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Search Results: 1 - 10 of 18396 matches for " polymer B "
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Preparation and evaluation of transdermal drug delivery system of etoricoxib using modified chitosan
Wahid A,Sridhar B,Shivakumar S
Indian Journal of Pharmaceutical Sciences , 2008,
Abstract: In the present investigation chitosan has been chemically modified by treating with two different aldehydes like acetaldehyde and propionaldehyde to form Schiff′s bases. Schiff′s bases of chitosan with acetaldehyde and propionaldehyde were named as polymer A and polymer B, respectively. Fourier Transform Infra Red (FTIR) spectral data have confirmed the reaction carried out on chitosan. Drug free polymeric films of chitosan, chemically modified chitosan and chitosan/hydroxypropylmethylcellulose blend were prepared and evaluated for various physicochemical characters. Further, the films were incorporated with anti-inflammatory drug, etoricoxib using glycerol as plasticizer. The drug loaded films were cross-linked with sodium citrate and studied for permeation characteristics across dialysis membrane and rat skin. All the films were evaluated for bursting strength, swelling index, moisture uptake, thickness uniformity, drug content uniformity, tensile strength, percent elongation at break, percent flatness, water vapour transmission rate and in vitro drug permeation study.
Microscopic Characterization of Ecological Concrete Polymeric  [PDF]
A. D. Rodríguez, M. L. Domínguez, R. M. Melgoza
Microscopy Research (MR) , 2014, DOI: 10.4236/mr.2014.21003
Abstract:

The Scanning Electron Microscopy (SEM) and Optical Microscopy (OM) with integrated digital camera are techniques that are used in the present investigation, for the morphological characterization of a new composite material called “organic polymer concrete” in which microparticles added fibers and polyethylene terephthalate (PET) recycling mechanically (RM). Polymer concrete (PC) is a new composite material (MC) in the application considered as an alternative material of construction in which reinforcement particles are recycled polymers which have approximately the same dimensions in all directions. Therefore, the particles can be rods, spheres, chips and many other shapes whose appearance reasons are about 10 microns. These MC, the size, shape and distribution and the ratio and the modulus of the particles affect the properties of the material.

Use of a glucomannan polymer to reduce the effects of mycotoxin-contaminated diets in finishing pigs
G. Battacone,G. A. Carboni,P. Nicolussi,C. Ligios
Italian Journal of Animal Science , 2010, DOI: 10.4081/ijas.2007.1s.673
Abstract: The use of feed additives with mycotoxin adsorption capacity is a common strategy for controlling negative effects of mycotoxins in swine production systems. However, adsorbents that may results very effective under experimental conditions, i.e. when feed contamination level is rather high, do not necessarily retain their efficacy when tested under field conditions feed with generally low mycotoxin contamination. In this study, the effects of diets artificially contaminated with aflatoxin B1 or ochratoxin A on fattening performance and serum chemistry of fattening pigs are investigated. Moreover, the ability of a commercial glucomannan polymer (Gm polimer) to reduce or eliminate the effects of the contaminated feeds is tested. Thirty heavy pigs (BW = 110±10.6 kg) were fed 6 diets (n = 5 pigs/diet) for 4 weeks until slaughtering. Diets were: control without toxin added (C); added with 0.02 ppm of aflatoxin B1 (AFB1); added with 0.05 ppm of ochratoxin A (OTA); other three diets as the previous but the addition of 2.0 g/kg of Gm polymer (C-GM, AFB1-GM, OTA-GM). Daily weight gain (ADG) and Feed efficiency ratio (FE) were measured every two weeks. Data were analyzed with a two-way ANOVA that included the fixed effect of diet, time and their interaction. After the first 2 weeks the ADG did not differ significantly between the diets, even if the ADG of AFB1 diet was about 20% lower than AFB1-Gm or C. In the last 2 weeks the ADG of AFB1 diet was significantly lover than the other diets (P<0.01) and was about one-half of the values reported for the same group in the first period. The contamination with ochratoxin A did not affect fattening performance of pigs during the whole experimental period. No damages were found in kidneys of all diets. Moreover, no evidence of association between observed liver damages and different diets was found. Finally, no differences between experimental diets were evidenced for the haematological parameters.
