Improved Absorption Properties Research Articles

Development of hybrid cotton/hydrogel yarns with improved absorption properties for biomedical applications

Hyperhidrosis, or excessive sweating, is an overlooked and potentially disabling symptom, which is often seen in social anxiety disorder. In this work an innovative advanced textile material was developed for application in the management of excessive sweating, preparing a drying yarn providing improved comfort. Hybrid cotton/hydrogel yarns were obtained by combining cotton with superabsorbent hydrogels through an optimization study focused on the achievement of the most promising product in terms of absorption properties and resistance to washings. Swelling and washing tests were performed using different hydrogels, and the effect of an additional crosslinking on the materials was also evaluated by testing different solutions containing Al3+ and Ca2+ ions. Scanning electron microscopy and infrared spectroscopy analyses were adopted to characterize morphology and chemical structure of the hydrogels undergoing different production processes. The biocompatibility of the hybrid fabrics was demonstrated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide colorimetric assay (MTT) through the extract method.

Testing, simulation and evaluation of a novel hybrid energy absorber

Railway vehicles require energy absorbers which dissipate energy at a constant load, resist transverse loading and which are compact. In addition, accurate numerical models of the crumple zones are also required. A novel expansion-splitting (hybrid) energy absorber is proposed by the authors to provide improved energy absorption properties over existing devices.Dimensionally scaled tubes, incorporating expansion, splitting and expansion-splitting dies, were tested under quasi-static and dynamic conditions. Six different dies, with expansion ratio R = 1.10 and R1.25, die conical semi-angle A = 15° and A = 30° and flaring radii D = 8 mm and D = 12 mm, were used in the experiments to crush the tubes. Calibrated numerical models and parameters found in previous investigations (fracture strain and friction) were included in the numerical models of the expansion-splitting tubes.For the quasi-static testing, the expansion tubes exhibited the greatest force efficiency. The splitting tubes exhibited the greatest stroke efficiency. However, the expansion-splitting tubes exhibited the greatest combined overall efficiency.The numerical simulation accurately predicted the performance of the expansion-splitting tubes under quasi-static conditions. The energy absorption of these tubes was predicted within 2% of the observed test results.

Impact of silica-coating on the microwave absorption properties of carbonyl iron powder

Microwave absorption properties, especially the band width and depth of reflection loss are highlighted as key measurement in studies of microwave absorber. In order to improve the band width and depth of reflection loss of carbonyl iron powder (CIP), we prepared SiO2 layers on the surface of CIP by using tetraethyl orthosilicate (TEOS) as a SiO2 source and 3-aminopropyl triethoxysilane (APTES) as a surface modifier. SiO2 layer was formed by the hydrolysis of TEOS. The results show that after treatment the CIP is covered by a 5–10nm coating layer. Contrast to uncoated samples, coated samples show improved absorption properties. The minimum of reflection loss is −38.8dB at 11GHz and the band width of reflection loss exceeding −10dB is from 8GHz to 14GHz.

Side chain engineering and conjugation enhancement of benzodithiophene and phenanthrenequnioxaline based conjugated polymers for photovoltaic devices

ABSTRACTA series of donor‐acceptor conjugated polymers incorporating benzodithiophene (BDT) as donor unit and phenanthrenequnioxaline as acceptor unit with different side chains have been designed and synthesized. For polymer P1 featuring the BDT unit and alkoxy chains substituted phenanthrenequnioxaline unit in the backbone, serious steric hindrance resulted in quite low molecular weight. The implementation of thiophene ring spacer in polymer P2 greatly suppressed the interannular twisting to extend the effective conjugation length and consequently gave rise to improved absorption property and device performance. In addition, utilizing the alkylthienyl side chains to replace the alkyl side chains at BDT unit in polymer P3 further enhanced the photovoltaic performance due to the increased conjugation length. For polymer P4, translating the alkoxy side chains at the phenanthrenequnioxaline ring into the alkyl side chains at thiophene linker group enhanced molecular planarity and strengthened π−π stacking. Consequently improved absorption property and increased hole mobility were achieved for polymer P4. Our results indicated that side chain engineering not only can influence the solubility of polymer but also can determine the polymer backbone planarity and hence the photovoltaic properties. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1915–1926

