Search results for "Diffuse"
showing 10 items of 276 documents
ChemInform Abstract: Coupled Semiconductor Systems for Photocatalysis. Preparation and Characterization of Polycrystalline Mixed WO3/WS2 Powders.
2010
Mixed WO3/WS2 powders were prepared by oxidation of WS2. The physical properties of the samples were characterized by X-ray diffraction, diffuse reflectance spectroscopy, and scanning electron microscopy; they were strongly dependent upon the time and temperature of oxidation. The chemical state and the elemental distribution of the sample surface were investigated by X-ray photoelectron spectroscopy. The photocatalytic results have showed that the aqueous suspensions of the mixed WO3/WS2 systems have significantly higher activities than pure WS2 and WO3 for the photodegradation of phenol. The enhanced performance can be related to the presence of heterojunctions WO3/WS2 on the single parti…
Dithionite bleaching of thermomechanical pulp: factors having effects on bleaching efficiency
2000
The efficiency of dithionite bleaching of Norway spruce (Picea abies) thermomechanical pulp was studied by applying various multivariate data analysis techniques to analytical data (temperature, pH, ion chromatographic and energy-dispersive X-ray fluorescence data). In addition, modeling the residual sulfur content of bleached pulp by means of diffuse reflectance UV-vis spectral data from laboratory-scale bleaching experiments was attempted. The results indicated that this lignin-preserving bleaching process could be evaluated by means of the analytical data using either PCR or PLS models. These models also indicated that wavelengths below 400 nm should not be used in measuring the pulp bri…
Application of solid-state electrochemistry techniques to polyfunctional organic–inorganic hybrid materials: The Maya Blue problem
2013
Abstract The time evolution of indigo plus palygorskite powdered mixtures during isothermal heating at different temperatures between 120 and 180 °C to form Maya Blue-type materials has been monitored by means of infrared spectrometry, diffuse reflectance spectrometry in the visible region and solid state electrochemical techniques. The kinetics of the formation process of such materials can be described in terms of two consecutive reactions, the first one consisting of the loss of zeolitic water of the palygorskite coupled with clay-indigo attachment and partial indigo to denydroindigo oxidation. The palygorskite dehydration acts as a rate-determining step fitting to a 3D Avrami-Erofe’ev k…
A new tool for direct non-invasive evaluation of chlorophyll a content from diffuse reflectance measurements
2017
Abstract Chlorophyll is a key biochemical component that is responsible for photosynthesis and is an indicator of plant health. The effect of stressors can be determined by measuring the amount of chlorophyll a , which is the most abundant chlorophyll, in vegetation in general. Nowadays, invasive methods and vegetation indices are used for establishing chlorophyll amount or an approximation to this value, respectively. This paper demonstrates that H-point curve isolation method (HPCIM) is useful for isolating the signal of chlorophyll a from non-invasive diffuse reflectance measurements of leaves. Spinach plants have been chosen as an example. For applying the HPCIM only the registers of bo…
Comparison of two vibrational procedures for the direct determination of mancozeb in agrochemicals.
2007
The direct determination of mancozeb in agrochemicals has been made by diamond attenuated total reflectance (ATR) Fourier transform infrared spectroscopy in the middle range (DATR-MIR) and diffuse reflectance infrared Fourier transform spectroscopy in the near range (DR-NIR) methods using in both cases a previous identification of the samples using a dendrographic classification and an appropriate partial least squares (PLS) calibration established from a set of nine external standards and optimized for each type of sample. It was analyzed a heterogeneous population of 11 samples obtained from the Spanish market, containing different co-formulated products, such as fosetyl-Al, copper oxychl…
A variant of the LRP4 gene affects the risk of chronic lymphocytic leukaemia transformation to Richter syndrome
2010
Richter syndrome (RS) represents the transformation of chronic lymphocytic leukaemia (CLL) to aggressive lymphoma. Risk factors of CLL transformation to RS are only partly known. We explored the role of the host genetic background as a risk factor for RS occurrence. Forty-five single nucleotide polimorphisms (SNPs) known to be relevant for CLL prognosis were genotyped in a consecutive cohort of 331 CLL, of which 21 had transformed to RS. After correcting for multiple testing and adjusting for previously reported RS risk factors, the LRP4 rs2306029 TT variant genotype was the sole SNP independently associated with a higher risk of RS transformation (Hazard Ratio: 4·17; P = 0·001; q = 0·047).…
Light-Tissue Interaction Model for the Analysis of Skin Ulcer Multi-spectral Images
2017
International audience; Skin ulcers (SU) are ones of the most frequent causes of consultation in primary health-care units (PHU) in tropical areas. However, the lack of specialized physicians in those areas, leads to improper diagnosis and management of the patients. There is then a need to develop tools that allow guiding the physicians toward a more accurate diagnosis. Multi-spectral imaging systems are a potential non-invasive tool that could be used in the analysis of skin ulcers. With these systems it is possible to acquire optical images at different wavelengths which can then be processed by means of mathematical models based on optimization approaches. The processing of those kind o…
Interim 18f-PDGPET for Aggressive Non-Hodgking's Lymphoma: A Systematic Review and Meta-Analysis
2011
Abstract Abstract 5183 Background: The advantage of using interim 18F-fluorodeoxyglucose (FDG) positron-emission tomography (PET) scan in the clinical work-up of patients with non-Hodgkin's lymphoma (NLH) is unclear. Data from meta-analyses are inconclusive, mainly because of the low number of patients evaluated and heterogeneity among studies. New clinical investigations, focused on this topic, have been recently published. We conducted an updated systematic review on the role of 18PDG-PET for the interim evaluation in patients with aggressive lymphomas. Materials and Methods: Medline, Embase, Scopus and Databases were searched for relevant studies through March 2011. We included studies t…
Structural and surface characterization of the polycrystalline system CrxOy · TiO2 employed for photoreduction of dinitrogen and photodegradation of …
1992
The polycrystalline system CrxOy-TiO2, used as a catalyst for photoreactions, was studied by X-ray diffractometric method, visible-ultraviolet diffuse reflectance and infrared spectroscopic methods, surface area determination, and porosimetry to characterize its structural and surface features. Two series of catalysts were prepared by two different methods, namely by coprecipitation and by impregnation. The first series was tested as photocatalysts for the dinitrogen photoreduction in a gas-solid regime and for the phenol photodegradation in a liquid-solid regime. The results indicate that the interaction of chromium ions with OH groups modifies the surface properties of the supports and co…