Detecting early changes in choroidal vascularity and thickness using optical coherence tomography in patients with corneal crosslinking for keratoconus

AIM:To investigate changes in choroidal thickness and vascularity in keratoconus patients treated with corneal crosslinking.METHODS:This study evaluated 28 eyes of 22 patients with keratoconus who underwent corneal crosslinking.The choroidal thicknesses were evaluated on enhanced depth imaging optical coherence tomography at the preoperative and postoperative 3d,1,and 3mo.Choroidal thickness in the four cardinal quadrants and the fovea were evaluated.The choroidal vascularity index was also calculated.RESULTS:There was no significant difference in central choroidal thickness between the preoperative and postoperative 3d,1mo(P>0.05).There was a significant increase in the 3mo(P=0.034)and a significant decrease in the horizontal choroidal vascularity index on the postoperative 3d(P=0.014),there was no statistically significant change in vertical axes and other visits in horizontal sections(P>0.05).CONCLUSION:This study sheds light on choroidal changes in postoperative corneal crosslinking for keratoconus.While it suggests the procedure’s relative safety for submacular choroid,more extensive research is necessary to confirm these findings and their clinical significance.

Stromal lenticule addition keratoplasty with corneal crosslinking for corneal ectasia secondary to FS-LASIK:a case series

●AIM:To explore the clinical efficacy and safety of stromal lenticule addition keratoplasty(SLAK)with corneal crosslinking(CXL)on patients with corneal ectasia secondary to femtosecond laser-assisted in situ keratomileusis(FS-LASIK).●METHODS:A series of 5 patients undertaking SLAK with CXL for the treatment of corneal ectasia secondary to FS-LASIK were followed for 4-9mo.The lenticules were collected from patients undertaking small incision lenticule extraction(SMILE)for the correction of myopia.Adding a stromal lenticule was aimed at improving the corneal thickness for the safe application of crosslinking and compensating for the thin cornea to improve its mechanical strength.●RESULTS:All surgeries were conducted successfully with no significant complications.Their best corrected visual acuity(BCVA)ranged from 0.05 to 0.8-2 before surgery.The pre-operational total corneal thickness ranged from 345-404μm and maximum keratometry(Kmax)ranged from 50.8 to 86.3.After the combination surgery,both the corneal keratometry(range 55.9 to 92.8)and total corneal thickness(range 413-482μm)significantly increased.Four out of 5 patients had improvement of corneal biomechanical parameters(reflected by stiffness parameter A1 in Corvis ST).However,3 patients showed decreased BCVA after surgery due to the development of irregular astigmatism and transient haze.Despite the onset of corneal edema right after SLAK,the corneal topography and thickness generally stabilized after 3mo.●CONCLUSION:SLAK with CXL is a potentially beneficial and safe therapy for advanced corneal ectasia.Future work needs to address the poor predictability of corneal refractometry and compare the outcomes of different surgical modes.

Carcinoma-associated fibroblast-derived lysyl oxidase-rich extracellular vesicles mediate collagen crosslinking and promote epithelial-mesenchymal transition via p-FAK/ p-paxillin/YAP signaling

Carcinoma-associated fibroblasts(CAFs)are the main cellular components of the tumor microenvironment and promote cancer progression by modifying the extracellular matrix(ECM).The tumor-associated ECM is characterized by collagen crosslinking catalyzed by lysyl oxidase(LOX).Small extracellular vesicles(sEVs)mediate cell-cell communication.However,the interactions between sEVs and the ECM remain unclear.Here,we demonstrated that sEVs released from oral squamous cell carcinoma(OSCC)-derived CAFs induce collagen crosslinking,thereby promoting epithelial-mesenchymal transition(EMT).CAF sEVs preferably bound to the ECM rather than being taken up by fibroblasts and induced collagen crosslinking,and a LOX inhibitor or blocking antibody suppressed this effect.Active LOX(αLOX),but not the LOX precursor,was enriched in CAF sEVs and interacted with periostin,fibronectin,and bone morphogenetic protein-1 on the surface of sEVs.CAF sEV-associated integrinα2β1 mediated the binding of CAF sEVs to collagen I,and blocking integrinα2β1 inhibited collagen crosslinking by interfering with CAF sEV binding to collagen I.CAF sEV-induced collagen crosslinking promoted the EMT of OSCC through FAK/paxillin/YAP pathway.Taken together,these findings reveal a novel role of CAF sEVs in tumor ECM remodeling,suggesting a critical mechanism for CAF-induced EMT of cancer cells.

