Statistical modeling for the optimal deposition of sputteredpiezoelectric films

The quality of sputtered-deposited piezoelectric films used for integrating bulk acoustic wave (BAW) and surface acoustic wave (SAW) devices with semiconductor circuitry depends on several deposition parameters, including substrate temperature, background pressure, gas composition, gas flow rate, and deposition rate. It is desirable to establish the fabrication process based on a selection of the controllable parameter values that optimizes the film quality. It is common practice to perform a number of deposition experiments by varying the controllable parameters to determine the optimal film growth conditions. The films are grown under a number of different conditions within this space and a response parameter related to film performance is measured. Then a multiple linear regression model is fit to the data. By optimizing the fitted response, the best growth conditions can be obtained. This approach is illustrated with data from recent work on the development of very high quality magnetron sputtered aluminum nitride (AlN) films whose acoustic characteristics are like those of epitaxial films grown at considerably higher substrate temperatures. Because the resource cost involved can be high, depending upon the number of deposition runs made, it is desirable to minimize the number of experiments and maximize the amount of information gained from them. A discussion is given on how the statistical theory of experimental design can be used to obtain this goal     

An in vivo comparative study of the e-polytetrafluoroethylene vascular prostheses: Vitaflon and Gore-Tex

A comparative study was performed in order to validate new Russian e-PTFE vascular prostheses Vitaflon (St. Petersburg, Russia). The Gore-Tex prostheses were chosen as a referential model. The prostheses were implanted in the venous and arterial positions in 13 dog experiments. After the implantation time was over a comprehensive histological and histochemical examination of excized specimens was performed. It was demonstrated that there is no difference in healing and functional properties between the two studied prostheses.     

Loratidine buccal films for allergic rhinitis: development and evaluation

The objective of this study was to develop a novel patient compliant buccoadhesive film capable of providing a prolonged protection against allergic symptoms. Polymeric buccoadhesive films of loratidine were prepared using hydroxypropylmethyl cellulose (HPMC)-E5 and K100 blend and Eudragit® NE 30D as retardant. Films were prepared using solvent-casting method. The developed films were evaluated for physical properties, hydration, mucoadhesion time, drug release, etc. All the prepared films exhibited excellent mechanical strength and uniform drug content. Increase in drug content did not influence the physicomechanical properties of the film. The mucoadhesive strength of films was significantly enhanced with increase in HPMC content. Increase in Eudragit® NE 30 D content in the film decreases the hydration, erosion and drug release, but enhances the mucoadhesion time. Furthermore, the release of loratidine from the prepared films followed Hixson–Crowell kinetics. Studies in healthy human volunteers using placebo films indicate that the prepared films possess prolonged mucoadhesion in-vivo, and this could potentially lead to clinically relevant drug delivery system.     

Experimental studies on the suitability of human mesothelial cells for seeding vascular prostheses: shear stress resistance in vitro

This investigation forms part of a study on the suitability of human omentum mesothelial cells (HOMES) as an alternative to endothelial cells (EC) for seeding vascular grafts. Isolated HOMES were grown in primary culture and characterized by their morphology (light microscopy and scanning electron microscopy (SEM)), as well as by fluorescence-activated cell sorting (FACS) and immunocytochemistry. The latter two methods showed cells which were positive for smooth muscle-type actin and cytokeratin, but negative for factor VIII-related antigen. HOMES were grown to confluence on glass with or without a fibronectin coating. Controlled shear stress was applied for up to 30 min using a plate and cone rheometer at 20 dynes/cm². These dynamic culture conditions led to loss of only occasional cells. The most marked alterations seen on SEM were some cell elongation, marked raising of the nucleus and loss of luminal cytoplasmic microvilli. Time-lapse video microscopy revealed that shear stress also increased the spreading capacity of some cells. Similar experiments with venous endothelial cells gave a shearing off of a confluent monolayer. This investigation shows the marked shear-stress resistance of HOMES, a pre-requisite for their use to seed vascular prostheses.     

Piezoelectric thin films: evaluation of electrical and electromechanical characteristics for MEMS devices

We present a new measurement method to characterize piezoelectric thin films utilizing a four-point bending setup. In combination with a single- or a double-beam laser interferometer, this setup allows the determination of the effective transverse and longitudinal piezoelectric coefficients e31,f and d33,f, respectively. Additionally, the dielectric coefficient and the large signal electrical polarization are measured to add further important characteristics of the film. These data are essential for piezoelectric thin film process specification and the design and qualification of microelectromechanical systems devices.     

Buccoadhesive films for once-a-day administration of rivastigmine: systematic formulation development and pharmacokinetic evaluation

Context: Rivastigmine, an anti-Alzheimer’s drug, suffers from major predicaments like low oral bioavailability, severe GI adverse effects related to rapid fluctuations in drug plasma levels, and high frequency of dosing.

