Bulk Grain Research Articles

Organische Kohlenstoffvorräte von Bodentypen in den Hauptnaturräumen Schleswig-Holsteins (Norddeutschland)

Zusammenfassung Die Verbesserung der Humusspeicherung in Böden im Hinblick auf eine nachhaltige Landbewirtschaftung erfordert genaue Kenntnisse über den organischen Kohlenstoff(Corg)-Vorrat in Böden, wobei auch die Wechselwirkungen zwischen Bodentyp, geologischem Ausgangsgestein sowie Landnutzung berücksichtigt werden müssen. Auf der Grundlage von insgesamt 925 Bodenprofilen in den vier Hauptnaturräumen (Östliches Hügelland, Vorgeest, Hohe Geest und Marsch) Schleswig-Holsteins (Norddeutschland) wurde der Corg-Vorrat bis in eine Tiefe von 90 cm quantifiziert. Die horizontspezifischen Parameter (u. a. auch Trockenrohdichte und Korngrößenverteilung) wurden im Rahmen der seit ca. 1970 durchgeführten bodenkundlichen Leitprofilaufnahmen vom Landesamt für Landwirtschaft, Umwelt und ländliche Räume Schleswig-Holstein (LLUR) und deren Vorgängerbehörden erhoben. Die vier Hauptnaturräume enthalten unterschiedliche Corg-Vorräte in den Bodentiefen 0–30, 30–60 und 60–90 cm. Insgesamt werden in Schleswig-Holstein mindestens 244 Mt Corg (0–90 cm Tiefe) gespeichert, wobei je nach Landnutzung, Bodentyp und geologischem Ausgangsgestein deutliche Unterschiede auftreten. Im Oberboden variieren die Corg-Vorräte von ca. 60 t/ha (Ackerböden der Marsch/des Östlichen Hügellands) bis ca. 130 t/ha (Grünlandböden der Geest). Im Unterboden verfügen neben den Mooren die humusreichen Marschböden, die Kolluvisole (Alt- und Jungmoränengebiet) und Gley-Podsole (Hohe Geest und Vorgeest) über die höchsten Corg-Vorräte bis 90 cm Tiefe. Das Speicher- und Verlustpotenzial von Humusmengen durch einen Landnutzungswechsel ist daher auch bodentypspezifisch zu bewerten.

Observations of the effects of benthic biology in measurements from the Acoustic Coring System collected in the New England Mud Patch

This paper presents in situ measurements of sediment sound speed and attenuation collected in the New England Mud Patch using the Acoustic Coring System (ACS) with comparisons to sound speed measurements from a multi-sensor core logger (MSCL). The ACS uses rod-mounted piezoelectric cylinders mounted below the penetrating tip of a gravity corer to obtain a continuous record of sound speed as a function of depth as the corer penetrates the seabed. The MSCL measurements of the recovered sediment cores were acquired in 2 cm increments. In both the ASC and MSCL measurements, an elevated sound speed is observed in the upper 25 cm of the seabed which is the portion of the seabed where most infauna live. The sediments collected in the cores were analyzed for density, porosity, bulk organic matter, carbonate content, mineral composition, and grain size. Additional surficial sediment samples recovered using a box core and a multi-core were sieved for infauna collection. The organisms were preserved, identified, and classified according to acoustically relevant traits. The acoustic measurements are interpreted in terms of the physical measurements of cores and the abundance of different types of organisms present in the seabed. [Work supported by ONR.]

ZHUHONG OINTMENT PROMOTES CHRONIC WOUND HEALING BY REGULATING INFLAMMATORY RESPONSE, ENZYME ACTIVITY AND NEUTROPHIL APOPTOSIS

Variations in the moisture content (MC) of grains strongly influence machine performance analysis during crop harvesting and post-harvest grain handling operations. For experimental or numerical methods such as discrete element method (DEM) technique to include the effect of MC on physical and mechanical properties, comprehensive study was conducted to investigate the effect of maize MC on single kernel properties and bulk grain dynamic responses, which have relevance for DEM crop model calibration. Individual kernel properties of shape, size, coefficient of restitution, and stiffness, and bulk material responses of bulk density, angle of repose, direct shear test (angle of internal friction, apparent cohesion), hopper flowability, and grain-machine interaction (GMI) impact plate forces responses were measured on maize samples at 11%, 16%, and 26% MC levels. At individual particle responses of coefficient of restitution and stiffness, maize kernels at MC of 26% had significantly the lowest values compared to the values at the other MC (11% and 16%). Increasing maize MC reduced the hopper discharge flowability by 20% and GMI impact plate forces by 25%. Significant effects of MC on the material behaviours should be considered for calibration of DEM maize models.

