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391.
Attia M. Elfak Geoffrey Pass Glyn O. Phillips 《Journal of the science of food and agriculture》1979,30(7):724-730
The apparent viscosities of aqueous solutions of sodium carboxymethylcellulose (NaCMC) and k-carrageenan have been measured over a range of shear rates from 14 to 1142 s?1. Comparable measurements were also made on gum solutions to which glucose, sucrose, or glucose syrup had been added. For all the solutions the variation of relative viscosity with shear rate fits a power law equation. Addition of sugars to the most concentrated solutions of NaCMC has no effect on the non-Newtonian behaviour but addition of glucose syrup to the most dilute solutions of NaCMC decreased the non-Newtonian behaviour. However, the general pattern of behaviour showed close similarity with that of guar gum and locust bean gum. In the more concentrated glucose and sucrose solutions the non-Newtonian behaviour of k-carrageenan was increased appreciably. There was no comparable effect on k-carrageenan in glucose syrup solutions. This different behaviour of k-carrageenan is attributed to the development of solute-solute interactions. 相似文献
392.
This paper reports on silicon nanowire growth on oxidized silicon substrates using different approaches for gold catalyst
deposition. The gold coated surfaces and the resulting nanowires were characterized using scanning electron microscopy. The
gold catalysts were made up of gold nanoparticles (50 nm diameter), which were either dispersed or spotted at different concentrations
using a robot, or were formed on a patterned Si/SiO2 substrate by metal evaporation (63 nm diameter). The subsequent silicon nanowire growth was accomplished by CVD decomposition
of silane gas (SiH4) at high temperature (400–500°C) in a vapor-liquid-solid (VLS) process. Under these conditions, a high density of silicon nanowires (SiNWs) was achieved
on the oxidized silicon surfaces, but the distribution of the nanowires was found to be inhomogeneous in the case of the gold
nanoparticles. Such result is attributed to the aggregation of the nanoparticles during the growth process. Alternatively,
when gold nanodot catalysts were lithographically patterned on the surface, the nanowires were obtained in the patterned regions. 相似文献
393.
Ali S. Alqahtani Mostafa M. Ghorab Fahd A. Nasr Mohammad Z. Ahmed Abdullah A. Al Mishari Sabry M. Attia Muhammad Farooq Khan 《International journal of molecular sciences》2022,23(9)
Many quinazoline derivatives with pharmacological properties, such as anticancer activity, have been synthesized. Fourteen quinazoline derivatives bearing a substituted sulfonamide moiety (4a–n) were previously synthesized and fully characterized. These compounds exerted antiproliferative activity against cell lines derived from solid tumors. Herein, the antileukemic activities of these compounds (4a–n) against two different leukemia cell lines (Jurkat acute T cell and THP-1 acute monocytic) were investigated. Our investigation included examining their activity in vivo in a zebrafish embryo model. Remarkably, compounds 4a and 4d were the most potent in suppressing cell proliferation, with an IC50 value range of 4–6.5 µM. Flow cytometry analysis indicated that both compounds halted cell progression at the G2/M phase and induced apoptosis in a dose-dependent manner. RT-PCR and Western blot analyses also showed that both compounds effectively induced apoptosis by upregulating the expression of proapoptotic factors while downregulating that of antiapoptotic factors. In vivo animal toxicity assays performed in zebrafish embryos indicated that compound 4d was more toxic than compound 4a, with compound 4d inducing multiple levels of teratogenic phenotypes in zebrafish embryos at a sublethal concentration. Moreover, both compounds perturbed the hematopoiesis process in developing zebrafish embryos. Collectively, our data suggest that compounds 4a and 4d have the potential to be used as antileukemic agents. 相似文献
394.
