Dielectric relaxation of monoesters based poly(styrene-co-maleic anhydride) copolymer

A series of alkyl-grafted copolymers based on styrene-maleic anhydride (SMA) copolymers were synthesized by esterification of SMA with several long chain normal aliphatic alcohols. The prepared copolymers were characterized by FT-IR and ¹H NMR and DSC. The dielectric behavior of these copolymers was investigated in the frequency 20–10⁵ Hz and temperature −40 to 180 °C ranges. Two relaxation processes were observed, α, and β-relaxation. The former is associated with the glass-rubber transition and is characterized by the Vogel–Fulcher–Tammann temperature dependence and the latter relaxation is related to the local motion of the ester side groups attached to the polymer backbone. The apparent activation energy for the β-relaxation was found to depend significantly on the alkyl chain length. The dielectric analysis of the β-relaxation process detected is discussed.     

Ozonation of oil sands process-affected water accelerates microbial bioremediation

Ozonation can degrade toxic naphthenic acids (NAs) in oil sands process-affected water (OSPW), but even after extensive treatment a residual NA fraction remains. Here we hypothesized that mild ozonation would selectively oxidize the most biopersistent NA fraction, thereby accelerating subsequent NA biodegradation and toxicity removal by indigenous microbes. OSPW was ozonated to achieve approximately 50% and 75% NA degradation, and the major ozonation byproducts included oxidized NAs (i.e., hydroxy- or keto-NAs). However, oxidized NAs are already present in untreated OSPW and were shown to be formed during the microbial biodegradation of NAs. Ozonation alone did not affect OSPW toxicity, based on Microtox; however, there was a significant acceleration of toxicity removal in ozonated OSPW following inoculation with native microbes. Furthermore, all residual NAs biodegraded significantly faster in ozonated OSPW. The opposite trend was found for ozonated commercial NAs, which are known to contain no significant biopersistent fraction. Thus, we suggest that ozonation preferentially degraded the most biopersistent OSPW NA fraction, and that ozonation is complementary to the biodegradation capacity of microbial populations in OSPW. The toxicity of ozonated OSPW to higher organisms needs to be assessed, but there is promise that this technique could be applied to accelerate the bioremediation of large volumes of OSPW in Northern Alberta, Canada.     

On the Optimality of the ARQ-DDF Protocol

In this correspondence, the performance of the automatic repeat request-dynamic decode and forward (ARQ-DDF) cooperation protocol is analyzed in two distinct scenarios. The first scenario is the multiple access relay channel where a single relay is dedicated to simultaneously help two multiple access users. For this setup, it is shown that the ARQ-DDF protocol achieves the channel's optimal diversity multiplexing tradeoff (DMT). The second scenario is the cooperative vector multiple access channel where two users cooperate in delivering their messages to a destination equipped with two receiving antennas. For this setup, a new variant of the ARQ-DDF protocol is developed where the two users are purposefully instructed not to cooperate in the first round of transmission. Lower and upper bounds on the achievable DMT are then derived. These bounds are shown to converge to the optimal tradeoff as the number of transmission rounds increases.     

Diglycidyl ether of bisphenol A/chitosan‐graft‐polyaniline composites with electromagnetic interference shielding properties: Synthesis,characterization, and curing kinetics

Conducting filler based on chitosan and grafted polyaniline (Ch‐g‐PANI) was prepared with different grafting ratios and used as fillers for polyester powder coating system. Differential scanning calorimetry is applied to study the effect of Ch‐g‐PANI on the curing of the polyester powder coating. The activation energy calculated by isoconversional Kissinger method was increased by either increasing the Ch‐g‐PANI content or the content of polyaniline in the filler, suggesting the contribution of the filler in the curing reactions. The cured samples were characterized using FTIR and TG analyses. Thermogravimetric analysis showed that the total thermal stability was enhanced upon the filler addition as detected from the values of integral procedural decomposition temperature. Furthermore, a dielectric study showed that the dielectric constant and loss were increased upon increasing of the filler. Vogel–Fulcher–Tammann equation was well‐fitted when used to examine the dependence of α‐relaxation on the temperature and the dielectrically calculated T_g values were comparable to that measured by DSC. The shielding effectiveness toward microwaves was enhanced by increasing the filler content. POLYM. ENG. SCI., 59:372–381, 2019. © 2018 Society of Plastics Engineers     

