A Solid Phase Extraction Application of Hybrid Nano B_2O_3/ZrO_2 for Separation and Determination of Trace Indium in Environmental Samples

Hybrid nanomaterials have attracted considerable interest in environmental science, analytical chemistry and atomic spectroscopy. In the present study, a column solid phase extractioo procedure was developed for the separation and preconcentration of indium in various matrixes by using hybrid nanomaterial B₂O₃/ZrO₂ (HNMBZ). Various experimental and analytical parameters such as sample solution pH, sample solution volume, flow rate of sample solution and eluent, volume and concentration of eluent aod amount of HNMBZ, effect of common matrix ions and capacity of sorbent were investigated. The adsorbed metal ions on HNMBZ were eluted with 6 mL of 1 mol·L-1 HNO₃ solutions and their concentrations were determined by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Under the optimized conditions, detection limits for indium for 3 pixels and 5 pixels were found as 0.20 and 0.16 μg·L-1, respectively. The accuracy of the procedure was checked by spiked water samples. The developed procedure was successfully applied to real samples for the separation and determination of indium.     

Surface relief diffraction gratings fabricated in ZnSe by frequency doubled Nd:YAG laser micromachining

A novel and rapid laser ablation method for the fabrication of diffractive optical elements (DOE) in ZnSe that takes advantage of the relatively low intensity damage threshold of the material is presented. The structures were characterized in terms of their shape and diffraction efficiency at normal incidence under 10.6 μm radiation for TE and TM polarizations. Sample surface polishing as well as the possible effect of the melted zone and structural modification of the material around the ablated region on the power transmission capability of the grating are also discussed.     

Development of a Financial Performance Index for Hospitals: DEA Approach

This paper presents an innovative method of measuring and assessing financial performance for hospitals using data envelopment analysis (DEA). A 6% national sample of acute care hospitals was used to compare conventional ratio analysis with the financial performance index (FPI), an aggregate measure of financial performance, developed in this study. The results showed that FPI has captured what various financial ratios indicate independently. The development of a FPI across many financial ratios eases the comparison of an individual hospital with its peers. Development and uses of a FPI can also be applied to other industries.     

Deconvolution of evoked responses obtained at high stimulus rates

Continuous loop averaging deconvolution (CLAD) is a new general mathematical theory and method developed to deconvolve overlapping auditory evoked responses obtained at high stimulation rates. Using CLAD, arbitrary stimulus sequences are generated and averaged responses deconvolved. Until now, only a few special stimulus series such as maximum length sequences (MLS) and Legendre sequences (LGS) were capable of performing this task. A CLAD computer algorithm is developed and implemented in an evoked potential averaging system. Computer simulations are used to verify the theory and methodology. Auditory brainstem responses (ABR) and middle latency responses (MLR) are acquired from subjects with normal hearing at high stimulation rates to validate and show the feasibility of the CLAD technique.     

Photocatalytic activities of poly(methyl methacrylate)/titanium dioxide nanofiber mat

This study aimed to evaluate the photocatalytic activities of poly(methyl methacrylate) (PMMA)/titanium dioxide (TiO₂) nanofiber mat. TiO₂ nanoparticles in crystal phase were first prepared by sol-gel process and then PMMA/TiO₂ nanofiber mat was prepared through electrospinning. The composite (PMMA/TiO₂) nanofiber mat was compared with that of pure PMMA nanofiber mat through performing FTIR and UV-Vis spectroscopy, scanning electron microscopy, thermogravimetric analysis, weight loss and water contact angle measurements. The photocatalytic activity of PMMA/TiO₂ nanofiber mat was evaluated by investigating both the photocatalytic decomposition of a model dye, methylene blue, and photocatalytic degradation of the composite nanofiber mat in the ambient air under ultraviolet light irradiation.     

Residue Analysis and Determination of IMI Herbicides in Sunflower and Soil by GC–MS

Sunflower agriculture is an important subsector that plays a key role in the economy of Turkey, contributing 1.38 million tonnes. The aim of this study is to investigate the levels of imidazolinone (IMI) group herbicides in Thrace Region, Turkey. In particular, we aimed to determine the residue levels of imazamox, a herbicide used in sunflower production in Thrace Region, in soil, different parts of plant, and seed. Five herbicides were identified in sunflower samples using solid–liquid extraction with gas chromatography–electrospray ionization mass spectrometry (GC–EI–MS) on single-quadruple instruments in selected ion monitoring (SIM) mode. The optimized conditions were found to be mobile-phase flow rate of 1 mL min^?1 and injection volume of 3 μL in programmed temperature vaporization (PTV) solvent vent mode. The recovery of imazamox, imazaquin, imazethapyr, imazapyr, and imazapic from sunflower plant and soil was 89 and 99, 104 and 105, 92 and 93, 96 and 92, and 99 and 96%, respectively.     