A Model for High-Cycle Fatigue in Polycrystals

A grain-scale formulation for high-cycle fatigue inter-granular degradation in polycrystalline aggregates is presented. The aggregate is represented through Voronoi tessellations and the mechanics of individual bulk grains is modelled using a boundary integral formulation. The inter-granular interfaces degrade under the action of cyclic tractions and they are represented using cohesive laws embodying a local irreversible damage parameter that evolves according to high-cycle continuum damage laws. The consistence between cyclic and static damage, which plays an important role in the redistribution of inter-granular tractions upon cyclic degradation, is assessed at each fatigue solution jump, so to capture the onset of macro-failure. Few polycrystalline aggregates are tested using the developed technique, which may find application in multiscale modelling of engineering components as well as in the design of micro-electro-mechanical devices (MEMS).

Fast Ion Conducting Solid-State Electrolytes for Sodium Ion Batteries — from Elementary Steps to Macroscopic Transport

All-solid-state batteries and especially solid electrolytes stand in the spotlight of current energy research.[1,2] An extremely high ion mobility, which is known for liquid electrolytes, is needed to realize batteries with ceramic electrolytes. Apart from Li-bearing materials also a range of sodium compounds exhibit extremely high ion conductivities. With regard to availability and costs Na-based energy storage systems have attracted great interest over the last years.[3] Here we re-investigated the most prominent representatives of this kind of functional materials viz. Na-β''-alumina[4] and Na3Zr2(SiO4)2PO4 (NASICON), which are known to show conductivity values in the order of mS/cm at RT.[5,6] We used high precision impedance measurements and nuclear magnetic resonance (NMR) spectroscopy to study the diffusion mechanisms and long-range ion transport. In the case of Na-β''-alumina we focused on a commercially available sintered pellets to investigate both bulk dynamics and grain boundary effects on ionic conductivity. Impedance spectroscopy was helpful to interpret ion dynamics revealed by NMR on both short as well as long-range length scales. For well-sintered and highly dense samples ion transport across grain boundaries has only little impact on the overall fast ion transport seen.

Processing, dielectric and impedance spectroscopy of lead free BaTiO3-BiFeO3-CaSnO3

The paper presents the fabrication and characterization of structural and electrical properties of an electronic composite of three perovskites: BaTiO3, BiFeO3 and CaSnO3 in a fixed ratio of 80/13/07 (i.e., 0.80(BaTiO3)-0.13(BiFeO3)-0.07(CaSnO3) (referred as BTO-BFO-CSO-7)) using standard experimental techniques. Analysis of room temperature X-ray diffraction spectra helps to determine the crystal system and unit cell dimensions (lattice parameters) of the sample. The dielectric and impedance spectroscopy was used to study the resistive (impedance, complex electrical modulus and electrical transport properties) and insulating (dielectric) characteristics of the prepared electronic material at various frequencies (102–106 Hz) and temperatures (20–450 °C). Study of the Nyquist plot confirms the presence of temperature dependent bulk (grain) effect only and negative temperature coefficient resistance in the BTO-BFO-CSO-7 composite. Analysis of conductivity spectra reveals that the charge transfer by hopping contributes to the electrical transport process. The dielectric relaxation of the sample is studied using complex modulus spectra. This study also helps to understand the mechanism of the electrical transport process, which depicts a non-Debye type of conductivity relaxation. The magnetic hysteresis loop (M − H) shows a remanent magnetization of 0.031 emu/g.