Haniyeh Tahzibi Saeid Azizian Sabine Szunerits Rabah Boukherroub 《Advanced Engineering Materials》2023,25(19):2300197
Recently, a straightforward method for the preparation of a Janus carbon cloth (Janus-CC) is reported. The method relies on polydimethylsiloxane (PDMS) coating, followed by flame exposure of one face of the PDMS-coated CC. The nonexposed to the flame face of the Janus-CC is superhydrophobic, while the exposed to the flame face is superhydrophilic. Underwater, the superhydrophobic face shows superaerophilicity, while the supherhydophilic face shows superaerophobicity. A tethered gas bubble onto the superhydrophobic face has a paraboloid of revolution shape due to the cohesion force between the bubble and the gaseous film. Herein, the geometrical parameters of underwater tethered gas bubbles onto the Janus-CC are obtained, and the tendency of Janus-CC for capturing of bubbles is interpreted based on the derived Gibbs free-energy change equation. It is experimentally observed that a small sited bubble moves toward the bigger one through the formed gaseous film, but this observation cannot be interpreted based on the classical Young–Laplace equation because here the smaller bubble has bigger curvature radius. Herein, a modified Young–Laplace equation is derived and applied for interpretation of the movement of a small bubble toward the bigger one. Also, the buoyancy force for a sited bubble on the gaseous film is discussed. 相似文献
395.
Zirconium alloys are highly desirable in nuclear applications due to their transparency to thermal energy neutrons and for their high corrosion resistance. The main objective of this study is to investigate the fretting wear mechanism of Zr–2.5%Nb alloy. The experimental work was carried out in air at 265 °C, using a specially designed fretting wear tribometer. The transfer of material, the change in the wear volume and the maximum wear depth with the number of cycles were measured through 3D mapping of the topography of the fretted surface. SEM and Fourier Transform Infrared Interferometry methods were used to examine the microspall pits and to measure the distribution of the thickness of oxide layer in the fretting region. For relatively small slip amplitude, the results showed that the fretting wear mechanism is initially dominated by adhesion and abrasion actions and then by delamination and surface fatigue. The time variation of the wear losses was shown to be cyclic until a steady state value is reached. At high slip amplitudes, however, abrasion and delamination are the only dominant wear mechanisms. The volumetric wear losses were found to decrease monotonically with the number of cycles. A novel approach was introduced, whereby the thermal and electrical contact resistances of the fretting interface are simultaneously measured. The results demonstrated the potential use of this non-intrusive approach for real-time monitoring of the fretting wear mechanism. 相似文献
396.
Souhila AbaciBelkacem Nessark Rabah BoukherroubKamal Lmimouni 《Thin solid films》2011,519(11):3596-3602
The analysis of the electrochemical and spectroscopic properties of a composite material obtained starting from the polyaniline and TiO2 in H2SO4 medium, using cyclic voltamperometry, shows three redox couples characteristic of the different oxidation and reduction states of produced polymer. The electroactivity of the composite in acid medium was better than that obtained in basic medium. The impedance spectroscopy study shows that the resistance of the film increases with the aniline concentration, but is not significantly affected by the amount of TiO2 incorporated in polymer. The increase of pH decreases the resistance of the films and consequently increases its conductivity. 相似文献
397.