On the adsorbed mass of polymers on surfaces (NOTE)
GEORGIOS K. STRATOURAS
Journal of the Serbian Chemical Society , 2001,
Abstract: It is shown that for ideal polymers interacting with a surface via the pseudopotential of a delta function, the number of contacts between the monomer units and the surface as a function of concentration cb is a dependence of the form acb/(1 bcb). The architecture of the polymer, the degree of polymerization, the interaction energy between a monomer unit and the surface, the area of the surface and the monomer length are embodied in the parameters a and b. The above dependence of the adsorbed mass of a polymer on the concentration is confirmed by the experimental results of Takahashi and his collaborators. For linear polystyrene of molecular weight 134×105,interacting with a chrome plate, the parameters a and b are, respectively, about equal to (89938/273) ×10-6 m and ( 19300/273) m3 kg-1.
Photocatalytic Degradation of Rhodamine B Using Semiconductors Photosensitized by Poly(fluorene-co-thiophene) under Visible Light Irradiation
芴与噻吩共聚物敏化半导体在可见光下催化降解罗丹明B

ZHANG Dong-dong,MO Yue-qi,SONG Lin,HUANG Xiong-fei,QIU Rong-liang,
张冬冬
,莫越奇,宋琳,黄雄飞,仇荣亮

过程工程学报 , 2008,
Abstract: 可见光照射下,芴与噻吩共聚物(PFT)敏化TiO2和ZnO具有优良的催化性能,降解罗丹明B的实验表明,PFT/TiO2的催化活性明显高于PFT/ZnO.经过2 hLED(Light-emittingDiode)灯照射,PFT/TiO2体系中,罗丹明B完全降解为无色物质,矿化率48%;而PFT/ZnO体系中,同样条件下,2 h后还存在大量有色的罗丹明B降解中间产物,矿化率只有24.6%.罗丹明B的降解过程分两个阶段,第一阶段最大吸收峰降低的同时,发生光谱蓝移,最终脱色生成罗丹明,第二阶段罗丹明继续降解为CO2和H2O,TOC的去除主要发生在第二阶段.
Polymer-Optical-Fiber Lasers and Amplifiers Doped with Organic Dyes
Jon Arrue,Felipe Jiménez,Igor Ayesta,M. Asunción Illarramendi,Joseba Zubia
Polymers , 2011, DOI: 10.3390/polym3031162
Abstract: Polymer optical fibers (POFs) doped with organic dyes can be used to make efficient lasers and amplifiers due to the high gains achievable in short distances. This paper analyzes the peculiarities of light amplification in POFs through some experimental data and a computational model capable of carrying out both power and spectral analyses. We investigate the emission spectral shifts and widths and on the optimum signal wavelength and pump power as functions of the fiber length, the fiber numerical aperture and the radial distribution of the dopant. Analyses for both step-index and graded-index POFs have been done.
ESTADO DE PORTADORES DE BORDETELLA PERTUSSIS EN ADOLESCENTES DE 12 A 19 A?OS EN EL DEPARTAMENTO DEL TOLIMA, COLOMBIA, 2007
Morón Duarte,Lina Sofía; Moreno,Jaime; Gracia,Martha; Realpe,María Elena; Pe?a Daza,Gilma Lucia;
Investigaciones Andina , 2008,
Abstract: antecedents: studies have revealed that bordetella pertussis is present in a significant number of adolescents and adults, thus confirming its agency in the development of the syndrome in up to 30% of the cases examined. this may in turn play an important role in the transmission of the disease to breast fed children. to determine the nature of the bacteria b. pertussis in adolescents carriers, residents of tolima and to evaluate the efficacy of the polymerase (pcr) chain reaction strategy as a diagnostic medium on the carrier. methods: a field study conducted on a cross section of the population in which 400 youths between the ages of 12 and 19 were selected by means of random testing. nasopharyngeal samples were collected and treated with live cultive techniques: direct immunofluorescence (ifd) with polyclonal antibodies on the one hand, and polymerase (pcr) is4801-is4802 chain reaction methods on the other. treatment was undertaken in the national institute for health. results: 400 samples were treated with negative cultures: 34 (8.5%) tested positive with ifd and 132(33%) with pcr. both techniques were positive 29(17%) and 263(66%) negative with ifd and pcr. of the total samples taken 34.25% (137/400) were positive. the sensitivity of pcr in relation to ifd was 85.3% (ic:95%, 15,4- 30.2) and in relation to vpn was 98.1% (ic:95%, 95.5-99.3). conclusions: carriers of the strain tested with ifd and pcr are shown to be healthy, nevertheless the live bacteria remains the prototype of the illness and for this reason the study is inconclusive in its findings. a process of continual assessment into the condition of the b.pertussis carriers is necessary in order to ascertain whether, amongst those diagnosed by live cultures, there are not those who are asymptomatic carriers.