Нетрадиційні методи зберігання зерна для виробництва органічної продукції

The purpose. To determine and justify methods which ensure protection of grain at storage, for manufacture integrally net produce without application of any chemically aggressive substances. Methods. Analysis of known non-conventional methods of protection of grain during storage: thermal disinfection, treatment by microwave field, ozonation, control gaseous medium, laser bombarding radiation. Own researches in storage of grain of corn in conditions of modified gaseous medium. Results. Features of different methods of protection of grain and parameters of modified gaseous medium which ensure long-term resistant storage of corn depending on its temperature and damp are probed. Thermal disinfection is an efficient method in technique of storage of grain for struggle against warehouse pests. Treatment by microwave field is disinfection of grain from microorganisms which during the vital activity produce poisonous substances. Ozonation is physical and chemical method of disinfection of grain. Time of biological longevity of different crops on indexes of their vital activity is specified. Conclusions. Method of storage of grain of corn in the modified gaseous medium with the following parameters is offered: O2 (content of oxygen) — 4–5%, W (damp of grain) — 10–12%, t (temperature of grain) — 3–10°C. Other methods are unstable and their efficiency depend on state of bulk grain.

Segregation assisted grain boundary precipitation in a model Al-Zn-Mg-Cu alloy

Understanding the composition evolution of grain boundaries and grain boundary precipitation at near-atomic scale in aluminum alloys is crucial to tailor mechanical properties and to increase resistance to corrosion and stress corrosion cracking. Here, we elucidate the sequence of precipitation on grain boundaries in comparison to the bulk in a model Al-Zn-Mg-Cu alloy. We investigate the material from the solution heat treated state (475 °C), through the very early stages of aging to the peak aged state at 120 °C and further into the overaged regime at 180 °C. The process starts with solute enrichment on grain boundaries due to equilibrium segregation accompanied by solute depletion in their vicinity, the formation of Guinier–Preston (GP) zones in the solute-enriched grain boundary regions, and GP zones growth and transformation. The equilibrium segregation of solutes to grain boundaries during aging accelerates this sequence compared to the bulk. Analysis of the ∼10 nm wide precipitate-free zones (PFZs) adjacent to the solute-enriched grain boundaries shows that the depletion zones are determined by (i) interface equilibrium segregation; (ii) formation and coarsening of the grain boundary precipitates and (iii) the diffusion range of solutes in the matrix. In addition, we quantify the difference in kinetics between grain boundary and bulk precipitation. The precipitation kinetics, as observed in terms of volume fraction, average radius, and number density, is almost identical next to the depletion zone in the bulk and far inside the bulk grain remote from any grain boundary influence. This observation shows that the region influenced by the grain boundaries does not extend beyond the PFZs.

Hydrostatic Extrusion Experiment on AZ80 Magnesium Alloy Tube-Expanding Forming under Ultra-High Pressure

A series of systematic experiments were completed on self-developed ultra-high pressure hydrostatic extrusion equipment to determine the effects of key process parameters on AZ80 magnesium alloy tube-expanding forming. Compared with other parameters, extrusion ration has a significant impact on maximum extrusion pressure and unloading pressure. Through material performance tests, highest average tensile ultimate strength (380.0Mpa) and average tensile yield strength (369.3Mpa) was obtained at homogenization temperature of billet 400°C, homogenization time of billet 32h, preheating temperature of extrusion cylinder 180°C, extrusion ratio 2.77 and angle of core die 120°, accompanied by elongation percentage 7%. In the condition of experiment NO.13 (homogenization temperature of billet 400°C, homogenization time of billet 16h, preheating temperature of extrusion cylinder 220°C, extrusion ratio 1.25 and angle of core die 120°), tensile strength, yield strength and elongation percentage achieved a balanced combination with relative low extrusion pressure. Metallographic test also indicates that the ductility of expanding forming tube still has improving potential by annealing recrystallization or other post-treatment processes which is effective to completely eliminate the bulk grain.

