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

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

The talk with present the key results of the IPCC Working Group III 5th assessment report. Concluding four years of intense scientific collaboration by hundreds of authors from around the world, the report responds to the request of the world's governments for a comprehensive, objective and policy neutral assessment of the current scientific knowledge on mitigating climate change. The report has been extensively reviewed by experts and governments to ensure quality and comprehensiveness.

Climate change 2014 - Mitigation of climate change

Intermolecular And Surface Forces

Rapid growth in the market for electric vehicles is imperative, to meet global targets for reducing greenhouse gas emissions, to improve air quality in urban centres and to meet the needs of consumers, with whom electric vehicles are increasingly popular. However, growing numbers of electric vehicles present a serious waste-management challenge for recyclers at end-of-life. Nevertheless, spent batteries may also present an opportunity as manufacturers require access to strategic elements and critical materials for key components in electric-vehicle manufacture: recycled lithium-ion batteries from electric vehicles could provide a valuable secondary source of materials. Here we outline and evaluate the current range of approaches to electric-vehicle lithium-ion battery recycling and re-use, and highlight areas for future progress. Processes for dismantling and recycling lithium-ion battery packs from scrap electric vehicles are outlined.

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Recycling lithium-ion batteries from electric vehicles

Lithium sulfur (Li-S) batteries represent an interesting technology due to the high theoretical capacity of sulfur and the low cost of the cathode material. Li-S cells with graphite electrodes could be an option for low-cost stationary energy storage as graphite is cheap and the electrode production process is well established. Unfortunately, in most Li-S electrolytes, graphite is not stable due to solvent co-intercalation and degrades fast. In this work, a new low density electrolyte based on hexyl methyl ether (HME) and 1,3-dioxalane (DOL) is presented, which allows to use graphite as anode material for Li-S batteries. In symmetric graphite vs. graphite cells an averaged Coulombic efficiency of 99.94% per electrode could be reached. For the first time, cycling conditions like voltage window and balancing were optimized for Li-S cells with graphite anodes and the suitability of the concept could be demonstrated in multilayer pouch cells under realistic conditions. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/batt.202300093

An Ether‐Based Low Density Electrolyte for the Use of Graphite Anodes in Stable Lithium‐Sulfur Batteries

In this work the influence of the SoC and the SoH on the thermal runaway was analyzed in depth (SoC 30–100 % /SoH 75–100 %). Generally, the results show a decrease in the strength of the TR reactions with decreasing SoC/SoH. The determined surface temperatures decrease by >100 °C when SoC and SOH are reduced to 50 % SoC or 75 % SoH because there are fewer stored and active lithium ions as well as less overall stored energy and more inactive components. Released particles and gas caused a mass loss reduction of 12.5 % (SoC) and 7 % (SoH), respectively, with measurable gas concentrations of decomposition products and linear hydrocarbons decreasing. At the same time the concentrations of gaseous electrolyte components increase. A comparative analysis at SoC 80 % or SoH 80 % shows that the amount of stored energy or Li-ions incorporated at the time of penetration into the anode is responsible for the main reaction characteristics, which include the course of the voltage drop, the temperature evolution and the composition of the reaction gases. However, despite aging effects occurring with SoH reduction, the surface temperatures and determined gas concentrations reach the same values. At microscopic scale, changes in the reactions, e.g. SEI-decomposition, are expected, but no effect on the macroscopic TR is measurable. In general, it has been shown that both lower SoC and SoH minimize the severity of an occurring TR. In summary, it could be determined that cell surface temperatures drop by the same average values, up to 100 °C, for the same reduction in SoC and SoH. Gas concentrations decrease, as do cell mass loss parameters. With lower energy, the amount of carbonate compounds in the gas phase increases, with decomposition products increasing with increased energy. In general, it has been shown that both lower SoC and SoH minimize the severity of an occurring TR. In a comparative analysis of decreased SoC and SoH, it was shown that the type of decrease in stored Li-ion amounts, setting SoC 80 % or SoH 80 %, does almost not affect the macroscopically detectable responses of TR. The surface temperatures reached on the cell, as well as the gas concentrations determined and parameters such as the penetration depth to the TR and the mass loss show identical values for SoC 80 % and SoH 80 %. In the final analysis, it is the quantity of stored Li-ions that determines the effects and strength of the TR, and effects such as cyclic aging or state of charge are negligible on a macroscopic level. The results help to better allocate the effects of aging and charging to the utilization phase and existing hazards, and form the basis for further predictions and simulations. 