A STUDY INTO THE CARRIERS OF BORDETELLA PERTUSSIS BETWEEN 12 AND 19 YEARS OLD TOLIMA, COLOMBIA 2007
MORON-DUARTE Lina Sofía,MORENO Jaime,Gracia Martha,Realpe Maria Elena
Investigaciones Andina , 2008,
Abstract: Antecedents: studies have revealed that Bordetella Pertussis is present in a significant number of adolescents and adults, thus confirming its agency in the development of the syndrome in up to 30% of the cases examined. This may in turn play an important role in the transmission of the disease to breast fed children. To determine the nature of the bacteria B. Pertussis in adolescents carriers, residents of Tolima and to evaluate the efficacy of the polymerase (PCR) chain reaction strategy as a diagnostic medium on the carrier. Methods: a field study conducted on a cross section of the population in which 400 youths between the ages of 12 and 19 were selected by means of random testing. Nasopharyngeal samples were collected and treated with live cultive techniques: direct immunofluorescence (IFD) with polyclonal antibodies on the one hand, and polymerase (PCR) IS4801-IS4802 chain reaction methods on the other. Treatment was undertaken in the National Institute for Health. Results: 400 samples were treated with negative cultures: 34 (8.5%) tested positive with IFD and 132(33%) with PCR. Both techniques were positive 29(17%) and 263(66%) negative with IFD and PCR. Of the total samples taken 34.25% (137/400) were positive. The sensitivity of PCR in relation to IFD was 85.3% (IC:95%, 15,4- 30.2) and in relation to VPN was 98.1% (IC:95%, 95.5-99.3). Conclusions: carriers of the strain tested with IFD and PCR are shown to be healthy, nevertheless the live bacteria remains the prototype of the illness and for this reason the study is inconclusive in its findings. A process of continual assessment into the condition of the B.Pertussis carriers is necessary in order to ascertain whether, amongst those diagnosed by live cultures, there are not those who are asymptomatic carriers.
Electronic structures and spectra of conducting anthracene derivatives
ZHONGFA WANG,SHI WU
Journal of the Serbian Chemical Society , 2008,
Abstract: Theoretical studies on anthracene and a series of its derivatives were performed using the AM1 method and DFT. Based on B3LYP/6-31G(d) optimized geometries, the electronic, IR and NMR spectra of anthracene oligomers were calculated using the Indo/Cis, AM1 and B3LYP/6-31G(d) methods, respectively. The energy gaps of the oligomers decreased and the main absorptions in the electronic spectra of the oligomers were red-shifted, whereas the IR frequencies for some of the C=C and C–H bonds were blue-shifted with increasing chain length and in the presence of substituents. The 13C-NMR chemical shifts of the bridged carbon atoms were upfield shifted in the presence of an electron-donating group, while the chemical shifts of the carbon atoms on the two side rings of the anthracene moiety shifted downfield in the presence of an electron-withdrawing group.
Rheological Properties of Polymers: Structure and Morphology of Molten Polymer Blends  [PDF]
Oluranti Sadiku-Agboola, Emmauel Rotimi Sadiku, Adesola Taoreed Adegbola, Olusesan Frank Biotidara
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.21005
Abstract: The article reviews a brief literature on the rheological properties of polymer melts and blends. Experimental results on polymer blends are summarized. Technically, vital types of multi-phase polymers such as compounds and blends are discussed. The importance of the rheological properties of polymer mixtures in the development of the phase structure is discussed. And the importance of considering the stress and/or strain history of a material sample in a rheological investigation is discussed. Finally, the outlook on the past, present and future developments in the field of polymer rheology are given. The review concludes with a brief discussion on the opportunities and challenges in the field of polymer blends and blend rheology.
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