Sharif Digital Repository

Public concern over environmental issues such as ecosystem degradation is high. However, restoring coupled human-natural systems requires integration across many science, technology, engineering, management, and governance topics that are presently fragmented. Here, we synthesized 544 peer-reviewed articles published through September 2020 on the desiccation and nascent recovery of Lake Urmia in northwest Iran. We answered nine questions of scientific and popular interest about causes, impacts, stabilization, recovery, and next steps. We find: (1) Expansion of irrigated agriculture, dam construction, and mismanagement impacted the lake more than temperature increases and precipitation... 

Poly(lactic acid) (PLA)/poly(vinyl acetate-. co-vinyl alcohol) [P(VAc-. co-VA)] blends as new transparent film packaging materials were prepared at various blend compositions and different vinyl alcohol contents. The blends and pure PLA were irradiated by gamma rays to investigate the extent of changes in the packaging material during gamma ray sterilization process. The miscibility of the blends was dependent on the blend composition and vinyl alcohol content; gamma irradiation had little effect on the extent of miscibility. The glass transition temperature of pure PLA and PLA/P(VAc-. co-VA) miscible blends reduced after irradiation. On the other hand in PLA/P(VAc-. co-VA) immiscible... 

Background For decades, contrast agents have been used to reduce longitudinal (T1) or transverse (T2) relaxation times. High toxicity of gadolinium-based contrast agents leads researchers to new T1 contrast agents. Manganese oxide (MnO) nanoparticle (NP) with the lower peril and good enough signal change ability has been offered as a new possibility for magnetic resonance imaging (MRI). Methods The synthesized NPs were investigated for physicochemical and biological properties by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscope, dynamic light scattering (DLS), inductively coupled plasma, enzyme-linked immunosorbent assay, and 3 T magnetic resonance... 

Response surface methodology was used to investigate the effects of operating parameters such as impeller speed, binder mass and granulation time on the average size of granules produced in a lab scale conical high shear granulator. Two quadratic models were proposed to express granule mean size as a function of impeller speed and binder mass as well as impeller speed and granulation time. It was found out that in the studied domain, the influence of each parameter on granule size differs from one another. While increasing binder mass at constant quantity of powder increased the average size linearly, increasing impeller speed changed the mean size in accordance with quadratic trend. The... 

Four derivatives of hyaluronic acid (HA) bearing thiol (HA-SH), hydrazide (HA-hy), 2-dithiopyridyl (HA-SSPy), and aldehyde groups (HA-al) respectively were synthesized. Thiol and 2-dithiopyridyl as well as hydrazide and aldehyde make up two chemically orthogonal pairs of chemo-selective functionalities that allow in situ formation of interpenetrating (IPN) disulfide and hydrazone networks simultaneously upon the mixing of the above derivatives at once. The formation of IPN was demonstrated by comparing it with the formulations of the same total HA concentration but lacking one of the reactive components. The hydrogel composed of all four components was characterized by a larger elastic... 

Recently, hybrid graphene–quantum dot systems have attracted increasing attention for the next-generation optoelectronic devices such as ultrafast photo-detectors and solar energy harvesting. In this paper, a novel, one-step, reproducible, and solution-processed method is introduced to prepare hybrid graphene–PbS colloids by employing supercritical ethanol. In the hybrid nanocomposite, PbS quantum dots (~3 nm) are decorated on the reduced graphene oxide (rGO) nanosheets (~1 nm thickness and less than 1 micron lengths). By employing X-ray photoelectron and Raman and infrared spectroscopy techniques, it is shown that the rGO nanosheets are bonded to PbS nanocrystals through carboxylic bonds.... 

Heat curing was devised in temperature-controlled steam and water environments to synthesize reverse osmosis (RO) polyamide (PA) membrane. The effect of new curing media on the physicochemical properties and RO performance of the synthesized polyamides was fully investigated using X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared (ATR-IR), scanning electron microscopy (SEM), atomic force microscopy (AFM), and water drop contact angle. The results show a reduction in amide linkage content on the surface of the steam-cured polyamide and surface and bulk of the water-cured polyamide. Additionally, it was revealed that heat curing in the humidity-controlled environment... 