Study of structural, electrical and magnetic properties of 1−x(Ba0.96Ca0.04TiO3)−x(BiFeO3) ceramics composites

Lead free 1−x(Ba0.96Ca0.04TiO3)−x(BiFeO3) (abbreviated as BCT–BF) ceramics were prepared by solid state reaction method. The structural studies were carried out by using XRD technique, which confirms that the samples have a tetragonal, with the cubic spinel ferrite phase at room temperature. Dielectric and impedance properties of BCT–BF ceramics have been characterized at different temperature and in 1 kHz–1 MHz frequency range. The complex impedance plot exhibited one semi-circle at higher temperatures. Centers of the semicircles lie below the real axis, which confirms that the material is the non-Debye type. Single semicircle indicating that bulk grain effect are dominated in system. Bulk resistance decreased with the increase of temperature, which indicating the negative temperature coefficient of resistance behavior in our samples. The activation energy determined from an Arrhenius type plot of conductivity (at 1 kHz) was also found to increase from 0.22 eV (x = 0.10) to 1.41 eV (x = 0.30), which is close to half of the optical band gap, suggesting a change in conduction mechanism due to extrinsic defects.

Corrosion of Structural Alloys in High-Temperature Molten Fluoride Salts for Applications in Molten Salt Reactors

Hastelloy N®, a nickel-based alloy, and 316 stainless steel are among the candidate structural materials being considered for the construction of the molten salt reactor (MSR). Most of the proposed MSR concepts use molten fluoride salts as coolant which can be quite corrosive to structural alloys. The results of studies on the corrosion behavior of the two alloys in molten Li2BeF4 (FLiBe) salt at 700°C are discussed. This salt is being considered as the primary coolant for MSR designs featuring solid fuel particles, but the reported results also provide insights into the corrosion in MSR designs where the uranium fuel is dissolved in the molten fluoride salt. Corrosion was observed to occur predominantly by de-alloying of Cr from the alloy surface and into the molten salt, with more pronounced attack occurring along the grain boundaries than in the bulk grains. The magnitude and the mechanisms of corrosion were different for corrosion tests performed in graphite and metallic capsules, a result warranting recognition given the coexistence of structural alloys and graphite in the molten salt medium in the MSR.

Solid solution limits and electrical properties of scheelite SryLa1-yNb1-xVxO4-δ materials for x = 0.25 and 0.30 as potential proton conducting ceramic electrolytes

The proton conductivity and solid solubility limits of acceptor strontium doped vanadium stabilised lanthanum niobate (SryLa1−yNb1-xVxO4-δ, x = 0.25, 0.30 and y = 0 to 0.10) were explored as potential proton conducting ceramic electrolytes. All samples were synthesized via a solid-state method. The phase purity, microstructure and thermal expansion behaviour of the materials were studied using powder X-ray diffraction, scanning electron microscopy and dilatometry, respectively. A maximum solid solution limit of 5% Sr in the A-site of SryLa1−yNb1-xVxO4-δ samples is observed for a vanadium content of x = 0.25, while further increases in the Sr or vanadium contents lead to the presence of Sr3(VO4)2 as a secondary phase. This acceptor dopant content of 5%Sr in the current scheelite material exceeds that possible in the parent vanadium-free fergusonite SryLa1−yNbO4-δ material by a factor of 5. All Sr doped scheelite materials show linear thermal expansion behaviour, successfully avoiding the scheelite to fergusonite structural phase change during thermal cycling. The average grain size is shown to be increased by increasing vanadium content. In humid conditions, all phase pure samples show predominantly proton conductivity at lower temperatures, while p-type conductivity is noted at higher temperatures under dry oxidising conditions. In the low temperature range, the Sr0.05La0.95Nb0.75V0.25O4-δ sample, containing the largest acceptor dopant concentration, exhibits slightly higher bulk and specific grain boundary conductivities in comparison to other phase pure compositions.

Effect of Cr dopant on the structural, magnetic and dielectric properties of Cu-Zn nanoferrites

Chromium substituted copper zinc ferrite of spinel crystal structure was synthesized in the form of nanoparticles using citrate nitrate combustion method. Phase composition, structure, magnetic and dielectric parameters were depicted by XRD, FTIR, HRTEM, VSM and dielectric measurements. Demeanor of magnetization has been elucidated on the basis of Neel's model of magnetic interactions and Yafet-Kittel angle existence. Dispersion of dielectric parameters proclaims the normal behavior of ferrites. Cole–Cole plot manifests the role of both grain boundary and bulk grain in conduction mechanism. The substitution of Cr3+ ions plays a decisive role in amending structural, magnetic and dielectric features of copper zinc nanoferrites. The optimum properties of the nanoferrite Cu0.8Zn0.2Cr0.02Fe1.98O4 make it primness for applications; especially data storage and magneto-electronic devices.

