Contact radius of stamps in reversible adhesion

A mechanics model is developed for the contact radius of stamps with pyramid tips in transfer printing.This is important to the realization of reversible control of adhesion,which has many important applications,such as climbing robots,medical tapes,and transfer printing of electronics.The contact radius is shown to scale linearly with the work of adhesion between the stamp and the contacting surface,and inversely with the plane-strain modulus of the stamp. It also depends on the cone angle and tip radius of the stamp,but is essentially independent of details of the tip geometry.

Highly Stretchable Shape Memory Self-Soldering Conductive Tape with Reversible Adhesion Switched by Temperature

With practical interest in the future applications of next-generation electronic devices,it is imperative to develop new conductive interconnecting materials appropriate for modern electronic devices to replace traditional rigid solder tin and silver paste of high melting temperature or corrosive solvent requirements.Herein,we design highly stretchable shape memory self-soldering conductive(SMSC)tape with reversible adhesion switched by temperature,which is composed of silver particles encapsulated by shape memory polymer.SMSC tape has perfect shape and conductivity memory property and anti-fatigue ability even under the strain of 90%.It also exhibits an initial conductivity of 2772 S cm^(−1) and a maximum tensile strain of~100%.The maximum conductivity could be increased to 5446 S cm^(−1) by decreasing the strain to 17%.Meanwhile,SMSC tape can easily realize a heating induced reversible strong-to-weak adhe-sion transition for self-soldering circuit.The combination of stable conductivity,excellent shape memory performance,and temperature-switching reversible adhesion enables SMSC tape to serve two functions of electrode and solder simultaneously.This provides a new way for conductive interconnecting materials to meet requirements of modern electronic devices in the future.

Bioinspired Injectable Self-Healing Hydrogel Sealant with Fault-Tolerant and Repeated Thermo-Responsive Adhesion for Sutureless Post-Wound-Closure and Wound Healing

Hydrogels with multifunctionalities,including sufficient bonding strength,injectability and self-healing capacity,responsive-adhesive ability,fault-tolerant and repeated tissue adhesion,are urgently demanded for invasive wound closure and wound healing.Motivated by the adhesive mechanism of mussel and brown algae,bioinspired dynamic bonds cross-linked multifunctional hydrogel adhesive is designed based on sodium alginate(SA),gelatin(GT)and protocatechualdehyde,with ferric ions added,for sutureless post-wound-closure.The dynamic hydrogel cross-linked through Schiff base bond,catechol-Fe coordinate bond and the strong interaction between GT with temperature-dependent phase transition and SA,endows the resulting hydrogel with sufficient mechanical and adhesive strength for efficient wound closure,injectability and self-healing capacity,and repeated closure of reopened wounds.Moreover,the temperature-dependent adhesive properties endowed mispositioning hydrogel to be removed/repositioned,which is conducive for the fault-tolerant adhesion of the hydrogel adhesives during surgery.Besides,the hydrogels present good biocompatibility,near-infrared-assisted photothermal antibacterial activity,antioxidation and repeated thermo-responsive reversible adhesion and good hemostatic effect.The in vivo incision closure evaluation demonstrated their capability to promote the post-wound-closure and wound healing of the incisions,indicating that the developed reversible adhesive hydrogel dressing could serve as versatile tissue sealant.

A thermal actuated switchable dry adhesive with high reversibility for transfer printing

Transfer printing based on switchable adhesive that heterogeneously integrates materials is essential to develop novel electronic systems,such as flexible electronics and micro LED displays.Here,we report a robust design of a thermal actuated switchable dry adhesive,which features a stiff sphere embedded in a thermally responsive shape memory polymer(SMP)substrate and encapsulated by an elastomeric membrane.This construct bypasses the unfavorable micro-and nano-fabrication processes and yields an adhesion switchability of over1000 by combining the peel-rate dependent effect of the elastomeric membrane and the thermal actuation of the sub-surface embedded stiff sphere.Experimental and numerical studies reveal the underlying thermal actuated mechanism and provide insights into the design and operation of the switchable adhesive.Demonstrations of this concept in stamps for transfer printing of fragile objects,such as silicon wafers,silicon chips,and inorganic micro-LED chips,onto challenging non-adhesive surfaces illustrate its potential in heterogeneous material integration applications,such as flexible electronics manufacturing and deterministic assembly.

