3D-printed,bi-layer,biomimetic artificial periosteum for boosting bone regeneration

Periosteum,a membrane covering the surface of the bone,plays an essential role in maintaining the function of bone tissue—and especially in providing nourishment and vascularization during the bone regeneration process.Currently,most artificial periostea have relatively weak mechanical strength and a rapid degradation rate,and they lack integrated angiogenesis and osteogenesis functions.In this study,a bi-layer,biomimetic,artificial periosteum composed of a methacrylated gelatin–nano-hydroxyapatite(GelMA-nHA)cambium layer and a poly(N-acryloyl 2-lycine)(PACG)-GelMA-Mg^(2+)fibrous layer was fabricated via 3D printing.The GelMA-nHA layer is shown to undertake the function of improving osteogenic differentiation of rat bone marrow mesenchymal stem cells with the sustainable release of Ca^(2+) from nHA nanoparticles.The hydrogen-bonding-strengthened P(ACG-GelMA-L)-Mg^(2+)hydrogel layer serves to protect the inner defect site and prolong degradation time(60 days)to match new bone regeneration.Furthermore,the released magnesium ion exhibits a prominent effect in regulating the polarization phenotype of macrophage cells into theM2 phenotype and thus promotes the angiogenesis of the human umbilical vein endothelial cells in vitro.This bi-layer artificial periosteum was implanted into a critical-sized cranial bone defect in rats,and the 12-week post-operative outcomes demonstrate optimal new bone regeneration.

High-Efficiency Wide-Band Cross-Polarization Conversion Using Bi-layered Metal Hole Pairs

We present a polarization converter composed of bi-layered metal films perforated with rectangle hole pairs in each film. The proposed converter can convert the polarization of an incident linearly-polarized electromagnetic wave to its orthogonal direction with high efficiency and large bandwidth in the infrared or microwave regions.To make sure of the mechanism of polarization conversion, the current and electric-field distributions at different resonant frequencies are analyzed. It is found that the cross-polarized transmission is due to the near-field coupling between hole pairs in neighboring metal films. Finally, a prototype of the proposed converter is fabricated and measured in the microwave region. Good agreement between the experimental and simulated results is obtained.

Development of controlled release bi-layered tablets containing oxycodone hydrochloride

Oxycodone hydrochloride is a semi-synthetic opioid agonist that provides very effective relief for moderate to severe pain in cancer and post-operative patients. Controlled release oxycodone formulations have been studied to enhance the therapeutic effect by providing constant release over the whole dosing interval and improve patient’s convenience by reducing the frequency of administration as well.

An analytic model for transient heat conduction in bi-layered structures with flexible serpentine heaters

Uniform heating of complex surfaces,especially non-developable surfaces,is a crucial problem that traditional rigid heaters cannot solve.Inspired by flexible electronic devices,a novel design for the stretchable heating film is proposed with the flexible serpentine wire embedded in the soft polymer film,which can be attached to non-developable surfaces conformally.It provides a new way for the stretchable heaters to realize uniform heating of complex surfaces.However,the thermal field of flexible serpentine heaters(FSHs)depends on the configurations of the embedded serpentine heating wire,which requires accurate theoretical prediction of real-time temperature distribution.Therefore,the analytical model for the transient heat conduction in FSHs is solved by the separation of variables method and validated by the finite element analysis(FEA)in this paper.Based on this model,the effects of the geometric parameters,such as the radius and the length of the serpentine heaters,on the thermal uniformity are systematically investigated.This study can help to design and fabricate flexible heaters with uniform heating in the future.

Treatment of corneal dermoid with lenticules from small incision lenticule extraction surgery:a surgery assisted by fibrin glue