Graphene oxide and hyperbranched polymer-toughened hydrogels with improved absorption properties and durability

Hyperbranched polymers or/and graphene oxide nanosheets were used to synthesize poly(acrylic acid)-based hybrid hydrogels with high water absorption ability, excellent mechanical properties, and environmental remediation abilities through a novel one-step, cost-effective, and environmentally friendly method. The combination of hyperbranched polymers and graphene oxide nanosheets had synergistic effects on the final hybrid hydrogel, especially on the mechanical behaviors of the hydrogels, with Young’s modulus, tensile strength at break and elongation at break increasing by 69, 308, and 848 %, respectively, while the other properties remained similar to those of pure poly(acrylic acid). The proposed enhancement mechanism is also discussed.

Planar amine-based dye features the rigidified O-bridged dithiophene π-spacer: A potential high-efficiency sensitizer for dye-sensitized solar cells application

This work reports a systematically theoretical study concerning the design of D–π–A organic dyes for DSSC. Two elaborate strategies, namely the rigidity of dithiophene and introduction of strong electron rich/deficient moieties, are proposed. By using the state-of-the-art theoretical calculations, the general influences of fastening atoms (C, N, and O) for π-spacer rigidification in planar amine-based organic dyes are firstly investigated and elucidated. The properties of isolated dye, dye/(TiO2)38, and dye–I2 interaction are discussed in detail. The results show that, compared with the P2T dye containing dithiophene π-spacer, its three counterparts with rigidified dithiophene π-spacers would present the improved absorption properties. We further demonstrate that incorporation of O-bridged dithiophene moiety into the π-spacer was promising to challenge the photoelectric conversion efficiency 8.29% of P2T. Furthermore, benzothiadiazole (BTD) and 3,4-ethylenedioxythiophene (EDOT) moieties are the well-known π-skeletons that can effectively tune the electronic structure properties and the light-harvesting ability. Subsequently, a series of dyes are designed through introducing the BTD and EDOT groups into π-spacer. The calculated results reveal that the dye with the incorporation of EDOT moiety would be more beneficial for photocurrent and photovoltage performance. The current theoretical studies are expected to be very relevant for the molecular design of D–π–A organic dyes in DSSC.

Preparation and characterization of PVDF-montmorillonite mixed matrix hollow fiber membrane for gas–liquid contacting process

Porous PVDF-hydrophobic montmorillonite (MMT) mixed matrix membranes (MMMs) were fabricated via wet spinning method and used in membrane gas absorption process. The effects of hydrophobic MMT nano-clay loadings (1, 3 and 5wt% of polymer) on the structure and performance were investigated. The fabricated membranes showed both finger-like and sponge-like structure with an increase in the length of finger-like pores in their cross-section, which resulted in higher permeability and lower mass transfer resistance compared to plain PVDF membrane. Also, significant improvements for surface hydrophobicity, critical entry pressure of water and porosity with the addition of filler were observed. The CO2 absorption test was conducted through the gas–liquid membrane contactor and demonstrated a significant improvement in the CO2 flux with MMT loading and the membrane with 5wt% MMT presented highest performance. For example, at the liquid water velocity of 0.5ms−1, CO2 flux of the MMM with 5wt% MMT of 9.73×10−4molm−2s−1 was approximately 56% higher than the PVDF membrane without nano-filler. In conclusion, MMMs with improved absorption properties can be a promising candidate for CO2 absorption and separation processes through membrane contactors.