Laparoscopic vs open surgery in ileostomy reversal in Crohn’s disease:A retrospective study

BACKGROUND Although minimally invasive surgery is becoming more commonly applied for ileostomy reversal(IR),there have been relatively few studies of IR for patients with Crohn's disease(CD).It is therefore important to evaluate the potential benefits and risks of laparoscopy for patients with CD.AIM To compare the safety,feasibility,and short-term and long-term outcomes of laparoscopic IR(LIR)vs open IR(OIR)for the treatment of CD.METHODS The baseline characteristics,operative data,and short-term(30-d)and long-term outcomes of patients with CD who underwent LIR and OIR at our institution between January 2017 and January 2020 were retrieved from an electronic database and retrospectively reviewed.RESULTS Of the 60 patients enrolled in this study,LIR was performed for 48 and OIR for 12.There were no statistically significant differences in baseline characteristics,operation time,intraoperative blood loss,days to flatus and soft diet,postoperative complications,hospitalization time,readmission rate within 30 d,length of hospitalization,hospitalization costs,or reoperation rate after IR between the two groups.However,patients in the LIR group more frequently required lysis of adhesions as compared to those in the OIR group(87.5%vs 41.7%,respectively,P<0.05).Notably,following exclusion of patients who underwent enterectomy plus IR,OIR was more advantageous in terms of postoperative recovery of gastrointestinal function and hospitalization costs.CONCLUSION The safety and feasibility of LIR for the treatment of CD are comparable to those of OIR with no increase in intraoperative or postoperative complications.

玻璃表面化学蚀刻增强基板上类金刚石薄膜的结合力与透光率

本研究采用一种新方法来改善类金刚石(DLC)薄膜在玻璃表面结合力弱的问题。首先通过反胶束微乳液刻蚀法在玻璃表面蚀刻出致密连续的微米凹坑,然后采用磁控溅射依次镀制SiO_(2)、SiOC过渡膜及DLC膜。由于薄膜物质嵌在连续的微米凹坑里形成波浪状的3D膜层,不仅可将应用在膜上的作用力分解释放,而且也大大提高了玻璃表面与膜的接触面积,从而显著增强DLC薄膜在玻璃表面的结合。为了改善薄膜在可见光区的透光性能,镀膜前,在玻璃球形凹坑的玻璃表面进行二次化学蚀刻,在凹坑里生成纳米孔结构,减少反射,提高可见光透过率。本研究采用紫外-可见分光光度计、扫描电镜、拉曼光谱仪、纳米力学综合测试系统、显微硬度仪及铅笔硬度测试等手段对样品进行了性能表征。结果表明,SiO_(2)、SiOC过渡层可以使玻璃基板与DLC薄膜之间结合力,从(28.82±0.62)mN提高到(53.32±0.78)mN,提高近1倍。在相同的DLC膜镀制条件下,玻璃表面的微米凹坑可进一步使DLC的膜基结合力再提高1倍,从(53.32±0.78)mN提高到(106.32±0.82)mN。显微硬度从543.7 HV提高到735.5 HV,铅笔硬度从6 H提高到7 H。通过二次化学蚀刻产生的纳米孔可使镀膜玻璃的可见光平均透过率提高约4%。

可光致固液转变偶氮苯染料的合成及其光控可逆黏合性能

光控可逆胶黏剂在特定波长的光照射下可以改变其黏接性质,实现高效的黏合与分离,并可多次重复利用。试验设计合成了一种含单个偶氮苯单元的小分子化合物D-Azo,探究了其光致固液转化及光控可逆黏合性能。紫外光照射前后的紫外-可见吸收光谱、氢核磁共振谱(1H NMR)及示差热量扫描(DSC)表明,在紫外光的作用下,D-Azo分子发生了异构转变,在光诱导下染料由固态快速转化为液态,且具有良好的循环稳定性,能够在多个光照周期中保持稳定的光响应性能。将D-Azo用于光控可逆黏合,D-Azo黏接的PMMA板承重达30~35 kg,黏附强度为0.80~0.93 MPa。D-Azo分子具有明显的光致固液转化特性,紫外光照射可以使其脱黏合,表明作为胶黏剂的可逆性和重复使用性能。该材料可望在纺织复合材料黏合领域以及可穿戴黏合材料等领域获得应用。

