Related Physical Properties Research Articles

Cover Crops as Affecting Soil Chemical and Physical Properties and Development of Upland Rice and Soybean Cultivated in Rotation

Cover crops can provide changes in soil chemical and physical properties, which could allow a sustainable development of soybean and upland rice rotation in Brazilian Cerrado. The objective of this study was to determine the effects of cover crops (cultivated in the offseason) in the soybean-upland rice rotation (cultivated in the summer season) on the soil chemical and physical properties, yield components and grain yield of the cash crops. The experimental design was a randomized block design in factorial scheme 4×2 with six replications. Treatments were composed by four cover crops: fallow, millet (Pennisetum glaucum)+Crotalaria ochroleuca, millet+pigeon pea (Cajanus cajans), and millet+pigeon pea+Urochola ruziziensis in the offseason with one or two cycles of cover crops, with rice (Oryza sativa) or soybean (Glycine max) in the summer season. Cover crops alone provided no changes in soil chemical properties. However, the rotation cover crops/cash crops/cover crops/cash crops reduced pH, Al and H+Al and increased Ca, Mg, K and Fe contents in the soil. The cover crops millet+pigeon pea and millet+pigeon pea+U. ruziziensis improved soil physical properties in relation to fallow, especially in the 0–0.10m soil layer. In spite of the improvement of the soil physical properties after two years of rotation with cover crops and cash crops, the soil physical quality was still below the recommended level, showing values of macroporosity, S index and soil aeration capacity lower than 0.10 m3/m3, 0.035 and 0.34, respectively. Upland rice production was higher under mixtures of cover crops than under fallow, mainly because of soil physical changes done by these mixtures of cover crops. Soybean grain yield was similar under all cover crops tested, but was higher after the rotation cover crops/upland rice/cover crops than after only one cycle of cover crops.

Ion dopants tuning the interband electronic structure for huge saturated ferroelectric polarization in bismuth ferrite films

Bismuth ferrite (BiFeO3, BFO) as a prototype multiferroic has been extensively studied in past years; however, there are several key issues not to be clearly expressed. Especially, the relationship of structure and physical properties still remains obscure. In this case, the interband electronic structure of BFO was elaborately manipulated by appropriation dopants of Ni and Gd to realize the huge saturated ferroelectric polarization in the polycrystalline films. For instance, a huge saturated polarization PS of 96 μC/cm2 and remnant polarization Pr of 91 μC/cm2 were achieved in Bi0.925Gd0.075Fe0.95Ni0.05O3 film. The results and analysis show that the alteration in the interband electronic structure and the improvement of morphology derived from the ion doping effect indeed play key roles on the improved ferroelectric property of the doped BFO films. The decreased leakage current density and thereby the enhanced ferroelectric polarization in the doped BFO films should be attributed to the decrease in both Fermi level and Urbach energy closely related with the defects, as well as the improved surface uniformity and compactness of the films. Finally, the mechanism and relationship of structure and physical properties in BFO were systemically analyzed and discussed.

Physical property characterization of quaternary sediments in the vicinity of the paleo-Seomjin River of the continental shelf of the South Sea, Korea

Thirty-two core samples were collected from the continental shelf area of the South Sea, Korea. They have been used to characterize physical properties in relation to sedimentary units (interpreted from seismic and core data) and to interpret physical property variation as a function of burial depth. The physical property data were readily classified into sedimentary units: Units S1, S2, S3, S4, and S5, in descending order. The variations in physical properties reflect well the relative characteristics of sedimentary units (equivalent to seismic units). Moreover, the relationships between physical properties are well grouped by each sedimentary unit. In addition, the distributions of physical properties match well with the grain size distribution and bathymetry of the study area. In particular, the lithology (e.g., grain size) plays an important role in the variation of physical properties. These results suggest that the physical properties of these sediments are mainly controlled by depositional processes in the vicinity of the paleo-Seomjin River, and that sea-level change specifically was a dominant sedimentary processes in the study area during the Quaternary. In particular, the physical properties of Unit S2 do not show transitional characteristics between Units S1 and S3, although it belongs to the transition zone in sequence order. This finding is attributed to the fact that compared with the sediments of Units S1 and S3, Unit S2 is composed of more coarse-grained sediments with abundant shell fragments.

