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Polarized proton beams from laser-induced plasmas

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High Power Laser Science and Engineering 2019年第1期7卷 114-119页

作者： Anna Hützen Johannes Thomas Jürgen B?ker ralf engels ralf Gebel Andreas Lehrach Alexander Pukhov T.Peter Rakitzis Dimitris Sofikitis Markus Büscher Peter Grünberg Institut (PGI-6) Forschungszentrum Jülich Institut für Laser-und Plasmaphysik Heinrich-Heine-Universit?t Düsseldorf Institut für Theoretische Physik I Heinrich-Heine-Universit?t Düsseldorf Institut für Kernphysik (IKP-4) Forschungszentrum Jülich Institut für Kernphysik (IKP-2) Forschungszentrum Jülich JARA-FAME und III.Physikalisches Institut B RWTH Aachen Department of Physics University of Crete Institute of Electronic Structure and Laser Foundation for Research and Technology-Hellas

We report on the concept of an innovative source to produce polarized proton/deuteron beams of a kinetic energy up to several GeV from a laser-driven plasma accelerator. Spin effects have been implemented into the particle-in-cell(PIC) simulation code VLPL(Virtual Laser Plasma Lab) to make theoretical predictions about the behavior of proton spins in laser-induced plasmas. Simulations of spin-polarized targets show that the polarization is conserved during the acceleration process. For the experimental realization, a polarized HCl gas-jet target is under construction using the fundamental wavelength of a Nd:YAG laser system to align the HCl bonds and simultaneously circularly polarized light of the fifth harmonic to photo-dissociate, yielding nuclear polarized H atoms. Subsequently, their degree of polarization is measured with a Lamb-shift polarimeter. The final experiments, aiming at the first observation of a polarized particle beam from laser-generated plasmas, will be carried out at the 10 PW laser system SULF at SIOM, Shanghai.

关键词： laser-driven plasma accelerator particle-in-cell simulations polarized gas-jet target polarized proton beams

Importance of hydrogenotrophic, aceticlastic and methylotrophic methanogenesis for methane production in terrestrial, aquatic and other anoxic environments: A mini review

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Pedosphere 2020年第1期30卷 25-39页

作者： ralf CONRAD Max Planck Institute for Terrestrial Microbiology Karl-von-Frisch-Str.10Marburg 35043(Germany)

Microbial methanogenesis is a major source of the greenhouse gas methane(CH4).It is the final step in the anaerobic degradation of organic matter when inorganic electron acceptors such as nitrate,ferric iron,or sulfate have been *** of this degradation pathway is important for the creation of mechanistic models,prediction of future CH4 emission scenarios,and development of mitigation *** most anoxic environments,CH4 is produced from either acetate(aceticlastic methanogenesis)or hydrogen(H2)plus carbon dioxide(CO2)(hydrogenotrophic methanogenesis).Hydrogen can be replaced by other CO2-type methanogenesis,using formate,carbon monoxide(CO),or alcohols as *** ratio of these two pathways is tightly constrained by the stoichiometry of conversion *** the degradation of organic matter is complete(e.g.,degradation of straw in rice paddies),then fermentation eventually results in production of acetate and H2 at a ratio of>67%aceticlastic and<33%hydrogenotrophic ***,acetate production can be favored when heterotrophic or chemolithotrophic acetogenesis is enhanced,and H2 production can be favored when syntrophic acetate oxidation is *** typically occurs at low and elevated temperatures,***,temperature can strongly influence the methanogenic pathway,which may range from 100%aceticlastic methanogenesis at low temperatures to 100%hydrogenotrophic methanogenesis at high ***,if the degradation of organic matter is not complete(e.g.,degradation of soil organic matter),the stoichiometry of fermentation is not tightly constrained,resulting,for example,in the preferential production of H2,followed by hydrogenotrophic *** production of CH4 by either aceticlastic or hydrogenotrophic methanogenesis can also happen if one of the methanogenic substrates is not consumed by methanogens but is,instead,accumulated,volatilized,or utilized *** methano

关键词： electron acceptor fermentation methanogenic pathway organic matter degradation pH soil microbial community temperature Wood-Ljungdahl pathway

Sperm preparation： state-of-the-art--physiological aspects and application of advanced sperm preparation methods

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Asian Journal of Andrology 2012年第2期14卷 260-269页

作者： ralf Henkel Department of Medical Biosciences University of the Western Cape Bellville 7535 South Africa