Comparison of the consequences of state of charge and state of health on the thermal runaway behavior of lithium ion batteries

The production of nanosuspensions of poorly soluble active pharmaceutical ingredients (API) is a popular technique to counteract challenges regarding bioavailability of such active substances. A subsequent drying of the nanosuspensions is advantageous to improve the long-term stability and the further processing into solid oral dosage forms. However, associated drying operations are critical, especially with regard to nanoparticle growth, loss in redispersibility and associated compromised bioavailability. This work extends a previous study regarding the applicability of an API (itraconazole) nanosuspension as a granulation liquid in a fluidized bed process with focus on the influence of applied formulation parameters on the structure of obtained nanoparticle-loaded granules and their nanoparticle redispersibility. Generally, a higher dissolution rate of the carrier material (glass beads, lactose, mannitol or sucrose) and a higher content of a matrix former/hydrophilic polymer (PVP/VA or HPMC) in the granulation liquid resulted in the formation of coarser and more porous granules with improved nanoparticle redispersibility. HPMC was found to have advantages as a polymer compared with PVP/VA. In general, a better redispersibility of the nanoparticles from the granules could be associated with better dispersion of the API nanoparticles at the surface of the granules as deduced from the thickness of nanoparticle-loaded layers around the granules. The layer thickness on granules was assessed by means of confocal Raman microscopy. Finally, the dispersion of the nanoparticles in the granule layers was exemplarily described by calculation of theoretical mean nanoparticle distances in the granule layers and was correlated with data obtained from redispersibility studies.

/pdf/evaluation-of-the-formulation-parameter-dependent-1wmiv7sv.pdf

Evaluation of the Formulation Parameter-Dependent Redispersibility of API Nanoparticles from Fluid Bed Granules

The production of functional particle systems is becoming increasingly important in many industries. In the early development of such products, there is often not a sufficient amount of educts available or the educts are expensive and/or toxic. For this purpose, lab-scale processes are used which often differ from the later production processes. Unfortunately, the processes have a direct impact on the product properties. That makes a subsequent transfer from the unconventional lab methods to the actual fabrication process necessary, which is often associated with problems. To avoid complex additional efforts in the development of new functional particle systems and, thus, shorten the time to market, a modular microfluidic spray dryer was developed. With our new microfluidic spray dryer made from glass, it is possible to produce droplet sizes and, thus, particle sizes similar to those of conventional spray dryers in the lab or even in the production but using only smallest quantities of starting materials (product volume flow rates down to 0.03 ml/min). During the development of the micro spray dryer, process and formulation parameters as well as various microchannel geometries were investigated to determine their influence on droplet formation and, thus, on product formation. The developed micro spray dryer can be operated with various formulations and material compositions, as the micro system is made of chemically inert material, is easy to clean, pressure-resistant and can be used in a wide range of pH values.

Arno Kwade

Papers

An Ether‐Based Low Density Electrolyte for the Use of Graphite Anodes in Stable Lithium‐Sulfur Batteries

Comparison of the consequences of state of charge and state of health on the thermal runaway behavior of lithium ion batteries

Evaluation of the Formulation Parameter-Dependent Redispersibility of API Nanoparticles from Fluid Bed Granules

Microfluidic spray drying device for process-oriented product development with low sample consumption

Moisture behavior of lithium-ion battery components along the production process