Antibacterial activities of essential oils and extracts of Turkish Achillea,Satureja and Thymus species against plant pathogenic bacteria

BACKGROUND: The aims of this study were to examine the chemical composition of the essential oils and hexane extracts of the aerial parts of Satureja spicigera (C. Koch) Boiss., Thymus fallax Fisch. & CA Mey, Achillea biebersteinii Afan, and Achillea millefolium L. by GC and GC–MS, and to test antibacterial efficacy of essential oils and n‐hexane, chloroform, acetone and methanol extracts as an antibacterial and seed disinfectant against 25 agricultural plant pathogens. RESULTS: Thymol, carvacrol, p‐cymene, thymol methyl ether and γ‐terpinene were the main constituents of S. spicigera and T. fallax oils and hexane extracts. The main components of the oil of Achillea millefolium were 1,8‐cineole, δ‐cadinol and caryophyllene oxide, whereas the hexane extract of this species contained mainly n‐hexacosane, n‐tricosane and n‐heneicosane. The oils and hexane extracts of S. spicigera and T. fallax exhibited potent antibacterial activity over a broad spectrum against 25 phytopathogenic bacterial strains. Carvacrol and thymol, the major constituents of S. spicigera and T. fallax oils, also showed potent antibacterial effect against the bacteria tested. The oils of Achillea species showed weak antibacterial activity. Our results also revealed that the essential oil of S. spicigera, thymol and carvacrol could be used as potential disinfection agents against seed‐borne bacteria. CONCLUSION: Our results demonstrate that S. spicigera, T. fallax oils, carvacrol and thymol could become potentials for controlling certain important agricultural plant pathogenic bacteria and seed disinfectant. Copyright © 2009 Society of Chemical Industry     

A Novel Preconcentration Procedure Using Neutral Red as Ion-Pairing Reagent for Determination of Inorganic Dissolved Arsenic Species in Different Water and Beverages by Spectrophotometry

In the current study, a new cloud point extraction (CPE) procedure was developed for the separation and preconcentration of inorganic soluble As species, As(III), As(V), and total As in water and beverage samples. Selective ion-pairing complex of As(III) with Neutral red (NRH⁺) being a cationic phenazine-based dye in presence of citric acid at pH 2.0 was extracted into the surfactant-rich phase of octylphenoxypolyethoxyethanol (Triton X-114) from samples. After phase separation, the preconcentrated As(III) was determined by means of spectrophotometer at 542 nm. After optimization of the CPE conditions, a preconcentration factor of 50 and the detection and quantification limits of 1.44 and 4.8 μg L^?1 with a correlation coefficient of 0.9953 were obtained from the calibration curve constructed in the range of 5–1500 μg L^?1 for As(III). The precision of the method (as RSD) was in the range of 2.2–4.5 % (25, 100, and 750 μg L^?1, N?=?5). The As(V) contents of samples were calculated from the difference between As(III) and total As contents after the reduction of As(V) to As(III) with mixture of KI and ascorbic acid at HCl media. The method is very versatile and inexpensive because it exclusively used conventional UV–Vis spectrophotometry. The method was succesfully applied to the simultenous determination of inorganic arsenic species in different water and beverage samples. Its accuracy and precision were controlled by analysis of two certified reference materials (CRMs).

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Graphical Abstract Experimental steps of the CPE procedure for detection of As(III), As(V), and total As in beverage samples.

     