表达外源基因SPAM1重组CAV-2溶瘤病毒的构建与拯救

旨在研究犬腺病毒-2型(canine adenovirus type 2,CAV-2)作为溶瘤病毒的潜力并进一步探索精子黏附因子(SPAM1)协同CAV-2重塑肿瘤微环境在肿瘤免疫治疗中的应用价值。本研究以P15A-CAV-2反向遗传操作平台为基础,使用RED/ET同源重组系统构建携带SPAM1外源基因的中间载体,使用中间载体将CAV-2骨架载体E3区域缺失并替换SPAM1外源基因表达盒。再利用合成引物敲除kmccdB反向筛选表达盒构建P15A-CAV-2-mCMV-SPAM1-SV40 polyA感染性克隆质粒并在MDCK-E1A细胞系中拯救重组溶瘤病毒,对重组病毒体外溶瘤效应进行验证。根据测序与酶切验证结果证明,本研究成功构建并拯救出稳定表达外源基因SPAM1的重组溶瘤病毒1株;IFA试验证明,重组毒株能够高水平稳定表达外源基因且外源蛋白具有可弥散分布于细胞间的特点。缺失E3区域表达外源基因SPAM1的重组溶瘤病毒通过光镜观察和CCK8检测发现具有对犬癌细胞系A72强烈的杀伤效应。综上,本研究成功构建1株具有良好溶瘤效应的重组CAV-2,为后续应用于宠物肿瘤治疗奠定了基础。

Robust scalable reversible strong adhesion by gecko-inspired composite design

Bio-inspired reversible adhesion has significant potential in many fields requiring flexible grasping and manipulation,such as precision manufacturing,flexible electronics,and intelligent robotics.Despite extensive efforts for adhesive synthesis with a high adhesion strength at the interface,an effective strategy to actively tune the adhesion capacity between a strong attachment and an easy detachment spanning a wide range of scales has been lagged.Herein,we report a novel soft-hard-soft sandwiched composite design to achieve a stable,repeatable,and reversible strong adhesion with an easily scalable performance for a large area ranging from~1.5 to 150 cm2 and a high load ranging from~20 to 700 N.Theoretical studies indicate that this design can enhance the uniform loading for attachment by restraining the lateral shrinkage in the natural state,while facilitate a flexible peeling for detachment by causing stress concentration in the bending state,yielding an adhesion switching ratio of~54 and a switching time of less than~0.2 s.This design is further integrated into versatile grippers,climbing robots,and human climbing grippers,demonstrating its robust scalability for a reversible strong adhesion.This biomimetic design bridges microscopic interfacial interactions with macroscopic controllable applications,providing a universal and feasible paradigm for adhesion design and control.

反渗透自粘防水卷材对高层医院建筑工程的应用研究

为了验证自粘效果提升施工效率与质量,研究环保型反渗透自粘防水卷材对高层医院建筑工程的影响。使用多种高分子材料制备主体层,树脂与粘接材料制备出粘胶层,压制主体层和粘胶层,制备出应用在高层医院建筑工程的环保型反渗透自粘防水卷材。测试该卷材不同粘接方法以及不同温度环境下的剥离强度,计算静水环境和压力水环境该卷材的反渗透性,接种菌株分析该卷材的抗霉腐性能。结果显示,上下涂覆粘胶层的卷材剥离强度更高,但是高温环境会降低剥离强度;该卷材在高压水环境会比静水环境反渗透性差,但是显著高于目前市售普通卷材。

Complex coacervate-derived hydrogel with asymmetric and reversible wet bioadhesion for preventing UV light-induced morbidities

Protecting the skin from UV light irradiation in wet and underwater environments is challenging due to the weak adhesion of existing sunscreen materials but highly desired.Herein we report a polyethyleneimine/thioctic acid/titanium dioxide(PEI/TA/TiO_(2))coacervate-derived hydrogel with robust,asymmetric,and reversible wet bioadhesion and effective UV-light-shielding ability.The PEI/TA/TiO_(2)complex coacervate can be easily obtained by mixing a PEI solution and TA/TiO_(2)powder.The fluid PEI/TA/TiO_(2)coacervate deposited on wet skin can spread into surface irregularities and subsequently transform into a hydrogel with increased cohesion,thereby establishing interdigitated contact and adhesion between the bottom surface and skin.Meanwhile,the functional groups between the skin and hydrogel can form physical interactions to further enhance bioadhesion,whereas the limited movement of amine and carboxyl groups on the top hydrogel surface leads to low adhesion.Therefore,the coacervate-derived hydrogel exhibits asymmetric adhesiveness on the bottom and top surfaces.Moreover,the PEI/TA/TiO_(2)hydrogel formed on the skin could be easily removed using a NaHCO3 aqueous solution without inflicting damage.More importantly,the PEI/TA/TiO_(2)hydrogel can function as an effective sunscreen to block UV light and prevent UV-induced MMP-9 overexpression,inflammation,and DNA damage in animal skin.The advantages of PEI/TA/TiO_(2)coacervate-derived hydrogels include robust,asymmetric,and reversible wet bioadhesion,effective UV light-shielding ability,excellent biocompatibility,and easy preparation and usage,making them a promising bioadhesive to protect the skin from UV light-associated damage in wet and underwater environments.

