Geometrical Optimization of Resonant Cantilevers Vibrating in In-Plane Bending Modes

The influence of the beam geometry on the quality factor and resonance frequency of resonant silicon cantilever beams vibrating in their fundamental in-plane flexural mode has been investigated in air and water. Compared to cantilevers vibrating in their out-of-plane flexural mode, utilizing the in plane mode results in reduced damping and reduced mass loading by the surrounding fluid. Quality factors as high as 4,300 in air and 67 in water have been measured for cantilevers with a 12 μm thick silicon layer. This is in comparison to Q factors up to 1,500 in air and up to 20 in water for cantilevers vibrating in their fundamental out-of-plane bending mode. Based on the experimental data, design guidelines are established for beam dimensions that ensure maximal Q-factors and minimal mass loading by the surrounding fluid

Liquid-Phase Chemical Sensing Using Lateral Mode Resonant Cantilevers

Liquid-phase operation of resonant cantilevers vibrating in an out-of-plane flexural mode has to date been limited by the considerable fluid damping and the resulting low quality factors (Q factors). To reduce fluid damping in liquids and to improve the detection limit for liquid-phase sensing applications, resonant cantilever transducers vibrating in their in-plane rather than their out-of-plane flexural resonant mode have been fabricated and shown to have Q factors up to 67 in water (up to 4300 in air). In the present work, resonant cantilevers, thermally excited in an in-plane flexural mode, are investigated and applied as sensors for volatile organic compounds in water. The cantilevers are fabricated using a complementary metal oxide semiconductor (CMOS) compatible fabrication process based on bulk micromachining. The devices were coated with chemically sensitive polymers allowing for analyte sorption into the polymer. Poly(isobutylene) (PIB) and poly(ethylene-co-propylene) (EPCO) were investigated as sensitive layers with seven different analytes screened with PIB and 12 analytes tested with EPCO. Analyte concentrations in the range of 1−100 ppm have been measured in the present experiments, and detection limits in the parts per billion concentration range have been estimated for the polymer-coated cantilevers exposed to volatile organics in water. These results demonstrate significantly improved sensing properties in liquids and indicate the potential of cantilever-type mass-sensitive chemical sensors operating in their in-plane rather than out-of-plane flexural modes

In-Plane Vibration of Hammerhead Resonators for Chemical Sensing Applications

Thermally excited and piezoresistively detected in-plane cantilever resonators have been previously demonstrated for gas- and liquid-phase chemical and biosensing applications. In this work, the hammerhead resonator geometry, consisting of a cantilever beam supporting a wider semicircular “head”, vibrating in an in-plane vibration mode, is shown to be particularly effective for gas-phase sensing with estimated limits of detection in the sub-ppm range for volatile organic compounds. This paper discusses the hammerhead resonator design and the particular advantages of the hammerhead geometry, while also presenting mechanical characterization, optical characterization, and chemical sensing results. These data highlight the distinct advantages of the hammerhead geometry over other cantilever designs

Chemical composition and biological activities of Valeriana dioscoridis SM. Roots

Zika, dengue, and Yellow fever are transmitted primarily by Aedes aegypti mosquitoes. Investigations to find more natural but highly effective pesticidal agents against Ae. aegypti have increased in the last few years. Plant-based compounds have been the source of several current pesticides and have provided models for creation of synthetic derivatives like the pyrethroids. Plants continue to be a rich source for potential new active ingredients. The aim of this study is to increase knowledge on V. dioscoridis and to present the results of the cytotoxic and insecticidal activities of various extracts of its roots and volatile compound compositions of roots. The hexane and chloroform extracts, HM1 and CM1 respectively, exhibited cytotoxicity with IC50 values of 128.4 and 86.93 µg/mL against the HepG2 cell line. Because CM1 had higher cytotoxicity across the studied concentration range, it was also tested against the HUVEC cell line. Extracts HM1 and CM1 were also tested for their insecticidal activities. CM1 was found to be the more active (mortality (%) =96.7% ± 5.8 at 5μg/mosquito), consistent with its cytotoxic activity. Since these active extracts were nonpolar, the chemical composition of the volatile compounds of the roots were analyzed by GC-MS analysis. About 87.7% of the essential oil were characterized. The major compound was ß-eudesmol (9.2%), following by camphene (8.9%), bornyl acetate (8.2%) and maaliol (7.6%). This is the first study on the HepG2 and HUVEC cytotoxicity and insecticidal activity of V. dioscoridis. Further studies on the potential of this plant to define the spectrum of activity and examine potential therapeutic agents is warranted

A patient-based study on the adherence of physicians to guidelines for the management of type 2 diabetes in Turkey.

Aims: To evaluate physicians' adherence to guidelines by Diabetes Study Group of The Society of Endocrinology and Metabolism of Turkey (SEMT)

Impact of Obesity on the Metabolic Control of Type 2 Diabetes: Results of the Turkish Nationwide Survey of Glycemic and Other Metabolic Parameters of Patients with Diabetes Mellitus (TEMD Obesity Study)

Background: Obesity is the main obstacle for metabolic control in patients with type 2 diabetes. Turkey has the highest prevalence of obesity and type 2 diabetes in Europe. The effect of obesity on the metabolic control, and the macro-and microvascular complications of patients are not apparent. Objectives: This nationwide survey aimed to investigate the prevalence of overweight and obesity among patients with type 2 diabetes and to search for the impact of obesity on the metabolic control of these patients. We also investigated the independent associates of obesity in patients with type 2 diabetes. Methods: We consecutively enrolled patients who were under follow-up for at least 1 year in 69 tertiary healthcare units in 37 cities. The demographic, anthropometric, and clinical data including medications were recorded. Patients were excluded if they were pregnant, younger than 18 years, had decompensated liver disease, psychiatric disorders interfering with cognition or compliance, had bariatric surgery, or were undergoing renal replacement therapy. Results: Only 10% of patients with type 2 diabetes (n = 4,648) had normal body mass indexes (BMI), while the others were affected by overweight (31%) or obesity (59%). Women had a significantly higher prevalence of obesity (53.4 vs. 40%) and severe obesity (16.6 vs. 3.3%). Significant associations were present between high BMI levels and lower education levels, intake of insulin, antihypertensives and statins, poor metabolic control, or the presence of microvascular complications. Age, gender, level of education, smoking, and physical inactivity were the independent associates of obesity in patients with type 2 diabetes. Conclusion: The TEMD Obesity Study shows that obesity is a major determinant of the poor metabolic control in patients with type 2 diabetes. These results underline the importance of prevention and management of obesity to improve health care in patients with type 2 diabetes. Also, the results point out the independent sociodemographic and clinical associates of obesity, which should be the prior targets to overcome, in the national fight with obesity. (c) 2019 The Author(s) Published by S. Karger AG, Base

Turkish nationwide survEy of glycemic and other Metabolic parameters of patients with Diabetes mellitus (TEMD study)

Aims: Turkey has the highest prevalence of diabetes in Europe. It is therefore essential to know the overall cardiovascular risk and reveal the predictors of metabolic control in Turkish adults with diabetes mellitus