9 research outputs found
Wafer-Scale Assembly of Semiconductor Nanowire Arrays by Contact Printing
Controlled and uniform assembly of "bottom-up" nanowire (NW) materials with
high scalability has been one of the significant bottleneck challenges facing
the potential integration of nanowires for both nano and macro electronic
circuit applications. Many efforts have focused on tackling this challenge, and
while significant progress has been made, still most presented approaches lack
either the desired controllability in the positioning of nanowires or the
needed uniformity over large scales. Here, we demonstrate wafer-scale assembly
of highly ordered, dense, and regular arrays of NWs with high uniformity and
reproducibility through a simple contact printing process. We demonstrate
contact printing as a versatile strategy for direct transfer and controlled
positioning of various NW materials into complex structural configurations on
substrates. The assembled NW pitch is shown to be readily modulated through the
surface chemical treatment of the receiver substrate, with the highest density
approaching ~8 NW/um, ~95% directional alignment and wafer-scale uniformity.
Furthermore, we demonstrate that our printing approach enables large-scale
integration of NW arrays for various device structures on both Si and plastic
substrates, with a controlled semiconductor channel width, and therefore ON
current, ranging from a single NW (~10 nm) and up to ~250 um, consisting of a
parallel array of over 1,250 NWs.Comment: 14 pages,4 figure
Synthesis, Contact Printing, and Device Characterization of Ni-Catalyzed, Crystalline InAs Nanowires
InAs nanowires have been actively explored as the channel material for high
performance transistors owing to their high electron mobility and ease of ohmic
metal contact formation. The catalytic growth of non-epitaxial InAs nanowires,
however, has often relied on the use of Au colloids which is non-CMOS
compatible. Here, we demonstrate the successful synthesis of high yield of
crystalline InAs nanowires with high yield and tunable diameters by using Ni
nanoparticles as the catalyst material on amorphous SiO2 substrates. The
nanowires show superb electrical properties with field-effect electron mobility
~2,700 cm2/Vs and ION/IOFF >103. The uniformity and purity of the grown InAs
nanowires are further demonstrated by large-scale assembly of parallel arrays
of nanowires on substrates via the contact printing process that enables high
performance, printable transistors, capable of delivering 5-10 mA ON currents
(~400 nanowires).Comment: 21 pages, 5 figures included, all in .docx format. Nano Research (In
Press
Effects of flu vaccine, solely or accompanied by pneumovax-23 vaccine on clinical consequences of the respiratory diseases among Iranian pilgrims in Hajj
《法律史译评(2013年卷)》一书,将致力于刊载台湾学者的首发论文,以及日本、欧美等国最新研究成果的译文,并拟借此平台,推动海内外学界的及时沟通与交流,这是法史学界的一件功德事。《法律史译评(2013年卷)》对于研究视野的开阔、读史心得的相互砥砺,一定会有很大的帮助。International audienc
Three-dimensional nanopillar-array photovoltaics on low-cost and flexible substrates
Solar energy represents one of the most abundant and yet least harvested sources of renewable energy. In recent years, tremendous progress has been made in developing photovoltaics that can be potentially mass deployed1, 2, 3. Of particular interest to cost-effective solar cells is to use novel device structures and materials processing for enabling acceptable efficiencies4, 5, 6. In this regard, here, we report the direct growth of highly regular, single-crystalline nanopillar arrays of optically active semiconductors on aluminium substrates that are then configured as solar-cell modules. As an example, we demonstrate a photovoltaic structure that incorporates three-dimensional, single-crystalline n-CdS nanopillars, embedded in polycrystalline thin films of p-CdTe, to enable high absorption of light and efficient collection of the carriers. Through experiments and modelling, we demonstrate the potency of this approach for enabling highly versatile solar modules on both rigid and flexible substrates with enhanced carrier collection efficiency arising from the geometric configuration of the nanopillars
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Global mortality associated with 33 bacterial pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019
Summary
Background
Reducing the burden of death due to infection is an urgent global public health priority. Previous studies have estimated the number of deaths associated with drug-resistant infections and sepsis and found that infections remain a leading cause of death globally. Understanding the global burden of common bacterial pathogens (both susceptible and resistant to antimicrobials) is essential to identify the greatest threats to public health. To our knowledge, this is the first study to present global comprehensive estimates of deaths associated with 33 bacterial pathogens across 11 major infectious syndromes.
Methods
We estimated deaths associated with 33 bacterial genera or species across 11 infectious syndromes in 2019 using methods from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, in addition to a subset of the input data described in the Global Burden of Antimicrobial Resistance 2019 study. This study included 343 million individual records or isolates covering 11 361 study-location-years. We used three modelling steps to estimate the number of deaths associated with each pathogen: deaths in which infection had a role, the fraction of deaths due to infection that are attributable to a given infectious syndrome, and the fraction of deaths due to an infectious syndrome that are attributable to a given pathogen. Estimates were produced for all ages and for males and females across 204 countries and territories in 2019. 95% uncertainty intervals (UIs) were calculated for final estimates of deaths and infections associated with the 33 bacterial pathogens following standard GBD methods by taking the 2·5th and 97·5th percentiles across 1000 posterior draws for each quantity of interest.
Findings
From an estimated 13·7 million (95% UI 10·9–17·1) infection-related deaths in 2019, there were 7·7 million deaths (5·7–10·2) associated with the 33 bacterial pathogens (both resistant and susceptible to antimicrobials) across the 11 infectious syndromes estimated in this study. We estimated deaths associated with the 33 bacterial pathogens to comprise 13·6% (10·2–18·1) of all global deaths and 56·2% (52·1–60·1) of all sepsis-related deaths in 2019. Five leading pathogens—Staphylococcus aureus, Escherichia coli, Streptococcus pneumoniae, Klebsiella pneumoniae, and Pseudomonas aeruginosa—were responsible for 54·9% (52·9–56·9) of deaths among the investigated bacteria. The deadliest infectious syndromes and pathogens varied by location and age. The age-standardised mortality rate associated with these bacterial pathogens was highest in the sub-Saharan Africa super-region, with 230 deaths (185–285) per 100 000 population, and lowest in the high-income super-region, with 52·2 deaths (37·4–71·5) per 100 000 population. S aureus was the leading bacterial cause of death in 135 countries and was also associated with the most deaths in individuals older than 15 years, globally. Among children younger than 5 years, S pneumoniae was the pathogen associated with the most deaths. In 2019, more than 6 million deaths occurred as a result of three bacterial infectious syndromes, with lower respiratory infections and bloodstream infections each causing more than 2 million deaths and peritoneal and intra-abdominal infections causing more than 1 million deaths.
Interpretation
The 33 bacterial pathogens that we investigated in this study are a substantial source of health loss globally, with considerable variation in their distribution across infectious syndromes and locations. Compared with GBD Level 3 underlying causes of death, deaths associated with these bacteria would rank as the second leading cause of death globally in 2019; hence, they should be considered an urgent priority for intervention within the global health community. Strategies to address the burden of bacterial infections include infection prevention, optimised use of antibiotics, improved capacity for microbiological analysis, vaccine development, and improved and more pervasive use of available vaccines. These estimates can be used to help set priorities for vaccine need, demand, and development