For assisted reproduction technologies （ART）, numerous techniques were developed to isolate spermatozoa capable of fertilizing oocytes. While early methodologies only focused on isolating viable, motile spermatozoa, with progress of ART, particularly intracytoplasmic sperm injection （ICSI）, it became clear that these parameters are insufficient for the identification of the most suitable spermatozoon for fertilization. Conventional sperm preparation techniques, namely, swim-up, density gradient centrifugation and glass wool filtration, are not efficient enough to produce sperm populations free of DNA damage, because these techniques are not physiological and not modeled on the stringent sperm selection processes taking place in the female genital tract. These processes only allow one male germ cell out of tens of millions to fuse with the oocyte. Sites of sperm selection in the female genital tract are the cervix, uterus, uterotubal junction, oviduct, cumulus oophorus and the zona pellucida. Newer strategies of sperm preparation are founded oni （i） morphological assessment by means of＇motile sperm organelle morphological examination （MSOM E）＇; （ii） electrical charge; and （ili） molecular binding characteristics of the sperm cell. Whereas separation methods based on electrical charge take advantage of the sperm＇s adherence to a test tube surface or separate in an electrophoresis, molecular binding techniques use Annexin V or hyaluronic acid （HA） as substrates. Techniques in this category are magnet-activated cell sorting, Annexin V-activated glass wool filtration, flow cytometry and picked spermatozoa for ICSI （PICSI） from HA-coated dishes and HA-containing media. Future developments may include Raman microspectrometry, confocal light absorption and scattering spectroscopic microscopy and polarization microscopy.

关键词： advanced sperm selection biomimetics conventional sperm selection female genital tract physiological sperm selection

Bottomonium suppression in heavy-ion collisions and the in-medium strong force

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Nuclear Science and Techniques 2023年第4期34卷 185-187页

作者： ralf Rapp Cyclotron Institute and Department of Physics and Astronomy Texas A&M UniversityCollege StationTX 77843-3366USA

A large suppression of various bottomonium states in ultra-relativistic heavy-ion collisions has been reported by the STAR collaboration at the Relativistic Heavy-Ion *** observation is consistent with the formation of a quark-gluon plasma,but similar findings in more energetic collisions at the Large Hadron Collider suggest that a consistent picture requires additional *** states of a heavy quark (charm or bottom) and its antiquark,commonly referred to as quarkonia,have long been recognized as excellent probes of quark-gluon plasma(QGP) formation in high-energy collisions of atomic *** the vacuum,most quarkonium states are dominantly bound by a linearly rising potential (the so-called Cornell potential,see Fig.1),as a direct manifestation of the confinement property of Quantum Chromodynamics (QCD).

关键词： quark linearly vacuum

Leukocytes and oxidative stress： dilemma for sperm Function and male fertility

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Asian Journal of Andrology 2011年第1期13卷 43-52页

作者： ralf R Henkel Department of Medical Biosciences University of the Western Cape Bellville 7535 South Africa

Spermatozoa are constantly exposed to the interphase between oxidation through high amounts of reactive oxygen species （ROS） and leukocytes, and reduction by means of scavengers and antioxidants. Considering the very special functions as being the only cells with such high polarization and exerting their functions outside the body, even in a different individual, the female genital tract, the membranes of these cells are chemically composed of an extraordinary high amount of polyunsaturated fatty acids. This in turn, renders them very susceptible to oxidative stress, which is defined as an imbalance between oxidation and reduction towards the oxidative status. As a result, ROS deriving from both leukocytes and the male germ cells themselves cause a process called ＇lipid peroxidation＇ and other damages to the sperm cell. On the other hand, a certain limited amount of ROS iS essential in order to trigger vital physiological reactions in cells, including capacitation or the acrosome reaction in sperm. The treatment of patients with antioxidants to compensate the oxidative status caused by oxidative stress is highly debated as uncontrolled antioxidative treatment might derail the system towards the reduced status, which is also unphysiological and can even induce cancer. This paradox is called the ＇antioxidant paradox＇. Therefore, a proper andrological diagnostic work-up, including the evaluation of ROS levels and the antioxidant capacity of the semen, has to he carried out beforehand, aimed at keeping the fine balance between oxidation and scavenging of vital amounts of ROS.

关键词： antioxidants balance beneficial effects detrimental effects leukocytes male infertility reactive oxygen species sperm functions

Targeting copper to combat macrophage-driven inflammation: a potential advanced therapeutic strategy

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Signal Transduction and Targeted Therapy 2023年第10期8卷 4426-4427页

作者： ralf Weiskirchen Institute of Molecular Pathobiochemistry Experimental Gene Therapy and Clinical Chemistry(IFMPEGKC)RWTH University Hospital AachenPauwelsstr.30D-52074AachenGermany

In a recent paper published in Nature,Solier and coworkers showed that a rationally designed dimer of metformin targeting mitochondrial copper content can effectively oppose macrophage activation and plasticity.1 Since macrophages play critical roles in the initiation and maintenance of inflammation,this drug termed supformin holds promise to be a therapeutic effective in suppressing inflammation-related diseases related to macrophages.

