Sludge dewatering using the reed bed system in the Gaza Strip, Palestine

Sludge treatment using reed beds is more attractive in the Gaza Strip than traditional sludge drying beds. Sludges having solids contents of 1–2% can be applied to reed beds at a loading of 40 cm/m² every 2 weeks. The infiltration rate for a reed bed system is high, and the evapotranspiration rate is typically 170% of pan evaporation. The cost of sludge treatment using reed beds is 0.34 US$/m³ compared with 1.01 US$/m³ for treatment using conventional drying beds. This paper presents the results of using reed beds for sludge treatment in the Gaza Strip for 3 years.     

Non-productive tool path optimisation of multi-tool part programmes

The paper concerns the development of a computer-aided optimisation package for the minimisation of the residence time of a multi-component pallet being manufactured in a machining centre with a multi-tool facility. A methodology has been developed to take a part programme for the manufacture of many components which involves many tool changes, segment it, automatically re-sequence the machining order and regenerate it. Random input case studies have been used to demonstrate the ability of the software to minimise the number of tool changes and to find the near optimum tool path. A typical industrial case is given in the paper to show the ability of the software to reduce the residence time of a part programme. It is shown that the use of the computer-aided optimisation package with a range of part programmes reduced the pallet residence time by a factor between 4.6% and 32.3%.     

CMOL implementation of spiking neurons and spike‐timing dependent plasticity

Successful implementation of spiking neural networks onto CMOS‐Molecular (CMOL) architecture has already been proposed, but the ability of dynamic learning has not yet been addressed. Here, we propose a spiking neural topology with spike‐timing‐dependent learning ability and provide its basic building blocks that are easily mapped onto CMOL architecture. The learning method modifies state of synaptic switches, using spatially and temporally local information which is available at the synapse when state modification is performed. The performance of the proposed topology is analyzed with regards to pre‐ and post‐synaptic spike timing, and simulation results are provided for a synapse with spike‐timing‐dependent plasticity properties. Furthermore, its performance as spike‐timing correlation learning and synchrony detection in a small feed‐forward network is demonstrated as a case example. Copyright © 2010 John Wiley & Sons, Ltd.     

Stabilizing nanocrystalline Cu2O with ZnO/rGO: Engineered photoelectrodes enables efficient water splitting

The engineered photoelectrodes have received significant attention in the photoelectrochemical (PEC) applications. Herein, we prepared a highly effective photoelectrode based on Cu₂O decorated with ZnO and rGO for efficient PEC water splitting. Firstly, different thickness Cu₂O is sputtered on the FTO substrate (FC). The PEC performance of the FC photoelectrode further improved by depositing the ZnO and rGO protection layers (FCZG). The fabricated photoelectrodes are systematically investigated for their morphological and crystal structure by AFM, FESEM, TEM, XPS, XRD, and RAMAN, UVDRS, and PL analysis. The FCZG hybrid photoelectrode exhibit a photocurrent density of 4.94 mA cm^?2 at 0 V vs. reversible hydrogen electrode (RHE), which is 1.5 times higher than the unmodified photoelectrodes. The improved PEC performance of the FCZG hybrid photoelectrode is due to the high surface roughness, larger electrochemical active surface area, and less radiative recombination rate of the photogenerated charge carriers.     

Studying the anti-tyrosinase effect of Arbutus andrachne L. extracts

Arbutus andrachne L. is widely distributed in Jordan. Tyrosinase is the key enzyme in the biosynthesis of melanin. This preliminary study was carried out to assess the possible anti-tyrosinase activity of A. andrachne extracts. Arbutin, hydroquinone and kojic acid were selected as inhibitor standards. Five different extracts (chloroform, butanol, ethanol, methanol and water) were prepared from A. andrachne stems and their activities were compared with the selected tyrosinase inhibitors. IC₅₀ was measured for both, standard and plant extracts. Among the different extracts, the methanolic extract exhibited the highest anttyrosinase activity with an IC₅₀ value (1 mg mL⁻¹). Furthermore, 9 mg A. andrachne methanolic extract showed 97.49% inhibition of tyrosinase activity. Arbutin, hydroquinone, β-sitosterol and ursolic acid were identified in the different extracts of A. andrachne by thin layer chromatography (TLC) and isolated by preparative TLC from the methanolic and chloroform stem extracts, respectively.     

Estimation of probabilities using the logistic model in retrospective studies

Methods for estimating the parameters of the logistic regression model when the data are collected using a case-control (retrospective) scheme are compared. The regression coefficients are estimated by maximum likelihood methodology. This leaves the constant term parameter to be estimated. Four methods for estimating this parameter are proposed. The comparison of the four estimators is in two parts. First, they are compared for large samples. This is accomplished via the asymptotic distribution of the estimators. Second, the estimators are compared for small samples. This is conducted via stimulation using 11 logistic models. The estimation of the posterior probability of the response variable being a success (Px), as given by the logistic regression model, when the constant parameter is estimated by each of the four proposed methods is the main focus of this paper. A third concern is the comparison of the logistic discriminant procedures when each of the four methods of estimating the constant parameters is used. In addition, the linear discriminant function procedure is included. This comparison is executed only for small samples via simulation. It was found that when estimating Px, method 1 (which is essentially the MLE) minimizes the expected mean square error. The results were not as clear when the parameter of interest was the constant term itself. The results from the classification comparisons implied that when the logistic model contains mostly (or all) binary regression variables the logistic discriminant procedure using method 1 to estimate the constant term gives minimum expected error rate; otherwise the linear discriminant function gives minimum expected error rate. In the latter case the logistic discriminant procedure (method 1 estimator of the constant term) is approximately as good.     

