CoopStor: a cooperative reliable and efficient data collection protocol in fault and delay tolerant wireless networks

Wireless Networks - Internet of things consist in the deployment of constrained and battery-powered devices with a radio interface. Most industrial applications require to respect strict...     

Modification of Niven's medium for the enumeration of histamine-forming bacteria and discussion of the parameters associated with its use

The objective of this study was to improve Niven's medium (NM) for the optimized enumeration of histamine-forming bacteria (HFB). The parameters modified related to solidification of the agar at low pH values (pH 5.3 to 5.8), incubation time (24, 48, and 72 h) and temperature (30 and 37 degrees C), number of colonies developed on the plate to allow enumeration of HFB, and color differentiation. Strains of HFB, Morganella morganii, Klebsiella pneumoniae, and Hafnia alvei were examined for their ability to change color on NM. The three microorganisms produced different colors on the medium, which can be used for preliminary identification of HFB. Quantitative analysis of HFB proved to be achievable, with the prerequisite that only 1 to 80 colonies developed on the medium allow effective enumeration. A larger number of colonies results in color development throughout the medium, making the distinction between HFB and other bacteria unachievable. Growth of prolific HFB was noticeably better at pH values from 5.3 to 5.5, compared to 6.3, on NM. Growth at 5.3 and 5.5 on NM also presented a significant advantage in comparison to growth on plate count agar (PCA; pH 7) at the same incubation temperature. The increased agar concentration of 3% was found to give better solidification at pH 5.3 to 6.0, compared to 2%. This agar concentration also allows autoclaving for 12 min at 121 degrees C, overcoming the hydrolysis problems that appear at the lower concentration of 2%. The construction of a color chart for the recognition of the pH change due to histidine decarboxylase activity was also achieved.     

Physicochemical and sensory analysis of dry bean landraces in conjunction with multivariate analysis: an exploratory approach

Five landraces of Greek common dry bean (Phaseolus vulgaris L.), were analysed for thirteen physico‐chemical and eighteen sensory variables. Brightness, acceptance, odour and hardness were the most important sensory variables for the overall acceptability of the cooked product. Application of principal component analysis revealed a rather weak relationship between the sensory attributes and the physico‐chemical variables. However, a certain grouping of cultivars with corresponding properties [(PC1 vs. PC2, Kastoria with saltiness, hardness, grassiness, intensity, protein and metal; Byzitsa bushy with fat, odour and sourness; Ksanthi and Belestino with tenaciousness, chroma, pH and overall impression), (PC1 vs. PC3 Byzitsa bushy with odour and acridness; Ksanthi with metal, hardness and pH; Kastoria with colour, protein and intensity)] was made. On the contrary, cluster analysis showed a much more satisfactory grouping of dry bean varieties based on their geographical origin. The multiple regression equation explained 72.3% of the variation in total acceptance of dry beans. The relative importance of brightness, acceptance, smell and hardness in predicting the overall impression of dry beans was 13%, 13.7%, 26% and 10%, respectively. These results may indicate that smell, brightness and acceptance are the most important factors determining dry bean total acceptability, so effort should be directed at improving these attributes in an attempt to satisfy consumer experience.     

Cold adaptation of a psychrophilic chitinase: a mutagenesis study

The gene encoding chitinase ArChiB from the Antarctic Arthrobactersp. TAD20 has been expressed in Escherichia coli and the recombinantenzyme purified to homogeneity. In an effort to engineer cold-adaptedbiocatalysts through rational redesign to operate at elevatedtemperatures, we performed several mutations aiming to increasethe rigidity of the molecular edifice of the selected psychrophilicchitinase. The mutations were designed on the basis of a homology-basedthree-dimensional model of the enzyme, and included an attemptto introduce a salt bridge (mutant N198K) and replacements ofselected Gly residues by either Pro (mutants G93P, G254P) orGln (G406Q). Mutant N198K resulted in a more stable protein(     

Banana cultivars, cultivation practices, and physicochemical properties

The physicochemical (pH, texture, Vitamin C, ash, fat, minerals) and sensory properties of banana were correlated with the genotype and growing conditions. Minerals in particular were shown to discriminate banana cultivars of different geographical origin quite accurately. Another issue relates to the beneficial properties of bananas both in terms of the high dietary fiber and antioxidant compounds, the latter being abundant in the peel. Therefore, banana can be further exploited for extracting several important components such as starch, and antioxidant compounds which can find industrial and pharmaceutical applications. Finally, the various storage methodologies were presented with an emphasis on Modified Atmosphere Packaging which appears to be one of the most promising of technologies.     

