Selective IR response of highly textured phase change VO2 nanostructures obtained via oxidation of electron beam deposited metallic V films

We demonstrate the growth of highly textured VO2 nanocrystals via annealing of e-beam deposited amorphous metallic V. Temperature dependent ellipsometry results reveal the pronounced reflection near the IR spectrum above the transition and an almost temperature independent weak reflection in the visible spectrum. The IR reflection displays a strong hysteresis during heating and cooling near the transition temperature at 68 degrees C. indicating a first order transition and a strain-free structure. Our work demonstrates the feasibility to obtain high quality phase change nanostructures that transmit the visible spectrum but reflect IR and is suitable for large scale fabrication

Evaluation of nutritional status in pediatric intensive care unit patients: The results of a multicenter, prospective study in Turkey

IntroductionMalnutrition is defined as a pathological condition arising from deficient or imbalanced intake of nutritional elements. Factors such as increasing metabolic demands during the disease course in the hospitalized patients and inadequate calorie intake increase the risk of malnutrition. The aim of the present study is to evaluate nutritional status of patients admitted to pediatric intensive care units (PICU) in Turkey, examine the effect of nutrition on the treatment process and draw attention to the need for regulating nutritional support of patients while continuing existing therapies.Material and MethodIn this prospective multicenter study, the data was collected over a period of one month from PICUs participating in the PICU Nutrition Study Group in Turkey. Anthropometric data of the patients, calorie intake, 90-day mortality, need for mechanical ventilation, length of hospital stay and length of stay in intensive care unit were recorded and the relationship between these parameters was examined.ResultsOf the 614 patients included in the study, malnutrition was detected in 45.4% of the patients. Enteral feeding was initiated in 40.6% (n = 249) of the patients at day one upon admission to the intensive care unit. In the first 48 h, 86.82% (n = 533) of the patients achieved the target calorie intake, and 81.65% (n = 307) of the 376 patients remaining in the intensive care unit achieved the target calorie intake at the end of one week. The risk of mortality decreased with increasing upper mid-arm circumference and triceps skin fold thickness Z-score (OR = 0.871/0.894; p = 0.027/0.024). The risk of mortality was 2.723 times higher in patients who did not achieve the target calorie intake at first 48 h (p = 0.006) and the risk was 3.829 times higher in patients who did not achieve the target calorie intake at the end of one week (p = 0.001). The risk of mortality decreased with increasing triceps skin fold thickness Z-score (OR = 0.894; p = 0.024).ConclusionTimely and appropriate nutritional support in critically ill patients favorably affects the clinical course. The results of the present study suggest that mortality rate is higher in patients who fail to achieve the target calorie intake at first 48 h and day seven of admission to the intensive care unit. The risk of mortality decreases with increasing triceps skin fold thickness Z-score

Crossover of spectral reflectance lineshapes in Ge-doped VO2 thin films

Adjusting the insulator-to-metal transition (IMT) temperature of vanadium dioxide (VO2) thin films for use in optical applications can be achieved via doping with various elements. An important aspect, which was largely overlooked in the literature, is the change in the spectral reflectivity lineshapes upon dopant addition in order to control the critical temperature TC of VO2. Here, we demonstrate that the TC in VO2 can be varied effectively with Ge doping. Moreover, we observe that the spectral lineshapes of the Ge doped VO2 films reveal rather interesting characteristics, such as a distinct crossover in the high-reflection and low-reflection regions during the IMT that could allow frequency specific spectral functionalities

Morphology induced spectral reflectance lineshapes in VO2 thin films

In this work, we study the spectral reflectance of VO2 thin films and identify the specific contributions of the morphology and phase transition to optical spectra. The formation of highly [011] textured VO2 thin films on Si was achieved by an oxidation process starting with a metallic V thin film grown on an [001] Si substrate by an evaporation technique. Structural (XRD and Raman) and spectroscopic (XPS) characterization results indicate high purity VO2 formation with different sizes at various annealing temperatures without any change in the composition. Temperature dependent spectral reflectance distributions reveal that the insulator-to-metal transition (IMT) phase transition temperature of the VO2 nanostructures shows a slight size-dependence (approximate to 3 degrees C), but this feature can be overshadowed by morphology that can lead to the misinterpretation of transition characteristics. The spectral line shape of the reflectance curves in the visible and near-infrared regions show substantially different characteristics for the samples annealed at different temperatures. Using numerical scattering calculations, we conclude that the changes in the optical response can be explained by morphological effects instead of changes in the intrinsic material properties such as a shift in the IMT temperature. Furthermore, the main mechanism leading to different spectral line shapes is the morphological differences leading to diffuse and specular reflectance

Gamma irradiation, thermal conductivity, and phase change tests of the cement-hyperbranched poly amino-ester-block-poly cabrolactone-polyurathane plaster-lead oxide and arsenic oxide composite for development of radiation shielding material

The work which has been done on cement-polymer composite based shielding materials was comprehensively described in the present article, the choice of the study presented here is based on the choice of the researches. The new Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane Plaster-concrete composites mixed with different percentage soft lead oxide and arsenic oxide is used to research gamma-ray shielding and thermal conductivity characteristics. The synthesis of new Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane copolymer was achieved by Atom Transfer Reaction and Condensation Polymerization methods. The characterization of Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane Plaster was made with the Nuclear Magnetic Resonance, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry, Gel Permeation Chromatography, Thermogravimetric Analysis, Scanning Electron Microscope methods. The transmitted fluxes of gamma-rays that were emitted from Eu152 source was detected by a High Purity Germanium (HPGe) detector system at Karadeniz Technical University-Department of Physics in Trabzon and analyzed by a GammaVision (Version:6.07-Ortec, Oak Ridge, TN) computer program. The composite phase change materials including 89, 87, 69, 67% Portland cement, 1% and 3% PU-Plaster, 10% and 30% weight percent lead oxide and arsenic oxide was irradiated in the various gamma ray photon energy region (121.78, 344.28, 778.90, 964.08, 1085.87, 1112.07, and 1408.01 keV) for 3600 seconds. Then, linear attenuation coefficients, mass attenuation coefficients, half-value layer, tenth value layer, mean free path, radiation protection efficiency, and gamma-rays absorption of concrete-the Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane copolymers specimens were experimentally investigated. Thermal properties and morphological analysis of the irradiated substances were explored handling differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscope methods of the nano lead oxide and arsenic oxide including composite phase change material via gamma irradiation were submitted. Moreover, the effect of the Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane amount on the radiation attenuation of the composite material was investigated. Gamma attenuation experiments have been performed to specify lead equivalent values for the improved composite material. The composite equivalent thickness values from 0.5 to 0.6 cm sample thickness and 0.665 cm radius were obtained. Via crosschecking the acquired data from concrete samples with and without lead and arsenic, it was observed that, if the powder of lead oxide and arsenic oxide to cement ratio of 10% and 30% by weight is added in the concrete mixture, the concrete-the Hyperbranched Poly Amino-Ester-block-Poly Caprolactone-Polyurathane composite can be used as a suitable shield against gamma rays. Also, mass attenuation coefficients were calculated as theoretical with the National Institute of Standards and Technology(NIST)-XCOM database. The thermal conductivity coefficient and the heat capacity of the composites were determined