Assessment of a practical technique for active control of sound using microphone and speaker

AbstractIn this analytical study, it has been desired to develop a practical and simple control mechanism to control, at a given point and its neighborhood, the sound arriving from a distant source, assuming that a primary pure-tone sound pressure is propagated from a relatively far distance. The control model consists of a microphone as a sensor for measuring the sound pressure and a loud speaker for applying the control force. Corresponding equations have been developed to determine an optimum control force, and afterwards a parametric study on the factors affecting the control results has been performed. The results show that the control system can significantly reduce low frequency sound pressure in the region near the target point. The results also demonstrate less effectiveness in controlling high frequency sound pressures. Moreover, the larger the distance of the loudspeaker to the given controlled point is, the wider the controlled area will be. Also, it was found that though the distance between the sensor and the actuator does not have any effect on the size of the area which can be controlled, such distance is of greatest importance in that the available time to control increases directly by increasing the distance

Effect of hydroalcoholic extract of Matricaria chamomilla on passive avoidance memory and pain induced by global cerebral ischemia in Wistar rat

زمینه و هدف : ایسکمی مغزی و خونرسانی مجدد علت اصلی ناتوانی جدی و طولانی مدت در جهان است. هدف از مطالعه حاضر بررسی اثر عصاره هیدروالکلی بابونه بر اختلالات حافظه و درد ناشی از ایسکمی بود. روش بررسی: گل‌های خشک بابونه (Matricaria chamomilla) از عطاری تهیه شده و توسط الکل 70 درصد عصاره گیری شد. حیوانات به صورت تصادفی به 6 گروه 7 تایی تقسیم شدند. گروه کنترل فقط نرمال سالین دریافت کردند، گروه ایسکمی تحت ایسکمی قرار گرفته و نرمال سالین دریافت کردند، گروه شاهد(sham): تحت جراحی قرار گرفتند بدون اینکه شریان‌های کاروتید آن‌ها بسته شود. گروه‌های درمانی با عصاره تحت ایسکمی قرار گرفته و عصاره بابونه را به صورت داخل صفاقی در دوز 50، 100 و 200 میلی‌گرم بر کیلوگرم وزن بدن دریافت کردند. تست رفتاری توسط شاتل باکس و تست ضد درد توسط تست تیل فیلیک انجام شد. یافته ها : عصاره بابونه در غلظت‌های 50، 100 و 200 میلی‌گرم بر کیلوگرم حافظه احترازی غیرفعال موش‌های صحرایی تحت ایسکمی را به طور معنی‌دار افزایش داد. علاوه بر این عصاره بابونه زمان تأخیر ظهور رفلکس دردناک دم را در تست تیل فلیک به طور معنی‌داری افزایش داد و غلظت 50 میلی‌گرم بر کیلوگرم عصاره اثر بیشتری نسبت به غلظت‌های بالاتر آن نشان داد. بحث و نتیجه گیری: نتایج مطالعه حاضر حاکی از اثرات حفاظتی عصاره بابونه در برابر اختلال حافظه احترازی و درد ایجاد شده در اثر ایسکمی بود که احتمالا به دلیل اثرات آنتی‌اکسیدانی و ضدالتهابی عصاره گیاه می‌باش

Robust prescribed trajectory tracking control of a robot manipulator using adaptive finite-time sliding mode and extreme learning machine method

This study aims to provide a robust trajectory tracking controller which guarantees the prescribed performance of a robot manipulator, both in transient and steady-state modes, experiencing parametric uncertainties. The main core of the controller is designed based on the adaptive finite-time sliding mode control (SMC) and extreme learning machine (ELM) methods to collectively estimate the parametric model uncertainties and enhance the quality of tracking performance. Accordingly, the global estimation with a fast convergence rate is achieved while the tracking error and the impact of chattering on the control input are mitigated significantly. Following the control design, the stability of the overall control system along with the finite-time convergence rate is proved, and the effectiveness of the proposed method is investigated via extensive simulation studies. The results of simulations confirm that the prescribed transient and steady-state performances are obtained with enough accuracy, fast convergence rate, robustness, and smooth control input which are all required for practical implementation and applications

Antidiabetic potential of salvianolic acid B in multiple low-dose streptozotocin-induced diabetes

