Electrochemical and surface analyses of nanostructured Ti–24Nb–4Zr–8Sn alloys in simulated body solution

The use of nanostructuring to improve the stability of passive thin films on biomaterials can enhance their effectiveness in corrosion resistance and reduce the release of ions. The thickness of the ultrathin films that cover Ti and Ti alloys (only several nanometers) has prevented researchers from establishing systematic methods for their characterization. This study employed a multifunctional biomedical titanium alloy Ti–24Nb–4Zr–8Sn (wt.%) as a model material. Coarse-grained (CG) and nanostructured (NS) alloys were analyzed in 0.9% NaCl solution at 37 °C. To reveal the details of the passive film, a method of sample preparation producing a passive layer suitable for transmission electron microscope analysis was developed. Electrochemical corrosion behavior was evaluated by potentiodynamic polarization tests and Mott–Schottky measurements. Surface depth chemical profile and morphology evolution were performed by X-ray photoelectron spectroscopy and in situ atomic force microscopy, respectively. A mechanism was proposed on the basis of the point defect model to compare the corrosion resistance of the passive film on NS and CG alloys. Results showed that the protective amorphous film on NS alloy is thicker, denser and more homogeneous with fewer defects than that on CG alloy. The film on NS alloy contains more oxygen and corrosion-resistant elements (Ti and Nb), as well as their suboxides, compared with the film on CG alloy. These characteristics can be attributed to the rapid, uniform growth of the passive film facilitated by nanostructuring.     

Stress and damage at the bur‐prosthesis interface in dental adjustments of a leucite‐reinforced glass ceramic

Summary This article reports on the effects of dental adjustment parameters on stress and damage induced in a leucite‐reinforced glass ceramic using a high‐speed dental handpiece and coarse diamond burs. As one of machinable dental ceramics for prosthetic restorations, a leucite‐reinforced glass ceramic has higher fracture toughness than feldspar porcelains. However, the extent of subsurface damage and stress induced in clinical dental adjustments is unknown. Tensile, shear, compressive and von Mises stresses at the bur–ceramic interface were investigated as functions of dental adjustment parameters using finite element analysis (FEA). The depths of subsurface damage were predicted using FEA according to the maximum principal stress criterion and experimentally measured using scanning electron microscopy (SEM). The resulting predicted subsurface damage depths agree well with the experimentally measured data. Both adjustment parameters, depth of cut and feed rate, were found to have significant influences on adjustment‐induced stresses (P < 0·01) and subsurface damage (P < 0·01). It is also found that the predicted and measured subsurface damage depths increased linearly with the diamond grit depth of cut.     

实现医院X光片共享信息系统的安全策略

随着医院信息化建设的深入发展,为保证医院数据的连续性、完整性和准确性,信息系统需要24h不间断运行。因此,如何保证信息系统正常运行及信息安全,就成为一个重要问题,涉及到网络、环境、人等各方面因素。     

Reversible interconversion of carbon dioxide and formate by an electroactive enzyme

Carbon dioxide (CO₂) is a kinetically and thermodynamically stable molecule. It is easily formed by the oxidation of organic molecules, during combustion or respiration, but is difficult to reduce. The production of reduced carbon compounds from CO₂ is an attractive proposition, because carbon-neutral energy sources could be used to generate fuel resources and sequester CO₂ from the atmosphere. However, available methods for the electrochemical reduction of CO₂ require excessive overpotentials (are energetically wasteful) and produce mixtures of products. Here, we show that a tungsten-containing formate dehydrogenase enzyme (FDH1) adsorbed to an electrode surface catalyzes the efficient electrochemical reduction of CO₂ to formate. Electrocatalysis by FDH1 is thermodynamically reversible—only small overpotentials are required, and the point of zero net catalytic current defines the reduction potential. It occurs under thoroughly mild conditions, and formate is the only product. Both as a homogeneous catalyst and on the electrode, FDH1 catalyzes CO₂ reduction with a rate more than two orders of magnitude faster than that of any known catalyst for the same reaction. Formate oxidation is more than five times faster than CO₂ reduction. Thermodynamically, formate and hydrogen are oxidized at similar potentials, so formate is a viable energy source in its own right as well as an industrially important feedstock and a stable intermediate in the conversion of CO₂ to methanol and methane. FDH1 demonstrates the feasibility of interconverting CO₂ and formate electrochemically, and it is a template for the development of robust synthetic catalysts suitable for practical applications.     

