Evaluation of polycaprolactone − poly‐D,L‐lactide copolymer as biomaterial for breast tissue engineering

The potential of the copolymer polycaprolactone‐co‐ poly‐d ,l ‐lactic acid (PCLLA ) as a biomaterial for scaffold‐based therapy for breast tissue engineering applications was assessed. First, the synthesized PCLLA was evaluated for its processability by means of additive manufacturing (AM ). We found that the synthesized PCLLA could be fabricated into scaffolds with an overall gross morphology and porosity similar to that of polycaprolactone. The PCLLA scaffolds possessed a compressive Young's modulus (ca 46 kPa ) similar to that of native breast (0.5 ? 25 kPa ), but lacked thermal stability and underwent thermal degradation during the fabrication process. The PCLLA scaffolds underwent rapid degradation in vitro which was characterized by loss of the scaffolds' mechanical integrity and a drastic decrease in mass‐average molar mass (M _w) and number‐average molar mass (M _n) after 4 weeks of immersion in phosphate buffer solution maintained at 37 °C. The tin‐catalysed PCLLA scaffold was also found to have cytotoxic effects on cells. Although the initial mechanical properties of the PCLLA scaffolds generally showed potential for applications in breast tissue regeneration, the thermal stability of the copolymer for AM processes, biocompatibility towards cells and degradation rate is not satisfactory at this stage. Therefore, we conclude that research efforts should be geared towards fine‐tuning the copolymer synthesizing methods. © 2016 Society of Chemical Industry     

Remote-sensing-based study of impact of a rock avalanche on North Terong Glacier in Karakorum Himalaya

ABSTRACT

In this article, we report the results of a study on occurrence of a mass-movement event classified as ‘rock avalanche’ over the North Terong glacier (a tributary of the Siachen Glacier in the Nubra Valley), using multi-date remote-sensing data of Landsat Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Operational Land Imager (OLI) and its effects on glacier-surface velocity. Normalized cross-correlation image matching method for displacement measurements at sub-pixel level using Computer Imaging Analysis Software (CIAS), an add-on module of Environment for Visualizing Images (ENVI) software, was used to map changes in the position of debris-deposits of the rock avalanche and assess variations in glacier-surface velocities. Well-defined debris margins gave positions of debris on different dates. Study indicated that this rock avalanche must have occurred between 21 April 2000 and 8 May 2000 (possibly on 3 or 4 May). It induced a kinematic wave or a ‘mini-surge’ in the glacier with its surface velocity showing almost twofold increase in post-event period.     

嵌入式视频处理系统领域的FPGA验证

参与消费电子细分市场,会带来许多优势。尽管如此,该细分市场的设计团队仍将面临急剧收缩的上市时间窗口。因此,基于FPGA的设计已经演变成为许多系统体系结构设计者的首选。同时,人们对消费品中的多媒体功能的需求日益增多,这使得DSP和流传输接口成为许多嵌入式产品中必备的部件。几家FPGA厂商开发了带有DSP核心与流传输接口的FPGA,它们在技术和复杂度上均足以应对最近这些设计要求。     

Detection of Chlorophenolic Compounds in Bleaching Effluents of Chemical Pulps

Laboratory bleaching effluents from the chlorination and caustic extraction stages of mixed wood kraft pulp processing have been analysed both qualitatively and quantitatively for various chlorophenolics by using GC.A number of chlorinated derivaties of phenols,catechols,guaiacols and syringaldehydes have been detected and their concentrations are estimated.The results are compared with that of different agriculture residue / hardwood pulps,which were reported in literature.The concentrations of various compounds detected have also been compared with their reported 96LC50 values.     

Bacterial population changes in hospital effluent treatment plant in central India

Hospital effluent with its high content of multidrug resistant (MDR) enterobacteria and the presence of enteric pathogens could pose a grave problem for the community. It was planned at our tertiary care hospital in central India to study the population changes at various steps of effluent treatment plant (ETP) like collection, aeration, clarification, liquid sludge, dried sludge, high-pressure filter and treated wastewater. The study included viable bacterial counts, coliform counts, staphylococcal, enterococcal, Pseudomonas and multiple drug resistant (MDR) gram negative bacterial counts in the different stages of ETP. In order to study the distribution of bacteria as free floating in liquid and adherent to suspended particles, enumeration of the bacteria in the filterate and the sediment was also carried out. The effluent input showed 55% of the 8.6 x 10(6)/ml bacteria as coliforms and E. coli which was a typical of fecal flora. The prevalence of MDR coliforms was 0.26%. The substantial reduction (> 3log) was seen for the effluent coming from the clarifier. The bulk of the bacteria in the hospital effluent remains firmly adhered to solid particles; aeration and clarification removes bulk of the bacteria by physical processes like flocculation. The treated liquid effluent still contains sizeable loads of MDR bacteria and inactivation by procedure such as chlorination is required. The bacteria get concentrated in sludge and a greater concentration of chlorine is required for decontamination.     