Optimal modality selection in external beam radiotherapy

The goal in external beam radiotherapy (EBRT) for cancer is to maximize damage to the tumour while limiting toxic effects on the organs-at-risk. EBRT can be delivered via different modalities such as photons, protons and neutrons. The choice of an optimal modality depends on the anatomy of the irradiated area and the relative physical and biological properties of the modalities under consideration. There is no single universally dominant modality. We present the first-ever mathematical formulation of the optimal modality selection problem. We show that this problem can be tackled by solving the Karush-Kuhn-Tucker conditions of optimality, which reduce to an analytically tractable quartic equation. We perform numerical experiments to gain insights into the effect of biological and physical properties on the choice of an optimal modality or combination of modalities.

Photoacoustic response of a transmission photoacoustic configuration for two-layer samples with thermal memory

In this paper, the models of surface temperature variations have been derived. Based on these models, photoacoustic (PA) response has been commented for transmission PA setup configurations of two-layer optically transparent samples, including the impact of finite heat propagation velocity through both layers (thermal memory) and the existence of volume absorption in both layers. By analyzing the derived model it has been shown that many parameters influence the photoacoustic response. Based on the derived model, some approximations have been discussed in order to enable the development of more accurate inverse solutions of photoacoustic problem, and the estimation of optical, thermal and other related physical properties of versatile materials. By using specific two-layer structure that consist of aluminum sample coated with layer of color dye, used in some photoacoustic experimental investigations, the influence of thermal memory properties of either the sample or the coating has been discussed.

Effect of defect states and oxygen vacancies on optical transitions due to Co2+ substitution in CeO2

CeO2 has cubic fluorite structure which is modified due to oxygen content as well as external substituents. The oxidation state of Ce plays an important role in strain and related physical properties. Ce3+ being larger in size than the Ce4+ ion, one expects a change in band structure due to changes in bond length; substitution of Ce4+ by Co2+ in sol–gel prepared, homogeneous, single-phase Ce1−xCoxO2 (x ≤ 10) nanopowders. The lower valence states of Co2+ induces oxygen vacancies which transforms some Ce4+ to Ce3+. A careful study of oxygen vacancies, strain, bond length and related band structure changes, have been targeted in this study. The possibility of phonon participation in electronic transition has been discussed using Tauc plot. Ce3+ forms defect states, between valence and conduction bands. Lattice parameters decrease, but strain increases with substitution.

Ultrasonic spray-freeze drying of partially purified microbial transglutaminase

Ultrasonic spray-freeze drying (USFD) was evaluated to produce partially purified microbial transglutaminase (mTGase) powder, and the effects of the process conditions (a nozzle frequency of 48–120kHz and a flow rate of 2–8ml/min) on enzyme activity and particle size were determined. Furthermore, the relative activity changes at each step of USFD and the behavior of the dried enzyme at extreme pH levels, high temperature and presence of the metal ions were investigated. Additionally, the final product produced by USFD and the powder produced by conventional freeze drying (CFD) were compared in terms of relative activities and physical properties. The results showed that atomizing conditions affected the particle size and, hence the enzyme activity. The enzyme activity was enhanced by ultrasonic atomizing at all conditions while most of the activity loss occurred in the drying step. The USFD provided higher enzyme activity, smaller particle size, better particle morphology and better reconstitution properties than CFD, which are explained by the ultrasonic atomizing and accelerated freezing steps of USFD. Also, the USFD sample preserved its stability in tough conditions, such as extreme pH levels, high temperature and the presence of metal ions better than the CFD counterpart.

Secondary carbides in high chromium cast irons: An alternative approach to their morphological and spatial distribution characterization

Secondary carbides precipitated in high chromium cast irons during thermal treatments were characterized by means of different characterization techniques, including scanning electron microscopy, energy dispersive X-ray spectroscopy, electron backscattered diffraction and a combination of chemical etching with confocal scanning laser microscopy. This set of techniques provides a full morphological, chemical and crystallographic description of the analysed phases.This work evaluated different methods for optimizing the image acquisition for a further image analysis (IA) based on the threshold binarization. Finally, the carbide size, distribution and morphology were determined after IA of the images acquired by aforementioned characterization techniques. Although the different techniques report some dispersion in the value for the average particle size, the particle inter-spacing and aspect ratio meet within the error value. The proposed characterization methodology provides statistically reliable data for a further evaluation of related physical properties in composites.