长期配戴硬性角膜接触镜对泪膜稳定性的影响

目的探讨长期配戴硬性角膜接触镜对泪膜稳定性的影响。方法选取80例(160眼)患者分成四组:硬性角膜接触镜(RGP组):长期配戴RGP(20例,40眼);角膜塑形镜组:长期夜间配戴角膜塑形镜(22例,44眼);软性接触镜组:长期配戴软性接触镜(20例,40眼);对照组:为无角膜接触镜配戴史的低度近视患者(18例,36眼),分别在戴镜前和戴镜后1个月、6个月、1年、2年检测视力,施墨(Schirmer I)试验检测泪腺分泌功能,泪膜破裂时间(BUT)测定泪膜破裂时间,结膜印迹细胞学(CIC)观察结膜表层细胞形态学改变及结膜杯状细胞数目,泪膜羊齿状实验评估泪液中蛋白质含量的变化,观察结果进行统计学分析。结果各实验组的泪腺分泌功能和泪膜破裂时间均降低,与对照组间比较差异有统计学意义(P<0.05),各实验组长期持续配戴角膜接触镜后结膜杯状细胞减少,且不能形成良好的蕨样变现象。结论长期配戴角膜接触镜可致泪膜稳定性下降,泪液分泌量减少。     

两种手术治疗翼状胬肉术后泪膜稳定性观察

目的：评价两种不同手术方法治疗翼状胬肉对泪膜稳定性的影响。方法选取翼状胬肉患者60例60眼随机分为A、B两组,各30例30眼,A组行翼状胬肉切除联合羊膜移植术,B组行翼状胬肉切除联合角膜缘干细胞移植术,比较两组间术前、术后泪液分泌试验（Schirmerl试验）、泪膜破裂时间（BUT）、泪液羊齿状物试验（TFT）,评估手术对泪膜稳定性的影响。结果 Schirmerl试验：A组和B组术后与术前相比差异均无显著性(P>0.05),A组与B组比较差异无显著性(P>0.05)。BUT：A组和B组术后与术前相比差异均有显著性(P<0.05),术前1d、术后2周、术后4周数值A组与B组比较差异无显著性(P>0.05);术后12周B组BUT较A组改善明显,差异有显著性(P<0.05)。 TFT：A组和B组术后与术前相比差异均有显著性(P<0.05),A组与B组比较差异无显著性(P>0.05)。结论翼状胬肉切除联合角膜缘干细胞移植术与翼状胬肉切除联合羊膜移植术,两种手术方式术后泪膜稳定性较术前均有改善;两者相互比较,术后早期泪膜稳定性改善无明显差异,但3个月后前者对泪膜改善更佳。     

滑膜骨软骨瘤病的X线片特征及其临床意义

目的 探讨滑膜骨软骨瘤病的X线片特征及其临床诊断价值和意义.方法 回顾性分析我院2012年5月至2013年5月收治的25例经手术病理证实为滑膜骨软骨瘤病的患者的临床及影像学资料,分析并总结其X线片特征.结果 本组25例患者患侧关节均可检测出大小不等、形态各异的游离体,18例患者出现单游离体,7例患者出现多游离体,所有游离体直径介于0.3～2.2cm之间,成堆或分散存在,3患者伴有关节间隙变窄,12例患者伴有退行性骨关节变化,经手术取出的游离体以及滑膜软骨钙化结节明显多于且大于X线片.结论 X线影像学检查对滑膜骨软骨瘤病的诊断具有一定的意义,但不同的软骨结节钙化和骨化程度会影响结果的准确性,降低确诊率,故最好以手术病理检查来确诊滑膜骨软骨瘤病.     