Context: Salvianolic acids are the most abundant water-soluble compounds extracted from the herb Salvia miltiorrhiza L. (Lamiaceae) with antioxidant and protective effects. Objective: This study evaluates the antidiabetic effect of salvianolic acid B (Sal B) in multiple low-dose streptozotocin (MLDS)-induced diabetes in rat. Materials and methods: Rats were divided into control, Sal B40-treated control, diabetic, Sal B20-, and Sal B40-treated diabetic groups. Sal B was daily administered at doses of 20 or 40 mg/kg (i.p.), started on third day post-STZ injection for 3 weeks. Serum glucose and insulin level and some oxidative stress markers in pancreas were measured in addition to the oral glucose tolerance test (OGTT), histological assessment, and apoptosis determination. Results: After 3 weeks, treatment of diabetic rats with Sal B20 and Sal B40 caused a significant decrease of the serum glucose (p<0.05-0.01) and improvement of OGTT. Meanwhile, serum insulin was significantly higher in Sal B20- and Sal B40-treated diabetics (p<0.01) and treatment of diabetics with Sal B40 significantly lowered malondialdehyde (MDA) (p<0.05), raised glutathione (GSH) (p<0.05), and activity of catalase (p<0.01) with no significant change of nitrite. Furthermore, the number of pancreatic islets (p<0.05) and their area (p<0.01) was significantly higher and apoptosis reactivity was significantly lower (p<0.05) in the Sal B40-treated diabetic group versus diabetics. Discussion and conclusion: Three-week treatment of diabetic rats with Sal B exhibited antidiabetic activity which is partly exerted via attenuation of oxidative stress and apoptosis and augmentation of antioxidant system. © 2015 Informa Healthcare USA, Inc

Experimental and numerical study of elasto-inertial focusing in straight channels.

Elasto-inertial microfluidics has drawn significant attention in recent years due to its enhanced capabilities compared to pure inertial systems in control of small microparticles. Previous investigations have focused mainly on the applications of elasto-inertial sorting, rather than studying its fundamentals. This is because of the complexity of simulation and analysis, due to the presence of viscoelastic force. There have been some investigative efforts on the mechanisms of elasto-inertial focusing in straight channels; however, these studies were limited to simple rectangular channels and neglected the effects of geometry and flow rates on focusing positions. Herein, for the first time, we experimentally and numerically explore the effects of elasticity accompanying channel cross-sectional geometry and sample flow rates on the focusing phenomenon in elasto-inertial systems. The results reveal that increasing the aspect ratio weakens the elastic force more than inertial force, causing a transition from one focusing position to two. In addition, they show that increasing the angle of a channel corner causes the elastic force to push the particles more efficiently toward the center over a larger area of the channel cross section. Following on from this, we proposed a new complex straight channel which demonstrates a tighter focusing band compared to other channel geometries. Finally, we focused Saccharomyces cerevisiae cells (3-5 μm) in the complex channel to showcase its capability in focusing small-size particles. We believe that this research work improves the understanding of focusing mechanisms in viscoelastic solutions and provides useful insights into the design of elasto-inertial microfluidic devices

Development of a Biomimetic Semicircular Canal with MEMS Sensors to Restore Balance

© 2001-2012 IEEE. A third of adults over the age of 50 suffer from chronic impairment of balance, posture, and/or gaze stability due to partial or complete impairment of the sensory cells in the inner ear responsible for these functions. The consequences of impaired balance organ can be dizziness, social withdrawal, and acceleration of the further functional decline. Despite the significant progress in biomedical sensing technologies, current artificial vestibular systems fail to function in practical situations and in very low frequencies. Herein, we introduced a novel biomechanical device that closely mimics the human vestibular system. A microelectromechanical systems (MEMS) flow sensor was first developed to mimic the vestibular haircell sensors. The sensor was then embedded into a three-dimensional (3D) printed semicircular canal and tested at various angular accelerations in the frequency range from 0.5Hz to 1.5Hz. The miniaturized device embedded into a 3D printed model will respond to mechanical deflections and essentially restore the sense of balance in patients with vestibular dysfunctions. The experimental and simulation studies of semicircular canal presented in this work will pave the way for the development of balance sensory system, which could lead to the design of a low-cost and commercially viable medical device with significant health benefits and economic potential

Fibre Optic pH Sensor Using Optimized Layer-by-Layer Coating Approach

In this study the design and characterization of a high resolution wavelength dependent pH optical sensor fabricated using the layer-by-layer technique was undertaken. In this approach, brilliant yellow (BY) as a pH indicator and poly (allylamine hydrochloride) [PAH] as a cross-linker have been deposited on an uncladded silica fibre. A number of key parameters, such as the number of bilayers, the concentration of the BY solution and the shape of the fibre, as well as its core diameter have been varied with a view to optimizing the design and performance of the pH sensor. The results obtained from a series of evaluations show that the sensitivity was enhanced by reducing the concentration of the indicator solution used and by designing a U-bend configuration sensor probe with a sharply bent fibre. However, when making an overall comparison, the straight (unbent) fibre probe resulted in a more sensitive probe when compared to the use of a high radius bend. Further, utilizing a small core diameter of the fibre allows a wide pH range to be measured and with high sensitivity. Additionally, the performance was shown to be improved for measurements over a narrower range of pH, by using a fibre with a larger core diameter. Considering the effect of the number of layers, work carried out has shown that probes with 5-6 bilayers presented the best performance. The sensitivity has been shown to diminish when more than 6 layers were used and the sensing range shifts towards higher pH values. When monitored, the value of pKa (the dissociation constant) of the thin film showed the smallest change of any of the design factors considered. In summary, using a larger core diameter, employing a larger curve radius, a higher number of bilayers, a higher concentration of the indicator solution and applying PAH as an outer layer, all cause a higher pKa value and consequently the probe sensitivity moves towards alkaline region