Finite Element Analysis of Cylindrical Inclusions in Polycrystalline Nickel Alloys

Inspired by nanotubes, a 3D finite element model was developed to simulate the influence of cylindrical inclusions on the polycrystalline mechanical behavior of Nickel alloys. A dislocation based strain hardening model, constructed in the so-called Kocks–Mecking framework, is used as the main strategy for the constitutive modeling of individual bulk grains. To determine the influence of the inclusions distribution, the direction of applied load and the size of the matrix phase on the inelastic stress–strain distribution, the digital microstructure code DREAM.3D was coupled to ABAQUS[Formula: see text] finite element code through a MatLab[Formula: see text] program. Four affordable computational representative volume elements (RVEs) meshes of two different edge sizes and two different inclusion distributions were tested to investigate the relation between micro and macro deformation and stress variables. The virtual specimens, subjected to continuous monotonic strain loading conditions, were constrained with random periodic boundary conditions. The difference in crystallographic orientation, which evolves in the process of straining, and the incompatibility of deformation between neighboring grains were accounted for by the introduction of single crystal averaged Taylor factors, single crystal Young’s modulus, single phase elastic modulus and the evolution of geometrically necessary dislocation density. The effects of single crystal Young’s modulus, inclusion distribution and direction of the applied load upon the aggregate local response are clearly observed. Results demonstrate a strong dependence of flow stress and plastic strain on phase type, Young’s modulus values and direction of the applied load, but slightly on matrix grain size. The stress–strain curve extension and the variation in the elastic limit of the individual inclusions depend on the inclusion-matrix Young’s modulus difference and applied load direction. The difference in curve extension and the difference in elastic limit decrease as the Young’s modulus of the single crystal inclusion approach the Young’s modulus of the matrix majoritary phase, while the resistance to flow increases when the applied load is perpendicular to the inclusion longitudinal axis.

Oxygen isotope enrichment in rice (Oryza sativa L.) grain organic matter captures signature of relative humidity

The oxygen isotopic composition (δ18O) of plant organic matter (OM) is primarily governed by the δ18O of source water (δ18OSW) and climatic factor of relative humidity (RH). Among the cereals, the growth of rice plants is critically dependent on the water availability in the growth-environment. In the present study, we investigated the sensitivity of δ18O in the bulk organic matter of rice grains to RH of their growth-environment. Our experimental setup consisted of both glasshouse and field experiments, where eight genotypes were grown at RH levels ranging from 67% to 87%. The δ18O measured in bulk grain OM and source water was used to calculate the net oxygen isotopic enrichment (Δ18OOM). Regression analysis of Δ18OOM with RH demonstrated a significant relationship (r2 = 0.96; p < 0.0001), thereby implying that the isotopic signature of evaporative conditions gets recorded in the rice grain OM. In addition, our study involved a separate experiment that monitored the degree of oxygen isotope enrichment in water samples extracted from different parts of the rice plant. For this purpose, we sampled four of the above eight genotypes along with three other rice genotypes that were grown in both open cultivation fields and glasshouse. Water present in the culms, leaves, and grains were extracted quantitatively. Isotopic analyses revealed progressive 18O enrichment of the water in the culms and leaves and intermediate enrichment values of that in the grains. Based on the isotope data, we validated mechanistic models for prediction of δ18O of the leaf water and that of the plant carbohydrates. The model predictions were in close agreement with the experimental observations. The study provides insights into the rice plant’s oxygen isotope systematics that build the foundation for future applications of the stable isotope technique to study the interactions between rice and environment.