AIM:To observe the clinical efficacy of the combined use of small incision lenticule extraction(SMILE)-derived lenticule patches in corneal dermoid excision,with fixation of the lenticule patches assisted by fibrin glue.METHODS:Seventeen eyes of 17 patients with corneal dermoid were treated with dermoid removal combined with SMILE-derived lenticule transplantation.All lenticule patches were fixed by fibrin glue.Ocular changes were assessed using slit lamp microscopy and anterior-segmental optical coherence tomography.The best-corrected visual acuity(BCVA)and ocular dioptric variations were examined preoperatively and postoperatively.Intraocular pressure(IOP)was also monitored in all visited time.RESULTS:Totally,18 lenticule patches were used on 17 eyes of 17 cornea dermoid patients.The mean follow-up time was 11.47±5.28mo.All lenticule patches we resuccessfullyg lued,kept on its location and maintained transparent during the follow-up time,with a consecutive epithelial cover for 1wk.Nine of the patients could coordinate visual and optometry exam well.Their preoperative BCVA is 0.60±0.35 in decimal,significantly improved to 0.80±0.26 in decimal at 6mo postoperatively(Z=-2.392,P=0.017),but the changes of their corneal astigmatism diopters showed no significance,with 2.22±1.91 D preoperatively,and 2.28±1.31 D at 6mo postoperatively(Z=-0.135,P=0.893).Limbal pannus formation occurred in 4(23.52%)cases and decreased with the application of tacrolimus eyedrops.IOP increased in 2(11.76%)cases,but well decreased by timolol maleate eyedrops.All the adult patients or guardians of minor patients were satisfied with the cosmetic improvement.CONCLUSION:Dermoid excision combined with transplantation of SMILE-derived lenticule patches using fibrin glue is a safe and effective novel tectonic keratoplasty procedure for corneal dermoid.

Fabrication of a Bi-layer Tubular Scaffold Consisted of a Dense Nanofibrous Inner Layer and a Porous Nanoyarn Outer Layer for Vascular Tissue Engineering

Recent years, it has attracted more attentions to increase the porosity and pore size of nanofibrous scaffolds to provide the for the cells to grow into the small-diameter vascular grafts. In this study, a novel bi-layer tubular scaffold with an inner layer and an outer layer was fabricated. The inner layer was random collagen/poly （ L-lactide-co-caprolactone ） I P （ LLA- CL） ] nanofibrous mat fabricated by conventional electrospinning and the outer layer was aligned collagen/P （LLA-CL） nanoyarns prepared by a dynamic liquid dectrospinning method. Fourier transform infrared spectroscopy （FTIR） was used to characterize the chemical structure. Scanning electron microscopy （ SEM ） was employed to observe the morphology of the layers and the cross- sectioned bi-layer tubular scaffold. A liquid displacement method was employed to measure the porosities of the inner and outer layers. Stress-strain curves were obtained to evaluate the mechanical properties of the two different layers and the bi-layer membrane. The diameters of the nanofibers and the nanoyarns were （480 ± 197 ） nm and （ 19.66 ± 4.05 ） μm, respectively. The outer layer had a significantly higher porosity and a larger pore size than those of the inner layer. Furthermore, the bi-layer membrane showed a good mechanical property which was suitable as small-diameter vascular graft. The results indicated that the bi-layer tubular scaffold had a great potential application in small vascular tissue engineering.

Developments of Cr-Si and Ni-Cr Single-Layer Thin-Film Resistors and a Bi-Layer Thin-Film Resistor with Adjustable Temperature Coefficient of Resistor

At first, Cr-Si (28 wt% Cr, 72 wt% Si) and Ni-Cr (80 wt% Ni, 20 wt% Cr) thin-film materials were deposited by using sputtering method at the same parameters, and their physical and electrical properties were investigated. The resistances of Cr-Si and Ni-Cr thin-film resistors decreased with the increase of deposition time (thickness) and their resistivity had no apparent variations as the deposition time increased. The temperature coefficient of resistance (TCR) of single-layer Cr-Si thin-film resistors was negative and the TCR value of single-layer Ni-Cr thin-film resistors was positive. For that, we used Cr-Si thin films as upper (or lower) layer and Ni-Cr thin films as lower (upper) layer to investigate a bi-layer thin-film structure. The deposition time of Ni-Cr thin films was fixed at 10 min and the deposition time of Cr-Si thin films was changed from 10 min to 60 min. We had found that as Cr-Si thin films were used as upper or lower layers they had similar deposition rates. We had also found that the thickness and stack method of Cr-Si thin films had large effects on the resistance and TCR values of the bi-layer thin-film resistors.