A regio- and diastereoselective synthesis of 2,3-dihydro-10b′ H -spiro[indeno[1,2- b ]quinoxaline-11,1′-pyrrolo[2,1- a ]isoquinoline]-2′,3′-diylbis(phenylmethanone) derivatives containing four contiguous chiral stereocenters was achieved through 1,3-dipolar cycloaddition of isoquinolinium N -ylides in a one-pot three-component reaction. The desired products were obtained in short reaction times and in moderate to high yields (up to 92%) under relatively mild reaction conditions. The structure and relative stereochemistry of the desired product was confirmed by X-ray diffraction analysis. © 2020 Georg Thieme Verlag. All rights reserved  

Therapeutic fragmented antibodies show a poor pharmacokinetic profile that leads to frequent high-dose administration. In the current study, for the first time, a novel proline, alanine, serine (PAS) repeat sequence called PAS#208 was designed to extend the plasma half-life of a nanosized anti-vascular endothelial growth factor-A single-domain antibody. Polyacrylamide gel electrophoresis, circular dichroism, dynamic light scattering, and electrophoretic light scattering were used to assess the physicochemical properties of the newly designed PAS sequence. The effect of PAS#208 on the biologic activity of a single-domain antibody was studied using an in vitro proliferation assay. The... 

Metal–organic frameworks (MOFs) have been widely used as porous nanomaterials for different applications ranging from industrial to biomedicals. An unpredictable one-pot method is introduced to synthesize NH2-MIL-53 assisted by high-gravity in a greener media for the first time. Then, porphyrins were deployed to adorn the surface of MOF to increase the sensitivity of the prepared nanocomposite to the genetic materials and in-situ cellular protein structures. The hydrogen bond formation between genetic domains and the porphyrin’ nitrogen as well as the surface hydroxyl groups is equally probable and could be considered a milestone in chemical physics and physical chemistry for biomedical... 

The present research comes up with a novel DNA-loaded poly-L-lysine (PLL)/hyaluronan (HA) nanocarrier (DNA-loaded PLL/HA NCs) for gene delivery applications, as a promising candidate for gene delivery into diverse cells. A straightforward approach was employed to prepare such a nanosystem through masking DNA-loaded PLL molecules by HA. Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), field emission-scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to analyse the interaction of the molecules as well as the physicochemical properties of the NCs. The NCs showed a negative charge of –24 ± 3 mV, with an average size of 138 ±... 

In recent years, the importance of capturing CO2 has increased due to the necessity of minimizing climate change and the detrimental effects of CO2 emissions from industrial processes. CO2 absorption, as one of the most mature carbon capture technologies, has been improved by introducing nanosized particles into liquid absorbents. Nanofluids have been the subject of interest in many studies recently due to their tremendous impact on absorption. This review comprehensively examines the CO2 absorption behavior for nanofluids through the investigation of different absorption systems. Potential mechanisms for improving the absorption/regeneration performance of nanoabsorbents as well as the... 

Unique physiochemical and biological properties of nanofibers along with the choice of a wide variety of materials for both fabrication and tunable release patterns make nanofibers an ideal option for drug delivery. Loading antibacterial agents into nanofibers has attracted great deal of attention. Whilst there are several studies focusing on applying new generations of antibacterial materials, antibiotics are still the gold standard in clinical applications. Therefore, we aimed at introducing antibiotic-loaded nanofiber substrates with potential for topical skin delivery applications, reduced consumption of antibiotics and increased storage time. We applied Amoxicillin (AMX) as a model drug... 