A comparative study of primary damage state in Ni and NiCr/NiFe with a model grain boundary structure

The interaction of displacement cascades with atomic interfaces, specifically grain boundaries (GBs) is of great importance in design and development of radical advanced Ni-based super alloys with self-healing capabilities for future fission reactors. In this work, pure Ni and NiCr (with 5, 10, 15 and 20 at.% Cr content) and NiFe (with 5, 10 and 15 at.% Fe content) alloys with symmetric tilt Σ5[1 0 0](0 1¯ 3)θ = 37° GBs are used as model structures to study the influence of Cr and Fe on the primary and long-term radiation response of Ni-based alloys with microstructures. Molecular dynamics is used in simulating the primary damage event and the continuous ion bombardments in NiCr/NiFe structures to qualitatively represent the severe irradiation condition expected in next-generation fission reactors. In general, we observe that the GBs in “pristine” and “damaged” (∼after being continuously bombarded) forms preferentially absorb radiation-produced interstitials both Ni and Cr/Fe, over vacancies which results in accumulation and clustering of immobile vacancies in the grain interiors. The presence of Cr and Fe does not significantly affect the sink properties of our model GB and therefore, does not change the clustering behavior of excess vacancies in the bulk grains on picosecond (ps) timescale. The only evident phenomenon is a notable variation in the energetics and probably kinetics of point defects that slightly changes the evolution pattern of displacement cascades in the damage regions on ps timescale. The GB roughening incident is also observed in both Ni and NiFe/NiCr alloys during irradiation. In alloys with GBs, we also analyzed changes in the short range order parameter of irradiated structures. Our results indicate that in the primary event of radiation damage, a single bombardment is not enough to induce any trend in ordering or disordering of Cr and Fe solutes; in a prolonged irradiation, on the other hand, MD results reveal a very weak tendency of solutes to diffuse toward each other, although we did not observe any obvious Cr or Fe clustering in any of the performed displacement cascade simulations. Eventually, on ps timescale, we conclude that the Cr and Fe solutes contribute in enhancement of radiation tolerance of binary alloys in similar ways as Ni atoms do; but further details about the diffusion mechanisms of solutes on a longer timescale is essentially required to have more accurate predictions from a radiation damage perspective.

Ionic conductivities and high resolution microscopic evaluation of grain and grain boundaries of cerium-based codoped solid electrolytes

Doped CeGdO and codoped CeGdOSmO compositions were synthesized, giving rise to nanoparticulate powders. Ionic conductivities at bulk and grain boundaries of the sintered samples were determined, exhibiting increased conductivity in the samaria-codoped samples. Scanning electron microscopy (SEM) showed a significant reduction in the grain size of samaria-codoped electrolytes. This reduced grain size of the codoped samples caused a reduction in Schottky barrier height, increasing oxygen vacancy concentration in the space-charge layer of the grain boundary and culminating in greater ionic conductivity in the boundary region. For the gadolinium doped samples, high resolution transmission electron microscopy images at grains showed the presence of large cluster of defects (nanodomains), hindering the movement of charge carriers and reducing ionic conductivity. However, the samaria-codoped system displayed better homogeneity at atomic level, resulting in reduced oxygen vacancy ordering and, consequently, smaller nanodomains and higher bulk (grain) conductivity. The reduced grain sizes and smaller nanodomains caused by codoping favor the ionic conductivity of ceria-based ceramics, doped with gadolinia and codoped with samaria.

EBSD analysis of surface and bulk microstructure evolution during interrupted tensile testing of a Fe-19Cr-12Ni alloy

The microstructure evolution in both surface and bulk grains in a pure Fe-19Cr-12Ni alloy has been analyzed using electron backscatter diffraction after tensile testing interrupted at different strains. Surface grains were studied during in situ tensile testing performed in a scanning electron microscope, whereas bulk grains were studied after conventional tensile testing. The evolution of the deformation structure in surface and bulk grains displays a strong resemblance but the strain needed to obtain a similar deformation structure is lower in the case of surface grains. Both slip and twinning are observed to be important deformation mechanisms, whereas deformation-induced martensite formation is of minor importance. Since the stacking fault energy (SFE) is low, ~17 mJ/m2, dynamic recovery by cross slip of un-dissociated dislocations is unfavorable. This reduces the annihilation of dislocations which in turn leads to a significant increase of low angle boundaries with increasing strain. The low SFE also favors formation of deformation twins which reduces the slip distance, leading to a hardening similar to the Hall-Petch relation. The combination of a low ability for cross-slip and a reduced slip distance caused by twinning is concluded to be the main reason for maintaining a high strain-hardening rate up to strains close to necking.