Arabic sign language intelligent translator

ABSTRACT

Arabic sign language (ArSL) is method of communication between deaf communities in Arab countries; therefore, the development of systemsthat can recognize the gestures provides a means for the Deaf to easily integrate into society. In this research we implemented a computational structurefor an intelligent interpreter that automatically recognizes the isolated dynamic gestures. The proposed system recognizes and translates gesturesperformed with one or both hands. It comprises five subsystems, building dataset, video processing, feature extraction, mapping between ArSL and Arabictext, and text generation. To apply the system, 100-signs of ArSL was used, which was applied on 1500 video files. It's were divided into five classes:alphabet, numbers, "prepositions, pronouns and question words", Arabic life expressions, and "nouns and verbs". The evaluation indicated that thesystem automatically recognizes and translates isolated dynamic ArSL gestures by highly accurate manner. The results showed that the system accuracy is 95.8%.     

Controlled precipitation for enhanced dissolution rate of flurbiprofen: development of rapidly disintegrating tablets

Objective: The aim of this work was to investigate the potential of controlled precipitation of flurbiprofen on solid surface, in the presence or absence of hydrophilic polymers, as a tool for enhanced dissolution rate of the drug. The work was extended to develop rapidly disintegrated tablets.

Significance: This strategy provides simple technique for dissolution enhancement of slowly dissolving drugs with high scaling up potential.

Methods: Aerosil was dispersed in ethanolic solution of flurbiprofen in the presence and absence of hydrophilic polymers. Acidified water was added as antisolvent to produce controlled precipitation. The resultant particles were centrifuged and dried at ambient temperature before monitoring the dissolution pattern. The particles were also subjected to FTIR spectroscopic, X-ray diffraction and thermal analyses.

Results: The FTIR spectroscopy excluded any interaction between flurbiprofen and excipients. The thermal analysis reflected possible change in the crystalline structure and or crystal size of the drug after controlled precipitation in the presence of hydrophilic polymers. This was further confirmed by X-ray diffraction. The modulation in the crystalline structure and size was associated with a significant enhancement in the dissolution rate of flurbiprofen. Optimum formulations were successfully formulated as rapidly disintegrating tablet with subsequent fast dissolution.

Conclusions: Precipitation on a large solid surface area is a promising strategy for enhanced dissolution rate with the presence of hydrophilic polymers during precipitation process improving the efficiency.     

Development of novel amisulpride-loaded solid self-nanoemulsifying tablets: preparation and pharmacokinetic evaluation in rabbits

Objective: The current investigation is focused on the formulation and in vivo evaluation of optimized solid self-nanoemulsifying drug delivery systems (S-SNEDDS) of amisulpride (AMS) for improving its oral dissolution and bioavailability.

Methods: Liquid SNEDDS (L-SNEDDS) composed of Capryol? 90 (oil), Cremophor^® RH40 (surfactant), and Transcutol^® HP (co-surfactant) were transformed to solid systems via physical adsorption onto magnesium aluminometasilicate (Neusilin US2). Micromeretic studies and solid-state characterization of formulated S-SNEDDS were carried out, followed by tableting, tablet evaluation, and pharmacokinetic studies in rabbits.

Results: Micromeretic properties and solid-state characterization proved satisfactory flow properties with AMS present in a completely amorphous state. Formulated self-nanoemulsifying tablets revealed significant improvement in AMS dissolution compared with either directly compressed or commercial AMS tablets. In vivo pharmacokinetic study in rabbits emphasized significant improvements in t_max, AUC_(0–12), and AUC_(0–∞) at p?<?.05 with 1.26-folds improvement in relative bioavailability from the optimized self-nanoemulsifying tablets compared with the commercial product.