Uncertainty analysis of axial temperature and Seebeck coefficient measurements.

Experimental investigations of solid materials at elevated temperatures rely on the optimized thermal design of the measurement system, as radiation becomes a predominant source of heat loss which can lead to large uncertainty in measured temperature and related physical properties of a test sample. Advancements in surface temperature measurements have reduced thermal losses arising from the cold-finger effect using axially inserted thermocouples and from radiation using shields or other thermal guards. The leading technology for temperature sensing at temperatures up to ∼900 °C makes use of these design features for measuring thermopower, yet uncertainty analysis estimation of this technique is not known. This work makes use of finite element modeling to determine spatial temperature distributions to obtain the upper limit of confidence expected for the axially inserted thermocouple approach when a heated radiation shield is incorporated into the design. Using an axially inserted thermocouple to measure the sample surface temperature, the temperature variations across the sample hot and cold surfaces at 900 °C for a temperature drop of 0, 5, and 10 °C are calculated to be as low as 0.02, 0.21, and 0.41 °C, respectively, when a heated radiation shield is employed. Uniform temperature distribution on the thermocouple cross-wire geometry indicates that the axial thermocouple measurement design is indeed effective for suppressing the cold-finger effect. Using a heated radiation shield is found to significantly reduce the temperature gradient across the thermocouples.

The surface treatment of dental ceramics: an overview

This review proposes to present some aspects of dental ceramics surface treatments, which involve the related physical and mechanical properties, as well as new technologies. The correct cementation of prosthetic restoration is essential for clinical success. However, the adhesive technique is a very recent procedure and clinicians should have a more detailed knowledge about the technique and related materials so that they can use them in their day-to-day clinical practice. Information about the the principles, indications and contraindications of adhesive cementation technique were obtained from the literature. The studies indicate that the adhesive system seems to be a valid option for fixed prosthesis cementation, since it has several advantages over conventional cementation method, especially in all-ceramic restorations. In clinical practice, the clinician should always keep in mind the characteristics of the material they are working with, so that they can select the best technique and the best cement for each clinical situation. Although more research is required in this field, there are no scientific reasons to contraindicate in routine practice.

Experimental Investigation on CO2 Injection in Block M

The purpose of this report was to perform an experimental evaluation of enhanced oil recovery (EOR) using CO2 injection. A slim tube test and PVT experiment are used to determine the minimum miscibility pressure as well as a few related physical properties. Combined with a long core displacement experiment and nuclear magnetic resonance, CO2 flooding and CO2-water alternate flooding are simulated, and the displacement efficiency of different types of pores is evaluated. The results indicate that the minimum miscibility pressure is 32.6 MPa, and the CO2 flooding is at near-miscible conditions at the current formation pressure. The CO2 solubility of crude oil is large, and the crude oil has a strong expansion ability after the CO2 injection, which is beneficial for improving the recovery of CO2. The EOR of CO2-water alternate flooding is 3.97% higher than that of continuous CO2 flooding, and the EOR in the small and middle pores in the CO2-water alternate flooding is clearly higher. These results will be relevant for the future development of Block M.

An Unusual Phase Transition Driven by Vibrational Entropy Changes in a Hybrid Organic–Inorganic Perovskite

The driving forces for the phase transitions of ABX3 hybrid organic-inorganic perovskites have been limited to the octahedral tilting, order-disorder, and displacement. Now, a complex structural phase transition has been explored in a HOIP, [CH3 NH3 ][Mn(N3 )3 ], based on structural characterizations and ab initio lattice dynamics calculations. This unusual first-order phase transition between two ordered phases at about 265 K is primarily driven by changes in the collective atomic vibrations of the whole lattice, along with concurrent molecular displacements and an unusual octahedral tilting. A significant entropy difference (4.35 J K-1 mol-1 ) is observed between the low- and high-temperature structures induced by such atomic vibrations, which plays a main role in driving the transition. This finding offers an alternative pathway for designing new ferroic phase transitions and related physical properties in HOIPs and other hybrid crystals.

