Dielectric Analysis of Blended Polysulfone/Polyethylenimine Membrane Contactors for CO2 Capture.

Polysulfone membranes, used as contactors for CO2 capture, are blended with two different hyperbranched polyethyleneimines modified with benzoyl chloride (Additive 1) and phenyl isocyanate (Additive 2) in different percentages. Fourier-transformed infrared spectra evidence the presence of urea and amide groups, whereas the field emission scanning electron microscopy images show differences in the microstructure of the blended membranes. Dielectric spectra determine the motions of the side and backbone chains, which can facilitate the diffusion of CO2 . The spectra consist of six dielectric processes; three of them are due to the polysulfone (γPSf , ßPSf , and αPSf ), whereas the rest are characteristic of the additive (γHPEI , ßHPEI , and αHPEI ). The benzoyl chloride and phenyl isocyanate functional groups introduce variations in molecular mobility and modify the relaxations associated with the hyperbranched polyethyleneimine (HPEI). The additives also increase the conductivity of the blended membranes, which can compromise the performance of the membranes, specifically in the case of Additive 1. Ion hopping is found to be the prevailing charge transport mechanism while both relaxations, αHPEI and αPSf , are actives. These results, together with the final morphology of the membranes, may explain the greater absorption capacity of the membranes prepared with the hyperbranched polyethyleneimine modified with Additive 2.

Chitosan-based emulgel and xerogel film containing Thymus pubescens essential oil as a potential wound dressing.

Controlling the wound exudates accompanied by microbial wound infections has still remained as one the most challenging clinical issues. Herein, a chitosan/gelatin/polyvinyl alcohol xerogel film containing Thymus pubescens essential oil is fabricated for antimicrobial wound dressing application. The chemical and physical characteristics of the devised formulation is characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscope, and tensile tests. Moreover, swelling capability, water vapour transmission rate, water contact angle, solubility, moisture content, and release properties are also studied. The antimicrobial and antibiofilm tests are performed using the broth microdilution and XTT assay, respectively. The produced formulation shows excellent antimicrobial efficacy against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida species. It is also demonstrated that the obtained film can reduce (∼80 %) Candida albicans biofilm formation, and its biocompatibility is confirmed with MTT (∼100 %) and hemolysis tests. The antimicrobial activity can be correlated to the microbial membrane attraction for Candida albicans cells, illustrated by flow cytometry. This proposed film with appropriate mechanical strength, high swelling capacity in different pH values (∼200-700 %), controlled release property, and antimicrobial and antioxidant activities as well as biocompatibility can be used as a promising candidate for antimicrobial wound dressing applications.

Encapsulation of Zataria multiflora essential oil in polyvinyl alcohol/chitosan/gelatin thermo-responsive hydrogel: Synthesis, physico-chemical properties, and biological investigations.

Zataria multiflora essential oil is a natural volatile plant product whose therapeutic applications require a delivery platform. Biomaterial-based hydrogels have been extensively used in biomedical applications, and they are promising platforms to encapsulate essential oils. Among different hydrogels, intelligent hydrogels have recently attracted many interests because of their response to environmental stimuli such as temperature. Herein, Zataria multiflora essential oil is encapsulated in a polyvinyl alcohol/chitosan/gelatin hydrogel as a positive thermo-responsive and antifungal platform. According to the optical microscopic image, the encapsulated spherical essential oil droplets reveal a mean size of 1.10 ± 0.64 µm, which are in consistent with the SEM imaging results. Encapsulation efficacy and loading capacity are 98.66 % and 12.98 %, respectively. These results confirm the successful efficient encapsulation of the Zataria multiflora essential oil within the hydrogel. The chemical compositions of the Zataria multiflora essential oil and the fabricated hydrogel are analyzed by gas chromatography-mass spectroscopy (GC-MS) and Fourier transform infrared (FTIR) techniques. It is found that thymol (44.30 %) and γ-terpinene (22.62 %) are the main constituents of the Zataria multiflora essential oil. The produced hydrogel inhibits the metabolic activity of Candida albicans biofilms (∼60-80 %), which can be related to the antifungal activity of the essential oil constituents and chitosan. Based on the rheological results, the produced thermo-responsive hydrogel shows a gel-sol viscoelastic transition at a temperature of 24.5 °C. This transition leads to a facile release of the loaded essential oil. The release test depicts that about 30 % of Zataria multiflora essential oil is released during the first 16 min. In addition, 2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay demonstrates that the designed thermo-sensitive formulation is biocompatible with high cell viability (over 96 %). The fabricated hydrogel can be deemed as a potential intelligent drug delivery platform for controlling cutaneous candidiasis due to antifungal effectiveness and less toxicity, which can be a promising alternative to traditional drug delivery systems.