Salt-and-pepper noise removal by adaptive median-based lifting filter using second-generation wavelets

In this paper, we propose a novel adaptive median-based lifting filter for image de-noising which has been corrupted by homogeneous salt and pepper noise. The median-based lifting filter removes the noise of the input image by calculating the median of the neighboring significant pixels. The algorithm for image noise removal uses the lifting scheme of the second-generation wavelets in conjunction with the proposed adaptive median-based lifting filter. The experimental results demonstrate the efficiency of the proposed method. The proposed algorithm is compared with all the basic filters, and it is found that our method outperforms many other algorithms and it can remove salt and pepper noise with a noise level as high as 90%. The algorithm works exceedingly well for all levels of noise, as illustrated in terms of peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM) measures.     

Identification of Fouling Mechanism During Ultrafiltration of Stevia Extract

Stevioside is one of the naturally occurring sweetener, which can be widely applied in food, drinks, medicine, and daily chemicals. Membrane separation has potential application in clarification of stevioside from pretreated stevia extract by ultrafiltration. In the present study, namely 5-, 10-, 30-, and 100-kDa molecular weight cutoff membranes have been used. Quantification of membrane fouling during ultrafiltration is essential for improving the efficiency of such filtration systems. A systematic analysis was carried out to identify the prevailing mechanism of membrane fouling using a batch unstirred filtration cell. It was observed that the flux decline phenomenon was governed by cake filtration in almost all the membranes. For 100 kDa membrane, both internal pore blocking and cake filtration are equally important. Resistance in series analysis shows that the cake resistance is several orders of magnitude higher than the membrane resistance. The cake resistance is almost independent of transmembrane pressure drop, which indicates the incompressible nature of the cake. A response surface analysis was carried out to quantify the development of cake resistance with time during ultrafiltration of various membranes. Quality parameters show that the 30-kDa membrane is better suited for clarification purposes. Identification of the fouling mechanism would aid in the process of design and scaling up of such clarification setup in future.     

A novel approach for evaluation of polymeric interface materials for chemical sensors using alternate indirect methods

The heart of a chemical sensor based on bulk or surface acoustic wave devices is a polymer‐coated piezoelectric substrate that selectively sorbs and concentrates the target analyte vapors. The development of such sensors often necessitates the screening and evaluation of suitable polymeric interface materials meeting the specified sensitivity and selectivity toward the analytes of interest. The magnitude and dynamics of sorption–desorption of the vapors in the polymer and the extent of polymer–vapor interactions largely determine the performance of a sensor. The standard protocol used for the purpose is rather tedious, involving the generation and calibration of individual analyte vapors, with stringent control on temperature, humidity, and test parameters. This article outlines four different alternative techniques based on mass uptake of the analyte vapors, on its partitioning in polymers, or both, which in combination can determine the characteristics of an interface material used for coating a piezoelectric substrate in acoustic wave‐based chemical sensors. These methods were applied to poly(ethylene maleate), a representative interface material. The analytes ranged from volatile organic chemicals to sarin—a chemical warfare agent—and its simulant, dimethyl methylphosphonate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3428–3432, 2004     

Comparison of Biocorrosion due to Desulfovibrio desulfuricans and Desulfotomaculum nigrificans Bacteria

One observes several species of sulfate-reducing bacteria in nature. Presence of these species in a media may cause microbial influenced corrosion (MIC) of materials differently. To investigate this aspect of MIC, corrosion tests were performed on three types of stainless steels. The tests were done in modified Baar’s media inoculated separately by the two species of SRB namely Desulfovibrio desulfuricans (DD) and Desulfotomaculum nigrificans (DN). Electrochemical and immersion tests were performed to assess the extent of uniform and localized corrosion of these steels. Biofilms formed on the corroded samples were analyzed for estimating various components of its extracellular polymeric substances. Hydrogenase enzyme of these bacteria was tested to determine its nature and activity. Higher degree of corrosivity was observed in case of media inoculated with DD as compared to DN. More active nature of hydrogenase enzyme, its location in the periplasmic phase in DD and higher fraction of carbohydrate in biofilm formed due to DD have been suggested to be responsible for higher degree of corrosivity caused by them.     

Dexamethasone eluting biodegradable polymeric matrix coated stent for intravascular drug delivery

Targeted drug delivery systems are used to minimize the adverse effects of the pharmaceutical agents while maintaining the high local drug concentrations. To minimize post-angioplasty complications like tissue hyperplasia and related restenotic events, cardiovascular stents coated with anti-inflammatory, anti-proliferative agents have been proposed. The efficacy and toxicity of local therapeutics depends upon drug release kinetics which will further decide drug deposition, distribution, and retention at the target site. Drug eluting stents (DES) presently possesses clinical importance as an alternative to coronary artery bypass grafting due to ease of procedure and comparable safety and efficacy. This paper focuses on preparation and evaluation of controlled drug release biodegradable systems for stent base drug delivery providing insight of the drug elution mechanism which ultimately governs release kinetics. Multiple layers of dexamethasone-biodegradable polymers were successfully spray coated on Co–Cr alloy L605 metallic stents by modified air brush technique. In vitro drug elution data acquired by high performance liquid chromatography (HPLC) revealed that release of dexamethasone can be modulated up to 3 weeks by optimized use of blends of biodegradable poly-l-lactide-co-caprolactone and polyvinyl pyrrolidone. Surface investigation by scanning electron microscopy (SEM) represented smooth surface finish without any irregularities suggesting the efficacy of utilization of optimal coating parameters for multiple layer coating.