AN EFFICIENT NUMERICAL SCHEME TO DETERMINE THE PULL-IN PARAMETERS OF AN ELECTROSTATIC MICRO-ACTUATOR WITH CONTACT TYPE NONLINEARITY

ABSTRACT In this article, we present an efficient numerical scheme based on the Rayleigh-Ritz method to determine the pull-in parameters of electrostatically actuated microbeams exploiting contact type nonlinearity. A case of an electrostatically actuated cantilevered microbeam is first analyzed using the RayleighRitz energy technique. The deflection of the microbeam is approximated by a polynomial trial function. The principle of the stationary potential energy leads to a highly nonlinear algebraic equation, which is solved to determine the deflected shape of the microbeam. A novel voltage iteration algorithm is implemented to determine the critical voltage at which the pullin occurs. The analysis is then extended to the case of cantilever beam making use of the contact type nonlinearity to exhibit an extended travel range. The present case consists of a compression spring getting engaged at the cantilever tip at the critical point where the pull-in occurs. An increase in both travel range and pull-in voltage is observed with the introduction of the compression spring. A performance index is suggested, which combines the gain in the travel range together with the concomitant increase in the pull-in voltage. This index is used to determine the critical bound for the choice of the stiffness of the newly introduced compression member

Formulacija i evaluacija monolitnih matriksnih polimernih filmova za transdermalnu isporuku nitrendipina

The objective of the present work was to develop a suitable transdermal drug delivery system for nitrendipine. Polymeric films of nitrendipine were prepared by the film casting technique (glass ring) on mercury substrate. They were evaluated for physicochemical parameters, in vitro release and ex vivo permeation (heat separated human epidermis). Release of the drug from the films followed anomalous transport (0.5 < n < 1). Polymeric combination containing Eudragit RL 100:PVP K 30 in 4:6 ratio showed the best results. Maximum drug release and skin permeability coefficient in 48 h were 85.8 % and 0.0142 cm h-1, respectively, in formulation C3 (Eudragit RL 100: Plasdone S 630; 4:6) and 88.0 % and 0.0155 cm h-1, respectively, in formulation D3 (Eudragit RL 100: PVP K 30; 4:6). FTIR and TLC studies indicated no drug and polymer interaction.Cilj rada bio je razvoj transdermalnog sustava nitrendipina. Polimerni filmovi nitrendipina pripravljeni su metodom lijevanja (stakleni prsten) na podlozi od žive. Ispitivani su fizičkokemijski parametri, in vitro oslobađanje i ex vivo permeacija (toplinom odvojena humana epiderma). Oslobađanje lijeka iz filmova slijedilo je anomalni transport (0,5 < n < 1). Najbolji rezultati postignuti su kombinacijom polimera Eudragit RL 100 i PVP K 30 u omjeru 4:6. Maksimalno oslobađanje ljekovite tvari i najbolji koeficijent permeacije kroz kožu tijekom 48 h bio je 85,8 %, odnosno 0,0142 cm h1 za formulaciju C3 (Eudragit RL 100 : Plasdone S 630; 4:6) i 88,0 %, odnosno 0,0155 cm h1 za formulaciju D3 (Eudragit RL 100 : PVP K 30; 4:6). FTIR i TLC ukazuju na to da nema interakcije između ljekovite tvari i polimera

Malnutrition Awareness Among University Students From Mumbai, India, and Hannover, Germany

Malnutrition is the condition in which the body does not get the right amount of proteins, vitamins, or other nutrients.1 The global prevalence of malnutrition was reported as 13% in 2015.2 The subregion of South Asia is especially known as a critical area for severe wasted children aged <5 years.3 In India, 38.4% of children aged <3 years are stunted, and 46% are underweight.4 Malnutrition can lead to mortality as well as disabilities and long-term consequences such as cognitive disabilities, less economic productivity, or diseases

