Bending analysis of sandwich panel composite with a re-entrant lattice core using zig-zag theory.

The sandwich panel structures have been widely used in many industrial applications because of their high mechanical properties. The middle layer of these structures is very important factor in controlling and enhancing their mechanical performance under various loading scenarios. The re-entrant lattice configurations, are prominent candidates that can be used as the middle layer in such sandwich structures because of several reasons namely the simplicity in tuning their elastic (e.g., values of Poisson's ratio and elastic stiffness) and plastic (e.g., high strength-to-weight ratio) properties by only adjusting the geometrical features of the constituting unit cells. Here, we investigated the response of a three-layered sandwich plate with a re-entrant core lattice under flexural bending using analytical (i.e., zig-zag theory), computational (i.e., finite element) and experimental tests. We also analyzed the effects of different geometrical parameters (e.g., angle, thicknesses, and length to the height ratio of unit cells) of re-entrant lattice structures on the overall mechanical behavior of sandwich structures. We found that the core structures with auxetic behavior (i.e., negative Poisson's ratio) resulted in a higher bending strength and a minimum out-of-plane shear stress as compared to those with conventional lattices. Our results can pave way in designing advanced engineered sandwich structures with architected core lattices for aerospace and biomedical applications.

Designing a new bispecific tandem single-chain variable fragment antibody against tumor necrosis factor-α and interleukin-23 using in silico studies for the treatment of rheumatoid arthritis.

Rheumatoid arthritis disease is a chronic auto-immune inflammatory disease that mainly causes synovial joint inflammation and cartilage destruction. The tumor necrosis factor-α (TNF-α) is a pivotal cytokine that plays an important role in rheumatoid arthritis. The treatments focusing on a single cytokine inhibition are clinically able to produce meaningful responses in only about half of the treated patients due to multiple cytokines involved in this disease. In the present study, a bispecific tandem single-chain variable fragment was designed in order to suppress both human tumor necrosis factor-α and interleukin-23 (IL23) as a potential therapeutic drug candidate for this disease. To do so, at first, eight bispecific tandem single-chain variable fragment models were built against tumor necrosis factor-α and interleukin-23 cytokines with different domain orders by the homology modeling, and then 50 ns molecular dynamics simulation was performed for each one and then structural properties were exploited. The MD simulation results indicate the fact that the domains' order strongly affects tandem single-chain variable fragment properties, and in overall, the fragment VLAIL23+Linker+VHAIL23+linker+VLATNF+Linker +VHATNF +His6 (VL and VH are light and heavy chain variable fragments and AIL23 and ATNF are anti-interleukin 23 and anti-tumor necrosis factor-α, respectively, and His6 is the six histidine) not only separated antibody domains accurately but also had better stability and solvation free energy. Therefore, this structure can be considered as an effective potential drug for rheumatoid arthritis. It is expected that the findings of this research could shed a light on the treatment approaches of the rheumatoid arthritis disease.

Ultraweak photon emission in the brain.

Besides the low-frequency electromagnetic body-processes measurable through the electroencephalography (EEG), electrocardiography (ECG), etc. there are processes that do not need external excitation, emitting light within or close to the visible spectra. Such ultraweak photon emission (UPE), also named biophoton emission, reflects the cellular (and body) oxidative status. Recently, a growing body of evidence shows that UPE may play an important role in the basic functioning of living cells. Moreover, interesting evidences are beginning to emerge that UPE may well play an important role in neuronal functions. In fact, biophotons are byproducts in cellular metabolism and produce false signals (e.g., retinal discrete dark noise) but on the other side neurons contain many light sensitive molecules that makes it hard to imagine how they might not be influenced by UPE, and thus UPE may carry informational contents. Here, we investigate UPE in the brain from different points of view such as experimental evidences, theoretical modeling, and physiological significance.

The glycoprofile patterns of endothelial cells in usual interstitial pneumonia.