Polyamine-Polymeric Micelle Hybrid Hydrogel: Microscopic Properties of Crosslinkers Affecting Macroscopic Rheological Properties of Hydrogel

We have developed a hybrid hydrogel that is formed from a crosslinkable polymeric micelle and a polyamine. Under optimal conditions, the hydrogel rapidly formed in one second after a crosslinkable polymeric micelle solution was mixed with a polyamine solution. We could change the hydrogel’s gelation properties, such as the storage modulus and gelation time by tuning the molecular weights of block copolymers and by tuning the pH of the dissolving-solvent of the hydrogel’s constituent components. Furthermore, we have clarified here that the structural difference among the micelles acting as crosslinkers can affect the gelation properties of the hydrogel. According to our findings, the hydrogel that was formed from the polymeric micelles possessing a highly packed (i.e., well-entangled or crosslinked) inner core exhibited a higher storage modulus than the hydrogel that was formed from the polymeric micelles possessing a lowly packed structure. Our results demonstrate that a microscopic structural difference among crosslinkers can induce a macroscopic change in the properties of the resulting hydrogels. For medical applications, the hydrogel proposed in the present paper can encapsulate the hydrophobic compounds in crosslinkers (polymeric micelles) so that the hydrogel can be available as the biomaterial for their sustained release.

Evaluation of different crosslinking methods in altering the properties of extrusion-printed chitosan-basedmulti-material hydrogel composites

Three-dimensional printing technologies exhibit tremendous potential in the advancing fields of tissue engineering and regenerative medicine due to the precise spatial control over depositing the biomaterial.Despite their widespread utilization and numerous advantages,the development of suitable novel biomaterials for extrusion-based 3D printing of scaffolds that support cell attachment,proliferation,and vascularization remains a challenge.Multi-material composite hydrogels present incredible potential in this field.Thus,in this work,a multi-material composite hydrogel with a promising formulation of chitosan/gelatin functionalized with egg white was developed,which provides good printability and shape fidelity.In addition,a series of comparative analyses of different crosslinking agents and processes based on tripolyphosphate(TPP),genipin(GP),and glutaraldehyde(GTA)were investigated and compared to select the ideal crosslinking strategy to enhance the physicochemical and biological properties of the fabricated scaffolds.All of the results indicate that the composite hydrogel and the resulting scaffolds utilizing TPP crosslinking have great potential in tissue engineering,especially for supporting neo-vessel growth into the scaffold and promoting angiogenesis within engineered tissues.

Crosslinking Mechanism of Soy Protein-based Adhesives based on Glyoxal and a Compound of Protein Model

The crosslinking mechanism of glyoxal and asparagine was analyzed,and the relationship between the mechanism and practical performances of soy protein-based adhesives was also discussed.It is shown that when pH=1 and 3,glyoxal reacted with asparagine in the form of major cyclic ether compounds.When pH=5,glyoxal reacted with asparagine in two structural forms of sodium glycollate and cyclic ether compounds.However,amidogens of asparagine were easy to develop protonation under acid conditions.Supplemented by the instability of cyclic ether compounds,the reaction activity and reaction degree between glyoxal and asparagine were relatively small.Under alkaline conditions,glyoxal mainly reacted with asparagine in the form of sodium glycollate.With the increase of pH,the polycondensation was more sufficient and the produced polycondensation products were more stable.The reaction mechanism between glyoxal and asparagine had strong correspondence to the practical performances of the adhesives.Glyoxal solution could develop crosslinking reactions with soy protein under both acid and alkaline conditions.Bonding strength and water resistance of the prepared soy protein-based adhesives were increased significantly.When pH>7,glyoxal had relatively high reaction activity and reaction intensity with soy protein,and the prepared adhesives had high crosslinking density and cohesion strength,showing relatively high bonding strength,water resistance and thermal stability.