Herein, two distinct nanocomposites of CaTiO3 micro-cubes and polygonal SrFe12O19, both decorated with NiO nanoparticles, were successfully synthesized using hydrothermal method. The physico-chemical features of as-prepared samples were evaluated via XRD, FTIR, UV–vis, BET, XPS, FESEM and EDS analysis. Microwave attenuation features of as-prepared single layer absorbers were determined by VNA analysis in 2–18 GHz. Simulation confirmation was checked by preparing a bi-layer samples and evaluating it using VNA analysis after finding the appropriate thickness of each layer. The reflection loss from each single layer samples containing 20 wt% of each CaTiO3/NiO and SrFe12O19/NiO nanocomposites... 

Mn-doped ZnO nanoparticles, Zn1−xMnxO, were synthesised by a polyethylene glycol (PEG) sol–gel method and the physicochemical properties of compounds were characterised by atomic absorption spectroscopy (AAS), energy-dispersive X-ray analysis, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The catalytic degradation of an organic dye, methylene blue (MB), in the presence of Zn1−xMnxO as the catalyst and hydrogen peroxide (H2O2) as the oxidant at room temperature in water has been studied. Effects of oxidant, catalyst amount, catalyst composition, pH value of the solution and an OH-radical... 

Magnetic carbon nanotubes (MCNTs) have been widely studied for their potential applications in medicine, diagnosis, cell biology, analytical chemistry, and environmental technology. Introduction of MCNTs paved the way for the emergence of new approaches in nanobiotechnology and biomedicine as a result of their multifarious properties embedded within either the carbon nanotubes (CNTs) or magnetic parts. Numerous preparation techniques exists for functionalizing CNTs with magnetic nanoparticles, and these versatile strategies lay the ground for the generation of novel and versatile systems which are applicable to many industries and biological areas. Here, we review and discuss the recent... 

In this study, optimized cephalexin-loaded niosomal formulations based on span 60 and tween 60 were prepared as a promising drug carrier system. The niosomal formulations were characterized using a series of techniques such as scanning electron microscopy, Fourier transformed infrared spectroscopy, dynamic light scattering, and zeta potential measurement. The size and drug encapsulation efficiency are determined by the type and composition of surfactant. The developed niosomal formulations showed great storage stability up to 30 days with low change in size and drug entrapment during the storage, making them potential candidates for real applications. Moreover, the prepared niosomes showed... 

The present work is comprised of two main parts. In part 1 the Co-Ni/γ-Al2O3 catalyst was prepared using a sol-gel procedure. Then the effect of calcination variables including the calcination temperature and time on the catalytic performance for production of light olefins was investigated and optimized. The obtained results have shown that the catalyst which was calcined at 550 °C for 6 h has revealed the better catalytic performance for production of light olefins. In part 2 the effect of process conditions including the reaction temperature, H2/CO feed ratio and total reaction pressure on the catalytic performance (CO conversion%, (C2-C4) selectivity% and C5+ selectivity%) was... 

This study presents a bilayer structure as a skin scaffold comprised of an electrospun sheet layer made of polycaprolactone and polyvinil alcohol and a porous hydrogel layer made of chitosan and gelatin. The hydrogel layer was fabricated by employing the freeze-gelation technique. The bilayer structure was achieved by pouring the hydrogel solution on the electrospun sheet at the bottom of a mold followed by the freeze-gelation technique to obtain a porous structure in the hydrogel. The hydrogel and hydrogel-electrospun samples were characterized by scanning electron microscopy, swelling, tensile strength, in vitro and in vivo analyses. From a mechanical strength standpoint, the combination... 

Oxaliplatin (OXA) has been widely used for treatment of colorectal cancer. In this study, to enhance antitumor and apoptosis efficacy, OXA was encapsulated in a novel folate conjugated hyaluronic acid coated alginate nanogels (F/HA/AL/OXA). The F/HA/AL/OXA nanogels were prepared by cross-linking process. The physico-chemical properties of F/HA/AL/OXA nanogels were characterized using scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy, dynamic light scattering, and fluorescent spectrophotometry. The in-vitro antitumor activity of free OXA, AL, HA/AL, HA/AL/OXA and F/HA/AL/OXA nanogels were assessed using MTT assay against colorectal cancer...