Signal or noise? Isolating grain size effects on Nd and Sr isotope variability in Indus delta sediment provenance

Radiogenic elements, such as neodymium (Nd) and strontium (Sr), are commonly used to decipher the provenance and weathering histories of bulk siliciclastic sediments worldwide, although increasing evidence for diagenetic and sediment transport-driven bias of isotope signatures calls into question the utility of bulk isotope compositions as effective tools. This study evaluates grain size-dependence and variability of Nd and Sr compositions in the Indus delta of Pakistan, documenting both a significant isotopic evolution and coarsening upward sequence during the last deglaciation (~15 ka). Grain size analysis, trace element geochemistry, and Nd and Sr geochemistry are determined for bulk and separate grain size fractions (<63 μm, 63–125 μm, 125–250 μm, >250 μm) from four core sampling sites with similar provenance. Isotopic compositions are controlled by grain size distribution, in turn variably controlled by size fraction mineralogy. Fine-grained bulk sediment Nd isotope compositions are primarily dictated by the finest (<125 μm) sediments enriched in Nd-bearing monazite and allanite, with coarser bulk sediments influenced by mica. The most abundant grain size fraction drives bulk sediment Sr isotope compositions, with the finest grain size fractions indicating strong control by potassium feldspar, mica, epidote, and/or volcanogenic clay minerals. Over the last 15 k.y., resolvable provenance-driven trends are confidently identified in Nd isotope compositions. Long-term trends remain consistent with previous findings although the isotopic shift in delta compositions must be less than previously envisaged (~4 vs. 0.69–1.91 εNd units). Although considerable variability is observed in bulk Sr isotope compositions, <63 μm and 63–125 μm fraction 87Sr/86Sr compositions evolve in parallel through time and show fractionation by ~0.005–0.01 as a result of grain size. Within the isotopically diverse Indus drainage system, bulk isotopic compositions are estimated to deviate on average no than ±1.04 εNd units and ±0.0099 for 87Sr/86Sr values for any sediment as a result of mineralogy, grain size distribution, and analytical error. Isotopic excursions beyond these uncertainties can be unambiguously assigned to either a change in upstream provenance and/or chemical weathering.

Crystal growth and characterization of Au3+ ion irradiated 2-amino-5-nitropyridinium hydrogen oxalate (2A5NPHO)

ABSTRACT2-amino-5-nitropyridinium hydrogen oxalate (2A5NPHO) was grown using slow evaporation and bulk crystal of 2A5NPHO was harvested from Assembled Temperature Reduction (ATR) method. Cut and polished crystal was irradiated using Au3+ ion with various fluences. Electronic loss, nuclear energy loss and penetration depth were calculated using SRIM software. It was observed in X- ray pattern that intensity of peak was reduced. Intensity of peak decreased with increase of ion fluencies from 1013 ions/cm2 to 1014 ions/cm2. Optical properties were measured using UV-Vis spectrometer. The increase of absorption was due to excited electrons which were formed by vacancies and formation of additional defects centres. Energy band gap of irradiated crystals increased with increase of ion fluence. Energy band gap of irradiated crystals were 3.39 eV, 3.42 eV, and 3.4 eV for 1013 ions/cm2, 5 × 1013 ions/cm2 and 1014 ions/cm2 respectively and increase of band gap was due to the increase of forbidden gap. Microhardness was calculated using Vicker's Hardness tester. Increase of microhardness in irradiation crystal was due to increase of high density lattice defects produced by Au3+ of 10.8 MeV. Electrical property was calculated using dielectric constant. Increase of dielectric constant was due to large polarization which caused by disorderness and rich defects in the crystalline surface. Decrease of intensity peak in fluorescence was due to transition of excited electron to intermediated energy levels from excited state which converted into vibrational energy of lattice atoms (phonon). Morphology of irradiated crystal was seen using scanning electron microscope (SEM). It was observed from the SEM image that surface of crystal was heavily damaged. It was also noticed that the thermal stability of the irradiated single crystal increased with increase of ion fluences. Impedance of irradiated crystal was measured. The bulk resistance and grain boundary resistance also were calculated.