Impact of Different Storage Regimes on the Levels of Physicochemical Characteristics,Especially Free Acidity in Talh (Acacia gerrardii Benth.) Honey

This study investigates how storage conditions (temperature and duration) may affect the physicochemical parameters, especially free acidity (FA), of Talh honey originating from Acacia gerrardii that have naturally high FA levels. Fresh Talh honey samples were kept at 0, 25, 35, and 45 °C, and analyzed monthly over a period of eight months. The Talh honey was monofloral with 69% A. gerrardii pollen content. The free acidity (FA) of freshly harvested Talh honey samples was higher (93 ± 0.3 meq/kg) than that of standard limits (≤50 meq/kg) and remained stable at 0 °C throughout the storage period. A significantly increase in FA started to occur after storage for 6 months at 25 °C (103 ± 0.2 meq/kg), 2 months at 35 °C (108 ± 0.3 meq/kg), and 1 month at 45 °C (112 ± 0.3 meq/kg). After 8 months of storage, the highest FA level was recorded at 45 °C (159 ± 0.5 meq/kg), followed by 127 ± 0.3 meq/kg at 35 °C, 105 ± 0.2 meq/kg at 25 °C, and 94 ± 0.3 meq/kg at 0 °C. It was found that 0 °C was an appropriate temperature for storing honey for long time. The electrical conductivity (EC) of fresh Talh samples (1.46 ± 0.0 mS/cm) was above the accepted limit (≤0.8 mS/cm), which was slightly increased (non-significant) throughout the storage period under all the storage temperatures. Hydroxymethylfurfural (HMF), diastase activity (DN), and reducing sugars (RSs) showed normal levels only at 0 °C and 25 °C throughout the storage period. However, HMF exceeded the standard limits after the first month at 45 °C (127 ± 9.6 mg/kg) and after the second month at 35 °C (90 ± 23.5 mg/kg), DA decreased below standard limits after the second month (5 ± 1 DN) under 45 °C and after the seventh month under 35 °C (7 ± 2 DN, and RSs decreased below 60% after 2 months under 45 °C and after 6 months at 35 °C. The physicochemical parameters (moisture content, pH, color, and sucrose) were the least affected and were within the standard range throughout the storage period under all the storage temperatures. The levels of FA and EC in fresh Talh samples were higher than the acceptable limits. The moisture content, pH, color, and sucrose content were not affected by storage conditions and remained within the acceptable limits. HMF, DA, and RSs were significantly affected by storage conditions only at 35 and 45 °C. The storage of honey at low temperatures (0 and 25 °C) for up to eight months presented the least amount of changes in the honey, and the honey was unchanged from its fresh status. Honey storage at 35 and 45 °C resulted in significant changes. It is recommended that Talh honey, which normally has high acidity levels, should be stored at temperatures not exceeding 25 °C.     

Design study and heat transfer analysis of a neutron converter target for medical radioisotope production

A worldwide challenge in the near future will be to find a way of producing radioisotopes in sufficient quantity without relying on research reactors. The motivation for this innovative work on targets lies in the accelerator-based production of radioisotopes using a neutron converter target as in the transmutation by adiabatic resonance crossing concept. Thermal analysis of a multi-channel helium cooled device is performed with the computational fluid dynamics code CFX. Different boundary conditions are taken into account in the simulation process and many important parameters such as maximum allowable solid target temperature as well as uniform inlet velocity and outlet pressure changes in the channels are investigated. The results confirm that the cooling configuration works well; hence such a solid target could be operated safely and may be considered for a prototype target.     

Estimating satisfiability

The problem of estimating the proportion of satisfiable instances of a given CSP (constraint satisfaction problem) can be tackled through weighting. It consists in putting onto each solution a non-negative real value based on its neighborhood in a way that the total weight is at least 1 for each satisfiable instance. We define in this paper a general weighting scheme for the estimation of satisfiability of general CSPs. First we give some sufficient conditions for a weighting system to be correct. Then we show that this scheme allows for an improvement on the upper bound on the existence of non-trivial cores in 3-SAT obtained by Maneva and Sinclair (2008) [17] to 4.419. Another more common way of estimating satisfiability is ordering. This consists in putting a total order on the domain, which induces an orientation between neighboring solutions in a way that prevents circuits from appearing, and then counting only minimal elements. We compare ordering and weighting under various conditions.     