Facile synthesis of chromium chloride/poly(methyl methacrylate) core/shell nanocapsules by inverse miniemulsion evaporation method and application as delayed crosslinker in secondary oil recovery

Cr(III)ehydrolyzed polyacrylamide(HPAM)gels have been extensively studied as a promising strategy controlling waste water production for mature oilfields.However,the gelation time of the current technologies is not long enough for in-depth placement.In this study,we report a novel synthesis method to obtain chromium chloride/poly(methyl methacrylate)(PMMA)nanocapsules which can significantly delay the gelation of HPAM through encapsulating the chromium chloride crosslinker.The chromium chloride-loaded nanocapsules(CreNC)are prepared via a facile inverse miniemulsion evaporation method during which the hydrophobic PMMA polymers,pre-dispersed in an organic solvent,were carefully controlled to precipitate onto stable aqueous miniemulsion droplets.The stable aqueous nanodroplets(W)containing Cr(III)are dispersed in a mixture of organic solvent(O1)with PMMA and nonsolvent medium(O2)to prepare an inverse miniemulsion.With the evaporation of the O1,PMMA forms CreNCs around the aqueous droplets.The CreNCs are readily transferred into water from the organic nonsolvent phase.The CreNCs exhibit the tunable size(358-983 nm),Cr loading(7.1%-19.1%),and Cr entrapment efficiency(11.7%-80.2%),with tunable zeta potentials in different PVA solutions.The CreNCs can delay release of Cr(III)and prolong the gelation time of HPAM up to 27 days.

Novel polyimide binder for achieving high-rate capability and long-term cycling stability of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode via constructing polar and micro-branched crosslinking network structure

LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)material,as the promising cathode candidate for next-generation highenergy lithium-ion batteries,has gained considerable attention for extremely high theoretical capacity and low cost.Nevertheless,the intrinsic drawbacks of NCM811 such as unstable structure and inevitable interface side reaction result in severe capacity decay and thermal runaway.Herein,a novel polyimide(denoted as PI-Om DT)constructed with the highly polar and micro-branched crosslinking network is reported as a binder material for NCM811 cathode.The micro-branched crosslinking network is achieved by using 1,3,5-Tris(4-aminophenoxy)benzene(TAPOB)as a crosslinker via condensation reaction,which endows excellent mechanical properties and large free volume.Meanwhile,the massive polar carboxyl(-COOH)groups provide strong adhesion sites to active NCM811 particles.These functions of PIOm DT binder collaboratively benefit to forming the mechanically robust and homogeneous coating layer with rapid Li+diffusion on the surface of NCM811,significantly stabilizing the cathode structure,suppressing the detrimental interface side reaction and guaranteeing the shorter ion-diffusion and electron-transfer paths,consequently enhancing electrochemical performance.As compared to the NCM811 with PVDF binder,the NCM811 using PI-Om DT binder delivers a superior high-rate capacity(121.07 vs.145.38 m Ah g^(-1))at 5 C rate and maintains a higher capacity retention(80.38%vs.91.6%)after100 cycles at 2.5–4.3 V.Particularly,at the high-voltage conditions up to 4.5 and 4.7 V,the NCM811 with PI-Om DT binder still maintains the remarkable capacity retention of 88.86%and 72.5%after 100 cycles,respectively,paving the way for addressing the high-voltage operating stability of the NCM811 cathode.Moreover,the full-charged NCM811 cathode with PI-Om DT binder exhibits a significantly enhanced thermal stability,improving the safety performance of batteries.This work opens a new avenue for developing high-energy NCM811 based lithium-ion batteries with long cycle-life and superior safety performance using a novel and effective binder.

