Development of a novel sandwich-structured composite from biopolymers and cellulose microfibers for building envelope applications.

A novel sandwich-structured composite was developed from the surface layers of polyhydroxyalkanoate (PHA) and the interlayer of polylactic acid (PLA)/cellulose microfibers (CMF) composite. Moreover, CMF was chemically modified via a sol-gel process to improve the compatibility between the natural reinforcement and the polymer matrix. According to the obtained results, the modified CMF exhibited a highly hydrophobic characteristic (contact angel value of approximately 118°), and they were homogeneously dispersed in the PLA matrix. The results of the thermogravimetric analysis indicated that the sandwich composites reinforced with the modified CMF showed improvement in thermal stability. Regarding the mechanical properties, the incorporation of the natural reinforcement into sandwich composites increased the values of tensile modulus and strength of materials. The water vapor permeability of sandwich composites increased with the addition of untreated fibers; however, the composites reinforced with the modified CMF showed superior barrier performance than that of untreated CMF. In addition, a durability test was performed to determine the effect of accelerated aging on the properties of sandwich composites. The results demonstrated that the mechanical and barrier properties of composites incorporated with untreated CMF decreased after the accelerated aging, whereas the composites reinforced with the modified CMF experienced the least change.

Assessment of knowledge and attitude of healthcare professionals regarding the use of telemedicine: A cross-sectional study from rural areas of Sindh, Pakistan.

Background: Telemedicine has proved its significance in the healthcare system, especially during the coronavirus disease 2019 (COVID-19) pandemic as it assists in the provision of early and effective healthcare to those in distant areas. This study aimed to assess the knowledge and attitude of healthcare professionals toward the use of telemedicine in the rural areas of Sindh, Pakistan. Materials and methods: The cross-sectional study was conducted with 212 healthcare professionals including physicians, consultants, surgeons, residents, dentists, and house officers working in public sector hospitals. The face-to-face method was used for data collection. Chi-square test and logistic regression analysis were applied to find the association between different variables and knowledge and practice of telemedicine using SPSS V 24. Results: The knowledge of participants regarding the usability of telemedicine and various tools used for the provision of medical services (video consultations, conferencing, use of applications, software, and online groups) was good. A total of 52.2% of participants showed agreement when they were questioned about being aware of online healthcare service provision. In this study, 52.8% of the participants practiced telemedicine by delivering healthcare services through online consultations. The majority of the participants were surgeons (25.9%), residents (23.1%), and physicians (18.9%). The internet (42.4%) and public media (25.9%) were the major sources of information for telemedicine. A total of 70.5% of participants suggested that strategies and efforts should be directed toward the enhanced implementation of telemedicine. Training in telemedicine as a source of information [OR = 13.02 (95% CI = 3.9-43.6), p < 0.001)] and awareness regarding the effect of telemedicine in healthcare quality [OR = 10.25 (95% CI = 2.9-35.4), p < 0.001)] remained the predicting factors for the practice of telemedicine among healthcare workers using multivariate regression analysis. Conclusion: Telemedicine has technologically revolutionized the medical sciences worldwide. The awareness level and usage of telemedicine were good among healthcare professionals in rural Sindh. Telemedicine should be utilized to provide quality healthcare in underprivileged areas by investing in infrastructure and education.

Varying magnetic field strength as an effective approach to boost up the plasma signal in laser-induced breakdown spectroscopy.

Externally variable magnetic field was incorporated with the combination of laser induced breakdown spectroscopy (LIBS) to enhance the emission characteristics of aluminum (Al) plasma. Significant emission enhancement of laser induced plasma (LIP) was obtained at different magnetic field strengths, for instance, enhancement factors of about 1.2, 1.3 and 1.4 times were observed at field-strength of 0.4, 0.5 and 0.6 T, respectively. The electron-impact excitation rates and recombination process were increased at higher field-strengths, which led to the higher emission signal due the stronger plasma confinement by the field. The electron number density and electron temperature were measured using the spectroscopic techniques at several delay times. At higher field strengths, both electron density and electron excitation temperature showed an increased trend as compared to the case when No-field was applied. Hence, the research has significance for enhancing the plasma signal which led to improve the LIBS sensitivity.

Quantification of Aluminum Gallium Arsenide (AlGaAs) Wafer Plasma Using Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS).