Synthesis and SEM Analysis of Ketoprofen-Hidroxipropil-β-Cyclodextrin Microparticles for Medical Applications as Drug-Release System with a High Bioavailability

Drug-release systems are studied lately for increasing absorption in the body and improve the therapeutic effectiveness is key objective. Whatever form it may take a drug release system: tablet, implant, injectable suspension or transdermal system, the basic unit on which effective therapeutic drug particle. Knowledge of particle size distribution in a disperse system is of great importance in pharmaceutical technology. The size, surface area and volume-surface particle may be relevant to the physical, chemical and pharmacological drug toxicities. Stability and speed of dissolution of ketoprofen are much reduced in pure and coupled with a solubility promoter, enhances the bioavailability and particle size distribution depends. In order to improve absorption properties of ketoprofen were synthesized drug microparticles containing ketoprofen and hydroxypropyl beta cyclodextrin. Drug microparticles were studied by SEM microscopy and the results correlated with solubility properties. It was found that microparticles obtained are more easily soluble than pure ketoprofen and small size increases bioavailability.

Indoline-based dyes with antenna groups for dye-sensitized solar cells

Indoline-based dyes (In-In and TPD-In dyes) with a homoleptic or a heteroleptic antenna group were designed, and their electronic and optical properties were investigated theoretically to enhance the photovoltaic performance in dye-sensitized solar cells (DSSCs). To gain insight into the factors responsible for photovoltaic efficiencies, we performed density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations for those dyes. The DFT and the TDDFT calculations showed that both the N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TPD) antenna and the indoline electron donor in the TPD-In dye contributed to the transitions in the absorption spectrum, showing that the TPD-In dye had improved absorption property. We found that the effective use of an additional antenna group might take place for an appropriate design in which the highest occupied molecular orbital (HOMO) level for the antenna group is located higher than that for the electron donor. This study suggests that an indoline-based dye sensitizer would show improved photovoltaic performance in the conversion efficiency for DSSCs through the addition of a heteroleptic antenna group.

Comparison Analysis of Absorption Properties for Microwave Absorbent

In order to compare the absorbing properties of different microwave-absorbing agents and their mixture, this paper has selected two typical microwave-absorbing agents which respectively are carbon fiber resistance microwave-absorbing agents and ferrite magnetism microwave-absorbing agents, and took them as monolayer absorbing materials. Then used MG formula to calculate the effective electromagnetic parameter of their mixture under different proportion at X band, and finally analyzed their absorbing properties separately. Then through contrasting the impedance matching characteristic and attenuation coefficient of the materials, it is proved that adding carbon fiber in ferrite can not improve absorption properties. Although the ability of attenuating electromagnetic wave would be enhanced when resistance materials and magnetism materials are blend with each other, doping will destroy the materials’ impedance matching characteristic because most resistance materials have high permittivity. It makes reflection strengthen and can not improve absorbing properties.

Biomimetic Bi2WO6 with hierarchical structures from butterfly wings for visible light absorption

Biomimetic Bi2WO6 with hierarchical structures inherited from butterfly wings (morph-Bi2WO6) were fabricated by a simple soaking and calcinating method. The hierarchical structures down to nanometer level were retained in the resultant morph-Bi2WO6 with pure orthorhombic phase, indicating that our biomimetic approach is effective in controlling the composition and structure of Bi2WO6. The reflectance spectra showed an improved absorption property of morph-Bi2WO6 under visible light over the Bi2WO6 powder synthesized under the same condition without butterfly wings, owing to the hierarchical structures. The strategy is expected to extend to other ternary compound materials for potential applications in water splitting and photocatalyst.

Acid, acrylamide and zeolite modification of cellulosic esparto fibers for dyes decolourisation

The decolourisation of reactive and cationic dyes by physical and chemical modified esparto fibers was investigated. Previously the decolourisation of reactive dyes only had been tested and optimized using untreated esparto fibers and those reinforced by zeolite. Non-treated cellulosic esparto fibers can absorb an important amount of dyes. In order to improve absorption properties of esparto fibers, chemical graft copolymerization with acrylic acid (AA), itaconic acid (IA), and a mixture of acrylamide and IA was performed using potassium persulfate as initiator. The effect of physical modification by zeolite was investigated. Reinforced zeolite esparto fibers were obtained from cellulose esparto fibers pre-treated with NaOH, and preformed zeolite powders. The IR spectroscopy, X-ray diffraction, thermal behavior, as well as the surface morphology of the treated fibers were also studied. The results showed that zeolite treated esparto fibers (the first time application of this kind) are more efficient adsorbents than luffa fibers.