Optimization of Animal-Glue Binders for Casting Applications

In typical metal foundry applications,sand casting is still the most used technology.The related binder plays a very important role as its performances can directly influence the quality of castings.Among many binders,glues of animal origin have attracted much attention in recent years due to their reduced environmental impact.How-ever,they display some drawbacks such as the tendency to coagulate easily at room temperature and a relatively low strength.In this study,a novel gas-hardening casting binder was prepared using an animal glue and anhy-drous potassium carbonate as a hydrolyzing agent to avoid undesired agglomeration.Moreover,sodium pyropho-sphate and furfuryl alcohol were exploited as modifiers to obtain a binder with a high compressive strength.The best modification conditions,determined by means of an orthogonal design matrix approach,were 4 g of Na2CO3,sodium pyrophosphate,furfuryl alcohol and animal glue with a ratio of 4:12:100,at 85°C and with a duration of 115 min,respectively.The viscosity of the mixture obtained under these optimized conditions was 1250 mPa⋅s.The compressive strength of the binder,hardened by CO_(2) gas,was 4.00 MPa.Its gas evolution at 850°C was 15 ml⋅g-1,and its residual strength after 10 min calculation at 800°C was 0.01 MPa,which is high enough to meet the requirement of core-making in foundry.Moreover,after hydrolysis and further modification,animal glue and modifiers displayed a grafting reaction and an esterification reaction,respectively,which made the adhesive network denser and improved its thermal stability.

不同目标函数对新安江模型参数的敏感性和不确定性影响分析

目标函数的选择影响流域水文模型的参数率定结果。为深入探究不同目标函数对水文模型参数的敏感性和不确定性及径流模拟结果的影响,本文以福建省金溪池潭流域日径流模拟为例,采用SCEM-UA优化算法率定三水源新安江模型,选择纳什效率系数f_(1)、均方根误差f_(2)和Kling-Gupta效率系数f_(3)作为参数率定的目标函数,同时构建分别偏好f_(1)、f_(2)、f_(3)三者的组合多目标函数F_(1)、F_(2)和F_(3)共6个率定目标,比较不同率定目标下的径流模拟精度差异,采用Sobol全局敏感性分析方法定量对比分析不同目标函数下的新安江模型参数敏感性,最后基于GLUE方法分析丰枯水期和不同流量级别下的径流模拟不确定性。结果表明:(1)6个目标函数下,新安江模型的主要敏感参数识别结果一致;(2)F_(1),F_(2),F_(3)较单目标函数展现出更高的径流模拟精度;(3)在不同水文时期和不同流量级别下,f_(1)表现出较其他目标函数更高的覆盖率和较小的不确定性区间。不同目标函数下均呈现枯水期参数不确定性最小,且随流量级别的增大而径流模拟不确定性增加的规律。

凝聚剂组成对G-ABS高胶粉及ABS外观特性的影响

在使用凝聚剂从聚丁二烯与丙烯腈和苯乙烯的接枝共聚物(G-ABS)胶乳中回收G-ABS高胶粉的过程中,凝聚剂组成不但会改变高胶粉的粒径,还会对丙烯腈-丁二烯-苯乙烯三元共聚物(ABS)粒料的白度和色度稳定性造成影响。以冰乙酸/硫酸镁、硫酸/硫酸镁为凝聚剂,通过调整阳离子的配比,对比2组凝聚剂对G-ABS高胶粉和ABS外观特性的影响。结果表明:在确保凝聚浆液为酸性时,减少凝聚剂阳离子中H+占比,对粉料筛分粒径分布、氧化诱导时间没有明显影响,但ABS白度、热氧老化色度稳定性和粒料储存色度稳定性均有提升;与使用硫酸相比,使用冰乙酸能够显著提升ABS白度和热氧老化色度稳定性。

NBCA医用胶联合弹簧圈三明治法栓塞脾动脉瘤17例疗效分析

目的:探讨氰基丙烯酸异丁酯(NBCA)医用胶联合弹簧圈三明治法栓塞脾动脉瘤的疗效及安全性。方法:选择2018年3月至2023年7月采用经导管注入NBCA医用胶和弹簧圈三明治法栓塞脾动脉瘤的患者17例,回顾性分析临床资料和影像资料,评价栓塞成功率、临床疗效及手术相关并发症。结果:17例患者中男9例,女8例,年龄33~77岁;真性动脉瘤20例,假性动脉瘤2例;多发3例,单发14例;瘤体位于脾动脉近段3例,中段10例,远段9例。所有患者均成功栓塞,未发生严重手术并发症;术后随访3~36个月,腹部增强CT示脾动脉瘤铸型良好,未见复发、增大或破裂出血。结论:经导管NBCA医用胶联合弹簧圈三明治法栓塞脾动脉瘤成功率高,安全有效。

