检索结果-南通市图书馆

Three- and Four-Dimensional Generalized Pythagorean Numbers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Pure Mathematics 2024年第1期14卷 1-15页

作者： Alfred wünsche Institute of Physics Humboldt University Berlin Germany

The Pythagorean triples (a, b | c) of planar geometry which satisfy the equation a2+b2=c2 with integers (a, b, c) are generalized to 3D-Pythagorean quadruples (a, b, c | d) of spatial geometry which satisfy the equation a2+b2+c2=d2 with integers (a, b, c, d). Rules for a parametrization of the numbers (a, b, c, d) are derived and a list of all possible nonequivalent cases without common divisors up to d2 is established. The 3D-Pythagorean quadruples are then generalized to 4D-Pythagorean quintuples (a, b, c, d | e) which satisfy the equation a2+b2+c2+d2=e2 and a parametrization is derived. Relations to the 4-square identity are discussed which leads also to the N-dimensional case. The initial 3D- and 4D-Pythagorean numbers are explicitly calculated up to d2, respectively, e2.

关键词： Number Theory Pythagorean Triples Tesseract 4-Square Identity Diophantine Equation

Structural engineering of antimicrobials for optimal broad-spectrum activity

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Green Chemical Engineering 2024年第4期5卷 473-482页

作者： Arunmozhiarasi Armugam Diane S.w.Lim Siti Nurhanna Riduan Shook Pui Chan Jerome Asugan Yugen Zhang Institute of Bioengineering and Bioimaging Institute of Sustainability for Chemicals Energy and Environment(ISCE2) Agency for Science Technology and Research (A*STAR) Diploma in Biomedical Science School of Chemical and Life SciencesSingapore Polytechnic

Antimicrobial materials are a crucial component in eradicating and managing the spread of infectious *** are expected to act on a broad-spectrum of microbes, including emerging pathogens which could cause the next Disease X. Herein, we reassessed a series of antimicrobial imidazolium polymers on our shelves and uncovered extended functionality through dual modes of action. By redesigning their structures, a truly broadspectrum antimicrobial material with optimized activity against bacteria(G +ve, G-ve) and fungi, as well as enveloped and non-enveloped viruses was developed. we demonstrated that the imidazolium polymer exhibits dual modes of function against microbes: targeting the microbial membrane and binding DNA. The latter DNA binding affinity was found to be key against non-enveloped viruses. with this insight, we designed small molecule compounds that exhibited optimum broad-spectrum antimicrobial activity and excellent efficacy against ESKAPE group of pathogens that are responsible for some of the deadliest nosocomial infections worldwide. Our results could also shed light on the design of broad-spectrum antimicrobial compounds against Disease X.

关键词： Broad-spectrum Antimicrobial Polyimidazolium Structure-function Membrane active

Convergence Phenomenon with Fourier Series of tg(x2)and Alike

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Advances in Pure Mathematics 2024年第7期14卷 556-595页

作者： Alfred wünsche Institut fr Physik Humboldt-Universitt Berlin Berlin Germany

The Fourier series of the 2π-periodic functions tg(x2)and 1sin(x)and some of their relatives (first of their integrals) are investigated and illustrated with respect to their convergence. These functions are Generalized functions and the convergence is weak convergence in the sense of the convergence of continuous linear functionals defining them. The figures show that the approximations of the Fourier series possess oscillations around the function which they represent in a broad band embedding them. This is some analogue to the Gibbs phenomenon. A modification of Fourier series by expansion in powers cosn(x)for the symmetric part of functions and sin(x)cosn−1(x)for the antisymmetric part (analogous to Taylor series) is discussed and illustrated by examples. The Fourier series and their convergence behavior are illustrated also for some 2π-periodic delta-function-like sequences connected with the Poisson theorem showing non-vanishing oscillations around the singularities similar to the Gibbs phenomenon in the neighborhood of discontinuities of functions. .

关键词： Gibbs Phenomenon Generalized Functions weak Convergence Chebyshev Polynomials of First and Second Kind Even and Odd Generating Functions for Chebyshev Polynomials Polylogarithms Completeness Relations

Regional trends and petrologic factors inhibit global interpretations of zircon trace element compositions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2024年第5期15卷 300-307页

作者： Nick M.w.Roberts Christopher J.Spencer Stephen Puetz C.Brenhin Keller Simon Tapster Geochronology and Tracers Facility British Geological SurveyNottingham NG125GGUK Department of Geological Sciences and Geological Engineering Queen’s UniversityKingstonOntarioCanada Atkinson Dr Suite 704HonoluluHI 96814USA Department of Earth Sciences Dartmouth CollegeHanoverNew HamphireUSA

The trace element composition of zircon reveals information about the melt that they are derived from,as such,detrital zircon trace element compositions can be used to interrogate melt compositions,and thus the evolution of the continental crust in time and ***,we present a global database of detrital zircon compositions and use it to test whether average global trends for five common petrogenetic proxies truly represent secular changes in continental *** demonstrate that the secular trend is broadly comparable across continental regions for Ti-in-zircon temperatures,but for other trace element ratios interrogated,secular trends are highly variable between continental *** trace element ratios result from multiple petrologic variables,we argue that these petrogenetic proxies can be overinterpreted if projected to global geologic *** particular,we caution against the interpretation of crustal thickness from trace elements in zircon,and we argue that our results negate current hypotheses concerning secular changes in crustal thickness.