Electromagnetic wave absorption properties of nanocrystalline Fe-based P/M sheets incorporating multi-walled carbon nanotubes

Nanocrystalline soft magnetic Fe73Si16B7Nb3Cu1 (at.%) powders were mixed with fine multi-walled carbon nanotube (MWNT) powders and polyurethane based binders. The mixtures were tape-cast, dried and then cold-rolled to form EM wave absorption sheets. The MWNT powders were added to the Fe-based powders up to 1 wt.% to improve the EM wave absorption properties. The processed sheets with 0.5 mm in thickness were cut into toroidal shape to measure the S-parameter, permeability, permittivity, and power loss at the high frequency of 10 MHz to 10 GHz. As a result, improved absorption properties were obtained from the sheets incorporating MWNT. The results were caused by the increase of dielectric loss of the absorption sheets, which was due to the addition of MWNT powder inducing a notable increase in complex permittivity.

Purifying behavior of photocatalytic TiO 2 anodized in nitrate ion containing solution

Mesoporous titanium dioxide films were fabricated on titanium plates by micro-arc oxidation method. To increase the photocatalytic activity of the films, NH 4NO 3 was added to the H 2SO 4 solution, and anodizing was carried out at high voltages using a DC power supply. The crystal structure, chemical composition, surface morphology and the optical property of the films were investigated by XPS, XRD, UV-VIS spectroscopy and SEM. The photocatalytic activity of the films was evaluated by the decomposition of aniline blue, and the activity of the films for the degradation turned out to be improved by the additives to the electrolyte solution. The enhanced photocatalytic activity might result from the increased porosity and nitrate ion incorporation into the anodic films by micro arcing, and thereby the TiO 2 layer might exhibit an improved absorption property for the visible light.

Experimental studies of sound absorption by church pews

The influence of pews on the acoustical characteristics of churches may be significant because they occupy large areas in rooms lacking absorbing surfaces. However, the information about this particular category of seating is sparse and, sometimes, contradictory. Different types of pews, differing in materials and construction, were analysed in a reverberant chamber by means of Bradley’s method, measuring the absorption coefficients of blocks with different perimeter-to-area ratios. A substantial dependence on the latter parameter was found, allowing prediction of absorption coefficients as a function of actual block dimensions. The presence of upholstered kneelers showed improved absorption properties which were also replicated on other pew types by adding strips of polyester fibre. On-site measurements in three churches were used to validate the method by means of direct application of Sabine’s formula and by means of virtual acoustic modelling. The first only provided satisfactory results in rooms complying with Sabine’s assumptions, while the second also gave good results in the other church with markedly non-uniform absorption. Finally, the application to computer models of absorption coefficients measured in the chamber was discussed.

New Pyrrolopyrimidin‐6‐yl Benzenesulfonamides: Potent A2B Adenosine Receptor Antagonists.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

New pyrrolopyrimidin-6-yl benzenesulfonamides: Potent A 2B adenosine receptor antagonists

A new series of 4-(1,3-dialkyl-2,4-dioxo-2,3,4,5-tetrahydro-1 H-pyrrolo[3,2- d]pyrimidin-6-yl)benzenesulfonamides has been identified as potent A 2B adenosine receptor antagonists. The products have been evaluated for their binding affinities for the human A 2B, A 1 and A 3 adenosine receptors. 6-(4-{[4-(4-Bromobenzyl)piperazin-1-yl]sulfonyl}phenyl)-1,3-dimethyl-1 H-pyrrolo[3,2- d]pyrimidine-2,4(3 H,5 H)-dione ( 16) showed a high affinity for the A 2B adenosine receptor (IC 50 = 1 nM) and selectivity (A 1: 183x; A 3: 12660x). Synthesis and SAR of this novel class of compounds showing improved absorption properties is presented herein.

