Genotypic heterogeneity and phenotypic variation among patients with type 2 Gaucher''s disease

Electrophysiological examination of the function of perceptive organs, like eye or cochlea, works up more and more interest in scientists to look for an objective method of vestibular end organ investigation. In many papers authors attempt to estimate the efficiency of vestibular organs after using angular or linear acceleration as stimulus, which required special and expensive apparatus. Papers that described vestibular evoked myogenic potentials (VEMPs) seem to be very promising. In this study an attempt was taken to obtain VEMPs with own modification of stimulus and response register. Preliminary examinations in 14 healthy volunteers were performed. Two subjects with sensorineural deafness on one side and symmetric, normal excitability of vestibular organs and 4 with bilateral hearing loss and unilateral weakness of vestibular excitability were examined. There were also 6 patients with only weakness of vestibular excitability. On the basis of practical observations, there is a possibility that evoked potentials were a result of stimulation of vestibular part of the inner ear--sacculus. The method of the study is objective, simple, secure and comfortable for patients.     

Investigation of factors affecting on viscosity reduction of sludge from Iranian crude oil storage tanks

Crude oil is a kind of water/oil emulsion, which the oil phase consists of organic molecules with different molecular weights such as alkanes, paraffin, asphaltene, and resins. Due to the change in physicochemical conditions during the production, transportation, storage, and refining, heavier molecules can precipitate from crude oil. Thus, viscous sludge formed at the bottom of storage tanks can cause many problems including reduction of storage capacity of tank, oil contamination, corrosion, repair costs, environmental pollution, etc. The reduction of sludge viscosity can be achieved by reduction of its interfacial tension. In this study, different chemical and physical factors, influencing prepared emulsions (made of sludge, water and surfactant), such as surfactants, solvents, temperature, pressure, and mixing conditions were investigated. Results showed that non-ionic surfactants (like bitumen emulsifier), and solvents (such as mixed xylene, AW-400, and AW-402), injection of additives, applying pressure, and mixing operations had a positive effect on reduction of emulsion viscosity. All experiments were carried out with sludge obtained from crude oil storage tanks at Kharg Island, Iran.     

Synthesis of mesoporous cobalt ferrite/hydroxyapatite core-shell nanocomposite for magnetic hyperthermia and drug release applications

In this study, cobalt ferrite/hydroxyapatite nanocomposite was developed by a new approach to design a uniform core-shell combination. The prepared powders were characterized by different techniques such as Brunauer–Emmett–Teller (BET) analyses, transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR), Vibrating-sample magnetometer (VSM), and field emission scanning electron microscopy (FESEM). TEM micrographs showed the formation of a uniform core/shell structure with a particle size of about 85$\pm 65$ nm. The controlled drug release experiments showed that the samples have a good drug loading capability and controlled delivery ability up to 50 h. Moreover, with different magnetic fields or different cobalt ferrite ratios to hydroxyapatite, it is possible to manipulate the amount of produced heat, making this composite promising for various kinds of magnetic hyperthermia-based treatment. Cytotoxicity of the nanocomposite was evaluated by MTT assay using MG63 cells. MTT and VSM results revealed that incorporating hydroxyapatite on cobalt ferrite nanoparticles' surface significantly increases cell compatibility, whereas it reduces magnetization saturation. The results suggest that cobalt ferrite/hydroxyapatite nanocomposite with multifunctionality and uniform structure has a great capability to be applied for medical uses.     

Adhesion and contact modeling and experiments in microelectromechanical systems including roughness effects

The intermolecular adhesive forces in microelectromechanical systems (MEMS) applications are very significant and can hinder normal operation of sensors and actuators as well as micro-engines where catastrophic adhesion and high friction could be promoted. It has been experimentally shown that surface texturing (roughening) decreases the effect of these forces. In this paper, a model that predicts the effects of roughness, on the adhesion and contact forces in MEMS interfaces is presented. The three key parameters used to characterize the roughness, the asymmetry and the flatness of a surface topography are the root-mean-square roughness (RMS), skewness and kurtosis, respectively. It is predicted that surfaces with high RMS, high kurtosis and positive skewness exhibit lower adhesion and are thus less prone to collapsing when they come into contact or near contact. Moreover, polysilicon films with different levels of roughness, asymmetry and peakiness (sharpness) were fabricated. Experiments were conducted to evaluate the adhesive pull-off forces associated with these films. The roughness characteristics of these films were also used in the model to predict the adhesive pull-off forces. Good agreement was obtained between the theoretical and experimental results. Such a model could be used to determine the critical characteristics of a microstructure prior to fabrication to prevent adhesion and lower friction in terms of surface roughness, mechanical properties and environment.     