可逆交联聚丁二烯网络的技术进展

简介了聚丁二烯的种类、优异性能及重要性,简述了聚丁二烯使用过程中硫化交联制备的含有不可逆交联网络带来的难以回收和资源浪费的问题,设计合成基于可逆交联键的聚丁二烯网络对于发展高弹性、高强度、可回收和其它功能的先进材料具有重要意义。构筑可逆交联聚丁二烯的关键是在聚丁二烯分子链上引入官能基团,再通过官能基团之间的反应或相互作用构筑可逆交联聚丁二烯网络。根据官能基团在聚丁二烯分子链的位置不同,介绍了基于链端官能化聚丁二烯的可逆交联网络、基于链中官能化聚丁二烯的可逆交联网络和基于链端和链中双重官能化聚丁二烯的可逆交联网络这3种聚丁二烯网络的制备方法和性能。最后提出,引入更多的可逆交联键以及功能基团,拓宽其应用领域是未来的重点研发方向。

基于淀粉微球交联剂的低浓度羟丙基胍胶压裂液性能研究

目的针对低渗透油藏,需要降低压裂液稠化剂用量,减少对储层的伤害,并确保压裂液具备延迟交联、携砂等性能和耐温耐剪切性能。方法利用反相乳液聚合法合成淀粉微球,通过硅配体和硼羟基修饰淀粉微球表面,制备了一种交联性能优良、伤害性低的微球型硅硼交联剂(KBSM)。结果KBSM交联剂能够实现多活性位点交联,增强交联密度,从而降低羟丙基胍胶(HPG)的用量,具有延迟交联特性。其延迟交联时间在2~6 min内可调。质量分数为0.2%的HPG交联冻胶在120℃、170 s-1剪切120 min后的黏度为80 mPa·s。交联冻胶中砂质量分数(以下简称携砂比)为40%时,陶粒沉降速度为0.1167 cm/min。加入质量分数为0.25%的过硫酸铵破胶剂可使交联冻胶在90℃下、120 min内完全破胶,且残渣质量浓度为214 mg/L。同时,破胶液的岩心损害率为26.55%。结论基于淀粉微球交联剂的低含量羟丙基胍胶压裂液对于降低低渗储层伤害有一定的指导意义。

高压XLPE电缆缓冲层缺陷研究现状综述

高压交联聚乙烯电缆因缓冲层缺陷引发的故障频发,已严重威胁到电力系统的安全运行。本文首先介绍了缓冲层的基本结构和作用,并在此基础上梳理了目前国内外对于缓冲层失效的相关研究;其次从缓冲层的材料特征和内部结构等角度结合电场仿真来分析缺陷发生的主要原因;之后对缓冲层缺陷中出现的白色粉末绝缘性能和理化特征进行总结,并提出其形成机理;最后对缓冲层缺陷的检测手段进行汇总,提出使用计算机断层成像技术对电缆缓冲层缺陷进行检测以弥补现有检测手段的不足,并建议对铝护套及缓冲层的材料或结构进行优化,以预防缓冲层缺陷的生成。

橡胶复合材料的Mullins效应

橡胶复合材料在大应变加载-卸载循环作用下总是发生应变软化和滞后性回复行为,即Mullins效应。该效应显著影响材料在循环载荷作用下的使役行为及其结构稳定性,但120年以来Mullins效应机理争议极大,其理论模型难以有效指导橡胶材料加工和Mullins效应调控。通过分析已提出的“填料结构”、填料-橡胶界面、橡胶相“破坏”等主要Mullins效应机理及其缺陷,结合Mullins效应所伴随的微观结构变化扼要介绍“破坏模型”及其理论的主要学术思想、应用和局限性,阐明理论研究分歧的主要原因。结合作者课题组的工作提出Mullins效应的黏弹性机制,展示若干Mullins效应调控策略,进一步展望理论研究和调控技术的发展方向。