关键词： Detrital zircon Trace elements Secular change Eu anomaly Crustal thickness

Reduction of epinephrine in the lumbar spinal cord following repetitive blast-induced traumatic brain injury in rats

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第7期19卷 1548-1552页

作者： Shigeharu Tsuda Mustafa Golam Jiamei Hou Kevin K.w.wang Floyd J.Thompson Prodip Bose Brain Rehabilitation Research Center Malcom Randall VA Medical CenterNorth Florida/South Georgia Veterans Health SystemGainesvilleFLUSA Department of Anesthesiology College of MedicineUniversity of FloridaGainesvilleFLUSA Department of Emergency Medicine University of FloridaGainesvilleFLUSA Department of Neuroscience University of FloridaGainesvilleFLUSA Department of Neurology University of FloridaGainesvilleFLUSA

Traumatic brain inju ry-induced unfavorable outcomes in human patients have independently been associated with dysregulated levels of monoamines,especially epinephrine,although few preclinical studies have examined the epinephrine level in the central nervous system after traumatic brain *** has been shown to regulate the activities of spinal motoneurons as well as increase the heart rate,blood pressure,and blood flow to the hindlimb ***,the purpose of the present study was to determine the impact of repeated blast-induced traumatic brain injury on the epinephrine levels in seve ral function-s pecific central nervous system regions in *** three repeated blast injuries at 3-day intervals,the hippocampus,motor cortex,locus coeruleus,vestibular nuclei,and lumbar spinal cord were harvested at post-injury day eight and processed for epinephrine assays using a high-sensitive electrochemical detector cou pled with high-performance liquid *** results showed that the epinephrine levels were significantly decreased in the lumbar spinal cord tissues of blast-induced traumatic brain injury animals compared to the levels detected in age-and sex-matched sham *** other function-specific central nervous system regions,although the epinephrine levels were slightly altered following blast-induced tra u matic brain injury,they were not statistically *** results suggest that blast injury-induced significant downregulation of epinephrine in the lumbar spinal cord could negatively impact the motor and cardiovascular *** is the first repo rt to show altered epinephrine levels in the spinal cord following repetitive mild blast-induced traumatic brain injury.

关键词： balance blood flow cardiovascular system central nervous system epinephrine ischemic damage lumbar spinal cord muscle tone repeated blast spasticity traumatic brain injury

Oil Palm Fiber Hybrid Composites: A Recent Review

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Renewable Materials 2024年第10期12卷 1661-1689页

作者： H.A.Aisyah E.Hishamuddin A.w.Noorshamsiana Z.Ibrahim R.A.Ilyas Biomass Technology Unit Engineering and Processing DivisionMalaysian Palm Oil Board(MPOB)6Persiaran InstitusiBandar Baru BangiKajangSelangor43000Malaysia Department of Chemical Engineering Faculty of Chemical and Energy EngineeringUniversiti Teknologi MalaysiaJohor81310Malaysia

Composite materials from oil palmﬁber enhance sustainability by utilizing renewable resources,reducing depen-dence on non-renewable materials,and lessening environmental *** their mechanical and dimen-sional stability limitations,oil palmﬁber-based polymer composites offer signiﬁcant advantages,such as natural abundance,potential weight reduction,and cost-effectiveness due to local availability and *** growing interest in oil palm hybrid composites,made from blending differentﬁbers,is due to their custo-mizable mechanical and physical *** is one of the most effective methods to reinforce and improve the performance of oil palm-derived composite *** review investigates the structural qualities of hybrid composites made from oil palmﬁbers,their suitability for diverse applications,and recent advancements in theﬁ*** focusing on the availability,properties,applications,challenges,and future direc-tions of oil palmﬁber hybrid composites,this review highlights the potential of these materials to enhance mechanical and functional properties,thereby contributing to sustainable development and innovation in com-posite materials.