Objective: The present investigation aims at developing buccoadhesive films capable of delivering the drug in vivo in a sustained manner. Augmentation of drug bioavailability by the avoidance of first-pass effect through the buccal route and reduction in GI side effects would be other key advantages of this system.

Methods: Buccoadhesive films of rivastigmine were systematically designed and evaluated for in vitro drug release, ex vivo buccal permeation and ex vivo buccoadhesive strength. Optimal composition of the polymer blends was rationally chosen using a central composite design and overlay plot. In vivo pharmacokinetic studies were carried out in rabbits, and attempts were made to establish in vitro/ in vivo correlations (IVIVC).

Results: Besides possessing the requisite drug release regulation, the optimized formulation exhibited excellent buccoadhesion, and buccal permeation. Pharmacokinetic studies indicated extension of plasma drug levels and level A of IVIVC was successfully established.

Discussion: Excellent buccal bioadhesion and transmucosal permeation, coupled with drug release control, ratify the potential of the optimized formulation to deliver the drug in a controlled and site-specific manner. Successful establishment of IVIVC substantiated the judicious choice of in vitro dissolution media for simulating the in vivo conditions.

Conclusion: Besides unraveling the polymer synergism, the study helped in developing an optimal once-a-day buccoadhesive drug delivery system exhibiting excellent trans-buccal permeation and buccoadhesive characteristics with improved bioavailability potential.     

Determination of optimal reactive sputtering conditions for the preparation of conductive transparent indium oxide films

The critical conditions for indium reactive sputtering under almost full oxidation are considered and the main details of this process are determined. The power coefficient of the sputtering velocity of the indium cathode and the power coefficient of the re-emission velocity of the oxygen from the growing indium oxide film surface have been determined experimentally. The influence of the sputtering conditions on stoichiometry, resistivity and optical transmission is investigated. It is shown that the critical conditions for reactive sputtering are close to the optimal conditions for obtaining highly conductive transparent indium oxide films. The method for calculating the values of the critical conditions for indium reactive sputtering is given.     

Preparation and endothelialization of decellularised vascular scaffold for tissue-engineered blood vessel

The proliferation of cells on the decellularised tissues fixed by chemical crosslinking agent is retarded for cytotoxicity of crosslinked tissues. To overcome this disadvantage, we prepared the decellularised vascular scaffold through fixing the porcine thoracic arteries with 40mL/L ethylene glycol diglycidyl ether (EGDE), and reduced the cytotoxicity of this scaffold by treating it with lysine and coating it with type I collagen, finally endothelialized it in vitro. The EGDE-fixed porcine thoracic arteries were examined morphologically. The fixation index determination and the biomechanics test were also performed. Human umbilical vein endothelial cells (HUVECs) were seeded on the type I collagen-coated surface of different modified vascular tissues (fixed with glutaraldehyde or EGDE or EGDE + lysine), and the growths of HUVECs on the specimens were demonstrated by means of MTT test. Finally, HUVECs were seeded on the luminal surface of the modified porcine vascular scaffolds which were respectively treated in the same manner described above, and then cultured for 7 days. On the seventh day, the HUVECs on the specimens were examined by means of light microscopy, scanning electron microscopy and transmission electron microscopy (TEM). The antigenicity of the vascular tissues can be diminished by EGDE through getting rid of cell in the vascular tissues or reducing the level of free amino groups in the vascular tissues. In this study, it was also found that the EGDE-fixed porcine vascular tissues appeared similar to the native porcine vascular tissues in color and mechanical properties. After treated by 2% lysine and coated with type I collagen, the EGDE-fixed porcine vascular tissues were characterized by low cytotoxicity and good cytocompatible. The HUVECs can proliferate well on the modified vascular tissues, and easily make it endothelialized. The results showed that the modified porcine vascular scaffolds should be a promising material for fabricating scaffold of tissue-engineered blood vessel.     

Development and evaluation of rapidly dissolving buccal films of naftopidil: in vitro and in vivo evaluation

Abstract

Objectives: Development and evaluation of rapidly dissolving film for intra-oral administration of naftopidil.

Significance: Formulation of naftopidil in the form of rapidly dissolving buccal film can eliminate the dissolution problem of naftopidil and provide a greater chance for direct absorption into the systemic circulation bypassing the presystemic metabolism. This can improve the oral bioavailability. In addition, this film guarantees patient compliance and is suitable for geriatric patients.