The Predictor Roles of Spiritual Well-Being, Healthcare Professionals' Support and Shock Anxiety in Implantable Cardioverter-Defibrillator Device Acceptance.

Background: Acceptance of the implantable cardioverter-defibrillator (ICD) device may be affected by a variety of factors. This study aimed to investigate the predictor roles of spiritual well-being, healthcare professionals' support and shock anxiety in accepting ICD. Methods: This cross-sectional study was conducted on 100 patients with ICD. The data were collected by the Florida Patient Acceptance Scale, Florida Shock Anxiety Scale, Spiritual Well-Being Scale and Healthcare Professionals' Support Questionnaire. Results: The mean (SD) scores of patient acceptance, shock anxiety, spiritual well-being and healthcare professionals' support were 65.4 (13.56), 21.93 (8.95), 88.92 (11.78) and 76.41 (10.54), respectively. The results revealed higher acceptance among the participants with lower shock anxiety levels (r = -0.51, P < 0.001), higher mean scores of spiritual well-being (r = 0.33, P = 0.001) and higher healthcare professionals' support (r = 0.40, P < 0.01). Additionally, the results of linear regression indicated that spiritual well-being, healthcare professionals' support and shock anxiety predicted 36% of the patient acceptance variance (R = 0.61, R 2 = 0.38, adj R 2 = 0.36) and shock anxiety and healthcare professionals' support were the predictors of patient acceptance. Conclusion: The study results indicated that the patients' mean score of acceptance was relatively high. In addition, the mean scores of shock anxiety, spiritual well-being and healthcare professionals' support were low, moderate and relatively high, respectively. Conducting healthcare professionals' support interventions, spiritual therapy and reducing shock anxiety can help patients accept ICDs.

Application of a dual functional blocking layer for improvement of the responsivity in a self-powered UV photodetector based on TiO2 nanotubes.

A layer of graphene quantum dots (GQDs) was applied on the photoanode of a self-powered photoelectrochemical (PEC) UV photodetector based on TiO2 nanotubes (NTs). The GQDs layer acted as a dual functional layer and improved the photodetector performance by both UV light absorption and blocking the charge carriers recombination at the photoanode/electrolyte interface. The short circuit current density (Jsc) and thereby the responsivity of the PEC UV photodetector was enhanced by 473%. The highest value of the responsivity in this work obtained for the PEC UV photodetector with the dual functional GQDs layer was as much as 42.5 mA W-1. This value is far better than previously reported responsivities of the PEC devices based on TiO2 NTs as a photoanode. This high responsivity was obtained under the illumination of a very low intensity UV light (365 nm, 2 mW cm-2) and 0 V bias. Moreover, the sensitivity of the PEC UV photodetector with the dual functional GQDs layer has been improved by 345%, which is almost 3.5 times higher compared to the sensitivity of its counterpart without the GQDs coating. The devices with the dual functional GQDs layer present a splendid repeatability and stability. The rise time and the decay time of this device were measured to be 0.73 s and 0.88 s under the on/off switching UV LEDs, respectively. The electrochemical impedance spectroscopy (EIS) results prove the role of the GQDs layer as an effective blocking layer on the photoanode, hindering the charge carrier recombination at the photoanode/electrolyte interface. This study shows that application of the dual functional GQDs layer in the PEC UV photodetector based on TiO2 NTs is an effective approach for improving the responsivity and sensitivity of a self-powered PEC UV PD, which brought us the possibility of detecting low UV index radiation and using the self-powered photodetectors in cutting-edge wearable electronic devices for the aim of health, safety and environmental monitoring.

Dielectric Properties in Oriented and Unoriented Membranes Based on Poly(Epichlorohydrin-co-Ethylene Oxide) Copolymers: Part III.

