Studying the Role of Sirtuin-1 Gene in the Maintenance of Mouse Intestinal Epithelium

Sirtuin-1 (Sirt-1), an NAD+-dependent deacetylase, maintains energy homeostasis upon stress-induced decline in energy levels. Sirt-1 possesses many other functions ranging from regulating cellular proliferation and apoptosis to maintaining glucose and lipid metabolism. By deacetylating its target proteins, Sirt-1 can also increase the lifespan of lower organisms such as yeast, flies, and worms. However, lifespan-prolonging ability of Sirt-1 in rodent models and human subjects has been investigated, exhibiting only partially promising results. Contrary to its role in increasing lifespan in rodents and humans, Sirt-1 has exhibited positive results on prolonging the health-span of these model organisms by delaying or inhibiting the development of diseases and disorders that present themselves with increasing age. Drug mediated Sirt-1 activation via resveratrol and Sirt-1 activation through calorie restriction were shown to bring a healthy balance to glucose and lipid metabolism especially in rodents fed on high-fat diet. Currently, Sirt-1 is investigated as a target gene for the treatment of Type-2 Diabetes in multiple clinical trials. In this study, we investigated the role of the Sirtuin-1 in the maintenance of intestinal epithelium. In our study, we utilized intestinal organoid models grown from isolated crypts of mouse small intestine. We performed knockdown of Sirt-1 at mRNA level via lentiviral shRNA. Additionally, we targeted Sirt-1 activity by applying resveratrol to the culture media of mouse intestinal organoids. Our main aim was to address how manipulations of Sirt-1 expression or activity would affect the function of intestinal stem cells and Paneth cells located in the crypt tips of intestinal organoids. Furthermore, we were interested in how these changes would alter organoid viability and crypt regeneration. In this study, we demonstrate that Sirt-1 is a fundamental gene for mouse intestinal organoid viability as well as organoid crypt regeneration. We also show that Sirt-1 controls crypt regeneration by regulating Paneth cell differentiation and thus intestinal stem cell niche conditions in the crypt bottoms of mouse intestinal organoids. Activation of Sirt-1 by resveratrol decreases total Paneth cell number in a crypt bottom leading to the relative retardation of crypt regeneration as well as the reduction in crypt size. High concentrations of resveratrol resulted in death of intestinal organoids, probably due to complete loss of Paneth cells

Nanowire geometry effects on devices and transport mechanisms: SnS2/SiNW heterojunction

The semiconductor nanowire technology has become essential in developing more complex and efficient devices. In this study, the Si nanowire (SiNW) heterojunction structure with a two-dimensional SnS2 thin film was investigated. The SiNW array was created by the metal-assisted etching method because of length control and production over large areas of nanowires. The created SiNW has more diminishing reflectivity compared with Si planar substrate. The diode characteristics of SnS2/SiNW and SnS2/Si planar heterojunctions were investigated by dark current analysis at room temperature, and the improving diode characteristics by the three-dimensional interface between SiNW and SnS2 thin film were discussed. Transport mechanisms of the SiNW heterojunction were also studied for various methods. Thermionic emission and thermally assisted tunneling models are the dominant mechanisms for low voltages (0.02–0.20 V), and the space charge limiting current mechanism dominates the current for comparingly high voltages (0.20–0.40 V). All the values reveal the significant impact of the SiNW on heterojunctions for improving efficiency

Effects of Substrate Temperature on material characteristics of sputtered Aluminum doped ZnO thin films

Transparent conductive layers (TCOs) attract the attention in opto-electronic and photovoltaic device applications due to their conductivity and transparency characteristics in the visible region of the solar spectrum. There are various TCO thin film layers, and indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) are the most popular thin films such as the desired material characteristics of SnO2and ZnO, respectively. In literature, the works indicated that the characteristics of these films can be changed by using different deposition techniques. In this work, sputtering technique was used to fabricate the AZO film samples. AZO film samples were deposited on the ultrasonically cleaned commercial soda lime glass substrates at the substrate temperature of 300-573 K. The samples were fabricated by using DC/RF magnetron sputtering system. In general, the work was concentrated on the structural, electrical and optical properties of the AZO thin films with respect to the substrate temperature. In addition, post-annealing processes were applied to investigate the annealing effect on the material properties. The characterizations of thethin films were done by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) for structural analysis, UV/Vis transmission measurements for optical analysis and dark conductivity measurements for electrical analysis. In XRD spectra, all the deposited thin films were found highly oriented in the (002) orientation direction. By using transmission values, band gap energies of the films were investigated under the effect of substrate and annealing temperature. According to corresponding Tauc plots, the value of the band gap of AZO thin films increased with increasing deposition temperature. In addition, electrical measurements were done by four-point probe system and the electrical resistivity of the AZO films were quite sensitive to the substrate temperature and the value of resistivity values were found in decreasing behavior with increasing deposition temperature

Optical and Nanomechanical Properties of Ga(2)Se(3)Single Crystals and Thin Films

The optical and nanomechanical properties of Ga(2)Se(3)single crystals and thin films were investigated using reflection, transmission, and nanoindentation measurements. The reflection spectrum recorded in the 525- to 1100-nm range was analyzed to get the band gap energy of the crystal structure, and derivative analysis of the spectrum resulted in band gap energy of 1.92 eV which was attributed to indirect transition. The band gap energy of thermally evaporated Ga(2)Se(3)thin film was determined from the analysis of the transmittance spectrum. The absorption coefficient analysis presented the direct band gap energy as 2.60 eV. The refractive index was investigated in the transparent region using the Wemple-DiDomenico single-oscillator model. Nanoindentation measurements were carried out on the crystal and thin film structures of Ga2Se3. Nanohardness and elastic modulus of the Ga(2)Se(3)single crystals and thin films were calculated following the Oliver-Pharr analysis method

Water Impact Resistant and Antireflective Superhydrophobic Surfaces Fabricated by Spray Coating of Nanoparticles: Interface Engineering via End-Grafted Polymers

Fully transparent and water impact resistant superhydrophobic coatings are of great importance for a range of applications including photovoltaics, photonics, automotive windshields, and building windows. A widely utilized approach to fabricate such coatings involves solution-based deposition of hydrophobic nanoparticles. A central challenge is that these coatings do not simultaneously offer high levels of water repellency, perfect transparence, and water impact resistance. Here we demonstrate that end-grafted polymers present excellent interfaces for spray-coated hydrophobic nanoparticles and enable fabrication of water impact resistant and antireflective superhydrophobic coatings (SHPARCs). Depending on the backbone chemistry and thickness, end-grafted polymers uniquely interacted with the fluorinated nanoparticles, resulting in nanostructured films that provided reduction of reflective losses and protection from the impact of water droplets. Counterintuitively, substrates modified with end-grafted hydrophilic polymers exhibited high water impact resistance: the sliding angle of SHPARC on 12 nm thick end-grafted poly(ethylene glycol) layer was <2 degrees after exposure to 100000 water droplets. SHPARC increased the transparency of the glass substrate by similar to 5% through omnidirectional antireflectivity. We finally demonstrate application of SHPARC on a large area (156 x 156 mm(2)) silicon solar cell without significant (<0.23%) reduction of the power conversion efficiency, illustrating the promise of the presented approach in fabrication of self-cleaning photovoltaic modules

The Correlation of Cord Arterial Blood Gas Analysis Results and Apgar Scores in Term Infants Without Fetal Distress

Objective: This study aimed to evaluate the necessity of cord arterial blood gas analysis in cases without fetal distress and normal Apgar score