role in lung cancer development. XPC is a DNA damage recognition protein required for DNA repair and other DNA damage responses and attenuated XPC protein levels have been detected in many lung cancer patients. We studied the role of XPC protein deficiency in tobacco smoke-caused DNA hypermethylation of important tumor suppressor genes. Using both normal human fibroblasts (NF) and XPC-deficient hu man fibroblasts (XPC), our DNA methylation studies demonstrated that the XPC deficiency caused elevated levels of DNA hypermethylation in both Brca1 and Mlh1 tumor suppressor genes following exposure to tobacco smoke condensate (TSC). The results of our ChIP studies revealed that the XPC deficiency led to an increased binding of DNA methyltransferase 3A (DNMT3A) at the promoter region CpG island-containing sequences of these genes under the TSC treatment;however, this increase was partially diminished with prior treatment with caffeine. The results of our immuno-precipitation (IP) studies demonstrated a protein-protein interaction of the ATR with DNMT3A. Our western blots revealed that the XPC deficiency caused an increase in TSC-induced ATR phosphorylation at serine 428, an indicator of ATR activation. All these results suggest that XPC deficiency causes an accelerated DNA hypermethylation in important tumor suppressor genes under tobacco smoke exposure and activation of the ATR signaling pathway is involved in this DNA hypermethylation process.

Evidence for topological superconductivity: Topological edge states in Bi2Te3/FeTe heterostructure

Majorana fermions have been predicted to exist at the edge states of a two-dimensional topological superconductor.We fabricated single quintuple layer(QL)Bi2Te3/FeTe heterostructure with the step-flow epitaxy method and studied the topological properties of this system by using angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy.We observed the coexistence of robust superconductivity and edge states on the single QL Bi2Te3 islands which can be potential evidence for topological superconductor.

Transferrin Is Up-Regulated by Microbes and Acts as a Negative Regulator of Immunity to Induce Intestinal Immunotolerance

Cross-talks (e.g., host-driven iron withdrawal and microbial iron uptake between host gastrointestinal tract and commensal microbes) regulate immunotolerance and intestinal homeostasis. However, underlying mechanisms that regulate the cross-talks remain poorly understood. Here, we show that bacterial products up-regulate iron-transporter transferrin and transferrin acts as an immunosuppressor by interacting with cluster of differentiation 14 (CD14) to inhibit pattern recognition receptor (PRR) signaling and induce host immunotolerance. Decreased intestinal transferrin is found in germ-free mice and human patients with ulcerative colitis, which are characterized by impaired intestinal immunotolerance. Intestinal transferrin and host immunotolerance are returned to normal when germ-free mice get normal microbial commensalism, suggesting an association between microbial commensalism, transferrin, and host immunotolerance. Mouse colitis models show that transferrin shortage impairs host’s tolerogenic responses, while its supplementation promotes immunotolerance. Designed peptide blocking transferrin–CD14 interaction inhibits immunosuppressive effects of transferrin. In monkeys with idiopathic chronic diarrhea, transferrin shows comparable or even better therapeutic effects than hydrocortisone. Our findings reveal that by up-regulating host transferrin to silence PRR signaling, commensal bacteria counteract immune activation induced by themselves to shape host immunity and contribute for intestinal tolerance.

超高效液相色谱法测定食用菌中7种脂溶性维生素

采用超高效液相色谱法同时测定食用菌中VA、VD2、α-生育酚、β-生育酚、γ-生育酚、δ-生育酚、麦角甾醇共7种脂溶性维生素的含量。样品经皂化、萃取、氮吹复溶处理后,用Phenomenex Kinetex PFP(250 mm×4.6 mm,5μm)分离,以水(A)-甲醇(B)(体积比,0~15 min,15%A^5%A;15~18min,5%A;18~20 min,5%A^15%A)为流动相,柱温25℃,流速0.8m L/min,进样量10μL,检测波长VA为325 nm,VD2为264 nm,VE为294 nm,麦角甾醇为281 nm,进入紫外检测器进行检测。7种目标物在16 min内分离出峰,在各自的质量范围内线性关系良好(r=0.9999),检出限为0.001~0.01 mg/kg,定量限为0.004~0.04 mg/kg,在3个添加水平下的平均加标回收率为82.7%~101%,相对标准偏差(RSD)为0.50%~4.66%(n=3)。该方法准确、高效、结果可靠,适用于食用菌中7种脂溶性维生素的同时测定。

温度及光照对婴幼儿配方乳粉中VA、VD稳定性的影响

为研究不同温度条件下婴幼儿配方乳粉中VA和VD的稳定性,分别考察其在25、40、60 ℃及80 ℃储藏条件下乳粉中的含量变化;通过采用透光和避光2种方式储存的乳粉进行光照试验,研究了光照对乳粉中VA和VD稳定性的影响。结果表明,25 ℃储藏条件下,乳粉中VA和VD含量均无明显变化;40、60 ℃和80 ℃条件下,VA含量有不同程度的降解,而VD无明显变化。光照条件下,乳粉中VA和VD均发生明显降解,其中VA含量在光照1 h后损失达50%,VD含量在光照12 h后损失了将近50%。

Anticarin-β shows a promising antiosteosarcoma effect by specifically inhibiting CCT4 to impair proteostasis

Unlike healthy, non-transformed cells, the proteostasis network of cancer cells is taxed to produce proteins involved in tumor development. Cancer cells have a higher dependency on molecular chaperones to maintain proteostasis. The chaperonin T-complex protein ring complex(TRiC) contains eight paralogous subunits(CCT1-8), and assists the folding of as many as 10% of cytosolic proteome.TRiC is essential for the progression of some cancers, but the roles of TRiC subunits in osteosarcoma remain to be explored. Here, we show that CCT4/TRiC is significantly correlated in human osteosarcoma,and plays a critical role in osteosarcoma cell survival. We identify a compound anticarin-β that can specifically bind to and inhibit CCT4. Anticarin-β shows higher selectivity in cancer cells than in normal cells. Mechanistically, anticarin-β potently impedes CCT4-mediated STAT3 maturation. Anticarin-β displays remarkable antitumor efficacy in orthotopic and patient-derived xenograft models of osteosarcoma.Collectively, our data uncover a key role of CCT4 in osteosarcoma, and propose a promising treatment strategy for osteosarcoma by disrupting CCT4 and proteostasis.

Application of electrochemistry to single-molecule junctions: from construction to modulation

State-of-the-art molecular electronics focus on the measurement of electrical properties of materials at the single-molecule level.Experimentally, molecular electronics face two primary challenges. One challenge is the reliable construction of single-molecule junctions, and the second challenge is the arbitrary modulation of electron transport through these junctions. Over the past decades, electrochemistry has been widely adopted to meet these challenges, leading to a wealth of novel findings. This review starts from the application of electrochemical methods to the fabrication of nanogaps, which is an essential platform for the construction of single-molecule junctions. The utilization of electrochemistry for the modification of molecular junctions,including terminal groups and structural backbones, is introduced, and finally, recent progress in the electrochemical modulation of single-molecule electron transport is reviewed.