Piezoelectric bimorph MEMS speakers

One of the key requirements for MEMS speakers is to increase the sound pressure level(SPL)while keeping the size as small as possible.In this paper we present a MEMS speaker based on piezoelectric bimorph cantilevers that produces a higher SPL than conventional unimorph cantilever speakers.The active diaphragm size is 1.4×1.4 mm^(2).The bimorph cantilevers are connected in parallel to make full use of the actuation voltage.At 1 kHz,the measured SPL reached 73 dB and the peak SPL reached 102 dB at the resonance frequency of 10 kHz in a 711 ear simulator under a driving voltage of 10 V_(rms).The total harmonic distortion of the MEMS speaker was less than 3%in the range from 100 Hz to 20 kHz.Although the absolute SPL was not the highest,this work provides a better SPL for all piezoelectric MEMS speakers.

A Comparative Kinetic Study on the Efficacious Permanganate Oxidation of Fluorenes in Perchloric and Sulfuric Acid Media

Oxidation kinetics of fluorene (Fl) and its halogenated derivatives, namely, 2,7-dichlorofluorene (Fl-Cl), 2,7-dibromofluorene (Fl-Br) and 2,7-diiodofluorene (Fl-I), by permanganate ion in both perchloric and sulfuric acid media have been investigated using conventional spectrophotometric technique. In both acidic media, the reactions manifested first order kineticsin [permanganate] and less than unit order each in [reductants] and [acid]. Increasing ionic strength had no effect on the oxidation rates. Oxidation rates of fluorenes in perchloric acid were higher than those in sulfuric acid and the order of the oxidation rates was: Fl > Fl-I > Fl-Br > Fl-Cl. Final oxidation products were identified by GC/MS and FT-IR analyses in all cases as 9H-fluorenone derivatives. Reaction constants as well as activation parameters of the second order rate constants were also evaluated.

The Genetic Variant c.553G>T in the Lipoprotein A5 Effects on Lipid Profile Parameters Levels

Abnormal levels of plasma lipid have been linked to atherosclerosis, strokes and heart conditions. Variations in high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol levels are considered as risk factors for coronary artery disease (CAD). Furthermore, triglycerides are a leading cause of cardiovascular disease. Therefore, measurement of plasma lipid levels is an important mortality predictor. Several factors were associated with irregularity in plasma lipids such as genetic alterations. Recent researches have linked single nucleotides polymorphism (SNP) in ApoA5 gene with these deviations. In this study, we reported the effects of the genetic variant c.553G>T in ApoA5 on the levels of plasma lipids. To explore these effects, a case-control study including 280 male and female subjects (44 of them were assigned as CAD cases while the remaining subjects were categorized as control) was established. All patients in the study were recruited from the western region in KSA. The results have detected minor variations in LDL, HDL and cholesterol levels between CAD patients carrying T allele and CAD patients carrying the WT allele. However, there were no significant effects due to these variations. TG levels in the wild type carriers reached up to 291 mg/dl while T allele carriers, the cases, presented lower levels of TG (170 mg/dl and 71 mg/dl). Although, T allele showed no effects on plasma lipids with the exception of TG levels. We suggest by this study that T allele in this SNP might be considered as a valuable tool in the diagnosis of CAD.

Whole Exome Sequencing: Novel Genetic Polymorphisms in Saudi Arabian Attention Deficit Hyperactivity Disorder (ADHD) Children

Background: Attention-deficit hyperactivity disorder (ADHD) is a widespread and debilitating disorder with relatively high prevalence in Saudi Arabia. Neuropsychological and radiological investigations have revealed that there are some differences in the components of the brain regions in children with and without ADHD. In this study we have performed whole exome sequencing (WES) in four non-familial cases of ADHD from Makkah Region to identify the genetic polymorphisms associated with the disease in our Saudi population. Methods: Exome sequencing was carried out using Ion Proton with AmpliSeq Exome library methods, and the data were analysed by Ion Reporter 5.6 software. Results: A total of 33 variants were identified from 222 genes selected from the GWAS catalogue for ADHD associated genes. However, the SNPs we identified in these genes were not reported to be associated with ADHD in previous studies. We have identified 2 novel missense variants;one in c.3451G > T;p. (Ala1151Ser) in ITGA1 gene and another is c.988G > A;p. (Ala330Thr) in SPATA13 genes. The variants rs928661, rs11150370 and rs386792899 were the only three variants that appeared on all the 4 patients studied. Six missense variants, rs16841277, rs2228209, rs2230283, rs3741883, rs1716 and rs2272606, were found in 3 different patients, respectively. However, the three documented variants are rs13166360 with bipolar disorder, rs920829 with neuropathic pain, and rs6558702 with schizophrenia. Conclusion: We have identified 2 novel variants in ADHD children. SIFT score of all variants indicates that these substitutions have damaging effects on the protein function. Further screening studies are recommended for confirmation.

Performance Analysis on a Dual External Cavity Tunable Laser ECTL Source

This paper presents the diffraction effects on the performance of a dual external cavity tunable laser source, whose external cavities are constructed by micro electro mechanical systems (MEMS). One of the main problems in these structures is the optical diffraction as the emitting surface of the laser diode is usually quite limited in the transverse directions. The emitted beam diffracts rapidly in the air and only a small amount of light is coupled back to the source that usually limits the tuning range of the source. Device characteristics such as tuning range, wavelength shift and sensitivity are evaluated. New expression is used and multiple reflections inside external cavities are considered. The simulation results have shown that single external cavity has limited tuning range. It is shown that multiple reflections have significant effect in our model. To get a better engineering for the dual ECTL dimensions, diffraction effects must be taken into account.

Polymeric biomaterial hydrogels. I. Behavior of some ionotropic cross-linked metal-alginate hydrogels especially copper-alginate membranes in some organic solvents and buffer solutions

The change in rheological and mechanical properties for some ionotropic cross-linked metal-alginate hydrogel complexes in particularly copper-alginate membranes in the presence of some organic solvents (benzene, toluene, xylene, carbon tetrachloride, ace-tone, chloroform, dichloroethane, isobutyl alcohol and ethyl alcohol) or buffer solutions (acetates, borates and universal buffers) have been investigated. The experimental results showed a remarkable tendency of the studied hydrogels for shrinking in polar solvents, whereas no influence was observed for the hydrogels in non-polar solvents. On the other hand, the gels were found to swell or shrink in the buffer solutions depending on the pH of the buffer used. The swelling extent for hydrogel spheres was found to decrease in the order Cu > Ba ≈ Ca > Zn > Pb-alginates in universal buffers of pH = 5.33. The factors affected this behavior have been examined and discussed.