Oxidation characteristics of nickel based superalloys in steam

An improvement in the efficiency of land based gas turbines is sought by replacing air with steam for the internal cooling of hot gas path components. However, the degradation behavior and mechanisms associated with the interaction of superalloys with steam at high temperatures are unknown. This information is very crucial for the reliability as well as for useful life prediction of the gas turbine components. In this work, oxidation in steam has been studied for three nickel based superalloys commonly used in the gas turbines. These are IN 738, Inconel 617, and CMSX-4. The study was carried out at four different test temperatures in the range of 800 °C to 950 °C for times up to 1400 hours. The results indicated significantly different oxidation behavior in steam compared to air for all the alloys tested

Oxidation characteristics of Nickel based superalloys in steam

An improvement in the efficiency of land based gas turbines is sought by replacing air with steam for the internal cooling of hot gas path components. However, the degradation behavior and mechanisms associated with the interaction of superalloys with steam at high temperatures are unknown. This information is very crucial for the reliability as well as for useful life prediction of the gas turbine components. In this work, oxidation in steam has been studied for three nickel based superalloys commonly used in the gas turbines. These are IN 738, Inconel 617, and CMSX-4. The study was carried out at four different test temperatures in the range of 800°C to 950°C for times up to 1400 hours. The results indicated significantly different oxidation behavior in steam compared to air for all the alloys tested

Fluorescent Copper Probe Inhibiting Aβ1–16-Copper(II)-Catalyzed Intracellular Reactive Oxygen Species Production

A variety of fluorescent probes are proposed to monitor the intracellular copper content. So far, none of the probes have been evaluated for their potential to inhibit copper-associated intracellular oxidative stress. Herein, we studied the ability of a fluorescent copper probe, OBEP-CS1, to inhibit intracellular oxidative stress associated with an amyloid β (Aβ) peptide–copper complex. The data showed that OBEP-CS1 completely inhibits the copper-catalyzed oxidation as well as decarboxylation/deamination of Aβ1–16. Moreover, the cell imaging experiments confirmed that OBEP-CS1 can inhibit Aβ-Cu^II-catalyzed reactive oxygen species production in SH-SY5Y cells. We also demonstrated that Aβ1–16 peptide can bind intracellular copper and thereby exert oxidative stress

Quantification of brain phosphodiesterase 4 in rat with (R)-[11C]Rolipram-PET

Objective: Phosphodiesterase 4 (PDE4) catabolizes the second messenger 3', 5'-cyclic adenosine monophosphate and may play a critical role in brain diseases. Our aim was to quantity PDE4 in rats with positron emission tomography (PET). Methods: High (n = 6) and low specific activity (SA) (n = 2) higher affinity ((R)-[C-11]rolipram) and high SA lower affinity ((S)-[C-11]rolipram) (n = 2) enantiomers were intravenously administered to Sprague-Dawley rats. Brain data were acquired using the ATLAS PET scanner and reconstructed using, the 3D-ordered subset expectation maximization algorithm. Arterial samples were taken to measure unmetabolized [C-11]rolipram. Total distribution volumes (V'(T)) were calculated using a 1-tissue compartment (1C) and an unconstrained 2-tissue compartment (2C) model. Results: High SA R experiments showed later and greater brain uptake, and slower washout than low SA R and S experiments. In all regions and in all experiments, the 2C model gave significantly better fitting than the 1C model. The poor fitting by the latter caused underestimation of V'(T) by 19-31%. The 2C model identified V'(T) reasonably well with coefficients of variation less than 10%. V'(T) values by this model were 16.4-29.2 mL/cm(3) in high SA R, 2.9-3.5 in low SA R, and 3.1-3.7 in S experiments. Conclusions: Specific binding of (R)-[C-11]rolipram was accurately measured in living rats. In high SA R experiments. similar to 86% of V'(T) was specific binding. Distribution and changes of PDE4 in animal models can now be studied by measuring V'(T) of high SA (R)-[C-11]rolipram.</p