In this work, we report the results of the compositional analysis of an aluminum gallium arsenide (AlGaAs) sample using the calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique. The AlGaAs sample was doped with three various concentrations of gallium (Ga), arsenic (As), and aluminum (Al), as reported by the manufacturer, and the CF-LIBS technique was employed to identify the doping concentration. A pulsed Q-switched Nd: YAG laser capable of delivering 200 and 400 mJ energy at 532 and 1064 nm, respectively, was focused on the target sample for ablation, and the resulting emission spectra were captured using a LIBS 2000+ spectrometer covering the spectral range from 200 to 720 nm. The emission spectra of the AlGaAs sample yielded spectral lines of Ga, As, and Al. These lines were further used to calculate the plasma parameters, including electron temperature and electron number density. The Boltzmann plot method was used to calculate the electron temperature, and the average electron temperature was found to be 5744 ± 500 K. Furthermore, the electron number density was calculated from the Stark-broadened line profile method, and the average number density was calculated to be 6.5 × 1017 cm-3. It is further observed that the plasma parameters including electron temperature and electron number density have an increasing trend with laser irradiance and a decreasing trend along the plume length up to 2 mm. Finally, the elemental concentrations in terms of weight percentage using the CF-LIBS method were calculated to be Ga: 94%, Al: 4.77% and As: 1.23% for sample-1; Ga: 95.63%, Al: 1.15% and As: 3.22% for sample-2; and Ga: 97.32%, Al: 0.69% and As: 1.99% for sample-3. The certified concentrations were Ga: 95%, Al: 3% and As: 2% for sample-1; Ga: 96.05%, Al: 1% and As: 2.95% for sample-2; and Ga: 97.32%, Al: 0.69% and As: 1.99% for sample-3. The concentrations measured by CF-LIBS showed good agreement with the certified values reported by the manufacturer. These findings suggest that the CF-LIBS technique opens up an avenue for the industrial application of LIBS, where quantitative/qualitative analysis of the material is highly desirable.

Preparation of Breathable Cellulose Based Polymeric Membranes with Enhanced Water Resistance for the Building Industry.

This study focuses on the development of advanced water-resistant bio-based membranes with enhanced vapour permeability for use within building envelopes. Building walls are vulnerable to moisture damage and mold growth due to water penetration, built-in moisture, and interstitial condensation. In this work, breathable composite membranes were prepared using micro-fibrillated cellulose fiber (CF) and polylactic acid (PLA). The chemical composition and physical structure of CF is responsible for its hydrophilic nature, which affects its compatibility with polymers and consequently its performance in the presence of excessive moisture conditions. To enhance the dispersibility of CF in the PLA polymer, the fibers were treated with an organic phosphoric acid ester-based surfactant. The hygroscopic properties of the PLA-CF composites were improved after surfactant treatment and the membranes were resistant to water yet permeable to vapor. Morphological examination of the surface showed better interfacial adhesion and enhanced dispersion of CF in the PLA matrix. Thermal analysis revealed that the surfactant treatment of CF enhanced the glass transition temperature and thermal stability of the composite samples. These bio-based membranes have immense potential as durable, eco-friendly, weather resistant barriers for the building industry as they can adapt to varying humidity conditions, thus allowing entrapped water vapor to pass through and escape the building, eventually prolonging the building life.

Efficacy Of Phenylephrine Infusion Verses Colloid Preloading In Resolving Hypotension Due To Spinal Anaesthesia During Caesarean Section.

BACKGROUND: Spinal anaesthesia causes hypotension that is countered through various methods. Phenylephrine is a vasoconstrictor and haemocoel increases the intravascular vascular volume; both have an effect in preventing this hypotension; but their comparison has not been done in local setting. METHODS: Randomized control trial was conducted in month of June, 2017 at Ayub Teaching Hospital, Abbottabad. Block randomization with sealed envelopes was employed. Sample size was set at 90. Two equal groups were formed; Group A received 500 ml of haemocoel before spinal anaesthesia administration and Group B received 300µg of phenylephrine in 100ml infusion over 3 minutes.. RESULTS: An average drop of 8.2 mmHg, 9.7 mmHg and 3.1 mmHg in MAP was observed in Group A participants at 5 minutes, 10 minutes and 15 minutes respectively after spinal anaesthesia. In Group B, an average drop of 1.2mmHg was observed in first 5 minutes. MAP did not change significantly from this value throughout the monitoring period. There was a drop of 1.2 mmHg at 5 minutes in group B. After this, no further drop in blood pressure was observed. CONCLUSIONS: Phenylephrine infusion is better than haemocoel preload in preventing hypotension due to spinal anaesthesia.

