Evaluation of Pseudomonas spp. through O2 and CO2 headspace analysis

This article proposes an approach to determine the level of Pseudomonas spp. in milk, based on the evaluation of the content of oxygen and carbon dioxide produced in the headspace of sealed vials; the research was divided into two phases: model building and preliminary validation. Three different strains of Pseudomonas spp., Ps. putida (wild strain) and Ps. fluorescens (wild and collection isolates), were used as targets. Data of CO₂ and O₂ were modelled through a modified positive (CO₂) or a negative Gompertz equation (O₂) to estimate the Minimum Detection Time (MDT), defined as the time to attain 3% of CO₂ (MDT₁) or a decrease in the content of O₂ by 3% (MDT₂). Then, MDT₁ and MDT₂ were submitted to a linear regression procedure, using cell concentration as independent variable; the correlations ‘MDT₁/cell concentration’ and ‘MDT₂/cell concentration’ showed high determination coefficients (>0.983). Moreover, the regression procedure pointed out that both MDT₁ and MDT₂ decreased by ca. 3 h for an increase in cell count of 1 log cfu mL^?1. Preliminary validation in milk pointed out that the error associated with the regression line ‘MDT₂/cell concentration’ was below 5%.     

Mercury,selenium, PCBs and fatty acids in fresh and canned fish available on the Slovenian market

In order to contribute to the general understanding of the risks and benefits of consuming fish and fish products, total mercury (THg), monomethylmercury (MeHg), polychlorinated biphenyls (PCBs), selenium (Se), n-3 and n-6 fatty acids were determined in fresh and canned fish on the Slovenian market. Furthermore, the mercury exposure of pregnant women in Slovenia was assessed by determining total mercury (THg) in hair, and through fresh and canned fish consumption obtained by a food frequency questionnaire. Based on the frequency of fish consumption and levels of MeHg, THg and PCBs determined in the present study, it can be concluded that fish available on the Slovenian market do not represent a health risk. It was also confirmed that fish are important sources of selenium and n-3 fatty acids.     

Sol gel transitions during acid gelation of milk containing modified waxy maize starch. Differences between chemical and bacterial acidification measured using rheological and spectroscopic techniques

Modified waxy maize starch (1%, w/v) was added to skim milk and the mixtures were heated and homogenized. Acidification was conducted at 40 °C, using either glucono-δ-lactone (GDL) or a commercial starter culture. The physico-chemical changes occurring during acidification were monitored using small oscillatory rheology, diffusing wave spectroscopy and ultrasound spectroscopy. A similar gelling behaviour was noted for GDL and bacterial-induced gels; however, a difference was noted in the values of storage modulus (G′). The presence of starch did not seem to affect the development of the gel structure, nor the mobility and positional correlations of the casein micelles during acidification. On the other hand, starch increased the final storage modulus, G′ of the acid milk gels. These results indicate the absence of direct interactions between micelles and the modified starch granules.     

The Perceived Authenticity of Iconic Heritage Sites in Urban Tourism: the Case of Constitutional Hill,Johannesburg, South Africa

Cultural heritage sites play multiple roles in the development of urban tourism. Amongst these roles, the authentic properties of cultural heritage generate a sense of place, are the main source of authentic tourist experience and assume an important role in reaffirming cultural and national identity. This paper provides a contribution to authenticity discourse both theoretically and empirically. The study examines and re-evaluates the main sources of authenticity of tourist experience generated from South African iconic places which serve a dual function, as ‘must-see’ tourist attractions and as places of new post-1994 national African identity building. The focus is the Constitution Hill heritage site in Johannesburg. The research explores how authentic is the individual tourist experience of the site and whether differences exist in the way domestic and international tourists perceive the authenticity of the iconic place as representative of new South African identity. The results show that the majority of tourists perceive the place as authentic and derive an authentic experience from the visit. No statistically significant differences are observed between the experience of domestic versus international tourists’ experience of the site which was measured by four variables of authentic experience, namely, attraction, attention, outcomes and feelings.     

Theoretical and Experimental Analysis of Moisture-Dependent Thermal Conductivity of Lightweight Ceramic Bricks

The moisture-dependent thermal conductivity of two types of lightweight ceramic brick body is analyzed using both theoretical and experimental approaches. The basic physical properties are determined at first. Then, an impulse method is applied for the thermal-conductivity measurement. Initially, the material samples are dried, after that, they are exposed to liquid water for specific time intervals, and finally the moisture content is allowed to homogenize within the whole volume. The thermal-conductivity measurement is performed for different moisture contents achieved in this way. In the theoretical part, the homogenization principles are used for the calculation of the moisture-dependent thermal conductivity, utilizing the distribution functions based on the pore-size distribution measurement. Finally, a comparison of the measured and calculated data is done, and the validity of the applied effective media treatment is assessed.     