Conclusions: S-SNEDDS can be a very useful approach for providing patient acceptable dosage forms with improved oral dissolution and biovailability.     

Synthesis and characterization of biodegradable poly(ester‐urethanes) based on bacterial poly(R‐3‐hydroxybutyrate)

A series of poly(R‐3‐hydroxybutyrate)/poly(ε‐caprolactone)/1,6‐hexamethylene diisocyanate‐segmented poly(ester‐urethanes), having different compositions and different block lengths, were synthesized by one‐step solution polymerization. The molecular weight of poly(R‐3‐hydroxybutyrate)‐diol, PHB‐diol, hard segments was in the range of 2100–4400 and poly(ε‐caprolactone)‐diol, PCL‐diol, soft segments in the range of 1080–5800. The materials obtained were investigated by using differential scanning calorimetry, wide angle X‐ray diffraction and mechanical measurements. All poly(ester‐urethanes) investigated were semicrystalline with T_m varying within 126–148°C. DSC results showed that T_g are shifted to higher temperature with increasing content of PHB hard segments and decreasing molecular weight of PCL soft segments. This indicates partial compatibility of the two phases. In poly(ester‐urethanes) made from PCL soft segments of molecular weight (M_n ≥ 2200), a PCL crystalline phase, in addition to the PHB crystalline phase, was observed. As for the mechanical tensile properties of poly(ester‐urethane) cast films, it was found that the ultimate strength and the elongation at the breakpoint decrease with increasing PHB hard segment content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 703–718, 2002     

Nitro-Deficient Niclosamide Confers Reduced Genotoxicity and Retains Mitochondrial Uncoupling Activity for Cancer Therapy

Niclosamide is an oral anthelmintic drug, approved for use against tapeworm infections. Recent studies suggest however that niclosamide may have broader clinical applications in cancers, spurring increased interest in the functions and mechanisms of niclosamide. Previously, we reported that niclosamide targets a metabolic vulnerability in p53-deficient tumours, providing a basis for patient stratification and personalised treatment strategies. In the present study, we functionally characterised the contribution of the aniline 4′-NO₂ group on niclosamide to its cellular activities. We demonstrated that niclosamide induces genome-wide DNA damage that is mechanistically uncoupled from its antitumour effects mediated through mitochondrial uncoupling. Elimination of the nitro group in ND-Nic analogue significantly reduced γH2AX signals and DNA breaks while preserving its antitumour mechanism mediated through a calcium signalling pathway and arachidonic acid metabolism. Lipidomics profiling further revealed that ND-Nic-treated cells retained a metabolite profile characteristic of niclosamide-treated cells. Notably, quantitative scoring of drug sensitivity suggests that elimination of its nitro group enhanced the target selectivity of niclosamide against p53 deficiency. Importantly, the results also raise concern that niclosamide may impose a pleiotropic genotoxic effect, which limits its clinical efficacy and warrants further investigation into alternative drug analogues that may ameliorate any potential unwanted side effects.     

Effect of Substituents on Dielectric β-Relaxation in Cellulose

The dielectric characteristics for some cellulose derivatives, namely chlorodeoxycellulose (Cell-Cl; degree of substitution of chlorine, DS_Cl=0·87), bromodeoxycellulose (Cell-Br; DS_Br=0·92) and thiocyanatodeoxycellulose (Cell-SCN; DS_SCN=0·88), all substituted only at C-6, together with those of regenerated cellulose, have been investigated in the temperature range -60 to 120°C, and in the frequency range 0·2–100kHz. Only one relaxation process, designated as β, was identified within the frequency and temperature ranges studied. The activation energy of this relaxation increases in the order Cell-Cl<Cell-Br<Cell-SCN, suggesting that the bulkiness of the substituent was the determining factor of the activation energy. The characteristic dielectric parameters, namely polarization magnitude (Δε) and shape parameter (α or β-), were obtained by the analysis of absorption bands and are discussed in relation to the substituent effect. © of SCI.