Low velocity impact response of autoclaved aerated concrete/CFRP sandwich plates

Autoclaved aerated concrete (AAC)-CFRP composites have proven to be structurally efficient combinations for lightweight structural components such as floor beams, lintels, walls or columns. Besides the need to possess adequate flexural properties, AAC/CFRP structures need to be evaluated for their ability to withstand localized damage. During service, the before mentioned structural members are subjected to impact loading that varies from localized object impact, blast due to explosions, or to high velocity impact of debris during tornados, hurricanes, or storms. The objective of this paper is to evaluate the response of AAC/CFRP sandwich structures to low velocity impact (LVI) and to compare the experimental results to the predicted energy absorptions values given by an energy balance model. AAC/CFRP panels are prone to heavy object impacts under relatively low velocities such as in the case of object/tool drops on floor beams or low velocity collisions against columns.     

Oxygen‐releasing biomaterials for tissue engineering

Due to the increasing demand to generate thick and vascularized tissue‐engineered constructs, novel strategies are currently being developed. An emerging example is the generation of oxygen‐releasing biomaterials to tackle mass transport and diffusion limitations within engineered tissue constructs. Biomaterials containing oxygen‐releasing molecules can be fabricated in various forms, such as hybrid thin films, microparticles or three dimensional scaffolds. In this perspective, we summarize various oxygen‐releasing reagents and their potential applications in regenerative engineering. Moreover, we review the main approaches for fabricating oxygen‐releasing biomaterials for a range of tissue engineering applications. © 2013 Society of Chemical Industry     

Development of benchmark wind speed for Gharo and Jhimpir,Pakistan

This paper deals with the development of benchmark wind speed values for different regions at different height levels in Gharo – Keti bandar wind corridor in the south of Pakistan. Unavailability of reliable long term historical wind data had made many uncertainties to project development activities because of unsteady nature of wind. This situation has resulted in realizing the importance of development of the benchmark wind speed values for the development of wind energy sector in Pakistan. Thus Government of Pakistan has introduced an innovative concept of Wind Risk by guaranteeing the wind speeds as given in benchmark wind speed table and has consequently diluted the financial risks of project developers involved in execution of wind power projects in Pakistan. Developing countries that do not have long term wind data, can be benefited from this study to establish wind energy in their country on fast track basis by pursuing same path. This will lead to the creation of new wind energy markets in the world.     

Facile One‐Step Micropatterning Using Photodegradable Gelatin Hydrogels for Improved Cardiomyocyte Organization and Alignment

Hydrogels are often employed as temporary platforms for cell proliferation and tissue organization in vitro. Researchers have incorporated photodegradable (PD) moieties into synthetic polymeric hydrogels as a means of achieving spatiotemporal control over material properties. In this study protein‐based PD hydrogels composed of methacrylated gelatin and a crosslinker containing o‐nitrobenzyl ester groups are developed. The hydrogels are able to degrade rapidly and specifically in response to UV light and can be photopatterned to a variety of shapes and dimensions in a one‐step process. Micropatterned PD hydrogels are shown to improve cell distribution, alignment, and beating regularity of cultured neonatal rat cardiomyocytes. Overall this work introduces a new class of PD hydrogel based on natural and biofunctional polymers as cell culture substrates for improving cellular organization and function.     

Three-level response surface full-factorial design: advanced chemometric approach for optimizing diclofenac sodium-imprinted polymer

The present research work was undertaken to optimize the template:monomer:cross-linker ratio of the diclofenac sodium block molecularly imprinted polymer with respect to the molecular recognition properties. A three-level full-factorial design was employed. This is of great interest because applying this approach instead of traditional methods would be expected to improve validation of the optimum and consumed time. Imprinted polymers with selected ratios and the control polymers were synthesized by precipitation polymerization method and the values of rebind capacity and imprinting factor calculated after performing batch rebinding experiments. The predicted optimum ratios of (1:8:40) and (1:4:40) were found by applying the three-dimensional surface plots for rebind capacity and imprinting factor. The optimized imprinted polymers and their control polymers were produced. These polymers were evaluated using equilibrium binding experiments and finally the optimum molar ratio of (1:8:40) chosen. Batch rebinding experiments were carried out to evaluate the binding and selectivity properties of the optimized polymer. A heterogeneous nature of the binding sites was found based on the Scatchard plot. The selectivity study of imprinted polymers demonstrated a 24 % cross-reactivity towards meclofenamate sodium, but less than 2 % towards fenoprofen calcium.     

