In Situ Surface Tailoring with Zwitterionic Carboxybetaine Moieties on Self-Assembled Thin Film for Antifouling Biointerfaces

A novel biointerface bearing zwitterionic carboxybetaine moieties was developed for effective resistance to nonspecific adsorption of proteins and blood cells. Self-assembled thin films (SAFs) of (N,N-dimethylaminopropyl) trimethoxysilane were formed as mattress layers by either vapor or solution deposition. Subsequently, the tertiary amine head groups on SAFs were reacted with β-propiolactone to give zwitterionic carboxybetaine moieties via in situ synthesis. The optimal reaction time of 8 h for both preparation methods was verified by static contact angle measurements. According to the X-ray photoelectron spectroscopy, 67.3% of amine groups on SAFs prepared from the vapor deposition was converted to the zwitterionic structures after reaction of β-propiolactone. The antifouling properties of the zwitterionic biointerfaces were quantitatively evaluated in the presence of protein solutions using a quartz crystal microbalance with dissipation, showing a great improvement by factors of 6.5 and 20.2 from tertiary amine SAFs and bare SiO₂ surfaces, respectively. More importantly, the zwitterionic SAFs were brought to contact with undiluted human blood in chaotic-mixer microfluidic systems; the results present their capability to effectively repel blood cell adhesion. Accordingly, in this work, development of carboxybetaine SAFs offers a facile yet effective strategy to fabricate biocompatible biointerfaces for a variety of potential applications in surface coatings for medical devices.     

Surface chemistry: key to control and advance myriad technologies

This special issue on surface chemistry is introduced with a brief history of the field, a summary of the importance of surface chemistry in technological applications, a brief overview of some of the most important recent developments in this field, and a look forward to some of its most exciting future directions. This collection of invited articles is intended to provide a snapshot of current developments in the field, exemplify the state of the art in fundamental research in surface chemistry, and highlight some possibilities in the future. Here, we show how those articles fit together in the bigger picture of this field.     

Mayenite Synthesis from Hydroxide Precursors: Structure Formation and Active Sites on Its Surface

We studied the formation process of a mayenite structure from hydroxide precursors in different gas media. According to X-ray diffraction data, this method allows a well-crystallized mayenite (Ca₁₂Al₁₄O₃₃ or C12A7) phase to be obtained at low (500–900 °C) temperatures with an insignificant impurity of CaO. It was shown that the lattice parameters for C12A7 obtained in an inert atmosphere (Ar) were lower when compared with similar samples in the air. These results can be explained by the different levels of oxygen nonstoichiometry in the resulting phase. We noted that sintering and crystallization of mayenite proceeds at lower temperatures in Ar than in the air medium. We found the presence of donor and acceptor active sites on the surface of mayenite, which was detected by the spin probe method. The specific (per unit surface) concentration of such sites (2.5 × 10¹⁶ m⁻² and 1.5 × 10¹⁵ m⁻² for donor and acceptor sites, respectively) is comparable to that of γ-Al₂O₃, which is traditionally used as catalyst support. This allows it to be used in adsorption and catalytic technologies, taking into account its high specific surface area (~30–50 m²/g at a low synthesis temperature).     

Thermochemical Laser-Induced Periodic Surface Structures Formation by Femtosecond Laser on Hf Thin Films in Air and Vacuum

Thermochemical laser-induced periodic surface structures (TLIPSS) are a relatively new type of periodic structures formed in the focal area of linear polarized laser radiation by the thermally stimulated reaction of oxidation. The high regularity of the structures and the possibility of forming high-ordered structures over a large area open up possibilities for the practical application for changing the optical and physical properties of materials surface. Since the mechanism of formation of these structures is based on a chemical oxidation reaction, an intriguing question involves the influence of air pressure on the quality of structure formation. This paper presents the results on the TLIPSS formation on a thin hafnium film with fs IR laser radiation at various ambient air pressures from 4 Torr to 760 Torr. Despite the decrease in the oxygen content in the ambient environment by two orders of magnitude, the formation of high-ordered TLIPSS (dispersion in the LIPSS orientation angle δθ < 5°) with a period of ≈700 nm occurs within a wide range of parameters variation (laser power, scanning speed). This behavior of TLIPSS formation is in agreement with experimental data obtained earlier on the study of the kinetics of high-temperature oxidation of hafnium at various oxygen pressures.     

