Volatile organic compound profiles of yoghurt produced from cow's milk with different somatic cell counts

The present study aimed to investigate the effect of somatic cell count (SCC) of raw cow's milk on the volatile organic compound (VOC) profiles of yoghurt. Test yoghurt samples were produced from three batches of cow's milk with low, medium and high SCC, respectively. The VOCs were determined by gas chromatography–mass spectrometry (GC–MS) analysis. A lower diacetyl and acetoin content and a higher content of 2‐heptanone, and butanoic and hexanoic acids were established in the yoghurt samples from batches with high SCC of above 1 000 000 cells/cm³. The increased SCC of cow's milk had a negative effect on the volatile organic compound profiles of yoghurt.     

Trends in registered psychiatric morbidity and forecasting psychotropic drug needs in Bulgarian hospitals

Registered psychiatric morbidity in Bulgaria as a whole and particularly in Plovdiv, the second largest region of the country, was assessed. Three aspects of psychotropic drug usage were analysed, namely, changes in registered psychotropic drugs, the prescribed daily dose (PDD) values for 2 years, and the preferred therapeutic schemes, and drug usage and needs in a psychiatric hospital with 365 beds. This was done by time series analysis for evaluation of psychiatric morbidity and drug consumption data, calculation of PDD for psychotropic medicines, and, based on a modification of the World Health Organization's morbidity method, assessment and prediction of drug use and needs in Plovdiv hospital. The results indicated that the registered morbidity had increased by 4% over the period 1989-93 to 2,427 psychiatric patients per 100,000 people. The increased consumption of especially benzodiazepines and sedative medicines was analyzed. Diazepam was prescribed the most often (91.1%), followed by levomepromazine (86.4%), haloperidol (82.7%), etc. Future drug consumption in Plovdiv hospital is expected to decrease because therapeutic practice in hospitals has been revised and improved on the basis of the World Health Organization's recommendations.     

Electrophysiological properties and cholinergic responses of rat ventral oral pontine reticular neurons in vitro

This study analyses the relationship between the use of rotating instruments, the production of a smear layer and the presence of alterations to enamel microstructures. The rotating instruments used were carbide (8-12 blade) and diamond tipped (30-15 m) cutters. Cavities were made in extracted teeth. Subsequently, half the sample was analysed using the rugosimeter before and after the application of ortophosphoric acid at 35% for 15 and the other half suing a Scansion Electronic microscope (SEM). The results obtained showed on the one hand that carbide cutters leave a smoother surfacer than diamond tipped cutters, and on the other that the smear layer is eliminated better by carbide cutters compared to diamond tipped cutters. Moreover, there are no major traumatic-type alterations at the level of the enamel affecting the microstructure after the use of carbide cutters.     

Human-centered multimedia: culture, deployment, and access

Cultural setting is an intrinsic part of what we're trying to capture and use in muitimedia systems. However, being in our own culture (both everyday culture and professional culture) we forget that multimedia interfaces and communication are culture-specific. This article gives some great insights that stem from diversity in countries (and cultures) as well as inside the interdisciplinary multimedia community.     

High-power etched-facet lasers

We demonstrate, for the first time, laser diodes with anetched facet fabricated by chemically assisted ion beametching, producing 1?7 W pulsed and 470mW CW output power from one facet. The devices were coated and bonded junction-side-up and tested at room temperature. The single 40 ?m stripe, 300 ?m-long devices exhibit 94 mA threshold current and differential quantum efficiencies of 80% pulsed (78% CW).     

Using Multiple Solution Tasks for the Evaluation of Students’ Problem-Solving Performance in Geometry

Abstract

The article demonstrates that multiple solution tasks (MSTs) in the context of geometry can serve as a research instrument for evaluating geometry knowledge and creativity. Geometry knowledge is evaluated based on the correctness and connectedness of solutions, whereas creativity is evaluated based on a combination of fluency, flexibility, and originality of solutions. In this article, the MST research instrument is introduced in connection with the theoretical analysis of the research literature and then explained and analyzed using geometry students’ performance results on one MST. The analysis shows that the research instrument differentiates between students belonging to high- and regular-level instruction groups and sheds light on the interrelations between components of geometry knowledge and creativity.     

Micellization Behavior of Long-Chain Substituted Alkylguanidinium Surfactants

Surface activity and micelle formation of alkylguanidinium chlorides containing 10, 12, 14 and 16 carbon atoms in the hydrophobic tail were studied by combining conductivity and surface tension measurements with isothermal titration calorimetry. The purity of the resulting surfactants, their temperatures of Cr→LC and LC→I transitions, as well as their propensity of forming birefringent phases, were assessed based on the results of ¹H and ¹³C NMR, differential scanning calorimetry (DSC), and polarizing microscopy studies. Whenever possible, the resulting values of Krafft temperature (T_K), critical micelle concentration (CMC), minimum surface tension above the CMC, chloride counter-ion binding to the micelle, and the standard enthalpy of micelle formation per mole of surfactant (Δ_micH°) were compared to those characterizing alkyltrimethylammonium chlorides or bromides with the same tail lengths. The value of T_K ranged between 292 and 314 K and increased strongly with the increase in the chain length of the hydrophobic tail. Micellization was described as both entropy and enthalpy-driven. Based on the direct calorimetry measurements, the general trends in the CMC with the temperature, hydrophobic tail length, and NaCl addition were found to be similar to those of other types of cationic surfactants. The particularly exothermic character of micellization was ascribed to the hydrogen-binding capacity of the guanidinium head-group.     

Elimination kinetic model for organic chemicals in earthworms

Mechanistic understanding of bioaccumulation in different organisms and environments should take into account the influence of organism and chemical depending factors on the uptake and elimination kinetics of chemicals. Lipophilicity, metabolism, sorption (bioavailability) and biodegradation of chemicals are among the important factors that may significantly affect the bioaccumulation process in soil organisms. This study attempts to model elimination kinetics of organic chemicals in earthworms by accounting for the effects of both chemical and biological properties, including metabolism. The modeling approach that has been developed is based on the concept for simulating metabolism used in the BCF base-line model developed for predicting bioaccumulation in fish. Metabolism was explicitly accounted for by making use of the TIMES engine for simulation of metabolism and a set of principal transformations. Kinetic characteristics of transformations were estimated on the basis of observed kinetics data for the elimination of organic chemicals from earthworms.     

Conversion of Ethene to Propene by a Dual Function NiSO4/Re2O7/γ-Al2O3 Catalyst

A NiSO₄/Re₂O₇/γ-Al₂O₃ catalyst was prepared by co-impregnation using an aqueous solution of NiSO₄ and [NH₄][ReO₄], which catalyzes direct conversion of ethene to propene at mild reaction condition (323 K, 1 atm). Catalyst deactivation may be caused by coke formation. The two catalytic components appear to work independently of each other.