The application of percolation theory to the compaction of pharmaceutical powders

Based on the concepts of percolation theory the compaction process is interpreted as a site-bond percolation phenomenon. The combination of the Heckel equation with an equation derived earlier yields a simple relationship between the tensile strength σ_t, or the deformation hardness P and the relative density. This mathematical model is identical with the fundamental law of percolation theory i.e., X = s(p − p_c)^q with X= system property equivalent to tensile strength or deformation hardness, S = scaling factor, p = site occupation or bond formation probability corresponding to the relative density p,p_c = percolation threshold and critical exponent q = 1 according to percolation on a Bethe lattice. In the case of the tensile strength σ_t and the deformation hardness p, two percolation thresholds p_c(1) and p_c(2) corresponding to p_c(1) and p_c(2) could be identified. The relative density p_c(1) which is close to the relative poured or relative tapped density can be interpreted as a bond percolation threshold. The particles are bonded by weak interparticulate forces and form only loose compacts as used for filling of capsules. The relative density p_c(2) is the relative density where the first stable pharmaceutical compact is achieved which can no longer be disintegrated mechanically into its primary particles. It is of special interest that the above equation is also valid for the elastic modulus with the only percolation threshold p_c(1) = p_c(1).     

超声弹性成像技术联合血清学标志物预测2型糖尿病的应用价值

<正>多项研究表明,非酒精性脂肪性肝病患者(NAFLD)发生2型糖尿病(type 2 diabetes mellitus,T2DM)的风险是正常人的5倍^[1-3]。在T2DM患者中,NAFLD的患病率可高达70%^[4]。肝脏瞬时弹性成像技术(tran-sient elastography,TE)是近年来新兴的超声无创检查方法,主要基于超声信号在肝组织中传播受肝细胞中脂滴的影响而出现显著衰减的原理来评估肝脏脂肪性病变,     

剪切波弹性成像测量宫颈硬度的可重复性研究

目的：评价剪切波弹性成像（shear wave elastography,SWE）测量育龄期健康未育女性宫颈杨氏模量值的可重复性。方法：由同一名接受过SWE检测培训的高年资医师于同一天不同时间点,前后2次对100名处于育龄期但未育的健康女性宫颈行剪切波弹性成像,测量时选取宫颈4个位点：内口前唇（anterior lip of the inner mouth,IA）、内口后唇（posterior lip of the inner mouth,IP）、外口前唇（anterior lip of the outer mouth,EA）及外口后唇（posterior lip of the outer mouth,EP）,获取育龄期健康未育女性宫颈杨氏模量值。使用组内相关系数（interclass correlation coefficient,ICC）评价检查者内可重复性,同时绘制BlandAltman散点图评价测量一致性。结果：宫颈4个测量位点的前后2次测值均无统计学差异（P>0.05）;宫颈IA、EA、EP处杨氏模量值的组内相关系数分别为0.828、0.785、0.768,提示组内可重...     

Laser Peening Process and Its Impact on Materials Properties in Comparison with Shot Peening and Ultrasonic Impact Peening

The laser shock peening (LSP) process using a Q-switched pulsed laser beam for surface modification has been reviewed. The development of the LSP technique and its numerous advantages over the conventional shot peening (SP) such as better surface finish, higher depths of residual stress and uniform distribution of intensity were discussed. Similar comparison with ultrasonic impact peening (UIP)/ultrasonic shot peening (USP) was incorporated, when possible. The generation of shock waves, processing parameters, and characterization of LSP treated specimens were described. Special attention was given to the influence of LSP process parameters on residual stress profiles, material properties and structures. Based on the studies so far, more fundamental understanding is still needed when selecting optimized LSP processing parameters and substrate conditions. A summary of the parametric studies of LSP on different materials has been presented. Furthermore, enhancements in the surface micro and nanohardness, elastic modulus, tensile yield strength and refinement of microstructure which translates to increased fatigue life, fretting fatigue life, stress corrosion cracking (SCC) and corrosion resistance were addressed. However, research gaps related to the inconsistencies in the literature were identified. Current status, developments and challenges of the LSP technique were discussed.     