Melt extrusion of polyethylene nanocomposites reinforced with nanofibrillated cellulose from cotton and wood sources

Replacing petroleum‐based materials with biodegradable materials that offer low environmental impact and safety risk is of increasing importance in sustainable materials processing. The objective of this study was to produce uniform nanofibrillated cotton from recycled waste cotton T‐shirts using microgrinding techniques and compare its performance as reinforcing agent in thermoplastic polymers constructs with wood‐originated materials. The effect of the microgrinding process on morphology, crystallinity, and thermal stability of materials was evaluated by transmission electron microscopy (TEM), scanning electron microscope (SEM), X‐ray diffraction (XRD), and thermogravimetry analysis (TGA). Nanofibrillated cotton resulted in higher crystallinity and thermal stability than fibrillated bleached and unbleached softwood. All the materials were extruded with low‐density polyethylene to fabricate nanocomposite films. Nanofibrillated cotton nanocomposites had a higher optical transparency than did the wood‐based composites. The mechanical properties of the nanofibrillated cotton nanocomposites were largely improved and showed 62.5% increase in strength over the wood‐based nanofibrillated containing composites, in agreement with the higher crystallinity of the nanosized cotton‐derived filler material. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41857.     

Arterial thrombosis: a complication of loop ileostomy

Maternal thyrotoxicosis complicates approximately 0.2% of pregnancies. Simultaneous occurrence of maternal and fetal thyrotoxicosis during labor is rare, and control of maternal tachycardia and hypertension, as well as fetal manifestations of thyrotoxicosis, are cornerstones of management. An 18-year-old nulliparous female at 33 weeks gestational age presented in labor with thyrotoxicosis. Fetal tachycardia was present as well. Labetalol therapy resulted in a decrease in maternal pulse and blood pressure, and resolution of fetal tachycardia. Vaginal delivery occurred. Subsequent evaluation demonstrated neonatal thyrotoxicosis and high maternal titers of thyroid-stimulating immunoglobulin. In conclusion, labetalol was beneficial in the treatment of maternal and fetal thyrotoxicosis during labor.     

Measurement of the leaching rate of radionuclide Cs from the solidified radioactive sources in Portland cement mixed with microsilica and barite matrixes

Portland cement was mixed with radionuclide ¹³⁴Cs to produce low-level radioactive sources. These sources were surrounded with cement mixed with different materials like microsilica and barite. The leaching rate of ¹³⁴Cs from the solidified radioactive source in Portland cement alone was found to be 4.481 × 10⁻⁴ g/cm² per day. Mixing this Portland cement with microsilica and with barite reduced significantly the leaching rate to 1.091 × 10⁻⁴ g/cm² per day and 3.153 × 10⁻⁴ g/cm² per day for 1 wt.% mixing, and to 1.401 × 10⁻⁵ g/cm² per day and 1.703 × 10⁻⁴ g/cm² per day for 3 wt.% mixing, respectively. It was also found that the application of a latex paint reduced these leaching rates by about 6.5%, 20.3% and 13.3% for Portland cement, cement mixed with microsilica and with barite, respectively. The leaching data were also analyzed using the polynomial method. The obtained results showed that cement mixed with microsilica and with barite can be effectively used for radioactive sources solidification.     

Physical,mechanical, and transdermal diltiazem release analysis of nanosilica tailored various poly(vinyl alcohol) membranes

Hybrid membranes based on poly(vinyl alcohol) (PVA) of widely different molecular weights and ex situ nanosilica were synthesized and characterized as transdermal delivery device for Diltiazem hydrochloride. Investigations showed that change in PVA molecular weight strongly influenced physico‐mechanicals of the hybrids especially at low nanosilica content than at higher levels. As for example at 1 wt %, low molecular weight PVA induced finer dispersion of silica nanoparticles resulting into higher dry state crystallinity and mechanical strength but slightly lower biocompatibility as compared to high molecular weight PVA. Those variations in physico‐mechanicals finally affected Diltiazem retention and its elution from those membranes under physiological conditions. Low molecular weight PVA produced highest drug retention as well as slowest yet steady release than both high molecular weight PVA and neat PVA membranes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2076–2086, 2013