Bone marrow‐on‐a‐chip: Long‐term culture of human haematopoietic stem cells in a three‐dimensional microfluidic environment

Multipotent haematopoietic stem and progenitor cells (HSPCs) are the source for all blood cell types. The bone marrow stem cell niche in which the HSPCs are maintained is known to be vital for their maintenance. Unfortunately, to date, no in vitro model exists that accurately mimics the aspects of the bone marrow niche and simultaneously allows the long‐term culture of HSPCs. In this study, a novel three‐dimensional coculture model is presented, based on a hydroxyapatite coated zirconium oxide scaffold, comprising of human mesenchymal stromal cells (MSCs) and cord blood derived HSPCs, enabling successful HSPC culture for a time span of 28 days within the microfluidic multiorgan chip. The HSPCs were found to stay in their primitive state (CD34⁺CD38^?) and capable of granulocyte, erythrocyte, macrophage, megakaryocyte colony formation. Furthermore, a microenvironment was formed bearing molecular and structural similarity to the in vivo bone marrow niche containing extracellular matrix and signalling molecules known to play an important role in HSPC homeostasis. Here, a novel human in vitro bone marrow model is presented for the first time, capable of long‐term culture of primitive HSPCs in a microfluidic environment.     

3L透明膜作为中药脐疗贴膜的效果观察

目的：观察医用3L透明膜作为中药脐疗贴膜的应用效果。方法将160例需要进行中药脐疗的患者随机分为对照组和观察组各80例,对照组采用常规一次性医用胶带固定药饼,观察组选用3L透明膜作为贴敷材料,12 h后对2组的贴敷效果进行观察比较。结果观察组所使用的3L透明膜粘贴牢固,药饼无脱落;局部皮肤完好,无过敏反应,且贴敷部位皮肤视野清晰,有利于观察脐部皮肤情况。结论医用3L透明膜作为中药脐疗贴膜的应用效果优于普通医用胶带,值得临床推广应用。     

不同手术方式治疗翼状胬肉对泪膜稳定性的影响

目的：评价不同手术方式治疗翼状胬肉的效果,并观察其对泪膜稳定性的影响。
　　方法：选取翼状胬肉患者120例120眼,按照手术方式分为三组,每组各40例40眼。比较各组间术前、术后Shirmer试验（ ShirmerⅠtest,SⅠt）和泪膜破裂时间（ tear break－up time, BUT ）,角膜荧光素染色（ corneal fluorescein staining , CFS）及术后复发率,评估手术疗效和对泪膜功能的影响。
　　结果：术后1 mo A组BUT 较术前无显著差异; B组和C组较术前的变化有显著差异（ P＜0．05）,但两组之间差异无统计学意义;术后1mo,三组SⅠt和术前比较差异均无统计学意义;术后1mo,A组与B组及C组CFS存在显著性差异（ P＜0．05）;但B组和C组差异无统计学意义。术后3mo,A组BUT较术前无显著差异;B组及C组较术前有显著性差异（P＜0．05）,但B组及C组间差异无统计学意义;术后3mo,A组S I t较术前无显著差异;B组及C组S I t较术前有显著性差异（ P＜0．05）,但两组间差异无统计学意义;术后3mo,A组术前与B组及C组CFS无显著差异。随访10mo,经比较A组与B、C两组复发率存在
　　显著差异（ P＜0．05）,B组与C 组存在差异,但无统计学意义。夏季手术较冬季手术更容易复发。
　　结论：翼状胬肉切除联合角膜缘干细胞移植封闭Tenon囊是目前治疗翼状胬肉的较理想手术方式,降低复发率并使患者泪膜功能得到一定程度的改善。