双交联淀粉凝胶的制备及对结晶紫的吸附

实验选取红薯淀粉和高直链玉米淀粉、ECH为交联剂制备淀粉凝胶,再以硼砂、明胶及PEG2000为添加剂与淀粉进行二次交联制备双交联淀粉凝胶。并测试了凝胶的吸水性及对结晶紫(CV)的吸附性能。结果表明,双交联淀粉凝胶制备的最佳反应条件为:淀粉质量分数为10%,ECH与淀粉及碱与淀粉物质的量比分别为2:1和1:1,40℃下反应60 min得淀粉凝胶,再添加2%硼砂得到双交联淀粉凝胶。凝胶的吸水率最高可达330.2%;当CV初始浓度在10~100 mg/L时,凝胶对CV吸附率先增大后减小,50 mg/L时吸附率最高,为93.48%;100 mg/L时吸附量最大,为30.79 mg/g。

微交联聚吡咯衍生物的合成与光学性能

有机共轭聚合物因具有独特的结构和光电性能,在发光材料及器件领域有着广泛的研究和应用。以吡咯和单醛基苯甲醛为线形单体,以对苯二甲醛为交联单体,采用溶液缩聚法制备了4种蓝光微交联聚吡咯衍生物,并对其分子结构、聚集态结构、微观形貌、热行为、紫外-可见吸收和荧光性能等进行了分析,考察了取代基类型对其结构和光学性能的影响。研究表明,微交联聚吡咯衍生物具有较高的玻璃化转变温度和热稳定性能,为非晶态和亚微米级的球形堆积体;在340nm左右紫外光的激发下,微交联聚吡咯衍生物能够产生约473nm的可见光,属于蓝色发光材料;不同类型的取代基对微交联聚吡咯衍生物的结构和光学特性有所影响。该微交联聚吡咯衍生物制备简单,结构可调可控,在聚合物发光二极管领域有着潜在的应用。

AM-AMPS共聚吸水树脂的制备与性能研究

用丙烯酰胺(AM)和2-丙烯酰胺基-2-甲基丙磺酸(AMPS)两种单体采用溶液共聚方法,用过硫酸铵和亚硫酸氢钠作引发剂,N,N-亚甲基双丙烯酰胺作交联剂,制备了AM-AMPS共聚物吸水树脂。考察了AM/AMPS比例、引发剂用量、交联剂、pH、反应温度、反应时间等工艺条件对吸水倍率的影响。结果表明,AM/AMPS质量比为1/2~1/1,引发剂用量为0.3%,交联剂为0.06%~0.1%,pH值为7,反应温度在35~40℃,反应时间在2~4h时,制备的树脂有良好的吸水性。采用傅里叶变换红外光谱仪、热重分析仪和凝胶渗透色谱仪对产物进行了测试表征。

三羟甲基丙烷改性水性聚氨酯的制备及影响因素

三羟甲基丙烷(TMP)化学结构中有三个羟基,在水性聚氨酯的制备中起交联作用,可提高水性聚氨酯的耐水性、耐热性和力学性能.分别讨论异氰酸酯基和羟基的物质的量比(R值)、异氰酸酯的种类以及低分子多元醇对水性聚氨酯的性能影响;然后通过优化水性聚氨酯的合成工艺,并调控TMP的加入量,探究TMP对其性能的影响.结果表明,当使用聚碳酸酯二醇(PCDL)和四氢呋喃均聚醚(PTMEG)(物质的量比为1∶1)为软段,异佛尔酮二异氰酸酯(IPDI)为硬段,TMP质量分数为0.50%时,乳液稳定,耐水率为2.01%,拉伸强度为20MPa,断裂伸长率为108%.