Construction of a Functional Transporter Analysis System Using MDR1 Knockdown Caco-2 Cells

The efflux transporter, P-glycoprotein (P-gp), located in the brush-border membrane of intestinal absorptive cells, reduces the bioavailability of a wide range of orally administered drugs. Using P-gp inhibitors in transport experiments in Caco-2 cell monolayers is widely accepted as an efficient way to estimate the contribution of P-gp to the intestinal absorption of drugs. However, there still remain some arguments that the inhibitors might affect the function of other proteins. Multidrug resistance 1 gene (MDR1) specifically inhibited Caco-2 cells were constructed, therefore, as a better in vitro evaluation system of intestinal drug absorption. The effective sites of RNAi were selected using siRNA libraries and single siRNAs and MDR1 stable knockdown Caco-2 cells were constructed using a tRNA(val)-shRNA expression vector. In siRNA stably expressed Caco-2 cells, the expression level of MDR1 was reduced at mRNA and protein levels. Transcellular transport studies using digoxin revealed that the P-gp function was suppressed completely, similar to that in verapamil-treated cells. MDR1 stable knockdown Caco-2 cells were successfully constructed by RNAi technology. This will consequently allow the development of a selection system for candidate drugs with improved absorption properties.

Novel gastroretentive dosage forms: evaluation of gastroretentivity and its effect on riboflavin absorption in dogs.

[corrected] The purpose of this study was to design novel gastroretentive dosage forms (GRDFs) based on unfolding multilayer polymeric films, to investigate the mechanism of their gastroretentivity in dogs, and to assess the effect of compounding a narrow absorption window drug in a GRDF on the drug's absorption properties. Dosage forms (DFs) with different dimensions and mechanical properties were administered to beagle dogs with acidic buffer (pH = 1.5), whose gastric retention time (GRT) was then determined by X-ray pictures. Concurrent administration of radiopaque markers was used to assess the effect of the GRDF and/or acidic buffer on GRT. The absorption of riboflavin from a prototype GRDF was compared with a nongastroretentive controlled-release DF and to an oral solution of the drug. Large DFs (> or = 2.5 x 2.5 cm) containing rigid frame had prolonged GRT (>4 h). Administration of 400 mL of acidic buffer (or water) prolonged GRT whereas the GRDF did not cause additional prolongation. The extended absorption phase (>48 h) of riboflavin administered in a GRDF led to 4-fold increased bioavailability. The combination of large dimensions with rigidity produce gastroretentivity that can be used to improve absorption properties of a model of narrow absorption window drugs in the gastrointestinal tract.

Improvement of buccal delivery of morphine using the prodrug approach

The feasibility of achieving buccal delivery of morphine using the prodrug approach was assessed by studies of bioactivation, in vitro permeation and in vivo absorption. The bioactivation of various morphine-3-esters was studied in human plasma and saliva. The in vitro permeation of morphine and various morphine-3-esters was studied using porcine buccal mucosa mounted in Ussing chambers and finally the in vivo absorption of the compounds evaluated following administration in rats. Both the results from the in vitro permeation and from the absorption of the prodrugs studied suggested a parabolic relationship to the lipophilicity of the compounds. In the in vitro studies the optimal permeation was achieved for the prodrug morphine-3-propionate having a log P value of approximately 0.7. In contrast to that optimal in vivo absorption was obtained for the prodrug morphine-3-acetate having a log P value of 0.2. This discrepancy could however be explained by the enzymatic stability of the two esters in saliva, since it was found that morphine-3-propionate was more rapidly hydrolysed in saliva than was morphine-3-acetate. The study demonstrates that the buccal delivery of morphine can be markedly improved by using ester prodrugs with higher lipophilicity than morphine itself. However, the enzymatic stability of the prodrugs in saliva also play an important role for the overall improvement in absorption properties.