XperCT联合穿刺引导下Glubran-2胶肺小结节定位在胸腔镜肺结节切除术的临床应用

目的探讨XperCT联合穿刺引导下Glubran-2胶肺小结节定位在胸腔镜肺结节切除术的应用价值。方法回顾性分析2018年6月至2023年2月于济宁市第一人民医院单发肺小结节行胸腔镜切除术前在XperCT联合穿刺导航引导下采用Glubran-2胶定位67例患者的临床资料。统计肺结节大小、距脏层胸膜垂直的最大距离、定位技术成功率、穿刺次数、并发症、操作时间、术后病理结果。结果67例患者肺小结节平均最大直径8.7 mm,距脏层胸膜19.4 mm,均顺利完成术前定位,平均穿刺次数1.1次,未出现严重并发症,平均操作时间12.7 min,均获得明确的病理结果。结论XperCT联合穿刺导航引导下Glubran-2胶肺小结节定位准确、并发症少,是一种高效快速的定位方式,具有临床应用价值。

热风黏合烘箱有限元仿真分析与结构优化

为研究和提升热风黏合烘箱内部流场和温度场的均匀性,采用有限元分析方法对烘箱内部流场进行了仿真分析与优化。使用SolidWorks建立了烘箱流体域三维模型,根据烘箱工作时条件设定仿真计算的边界条件,通过实验测量得到纤维网的流阻数值,设定流阻相同的多孔介质模型代替纤维网实际结构,利用Fluent软件对烘箱内部流体域模型进行仿真计算,通过实验验证了仿真建模及计算的正确性。仿真结果表明:现有结构的烘箱上风道内流场不匀,纤维网表面温度场均匀性较差,针对仿真结果反映出的问题对烘箱结构进行了优化;优化后的烘箱仿真结果显示烘箱内部流场均匀性提升,纤维网上表面温度的总体均匀度由86.43%提升到93.06%。对烘箱进行结构优化后不仅提升了烘箱内部整体流场和温度场的均匀性,同时有利于降低烘箱的能耗。

一种壁画修复专用动物胶的制备及性能研究

为有效解决壁画修复常用胶水存在耐水性差、易受侵蚀等问题。研究针对当前我国常见壁画修复用胶水存在的性能缺陷,制备了一种专用于壁画修复的动物胶,该动物胶由牛皮等材料制成,具有无毒、耐腐蚀、兼容性强的优势。针对该动物胶的粘接性能进行分析,结果表明,与几种常见壁画修复用胶相比,本文制备动物胶的黏度、表面张力、粘接强度等综合粘接性能较为优秀;当牛皮胶质量占胶水总质量的2.5%时,胶水的光泽度表现显著优于其他胶水。

基于适用性试验的无机植筋锚固性能研究

现行植筋技术规程要求植筋过程应确保植筋孔干燥、无灰尘,但并非所有工程都能保证植筋条件达到规范要求。为研究植筋安装条件能否影响植筋锚固性能,参照欧洲的建筑紧固件锚栓规范ETAG 001设计植筋胶适用性试验,包括清孔效果试验和孔洞淹水试验。设计植筋直径为12mm和20mm,锚固深度为10d、15d和20d(d为植筋直径)的18组植筋拉拔试件,通过拉拔试验探究钢筋直径、锚固深度及植筋安装条件等因素对植筋锚固性能的影响。试验过程中测量植筋的应变及荷载-位移曲线。试验结果表明:安装条件对无机植筋锚固性能造成不同程度的影响。锚固深度为10d时适用性试验组的极限拉拔荷载最小约为对照组的54.90%,且破坏形式由混合破坏转变为钢筋拔出破坏;随着锚固深度的增加,安装条件对植筋锚固性能的影响逐渐减小,当深度达到20d时,适用性试验组的极限拉拔荷载与对照组相差小于10%。通过拉拔试验过程中钢筋应变的测量和计算,可知植筋试件在拉拔试验过程中粘结应力分布是不均匀的,粘结应力峰值靠近植筋加载段且峰值大小约为其他测点的1.5倍;此外,安装条件对不同试验组粘结应力的分布影响较小。