An Unusual Phase Transition Driven by Vibrational Entropy Changes in a Hybrid Organic–Inorganic Perovskite

AbstractThe driving forces for the phase transitions of ABX3 hybrid organic–inorganic perovskites have been limited to the octahedral tilting, order–disorder, and displacement. Now, a complex structural phase transition has been explored in a HOIP, [CH3NH3][Mn(N3)3], based on structural characterizations and ab initio lattice dynamics calculations. This unusual first‐order phase transition between two ordered phases at about 265 K is primarily driven by changes in the collective atomic vibrations of the whole lattice, along with concurrent molecular displacements and an unusual octahedral tilting. A significant entropy difference (4.35 J K−1 mol−1) is observed between the low‐ and high‐temperature structures induced by such atomic vibrations, which plays a main role in driving the transition. This finding offers an alternative pathway for designing new ferroic phase transitions and related physical properties in HOIPs and other hybrid crystals.

Physical and mechanical property relationships of a shallow intrusion and volcanic host rock, Pinnacle Ridge, Mt. Ruapehu, New Zealand

Shallow magmatic intrusions are prevalent in volcanic settings worldwide. Understanding how these intrusions interact and influence their volcanic host rocks is therefore relevant to many engineering geology, geothermal, and volcanological applications. In this study, we present the most comprehensive dataset for a shallow intrusion and its host rock in a volcanic setting to date, detailing the mechanical and physical properties of volcanic rocks from Pinnacle Ridge, Mt. Ruapehu, New Zealand. Based on the geomechanical properties of 194 measured samples, we identify seven geotechnical units: (1) unaltered dense coherent lava, (2) altered dense coherent lava, (3) unaltered brecciated lava margin, (4) altered brecciated lava margin, (5) unaltered intrusion, (6) altered intrusion, and (7) hydrothermal veining. We detail the mineralogy (andesite compositions ranging from primary to an advanced argillic alteration assemblage), porosity (0.7–31%), permeability (10−21–10−12 m2), elastic wave velocities (1994–5615 m/s), uniaxial compressive strength (1–332 MPa) of these geotechnical units. Our laboratory analyses indicate that primary lithology is the predominant control on the physical and mechanical properties of the geotechnical units. Additionally, the data suggest that there is a correlation between distance to the largest intrusion; this is particularly evident for the measurements on the brecciated lava margin samples. Towards the largest intrusion, this breccia shows decreasing porosity (30.92 to 5.49%) and permeability (10−12 to 10−17 m2) and increasing elastic wave velocities (1994 to 4157 m/s) and uniaxial compressive strength (3 to 61 MPa). Thin-section analysis suggests that these correlations are due to mineral precipitation within fractures and pores in the brecciated lava margins. These correlations with distance to the largest intrusion are not shared by the altered intrusions or dense coherent lavas. We suggest that the high primary permeability of the unaltered breccia facilitated efficient hydrothermal fluid circulation and mineral precipitation adjacent to the intrusion. The other geotechnical units are less affected because hydrothermal fluid flow, alteration, and mineral precipitation were limited due to low initial permeability (10−21–10−16 m2). Our study shows that the initial properties of the host rock (i.e. porosity and permeability) control the extent of hydrothermal alteration and the susceptibility to modifications of rock geomechanical properties. Modifications to porosity and permeability can influence edifice-scale behaviour; for example, a reduction in permeability can result in pore pressure augmentation, which exerts a primary control on volcanic slope stability, seismicity, and eruptive behaviour. This study provides the most comprehensive and complete geomechanical properties data suite on a shallow intrusion in volcanic host rock to date and will support monitoring and modelling of volcanic hazards associated with shallow igneous intrusions.

In silico cloning and comparative analysis of NAD1 gene in three common human parasites

To in silico clone the NAD1 gene of three common parasites and analyze their bioinformatics, so as to lay the foundation for further research on the NAD gene. By using the in silico cloning method, the full length cDNA (s) of NAD 1 genes of Clonorchis sinensis, Ascaris lumbricoides and Schistosoma japonicum were got, then their physical and chemical properties, compositions of amino acids, subcellular localizations, binary and ternary structures were contrastively analyzed. The three kinds of NAD1 proteins were similar in the relative molecular weight, subcellular localization, and physical and chemical properties. The NAD1 proteins were highly similar in binary and ternary structures of A. lumbricoides and S. japonicum. The phylogenetic analysis showed that C. sinensis, A. lumbricoides and S. japonicum belonged to the different evolutionary branches with a certain of genetic distance. The three NAD1 genes got from C. sinensis, A. lumbricoides and S. japonicum by in silico cloning belong to the same gene of different species, which can be widely used in the researches of heritable variation of parasites.

