Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Flexible and stretchable physical sensors that can measure and quantify electrical signals generated by human activities are attracting a great deal of attention as they have unique characteristics, such as ultrathinness, low modulus, light weight, high flexibility, and stretchability. These flexible and stretchable physical sensors conformally attached on the surface of organs or skin can provide a new opportunity for human-activity monitoring and personal healthcare. Consequently, in recent years there has been considerable research effort devoted to the development of flexible and stretchable physical sensors to fulfill the requirements of future technology, and much progress has been achieved. Here, the most recent developments of flexible and stretchable physical sensors are described, including temperature, pressure, and strain sensors, and flexible and stretchable sensor-integrated platforms. The latest successful examples of flexible and stretchable physical sensors for the detection of temperature, pressure, and strain, as well as their novel structures, technological innovations, and challenges, are reviewed first. In the next section, recent progress regarding sensor-integrated wearable platforms is overviewed in detail. Some of the latest achievements regarding self-powered sensor-integrated wearable platform technologies are also reviewed. Further research direction and challenges are also proposed to develop a fully sensor-integrated wearable platform for monitoring human activity and personal healthcare in the near future.

Flexible and Stretchable Physical Sensor Integrated Platforms for Wearable Human-Activity Monitoringand Personal Healthcare.

Background Tenofovir disoproxil fumarate (DF) is a nucleotide analogue and a potent inhibitor of human immunodeficiency virus type 1 reverse transcriptase and hepatitis B virus (HBV) polymerase. Methods In two double-blind, phase 3 studies, we randomly assigned patients with hepatitis B e antigen (HBeAg)–negative or HBeAg-positive chronic HBV infection to receive tenofovir DF or adefovir dipivoxil (ratio, 2:1) once daily for 48 weeks. The primary efficacy end point was a plasma HBV DNA level of less than 400 copies per milliliter (69 IU per milliliter) and histologic improvement (i.e., a reduction in the Knodell necroinflammation score of 2 or more points without worsening fibrosis) at week 48. Secondary end points included viral suppression (i.e., an HBV DNA level of <400 copies per milliliter), histologic improvement, serologic response, normalization of alanine aminotransferase levels, and development of resistance mutations. Results At week 48, in both studies, a significantly higher proportion of pat...

https://www.nejm.org/doi/pdf/10.1056/NEJMoa0802878

Tenofovir disoproxil fumarate versus adefovir dipivoxil for chronic hepatitis B

Printing sensors and electronics over flexible substrates are an area of significant interest due to low-cost fabrication and possibility of obtaining multifunctional electronics over large areas. Over the years, a number of printing technologies have been developed to pattern a wide range of electronic materials on diverse substrates. As further expansion of printed technologies is expected in future for sensors and electronics, it is opportune to review the common features, the complementarities, and the challenges associated with various printing technologies. This paper presents a comprehensive review of various printing technologies, commonly used substrates and electronic materials. Various solution/dry printing and contact/noncontact printing technologies have been assessed on the basis of technological, materials, and process-related developments in the field. Critical challenges in various printing techniques and potential research directions have been highlighted. Possibilities of merging various printing methodologies have been explored to extend the lab developed standalone systems to high-speed roll-to-roll production lines for system level integration.

https://cris.fbk.eu/bitstream/11582/300858/1/Technologies%20for%20Printing%20Sensors%20and%20Electronics%20Over%20Large%20Flexible%20Substrates-A%20Review.pdf

Technologies for Printing Sensors and Electronics Over Large Flexible Substrates: A Review

This progress report summarizes the numerous DPP-containing polymers recently developed for field-effect transistor applications including diphenyl-DPP and dithienyl-DPP-based polymers as the most commonly reported materials, but also difuranyl-DPP, diselenophenyl-DPP and dithienothienyl-DPP-containing polymers. We discuss the hole and electron mobilities that were reported in relation to structural properties such as alkyl substitution patterns, polymer molecular weights and solid state packing, as well as electronic properties including HOMO and LUMO energy levels. We moreover consider important aspects of ambipolar charge transport and highlight fundamental structure-property relations such as the relationships between the thin film morphologies and the charge carrier mobilities observed for DPP-containing polymers.