Mohamed M. Ibrahim Amine Mezni Mohammed Alsawat Tushar Kumeria Arwa Alrooqi Abdallah A. Shaltout Sameh I. Ahmed Rabah Boukherroub Mohammed A. Amin Tariq Altalhi 《国际能源研究杂志》2020,44(8):6725-6744
A newly synthesized zinc(II) complex, namely tert-butyl N-(2 mercaptoethyl)carbamatozinc(II) complex [Zn(Boc-S)2] (Boc = tert-butyl N-[2-mercaptoethyl]carbamate), has been used as an organozinc precursor for the production of crystalline ZnO and ZnO/TiO2 nanoparticles. The synthesized complex and the obtained nanomaterials were fully characterized using various spectroscopic and surface analysis techniques. Their surface morphology, chemical purity and stoichiometry have been investigated by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) as well as X-ray fluorescence. The synthesized Zn(II) molecular complex, ZnO and ZnO/TiO2 nanomaterials have been tested in alkaline aqueous solution (1.0 MNaOH) for the hydrogen evolution reaction (HER) using various electrochemical techniques. The results revealed high HER catalytic performance of ZnO and ZnO/TiO2 cathode materials, with the latter exhibiting higher catalytic activity recording an exchange current density (jo) of 0.3 mA cm−2. This current value, which approaches that of Pt wire (0.5 mA cm−2), cross-sectional area ~0.008 cm2, is about 11 and 100 times greater than those measured for ZnO alone (0.028 mA cm−2) and TiO2 alone (0.0032 mA cm−2), respectively. Moderate catalytic activity was recorded for the complex catalyst, namely GC-Zn(Boc-S)2 with jo value of (0.01 mA cm−2). Tafel slope values of 130 and 122 mV dec−1 were calculated for ZnO and ZnO/TiO2, respectively. Such Tafel slope values, which are close to that of the Pt wire (120 mV dec−1), referred to a Volmer-controlled HER kinetics. Other important electrochemical parameters describing the kinetics of the HER, such as roughness factor (Rf) and turnover frequency (TOF) were also estimated and discussed. The high numerical values of the various HER kinetic parameters recorded for the ZnO/TiO2 catalyst, in addition to its high stability and durability (stable for up to 10 000 continuous cathodic polarization cycles), besides maintaining its morphology and chemical composition after stability test (confirmed from SEM/EDX and XRD examinations), located it in a privileged position among the most efficient HER electrocatalysts reported in the literature. 相似文献
398.
Frederik Klauser Slimane Ghodbane Rabah Boukherroub Sabine Szunerits Doris Steinmüller-Nethl Erminald Bertel Norbert Memmel 《Diamond and Related Materials》2010,19(5-6):474-478
Various oxidation techniques (plasma-beam, sulfo-chromic acid, UV-ozone, heating in air) were applied to single-crystalline (111) and (100) diamond surfaces as well as nanocrystalline diamond (NCD) films and analyzed by X-ray photoelectron spectroscopy (XPS) with respect to oxygen content and type of carbon–oxygen groups formed upon oxidation. Due to their increased surface, NCD films show a significantly higher oxygen uptake as compared to their single-crystal counterparts. No marked differences were observed between the different oxidation techniques. For all oxidation techniques used, several carbon–oxygen groups are simultaneously present on the surface. The relative fraction of singly-oxidized carbon atoms (attributed to isolated ether or epoxy-like groups) generally decreases slightly with increasing oxygen content, but always remains the dominating species. 相似文献
399.
J. Wang S.Q. Zhang J. Shen Y.Z. Guo S.M. Attia B. Zhou Z.Q. Lai G.Z. Zheng Y.S. Gui 《Journal of Porous Materials》2001,8(2):167-170
Carbon aerogels are prepared by sol-gel polymerization and supercriticle drying. By controlling the mass ratio of reactants and the molar ratio of resorcinol to catalyst (R/C), carbon aerogels with different microstructure can be developed. Hall effect is measured by Van der Bow method. The results show that the electrical conductivity increases with increasing density of carbon aerogel, and Hall mobility at high temperature is nearly constant, while at low temperature the absolute value of Hall mobility increases linearly with decreasing temperature. The abnormal sign of Hall mobility is probably related to the microstructure of carbon aerogels, which influence the transport path of carriers. 相似文献
400.
Fatima Boumechhour Kerbachi Rabah Chikbouni Lamine Benmenni Med Said 《Water and Environment Journal》2013,27(1):114-119
Coagulation/flocculation process, Fenton oxidation and combinations between them were studied, aiming to provide an efficient method for the treatment of partially stabilized leachates. Leachates were collected from a municipal landfill site, samples containing around 3800 mg/L COD, BOD5/COD ratio about 0.11 and pH around 8. The sequence of stages implemented was: (a) coagulation/flocculation; (b) Fenton oxidation; (c) coagulation/flocculation followed by Fenton oxidation which resulted in a best COD removal (63.62%) and (d) Fenton oxidation followed by coagulation/flocculation. 相似文献