Effect of Surface Ultrasonic Rolling Treatment on Rolling Contact Fatigue Life of D2 Wheel Steel

A GPM-30 fatigue machine was used to investigate the influence of surface ultrasonic rolling (SURT) on the rolling contact fatigue (RCF) life of D2 wheel steel. The experimental results present that the RCF life of the grinding processing sample is 4.1 × 10⁵ cycles. During the RCF process, the flaking of the fine grain layer and high surface roughness of the grinding processing sample cause the production of RCF cracks. When the samples are treated by SURT with 0.2 MPa and 0.4 MPa, the RCF life is 9.2 × 10⁵ cycles and 9.6 × 10⁵ cycles, respectively. After SURT, the surface roughness of the samples is reduced, and a certain thickness of gradient-plastic-deformation layer and a residual-compressive-stress layer are produced. These factors lead to the improvement of the RCF property. However, when the static pressure increases to 0.6 MPa during SURT, the RCF life of the sample is reduced during RCF testing. The micro-cracks, which are formed during SURT, become the crack source and cause the formation of RCF cracks, decreasing of the RCF life.     

恶性疟原虫感染的红细胞膜表面蛋白1模拟肽的筛选及鉴定

目的 筛选恶性疟原虫感染的红细胞膜表面蛋白1（PfEMP?鄄1）的噬菌体表位模拟肽。 方法 细胞间粘附分子ICAM-1模拟12肽（KLYLIAEGSVAA）能模拟ICAM-1分子与疟原虫感染红细胞结合的功能，以展示该短肽的噬菌体为靶，采用差减筛选法（subtraction method）对噬菌体环7肽库进行3轮筛选，通过ELISA、竞争抑制试验鉴定获得的噬菌体短肽与ICAM-1之间的结合特性。对阳性克隆进行DNA及氨基酸序列分析并与PfEMP-1氨基酸序列进行同源性比较。 结果 ELISA筛选22个克隆有3个为阳性克隆，氨基酸序列分析显示2个克隆的展示的短肽序列为C-ITAVPVR-C，另1为C-DIMGGYN-C。同源性分析未发现2短肽序列与野生型MC株恶性疟原虫PfEMP-1的氨基酸序列有同源性。但竞争抑制试验显示3个阳性克隆均可与15.2单抗间互相竞争抑制与ICAM-1分子的结合。 结论 获得2种PfEMP-1噬菌体构象表位模拟肽，两短肽能与ICAM-1分子特异性结合。     

Evolution of Topological Surface States Following Sb Layer Adsorption on Bi2Se3

Thin antimony layers adsorbed on bismuth selenide (Bi2Se3) present an exciting topological insulator system. Much recent effort has been made to understand the synthesis and electronic properties of the heterostructure, particularly the migration of the topological surface states under adsorption. However, the intertwinement of the topological surface states of the pristine Bi2Se3 substrate with the Sb adlayer remains unclear. In this theoretical work, we apply density functional theory (DFT) to model heterostructures of single and double atomic layers of Sb on a bismuth selenide substrate. We thereby discuss established and alternative structural models, as well as the hybridization of topological surface states with the Sb states. Concerning the geometry, we reveal the possibility of structures with inverted Sb layers which are energetically close to the established ones. The formation energy differences are below 10 meV/atom. Concerning the hybridization, we trace the band structure evolution as a function of the adlayer-substrate distance. By following changes in the connection between the Kramers pairs, we extract a series of topological phase transitions. This allows us to explain the origin of the complex band structure, and ultimately complete our knowledge about this peculiar system.     

C型钠尿肽与甲亢性肥大心房血流动力学及内分泌功能的关系

背景 C 型钠尿肽(CNP)是一种选择性的颗粒性膜结合型鸟苷酸环化酶(pGC),与钠尿肽受体 B(NPR-B)结合。正常生理情况下,CNP 对心房内分泌功能的作用已有报道,然而其作用在甲亢性肥大心房中发生何变化尚不清楚。目的探讨 CNP 对甲亢性肥大心房内分泌功能的影响。方法利用家兔的离体搏动心房灌流模型,采用放射免疫分析方法,研究在甲亢性肥大心脏中 CNP 对心房动力和内分泌功能的影响。结果甲状腺功能正常的心房(对照组,n=6)中,CNP(100 nmol/L)抑制心房每搏输出量、每搏压和心房钠尿肽(ANP)分泌,其幅度分别为(51.0±7.2)%、(37.3±3.8)%和(61.4±3.9)%。而在甲亢性肥大心房(甲亢组,n=7)中,CNP 反而增加心房每搏输出量和每搏压,其幅度分别为(16.9±11.1)%和(16.1±7.0)%;CNP 抑制心房 ANP分泌,其幅度为(40.0±4.3)%。与对照组相比,CNP 对甲亢性肥大心房 ANP 分泌的抑制效应明显减弱。结论在甲亢性肥大心脏中,CNP 对心房血流动力学及内分泌功能的作用发生了显著变化。     

