52 research outputs found

    Digital photoprogramming of liquid-crystal superstructures featuring intrinsic chiral photoswitches

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    Dynamic patterning of soft materials in a fully reversible and programmable manner with light enables applications in anti-counterfeiting, displays and labelling technology. However, this is a formidable challenge due to the lack of suitable chiral molecular photoswitches. Here, we report the development of a unique intrinsic chiral photoswitch with broad chirality modulation to achieve digitally controllable, selectable and extractable multiple stable reflection states. An anti-counterfeiting technique, embedded with diverse microstructures, featuring colour-tunability, erasability, reversibility, multi-stability and viewing-angle dependency of pre-recorded patterns, is established with these photoresponsive superstructures. This strategy allows dynamic helical transformation from the molecular and supramolecular to the macroscopic level using light-activated intrinsic chirality, demonstrating the practicality of photoprogramming photonics

    The epidemiology of Plasmodium vivax and Plasmodium falciparum malaria in China, 2004–2012: from intensified control to elimination

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    BACKGROUND In China, the national malaria elimination programme has been operating since 2010. This study aimed to explore the epidemiological changes in patterns of malaria in China from intensified control to elimination stages. METHODS Data on nationwide malaria cases from 2004 to 2012 were extracted from the Chinese national malaria surveillance system. The secular trend, gender and age features, seasonality, and spatial distribution by Plasmodium species were analysed. RESULTS In total, 238,443 malaria cases were reported, and the proportion of Plasmodium falciparum increased drastically from <10% before 2010 to 55.2% in 2012. From 2004 to 2006, malaria showed a significantly increasing trend and with the highest incidence peak in 2006 (4.6/100,000), while from 2007 onwards, malaria decreased sharply to only 0.18/100,000 in 2012. Males and young age groups became the predominantly affected population. The areas affected by Plasmodium vivax malaria shrunk, while areas affected by P. falciparum malaria expanded from 294 counties in 2004 to 600 counties in 2012. CONCLUSIONS This study demonstrated that malaria has decreased dramatically in the last five years, especially since the Chinese government launched a malaria elimination programme in 2010, and areas with reported falciparum malaria cases have expanded over recent years. These findings suggest that elimination efforts should be improved to meet these changes, so as to achieve the nationwide malaria elimination goal in China in 2020.This study was supported by grants from the Ministry of Science and Technology of China (2012ZX10004-201, 2012ZX10004-220) and the Ministry of Health of China (No. 201202006), and China UK Global Health Support Programme (grant no. GHSP-CS-OP1). S.I.H. is funded by a Senior Research Fellowship from the Wellcome Trust (#095066). S.I.H. also acknowledges funding support from the RAPIDD programme of the Science & Technology Directorate, Department of Homeland Security, and the Fogarty International Center, National Institutes of Health

    Design of a Capacitive MEMS Accelerometer with Softened Beams

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    Lower stiffness can improve the performance of capacitive-based microelectromechanical systems sensors. In this paper, softened beams, achieved by the electrostatic assembly approach, are proposed to lower the stiffness of a capacitive MEMS accelerometer. The experiments show that the stiffness of the accelerometer is reduced by 43% with softened beams and the sensitivity is increased by 72.6%. As a result, the noise of the accelerometer is reduced to 26.2 &mu;g/&radic;Hz with an improvement of 44.5%, and bias instability is reduced to 5.05 &mu;g with an enhancement of 38.7%. The electrostatic assembly-based stiffness softening technique is proven to be effective and can be used in many types of MEMS devices

    A peak shape model with high-energy tailing for high-resolution alpha-particle spectra

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    The measurement of alpha-particle spectra using semiconductor silicon detectors is an important radioactive analysis method for alpha emitters. It is a common situation that the peaks of alpha-particles with nearby energies are overlapping even with high-resolution alpha-particle spectrometry. In this work, an improved peak shape model named EMG-Landau (Exponentially Modified Gaussian with Landau), taking the high-energy tailing into account, was proposed based on the traditional EMG (Exponentially Modified Gaussian) model. Then the EMG-Landau model was effectively tested by using IAEA reference alpha spectra for unfolding performance and EUROMET reference alpha spectra for estimating the activity ratio. Compared with the traditional EMG model, the EMG-Landau model could be more accurate to fit high-resolution alpha spectra with high-energy tailing

    Laser rapid drilling of bone tissue in minimizing thermal injury and debris towards orthopedic surgery

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    Traditional mechanical bone drilling is prone to heat generation and debris accumulation which will cause tissue damage in orthopedic surgeries. Therefore, research on contactless laser bone drilling has become a mainstream trend in the development of bone surgery. This study presents a laser rapid drilling strategy for bone surgery with minimizing thermal osteonecrosis and debris based on the design of dynamic focusing and spreading droplet cooling. The laser drilled hole suffered from low temperature (Tmax = 46.2 ○C) under clinically accepted threshold of 47 ○C, presenting osteocyte-filled lacunas, visible Haversian canals and increased pullout strength when compared with that following mechanically drilling. An intact bone column without debris was extracted from a 4-mm-deep hole in vitro on a sheep tibia which provides a clean surgical method with increased drilling rate of 0.94 mm3/s. The criteria dimensionless We constant related to spreading droplets leading to effective heat transfer is determined as2.8 × 103 × Re-1/2 ≤ We ≤ 1.9 × 10-2 × Re7, yielding a high convective coefficient of 0.11 W/mm2·K for cooling. The comprehensive results of laser bone drilling proved the effectiveness of the presented technology and setup, which is significant in realizing rapid, debris-free orthopedic surgery

    The epidemiology of Plasmodium vivax and Plasmodium falciparum malaria in China, 2004-2012: from intensified control to elimination

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    BackgroundIn China, the national malaria elimination programme has been operating since 2010. This study aimed to explore the epidemiological changes in patterns of malaria in China from intensified control to elimination stages.MethodsData on nationwide malaria cases from 2004 to 2012 were extracted from the Chinese national malaria surveillance system. The secular trend, gender and age features, seasonality, and spatial distribution by Plasmodium species were analysed.ResultsIn total, 238,443 malaria cases were reported, and the proportion of Plasmodium falciparum increased drastically from &lt;10% before 2010 to 55.2% in 2012. From 2004 to 2006, malaria showed a significantly increasing trend and with the highest incidence peak in 2006 (4.6/100,000), while from 2007 onwards, malaria decreased sharply to only 0.18/100,000 in 2012. Males and young age groups became the predominantly affected population. The areas affected by Plasmodium vivax malaria shrunk, while areas affected by P. falciparum malaria expanded from 294 counties in 2004 to 600 counties in 2012.ConclusionsThis study demonstrated that malaria has decreased dramatically in the last five years, especially since the Chinese government launched a malaria elimination programme in 2010, and areas with reported falciparum malaria cases have expanded over recent years. These findings suggest that elimination efforts should be improved to meet these changes, so as to achieve the nationwide malaria elimination goal in China in 2020
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