A strong and reversible adhesive fibrillar surface based on an advanced composite with high strength and strong adhesion

A material-structure integrated design method is proposed in this paper,with which micropillar and microwedge arrayed surfaces are fabricated based on a novel nanoparticlereinforced silicone rubber composite(NRSRC)with high mechanical strength and strong surface adhesion.It is found that the micropillar-arrayed surface and the microwedgearrayed surface show a normal adhesive strength of 50.9 kPa and a shear adhesive strength of 137.3 kPa,respectively,which are much higher than those of previously reported adhesive surfaces made by pure soft polymers.Furthermore,the micro-wedgearrayed surface shows not only strong and stable adhe-sion on rough and smooth substrates but also an obvious anisotropy in the adhesion property.The latter consequently leads to an easy control of the attachment/detachment switch,which is evidenced by a mechanical gripper with a microwedged surface.Therefore,firmly picking up and easily releasing a heavy glass plate can be realized.All these results demonstrate the apparent advantages of the present compo-sitebased fibrillar surfaces in achieving reliable and reversible adhesion and should have promising applications for manufac-turing advanced adhesive devices,such as mechanical fixtures,portable climbing equipment and space robots.

富水环境下引水隧洞二次衬砌防水技术创新

富水隧洞施工过程中的防水施工技术很大程度上决定了隧洞建设项目的效果,如果施工中出现二衬混凝土脱落、裂缝,或者止水带平直度很差,都会导致隧洞渗漏水,为工程运行带来不利影响。本文结合吉林中部城市引松供水工程隧洞施工实例,分析了二次衬砌拱部纵向退管带模注浆工艺、自粘反粘式防水板、新型止水带夹具等新工艺、新技术在解决隧洞二衬裂缝、渗水、漏水、脱空、止水带平直度差等常见工程问题上的作用。

低分子姬松茸多糖对荷瘤小鼠肿瘤组织CD44 mRNA表达的影响

目的:观察低分子姬松茸多糖(Low Molecular Weight Polysaccharide Isolated from Agaricus blazei Murill,LM-PAB)对荷瘤小鼠肿瘤组织中CD44 mRNA表达的影响。方法:BALB/c小鼠右侧腋窝皮下接种S180肉瘤,腹腔注射50、100和200 mg/(kg.d)LMPAB,连续7天。给药结束后24h取肿瘤组织,实时定量RT-PCR法检测肿瘤组织CD44 mR-NA表达水平。结果:与模型对照组比较,LMPAB各剂量组50、100和200mg/(kg.d))CD44 mRNAΔCt显著升高(P<0.01),表明CD44 mRNA表达下调,并呈剂量依赖性。结论:LMPAB可能通过降低CD44 mRNA的表达,抑制了流动的肿瘤细胞与内皮细胞的黏附,从而减少肿瘤转移。

环保型丙烯酸系热熔压敏胶粘剂

用本体聚合法合成了含有软单体、硬单体和官能单体的丙烯酸酯类热熔压敏胶 。

混凝-反渗透组合工艺处理丙烯酸酯胶粘剂工业废水

以硫酸铝为破乳剂、阳离子型PAM(聚丙烯酰胺)为絮凝剂,采用混凝法对强碱性水性丙烯酸酯胶粘剂工业废水[COD(化学需氧量)为37.90 g/L,pH值为13.1]进行预处理,然后运用反渗透技术对预处理后的废水进行深度处理。考察了破乳剂、絮凝剂以及搅拌时间等对废水预处理效果的影响,同时确定了混凝-反渗透组合工艺的最佳工艺参数。结果表明:常温破乳剂的最佳投料量为28.2 mg/L,絮凝剂最佳投料量为0.24 g/mL,最佳搅拌时间为10 min,反渗透操作温度为30℃、操作压力为0.4 MPa;该工业废水经混凝-反渗透组合工艺处理后,其COD值降至0.069 g/L、COD去除率达99.8%。