从“筋骨、痹痿、虚实、动静、刚柔”谈膝骨关节炎功能障碍的特点

膝骨关节炎(KOA)属于进展性骨关节病,其功能障碍主要表现为膝关节疼痛、僵硬、屈伸行走不利或受限,以及关节失稳、运动控制下降和本体感觉低下等。我国KOA患者众多,且还在逐年增加,引起的功能障碍严重影响着患者健康与生活质量,因此对其开展康复的研究与实践至关重要。中医康复着眼于功能,注重辨证康复,是我国康复医学的固有特色及优势。前期的研究基于KOA功能障碍的中医证候表现,本研究经大量文献梳理及多年临床实践,从“筋骨、痹痿、虚实、动静、刚柔”5个角度为切入点,提出KOA功能障碍具有“筋骨同病、痹痿并见、虚实错杂、动静失衡、刚柔失常”5个基本特点。鉴于KOA功能障碍具有早、中、晚三期的阶段性特点,在该病发生发展的不同阶段,其功能障碍在“筋骨、痹痿、虚实、动静、刚柔”之间的表现又各有所侧重。本研究从“筋骨同病、痹痿并见、虚实错杂、动静失衡、刚柔失常”5个方面分别阐释了KOA功能障碍的特点:“筋骨同病”侧重于病位,是KOA所致功能障碍的基本病机特征,贯穿于其发病的始终;“痹痿并见、虚实错杂”偏重病性,是KOA功能障碍的基本特点;“动静失衡”偏重病因,是引起KOA病情反复及加重的重要因素;“刚柔失常”则是兼具病状与病因,是膝关节失去“骨正筋柔”的表现方式,也是KOA功能障碍的重要特征。本研究旨在进一步完善KOA的中医康复理论,为其康复治疗提供参考。     

A logistic regression model for analyzing the relation between dentists' attitudes,behavior, and knowledge in oral radiology

The aim was to study the relation between risk attitude and knowledge in technical, patient-oriented, and organizationally related behavior within oral radiology. A questionnaire was mailed to 2000 randomly selected dentists listed in the register of the Swedish Dental Society, with a response rate of 69.3%. Regression analysis was used for analyzing the effects of the independent variables knowledge, risk attitude, continuing education in oral radiology, counties with specialists in oral radiology, type of practice, work experience, and sex on three categories of dependent variables: 1) technical behaviors: type of film, type of collimator, dose level, frequency of change of chemicals; 2) patient-oriented behaviors: use of patient protection barriers, strict indications for performing full-mouth X-ray examinations and bitewing radiography on new patients and recall patients; and 3) organizationally related behaviors: delegation of X-ray examinations to dental auxiliaries, influence on choice of collimator, influence on choice of film. Knowledge and education had strong direct effects for most of the dependent variables. The technical behaviors were mainly influenced by knowledge, education, and risk attitude, while organizationally related behaviors were influenced by type of practice and sex. The patient-oriented behaviors were influenced by a number of independent variables, such as education, type of practice, work experience, and sex. The present results indicate that both knowledge and the organizational context of dentists influence work.     

糖尿病强化治疗对大动脉硬化的影响

目的　观察瑞易宁联合络活喜强化治疗糖尿病对大动脉硬化的影响。　方法　糖尿病合并高血压6 3例 ,男 32例 ,女 31例 ,年龄 4 6岁～ 75岁 ,病情为慢性稳定期 ,除外心脑血管和糖尿病急症 ,随机分为A、B组。A组瑞易宁 5mg～ 2 0mgqd(餐前 )、络活喜 5mg～ 15mgqd联合治疗 ;B组美吡哒 5mg～ 10mgtid(餐前 )、长效心痛定 2 0mg～ 4 0mgq 12h联合治疗。两组根据病情可加用阿卡波糖、卡托普利和调脂药。疗程 6个月。观察治疗前和治疗后 3个月、6个月血糖、血脂、血压、主动脉内径和振幅的变化。　结果　A、B组在治疗前各项指标无差异 (P >0 0 5 )具有可比性。治疗后 6个月两组 :①空腹血糖≤ 6 1mmol L ,A、B组分别为 87 5 %对 73 3% (P <0 0 5 ) ;②非空腹血糖≤ 8 0mmol L ,为 81 3%对 6 6 7% (P <0 0 1) ;③血压≤ 130mmHg 80mmHg ,为 90 6 %对 73 3% (P <0 0 1) ;④血脂LDL C <2 6 0mmol L ,为 6 8 8%对 6 6 7% (P >0 0 5 ) ;⑤血压、脉压、主动脉内径和振幅的改善A组均优于B组。　结论　瑞易宁联合络活喜强化治疗能够平稳降糖、控压和改善糖尿病大动脉的硬化。     

