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Acta Geochimica 1988年第4期7卷 329-335页

作者：赵斌 M.d.barton Institute of Geochemistry Academia Sinica Guiyang University of california. Los Angeles cA. 90024. U.S.A.

The compositions of more than 300 granets and pyroxenes from 14 contact--metasomatic calcic skarndeposits and calcic-magnesia skarn dkarn deposits in china have been examined using electron microprobetechnique. The compositions of garnets and pyroxenes from a wide variety of ore types represent ten majorclasses of calcic skarn deposits (Fe,Fe--cu,Pb-Zn,W,Sn,Sn-Mo-Bi-W,W--Bi-cu--Mo,cu--Zn and W-Zn-cu) and three major classes of calcic magnesia skarn deposits (Fe--cu,Mo,Pb-Zn). Garnets andpyroxenes show a wide range of variation in composition, but the majority of garnets are grossular--andraditesolid solutions containing less than 15 mo1% (spessartine+almandine+pyrope),whereas most pyroxenesare diopside-hedenbergite solid solutions containing less than 5 mo1% johannesenite. Some pyroxenes from aPb-Zn calcic--magnesia skarn deposit display an increase in Mn content. Only Sn--W calcic skarn deposits andPb-Zn calcic--magnesia skarn deposits contain garnets with more than 15 mo1% (spessartine+almandine+[pyrope). Some relationships have been established between the compositions of garnets and pyroxenes and themetallization types of econmically important metals in skarn deposits.

关键词： compositional characteristics of Garnets and Pyroxenes in contact-metasomatic Skarn deposits and Their Relationship with Metallization

Oligodendroglial heterogeneity in health,disease,and recovery:deeper insights into myelin dynamics

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Neural Regeneration Research 2025年第11期20卷 3179-3192页

作者： Pieter-Jan Serneels Julie d.de Schutter Lies de Groef Lieve Moons Steven Bergmans KU Leuven Leuven Brain InstituteDepartment of BiologyAnimal Physiology and Neurobiology DivisionNeural Circuit Development&Regeneration Research GroupLeuvenBelgium KU Leuven Leuven Brain InstituteDepartment of BiologyAnimal Physiology and Neurobiology DivisionCellular Communication&Neurodegeneration Research GroupLeuvenBelgium

decades of research asserted that the oligodendroglial lineage comprises two cell types:oligodendrocyte precursor cells and ***,recent studies employing single-cell RNA sequencing techniques have uncovered novel cell states,prompting a revision of the existing *** forward,the oligodendroglial lineage should be delineated into five distinct cell states:oligodendrocyte precursor cells,committed oligodendrocyte precursor cells,newly formed oligodendrocytes,myelin-forming oligodendrocytes,and mature *** new classification system enables a deeper understanding of the oligodendroglia in both physiological and pathological *** this uniform terminology will facilitate comparison and integration of data across ***,including the consolidation of findings from various demyelinating models,is essential to better understand the pathogenesis of demyelinating ***,comparing injury models across species with varying regenerative capacities can provide insights that may lead to new therapeutic strategies to overcome remyelination ***,by standardizing terminology and synthesizing data from diverse studies across different animal models,we can enhance our understanding of myelin pathology in central nervous system disorders such as multiple sclerosis,Alzheimer's disease,and amyotrophic lateral sclerosis,all of which involve oligodendroglial and myelin dysfunction.

关键词： animal models demyelination fish mammals multiple sclerosis myelin neurodegeneration oligodendrocytes oligodendroglial lineage remyelination

Understanding the need for pre-injection from permeability measurements: What is the connection?

