Correction to: Evaluation of gross-α, gross-β, U,Th and K values in groundwater and related health hazards: a case study,Arıklı mineralization area and its surroundings,Ayvacık, Çanakkale,Turkey

Journal of Radioanalytical and Nuclear Chemistry -     

A microfluidic microbial fuel cell array that supports long-term multiplexed analyses of electricigens

Microbial fuel cells (MFCs) are green energy technologies that exploit microbial metabolism to generate electricity. The widespread implementation of MFC technologies has been stymied by their high cost and limited power. MFC arrays in which device configurations or microbial consortia can be screened have generated significant interest because of their potential for defining aspects that will improve performance featuring high throughput characteristics. However, current miniature MFCs and MFC array systems do not support long-term studies that mimic field conditions, and hence, have limitations in fully characterizing and understanding MFC performances in varieties of conditions. Here, we describe an MFC array device that incorporates microfluidic technology to enable continuous long-term analysis of MFC performance at high throughput utilizing periodic anolyte/catholyte replenishment. The system showed 360% higher power output and 700% longer operating time when compared to MFC arrays without catholyte replenishment. We further demonstrate the utility of the system by reporting its successful use in screening microbial consortia collected from geographically diverse environments for communities that support enhanced MFC performance. Taken together, this work demonstrates that anolyte/catholyte replenishment can significantly improve the long-term performance of microfabricated MFC arrays, and support the characterization of diverse microbial consortia.     

Solution Properties and Chain Stiffness of Poly(Acenaphthylene)

Abstract

Solution properties of poly(acenaphthylene) (PACN) were investigated in a theta solvent (1,2-dichloroethane) and a good solvent (chloroform). The viscosity exponent α was found to be 0.50 at both 35 and 41 °C in 1,2-dichloroethane. Unperturbed dimensions found from viscometric measurements were compared with those of other vinyl aromatic polymers. Calculation of the chain flexibility parameters led to the conclusion that PACN is a rather stiff chain compared to other vinyl polymers with its characteristic ratio C∞ of 18.2 and chain flexibility parameter λ of 7.     

Multi-residue determination of organochlorine pesticides in vegetables in Kirklareli,Turkey by gas chromatography–mass spectrometry

The aim of this study was to investigate the level of organochlorine pesticides use for treatment of tomatoes, eggplants and cucumbers in Kirklareli, Turkey. Eighteen organochlorine pesticides were identified in vegetable samples using microwave or Soxhlet extraction, and results were obtained by gas chromatography–mass spectrometry. The optimized conditions were 1 mL/min for flow rate in the mobile phase, 1 μL for injection volume and 70 V for fragmentation potential. The analytical parameters show that the microwave oven extraction procedure provided the best results when compared to the Soxhlet extraction procedure. Samples were prepared for analysis with hexane?dichlormethane (1: 1, v/v, 40 mL) using a solid-phase extraction method. The limits of detection and quantitation for the eighteen analytes were between 0.02–0.26 and 0.06–0.87 μg/L, respectively, and the relative standard deviations of the migration time ranged from 2.4 to 8.9%. The recoveries of surrogate spiked in vegetable samples ranged from 70 to 116%, respectively. The obtained concentrations of pesticides in all vegetables studied were proved in the range of ND–123 μg/kg. The organochlorine pesticide sum was below the legal limit, except for Endrin and Methoxychlor, which requires a further elucidation of the organochlorine pesticides pollution sources in the region. These studies on accumulation of organochlorine pesticides were necessary for accomplishing a comprehensive ecological risk assessment.     

Acrylamide concentrations in grilled foodstuffs of Turkish kitchen by high performance liquid chromatography-mass spectrometry

For over ten years, there has been a considerable interest in determination of acrylamide in foodstuffs. It was known that both protein-rich and carbohydrates-rich foods cooked at high-temperatures can cause acrylamide formation. However, carbohydrates-rich foods such as potato chips and biscuit samples have been the common studied foods compared with protein-rich foods such as meat samples.In this study, determination of acrylamide in these two group foods was examined using HPLC-MS. For this purpose, firstly, the parameters that are thought to affect the response in the HPLC-MS analysis were optimized. The optimized conditions were found to be 0.3 ml min^{− 1} for flow rate of mobile phase, 40 µl for injection volume, 5 °C for column temperature and 70 V for fragmentor potential. The optimized method was applied for the determination of acrylamide levels in Turkish foodstuffs including grilled meat and chicken samples, potato chips, coffee and biscuit. The obtained concentrations for all studied foods were in the range of 20–250 µg kg^{− 1}. The results showed that acrylamide concentrations highly varied depending on the kind of food samples.     

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.     

Characterization and Miscibility Dynamics of Dextran-Poly(vinylpyrrolidone)-Water System

Summary: The miscibility behavior and intermolecular interactions among Dextran (Dx) with different molecular weight and Polyvinylpyrrolidone (PVP) blends were studied as dilute aqueous solutions at 25 °C by viscosity method. The intrinsic viscosity and the interaction coefficient were experimentally measured for each polymer-water as well as for Dx-PVP-water systems. These results served for the prediction of miscibility of the Dx/PVP blends with various blend compositions by using , , , , and parameters. Except Dx4/PVP with its all compositions (Dx4 with nominal molecular weight of 110 000), other blend systems are found to be almost miscible. The density measurements of these polymer solutions and their blends were conducted in order to compare with the viscosity findings. Lastly, all Dx with different molecular weight, PVP and their blends were characterized by infrared spectroscopy (FT-IR), and differential scanning calorimetry (DSC).     

A new approach to multivariate adaptive regression splines by using Tikhonov regularization and continuous optimization

This paper introduces a model-based approach to the important data mining tool Multivariate adaptive regression splines (MARS), which has originally been organized in a more model-free way. Indeed, MARS denotes a modern methodology from statistical learning which is important in both classification and regression, with an increasing number of applications in many areas of science, economy and technology. It is very useful for high-dimensional problems and shows a great promise for fitting nonlinear multivariate functions. The MARS algorithm for estimating the model function consists of two algorithms, these are the forward and the backward stepwise algorithm. In our paper, we propose not to use the backward stepwise algorithm. Instead, we construct a penalized residual sum of squares for MARS as a Tikhonov regularization problem which is also known as ridge regression. We treat this problem using continuous optimization techniques which we consider to become an important complementary technology and model-based alternative to the concept of the backward stepwise algorithm. In particular, we apply the elegant framework of conic quadratic programming. This is an area of convex optimization which is very well-structured, herewith, resembling linear programming and, hence, permitting the use of powerful interior point methods. Based on these theoretical and algorithmical studies, this paper also contains an application to diabetes data. We evaluate and compare the performance of the established MARS and our new CMARS in classifying diabetic persons, where CMARS turns out to be very competitive and promising.     

CMARS and GAM & CQP—Modern optimization methods applied to international credit default prediction

In this paper, we apply newly developed methods called GAM & CQP and CMARS for country defaults. These are techniques refined by us using Conic Quadratic Programming. Moreover, we compare these new methods with common and regularly used classification tools, applied on 33 emerging markets’ data in the period of 1980-2005. We conclude that GAM & CQP and CMARS provide an efficient alternative in predictions. The aim of this study is to develop a model for predicting the countries’ default possibilities with the help of modern techniques of continuous optimization, especially conic quadratic programming. We want to show that the continuous optimization techniques used in data mining are also very successful in financial theory and application. By this paper we contribute to further benefits from model-based methods of applied mathematics in the financial sector. Herewith, we aim to help build up our nations.