关键词： Oil palmﬁber empty fruit bunch mesocarpﬁber hybrid composite

Precipitation transformation pathway and mechanical behavior of nanoprecipitation strengthened Fe-Mn-Al-C-Ni austenitic low-density steel

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第7期174卷 157-167页

作者： Y.F.An X.P.Chen L.Mei P.Ren D.wei w.Q.Cao College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Guangxi Engineering Research Center for Characteristic Metallic Powder Materials School of Electronic EngineeringGuangxi University of Science and TechnologyLiuzhou 545006China Central Iron&Steel Research Institute Beijing 100081China

Precipitation strengthening has been widely adopted in austenitic low-density steel owing to excellent hardened *** approach generally employs the coherentκ′carbides and non-coherent B2 *** the precipitation transformation pathway is decisive for further optimizing the microstructures under specific engineering ***,the detailed precipitation sequence of Fe-28Mn-11Al-1C-5Ni(wt%)austenitic low-density steel as well as its influence on mechanical prop-erties during aging process is systematically *** results reveal that nano-sizedκ′carbides domains(2 nm)exist in the solution-treated *** aging at 500℃for 1 h,the cuboidalκ′carbides(15-20 nm)uniformly disperse in austenite ***,after aging at 700℃for 15 min,the coarsenκ′carbides(30-35 nm)inhomogeneously distribute and align preferentially along the〈100〉***,extending the aging time to 60 min,the needle-type B2 particles replace theκ′carbides due to the enrichment of Ni elements at the phase boundaries among the austenite andκ′*** aging at 900℃,κ′carbides entirely dissolve into the austenite matrix,and the intragranular B2 particles are the sole precipitates in the austenite matrix and follow the K-S orientation relationship with *** work hardening capability seriously deteriorates due to the shearing ofκ′carbides by gliding *** the intragranular B2 particles preserve excellent work hardening rate by dislocations bow-out *** present work is meaningful for guiding the design of new generation dual-nano precipitation austenitic lightweight steel.

关键词： Lightweight steel κ′-carbides B2 particles work hardening capability

Precipitation of multi-type nano-quasicrystals in a Mg-Zn-Y alloy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第3期12卷 997-1008页

作者： w.Z.wang X.Z.Zhou L.F.Zhang H.Q.Ye Z.Q.Yang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of ScienceShenyang 110016China Ji Hua Laboratory Foshan 528251China Foshan University Foshan 528231China

Mg-6Zn-1Y(at.%)ribbons with strengthening precipitates of multi-type nanoquasicrystals were prepared by melt-spinning followed by aging *** evolution of the rapidly solidified ribbons during isothermal aging was comprehensively studied using various electron microscopy *** new kinds of decagonal quasicrystals were formed in aged ribbons,in addition to precipitation of nanometer icosahedral ***-resolution observations reveal that both decagonal quasicrystals can be modeled by quasiperiodic tiling with decagonal clusters of 2.5 nm in diameter,but overlap of neighboring clusters in both decagonal quasicrystals is different from the Gummelt model observed in other quasicrystals.A shell composed of complex Laves Mg-Zn domains was formed surrounding each decagonal quasicrystal precipitate upon prolonged *** addition,all kinds of nanoprecipitates exhibit excellent structure and size stability at 573 *** findings may have implications for not only fundamental studies about quasicrystals,but also microstructural manipulation of high-performance Mg alloys.

关键词： Quasicrystal Mg alloys Rapid solidification Scanning-transmission electron microscopy.

Reproductive cycle of the oyster Crassostrea(Magallana)saidii(wong and Sigwart,2021)from Southeast Asia

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Aquaculture and Fisheries 2024年第4期9卷 653-662页

作者： Arun Chandra Barman Nur Leena w.S.wong Murni Marlina Abd Karim Department of Aquaculture Faculty of AgricultureUniversiti Putra MalaysiaSerdangSelangor43400Malaysia Bangladesh Fisheries Research Institute(BFRI) Mymensingh2201Bangladesh International Institute of Aquaculture and Aquatic Sciences(I-AQUAS) Universiti Putra MalaysiaSerdangSelangor43400Malaysia

Crassostrea(Magallana)saidii has been commercially ranched in Malaysia and consumed for more than 160 years,but it was only recently identified as a new species to *** study was conducted to evaluate the reproductive phenology of C.(M.)*** of 30 individual oysters were taken monthly for 15 months from the sole population at Sungai Muar estuary in Johor,*** sex ratio was 1:1.64(male:female)for all examined specimens,with female numbers significantly *** was detected in 1.56%of all *** peaks in April(2019)and November(2018 and 2019),and were positively associated with the increased rainfall *** occurred throughout the research period with temporal *** highest values of maturity index(MI)were recorded in March,August and October 2019,when most oysters were in matured and maturing *** index(CI)ranged from 31.90±1.25(April 2019)to 70.03±3.23(October 2019),exhibiting two peaks(March and October 2019)and subsequently reduced in CI indicating spawning consistency with histological *** stressors such as heavy sedimentation and inland development are threatening the survival of this *** understanding of their reproductive biology is essential to ensure the survival and sustainability of C.(M.)saidii fishery.

关键词： Crassostrea(M.)saidii Gonad phenology Sex ratio Maturity index Condition index Oyster