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第3期11卷 576-597页

作者： Nick barton Eda Quadros Nick barton & Associates OsloNorway BGTech Soil and Rock Engineering Ltd. Sao PauloBrazil

Pre-grouting ahead of tunnels has three main functions:to control water inflow into the tunnel,to limit groundwater drawdown above the tunnel,and to make tunnelling progress more predictable since rock mass quality is effectively *** helps to avoid settlement damage caused by consolidation of clay deposits beneath built-up areas,since towns tend to be built where terrain is more flat,due to the clay *** are so many instances of settlement damage that the profession needs to take note of the need for high-pressure pre-grouting,to use micro-cements and micro-silica *** use of highpressure injection may cause joint jacking,but this is local in extent when the rapid pressure decay away from an injection hole is *** effect is variable and depends on the geometrical parameters of the *** pressure-decay advantage must not be violated by maintaining high pressure when grout flow from the injection hole has *** latter can cause damage to the grouting already *** methods of estimating mean hydraulic apertures(e)from Lugeon testing are described,and from more sophisticated three-dimensional(3d)permeability *** estimation of the larger mean physical joint apertures(E)is based on the joint roughness coefficient(JRc).comparison is then made with the empirical aperture-particle size criterion E>4d95,where d95 represents almost the largest cement particle *** on joint set orientations and on the available micro-cements,the decision must be made of which range of pre-injection pressure should be aimed for,using successive reductions of the water-cement ratio w/*** simple estimation of permeability,also with depth dependence,can be made with the empirical link between a modified rock mass quality Q and permeability,which is termed *** value of this parameter can be based on core-logging or intunnel face *** 3d before-and-after-grouting permeability measurements have been use

关键词： Pre-grouting Micro-cement Hydraulic apertures Physical joint apertures Joint roughness Particle size Anisotropic permeability

Risk of shear failure and extensional failure around over-stressed excavations in brittle rock

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第2期9卷 210-225页

作者： Nick barton Baotang Shen Nick barton&Associates OsloNorway cSIRO Energy BrisbaneAustralia

The authors investigate the failure modes surrounding over-stressed tunnels in *** lines of investigation are employed:failure in over-stressed three-dimensional(3d) models of tunnels bored under 3d stress,failure modes in two-dimensional(2d) numerical simulations of 1000 m and 2000 m deep tunnels using FRAcOd,both in intact rock and in rock masses with one or two joint sets,and finally,observations in TBM(tunnel boring machine) tunnels in hard and medium hard massive *** reason for 'stress-induced' failure to initiate,when the assumed maximum tangential stress is approximately(0.4-0.5)σ_c(UcS,uniaxial compressive strength) in massive rock,is now known to be due to exceedance of a critical extensional strain which is generated by a Poisson's ratio ***,because similar 'stress/strength' failure limits are found in mining,nuclear waste research excavations,and deep road tunnels in Norway,one is easily misled into thinking of compressive stress induced *** of this,the empirical SRF(stress reduction factor in the Q-system) is set to accelerate as the estimated ratio σ_(θmax)/σ_c >> *** mining,similar 'stress/strength' ratios are used to suggest depth of *** reality behind the fracture initiation stress/strength ratio of '0.4' is actually because of combinations of familiar tensile and compressive strength ratios(such as 10) with Poisson's ratio(say0.25).We exceed the extensional strain limits and start to see acoustic emission(AE) when tangential stress σθ ≈ 0.4σc,due to simple *** combination of 2d theoretical FRAcOd models and actual tunnelling suggests frequent initiation of failure by 'stable' extensional strain fracturing,but propagation in 'unstable' and therefore dynamic *** the case of very deep tunnels(and 3d physical simulations),compressive stresses may be too high for extensional strain fracturing,and shearing will dominate,both ahead of the face and following the *** shallower,the conc

关键词： Fracture propagation Tension Shear Poisson’s ratio Break-out Rock burst deep tunnels FRAcOd model

Experimental study on reduction of U (Ⅵ) by an anaerobic bacterium, Shewanella putrefaciens: Application to sandstone-hosted interlayer oxidation-zone type uranium deposits, china

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Science china Earth Sciences 2005年第3期48卷 346-352页

作者： L.L.barton department of Biology University of New Mexico Albuquerque NM 87131-1116USA

