Preparation and characterisation of thickness dependent nano-structured ZnS thin films by sol–gel technique

Zinc sulfide (ZnS) thin films of different thickness were coated on glass substrates by the sol–gel dip-coating technique. Thickness dependent structural and optical properties of the films were studied in detail. X-ray diffraction (XRD) analysis indicated that the films had mixture of cubic (β) and hexagonal (α) phases with cubic (β) phase being predominant. Scanning electron microscope (SEM) showed that the film surfaces were smooth and crack free. Energy dispersive X-ray (EDX) measurement showed no impurity in the ZnS compound with elemental concentration of Zn/S being 50.38/49.62. Optical measurements showed that optical transmittance of the films were decreased in the visible range as the film thickness increased and band gap of the thin films were estimated to be about 3.61, 3.56, and 3.39?eV for the films with thickness of 100, 220, and 360?nm, respectively. Reactive indices and extinction coefficients of the films were measured by Spectroscopic Ellipsometer. Both the refractive index (n) and extinction coefficient (k) of the films were increased as the film thickness decreased. Electrical measurements showed that the resistivity of the films were decreased as the substrate temperature and film thickness increased.     

Microstructure–permeability relation of porous β-Si3N4 ceramics

Porous β-Si₃N₄ ceramics with two distinct structures were produced by using two different Si₃N₄ sources to investigate the relationship between microstructure and permeability. Results showed that regardless of pore amount, size of pore channels, shape-distribution of β-Si₃N₄ grains are more effective on permeability of porous Si₃N₄ ceramics. Higher permeability and lower contribution of inertial forces was obtained by microstructure consists of coarse and equiaxed grains even at lower porosity amount. Calculated Forchheimer number (F_o) and measured the local breadth of a pore also supported the effect of microstructure on permeability.     

Survey of 55 Turkish Salvia taxa for their acetylcholinesterase inhibitory and antioxidant activities

In the current work, our target was to screen inhibitory potentials of 55 Turkish Salvia taxa, 28 of which are endemic, against acetylcholinesterase (AChE), which is a chief enzyme in pathogenesis of Alzheimer’s disease (AD). The dichloromethane, ethyl acetate, and methanol extracts prepared from 55 Salvia taxa were tested for their AChE inhibitory activity at 25, 50, and 100 μg/ml using an ELISA microplate reader. The extracts were also screened for their scavenging effect against DPPH radical and iron-chelating capacity. Total phenol and total flavonoid contents of Salvia fruticosa were determined. Among the 165 Salvia extracts screened, only the dichloromethane extract of S. fruticosa showed inhibition towards AChE at 100 μg/ml having 51.07% of inhibition, while only the dichloromethane and ethyl acetate extracts of Salvia cilicica had a notable iron-chelating capacity at 100 μg/ml having 54.71% of chelating capacity. Most of the extracts showed remarkable scavenging effect against DPPH radical.     

Rating and Reliability of Existing Bridges in a Network

Currently, the load rating is the method used by State DOTs for evaluating the safety and serviceability of existing bridges in the United States. In general, load rating of a bridge is evaluated when a maintenance, improvement work, change in strength of members, or addition of dead load alters the condition or capacity of the structure. The AASHTO LRFD specifications provide code provisions for prescribing an acceptable and uniform safety level for the design of bridge components. Once a bridge is designed and placed in service, the AASHTO Manual for Condition Evaluation of Bridges provides provisions for determination of the safety and serviceability of existing bridge components. Rating for the bridge system is taken as the minimum of the component ratings. If viewed from a broad perspective, methods used in the state-of-the-practice condition evaluation of bridges at discrete time intervals and in the state-of-the-art probability-based life prediction share common goals and principles. This paper briefly describes a study conducted on the rating and system reliability-based lifetime evaluation of a number of existing bridges within a bridge network, including prestressed concrete, reinforced concrete, steel rolled beam, and steel plate girder bridges. The approach is explained using a representative prestressed concrete girder bridge. Emphasis is placed on the interaction between rating and reliability results in order to relate the developed approach to current practice in bridge rating and evaluation. The results presented provide a sound basis for further improvement of bridge management systems based on system performance requirements.     