3D Printing of Inertial Microfluidic Devices.

Inertial microfluidics has been broadly investigated, resulting in the development of various applications, mainly for particle or cell separation. Lateral migrations of these particles within a microchannel strictly depend on the channel design and its cross-section. Nonetheless, the fabrication of these microchannels is a continuous challenging issue for the microfluidic community, where the most studied channel cross-sections are limited to only rectangular and more recently trapezoidal microchannels. As a result, a huge amount of potential remains intact for other geometries with cross-sections difficult to fabricate with standard microfabrication techniques. In this study, by leveraging on benefits of additive manufacturing, we have proposed a new method for the fabrication of inertial microfluidic devices. In our proposed workflow, parts are first printed via a high-resolution DLP/SLA 3D printer and then bonded to a transparent PMMA sheet using a double-coated pressure-sensitive adhesive tape. Using this method, we have fabricated and tested a plethora of existing inertial microfluidic devices, whether in a single or multiplexed manner, such as straight, spiral, serpentine, curvilinear, and contraction-expansion arrays. Our characterizations using both particles and cells revealed that the produced chips could withstand a pressure up to 150 psi with minimum interference of the tape to the total functionality of the device and viability of cells. As a showcase of the versatility of our method, we have proposed a new spiral microchannel with right-angled triangular cross-section which is technically impossible to fabricate using the standard lithography. We are of the opinion that the method proposed in this study will open the door for more complex geometries with the bespoke passive internal flow. Furthermore, the proposed fabrication workflow can be adopted at the production level, enabling large-scale manufacturing of inertial microfluidic devices

Fabrication of unconventional inertial microfluidic channels using wax 3D printing.

Inertial microfluidics has emerged over the past decade as a powerful tool to accurately control cells and microparticles for diverse biological and medical applications. Many approaches have been proposed to date in order to increase the efficiency and accuracy of inertial microfluidic systems. However, the effects of channel cross-section and solution properties (Newtonian or non-Newtonian) have not been fully explored, primarily due to limitations in current microfabrication methods. In this study, we overcome many of these limitations using wax 3D printing technology and soft lithography through a novel workflow, which eliminates the need for the use of silicon lithography and polydimethylsiloxane (PDMS) bonding. We have shown that by adding dummy structures to reinforce the main channels, optimizing the gap between the dummy and main structures, and dissolving the support wax on a PDMS slab to minimize the additional handling steps, one can make various non-conventional microchannels. These substantially improve upon previous wax printed microfluidic devices where the working area falls into the realm of macrofluidics rather than microfluidics. Results revealed a surface roughness of 1.75 μm for the printed channels, which does not affect the performance of inertial microfluidic devices used in this study. Channels with complex cross-sections were fabricated and then analyzed to investigate the effects of viscoelasticity and superposition on the lateral migration of the particles. Finally, as a proof of concept, microcarriers were separated from human mesenchymal stem cells using an optimized channel with maximum cell-holding capacity, demonstrating the suitability of these microchannels in the bioprocessing industry

Cloning, expression and purification of escherichia coli modified phytase

Introduction: Phytases are the class of phosphatases, which are capable of hydrolyzing phytic acid. Phytases with the phytate degradation are able to reduce or eliminate the harmful effects of phytate. Acidic and thermal stable phytase with high yield and purity by a relatively inexpensive system had extensive application. So, in this study, by modification in enzyme sequence, recombinant phytase production with the shorter length and high expression level was assessed. Materials and Methods: The phytase gene sequence was obtained from the NCBI database. After bioinformatics studies and doing the noted modification for increasing protein expression, gene proliferation was done by using PCR. E. coli BL21 (DE3) was used to express the protein. Protein purification was performed by Ni-NTA kit and finally, enzyme activity was assessed. Results: Phytase was successfully expressed and purified. Enzyme activity assay showed a significant activity. Conclusion: Produced recombinant phytase had high activity in spite of eliminating parts of the enzyme. © 2017, Semnan University of Medical Sciences. All rights reserved