Methods: Rapidly dissolving film utilized hydroxypropyl methylcellulose E5 and polyvinylpyrrolidone K30 as the main components. The drug was loaded in pure form or after co-grinding with citric and/or tartaric acid. A solution of naftopidil in plurol oleique, labrasol, and tween 80 self-microemulsifying drug delivery systems (SMEDDS) was also loaded. The interactions of the drug with the excipients were monitored using thermal analysis, Fourier transform infrared spectroscopy, and X-ray diffraction. Naftopidil dissolution was monitored and selected films were used to assess the bioavailability after buccal administration to rabbit. Unprocessed drug suspension was administered orally and used as a reference.

Results: Incorporation of naftopidil in the film developed a new crystalline structure. The crystallinity of drug was abolished in the presence of organic acids or SMEDDS. The rapidly dissolving films showed fast liberation of the drug irrespective to the composition. Those films enhanced the bioavailability of naftopidil compared to orally administered suspension with SMEDDS containing film being superior.

Conclusion: The study introduced rapidly dissolving buccal film for enhanced dissolution and bioavailability of naftopidil.     

Signal processing support for the evaluation of blood toxicoxidation activity

The problem addressed in this paper is related to numerical correction of spectrometric data aimed at enhancing the quality of interpretation of the spectrum of mixed substances. A digital signal processing method is proposed to eliminate an interfering absorption spectrum and evaluate the blood toxic oxidation activity. The effectiveness of the proposed method is demonstrated using synthetic data and real-world data acquired in biophysical laboratory     

环氧树脂钢铅钢粘接工艺优化程度评价方法

为了改善环氧树脂钢-铅-钢粘接件的粘接可靠性,提高粘接性能,采取一套比较全面的综合评判方法,从粘接强度及其离散性、粘接的胶层粘附率、粘接断面的微观形貌及其表面分析五个角度的综合分析、评价钢-铅-钢环氧树脂粘接件的粘接工艺的优化程度.通过对粘接面的表面处理来改进粘接工艺,将试样的平均粘接强度从原来的4.2 MPa提高到10.9 MPa,同时强度离散性参数从19%下降到3.3%,总体胶层粘附率参数从50%提高到76%～97%,微观形貌下表面粗糙度有所改善,表面分析表明铅合金与环氧树脂胶层结合较为紧密.综合评判方法验证了改进后的粘接工艺具有较高的优化程度,该评价方法对评价粘接工艺是否优化具有较好的效果.     

Development of an identification system for biaxially oriented polymer films based on the degree of their transverse extension

An expression has been developed that generalizes three basic geometric schemes of film deformation (axial, planar, and biaxial extension) and also all intermediate schemes. The system of quantitative identification of nonuniformly biaxially oriented films according to their transverse extension has been tested on six different film types.     

Statistical evaluation of lightning-related failures for the optimal location of surge arresters on the power networks

Direct lightning strokes cause unscheduled supply interruptions in power systems because of a failure of the insulation. Metal oxide surge arresters, as a proper protective device, have been widely adopted in power systems to reduce lightning initiated flashovers and, hence, increase the power quality and reliability of the systems. Based on a genetic algorithm approach, a cost effective solution is described to find the optimum location of surge arresters on a power network in order to minimise the global risk of the network, and to improve its reliability. A statistical approach to evaluate lightning failures has been introduced and an optimisation procedure developed to analyse the network in order to satisfy the power utility requirement for a specific value of risk and/or line performance with a minimum set of arresters, that is, at minimum cost. Not only the insulation flashover but also the failure of the arrester can affect the reliability of power systems. Therefore, both the failure of the insulation and that of the arrester are considered in the proposed method.     

纳米TiO_2改性丝素膜制备工艺优化及其性能研究

设计正交试验法并采用溶胶一凝胶法制备了性能良好纳米TiO2溶胶丝素复合膜,并利用SEM、FTIR及XRD等分析手段对丝素膜进行表征,结果表明:纳米TiO2均匀分散在丝素膜中,纳米TiO2与丝素分子相互作用,导致丝素分子的重排,并诱导丝素构象从Silk Ⅰ向SilkⅡ转变.     

Multicriteria evaluation and optimization of the ultrasonic sealing performance based on design of experiments and response surface methodology