An experimental study on reduction of U (VI) by anaerobic bacteria, Shewanella putrefaciens, is first reported here in china. The experimental conditions were: 35℃ and pH = 7.0—7.4, corresponding to a physicochemical environments in which the sandstone-hosted in- terlayer oxidation-zone type uranium deposit formed in Northwest china’s Xinjiang. Bacteria adopted in the present experiment, Shewanella putrefaciens, occur extensively in natural envi- ronment. Our study shows that nano-crystal precipitates of uraninite quickly occurred on the surface of the cells within one week. It was found that the pitchblende was characterized by a random arrangement of uraninite nanocrystals (2—4 nm) in it, significantly different from natural pitchblende in which uraninite nanocrystals are arranged in order. Finally, a possible mechanism of uranium biomineralization by microorganisms in the deposits is discussed. Our investigation may supply a technical train of thoughts for bioremediation of nuclear-contaminated water envi- ronments and for underground dissolving extraction of the sandstone-hosted uranium ores.

关键词： anaerobic bacteria, reduction, pitchblende, sandstone-hosted uranium deposit, experimental study.

Is speciation driven by cycles of mixing and isolation?

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National Science Review 2019年第2期6卷 291-292页

作者： Nicholas H.barton Institute of Science and Technology Austria NSR

He et al.[1] describe genetic divergence between mangrove species that are distributed across the Straits of Malacca. divergence varies much more across the genome than in a simple null model of strict allopatry. Such heterogeneity (often termed ‘genomic islands of speciation’) can be generated by population structure:populations that exchange genes at a low rate will

关键词： Rev

Equatorial Wave Expansion of Instantaneous Flows for diagnosis of Equatorial Waves from data:Formulation and Illustration

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Advances in Atmospheric Sciences 2017年第10期34卷 1219-1234页

作者： cory barton Ming cAI Geophysical Fluid dynamics Institute Florida State UniversityTallahasseeFlorida32306USA department of Earth Oceanand Atmospheric ScienceFlorida State UniversityTallahasseeFlorida32306USA

This paper presents a method for expanding horizontal flow variables in data using the free solutions to the shallow-water system as a basis set. This method for equatorial wave expansion of instantaneous flows（EWEIF） uses dynamic constraints in conjunction with projections of data onto parabolic cylinder functions to determine the amplitude of all equatorial *** allows us to decompose an instantaneous wave flow into individual equatorial waves with a presumed equivalent depth without using temporal or spatial filtering a *** sets of EWEIF analyses are presented. The first set is to confirm that EWEIF is capable of recovering the individual waves constructed from theoretical equatorial wave solutions under various scenarios. The other two sets demonstrate the ability of the EWEIF method to derive time series of individual equatorial waves from instantaneous wave fields without knowing a priori exactly which waves exist in the data as well as their spatial and temporal scales using outputs of an equatorial β-channel shallow-water model and ERA-Interim data. The third set of demonstrations shows, for the first time, the continuous evolutions of individual equatorial waves in the stratosphere whose amplitude is synchronized with the background zonal wind as predicted by quasi-biennial oscillation theory.

关键词： Equatorial wave expansion Instantaneous flows equatorial β-channel shallow-water model

Shear strength criteria for rock,rock joints,rockfill and rock masses:Problems and some solutions

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Journal of Rock Mechanics and Geotechnical Engineering 2013年第4期5卷 249-261页

