Robust vibration invariant SSHI rectifier circuit for piezoelectric device

Analog Integrated Circuits and Signal Processing - Rectifier is the most critical block of the power conditioning circuit designed for the Piezoelectric Energy Harvester (PZEH). Maintaining high...     

Superprotonic Conductivity of MOFs and Other Crystalline Platforms Beyond 10−1 S cm−1

The proton-exchange membrane (PEM) is a fundamental module of proton-exchange membrane fuel cells (PEMFCs), permitting proton passage and thus governing the overall performance of PEMFCs. Till now, Nafion has been the extensively used marketable PEM material due to its high protonic conductivity of 10⁻²–10⁻¹ S cm⁻¹ under high relative humidity and 80–85 °C. On the other hand, crystalline materials such as metal-organic frameworks (MOFs), coordination polymers (CPs), covalent organic frameworks (COFs), hydrogen-bonded organic framework (HOFs), metalo hydrogen-bonded organic framework (MHOFs), and polyoxometalates (POMs) are emerging as potential PEM materials, where crystallinity has paved the way to study the conduction pathway and associated mechanisms to understand structure-function relationships. However, to date, ultrahigh superprotonic conductivity to the level of 10⁻¹ S cm⁻¹, close to Nafion, is relatively scarce for the crystalline proton conductors. In this review, the discussion is focused on materials that demonstrate a conductivity order of 10⁻¹ S cm⁻¹ and higher for those individual crystalline platforms (to be on the equal footing and superior to nafion, respectively) based on their synthesis approach while highlighting the design norms and key features for attaining such ultrahigh conductivity. While a critical analysis is made, the key issues and future prospects are also addressed.     

A comparative study on the effect of packaging material and storage environment on shelf life of fresh bell-pepper

The effect of packaging materials [low density polyethylene (LDPE), polypropylene (PP)] and storage environment [modified atmospheric packaging (MAP)] on shelf life enhancement of bell pepper in terms of quality attributes such as physiological weight loss, ascorbic acid, texture, surface colour and subjective quality analysis have been studied at ambient and refrigerated condition. Different packaging techniques used for the experiment were MAP with LDPE, MAP with PP, MAP in perforated LDPE films, MAP in perforated PP films, shrink packaging with bi-axially oriented PP (BOPP) film and vacuum packaging with PP film. The in-pack bell pepper created a suitable headspace environment with low O₂ and high CO₂ concentrations, which resulted in a better retention of freshness of the vegetables and its marketability. Shrink packaging with BOPP film could not yield better result under ambient storage because of high water vapor transmission rate of the film and consequently loss of turgidity of the vegetables. Among different packaging techniques and storage conditions, MAP with PP film in refrigerated condition was found to be the best followed by vacuum pack with PP film in refrigerated condition and could be used to store for 20 days for bell pepper with maintenance of texture, colour, ascorbic acid and marketability. It is also inferred that under ambient conditions, bell pepper could be stored for 4 days using ventilated LDPE and PP as MAP storage. Further studies are needed to evaluate the sensory aspects, as well as to microbiological evaluation to characterize the fresh bell pepper during storage.     

Fabrication of comb structure with vertical sidewalls in Si (110) substrate by wet etching in boiling KOH solution

Microsystem Technologies - This paper discusses about the fabrication of comb-structure with vertical sidewall profile by wet chemical etching of Si (110) substrate in boiling KOH solution. Etch...     

Design of laser micromachined single crystal 6H–SiC diaphragms for high-temperature micro-electro-mechanical-system pressure sensors

A 248-nm, 23-ns pulsed excimer laser was used to micromachine 50 μm thick diaphragms in 6H–SiC wafers. The diaphragms were then subjected to high-pressure (0.7–7 MPa) and high temperature (500 K) tests to obtain the pressure-deflection curves. A finite element model was used to predict the stresses and displacements as a function of temperature and pressure. Model data is in good agreement with experiments. The stresses, strains and displacements were determined in order to facilitate the design of high-temperature micro-electro-mechanical-system pressure sensors.     

Separation and Recovery of Uranium from Wastewater Using Sorbent Functionalized with Hydroxamic Acid

A newly developed hydroxamic acids functionalized acrylic based solid phase sorbent, named as poly-acryl hydroxamic acid (PHOA) is used as an extractant for the recovery of uranium from nuclear waste solution. Various parameters such as sorbent solubility in different medium, effect of various cations on U(VI) sorption, desorption performance of different eluents with respect to U(VI) sorption has been investigated in detail. U(VI) sorption behaviors of the sorbent were studied in different concentration of competitive ions such as Mg²⁺, Fe³⁺, and NO₃^? and it was found that the sorbent was capable of removing the U(VI) efficiently in the presence of high concentration of these ions.     

Chemistry and antioxidant activity of essential oil and oleoresins of black caraway (Carum bulbocastanum) fruits: Part 69

BACKGROUND: The present study describes the chemical analysis of the essential oil and oleoresins from caraway, which have been studied by using GC–MS. The paper also explains the importance of the extracted oil and oleoresins in the antioxidant activities of target plant species. RESULTS: GC–MS analysis of caraway essential oil showed 51 compounds representing about 96.6% of the total weight. The major components were dillapiole (44.6%), germacrene‐β (14.1%), nothoapiole (8.3%), and β‐selinene (6.8%), along with many other components in minor amounts. Major components in ethyl acetate and iso‐octane oleoresins are dillapiole, nothoapiole and germacrene‐β, whereas in ethanol oleoresin contains dillapiole (25%), sitosterol (21.3%) stigmasterol (9.5%) and nothoapiole (8.1%). The antioxidant activity was evaluated by various antioxidant assays such as peroxide, thiobarbituric acid and p‐anisidine values. These experiments were further supported by other complementary antioxidant assays such as ferric thiocyanate method in linoleic acid system, reducing power, and scavenging effects on 1,1′‐diphenyl‐2‐picrylhydrazyl (DPPH). Both the caraway volatile oil and its oleoresins showed strong antioxidant activity in comparison with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). CONCLUSION: This study provides additional information about the chemistry and antioxidant activity of caraway. Hence, caraway may be used as natural food preservatives. Copyright © 2009 Society of Chemical Industry