爱立敷泡沫敷料反向粘贴法在预防无创呼吸机所致鼻面部压力性损伤中的应用研究

目的探讨爱立敷泡沫敷料反向粘贴法在预防无创呼吸机所致鼻面部压力性损伤中的应用。方法选取2015年1月-2017年12月我院收治使用无创呼吸机治疗的60例患者为对照组,敷料去除被贴纸,轻粘于患者面部;另选取2017年7月-2018年12月收治使用无创呼吸机治疗的59例患者为观察组,敷料去除被贴纸,其自粘面向上反向粘贴于面罩上。对比两组患者鼻面部压力性损伤发生率及患者舒适度。结果观察组压力性损伤发生率为1.69%,对照组压力性损伤发生率为11.67%,两组差异有统计学意义(P<0.05);观察组患者舒适度为96.61%,对照组患者舒适度为83.33%,观察组舒适度高于对照组,差异有统计学意义(P<0.05)。结论爱立敷泡沫敷料反向粘贴法在预防无创呼吸机所致鼻面部压力性损伤中效果显著,且可提高患者舒适度,值得推广使用。

形状记忆聚合物表面水下油黏附性的可逆调控

采用模板法在形状记忆聚合物表面获得一种具有形状记忆特征的表面微结构,在氧等离子作用下,表面呈现低黏附的水下超疏油特性.在外压作用下,表面微结构发生坍塌,失去水下超疏油性,同时表面对油滴呈高黏附特征.在120℃热处理后,表面微结构恢复到了原始状态,在等离子进一步作用下,表面即可恢复到最初的低黏附水下超疏油状态.因此通过外压、热处理及等离子作用即可实现对表面微结构及其水下油黏附性能的可逆调控.研究表明,表面不同的微结构状态赋予表面不同的黏附性能,在原始表面液滴处于低黏附的Cassie态,而在坍塌结构表面水滴处于高黏附的Wenzel态.

二硫代氨基吡咯烷和维生素C对急性胰腺炎模型大鼠胰肝细胞粘附分子及超氧化物歧化酶表达的影响

目的 :探讨二硫代氨基吡咯烷 (PDTC)和维生素C(VitC)对急性胰腺炎 (AP)模型大鼠胰腺及肝脏中超氧化物歧化酶 (SOD :Mn -SOD ,Cu ,Zn -SOD)和细胞粘附分子 (ICAM - 1)表达的影响。方法 :经十二指肠壁进入胰管开口处 ,逆行加压注入 3%牛磺脱氧胆酸钠复制大鼠AP模型。模型随机分为 3组 :AP +生理盐水 (NS)组、AP +PDTC组和AP +VitC组 ,并在复制模型手术后 10min和 5h按分组给药。另设假手术组。各实验组于术后 1、5、10h取胰腺和肝脏 ,采用RT -PCR方法测定其ICAM - 1及Mn -SOD、Cu ,Zn -SOD的表达。结果 :AP +NS组胰腺和肝脏ICAM - 1表达高于假手术组 (P <0 0 5 ) ,胰腺Cu ,Zn -SOD表达低于假手术组 (P <0 0 5 )。AP +PDTC组和AP +VitC组胰腺Mn -SOD、Cu ,Zn -SOD表达高于AP +NS组 (P <0 0 5 ,P <0 0 1)。AP +PDTC组胰肝ICAM - 1表达低于AP+NS组 (P <0 0 5 )。结论 :结果提示 ,PDTC和VitC缓解AP的作用机制在于不仅它们自身是抗氧化剂 ,而且它们促进SOD的表达 ,同时PDTC还具有抑制ICAM - 1表达的作用。

CEACAM6、Syndecan-1、PDGFA、HLA-DRB5在溃疡性结肠炎中的表达和意义

目的:探讨差异表达的CEACAM6、Syndecan-1、PDGFA和HLA-DRB5基因在溃疡性结肠炎发生发展中的意义.方法:半定量RT-PCR检测21例溃疡性结肠炎患者及21例健康对照者外周血单个核细胞中CEACAM6、Syndecan-1、PDGFA、HLA-DRB5的表达水平.结果:CEACAM6、Syndecan-1、PDGFA在溃疡性结肠炎组表达水平较正常组高,差别有统计学意义(0.77±0.23vs0.58±0.14,1.16±0.39vs0.85±0.16,0.90±0.18vs0.78±0.13,均P<0.01),与基因芯片结果吻合;HLA-DRB5在溃疡性结肠炎组中较正常组中表达上调(0.58±0.19vs0.42±0.19,P<0.01),与基因芯片结果不相吻合(HLA-DRB5在UC组中的表达量是正常组的0.28倍).结论:基因芯片和RT-PCR分析基因表达变化都是可信的,CEACAM6、Syndecan-1、PDGFA、HLA-DRB5在溃疡性结肠炎的发病机制中有重要作用,通过对其功能进一步的研究,他们有可能成为溃疡性结肠炎诊治和病情监测的指标.