Dependence of chaotic behavior on optical properties and electrostatic effects in double beam torsional Casimir actuation

We investigate the influence of Casimir and electrostatic torques on double beam torsional microelectromechanical systems with materials covering a broad range of conductivities of more than three orders of magnitude. For the frictionless autonomous systems, bifurcation and phase space analysis shows that there is a significant difference between stable and unstable operating regimes for equal and unequal applied voltages on both sides of the double torsional system giving rise to heteroclinic and homoclinic orbits, respectively. For equal applied voltages, only the position of a symmetric unstable saddle equilibrium point is dependent on the material optical properties and electrostatic effects, while in any other case there are stable and unstable equilibrium points are dependent on both factors. For the periodically driven system, a Melnikov function approach is used to show the presence of chaotic motion rendering predictions of whether stiction or stable actuation will take place over long times impossible. Chaotic behavior introduces significant risk for stiction, and it is more prominent to occur for the more conductive systems that experience stronger Casimir forces and torques. Indeed, when unequal voltages are applied, the sensitive dependence of chaotic motion on electrostatics is more pronounced for the highest conductivity systems.Comment: 24 pages, 11 figure

Comparing the effects of alcoholic extract of ginseng with itraconazole against Candida albicans and Candida krusei

Background: Candidiasis is a prevalent disease which is caused by different species of Candida. Herbal drugs (e.g. ginseng) were traditionally administrated for the treatment of different diseases. This study was carried out to compare the effect of alcoholic extract of ginseng with Itraconazole against Candida albicans (C. albicans) and Candida krusei (C. krusei). Material and Methods: This cross-sectional study was crried out on 22 and 8 species of C.albicans and 8 C.krusei, respectively which were isolated from vagina, urine and sputum of the patients. Using the CLSI M27 and disk diffusion methods the susceptibility test was done by Itraconazole (10 µg) and ginseng extract (1, 2, 4, 8, 16, 32, 64 and 128 mg.ml-1). The standard species of C. albicans (PTCC 5027) and C. Krusei (PTCC 5295) were used for the quality control purposes. Results: The lowest and highest minimum inhibitory concentration (MIC) for C. albicans and C. Kruzei was 0.0625 and 0.5 μg.ml-1, respectively for Itraconazole using the microdilution method. However, the lowest MIC and minimum fungal concentration (MFC) for alcoholic extract was 64 mg.ml-1 .The highest inhibition zone for C. albicans was 14 and 14-32 mm for alcoholic extract and Foritraconazole, respectively. Using the two methods no significant difference was seen between the alcoholic extract of ginseng (64 and 128 mg.ml-1) and the drug. (P<0.05) Conclusion: Considering the MICs and disk diffusion results, the ginseng extract (64,128 mg.ml-1) shows considerable antifungal effects compared to Itraconazole

A comparison between gastroesophagheal ultrasonography vs. barium swallow in determining the pattern of gastroesophageal reflux in a pediatric population

Background: Gastroesophageal reflux disease (GERD) is one of the most common gastrointestinal pathology in infants and young children. Ultrasonography (US) has been considered to be a reliable diagnostic tool for GERD but the severity of GERD and the clinical implications based on imaging findings has not been evaluated. Aims: To compare the diagnostic value of lower esophageal US with that of barium swallow in demonstrating the severity of GERD. Materials and methods: Fifty one pediatric patients, age between 1 month to 12 years, 34 male and 17 female with clinical suspicion of GERD were included. The patients were initially submitted to barium swallow (BS) and subsequently to transabdominal US. During BS, the number of gastroesophageal reflux episodes was documented in a 5-minute period. Transabdominal US documented the number and duration of reflux episodes during a 5-minute period, the angle of His, mucosal thickness, and intraabdominal esophageal length (IAEL). Results: Duration and number of reflux episodes in US were significantly higher in patients that had severe gastroesophageal refluxes at BS. At US the cutoff point of 9.5 seconds (sensitivity 80, specificity 60) for reflux duration and more than 2 episodes in 5 minute ultrasound study (sensitivity 75, specificity 58) were defined to correlate with severe gastroesophageal reflux at BS.The angle of His, the esophageal wall mucosal thickness, and the IAEL did not correlate with the severity of GERD detected in BS. Conclusion: US can predict the severity of GERD. Therefore, except in the case of specific patients in whom mechanical causes are suspected to be responsible for GERD, BS can be replaced by US

Nonlinear actuation of micromechanical Casimir oscillators with topological insulator materials toward chaotic motion:Sensitivity on magnetization and dielectric properties