Proper closure is an essential packaging quality aspect and can, amongst others, be achieved with ultrasonic sealing. The ultrasonic sealing performance depends on the film type, and the seal settings, such as seal time, applied force and ultrasonic amplitude. Because these parameters are less intuitive than heat seal parameters and optimal settings are undefined for many films, this work presents an efficient approach to evaluate the effect of these settings on the ultrasonic sealing performance. An experimental design defines the experiments to perform. A response surface methodology is then used to model the relation between seal settings and sealing performance. Based on these models, the seal settings are optimized. As there are several criteria to express sealing performance, single‐criteria and multicriteria optimizations are described. The approach was illustrated for a polyethylene terephthalate/linear low‐density polyethylene‐C4 film. The seal settings were optimized to obtain high seal strength, limited ultrasonic horn displacement, and low seal energy. The optimum settings were 0.1 seconds (seal time), 4.32 N/mm (force), and 28.75 μm (amplitude). The predicted optimum strength, horn displacement, and energy were 2.32 N/mm, 40 μm, and 11.66 J, respectively. Besides the optimum, the seal window is also of interest. A broad seal window ensures sufficient seal strength for a wide range of settings. For the polyethylene terephthalate/linear low‐density polyethylene‐C4 film, a strength of ≥90% of the optimum was obtained for 39% of the input combinations within the design space. The presented approach is widely applicable (other films and sealing processes) since it is flexible in the input parameters, design, and responses.     

Fast dissolving electrospun polymeric films of anti-diabetic drug repaglinide: formulation and evaluation

Abstract

Objective: Repaglinide is a well-known FDA approved drug from category of meglitinide; used for the treatment of diabetes. However, its use is limited because of its poor water solubility which leads to erratic drug absorption. Present work focuses on formulation and evaluation of polyvinyl alcohol (PVA)-polyvinyl pyrrolidone (PVP) nanofibers to counter this problem of poor water solubility.

Significance: Prepared nanofibers with hydrophilic polymers were expected to tackle the problem of poor water solubility.

Methods: Nanofibers were prepared by electrospinning technique with the optimization of parameters affecting final product. Further prepared formulation was characterized using various techniques.

Results: Successful development of drug loaded nanofibers was commenced utilizing electrospinning technique. Further casted film of same polymeric blend was prepared and compared with nanofibers. Optimized nanofibers showed an average diameter of 600–800?nm with smooth surface morphology. Prepared nanofibers and casted film was analyzed in terms of surface morphology, mechanical strength, solid state of drug present, effects of hydrogen bond formation and drug release profile. Results from the glucose tolerance test suggested both the formulations to be having better control over glucose levels as compared to free drug.

Conclusion: Overall developed nanofibers presented themselves to be potential drug delivery candidates for drugs having poor water solubility.     

堆石坝坝型优选模型及评价方法研究

坝型优选属于多因素、多方案的复杂决策问题,不仅需要经验丰富的熟悉实际工程情况的专家,而且需要运用客观的分析决策技术。本文综合分析堆石坝坝型选择中的各种影响因素,建立了坝型方案优选的递阶层次结构模型。考虑了层次分析法和熵权法对权重确定的不足,将两者结合起来计算综合权重,并运用TOPSIS法对模型进行求解计算,最终确定优选方案。实际应用结果表明,该方法计算简便、结果可靠,能够为堆石坝坝型优选提供科学的决策依据。     

A model for the evaluation of indentation crack arrest fracture toughness of supported films

A simple model is proposed for the evaluation of crack-arrest fracture toughness K _Ic0 of thin films by Vickers indentation. This approach applies to films thinner than the penetration depth of the Vickers indenter. The model equations are provided in closed form, even though they are so complex that they must be integrated numerically in practical applications. The problem of the evaluation of K _Ic0 for thin films and substrates is derived in general form and applied to three cases: (i) evaluation of K _Ic0 for the film in the case that the depth of the crack in the film is smaller than the film thickness, (ii) evaluation of K _Ic0 for the film in the case that the crack emanating from the film either crosses the film/substrate interface or is stopped by it, (iii) evaluation of K _Ic0 for the substrate in the case that the crack emanating from the film crosses the film/substrate interface. The model was tested with original and literature experimental data: (i) revision K _Ic0 values of electroless Ni-P thin films were re-evaluated, (ii) K _Ic0 of electroless Ni-P thin films of various thickness with various loads were measured (original data) and computed, (iii) K _Ic0 of electroless Ni-P substrates coated with electrodeposited Au-Cu were measured (original data) and computed.     

淀粉/PVA膜在血浆模拟液及唾液模拟液中的体外降解行为及相关体外生物相容性评价

通过熔融浇注法制备出一系列厚度在0.05 mm～0.10 mm的淀粉/聚乙烯醇（PVA）（SP）薄膜。研究了薄膜在血浆（SBF）及唾液模拟液（SSF）中的降解行为,分析了降解过程中力学性能、失重率、溶胀度、热性能以及表面形态的变化。研究结果表明,膜在30天的降解过程中能够维持良好的尺寸稳定性和一定的力学强度。通过细胞毒性、细胞贴壁及溶血试验表征了膜的体外生物相容性。结果表明,SP膜具有良好的细胞和血液相容性。所有测试结果证明,SP薄膜是一种应用于诱导组织再生薄膜的潜在材料。