关键词： inflammation therapeutic macrophage

Rainfall Algorithms Using Oceanic Satellite Observations from MWHS-2

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Advances in Atmospheric Sciences 2021年第8期38卷 1367-1378页

作者： Ruiyao CHEN ralf BENNARTZ Earth&Environmental Sciences Department Vanderbilt UniversityNashvilleTN 37235USA Space Science&Engineering Center University of Wisconsin-MadisonMadisonWI 53706USA

This paper describes three algorithms for retrieving precipitation over oceans from brightness temperatures (TBs) of the Micro-Wave Humidity Sounder-2 (MHWS-2) onboard Fengyun-3C (FY-3C). For algorithm development, scattering- induced TB depressions (ΔTBs) of MWHS-2 at channels between 89 and 190 GHz were collocated to rain rates derived from measurements of the Global Precipitation Measurement’s Dual-frequency Precipitation Radar (DPR) for the year 2017. ΔTBs were calculated by subtracting simulated cloud-free TBs from bias-corrected observed TBs for each channel. These ΔTBs were then related to rain rates from DPR using (1) multilinear regression (MLR);the other two algorithms, (2) range searches (RS) and (3) nearest neighbor searches (NNS), are based on k-dimensional trees. While all three algorithms produce instantaneous rain rates, the RS algorithm also provides the probability of precipitation and can be understood in a Bayesian framework. Different combinations of MWHS-2 channels were evaluated using MLR and results suggest that adding 118 GHz improves retrieval performance. The optimal combination of channels excludes high-peaking channels but includes 118 GHz channels peaking in the mid and high troposphere. MWHS-2 observations from another year were used for validation purposes. The annual mean 2.5° × 2.5° gridded rain rates from the three algorithms are consistent with those from the Global Precipitation Climatology Project (GPCP) and DPR. Their correlation coefficients with GPCP are 0.96 and their biases are less than 5%. The correlation coefficients with DPR are slightly lower and the maximum bias is ~8%, partly due to the lower sampling density of DPR compared to that of MWHS-2.

关键词： rainfall retrievals 118 GHz FY-3C MWHS-2 multilinear regression k-d tree

Advancements in personalized stem cell models for aging-related neurodegenerative disorders

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Neural Regeneration Research 2024年第11期19卷 2333-2334页

作者： Mingxi Weng ralf Jauch School of Biomedical Sciences Li Ka Shing Faculty of MedicineThe University of Hong KongHong Kong Special Administrative RegionChina Center for Translational Stem Cell Biology Hong Kong Special Administrative RegionChina

Neurodegenerative diseases(NDDs)are a class of disorders characterized by the gradual loss or malfunction of specific cell populations in the nervous system,which can be triggered by genetic or environmental *** a result,patients often experience a decline in mobility,sensation,memory,and cognition,which can ultimately lead to a fatal *** global incidence of NDDs,including Alzheimer’s disease,Parkinson’s disease,Huntington’s disease,amyotrophic lateral sclerosis(ALS),and multiple sclerosis,is increasing.

关键词： degenerative Huntington sensation

Reduced Sensitivity of Tropical Cyclone Intensity and Size to Sea Surface Temperature in a Radiative-Convective Equilibrium Environment

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Advances in Atmospheric Sciences 2018年第8期35卷 85-97页

作者： Shuai WANG ralf TOUMI State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography Space and Atmospheric Physics Group Department of PhysicsImperial College London

It has been challenging to project the tropical cyclone （TC） intensity, structure and destructive potential changes in a warming climate. Here, we compare the sensitivities of TC intensity, size and destructive potential to sea surface warming with and without a pre-storm atmospheric adjustment to an idealized state of Radiative-Convective Equilibrium （RCE）. Without RCE, we find large responses of TC intensity, size and destructive potential to sea surface temperature （SST） changes, which is in line with some previous studies. However, in an environment under RCE, the TC size is almost insensitive to SST changes, and the sensitivity of intensity is also much reduced to 3% ~C-1-4% ~C-1. Without the pre-storm RCE adjustment, the mean destructive potential measured by the integrated power dissipation increases by about 25% ~C-1 during the mature stage. However, in an environment under RCE, the sensitivity of destructive potential to sea surface warming does not change significantly. Further analyses show that the reduced response of TC intensity and size to sea surface warming under RCE can be explained by the reduced thermodynamic disequilibrium between the air boundary layer and the sea surface due to the RCE adjustment. When conducting regional-scale sea surface warming experiments for TC case studies, without any RCE adjustment the TC response is likely to be unrealistically exaggerated. The TC intensity-temperature sensitivity under RCE is very similar to those found in coupled climate model simulations. This suggests global mean intensity projections under climate change can be understood in terms of a thermodynamic response to temperature with only a minor contribution from any changes in large-scale dynamics.

关键词： tropical cyclone sea surface temperature radiative-convective equilibrium intensity size destructive potential