Intrinsic foot muscle hardness is related to dynamic postural stability after landing in healthy young men

BackgroundThe human foot has competent mechanisms for supporting weight and adapting movement to various surfaces; in particular, the toe flexor muscles aid in supporting the foot arches and may be important contributors to postural stability. However, the role of intrinsic foot muscle morphology and structure in the postural control system remains unclear, and the relationship between them is not well known.Research questionAre intrinsic foot muscle morphology and toe flexor strength related to static and dynamic postural stability in healthy young men?.MethodsA total of 27 healthy men aged 19–27 years participated in this study. intrinsic foot muscle morphology included muscle hardness and thickness. Cross-sectional area was measured by ultrasonography at an ankle dorsiflexion angle of 0°. The hardness of the abductor hallucis (AbH), flexor hallucis brevis, and flexor digitorum brevis (FDB) muscles was measured using ultrasound real-time tissue elastography. Static postural stability during single-leg standing on a single force platform with closed eyes was assessed for the right leg. In the assessment of dynamic postural stability, the subjects jumped and landed on single-leg onto a force platform and the dynamic postural stability index (DPSI) was measured.ResultsFDB muscle thickness showed a positive correlation with anteroposterior stability index (APSI) (r = 0.398, p = 0.040). AbH muscle hardness was negatively correlated with APSI (r = −0.407, p = 0.035); whereas FDB muscle hardness was positively correlated with DPSI (r = 0.534, p = 0.004), vertical stability index (r = 0.545, p = 0.003), and maximum vertical ground reaction force (r = 0.447, p = 0.020). Multiple regression with forced entry revealed that only DPSI was significantly correlated with FDB muscle hardness (p = 0.003).SignificanceThe results indicated that intrinsic foot muscle hardness plays an important role in dynamic postural control among healthy young men, which may enable a more rapid muscular response to changes in condition during jump landing and better performance in balance tasks.     

New method to differentiate surface damping behavior and stress absorption capacities of common CAD/CAM restorative materials

ObjectivesTo assess energy dissipation capacities and surface damping abilities of different CAD/CAM restorative materials (CRMs) to characterize stress resistance during load peaks.MethodsUsing instrumented indentation testing (IIT), Martens hardness (HM) together with its elastic (η_IT) and plastic index (η_ITdis) and Leeb hardness (HLD) together with its deduced energy dissipation (HLD_dis) were determined for eight ceramic, eight composite, and four polymer-based materials as well as three metals. The results were compared to those of bovine enamel. Ten indentations per material were performed at room temperature (23 ± 1 °C) on two separate specimens (12.0 × 12.0 × 3.5 mm³) after water storage (24 h; 37.0 ± 1.0 °C). Hardness parameters were recorded, and data were analyzed with one-way MANOVA (Games-Howell post hoc tests, α = 0.05). Correlations between different parameters were tested (Pearson, α = 0.05).ResultsIndependently determined HLD_dis, and η_ITdis values substantiated different energy dissipation characteristics of CRM, whereby a strong correlation was observed for the two datasets (r = 0.956, p = 0.011). Ceramics had the significantly lowest values (p < 0.001) while both parameters revealed the highest surface damping effects for metals (p < 0.001), followed in both cases by bovine enamel. Energy dissipation of polymer and composite CRM was in between ceramics and bovine enamel (p < 0.001), whereas only for HLD_dis did both show no significant difference (p > 0.05).SignificancePromising new HLD_dis and η_ITdis data allow a reliable differentiation of energy dissipation and surface damping capacities of CRMs. Previously published rankings of edge chipping and loss tangent results were perfectly reproduced, especially by HLD_dis.