BACKGROUND: The pathological classification of cryptogenic fibrosing alveolitis has been a matter of debate and controversy for histopathologists. OBJECTIVE: To identify and specify the glycotypes of capillary endothelial cells in usual interstitial pneumonia (UIP) compared to those found in normal tissue. METHODS: Sections of formalin-fixed, paraffin-embedded blocks from 16 cases of UIP were studied by lectin histochemistry with a panel of 27 biotinylated lectins and an avidin-peroxidase revealing system. RESULTS: High expression of several classes of glycan was seen de novo in capillary endothelial cells from patients with UIP including small complex and bi/tri-antennary bisected complex N-linked sequences bolund by Concanavalin A and erythro-phytohemagglutinin, respectively, GalNAca1 residues bound by Helix pomatia and Maclura pomifera agglutinins, and L-fucosylated derivatives of type II glycan chains recognized by Ulex europaeus agglutinin-I. Glycans bound by agglutinins from Lycopersicon esculentum (ß1,4GlcNAc) and Wisteria floribunda (GalNAc) as well as GlcNAc oligomers bound by Phytolacca americana and succinylated Wheat Germ agglutinin were also seen in the capillary endothelial cells of UIP. In contrast, L-fucosylated derivatives of type I glycan chains were absent in cells from cases of UIP when Anguilla anguilla agglutinin was applied, unlike the situation in normal tissue. CONCLUSION: These results may indicate existence of two distinct populations of endothelial cell in UIP with markedly different patterns of glycosylation, reflecting a pattern of differentiation and angiogenesis, which is not detectable morphologically.

The toxic effects of silver nanoparticles on blood mononuclear cells.

BACKGROUND: Nanoparticles have become one of the leading technologies over the past two years. The extensive use of nanoparticles has raised great concern about their occupational fate and biological effects. With an increase in the production and use of nanomaterial, it is more likely to get exposed to them occupationally and environmentally. OBJECTIVE: To assess the toxicity of silver nanoparticles on human mononuclear cells. METHODS: In this in vitro experimental study, suspensions of blood mononuclear cells from 10 young healthy men were incubated with 10-nm silver nanoparticles in different concentrations (range: 1-500 µg/mL) for 6 and 24 hours by MTT assay. Positive and negative controls were used for comparison. RESULTS: After 6 hours of exposure, 10.9% to 48.4% of the cells died. After 24 hours of exposure, the rate ranged from 56.8% to 86.3%. Regardless of the exposure time, the maximum cytotoxicity was observed at the concentration of 500 µg/mL of silver nanoparticles. By increasing the exposure time to 24 hours, the cytotoxicity of nanoparticles substantially increased at all concentrations. Cell death was significantly higher when compared to the controls (p<0.01). CONCLUSION: Silver nanoparticles possess both time- and dose-dependent cytotoxicity and can thus be considered as very toxic for mononuclear cells.

Survey of ownership and use of mobile phones among medical science students in Yazd.

As the use of mobile phones is increasing every day, public concern about possible adverse health effects of exposure to radio frequency electromagnetic fields (rf-emf) is also growing. Despite the extensive use of mobile phones, little is known about the pattern of mobile phone ownership and its use by the general population and students. The aim of this study was to assess the pattern of ownership and use of mobile phones in medical science students and their views about any possible negative effects. The current cross-sectional study was conducted on 309 selected Medical Science students who were selected from Yazd Medical Sciences University using a self administrated questionnaire. The mean talking time and listening to music on the mobile phone was 28.3 +/- 50.5 and 51.9 +/- 81.5 min day(-1), respectively. They also received or sent a mean of 18.8 +/- 37 text messages. Participants reported that location wise, the use of cell phones at home was 87.2% followed by street (79.6%), classroom (37.6%), during driving (18.6%) and in the library (17.8%), respectively. Keeping at pace with changes in community and technology, including mobile phones and their effects on university environments, it seems that responsible departments or managers must predict their possible effects and establish new regulations, accordingly.

Application of a hazard and operability study method to hazard evaluation of a chemical unit of the power station.

BACKGROUND: The aim of this study was to identify the hazards, evaluate their risk factors and determine the measure for promotion of the process and reduction of accidents in the chemical unit of the power station. METHODS: In this case and qualitative study, HAZOP technique was used to recognize the hazards and problems of operations on the chemical section at power station. Totally, 126 deviations were documented with various causes and consequences. RESULTS: Ranking and evaluation of identified risks indicate that the majority of deviations were categorized as "acceptable" and less than half of that were "unacceptable". The highest calculated risk level (1B) related to both the interruption of acid entry to the discharge pumps and an increased density of the acid. About 27% of the deviations had the lowest risk level (4B). CONCLUSION: The identification of hazards by HAZOP indicates that it could, systemically, assess and criticize the process of consumption or production of acid and alkali in the chemical unit of power plant.