Observation of a Flat and Extended Surface State in a Topological Semimetal

A flat band structure in momentum space is considered key for the realization of novel phenomena. A topological flat band, also known as a drumhead state, is an ideal platform to drive new exotic topological quantum phases. Using angle-resolved photoemission spectroscopy experiments, we reveal the emergence of a highly localized surface state in a topological semimetal BaAl4 and provide its full energy and momentum space topology. We find that the observed surface state is localized in momentum, inside a square-shaped bulk Dirac nodal loop, and in energy, leading to a flat band and a peak in the density of state. These results imply this class of materials as an experimental realization of drumhead surface states and provide an important reference for future studies of the fundamental physics of correlated quantum effects in topological materials.     

Surface Testing of Dental Biomaterials—Determination of Contact Angle and Surface Free Energy

The key goal of this study was to characterize surface properties of chosen dental materials on the base on the contact angle measurements and surface free energy calculations. Tested materials were incubated in the simulated oral environment and drinks to estimate an influence of conditions similar to those in the oral cavity on wetting and energetic state of the surface. Types of materials were as follows: denture acrylic resins, composite and PET-G dental retainer to compare basic materials used in a prosthetics, restorative dentistry and orthodontics. The sessile drop method was used to measure the contact angle with the use of several liquids. Values of the surface free energies were estimated based on the Owens–Wendt, van Oss–Chaudhury–Good and Zisman’s methods. The research showed that surface wetting depends on the material composition and storage conditions. The most significance changes of CA were observed for acrylic resins (84.7° ± 3.8° to 65.5° ± 3.5°) and composites (58.8° ± 4.1° to 49.1° ± 5.7°) stored in orange juice, and for retainers (81.9° ± 1.8° to 99.6° ± 4.5°) incubated in the saline solution. An analysis of the critical surface energy showed that acrylic materials are in the zone of good adhesion (values above 40 mJ/m²), while BIS-GMA composites are in the zone of poor adhesion (values below 30 mJ/m²). Study of the surface energy of different dental materials may contribute to the development of the thermodynamic model of bacterial adhesion, based on the surface free energies, and accelerate the investigation of biomaterial interaction in the biological environment.     

Area Postrema Lesion Alters the Effects of Peptide YY on 2-DG-Stimulated Pancreatic Exocrine Secretion

Previously we demonstrated that circulating peptide YY (PYY), which inhibits pancreatic exocrine secretion, binds to specific receptors in the area postrema (AP); therefore we have tested the hypothesis that the removal of the AP (APX) will alter the effects of PYY on pancreatic secretion in awake rats. One-month after AP lesion or sham lesion, rats were implanted with pancreatic, biliary, duodenal, and intravenous catheters. After recovery from the surgery, unanesthetized rats were infused with vehicle or PYY (30 pmol/kg/hr or 100 pmol/kg/hr) under basal or 2-deoxy-d-glucose (2-DG) stimulated (75 mg/kg, intravenous bolus) conditions. PYY at 30 pmol/kg/hr inhibited basal pancreatic fluid secretion in sham-operated rats, but not APX rats. PYY at 100 pmol/kg/hr stimulated basal pancreatic protein secretion in sham-operated rats, and this effect was also lost in APX rats. PYY at 30 and 100pmol/kg/hr inhibited peak 2-DG stimulated protein secretion to a greater extent in APX rats as compared to sham-operated rats (P < 0.05). Since PYY inhibition of basal pancreatic secretion is AP dependent and inhibition of 2-DG stimulated pancreatic secretion is AP independent, we conclude that the 2-DG pathway of pancreatic secretion differs from the pathway responsible for basal secretion, and that APX potentiates the inhibitory effect of PYY on the 2-DG pathway.     