The effect of architecture on the mechanical properties of cellular structures based on the IWP minimal surface

Abstract

Co-gasification of Corn and Coconut Residues in Downdraft Gasifier

Reliance on a single biomass to generate electrical power can cause disruption due to the inconsistencies in the supply of biomass feedstock. Co-gasification of different biomass can mitigate the problem of inconsistence biomass supply. The aim of this study to investigate thermochemical properties of corn residues (CR) and coconut shells (CS) and syngas performance produced from co-gasification of CR and CS. Biomass materials were characterized in order to understand their physical properties in relation to thermochemical conversion. Co-gasification of CR and CS was carried out in externally heated downdraft gasifier at CR:CS ratio of 50:50, 40:60 and 20: 80. CO composition obtained from blended feedstock is higher as compared to the without blended feedstock. The CO2 and CH4 concentration were increased as CS proportion increased in blend. Biomass with higher moisture content plays important role in the H2 production due to the supercritical water gasification. The blending ratio of CR and CS at 20:80 had a positive synergetic effect as evident by increase in the gas composition for CO, CH4 and H2. It is concluded that co-gasification results of CR and CS is practical and can be considered to complement each other.

Physical and optical investigation of lutetium-sodium-borate glasses

Physical and optical properties of lutetium sodium borate glasses have been examined. A series of glass samples with the different chemical composition xLu2O3:20Na2O:(80-x)B2O3 (where x = 5, 10, 15 and 20 mol%) were successfully fabricated by a melt quenching technique and their properties were investigated through various techniques include density, absorption, and X-ray diffraction. The amorphous nature was confirmed by the presence of a broad hump in the XRD pattern. The relevance parameters related physical and optical properties have been calculated and discussed.

Structure and Phase Transformation in the Giant Magnetostriction Laves-Phase SmFe2.

As one class of the most important intermetallic compounds, the binary Laves-phase is well-known for its abundant magnetic properties. Samarium-iron alloy system SmFe2 is a prototypical Laves compound that shows strong negative magnetostriction but relatively weak magnetocrystalline anisotropy. SmFe2 has been identified as a cubic Fd3̅m structure at room temperature; however, the cubic symmetry, in principle, does not match the spontaneous magnetization along the [111]cubic direction. Here we studied the crystal structure of SmFe2 by high-resolution synchrotron X-ray powder diffraction, X-ray total scattering, and selected-area electron diffraction methods. SmFe2 is found to adopt a centrosymmetric trigonal R3̅m structure at room temperature, which transforms to an orthorhombic Imma structure at 200 K. This transition is in agreement with the changes of easy magnetization direction from [111]cubic to [110]cubic direction and is further evidenced by the inflection of thermal expansion behavior, the sharp decline of the magnetic susceptibility in the field-cooling-zero field-cooling curve, and the anomaly in the specific heat capacity measurement. The revised structure and phase transformation of SmFe2 could be useful to understand the magnetostriction and related physical properties of other RM2-type pseudocubic Laves-phase intermetallic compounds.

Preparation and characterization of magnetic Fe3O4–chitosan nanoparticles for cellulase immobilization

Cellulase immobilization is an important issue for cellulose hydrolysis in bioethanol production. In this study, Fe3O4 nanoparticles were synthesized using a coprecipitation method and were coated with chitosan. Glutaraldehyde was used as cross-linking reagent for cellulase immobilization. The morphology, structure, and related physical and chemical properties of the supports were studied by X-ray diffraction, a physical property measurement system, Fourier transform infrared spectroscopy, and Transmission electron microscopy. Response surface methodology was used to determine the optimal cellulase loading efficiency (LE) and standard recovery ratio (RR). The verification tests show the immobilized particles had an LE of 99.6% and an RR value of 68.5%. It was found that immobilized cellulase had a wider range of adaptability to hydrolysis pH and temperature when compared with free cellulase. Five hydrolysis experiments demonstrated effective hydrolysis using immobilized cellulase while maintaining on average 80% of the free cellulase’s activity.