Microlenses immersed in nematic liquid crystal with electrically controllable focal length

A microlens immersed in a nematic liquid crystal cell has been constructed with avariable focal length which can be controlled by applying an analogue voltage to thenematic liquid crystal. The focal length is -910 ± 30 ? m with no electric field appliedand with an applied field the focal length can be varied from 380 ± 50 to 560 ± 20 ? malthough at present the lens performance is limited by aberrations. A microlens immersed in a nematic liquid crystal cell has been constructed with avariable focal length which can be controlled by applying an analogue voltage to thenematic liquid crystal. The focal length is -910 ± 30 ? m with no electric field appliedand with an applied field the focal length can be varied from 380 ± 50 to 560 ± 20 ? malthough at present the lens performance is limited by aberrations. 12 May 199

Phase-Boundary of a Cubic Superconducting Circuit in a Magnetic-Field of Arbitrary Magnitude and Direction

Journals published by the American Physical Society can be found at http://journals.aps.org/An exact analytic expression for the mean-field phase boundary T(c)(H) of a cubic superconducting circuit in an arbitrary external-magnetic-field vector H is derived. The phase boundary of this circuit is shown to depend in a complex and sensitive way on both the magnitude and the direction of the magnetic field. Some practical applications of these properties are also suggested

A Microcantilever-based Gas Flow Sensor for Flow Rate and Direction Detection

The purpose of this paper is to apply characteristics of residual stress that causes cantilever beams to bend for manufacturing a micro-structured gas flow sensor. This study uses a silicon wafer deposited silicon nitride layers, reassembled the gas flow sensor with four cantilever beams that perpendicular to each other and manufactured piezoresistive structure on each micro-cantilever by MEMS technologies, respectively. When the cantilever beams are formed after etching the silicon wafer, it bends up a little due to the released residual stress induced in the previous fabrication process. As air flows through the sensor upstream and downstream beam deformation was made, thus the airflow direction can be determined through comparing the resistance variation between different cantilever beams. The flow rate can also be measured by calculating the total resistance variations on the four cantilevers.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838

Simple room-temperature preparation of high-yield large-area graphene oxide

Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer’s method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm2, respectively. The simplified Hummer’s method provides a facile approach for the preparation of large-area GO

Fabrication and characterization of graphene hydrogel via hydrothermal approach as a scaffold for preliminary study of cell growth

BACKGROUND: Three-dimensional assembly of graphene hydrogel is rapidly attracting the interest of researchers because of its wide range of applications in energy storage, electronics, electrochemistry, and waste water treatment. Information on the use of graphene hydrogel for biological purposes is lacking, so we conducted a preliminary study to determine the suitability of graphene hydrogel as a substrate for cell growth, which could potentially be used as building blocks for biomolecules and tissue engineering applications. METHODS: A three-dimensional structure of graphene hydrogel was prepared via a simple hydrothermal method using two-dimensional large-area graphene oxide nanosheets as a precursor. RESULTS: The concentration and lateral size of the graphene oxide nanosheets influenced the structure of the hydrogel. With larger-area graphene oxide nanosheets, the graphene hydrogel could be formed at a lower concentration. X-ray diffraction patterns revealed that the oxide functional groups on the graphene oxide nanosheets were reduced after hydrothermal treatment. The three-dimensional graphene hydrogel matrix was used as a scaffold for proliferation of a MG63 cell line. CONCLUSION: Guided filopodia protrusions of MG63 on the hydrogel were observed on the third day of cell culture, demonstrating compatibility of the graphene hydrogel structure for bioapplications

Salt content of instant noodles in Malaysia: a cross-sectional study

Objective To determine the salt content in instant noodles sold in Malaysia. Study design A cross-sectional survey was done involving 707 different flavours and packaging of instant noodles sold in six hypermarkets and retailer chains in Malaysia and the corresponding brand's official websites in 2017. Methods The salt content (gram per serving and per 100 g) was collected from the product packaging and corresponding brand's official website. Results Of the 707 different packaging and flavours of instant noodles, only 62.1% (n=439) provided the salt content in their food label. The mean (±SD) salt per 100 g of instant noodles was 4.3±1.5 g and is nearly four times higher than the salt content of food classified in Malaysia as a high salt content (>1.2 g salt per 100 g). The salt content for instant noodle per packaging ranged from 0.7 to 8.5 g. 61.7% of the instant noodles exceeded the Pacific Salt Reduction Target, 11.8% exceeded the WHO recommended daily salt intake of <5.0 per day and 5.50% exceeded Malaysia Salt Action Target. 98% of instant noodles will be considered as high salt food according to the Malaysia Guidelines. The probability of the instant noodles without mixed flavour (n=324) exceeding the Pacific Salt Reduction Target was tested on univariate and multivariate analysis. Instant noodles with soup, Tom Yam flavour, pork flavour and other flavours were found to be predictors of instant noodles with the tendency to exceed Pacific Salt Reduction Target when compared with instant noodles without mixed flavours (p<0.05). Conclusion Only 62% of instant noodles displayed the salt content on their food label. Salt content in instant noodles is very high, with 90% exceeding the daily salt intake recommended by WHO. Prompt action from regulatory and health authorities is needed to reduce the salt content in instant noodles. © Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ

Gasification reactor engineering approach to understanding the formation of biochar properties

Operational reactor temperatures (spanning the reduction zone), pressure, and product gas composition measurements from a downdraft gasifier were compared against subsequent biochar elemental composition, surface morphology and PAH content. Pine feedstock moisture (FM), with values of 7% and 17% was the experimental variable. Moderately high steady-state temperatures were observed inside the reactor, with a ca. 50°C difference in how the gasifier operated between the two feedstock types. Both chars exhibited surface properties comparable to activated carbon, but the relatively small differences in temperature caused significant variations in biochar surface area and morphology: micropore area 584 m2.g-1 (FM7%) against 360 m2.g-1 (FM17%), and micropore volume 0.287 cm3.g-1 (FM7%) against 0.172 cm3.g-1 (FM17%). Differences in char extractable PAH content were also observed, with higher concentrations (187 μg.g-1 15 ± 18) when the gasifier was operated with FM7%, compared to 89 ± 19 μg.g-1 Σ16EPA PAH with FM17%. It is recommended that greater detail on operational conditions during biochar production should be incorporated as standard to future biochar characterisation research as a consequence of these results

Characteristics of predictor sets found using differential prioritization

<p>Abstract</p> <p>Background</p> <p>Feature selection plays an undeniably important role in classification problems involving high dimensional datasets such as microarray datasets. For filter-based feature selection, two well-known criteria used in forming predictor sets are relevance and redundancy. However, there is a third criterion which is at least as important as the other two in affecting the efficacy of the resulting predictor sets. This criterion is the degree of differential prioritization (DDP), which varies the emphases on relevance and redundancy depending on the value of the DDP. Previous empirical works on publicly available microarray datasets have confirmed the effectiveness of the DDP in molecular classification. We now propose to establish the fundamental strengths and merits of the DDP-based feature selection technique. This is to be done through a simulation study which involves vigorous analyses of the characteristics of predictor sets found using different values of the DDP from toy datasets designed to mimic real-life microarray datasets.</p> <p>Results</p> <p>A simulation study employing analytical measures such as the distance between classes before and after transformation using principal component analysis is implemented on toy datasets. From these analyses, the necessity of adjusting the differential prioritization based on the dataset of interest is established. This conclusion is supported by comparisons against both simplistic rank-based selection and state-of-the-art equal-priorities scoring methods, which demonstrates the superiority of the DDP-based feature selection technique. Reapplying similar analyses to real-life multiclass microarray datasets provides further confirmation of our findings and of the significance of the DDP for practical applications.</p> <p>Conclusion</p> <p>The findings have been achieved based on analytical evaluations, not empirical evaluation involving classifiers, thus providing further basis for the usefulness of the DDP and validating the need for unequal priorities on relevance and redundancy during feature selection for microarray datasets, especially highly multiclass datasets.</p

Paramagnetic effect in YBaCuO grain boundary junctions

A detailed investigation of the magnetic response of YBaCuO grain boundary Josephson junctions has been carried out using both radio-frequency measurements and Scanning SQUID Microscopy. In a nominally zero-field-cooled regime we observed a paramagnetic response at low external fields for 45 degree asymmetric grain boundaries. We argue that the observed phenomenology results from the d-wave order parameter symmetry and depends on Andreev bound states.Comment: To be published in Phys. Rev.

Community participation in health services development, implementation, and evaluation: A systematic review of empowerment, health, community, and process outcomes.

BACKGROUND: Community participation is widely believed to be beneficial to the development, implementation and evaluation of health services. However, many challenges to successful and sustainable community involvement remain. Importantly, there is little evidence on the effect of community participation in terms of outcomes at both the community and individual level. Our systematic review seeks to examine the evidence on outcomes of community participation in high and upper-middle income countries. METHODS AND FINDINGS: This review was developed according to PRISMA guidelines. Eligible studies included those that involved the community, service users, consumers, households, patients, public and their representatives in the development, implementation, and evaluation of health services, policy or interventions. We searched the following databases from January 2000 to September 2016: Medline, Embase, Global Health, Scopus, and LILACs. We independently screened articles for inclusion, conducted data extraction, and assessed studies for risk of bias. No language restrictions were made. 27,232 records were identified, with 23,468 after removal of duplicates. Following titles and abstracts screening, 49 met the inclusion criteria for this review. A narrative synthesis of the findings was conducted. Outcomes were categorised as process outcomes, community outcomes, health outcomes, empowerment and stakeholder perspectives. Our review reports a breadth of evidence that community involvement has a positive impact on health, particularly when substantiated by strong organisational and community processes. This is in line with the notion that participatory approaches and positive outcomes including community empowerment and health improvements do not occur in a linear progression, but instead consists of complex processes influenced by an array of social and cultural factors. CONCLUSION: This review adds to the evidence base supporting the effectiveness of community participation in yielding positive outcomes at the organizational, community and individual level. TRIAL REGISTRATION: Prospero record number: CRD42016048244