Review of the Effect of Surface Coating Modification on Magnesium Alloy Biocompatibility

Magnesium alloy, as an absorbable and implantable biomaterial, has been greatly developed in the application field of biomaterials in recent years due to its excellent biocompatibility and biomechanics. However, due to the poor corrosion resistance of magnesium alloy in the physiological environment, the degradation rate will be unbalanced, which seriously affects the clinical use. There are two main ways to improve the corrosion resistance of magnesium alloy: one is by adding alloying elements, the other is by surface modification technology. Compared with adding alloy elements, the surface coating modification has the following advantages: (1) The surface coating modification is carried out without changing the matrix elements of magnesium alloy, avoiding the introduction of other elements; (2) The corrosion resistance of magnesium alloy can be improved by relatively simple physical, chemical, or electrochemical improvement. From the perspective of corrosion resistance and biocompatibility of biomedical magnesium alloy materials, this paper summarizes the application and characteristics of six different surface coating modifications in the biomedical magnesium alloy field, including chemical conversion method, micro-arc oxidation method, sol-gel method, electrophoretic deposition, hydrothermal method, and thermal spraying method. In the last section, it looks forward to the development prospect of surface coating modification and points out that preparing modified coatings on the implant surface combined with various modification post-treatment technologies is the main direction to improve biocompatibility and realize clinical functionalization.     

内皮素和降钙素基因相关肽对异丙肾上腺素致心肌损伤的影响

本实验在大鼠异丙肾上腺素（ＩＳＯ）心肌损伤模型上，观察了内皮素（ＥＴ）及降钙素基因相关肽（ＣＧＲＰ）对ＩＳＯ损伤心肌作用的影响．结果表明：ＥＴ明显加重ＩＳＯ对心肌的损伤，ＣＧＲＰ则能减轻ＩＳＯ对心肌的损伤及ＩＳＯ与ＥＴ对心肌的协同损伤．提示心肌病理情况下，ＥＴ是一种促损伤因素，而ＣＧＲＰ是抗损伤因素．     

Effects of Ultrasonic Surface Rolling Processing and Subsequent Recovery Treatment on the Wear Resistance of AZ91D Mg Alloy

AZ91D Mg alloy was treated by ultrasonic surface rolling processing (USRP) and subsequent recovery treatment at different temperatures. The dry sliding friction test was performed to investigate the effects of USRP and subsequent recovery treatment on the wear resistance of AZ91D Mg alloy by a ball-on-plate tribometer. The microstructure, properties of plastic deformation layer and worn morphology were observed by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) analysis and microhardness tester. Results illustrate that the grains of AZ91D Mg alloy surface layer are refined to nanocrystallines. The maximum microhardness of the top surface of the USRP sample reaches 102.3 HV. When USRP samples are treated by recovery treatment at 150 °C, 200 °C and 250 °C, the microhardness of the top surface decreases to 90.68 HV, 79.29 HV and 75.06 HV, respectively. The friction coefficient (FC) and wear volume loss of the USRP-R-150 sample are the lowest among all the samples. The worn surface morphology of the USRP-R-150 sample is smoother than that of other samples, indicating that the wear resistance of AZ91D Mg alloy treated by USRP and recovery treatment at 150 °C is improved significantly.     

A2BC-Type Porphyrin SAM on Gold Surface for Bacteria Detection Applications: Synthesis and Surface Functionalization

Currently used elaborate technologies for the detection of bacteria can be improved in regard to their time consumption, labor intensity, accuracy and reproducibility. Well-known electrical measurement methods might connect highly sensitive sensing systems with biological requirements. The development of modified sensor surfaces with self-assembled monolayers (SAMs) from functionalized porphyrin for bacteria trapping can lead to a highly sensitive sensor for bacteria detection. Different A₂BC-type porphyrin structures were synthesized and examined regarding their optical behavior. We achieved the synthesis of a porphyrin for SAM formation on a gold surface as electrode material. Two possible bio linkers were attached on the opposite meso-position of the porphyrin, which allows the porphyrin to react as a linker on the surface for bacteria trapping. Different porphyrin structures were attached to a gold surface, the SAM formation and the respective coverage was investigated.     