Impact of the ambient temperature rise on the energy consumption for heating and cooling in residential buildings of Greece

Annual values of heating and cooling degree-days for two typical base temperatures, namely 15 °C for heating and 24 °C for cooling, and for the two main cities of Greece (Athens and Thessaloniki) from 1983 to 2002 are presented in the study, calculated using hourly dry bulb temperature records from the meteorological stations of the National Observatory of Athens and of the Aristotle University of Thessaloniki. The decade average (1983–1992 and 1993–2002) values of the heating and cooling degree-days of the two cities are compared, for various base temperatures. The results show that the average value of heating degree-days of Athens for the decade 1993–2002, depending on the base temperature, is reduced from 8% to 22% as compared to the corresponding value of the decade 1983–1992. Similarly, the reduction in the Thessaloniki case is found in the range 4.5%–9.5%. The difference in the average value of cooling degree-days of the decades is more pronounced, the increase ranging from 25% to 69% for Athens and from 10% to 21% for Thessaloniki. In order to evaluate the effect of these changes on the energy requirements for heating and cooling of a typical residential building, the latter were calculated using the variable base degree-day method and the data sets of the two decades. The results show a reduction of the heating energy demand by 11.5% and 5% and an increase of the cooling energy demand by 26% and 10%, for Athens and Thessaloniki respectively.     

Wine waste treatment methodology

As more than 20% of wine production is waste, the latter constitutes a serious environmental problem that has to be solved urgently. Several methodologies such as composting, aerobic and anaerobic digestion, thermophilic anaerobic digestion, electrodialysis, pyrolysis, ozonation and wet oxidation among others were launched in an effort to solve effectively the wine waste management. This review aims at presenting comparatively and critically the characteristics of the currently employed waste treatment methods (properties, advantages and disadvantages, effectiveness) in order to emerge (with the aid of numerous tables and figures) the most promising and effective method.     

Potato: a comparative study of the effect of cultivars and cultivation conditions and genetic modification on the physico-chemical properties of potato tubers in conjunction with multivariate analysis towards authenticity

Potato (Solanum tuberosum L.) is a highly nutritious, mild flavored, easy to blend food that has many possibilities for "building in" desired nutrients. Varietal and environmental differences are known to exist in the shape, size, and nutritional content of potatoes. Different populations opt for varying sensory properties in relation to their diets. Potatoes are a low energy food in comparison to cereals and legumes. The aim of this review was to present an update of the currently conducted studies both on the characterization of several potato varieties (physical, chemical, and sensory analysis) and by means of genetic modification. Towards this target, five comprehensive tables were compiled where all recent data (physicochemical properties) and GM varieties were presented in conjunction with multivariate analysis (chemometrics). The latter was shown to be effectively used towards authenticity purposes (identification of geographical origin, variety, GM).     

A Broadband Monitoring System for Electromagnetic-Radiation Assessment

A broadband monitoring system for measuring the total electric field radiated from broadcasting (radio, TV) and communications (mobile telephony, TETRA, WLAN) systems is presented. The system has been implemented for recording the field on a 24-hour basis. It has an omnidirectional sensor antenna and the appropriate electronic circuits. The heart of the system is a low-power, eight-bit RISC Microchip microcontroller, running at 10 MHz. Various digital and analog peripherals are connected to the microcontroller. The system can send the data to a personal computer through a USB interface, and can communicate through a GSM modem. Low cost and high reliability render the system inexpensive for the deployment of electromagnetic radiation-monitoring networks, and make it trustworthy for the public. Several tests of the sensor's pattern, the linearity of the response, and the frequency response have shown that the system can be successfully compared with commercially available systems.