Comparison of two isolation methods for essential oil from rosemary leaves: Hydrodistillation and microwave hydrodiffusion and gravity

Traditional hydrodistillation (HD) and innovative Microwave Hydrodiffusion and Gravity (MHG) methods have been compared and evaluated for their effectiveness in the isolation of essential oil from fresh Rosmarinus officinalis leaves. The microwave method offers important advantages over traditional alternatives, namely: shorter isolation times (15 min against 3 h for hydrodistillation), environmental impact (energy cost is fairly higher to perform HD than that required for rapid MHG isolation), cleaner features (as no residue generation and no water or solvent used), increases antimicrobial activities, increases antioxidant activity and provides a more valuable essential oil (with high amount of oxygenated compounds). It offers also the possibility for a better reproduction of natural aroma of the essential oil from rosemary leaves than the HD essential oil. Moreover, microwave procedure yielded essential oils that could be analysed or used directly without any clean-up, solvent exchange or centrifugation steps. Scanning electron microscopy shows important structural changes for MHG extraction in contrast to those obtained by HD. Electron micrographs show clearly that the cells are broken and damaged during microwave treatment. Finally, the mechanism of Microwave Hydrodiffusion and Gravity is proposed and discussed.     

The effects of deposition parameters on surface morphology and crystallographic orientation of electroless Ni-B coatings

Electroless Ni-B coatings were deposited on AISI 304 stainless steels by electroless deposition method, which was performed for nine different test conditions at various levels of temperature, concentration of NaBH₄, concentration of NiCl₂, and time, using the Taguchi L₉(3⁴) experimental method. The effects of deposition parameters on the crystallographic orientation of electroless Ni-B coatings were investigated using SEM and XRD equipment. SEM analysis revealed that the Ni-B coatings developed six types (pea-like, maize-like, primary nodular, blackberry-like or grapes-like, broccoli-like, and cauliflower-like) of morphological structures depending on the deposition parameters. XRD results also showed that these structures exhibited different levels of amorphous character. The concentration of NaBH₄ had the most dominant effect on the morphological and crystallographic development of electroless Ni-B coatings.     

A new type of poly(glycidyl methacrylate) microbeads with surface grafted iminodiacetic acid: Synthesis and characterization

In this study, firstly, uniform poly(glycidyl methacrylate) (PGMA) microbeads with an average diameter of 230 μm were synthesized by suspension polymerization of GMA monomer and ethylene glycol dimethacylate (EGDMA) crosslinker in the presence of benzoyl peroxide (BPO) initiator . Secondly, the PGMA microbeads obtained were modified with iminodiacetic acid (IDA) to afford a new type of microbeads carrying two pendant carboxylic acid groups on the surface. The IDA modification was followed by Attenuated Total Reflectance Fourier Transformed Infrared (ATR-FTIR) measurements. The surface morphology and thermal behavior of the PGMA and their modificated form were also characterized by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) techniques further confirming modification.     

Antioxidant capacities of Gundelia tournefortii L. extracts and inhibition on glutathione-S-transferase activity

Gundelia tournefortii L. is an important food source and a well-known medicinal plant in Eastern Anatolia. Therapeutic effects of medicinal plants are known to be closely related to their antioxidant capacities. Antioxidant activities of G. tournefortii, both for the aerial parts and seeds, were investigated by using both 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and lipid peroxidation inhibition methods. The seeds were found to have higher antioxidant potential than the aerial, with IC₅₀ values of 0.073 mg/mL for DPPH scavenging and 0.146 mg/mL for lipid peroxidation inhibition capacities. In addition, total phenolic contents of the Gundelia tournefortii L. extracts, especially the seed extracts correlates to its high antioxidant activity with 105.1 ± 8.7 μg gallic acid equivalents (GAEs) per mg of seed extract. Plant extracts with high phenolics content are known to have important effects on various enzymes, as well as glutathione-S-transferases, which are important detoxification enzymes in phase II systems with an important role in developing multi-drug resistance to chemotherapy in tumour cells. Consequently, the effects of G. tournefortii extracts on crude cytosolic glutathione-S-transferase was also studied and the seed extracts have shown effective inhibition of cytosolic GST activity, with an IC₅₀ of 97.51 μg/mL.     

Metals,including vanadyl and nickel porphyrins,in the oil shales of Timahdit,Morocco

Vanadyl and nickel porphyrins have been isolated from a Cretaceous oil shale (Timahdit, Morocco) by solvent extraction and chromatography. Electronic absorption spectrophotometry and mass spectrometry have been used in the determination of the nature and proportion of the isolated complexes. A distinction between the metal content associated with porphyrinic systems and that associated with inorganic materials is made on the basis of metal determinations carried out on the bituminous shale and on the extract of organic material; the concentration of V and Ni observed in organic material is comparable to that found in heavy crude oils but these metals, present in nearly identical amounts, are entirely coordinated to porphyrinic systems.