The dielectric spectra and conductivity properties of neat poly(epichlorohydrin-co-ethylene oxide)(PECH-co-EO) copolymer and two modified copolymers with a 20% or 40% of dendron 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy] benzoate units were analysed. A process of thermal orientation was applied to the copolymers to fine-tune the molecular motion of the side chains and determine their validity for cation transport materials. The study was conducted using Dielectric Thermal Analysis (DETA). The spectra of the modified unoriented and oriented copolymers consisted of five dielectric relaxations (δ, γ, ß, αTg, and αmelting). The analysis of the relaxations processes shows that as the grafting with the dendron units increases, both the lateral and main chains have a greater difficulty moving. The thermal orientation induces in the main chain partial crystallization, including the polyether segments, and modifies the cooperative motion of the main chain associated with the glass transition (αTg). A deep analysis of the electrical loss modulus revealed that the degree of modification only modifies the temperature peak of each relaxation, and this effect is more perceived if the dendron unit content is higher (40%). The thermal orientation process seems equal to the spectra of CP20-O and CP40-O to the point that the degree of modification does not matter. Nevertheless, the fragility index denotes the differences in the molecular motion between both copolymers (40% and 20%) due to the thermal orientation. The study of the electric conductivity showed that the ideal long-range pathways were being altered by neither the thermal orientation process nor the addition of dendrimers. The analysis of the through-plane proton conductivity confirmed that the oriented copolymer with the highest concentration of dendrimers was the best performer and the most suitable copolymer for proton transport materials.

Synthesis and characterization of dendritic compounds containing nitrogen: monomer precursors in the construction of biomimetic membranes.

In this article, we synthesized a novel dendritic 2-oxazoline, 2-(3,4,5-tris(4-dodecyloxybenzyloxy)phenyl)-4,5-dihydro-1,3-oxazole), and its amide precursor N-(2-hydroxyethyl)-3,4,5-tris(4-dodecyloxybenzyloxy)benzamide. Of the distinct synthetic routes explored, it was established that the direct amidation of esters with sodium methoxide followed by the dehydrative cyclisation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone as oxidizing agent and triphenylphosphine was the most efficient route to synthesize the dendritic 2-oxazoline. Besides, N-(2-hydroxyethyl)-3,4,5-tris(4-dodecyloxybenzyloxy)benzamide exhibited a monotropic columnar mesophase, whilst the dendritic 2-oxazoline does not exhibited a liquid crystalline mesophase. At the end, the first attempts to polymerize the 2-oxazoline monomer via cationic ring opening polymerization showed promising results. Therefore, the dendritic 2-oxazoline could be used as a mesogenic monomer in the synthesis of side-chain liquid-crystalline polyoxazolines that might self-assembly into columnar structures.

Membranes for Cation Transport Based on Dendronized Poly(Epichlorohydrin-Co-Ethylene Oxide). Part 2: Membrane Characterization and Transport Properties.

In this paper, we report on the preparation and characterization of membranes out of two side-chain liquid crystalline copolymers, dendronized at two different extents (20 and 40%, CP20 and CP40, respectively). The membranes were characterized by atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM), contact angle (CA) analysis, and water uptake. Moreover, transport properties were studied by methanol and proton conductivity experiment and by linear sweep voltammetry (LSV). For the sake of comparison, the behavior of the grafted copolymers was compared with the unmodified copolyether CP0 and with Nafion 117. Results demonstrated that in CP20 and CP40, cation transport depends on the presence of defined cationic channels, not affected by water presence; the comparison between LSV experiments performed with different alkaline cations suggests that CP40 possesses channels with larger diameters and better-defined inner structures.

Membranes for Cation Transport Based on Dendronized Poly(epichlorohydrin-co-ethylene oxide). Part 1: The Effect of Dendron Amount and Column Orientation on Copolymer Mobility.

Dendronized polyethers give rise to columnar LC structures which can successfully act as cation transport materials. Therefore, we prepared two different materials, based on Poly(epichlorohydrin-co-ethylene oxide) (PECH-co-EO) grafted with methyl 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy] benzoate, containing 20% or 40% modified units, respectively. The obtained polymers were characterized by differential scanning calorimetry (DSC), X-ray diffraction and optical microscopy between crossed polars (POM) and compared to the unmodified PECH-co-EO. In order to reach efficient transport properties, homeotropically oriented membranes were prepared by a fine-tuned thermal annealing treatment and were subsequently investigated by dynamic mechanical thermal analysis (DMTA) and dielectric thermal analysis (DETA). We found that the presence of the dendrons induces a main chain partial crystallization of the polyether chain and coherently increases the polymer Tg. This effect is more evident in the oriented membranes. As for copolymer orientation upon annealing, the cooling rate and the annealing temperature were the most crucial factors. DMTA and DETA confirmed that grafting with the dendron strongly hinders copolymer motions, but did not show great differences between unoriented and oriented membranes, regardless of the amount of dendrons.

Polymer Blends for Improved CO2 Capture Membranes.