Aluminum scandium nitride thin-film bulk acoustic resonators for wide band applications

Piezoelectric c-textured Al_(1−x)Sc_xN thin films, where the Sc relative concentration, x, varies in the range 0-0.15 have been studied in view of radio frequency (RF) electro-acoustic applications. Thin film bulk acoustic wave resonators (FBARs) employing these films were fabricated and characterized as a function of the Sc concentration for the first time. The measured electromechanical coupling is found to increase by as much as 100% in the above concentration range. The results from this work underline the potential of the c-textured Al_(1−x)Sc_xN based FBARs for wide band RF applications.     

Lipidation of Temporin-1CEb Derivatives as a Tool for Activity Improvement,Pros and Cons of the Approach

The alarming raise of multi-drug resistance among human microbial pathogens makes the development of novel therapeutics a priority task. In contrast to conventional antibiotics, antimicrobial peptides (AMPs), besides evoking a broad spectrum of activity against microorganisms, could offer additional benefits, such as the ability to neutralize toxins, modulate inflammatory response, eradicate bacterial and fungal biofilms or prevent their development. The latter properties are of special interest, as most antibiotics available on the market have limited ability to diffuse through rigid structures of biofilms. Lipidation of AMPs is considered as an effective approach for enhancement of their antimicrobial potential and in vivo stability; however, it could also have undesired impact on selectivity, solubility or the aggregation state of the modified peptides. In the present work, we describe the results of structural modifications of compounds designed based on cationic antimicrobial peptides DK5 and CAR-PEG-DK5, derivatized at their N-terminal part with fatty acids with different lengths of carbon chain. The proposed modifications substantially improved antimicrobial properties of the final compounds and their effectiveness in inhibition of biofilm development as well as eradication of pre-formed 24 h old biofilms of Candida albicans and Staphylococcus aureus. The most active compounds (C5-DK5, C12-DK5 and C12-CAR-PEG-DK5) were also potent against multi-drug resistant Staphylococcus aureus USA300 strain and clinical isolates of Pseudomonas aeruginosa. Both experimental and in silico methods revealed strong correlation between the length of fatty acid attached to the peptides and their final membranolytic properties, tendency to self-assemble and cytotoxicity.     

Selenium content of breast milk

Selenium levels in human milk in the winter period ranged from 5.3 μg/l to 23.8 μg/l, the mean value being 11.0 μg/l. The nursing women were divided into several groups according to the results of a questionnaire, i.e. according to their social status (refugees or otherwise), number of deliveries, post partum days, the weight they had gained during pregnancy, their age and smoking habits. The mean levels of selenium for each group are presented. Selenium was determined by hydride generation atomic absorption spectrometry.     

On properties of multicast routing trees

In the last several years we witnessed the proliferation of multimedia applications on the Internet. One of the unavoidable techniques to support this type of communication is multicasting. However, even a decade after its initial proposal, multicast is still not widely deployed. One of the reasons is the lack of a solid business model. If the gain and the cost of multicast could be predicted, network operators might be encouraged to deploy multicast on a larger scale. In this paper we propose analytical expressions that could be used to estimate the gain of network‐layer multicast. We show that the theoretical model matches extensive simulation and Internet measurement results remarkably well. Furthermore, we examine the reliability of traceroute data and of traceroutes‐based conclusions. We investigate the node degree distributions in the Internet maps obtained from CAIDA and RIPE and we show the divergency of our results with those obtained by other researchers. We further focus on the analysis of multicast trees based on traceroute data. Only few results have been available on the node degree distribution of multicast routing trees which provided contradictory conclusions. Our results seem to indicate that the node degrees follow power laws only for a large number of multicast users. Copyright © 2005 John Wiley & Sons, Ltd.     

Career-Sustaining Behaviors, Satisfactions, and Stresses of Professional Psychologists.

A random sample of licensed psychologists from Illinois (N=286) responded to a survey about career-sustaining behaviors (CSBs) and about satisfactions and stresses they experience at work. The highest rated CSBs were spending time with partner/family, maintaining a balance between personal and professional lives, and maintaining a sense of humor. Overall, more satisfied respondents reported greater importance of CSBs. Female respondents reported significantly greater use of CSBs than male respondents and were more likely to endorse behaviors that were relational or educational in nature, such as participating in personal therapy, spending time with friends, discussing work frustrations with colleagues, seeking case consultation, maintaining regular contact with referral networks, participating in continuing-education programs, reflecting on positive experiences, and engaging in quiet leisure activities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)