/pdf/recent-advances-in-the-development-of-semiconducting-dpp-wrsguz0z5g.pdf

Recent Advances in the Development of Semiconducting DPP‐Containing Polymers for Transistor Applications

Long-term beneficial outcome of Chinese asymptomatic patients with HBeAg-positive chronic hepatitis B on continuous lamivudine therapy: 7-year experience

Reducing the operating power and making them suitable for portable and wearable electronic applications are critical steps for the further development of organic field effect transistors (OFETs). One of the possible approaches to achieve this is by using a high dielectric constant (high-k) dielectric layer. Here, we propose a new kind of high-k amorphous Ba0.7Sr0.3TiO3 (BST) material derived by a layer-by-layer sol–gel method and solidified by UV-ozone treatments under atmospheric air and pressure. The dielectric constant of the amorphous BST thin film is around 11. Without employing the self-assembled monolayers (SAMs), the pentacene OFET on a polyethylene naphthalate (PEN) substrate shows saturation under −2.5 V, the saturation mobility of 0.252 cm2 V−1 s−1 with negligible hysteresis effects. The chemical composition of the dielectric film and the morphology structure are studied by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) respectively. We also performed compressive and tensile bending tests on the OFETs and the dielectric layer. Due to the amorphous nature of the BST thin film, it shows a constant C–f relationship in both compressive and tensile bending up to a bending radius of 3.3 mm. It demonstrates high application potential of the current BST thin film in flexible electronics and circuits. To confirm the application potentials, we develop an organic inverter based on the transistor and a resistor, and a gain as high as 20 can be achieved.

A UV-ozone treated amorphous barium–strontium titanate dielectric thin film for low driving voltage flexible organic transistors

In this study, junction-free silver network electrodes with a range of optical transparencies and sheet resistances are developed by using thermal evaporation in the cracked regions of polymer templates that have conformal coatings. In contrast to silver nanowire or carbon nanotube transparent conductive electrodes, there is no contact resistance of the silver mesh electrodes in the silver network, and no post process annealing treatment is required. We focus on investigating the degradation mechanisms of a silver network without junctions under different bias currents. We use CCD-based thermoreflectance microscopy to investigate the temperature variations of the network and locate the hot spots along the different conductive paths. From the distribution of the wasted heat, we notice that the reliability of the network strongly depends on the uniformity and percentage of areal coverage which can be adjusted by different spin-coating speed. A more regular network with an areal coverage of 18% can accommodate 2.6 times the bias current (140 mA) as opposed to that with an areal coverage of only 9% (54 mA) before breaking down. A finite element model is developed to simulate the temperature distribution and predict the breakdown locations of the transparent silver network. Based on the thermoreflectance and scanning electron microscope images of the network under different levels of degradation, we confirm that the primary cause of breakdowns is thermal assisted electromigration in the transparent silver network in this study.

Degradation mechanism of a junction-free transparent silver network electrode

A multijunction structure was applied on an organic photovoltaic (OPV) device for broadening the absorption spectrum and enhancing the power conversion efficiency through charge transfer process. By inserting the tris[4-(2-thienyl)]amine (TTPA) into a boron subphthalocyanine chloride (SubPc)/C60 OPV device, the short circuit current density (Jsc) showed a 47.5% increases from 3.05 to 4.50 mA/cm2 in the bilayer planar heterojunction device, while the open circuit voltage (Voc) remained constant. Based on the single junction (TTPA/SubPc) device and photoluminescence absorption results, we confirmed both TTPA/SubPc and SubPc/C60 junctions are contributing to the exciton dissociation process hence the efficiency enhancement.

/pdf/short-circuit-current-improvement-in-planar-heterojunction-gn0vf6gokd.pdf

Short circuit current improvement in planar heterojunction organic solar cells by multijunction charge transfer

By generating high resolution two dimensional temperature images of electronic devices and linking heat dissipation to electrical current, the authors demonstrate that thermoreflectance measurements employing a charge-coupled device can provide a useful and nondestructive method for profiling current density in electronic devices. Here they apply this method to high power SiGe heterojunction bipolar transistors (HBTs) integrated in a commercial SiGe bipolar complementary metal-oxide-semiconductor platform, measuring the current carried by each subcell and quantifying current collapse under high-bias operation. They show that current hogging for a HBT with two emitter subcells can lead to one subcell carrying 81% of the total current.

/pdf/thermoreflectance-imaging-of-current-dynamics-in-high-power-4m372eyx5p.pdf

Paddy K. L. Chan

Papers

Long-term beneficial outcome of Chinese asymptomatic patients with HBeAg-positive chronic hepatitis B on continuous lamivudine therapy: 7-year experience

A UV-ozone treated amorphous barium–strontium titanate dielectric thin film for low driving voltage flexible organic transistors

Degradation mechanism of a junction-free transparent silver network electrode

Short circuit current improvement in planar heterojunction organic solar cells by multijunction charge transfer

Thermoreflectance imaging of current dynamics in high power SiGe heterojunction bipolar transistors