We investigated the possibility of improving the performance of polysulfone (PSf) membranes to be used in carbon dioxide capture devices by blending PSf with a commercial polyethylene imine, Lupasol G20, previously modified with benzoyl chloride (mG20). Additive amount ranged between 2 and 20 wt %. Membranes based on these blends were prepared by phase inversion precipitation and exhibited different morphologies with respect to neat PSf. Surface roughness, water contact angles, and water uptake increased with mG20 content. Mass transfer coefficient was also increased for both N2 and CO2; however, this effect was more evident for carbon dioxide. Carbon dioxide absorption performance of composite membranes was evaluated for potassium hydroxide solution in a flat sheet membrane contactor (FSMC) in cross flow module at different liquid flow rates. We found that, at the lowest flow rate, membranes exhibit a very similar behaviour to neat PSf; nevertheless, significant differences can be found at higher flow rates. In particular, the membranes with 2 and 5 wt % additive behave more efficiently than neat PSf. In contrast, 10 and 20 wt % additive content has an adverse effect on CO2 capture when compared with neat PSf. In the former case, a combination of additive chemical affinity to CO2 and membrane porosity can be claimed; in the latter case, the remarkably higher wettability and water uptake could determine membrane clogging and consequent loss of efficiency in the capture device.

Diagnostic accuracy of C-reactive protein and erythrocyte sedimentation rate in patients with acute scrotum.

INTRODUCTION: Our aim was to investigate the diagnostic accuracy of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) in patients with acute scrotum. MATERIALS AND METHODS: One hundred and twenty patients with acute scrotum were evaluated and divided into 3 groups: 46 with acute epididymitis (group 1), 23 with spermatic cord torsion (group 2), and 51 with other noninflammatory causes of acute scrotum (group 3). Serum levels CRP and ESR were measured at the time of admission. RESULTS: Of the patients in group 1, 44 (95.6%) had elevated serum levels of CRP (mean, 67.77 +/- 47.80 mg/L). In contrast, only 1 patient in group 2 had a significant increase in the serum level of CRP (mean, 9.0 +/- 4.90 mg/L), and the patients in group 3 did not have any significant increase in the CRP levels (mean, 7.0 +/- 2.2 mg/L) (P < .001). The mean ESR values were 45.9 +/- 21.4 mm/h, 14.2 +/- 11.2 mm/h, and 8.8 +/- 7.5 mm/h, in groups 1 to 3, respectively (P < .001). The cutoff points for distinguishing between epididymitis and noninflammatory causes of acute scrotum were 24 mg/L for CRP and 15.5 mm/h for ESR. The sensitivity and specificity values were 93.4% and 100% for CRP and 95.6% and 85.1% for ESR, respectively. CONCLUSION: Based on our findings, serum levels of CRP and ESR can provide helpful information for differentiation between epididymitis and other causes of acute scrotum. We recommend CRP and ESR measurements before making a decision of surgical intervention.

Acute urinary retention in children.

PURPOSE: Acute urinary retention in children is a relatively rare entity. There are a variety of causes that are poorly defined in the literature. We review our cases of acute urinary retention in children at three major pediatrics centers in Iran. MATERIALS AND METHODS: Between 1996 and 2003, children (up to 14 years old) who had been referred due to acute urinary retention were examined. Urinary retention was defined as inability to empty the bladder volitionally for more than 12 hours with a urine volume greater than expected for age or a palpably distended bladder. All data from the patients' past medical history, physical examination, and laboratory and radiographic assessments were collected. Also, cystourethroscopy and urodynamic procedures had been carried out according to patient's conditions. Patients with secondary urinary retention, including those with surgical history, immobility or chronic neurological disorders, mental retardation, and drugs or narcotics consumption were excluded from study. RESULTS: There were 86 patients meeting the inclusion criteria, consisting of 58 males with a median age of 4 years (range 1 month to 14 years) and 58 females with a median age of 4 years (range 4 month to 14 years). Etiologies were lower urinary tract stone in 27.9%, neurological disorders in 10.4%, trauma in 10.4%, local inflammatory causes in 9.1%, urinary tract infection in 7.4%, ureterocele in 7.4%, benign obstructing lesions in 5.8%, iatrogenic in 5.8%, constipation in 4.6%, imperforated hymen in 3.5%, and large prostate utricle, urethral foreign body, and rhabdomyosarcoma each in 1 case (1.1%). CONCLUSION: The most common cause of acute urinary retention was lower urinary tract stone in our pediatric cases. Ureterocele and stone were the main findings in girls and boys, respectively, and urinary retention in boys was twice as prevalent as that in girls.