Nicholas A. Peppas

Bio: Nicholas A. Peppas is an academic researcher from University of Texas at Austin. The author has contributed to research in topics: Self-healing hydrogels & Drug delivery. The author has an hindex of 141, co-authored 825 publications receiving 90533 citations. Previous affiliations of Nicholas A. Peppas include National Technical University & University of Texas System.

Anomalous penetrant transport in glassy polymers. VII. Overshoots in cyclohexane uptake in crosslinked polystyrene.

Abstract: Transport of liquid cyclohexane through well characterized, initially glassy, crosslinked polystyrene slabs was investigated as a function of time at 20, 30, 40, and 50 ° C. The samples used were produced by bulk polymerization of styrene and divinyl benzene using benzoyl peroxide as an initiator at 90 ° C for 48 hrs. The samples tested had initial crosslinking ratios, X, between 0.005 and 0.0250 mol DVB/mol styrene, their thickness varied from 0.025 to 0.180 cm, and the aspect ratio was maintained above 10 to achieve one-dimensional transport. A cyclohexane uptake overshoot was observed as a function of time. This overshoot was analyzed as a function of crosslinking ratio and geometric characteristics of the samples and it was attributed to molecular changes of polystyrene during swelling.

Cellular evaluation of synthesized insulin/transferrin bioconjugates for oral insulin delivery using intelligent complexation hydrogels.

Abstract: Insulin transport across the epithelial cell layer in the small intestine was studied using insulin/transferrin conjugates with and without the presence of P(MAA-g-EG) microparticles in contact with a co-culture of Caco-2/HT29-MTX cells. The insulin/transferrin conjugate was shown to increase transport relative to pure insulin by a factor of 7, achieving an apparent permeability of 37 x 10 9 cm · s -1 . The presence of P(MAA-g-EG) microparticles increased conjugate transport by a factor of 14 times relative to insulin, achieving an apparent permeability of 72.8 x 10 9 cm · s -1 . The presence of the microparticles in solution was found to improve conjugate transport by nearly 100% with little to no change in cell monolayer integrity.

Swelling behavior of temperature- and pH-sensitive block terpolymers for drug delivery

Abstract: Hydrogels prepared by block terpolymerization of N-isopropylacrylamide (NIPAAm), acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) exhibit significant temperature sensitivity due to the block structure of the NIPAAm moiety, even at concentrations as low as 10 mol%. pH-Sensitivity was also observed due to the ionizable AA component. The swelling ratio dependence on temperature is significantly more prominent for block terpolymers than for the corresponding random terpolymers.

An Investigation of Polymer Diffusion in Hydrogel Laminates Using Near-Field FTIR Microscopy

Abstract: The role of diffusion in gel/gel adhesion was examined by near-field FTIR microscopy. Using a near-field FTIR microscopy technique, compositional maps were obtained with improved spatial resolution and enhanced signal to noise ratio. With this technique, the resolution was enhanced by about a factor of 5. Polymer chain diffusion across a gel/gel interface was a substantial mechanism of adhesion. Diffusion of poly(ethylene glycol) (PEG) free chains across poly(acrylic acid) (PAA) gels was investigated. The diffusivity of PEG was on the order of 10-8 to 10-9 cm2/s for these swollen polymer gels. PEG diffusivity in PAA gels scaled to M-0.41. This was similar to values reported for PEG diffusion in aqueous solution.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Harrison's Principles of Internal Medicine

Abstract: The 11th edition of Harrison's Principles of Internal Medicine welcomes Anthony Fauci to its editorial staff, in addition to more than 85 new contributors. While the organization of the book is similar to previous editions, major emphasis has been placed on disorders that affect multiple organ systems. Important advances in genetics, immunology, and oncology are emphasized. Many chapters of the book have been rewritten and describe major advances in internal medicine. Subjects that received only a paragraph or two of attention in previous editions are now covered in entire chapters. Among the chapters that have been extensively revised are the chapters on infections in the compromised host, on skin rashes in infections, on many of the viral infections, including cytomegalovirus and Epstein-Barr virus, on sexually transmitted diseases, on diabetes mellitus, on disorders of bone and mineral metabolism, and on lymphadenopathy and splenomegaly. The major revisions in these chapters and many

Understanding biophysicochemical interactions at the nano–bio interface

Abstract: Rapid growth in nanotechnology is increasing the likelihood of engineered nanomaterials coming into contact with humans and the environment. Nanoparticles interacting with proteins, membranes, cells, DNA and organelles establish a series of nanoparticle/biological interfaces that depend on colloidal forces as well as dynamic biophysicochemical interactions. These interactions lead to the formation of protein coronas, particle wrapping, intracellular uptake and biocatalytic processes that could have biocompatible or bioadverse outcomes. For their part, the biomolecules may induce phase transformations, free energy releases, restructuring and dissolution at the nanomaterial surface. Probing these various interfaces allows the development of predictive relationships between structure and activity that are determined by nanomaterial properties such as size, shape, surface chemistry, roughness and surface coatings. This knowledge is important from the perspective of safe use of nanomaterials.