We have investigated the dynamical actuation of micro-electromechanical systems under the influence of attractive and repulsive Casimir forces between topological insulator plates as a function of their dielectric function and coating magnetization. The analysis of the Casimir force in the limit of strong and weak magnetization shows that the attractive force, which is produced for plate magnetizations in the same direction, is greater than the repulsive force that is produced for opposite magnetizations. However, both forces remain comparable for intermediate magnetizations. Moreover, for weak magnetization, the attractive force becomes stronger for an increasing dielectric function, while the opposite occurs for the repulsive force. On the other hand, increasing magnetization decreases the influence of the dielectric function on both the repulsive and attractive forces. Furthermore, for conservative systems, bifurcation and phase portrait analysis revealed that increasing magnetization decreases the regime of stable operation for devices with attractive forces, while their operation remains always stable under the presence of repulsive forces. Finally, for non-conservative periodically driven systems, the Melnikov function and Poincaré portrait analysis show that for magnetizations in the same direction leading to strong attractive Casimir forces, chaotic motion toward stiction is highly likely to occur preventing the long-term prediction of actuating dynamics. A remedy for this situation is obtained by the application of any magnetization in opposite directions between the interacting surfaces since the repulsive force makes it possible to prevent stiction

The predictive value of HLA-DR matching and cytokine gene polymorphisms in renal allograft acute rejection: A living-unrelated donor (LURD) study

Background: In addition to Human Leukocyte Antigens (HLA) compatibility, gene polymorphisms in cytokines might also be important in the quality of allogeneic immune response. Objective: To evaluate the influence of HLA-DR matching and a number of cytokine gene polymorphisms on acute rejection after living-unrelated donor (LURD) kidney transplantation. Methods: A total of 42 renal transplants performed at Hashemi Nejad Kidney Hospital (Tehran/Iran) and followed up for 3 months post-transplantation were included. Using PCR-SSP, HLA-DR alleles (DR1-18) of recipients and donors and gene polymorphisms in TNF-a, TGF-b1, IL-10, IL-6, and IFN-γ of recipients were determined. Results: Acute rejection was observed in 11(26.2) of renal recipients. The frequency of one and two HLA-DR mismatches in rejector group was 2(18.2) and 9(81.8) and in non-rejector group was 13(41.9) and 17(54.8), respectively. HLA-DR incompatibility was not significantly higher in rejector (1.82±0.40) compared with non-rejector (1.52±0.57) recipients (P=0.069) and more than half of non-rejectors had completely mismatched HLA-DR antigens with donors. Polymorphisms associated with the mentioned cytokines had no correlation with acute rejection. Conclusion: The predictive value of HLA-DR mismatching for acute rejection is not as prominent in LURD kidney transplantation as in the cadaveric one. In addition, we failed to demonstrate an association between combined cytokine genotypes and HLA-DR matching with acute rejection. Further and more detailed immunogenetic investigations are required in order to have a better prediction of the transplant outcome

Immunomodulatory effects of human amniotic epithelial cells on naive CD4+ T cells from women with unexplained recurrent spontaneous abortion

Abstract Introduction Immune imbalance at the maternal-fetal interface plays a fundamental role in the pathogenesis of unexplained recurrent spontaneous abortion (URSA). Human amniotic epithelial cells (hAECs) possess pregnancy-friendly immunomodulatory effects. Here, we investigated how function of naive CD4+ T cells from URSA patients is affected by hAECs. Methods Phenotypic characteristics of hAECs were determined by flow cytometry and their effect on proliferation of allogeneic peripheral blood mononuclear cells (PBMCs) was evaluated by a BrdU cell proliferation assay. Naive CD4+ T cells were isolated from 25 URSA patients and 5 healthy women and co-cultured with hAECs. Immunomodulatory effects of hAECs on cytokines profile, proliferation of stimulated CD4+ T cells and induction of regulatory T cells (Tregs) were assessed by ELISA and flow cytometry, respectively. Functional competency of Tregs was evaluated in an allogeneic mixed lymphocyte reaction (MLR) system. Results hAECs did not elicit allogeneic proliferative responses of PBMCs, inhibited proliferation of naive CD4+ T cells, induced production of Th2 and suppressed production of Th1 and Th17 cytokines. hAECs showed the ability to induce differentiation of Tregs and production of transforming growth factor-beta1 (TGF-β1) and interleukin-10 (IL-10). This ability was found to be superior in control subjects compared to URSA patients. Indeed, Tregs generated in the presence of hAECs expressed higher levels of CTLA-4 compared to Tregs generated in their absence and restrained the proliferation of autologus PBMCs in MLR system. Conclusion Based on these findings, hAECs can be considered as one potential candidate in immunotherapy of patients with URSA. Keywords Immunomodulatory effects Amniotic epithelial cells Naive T cells Unexplained recurrent spontaneous abortio