降钙素基因相关肽对大鼠离体心脏的作用及机理探讨

本文利用离体大鼠心脏标本,观察降钙素基因相关肽(CGRP)对心脏活动的影响,并用双脉冲技术测定左心房功能不应期(FRP)和α、β受体阻断剂,前列腺素合成抑制剂对CGRP对心脏活动影响。结果表明:CGRP对心脏具有明显的正性变力和正性变时作用,正性变力作用可能与β受体有关,正性变时作用可能与Na~+内流有关。     

硝苯地平和卡托普利对高血压患者血浆、唾液、尿液心钠素浓度的影响

目的探讨心钠素（ＡＮＰ）在高血压发病中的作用。方法５２例原发性高血压（ＥＨ）患者，随机分组，应用硝苯地平或卡托普利治疗２周前后，测定血浆、唾液、尿液ＡＮＰ含量的变化，并与健康组对照。结果治疗前患者血浆、唾液、尿液中ＡＮＰ均高于对照组（Ｐ＜０．０１）。治疗２周后，高血压组ＳＢＰ、ＤＢＰ和血、唾液、尿液中ＡＮＰ较治疗前明显降低（Ｐ＜０．０１），而治疗组间比较差异无显著性（Ｐ＞０．０５），且唾液和尿液中ＡＮＰ与血浆中浓度有同样变化趋势。结论硝苯地平和卡托普利可能是通过抑制ＡＮＰ的产生和释放的某个环节而发挥其降压效果的。     

B型利钠肽对慢性心力衰竭的诊断价值及与左心功能的关系

目的:探讨血浆B型利钠肽(BNP)水平在慢性心力衰竭(CHF)中的诊断价值,以及血浆BNP与CHF严重程度和左心室功能的关系.方法:对96例根据病史、体征、心脏X线胸片、实验室检查及对治疗反应等临床诊断为CHF的患者,就诊后24 h内取静脉血测定血浆BNP,并行超声心动图检查,分析血浆BNP与NYHA心功能分级及左心室射血分数之间的关系.结果:按照心功能分级,Ⅰ～Ⅳ级患者血浆BNP逐步增加(P＜0.001);左心室舒张末期内径≤55 mm的血浆BNP显著低于内径＞55mm者(P＜0.01);且左心室射血分数≤0.50的血浆BNP显著大于射血分数＞0.50者(P＜0.001).结论:血浆BNP水平提示能客观的反映心功能的情况,可作为一种简便快速的手段用于CHF的诊断及危险分层.     

盐酸氟桂利嗪治疗偏头痛的临床疗效及其对血浆降钙素基因相关肽水平的影响

目的分析盐酸氟桂利嗪治疗偏头痛的临床疗效及其对血浆降钙素基因相关肽(CGRP)水平的影响。方法选取2014年8月-2018年12月航天中心医院神经内科头痛门诊及住院病房收治的偏头痛患者45例,随访至第30天时根据随访日记将头痛发作频次≥3次/月的24例患者纳入研究并开始给予盐酸氟桂利嗪进行预防性治疗,连续治疗30 d。24例患者中5例未能完成试验、1例因出现哮喘而退出试验,最终共18例患者完成试验。比较18例患者用药前及用药30 d后头痛发作情况[包括头痛发作频次、头痛程度、视觉模拟评分法(VAS)评分及头痛持续时间],并记录用药期间不良反应发生情况;比较8例患者用药前及用药30 d后血浆CGRP水平。结果(1)18例患者用药前与用药30 d后头痛程度和头痛持续时间比较,差异无统计学意义(P>0.05);用药30 d后头痛发作频次和VAS评分低于用药前(P<0.05)。(2)8例患者用药30 d后血浆CGRP水平低于用药前(P<0.05)。(3)18例患者治疗期间均未出现明显不良反应。结论盐酸氟桂利嗪可有效降低偏头痛患者头痛发作频率及强度,其机制可能与降低血浆CGRP水平有关。     

Dimensional Accuracy and Surface Quality of AZ91D Magnesium Alloy Components after Precision Milling

This study investigates a precision milling process conducted with the use of conventional end mills and a standard CNC (Computer Numerical Control) machine tool. Milling tests were performed on samples of AZ91D magnesium alloy using TiB₂- and TiAlN-coated three-edge end mills measuring 16 mm in diameter. The following technological parameters were made variable: cutting speed, feed per tooth and axial depth of cut. The effects of precision milling were evaluated by analysing the scatter of dimension values obtained in successive tool passes. In addition to that, deviations from the assumed nominal depth as well as obtained ranges of dimension varation were analysed. The study also examined surface quality obtained in the precision milling process, based on the basic surface roughness parameters: Ra, Rz and RSm. Results have confirmed that the use of conventional cutting tools and a standard CNC machine tool makes it possible to manufacture components characterized by relatively small scatter of dimension values and high accuracy classes. Additionally, the results have shown that the type of tool coating and variations of individual technological parameters exert impact on the dimensional accuracy and surface quality obtained.