Knowledge,attitude, and behavior of students regarding 'mad cow disease'

The aim of the current study is to assess the knowledge, attitude and behavior of students enrolled at the American University of Beirut (AUB) in Lebanon, towards mad cow disease (MCD). Three hundred and fifty-six students (199 males and 157 females), ranging in age between 17 and 25 years were randomly selected from various majors and were asked to fill out a self-administered questionnaire. It was found that 99.7% of students had heard about MCD and 85.8% knew that the cow is the host for bovine spongiform encephalopathy (BSE). Seventy five percent reported that animals contract the disease through the consumption of meat and bone meal. Thirty-seven percent wrongly believed that MCD cases were reported in Lebanon and 89% were not satisfied with the measures undertaken by the Lebanese government to curb the disease. Eighty four percent were concerned about the disease and 72% stated having modified their eating habits accordingly. Moreover, students majoring in biology and other health-related majors knew significantly more about MCD compared with students majoring in non-health related majors. A surprising finding was that females were more likely to modify their eating habits than males. Hence, this study provides an insight into the knowledge, attitude, and behavior of AUB students towards MCD. A limitation of this study is that our sample is not representative of all university students in Lebanon. Future surveys should also target students enrolled in other universities in the country.     

Development of Polyvinyl Alcohol/Kaolin Sponges Stimulated by Marjoram as Hemostatic,Antibacterial, and Antioxidant Dressings for Wound Healing Promotion

The predominant impediments to cutaneous wound regeneration are hemorrhage and bacterial infections that lead to extensive inflammation with lethal impact. We thus developed a series of composite sponges based on polyvinyl alcohol (PVA) inspired by marjoram essential oil and kaolin (PVA/marjoram/kaolin), adopting a freeze–thaw method to treat irregular wounds by thwarting lethal bleeding and microbial infections. Microstructure analyses manifested three-dimensional interconnected porous structures for PVA/marjoram/kaolin. Additionally, upon increasing marjoram and kaolin concentrations, the pore diameters of the sponges significantly increased, recording a maximum of 34 ± 5.8 µm for PVA-M0.5-K0.1. Moreover, the porosity and degradation properties of PVA/marjoram/kaolin sponges were markedly enhanced compared with the PVA sponge with high swelling capacity. Furthermore, the PVA/marjoram/kaolin sponges exerted exceptional antibacterial performance against Escherichia coli and Bacillus cereus, along with remarkable antioxidant properties. Moreover, PVA/marjoram/kaolin sponges demonstrated significant thrombogenicity, developing high thrombus mass and hemocompatibility, in addition to their remarkable safety toward fibroblast cells. Notably, this is the first study to our knowledge investigating the effectiveness of marjoram in a polymeric carrier for prospective functioning as a wound dressing. Collectively, the findings suggest the prospective usage of the PVA-M0.5-K0.1 sponge in wound healing for hemorrhage and bacterial infection control.     

Electrospinning of Continuous Aligning Yarns with a ‘Funnel’ Target

A new electrospinning set‐up is described for continuous aligning of poly(L ‐lactide) yarn. It comprises a slowly rotating grounded ‘funnel’ target and a winder placed right up to the funnel. A charged polymer jet is ejected from a nozzle. The electrospun fibers are first accumulated on the mouth plane of the funnel to form a web. The web is then pulled upward and guided to a winder on which twisted fibers are continuously wound as a bundle. Each filament of the bundle is slanted at about 45° relative to the collecting direction, and its average diameter is 6.0 ± 1.9 µm. The drawn fiber shows improved tensile properties as a result of the increased molecular orientation. The morphologies of the twisted fibers before and after drawing are compared.

     

Design of Star-Shaped Organoiron Oligomers with Azo Dye Bridges

A series of star-shaped macromolecules bearing distinct symmetrical branches with alternating organoiron complexes and azobenzene moieties were synthesized using both convergent and divergent approaches. The various azo dye and organoiron-containing branches were reacted with multifunctional cores via metal-mediated nucleophilic aromatic substitution and ester condensation reactions to afford multi-substituted three- and four-arm star-shaped oligomers. UV–vis spectral studies of complexes 15 and 22 (λ _max = 435 and 427 nm, respectively) show bathochromic shifts (λ _max = 576 and 558, respectively) at various HCl concentrations indicating their use as potential acid sensors. Cyclic voltammetric studies of the octa-iron oligomer 22 were reversibly reduced at E _1/2 = −1.53 V.