Process intensification for heavy oil upgrading using supercritical water

Demand for light hydrocarbons has been steadily increasing in the market with a corresponding decrease in heavy hydrocarbon demand. Therefore, there is a need to develop environmentally friendly and efficient technologies for conversion of heavy molecular weight hydrocarbons. Supercritical fluids (SCF) are attracting increased attention as solvents for green chemistry and among those supercritical water (SCH₂O) is promising for the upgrading of heavy hydrocarbons. Because of a sharp decrease in its dielectric constant, water loses its polarity when brought to the supercritical conditions and its properties starts to resemble the properties of hydrocarbons and becomes an excellent solvent for organic compounds. Moreover, increased ionic product of water leads to an increasing [H₃O⁺] concentration and thus promotes the reactions requiring the addition of an acid. Solvation power enables the extraction of lighter compounds while increased [H₃O⁺] concentration makes the reactive extractions of heavy hydrocarbons possible. As a result of its favorable properties, a wide variety of process intensification studies have been carried out using near critical or SCH₂O such as combined distillation-cracking-fractionation and in some cases even without the utilization of catalysts and/or hydrogen. In this review, recent advances on reactions of hydrocarbons occurring in a SCH₂O environment will be highlighted. Fundamental aspects of these reactions including their thermodynamics and kinetics will be discussed. Experimental and theoretical developments on phase equilibria of relevant water–hydrocarbons systems will be presented.     

A successive parameter estimation algorithm for chirplet signal decomposition

In ultrasonic imaging systems, the patterns of detected echoes correspond to the shape, size, and orientation of the reflectors and the physical properties of the propagation path. However, these echoes often are overlapped due to closely spaced reflectors and/or microstructure scattering. The decomposition of these echoes is a major and challenging problem. Therefore, signal modeling and parameter estimation of the nonstationary ultrasonic echoes is critical for image analysis, target detection, and object recognition. In this paper, a successive parameter estimation algorithm based on the chirplet transform is presented. The chirplet transform is used not only as a means for time-frequency representation, but also to estimate the echo parameters, including the amplitude, time-of-arrival, center frequency, bandwidth, phase, and chirp rate. Furthermore, noise performance analysis using the Cramer Rao lower bounds demonstrates that the parameter estimator based on the chirplet transform is a minimum variance and unbiased estimator for signal-to-noise ratio (SNR) as low as 2.5 dB. To demonstrate the superior time-frequency and parameter estimation performance of the chirplet decomposition, ultrasonic flaw echoes embedded in grain scattering, and multiple interfering chirplets emitted by a large, brown bat have been analyzed. It has been shown that the chirplet signal decomposition algorithm performs robustly, yields accurate echo estimation, and results in SNR enhancements. Numerical and analytical results show that the algorithm is efficient and successful in high-fidelity signal representation.     

Concentration Dependence of Moisture Diffusivity in Aluminum Particle Filled Epoxy Adhesive in Salt Solutions

Moisture and aggressive ion ingress into bonded joints are primary causes of adhesive degradation. In this study, moisture diffusion behavior of aluminum-powder-filled epoxy adhesive was investigated through utilizing fluid immersion tests under complete immersion in salt solutions with varying NaCl concentrations. Aluminum powder is used in the adhesive for the purpose of improvement of its thermal properties, as demanded in a variety of industrial applications. Mass diffusivity for each specimen was determined by two methods, one using the diffusion data at early times (away from the saturation point) and the other using the data at large times (close to the saturation point). The results of the two methods were quite different, indicating that diffusivity is concentration dependent and a constant diffusivity assumption might lead to error in determining moisture diffusivity values in epoxy systems. Qualitatively, however, both methods indicated similar diffusion behavior. According to the results of both methods, the aluminum filler content did not affect the moisture diffusivity in the epoxy adhesive significantly but the effect of salt concentration was significant; the higher the salt content in the test solution, the higher the moisture diffusivity in the adhesive.     

Thermal conductivity of limestone from Gaziantep (Turkey)

In this study, thermal conductivity (TC) of limestone from Gaziantep, Turkey, was investigated. The limestone samples were collected from different parts of the city representing Gaziantep and F?rat formation which are clay and chalky limestone. TC of the samples was measured for saturated, partially saturated and dried conditions. Water absorption, dry unit weight and apparent porosity of the samples were also measured to correlate with TC. Measurements showed that TC was increased with increasing the water content of samples. The TC of the samples decreased while the porosity increased. Relationships between TC and both dry unit weight and porosity were driven. There was a very good exponential relationship between TC and saturation degrees of sample, porosity and density. Moisture content increased TC up to 113%.     