一种壳聚糖改性产物的制备工艺及其产品吸附性能的研究

以壳聚糖(CTS)为母体,加入冰醋酸溶解得到CTS溶液,以无水乙醇为致孔剂,制备多孔壳聚糖微球,将制得的CTS微球与环氧氯丙烷(ECH)交联,制备出羟丙基壳聚糖微球(HPCTS),对产物进行红外光谱和电镜扫描性能表征。通过红外光谱图分析可以看出,ECH与CTS进行了交联反应。比较CTS和HPCTS的电镜扫描图片,发现HPCTS表面因为交联反应而形成大量多孔结构,增加了大量可供吸附重金属离子的空穴,使得HPCTS比交联前的表面积有了大幅提高。通过单因素实验,研究了制备HPCTS的工艺参数,在较优工艺参数下制备的产物交联度可达75.23%,产品具有良好的可再生性。

体育器材领域用二步法硅烷交联改性聚乙烯

通过化学方法与物理方法改善聚乙烯性能,使其拥有更具优势、更优异的力学性能,从而实现在体育器材领域的广泛应用。二步法硅烷交联改性工艺,不仅可促使改性聚乙烯内部呈现三维网状结构,还可有效改进材料综合力学性能。概述了聚乙烯硅烷交联改性工艺,以二步法工艺为例制备了体育器材领域用改性聚乙烯,进而详细分析了改性聚乙烯在体育器材领域的实际应用。

基于共混和层层自组装方法协同交联剂对琼胶/海藻酸钠复合膜性能的影响

以琼胶和海藻酸钠为成膜基质,通过共混和层层自组装两种方法制备了琼胶/海藻酸钠共混膜和双层膜,并引入交联剂柠檬酸和阿魏酸,通过测定复合膜的机械强度、耐水性、热稳定性、傅里叶变换红外光谱(Fourier transform infrared spectrometer,FT-IR)和微观结构等指标,探究了不同制膜方式结合交联剂对复合膜性能的影响。结果表明,与共混膜相比,双层膜表现出更优异的机械性能和耐水性,添加交联剂后,膜的水蒸气透过率(P<0.05)显著降低,拉伸强度、热稳定性和不透明度提高。其中柠檬酸交联的双层膜综合性能最佳,即拉伸强度51.57 MPa,断裂伸长率26.02%,水溶性24.42%,溶胀率101.67%。FT-IR分析表明柠檬酸通过与琼胶和海藻酸钠发生酯化反应形成CO进行共价交联,而阿魏酸通过与成膜基质形成氢键进行非共价交联。扫描电镜分析表明琼胶和海藻酸钠的相容性良好,各膜表面均平整、光滑,而添加交联剂后,膜截面褶皱减少,膜结构更加紧密。由此表明,层层自组装技术和交联剂的结合使用可以制备出综合性能更好的复合膜。

低浓度胍胶压裂液有机硼交联剂BOA的合成及其性能评价

针对胍胶压裂液体系胍胶使用浓度偏高、破胶后残渣含量较高的问题,开展低浓度胍胶压裂液体系有机硼交联剂的合成和性能评价研究。以硼酸、正丁醇、乙二醇及二乙烯三胺为原料合成有机硼交联剂并对其反应物加量进行优化,确定出有机硼交联剂BOA合成中反应物的优选质量分数分别为二乙烯三胺34.5%、硼酸14.3%、乙二醇38.7%和正丁醇6.9%。对交联剂进行性能评价,结果表明:有机硼交联剂BOA与0.2%胍胶交联形成的胍胶压裂液的黏度可达84 mPa·s;有机硼交联剂BOA与0.2%胍胶交联形成的胍胶压裂液具有良好的抗温抗剪切性,在100 s^(-1)下逐渐升温至90℃、剪切60 min时及在60℃、100 s^(-1)下剪切90 min时胍胶压裂液的黏度均维持在90 mPa·s,且具有滤失低(滤失系数为2.0×10^(-4)m/min^(1/2))、携砂性能好(悬砂沉降速度为0.045 mm/s)、破胶速度快(在90 min内可完全破胶)、破胶液黏度<5 mPa·s、残渣含量较低(151 mg/L)的优势,可满足压裂液现场施工要求。