The Dicalcium Phosphate Dihydrate Fixator and Stabilizer of Glutaraldehyde

The dicalcium phosphate dihydrate （A） reacts with glutaraldehyde （B） in aqueous solution with a yield of 95%. The resulting product （C） is chemically stable. The obtained purity is checked by UV-Visible and the structure is discussed on the basis of the Infrared absorption FTIR. The reaction mechanism is explained by the approach of the hydroxyl group （-OH） of one of the aldehyde functions （-CO） of 1.5 dipentanal with the enolic form, which stabilizes the product （C）. The reversible reaction is performed by mild oxidation of the compound （C） in aqueous medium at ambient temperature. The compound （A） is generated with high efficiency. The comparative spectral and thermography study confirms this result.     

MMSMAC: A Multi-mode Medium Access Control Protocol for Wireless Sensor Networks with Latency and Energy-Awareness

In this paper, we propose a new medium access control (MAC) protocol for wireless sensor networks called MMSMAC (multi-mode sensor MAC protocol), which operates according to the application requirements and traffic load, in three main modes: synchronous, asynchronous, and hybrid. In the synchronous mode, MMSMAC organizes the sensor nodes under even and odd clusters. Each sensor node has its own active/sleep and send/receive periods according to its cluster identifier, which ensures better load balancing among nodes. In the asynchronous mode, sensor nodes communicate freely without the utilization of even and odd clusters. We propose a mechanism to wake up the destination node and minimize the overhead. In this mode, we propose another mechanism to circumvent the problem of hidden host. In the hybrid mode, the features of asynchronous and asynchronous modes are combined. Our simulation results and analysis show that each of the MMSMAC modes shows convincing performance gains and outperforms B-MAC and Hybrid CSMA/TDMA protocols.     

Optimal and suboptimal regional control of probabilistic cellular automata

Natural Computing - Probabilistic cellular automata are extended stochastic systems, widely used for modelling phenomena in many disciplines. The possibility of controlling their behaviour is...     

Assessment of the levels of chlorinated pesticides in breast milk in Kuwait

Breast milk samples, randomly collected from 32 Kuwaiti donors were analysed for chlorinated pesticides. DDE residues ranged from 127 to 3333 micrograms/kg, averaging, 833 micrograms/kg, expressed on a fat weight basis. DDT levels ranged from 0.6 to 67 micrograms/kg fat and averaged 12.4 micrograms/kg, fat. High DDE/DDT ratios were found, which indicated that the exposure to DDT, in most cases, happened quite some time ago. In addition many of the samples also contained isomers of HCH, heptachlor-epoxide, aldrin, dieldrin and endrin. Residue levels of non-DDT pesticides were generally low. Overall levels of DDT-pesticides in Kuwaiti milk samples were lower than levels reported from other Middle Eastern countries, although methodologies may not be directly comparable.     

Infrared study of the thermal behavior of γ-irradiated poly-(vinyl alcohol)

Infrared spectroscopy was applied for the investigation of the combined effects of γ-irradiation and heat on polyvinyl alcohol (PVA). The samples were exposed in an atmosphere of air at room temperature to doses ranging form 0.5 to 15 M rads. The obtained results revealed that exposure to γ-irradiation produces no considerable changes in the IR spectra of PVA apart from very slight changes in the intensities of the absorption bands. The crystallinity of the irradiated samples was determined by following the induced changes in the absorbances of the crystalline bands. The IR spectra of PVA samples heated at 180°C exhibited two absorption bands at 1580 and 1710 cm^?1 due to carbonyl groups. Alken double bonds and possibly also carboxyl groups. IR spectroscopy was also used for the examination of the effect of time of heating in air or in vacuum and also the effect of quenching of the degree of crystallinity of γ-irradiated PVA. Careful examination of the IR spectra led to the conclusion that the temperature induced changes depend on time of heating, rate of cooling and γ-dosage used. The highest crystallinity was obtained by heating in vacuum at 140°C and quenching at ?40°C.     

Low-index surface investigation of KAlH4: Theoretical attempt to study the surface effect on the hydrogen storage properties

Different preparations of complex hydrides lead to different hydrogen uptake and release. Besides, Potassium Aluminum hydride is a structure with different re/dehydrogenation properties than the rest of alanates. Given these considerations, we investigated nine stable cleavages on the (100), (010), (001), (111), and (101)KAlH₄ surfaces. The results reveal that, while the (010) surface energy is much higher, all the other surfaces are approximately in the same range of energy. Some of these surfaces would be placed on top of the nanocrystallites and the different decomposition pathways may be originated from the different characteristics of these surfaces, which is one of the central issues of the present study. Our results are in accordance with experimental data indicating that long hours milling of alanates just creates fresh surfaces and the structures remain unchanged. Due to the surface effect, huge changes in electronic and geometric characteristics occur. The band gaps are narrowed up to 2eV, which alongside with massive changes in chemical bonds, lead to an improved dehydrogenation relative to the bulk.     

Evaluating technological emergence using text analytics: two case technologies and three approaches

Scientometrics - Scientometric methods have long been used to identify technological trajectories, but we have seldom seen reproducible methods that allow for the identification of a technological...