Burning rates and surface characteristics of hydrogen-enriched turbulent lean premixed methane–air flames

The burning rates and surface characteristics of hydrogen-enriched turbulent lean premixed methane–air flames were experimentally studied by laser tomography visualization method using a V-shaped flame configuration. Turbulent burning velocity was measured and the variation of flame surface characteristics due to hydrogen addition was analyzed. The results show that hydrogen addition causes an increase in turbulent burning velocity for lean premixed CH₄–air mixtures when turbulent level in unburned mixture is not changed. Moreover, the increase of turbulent burning velocity is faster than that of the corresponding laminar burning velocity at constant equivalence ratio, suggesting that the kinetics effect is not the sole factor that results in the increase in turbulent burning velocity when hydrogen is added. The further analysis of flame surface characteristics and brush thickness indicates that hydrogen addition slightly decreases local flame surface density, but increases total flame surface area because of the increased flame brush thickness. The increase in flame brush thickness that results in the increase in total surface area may contribute to the faster increase in turbulent burning velocity, when hydrogen is added. Besides, the stretched local laminar burning velocity may be enhanced with the addition of hydrogen, which may also contribute to the faster increase rate of turbulent burning velocity. Both the variation in flame brush thickness and the enhancement in stretched local laminar burning velocity are due to the decreased fuel Lewis number when hydrogen is added. Therefore, the effects of fuel Lewis number and stretch should be taken into account in correlating burning velocity of turbulent premixed flames.     

69—THE MECHANICS OF SELF-PLYING STRUCTURES. PART I: MONOFILAMENT STRANDS

Analyses of the mechanics of self-plying structures developed for monofilament strands are presented, and an account is given of the experimental verification, by means of the use of rubber strands in simple twisting and plying experiments, of theoretical predictions of the extent of self-plying twist on the basis of monofilament pre-twist and filament properties.     

Nano-hydroxyapatite and nano-hydroxyapatite/zinc oxide scaffold for bone tissue engineering application

This research aims to evaluate the mechanical properties, biocompatibility, and degradation behavior of scaffolds made of pure hydroxyapatite (HA) and HA-modified by ZnO for bone tissue engineering applications. HA and ZnO were developed using sol-gel and precipitation methods respectively. The scaffolds properties were characterized using X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), atomic absorption (AA), and atomic force microscopy (AFM). The interaction of scaffold with cells was assessed using in vitro cell proliferation and alkaline phosphatase (ALP) assays. The obtained results indicate that the HA/ZnO scaffolds possess higher compressive strength, fracture toughness, and density—but lower hardness—when compared to the pure HA scaffolds. After immersing the scaffold in the SBF solution, more deposited apatite appeared on the HA/ZnO, which results in the rougher surface on this scaffold compared to the pure HA scaffold. Finally, the in vitro biological analysis using human osteoblast cells reveals that scaffolds are biocompatible with adequate ALP activity.     

Single phased silicate-containing calcium phosphate bioceramics: Promising biomaterials for periodontal repair

Tissue engineering using single-phased silicate–containing calcium phosphate bioceramic scaffolds is a promising and highly effective approach for periodontal repair, which provide an appropriate mechanical properties, proper degradation and good manufacturability. Both in vitro, and post-surgery evaluations demonstrated that they have advanced capability to stimulate osteogenesis/cementogenesis. However, the complex mechanisms of their action have not yet been clarified. It is clear that Ca²⁺, PO₄³- and SiO₄⁴ release profile (from the scaffold) directly affect on the osteogenesis and cementogenesis. Each of these ions, alone or committed together, modulates pathways upregulation leading to cell attachment, proliferation and differentiation, apatite formation/deposition, extracellular matrix formation and mineralization. Upregulating/downregulating a pathway may impress upregulation/downregulation of another pathway, and therefore provide a cyclic procedure which may affect both the release and absorption profiles of other ions. This review article aims to discuss how the ion releases could modulate signaling pathways’ upregulation. Further, this paper will elaborate the importance of using specialized engineering methods to prevent misinterpreting of the in vitro and in vivo investigations.