Proton Exchange Membranes by Radiation-Induced Graft Copolymerization of Monomers into Teflon-FEP Films

A state-of-the-art in radiation-induced graft copolymerization of styrene and acrylic acid monomers into Teflon-FEP films is presented with a view to develop proton exchange membranes for various applications. This process offers an easy control over the composition of a membrane by careful variation in radiation dose, dose rate, monomer concentration, and temperature of the grafting reaction. By varying the nature and the amount of the grafted content, it is possible to achieve a membrane with desired physico-chemical properties. In this paper, a correlation among the degree of grafting, structural changes, and properties of graft copolymer membranes is discussed

Radiation grafted membranes

The development of proton-exchange membranes for fuel cells has generated global interest in order to have a potential source of power for stationary and portable applications. The membrane is the heart of a fuel cell and the performance of a fuel cell depends largely on the physico-chemical nature of the membrane and its stability in the hostile environment of hydrogen and oxygen at elevated temperatures. Efforts are being made to develop membranes that are similar to commercial Nafion membranes in performance and are available at an affordable price. The radiation grafting of styrene and its derivatives onto existing polymer films and subsequent sulfonation of the grafted films has been an attractive route for developing these membranes with requiredchemistry and properties. The process of radiation grafting offers enormous possibilities for design of the polymer architecture by careful variation of the irradiation and the grafting conditions. A wide range of crosslinkers are available, which introduce stability to the membrane during its operation in fuel cells. Crosslinking of the base polymer prior to grafting has also been an attractive means of obtaining membranes with better performance. A systematic presentation is made of the grafting process into different polymers,the physical properties of the resultant membranes, and the fuel cell application of these membranes

Native extracellular matrix: a new scaffolding platform for repair of damaged muscle

Effective clinical treatments for volumetric muscle loss resulting from traumatic injury or resection of a large amount of muscle mass are not available to date. Tissue engineering may represent an alternative treatment approach. Decellularization of tissues and whole organs is a recently introduced platform technology for creating scaffolding materials for tissue engineering and regenerative medicine. The muscle stem cell niche is composed of a three-dimensional architecture of fibrous proteins, proteoglycans, and glycosaminoglycans, synthesized by the resident cells that form an intricate extracellular matrix (ECM) network in equilibrium with the surrounding cells and growth factors. A consistent body of evidence indicates that ECM proteins regulate stem cell differentiation and renewal and are highly relevant to tissue engineering applications. The ECM also provides a supportive medium for blood or lymphatic vessels and for nerves. Thus, the ECM is the nature's ideal biological scaffold material. ECM-based bioscaffolds can be recellularized to create potentially functional constructs as a regenerative medicine strategy for organ replacement or tissue repopulation. This article reviews current strategies for the repair of damaged muscle using bioscaffolds obtained from animal ECM by decellularization of small intestinal submucosa (SIS), urinary bladder mucosa (UB), and skeletal muscle, and proposes some innovative approaches for the application of such strategies in the clinical setting

Micrometer-sized negative-ion accelerator based on ultrashort laser pulse interaction with transparent solids

We report here energetic (>100keV) negative hydrogen ions (H−) generated in the interaction of moderately intense (1018Wcm−2) ultrashort laser pulses (45 fs) with transparent hydrogen containing solid targets. An unambiguous and consistent detection of negative hydrogen ions, with a flux of 8×1011H− ions/sr, has been observed in every single laser shot, using a Thomson parabola ion spectrograph. Simple estimates based on charge transfer cross sections match well with experimental observations. Our method offers the implementation of an intense, ultrashort laser based negative-ion source at a higher repetition rate, which can be important for various applications

Spatial Organization and Molecular Correlation of Tumor-Infiltrating Lymphocytes Using Deep Learning on Pathology Images

Beyond sample curation and basic pathologic characterization, the digitized H&E-stained images of TCGA samples remain underutilized. To highlight this resource, we present mappings of tumorinfiltrating lymphocytes (TILs) based on H&E images from 13 TCGA tumor types. These TIL maps are derived through computational staining using a convolutional neural network trained to classify patches of images. Affinity propagation revealed local spatial structure in TIL patterns and correlation with overall survival. TIL map structural patterns were grouped using standard histopathological parameters. These patterns are enriched in particular T cell subpopulations derived from molecular measures. TIL densities and spatial structure were differentially enriched among tumor types, immune subtypes, and tumor molecular subtypes, implying that spatial infiltrate state could reflect particular tumor cell aberration states. Obtaining spatial lymphocytic patterns linked to the rich genomic characterization of TCGA samples demonstrates one use for the TCGA image archives with insights into the tumor-immune microenvironment

Development and structural evaluation of poly(lactic acid) based knitted scaffold for human urinary bladder reconstruction

115-121 Knitted scaffolds of poly(lactic acid) (PLA) filament spun by dry-jet-wet technique have been developed for human urinary bladder reconstruction. Three different types of samples are prepared by varying the number of ply in the PLA yarn. Flexural rigidity of PLA monofilament is found to be dependent on draw ratio. It decreases from 16.22×10-7 kg m4 to 2.74×10-7 kg m4 as the draw ratio increases from 2 to 10. The performance of the developed structures is evaluated by ball bursting technique on a tensile tester. It is observed that the knitted structure with 8 ply yarn has bursting strength of 53.7 kg with 2.5 cm extension. The cyclic loading of knitted structure has been carried out at the load half of the bursting loads. It is found that the structure gets permanently set after 5 cycles of loading. Porosity of the knitted fabric is determined by ratio of voids volume to that of the total volume of knitted fabric. The knitted structure with 8 ply yarn has 80% porosity. Pore size of the knitted structures is determined by optical microscope. The in vitro degradation of the PLA knittings at different pH (4.6, 7.4 and 8.0) has been carried out for a period of 20 weeks. The surface morphology was studied by scanning electron microscopy. A severe degradation of sample is observed at pH 4.6. </smarttagtype

Taurine: A potential mediator for periodontal therapy

Taurine or 2-aminoethanesulfonic has many fundamental biological roles such as conjugation of bile acids, antioxidation, osmoregulation, membrane stabilization, and modulation of calcium signaling. It is essential for cardiovascular function and development and function of the skeletal muscle, the retina, and the central nervous system. Functions of taurine include osmoregulation; membrane stabilization; modulation of calcium levels; and antioxidation, antiapoptotic, anti-inflammatory, and antilipid activities. Taurine was first discovered as a component of ox (Bos taurus, from which its name is derived) bile in 1827; it had taken over a century before insights into its physiological functions were made. The present review throws light on the multifactorial properties of taurine and its potential to be used in periodontal therapy

Water management in alpha methyl styrene-butyl acrylate grafted and sulfonated PEEK membranes

176-181Radiation grafted and sulphonated PEEK (poly ether ether ketone) membranes have been analyzed for water management within the matrix. Grafting is done using alpha methyl styrene-butyl acrylate (AMS/BA) mixture. Membranes exhibit enhanced water content with the increasing ionic content due to higher hydrophilicity. However, the water/ionic site ratio increases significantly with the increasing graft levels. The ionic mobility also increases with increasing graft levels. It is stated that the water management within the hydrophilic membrane matrix plays a key role and is responsible for the high proton mobility at higher graft levels in the membrane. This, in turn, is governed by the physiochemical changes taking place in membranes due to the grafting and sulfonation process. A correlation of the higher water/ionic site ratio arising out of the structural changes in the proton exchange membranes may be developed by radiation grafting of AMS/BA followed by sulfonation