Renal artery embolization in severe nephrotic syndrome

Introduction Severe nephrotic syndrome is associated with increased morbidity and mortality. Renal artery embolization (RAE) has been used in a number of renal diseases such as renal tumors, arteriovenous fistulas etc. However, data regarding benefits of RAE in patients with symptomatic severe proteinuria is limited. We decided to evaluate role of RAE in the setting of severe symptomatic nephrotic syndrome. Methods Eight patients who had undergone transcatheter renal artery embolization with polyvinyl alcohol (PVA) were included. Clinico‐demographic characteristics as well as baseline laboratory data including level of proteinuria, serum albumin, C‐reactive protein and LDL cholesterol levels were recorded for each patient. After RAE, outpatient clinic control laboratory values were also assessed. Findings All patients except one underwent bilateral RAE (four simultaneous or three sequential). Two patients experienced postembolization syndrome characterized by flank pain, fever, and leukocytosis, which was self‐limited and responded to analgesics in all patients. There was no technical complications associated with RAE procedure. All patients became anuric except one. Serum albumin levels increased and serum LDL‐cholesterol levels decreased considerably in treated patients. Discussion Renal artery embolization with the purpose of amelioration in nephrotic syndrome complications was effective and free of major technical complications in our patients.     

Malicious code detection in android: the role of sequence characteristics and disassembling methods

The acceptance and widespread use of the Android operating system drew the attention of both legitimate developers and malware authors, which resulted in a significant number of benign and malicious applications available on various online markets. Since the signature-based methods fall short for detecting malicious software effectively considering the vast number of applications, machine learning techniques in this field have also become widespread. In this context, stating the acquired accuracy values in the contingency tables in malware detection studies has become a popular and efficient method and enabled researchers to evaluate their methodologies comparatively. In this study, we wanted to investigate and emphasize the factors that may affect the accuracy values of the models managed by researchers, particularly the disassembly method and the input data characteristics. Firstly, we developed a model that tackles the malware detection problem from a Natural Language Processing (NLP) perspective using Long Short-Term Memory (LSTM). Then, we experimented with different base units (instruction, basic block, method, and class) and representations of source code obtained from three commonly used disassembling tools (JEB, IDA, and Apktool) and examined the results. Our findings exhibit that the disassembly method and different input representations affect the model results. More specifically, the datasets collected by the Apktool achieved better results compared to the other two disassemblers.

     

Adaptive backstepping sliding mode control with tuning functions for nonlinear uncertain systems

An adaptive backstepping tuning functions sliding mode controller is proposed for a class of strict-feedback nonlinear uncertain systems. In this control design, adaptive backstepping is used to deal with unknown or uncertain parameters and the matching condition restricting the Lyapunov based design. The main drawback of the Lyapunov based adaptive backstepping which is the overparametrisation is eliminated by the tuning functions. The adaptive backstepping tuning functions design is combined with the sliding mode control in order to overcome quickly varying parametric and unstructured uncertainties, and to obtain chattering free control. The proposed controller not only provides robustness property against uncertainty but also copes with the overparametrisation problem. Experimental results of the proposed controller are compared with those of the standard sliding mode controller. The proposed controller exhibits satisfactory transient performance, good estimates of the uncertain parameters, and less chattering.     

The effect of computer-assisted teaching on remedying misconceptions: The case of the subject “probability”

The aim of this study is to determine the effects of computer-assisted teaching (CAT) on remedying misconceptions students often have regarding some probability concepts in mathematics. Toward this aim, computer-assisted teaching materials were developed and used in the process of teaching. Within the true-experimental research method, a pre- and post-test control group study was carried out with 37 seventh-grade students-18 in the experimental group (CAT) and 19 in the control group (traditional teaching). A 12-item instrument, made up of 4 items related to each of the concepts “Probability Comparisons (PC),” “Equiprobability (E),” and “Representativeness (R),” was developed and implemented with the participants. After the teaching intervention, the same instrument was again administered to both groups as a post-test. In light of the findings, it can be concluded that computer-assisted teaching was significantly more effective than traditional methods in terms of remedying students’ misconceptions.