基于GLUE和PEST的CERES-Maize模型调参与验证研究

作物模型已逐渐成为干旱和半干旱地区优化农田水肥管理和实施节水灌溉的有力决策支持工具。为了探讨CERES—Maize模型模拟不同生育期受旱情况下夏玉米的生长发育、产量形成和土壤水分状况的模拟精度，进行了2013和2014年连续两季夏玉米田间分段受旱试验。试验将夏玉米整个生育期划分为苗期、拔节、抽雄和灌浆4个主要生长阶段，采用单个生育期受旱其他生育期灌水的方式，形成4个不同的受旱时段水平（Dl～D4），又根据夏玉米多年生育期降雨量，设置了70和110mm两个灌水水平（11和12），共形成8个处理，每个处理3次重复，在遮雨棚内按照裂区试验布设，此外设置1个各生育期均灌水110mm的对照处理（CK）。利用两年试验数据，采用DSSAT—GLUE和PEST两种不同的模型参数估计工具，对CERES—Maize模型的遗传参数进行估计，并对该模型的模拟精度和可靠性进行验证，此外还使用交叉验证法对CERES—Maize模型的整体模拟精度进行评估。结果表明，GLUE和PEST两种调参工具所得的模型参数均有较好的稳定性和收敛性，但PEST调参工具耗时较少，效率较高；CERES-Maize模型能较好地模拟充分灌水条件下夏玉米的生长发育、产量和土壤水分变化，绝对相对误差（ARE）和相对均方根误差（RRMSE）均在6％一8％之间；但是现有CERES—Maize模型无法模拟由于不同生育期受旱造成的夏玉米物候期的差异。此外，交叉验证结果发现夏玉米生长前期（特别是拔节期）受旱处理的数据参与模型校正时，模型的总体平均模拟误差较大，精度较低。CERES-Maize模型模拟前期受旱对玉米籽粒产量的影响时结果不够准确，这可能是由于该模型低估了早期水分胁迫条件下的LAI值，进而使得ET模拟不准确所造成的。总之，CERES-Maize模型对生育期前期（特别是拔节期）受早条件下夏玉米生长发育、产量形成和土壤水分变化的模拟还存在一定的不足，若将CERES-Maize模型应用于我国干旱和半干旱地区水分胁迫条件下玉米的生产管理和科学研究，应对模型进行相应的修正。

优化、RSA和GLUE方法在非线性环境模型参数识别中的比较

参数识别是数学模型应用的前提 ,本文对非线性环境模型常用的 3种参数识别方法进行了比较分析 .优化方法是出现最早、应用最广泛的参数识别方法之一 .但在观测误差存在的情况下 ,采用优化方法识别的最优参数进行模型预测 ,存在很大的决策风险 .考虑到这种不足 ,RSA方法和GLUE方法摒弃了识别单一最优参数的传统思维 ,而把识别参数扩大到多点组成的参数集 .RSA方法与GLUE方法不同的是 ,RSA方法把可行的参数点看成是同等接受的 ,而GLUE方法则根据模拟值与实测值的差别 ,确定其似然度 ,代表参数的可信度水平 .除参数识别以外 ,RSA方法和GLUE方法也是全局灵敏度分析的重要工具 .

似然度函数对GLUE方法的影响

GLUE方法是不确定性条件下参数识别的重要方法,似然度函数的选择是GLUE方法的关键.为克服观测误差和模型结构误差对研究结果的影响,利用合成的数据序列,以污染物衰减模型为基础,分析了似然度函数对参数识别和模型预测结果的影响.从识别结果来看,由于似然度函数的变化改变了参数似然度之间的对比,因此对参数识别及灵敏度分析的结果都产生了影响,甚至能够改变参数全局灵敏度的相对排序.从预测结果来看,似然度函数的变化影响了模型预测的分布,但即使预测结果的模糊性在减少,精度并没有相应地提高.因此,似然度函数的恰当选择对分析结果具有重要的影响,应结合研究问题的具体特点和对模拟结果的要求,采用概率论等相关方法选择出尽可能体现参数真实重要性的函数.

基于GLUE方法的城市雨洪模型参数不确定性分析

以北京市大红门排水片为例,构建基于SWMM(Storm Water Management Model)的城市雨洪模型,并基于GLUE方法(Generalized Likelihood Uncertainty Estimation)对模型参数的不确定性进行了分析。结果表明,所建城市雨洪模型能够较好的模拟区域的雨洪过程。在模型参数中,管道曼宁系数、不透水区洼蓄量以及河道曼宁系数的不确定性对模型结果的影响较为显著。GLUE方法能够在分析模型结果不确定性的同时给出敏感性参数,为城市雨洪模型的参数率定和进一步研制提供了有效工具。

基于GLUE方法的流域水文模型的不确定性分析

以东江流域中的星丰流域为研究对象,采用GLUE方法探讨了TOPMODEL模型在水文预报中的不确定性.研究结果表明,模型中的参数m、T0和RV较为敏感,它们的微小改变都将影响模拟结果,而参数SR0不太敏感.从两场次洪水的流量过程线可看出,模拟得到的流量过程线的上、下边界并不能完全包含实测流量过程线,总有一些实测流量落在90%的置信区间之外,说明TOPMODEL模型并不能完全模拟出该流域的流量过程,这正是由于模型的不确定性而引起的.