Contents of selected B vitamins in NIST SRM 3280 multivitamin/multielement tablets by liquid chromatography isotope dilution mass spectrometry

There is increased interest in accurately assessing the total dietary intake of vitamins from all sources, including foods and dietary supplements. Consequently, a Dietary Supplement Ingredient Database (DSID), based upon analytical values, is being established by USDA with support of the Office of Dietary Supplements (ODS), NIH. The DSID necessitated the development of a new SRM, 3280 — Multivitamin/Multimineral Tablets, by the National Institute of Standards and Technology (NIST), with support from the ODS. As a continuation of a long-term project to develop and validate new methods of determining water-soluble B vitamins in foods and dietary supplements, and as part of a collaborative effort with NIST to characterize SRM 3280, values for the vitamin contents of SRM 3280 have been generated by a liquid chromatographic isotope dilution mass spectrometric (LC/IDMS) method. Isotope-labeled (¹³C and/or ²H) B vitamins (B1-thiamine, B6-pyridoxine, B3-nicotinamide, and B5-pantothenic acid) were obtained from commercial sources, with the support of the ODS/NIH. Our LC/IDMS method uses a C18 reversed phase column, an Agilent 1100 HPLC system, and a Quattro Micro triple-quad mass spectrometer (MS). B vitamin determination was achieved using a gradient LC profile combined with MS/MS detection in multiple reaction monitoring mode. Stock solutions of the isotope-labeled vitamins were calibrated against USP standard solutions. The SRM tablets, with added amounts of the four isotope-labeled B vitamins, were extracted and the vitamins simultaneously determined in a single LC run, in contrast with the single-component determinations performed via IDMS. Unknown vitamin concentrations were calculated by comparing the ratios of the integrated LC peaks at the different masses of the unlabeled and labeled vitamins.     

Photocatalytic activity of polyvinyl borate/titanium dioxide composites for UV light degradation of organic pollutants

In this study, it is aimed to prepare polyvinyl borate (PVB)/titanium dioxide (TiO₂) composites through the condensation reaction of polyvinyl alcohol and boric acid in the presence of TiO₂ nanoparticles. The scope of this study contains the photocatalytic activity of the prepared composites with varying TiO₂ content from 0 to 35 wt.% for the degradation of methylene blue in aqueous medium under UV light irradiation. The structure and morphological properties of the prepared composites were studied with FTIR, TGA, EDX, SEM and TEM analyses. The photocatalytic activity of the prepared samples was analyzed by UV-Vis spectrophotometer measurements. In parallel with TiO₂ content up to 30 wt.%, the photocatalytic activity of PVB/TiO₂ composites was enhanced and the composites exhibited higher discoloration rate of the model dye, methylene blue.     

Provider experience and technical efficiency in the treatment of stroke patients: DEA approach

This study uses Data Envelopment Analysis to examine relationships between provider experience and technical efficiency in stroke treatment patients. Using 214 hospitals grouped according to stroke treatment experience, the study examines how the inputs—average length of stay (ALOS), occupational and physical therapy charges, and all other charges—are combined to treat mild and severe stroke cases. This study finds that, on average, technical efficiency improves with experience. However, although more experienced providers are on average deemed more technically efficient, they tend to have higher charges. The study further illustrates that the gap in case severity between efficient and inefficient providers widens as experience level increases. These findings suggest there is great potential for inefficient providers to alter practice patterns to those similar to efficient providers, in order to significantly reduce aggregate expenditures.     

Synthesis and oxoanions (dichromate/arsenate) sorption study of N-methylglucamine derivative of calix[4]arene immobilized onto poly[(phenyl glycidyl ether)-co-formaldehyde]

The article describes synthesis as well as the evaluation of sorption properties of new N-methylglucamine substituted calix[4]arene and its poly[(phenyl glycidyl ether)-co-formaldehyde] immobilized product. Firstly, 5,17-bis-[(N-methylglucamine)methyl]-25,26,27,28-tetrahydroxy-calix[4]arene (3) was synthesized by the treatment of calix[4]arene with a secondary amine N-methylglucamine and formaldehyde via Mannich reaction. The immobilization of 3 onto poly[(phenyl glycidyl ether)-co-formaldehyde] to form calixarene based polymer (4) was carried out under suitable reaction conditions via nucleophilic substitution reaction. All the new compounds were characterized by a combination of FT-IR, ¹H-NMR spectroscopic and elemental analysis techniques. The sorption studies of 4 reveal that it is an excellent material for the removal of toxic oxoanions especially arsenate from aqueous environment. To understand the selectivity of 4, we also examined the retention of dichromate anions in the presence of Cl^?, NO₃ ^? and SO₄ ^2? anions at pH 1.5.