作者： Nick barton Nick barton & Associates OsloNorway

Although many intact rock types can be very strong,a critical confining pressure can eventually be reached in triaxial testing,such that the Mohr shear strength envelope becomes *** critical state has recently been better defined,and correct curvature or correct deviation from linear Mohr-coulomb（Mc） has finally been *** shear testing procedures for rock joints,using multiple testing of the same sample,in case of insufficient samples,can be shown to exaggerate apparent *** rough joints do not have any cohesion,but instead have very high friction angles at low stress,due to strong *** masses,implying problems of large-scale interaction with engineering structures,may have both cohesive and frictional strength ***,it is not correct to add these,following linear M-c or nonlinear Hoek-Brown（H-B） standard *** is broken at small strain,while friction is mobilized at larger strain and remains to the end of the shear *** criterion ＇c then σn tan φ＇ should replace ＇c plus σn tan φ＇ for improved fit to *** of principal stresses to a shear plane seems to ignore mobilized dilation,and caused great experimental difficulties until *** seems to be plenty of room for continued research,so that errors of judgement of the last 50 years can be corrected.

关键词： Rock masses critical state Rock joints Shear strength Non-linear friction cohesion dilation Scale effects Numerical modelling Stress transforms

Advances in joint roughness coefficient (JRc) and its engineering applications

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3352-3379页

作者： Nick barton changshuo Wang Rui Yong Nick barton&Associates Fjordveien 65cHavik Oslo1363Norway School of civil Engineeing Shijiazhuang Tiedao UniversityShijiazhuang050043China Rock Mechuanics Institute Ningbo UniversityNingbo315211China

The joint roughness coefficient (JRc), introduced in barton (1973) represented a new method in rock mechanics and rock engineering to deal with problems related to joint roughness and shear strength estimation. It has the advantages of its simple form, easy estimation, and explicit consideration of scale effects, which make it the most widely accepted parameter for roughness quantification since it was proposed. As a result, JRc has attracted the attention of many scholars who have developed JRc-related methods in many areas, such as geological engineering, multidisciplinary geosciences, mining mineral processing, civil engineering, environmental engineering, and water resources. Because of such a developing trend, an overview of JRc is presented here to provide a clear perspective on the concepts, methods, applications, and trends related to its extensions. This review mainly introduces the origin and connotation of JRc, JRc-related roughness measurement, JRc estimation methods, JRc-based roughness characteristics investigation, JRc-based rock joint property description, JRc's influence on rock mass properties, and JRc-based rock engineering applications. Moreover, the representativeness of the joint samples and the determination of the sampling interval for rock joint roughness measurements are discussed. In the future, the existing JRc-related methods will likely be further improved and extended in rock engineering.

关键词： Joint roughness coefficient(JRc) Rock joints Roughness Shear strength Scale effect

A comprehensive investigation on nonlinear vibration and bending characteristics of bio-inspired helicoidal laminated composite structures

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 81-100页

作者： S.SAURABH R.KIRAN d.SINGH R.VAISH V.S.cHAUHAN School of Mechanical and Materials Engineering Indian Institute of Technology Mandi

Bio-inspired helicoidal composite laminates, inspired by the intricate helical structures found in nature, present a promising frontier for enhancing the mechanical properties of structural designs. Hence, this study provides a comprehensive investigation into the nonlinear free vibration and nonlinear bending behavior of bio-inspired composite plates. The inverse hyperbolic shear deformation theory(IHSdT) of plates is employed to characterize the displacement field, with the incorporation of Green-Lagrange nonlinearity. The problem is modeled using the c0finite element method(FEM), and an in-house code is developed in the MATLAB environment to solve it numerically. Various helicoidal layup configurations including helicoidal recursive(HR), helicoidal exponential(HE), helicoidal semi-circular(HS), linear helicoidal(LH), and Fibonacci helicoidal(FH)with different layup sequences and quasi-isotropic configurations are studied. The model is validated, and parametric studies are conducted. These studies investigate the effects of layup configurations, side-to-thickness ratio, modulus ratios, boundary conditions, and loading conditions at different load amplitudes on the nonlinear vibration and nonlinear bending behaviors of bio-inspired composite plates. The results show that the laminate sequence exerts a substantial impact on both nonlinear natural frequencies and nonlinear bending behaviors. Moreover, this influence varies across different side-to-thickness ratios and boundary conditions of the bio-inspired composite plate.

关键词： Inverse problems