Sensitivity of nonequilibrium Casimir forces on low frequency optical properties toward chaotic motion of microsystems:Drude vs plasma model

Here, we investigate the sensitivity of nonequilibrium Casimir forces to optical properties at low frequencies via the Drude and plasma models and the associated effects on the actuation of microelectromechanical systems. The stability and chaotic motion for both autonomous conservative and nonconservative driven systems were explored assuming good, e.g., Au, and poor, e.g., doped SiC, interacting conductors having large static conductivity differences. For both material systems, we used the Drude and plasma methods to model the optical properties at low frequencies, where measurements are not feasible. In fact, for the conservative actuating system, bifurcation and phase space analysis show that the system motion is strongly influenced by the thermal nonequilibrium effects depending on the modeling of the optical properties at low frequencies, where also the presence of residual electrostatic forces can also drastically alter the actuating state of the system, depending strongly on the material conductivity. For nonconservative systems, the Melnikov function approach is used to explore the presence of chaotic motion rendering predictions of stable actuation or malfunction due to stiction on a long-term time scale rather impossible. In fact, the thermal effects produce the opposite effect for the emerging chaotic behavior for the Au-Au and SiC-SiC systems if the Drude model is used to model the low optical frequencies. However, using the plasma model, only for the poor conducting SiC-SiC system, the chance of chaotic motion is enhanced, while for the good conducting Au-Au system, the chaotic behavior will remain unaffected at relatively short separations (<2 μm)

Dependence of non-equilibrium Casimir forces on material optical properties toward chaotic motion during device actuation

The sensitivity of nonequilibrium Casimir forces on material optical properties can have strong impact on the actuation of devices. For this purpose, we considered nonequilibrium Casimir interactions between good and poor conductors, for example, gold (Au) and highly doped silicon carbide (SiC), respectively. Indeed, for autonomous conservative systems, the bifurcation and phase portrait analysis have shown that the nonequilibrium Casimir forces can have significant impact on the stable and unstable operating regimes depending on the material optical properties. At a few micrometer separations, for systems with high conductivity materials, an increasing temperature difference between the actuating components can enhance the stable operation range due to the reduction of the Casimir force, while for the poor conductive materials, the opposite takes place. For periodically driven dissipative systems, the Melnikov function and Poincare portrait analysis have shown that for poor conductive systems, the nonequilibrium Casimir forces lead to an increased possibility for chaotic behavior and stiction with an increasing temperature difference between the actuating components. However, for good conducting systems, the thermal contribution to Casimir forces reduces the possibility for chaotic behavior with increasing temperature, as comparison with systems without thermal fluctuations shows. Nevertheless, the positive benefit of good conductors toward increased actuation stability and reduced the chaotic behavior under nonequilibrium conditions can be easily compromised by any voltage application. Therefore, thermal, nonequilibrium Casimir forces can influence the actuation of devices toward unstable and chaotic behavior in strong correlation with their optical properties, and associated conduction state, as well as applied electrostatic potentials

Fas and fas-ligand promoter polymorphisms in hepatitis b virus infection

Background: The FAS and FAS-Ligand (FASL) system is an important apoptosis pathway in the liver. The FAS-mediated pathway functions by binding the FASL on the activated cytotoxic T lymphocytes and Natural Killer (NK) cells to the FAS receptor on infected hepatocytes. FAS and FASL polymorphisms, which are related to apoptosis, might influence the outcome of Hepatitis B Virus (HBV) infection. Objectives: Thus, the present study aimed to determine if FAS and FASL promoter polymorphisms are associated with the clinical outcome of HBV infection. Patients and Methods: DNA samples were obtained from the infected individuals including chronic carrier (n = 50), chronic hepatitis (n = 50), cirrhosis (n = 25), naturally recovered (n = 26) and compared with those of their matched healthy controls (n = 100). Genotyping for polymorphisms of FAS-670 A/G and -1377 G/A, and FASL -844 C/T was performed using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assays. Results: Multiple analyses for genetic association of FAS and FASL polymorphisms were not statistically different between HBV patients (n = 125) and healthy controls (n = 100). However, genotype and allele frequencies of FASL-844 C/T were significantly different between recovered individuals and patients with cirrhosis (P = 0.02 and P=0.01, respectively). Whereas, FAS-670A/G and -1377G/A polymorphisms were similarly distributed in these two groups (P = 0.8 and P = 0.47, respectively). Conclusions: The current study results showed that bearing -844T allele in FASL promoter region has a protective effect on cirrhosis and is involved in recovery from infection. In conclusion, it is proposed that HBV infection outcome might be influenced by FASL-844C/T polymorphism through alteration in apoptosis of hepatocytes. © 2015, Kowsar Corp