Modification of hemp shiv properties using water-repellent sol-gel coatings.

For the first time, the hydrophilicity of hemp shiv was modified without the compromise of its hygroscopic properties. This research focused on the use of sol-gel method in preparation of coatings on the natural plant material, hemp shiv, that has growing potential in the construction industry as a thermal insulator. The sol-gel coatings were produced by cohydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) using an acidic catalyst. Methyltriethoxysilane (MTES) was added as the hydrophobic precursor to provide water resistance to the bio-based material. Scanning electron microscopy (SEM) and focused ion beam (FIB) have been used to determine the morphological changes on the surface as well as within the hemp shiv. It was found that the sol-gel coatings caused a reduction in water uptake but did not strongly influence the moisture sorption behaviour of hemp shiv. Fourier transformed infrared (FTIR) spectroscopy shows that the coating layer on hemp shiv acts a shield, thereby lowering peak intensity in the wavelength range 1200-1800 cm-1. The sol-gel coating affected pore size distribution and cumulative pore volume of the shiv resulting in tailored porosity. The overall porosity of shiv decreased with a refinement in diameter of the larger pores. Thermal analysis was performed using TGA and stability of coated and uncoated hemp shiv have been evaluated. Hemp shiv modified with sol-gel coating can potentially develop sustainable heat insulating composites with better hygrothermal properties.

Potentiation of the expression of cocaine-induced sensitization by a conditioned stressor.

Repeated exposures to physical stressors cross-sensitize to the locomotor activating effects of psychostimulants in rodents. In the present study, we examined the effect of a conditioned stressor on expression of cocaine-induced sensitization in rats. We determined whether a mint odor cue previously paired with footshock stress (FS) would elicit a sensitized locomotor response in cocaine pre-exposed rats. Rats were given once daily injections of cocaine (30 mg/kg, i.p.) or saline for 6 days in activity monitoring chambers. Subsequently, and in a different and distinct context, equal numbers of rats in each drug condition were exposed to 10 min of brief, intermittent FS or no FS, either in the presence or absence of the mint odor cue. Upon re-exposure to the activity chambers (in which cocaine exposures had been given), all rats previously exposed to cocaine showed robust conditioned locomotion. In response to a cocaine challenge (10 mg/kg, i.p.), cocaine relative to saline pre-exposed rats showed a sensitized locomotor response. Finally, in those cocaine pre-exposed rats that had been given prior odor-FS pairings, concurrent delivery of the cocaine challenge and presentation of the odor cue markedly potentiated the expression of sensitization. To our knowledge, this is the first report of a facilitation of cocaine-induced locomotor sensitization by a conditioned stressor.

Pattern-related visual stress, chromaticity, and accommodation.

PURPOSE: To investigate the impact of colored overlays on the accommodative response of individuals, with and without pattern-related visual stress (PRVS), a condition in which individuals manifest symptoms of perceptual distortion and discomfort when viewing a 3-cyc/deg square-wave grating. METHODS: Under double-masked conditions, 11 individuals who reported PRVS selected an overlay with a color individually chosen to reduce perceptual distortion of text and maximize comfort (PRVS group). Two groups of control subjects individually matched for age, sex, and refractive error were recruited. Control group 1 similarly chose an overlay to maximize comfort. Control group 2 used the same overlays as the paired PRVS participant. The overlay improved reading speed by 10% (P < 0.001), but only in the PRVS group. A remote eccentric photorefractor was used to record accommodative lag while participants viewed a cross on a background. The background was uniform or contained a grating and was either gray or had a chromaticity identical with that of the chosen overlay. There were therefore four backgrounds in all. RESULTS: Overall, the accommodative lag was 0.44 D greater in the participants with PRVS. When the background had the chosen chromaticity, the accommodative lag was reduced by an average of 0.16 D (P = 0.03) in the PRVS group, but not in the symptom-free groups: in control group 2 the colored background slightly increased the accommodative lag. CONCLUSIONS: Accommodative lag was greater in individuals susceptible to pattern-related visual stress and was reduced by a colored background.