Chemoproteomic Discovery of AADACL1 as a Regulator of Human Platelet Activation

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Identification of wild collected mosquito vectors of diseases using gas chromatography–mass spectrometry in Jazan Province,Saudi Arabia

Thirty‐three species of mosquitoes have been reported from the Kingdom of Saudi Arabia. Several of these mosquitoes, Anopheles gambiae Giles s.l., Anopheles stephensi Liston, Culex pipiens Linnaeus, Culex quinquefasciatus Say, Culex tritaeniorhynchus Giles, Stegomyia aegypti (Linnaeus) and Aedimorphus vexans arabiensis (Patton) are known vectors of human and animal diseases. In this study, the cuticular hydrocarbon profiles of eight mosquito species using gas chromatography–mass spectrometry were analyzed. Wild collected fourth‐instar larvae were reared, and single, newly emerged, unfed adult females were used for the analysis. A total of 146–160 peaks were detected from the cuticular extracts by gas chromatography. Repeated analysis of variance (ANOVA) and Tukey HSD Post Hoc test was used to test for quantitative differences in relative hydrocarbon quantity. In addition, a linear regression model was applied using Enter method to determine the diagnostic peaks for the eight mosquito specimens. The ANOVA test indicated that relative peaks were significant (P < 0.05) when selected pairs of peaks were compared. Also, seven compounds showed qualitative differences among the five mosquito vectors tested. The classes of constituents present were n‐alkanes, monomethylalkanes, dimethylalkanes, trimethylalkanes, alkenes, branched aromatic hydrocarbons, aldehydes and esters. These compounds have a carbon chain length ranging from 8 to 18 carbons. The most abundant compound in all adult mosquito specimens was n‐hexylacrylate [retention time (RT) 6.73 min], which was not detected in Cx. pipiens. In Cx. pipiens, the most abundant peak was benzaldehyde (RT 2.98 min). Gas chromatography–mass spectrometry is a suitable method to identify adult mosquitoes, especially from focal areas of public health concern such as Jazan Province, Saudi Arabia. This method allows a wide range of adult collected material to be identified with high accuracy. Copyright © 2013 John Wiley & Sons, Ltd.     

Covalently Immobilized Battacin Lipopeptide Gels with Activity against Bacterial Biofilms

Novel antibiotic treatments are in increasing demand to tackle life-threatening infections from bacterial pathogens. In this study, we report the use of a potent battacin lipopeptide as an antimicrobial gel to inhibit planktonic and mature biofilms of S. aureus and P. aeruginosa. The antimicrobial gels were made by covalently linking the N-terminal cysteine containing lipopeptide (GZ3.163) onto the polyethylene glycol polymer matrix and initiating gelation using thiol-ene click chemistry. The gels were prepared both in methanol and in water and were characterised using rheology, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Antibacterial and antibiofilm analyses revealed that the gels prepared in methanol have better antibacterial and antibiofilm activity. Additionally, a minimum peptide content of 0.5 wt% (relative to polymer content) is required to successfully inhibit the planktonic bacterial growth and disperse mature biofilms of P. aeruginosa and S. aureus. The antibacterial activity of these lipopeptide gels is mediated by a contact kill mechanism of action. The gels are non-haemolytic against mouse red blood cells and are non-cytotoxic against human dermal fibroblasts. Findings from this study show that battacin lipopeptide gels have the potential to be developed as novel topical antibacterial agents to combat skin infections, particularly caused by S. aureus.     

Preparation and Evaluation of Long Chain Alkyl Methacrylate Monoliths for Capillary Chromatography

This work describes the fabrication of long chain alkyl methacrylate monolithic materials for use as stationary phases in capillary liquid chromatography. After capillary inner wall surface activation with 3-(trimethoxysilyl)propyl methacrylate, monoliths were formed by copolymerization of either lauryl or stearyl methacrylate (LMA or SMA) with ethylene dimethacrylate (EDMA) as crosslinker, in the presence of azobisisobutyronitrile (AIBN) as initiator and a mixture of porogenic solvents including water, 1-propanol and 1,4-butanediol. The composition of the polymerization mixture was changed in terms of monomer, crosslinker and porogen ratio composition, in order to compare the influence of these parameters. The monoliths were prepared in 320 ??m i.d. and 200 mm length capillaries. The column morphology was characterized by optical microscopy and scanning electron microscopy (SEM). Total porosity and permeability of each column were calculated using uracil as unretained material by measuring the pressure drop across the columns as a function of linear velocity. The microglobule average size for each column was also determined using Hagen?CPoiseuille equation and compared with the SEM images. As expected, a decrease of the porogen to monomer ratio corresponded to smaller microglobules and a lower total porosity. The columns were then chromatographically evaluated; good results were obtained when these capillaries were used to separate mixtures of phenols, aromatics and drug compounds.     

Path Following for a Target Point Attached to a Unicycle Type Vehicle

In this article, we address the control problem of unicycle path following, using a rigidly attached target point. The initial path following problem has been transformed into a reference trajectory following problem, using saturated control laws and a geometric characterization hypothesis, which links the curvature of the path to be followed with the target point. The proposed controller allows global stabilization without restrictions on initial conditions. The effectiveness of this controller is illustrated through simulations.     

Origin of the slow linear viscoelastic response of aqueous foams

We have studied the slow linear viscoelastic response of wet aqueous foams by macroscopic creep compliance measurements, combined to a diffusing-wave spectroscopy investigation of the local dynamics. The data strongly suggest that this rheological response arises from two distinct relaxation mechanisms: The first is due to the coarsening induced bubble rearrangements and governs the steady-state creep; the second results from the interplay between surface tension and surface viscosity of the gas-liquid interfaces and gives rise to a transient relaxation.