Growth Of Stable Phase Research Articles

Development status of coal industries in the worlds major coal-producing countries

The global coal industry has changed significantly in recent years. In this paper we analyse the coal production and consumption, imports and exports, and coal prices in China and other major coal-producing countries during the past four decades. The analysis shows that global coal production and consumption have declined over the last three years, in striking contrast to the continuous growth for most of the past 35 years. Australia, Indonesia, and Russia have become the world's major coal providers, while China, India, and the USA, and Germany are the major coal consumers. The world's, and China's, coal industry can be classified into four stages of development: the stable growth phase, stable phase, rapid growth phase, and high-quality phase. Coal prices rose in the world's four major coal markets in 2016 after four consecutive years of falling prices. The elimination of overcapacity and production-optimizing operations in China could assist in achieving a demand and supply balance.

1 H NMR-based process understanding and biochemical marker identification methodology for monitoring CHO cell culture process during commercial-scale manufacturing.

Controlling the process of CHO cell fed-batch culture is critical for biologics quality control. However, the biological complexity of cells has hampered the reliable process understanding for industrial manufacturing. In this study, a workflow was developed for the consistency monitoring and biochemical marker identification of the commercial-scale CHO cell culture process through 1 H NMR assisted with multivariate data analysis (MVDA). Firstly, a total of 63 metabolites were identified in this study object in 1 H NMR spectra of the CHO cell-free supernatants. Secondly, multivariate statistical process control (MSPC) charts were used to evaluate process consistency. According to MSPC charts, the batch-to-batch quality consistency was high, indicating the CHO cell culture process at the commercial scale was well-controlled and stable. Then, the biochemical marker identification was provided through orthogonal partial least square discriminant analysis (OPLS-DA) based S-line plots during the cell logarithmic expansion, stable growth, and decline phases. Identified biochemical markers of the three cell growth phases were as follows: L-glutamine, pyroglutamic acid, 4-hydroxyproline, choline, glucose, lactate, alanine, and proline were of the logarithmic growth phase; isoleucine, leucine, valine, acetate, and alanine were of the stable growth phase; acetate, glycine, glycerin, and gluconic acid were of the cell decline phase. Additional potential metabolic pathways that might influence the cell culture phase transitions were demonstrated. The workflow proposed in this study demonstrates that the combination of MVDA tools and 1 H NMR technology is highly appealing to the research of the biomanufacturing process, and applies well to provide guidance in future work on consistency evaluation and biochemical marker monitoring of the production of other biologics.

Effect of Stress Ratio on Fatigue Crack Propagation Behavior of Single Crystal Superalloy

In order to study the impact of different stress ratio on the fatigue crack growth behavior of DD6 single crystal superalloy, the fatigue crack growth rate test of different stress ratio (R = 0.05, 0.2, 0.5, 0.6) at 530 °C was conducted, the influence of stress ratio on crack growth rate was studied, and the growth of crack extension rate was corrected by normalization method. The results show that the section includes the fatigue fracture section perpendicular to the load and an angle to the load. The flat section is the main section representing the crack extension. The oblique section is formed with the change of the crack extension load state, and its occurrence is related to the dispersion of (da/dN)−Δk data, reflecting the uniqueness of single crystal. The Paris formula better characterized the crack expansion behavior of DD6 alloy, and the stress is more sensitive than the crack growth rate in the early stable growth phase. Crack growth rate normalized characterization equation constructed under different stress ratios are predicted to be within the 1.3-fold dispersion band.

Differential Metabolomics Reveals Pathogenesis of Pestalotiopsis kenyana Causing Leaf Spot Disease of Zanthoxylum schinifolium.

Pepper leaf spot is a common disease of Zanthoxylum schinifolium. When it is serious, it directly affects the growth of Z. schinifolium, making the plant unable to blossom and bear fruit, which seriously restricts the development of the Z. schinifolium industry. Therefore, the pathogenic mechanism of leaf spots should be explored to provide a basis for a comprehensive understanding of the disease. Using liquid chromatography-mass spectrometry (LC-MS) technology combined with the data-dependent acquisition, the full spectrum analysis of pathogen mycelium samples was carried out. Partial least squares discriminant analysis (PLS-DA) was used to reveal the differences in metabolic patterns among different groups. Hierarchical clustering analysis (HCA) and PLS-DA were used to reveal the relationship between samples and metabolites, which reflected the metabolomics changes of Pestalotiopsis kenyana in the logarithmic growth phase of mycelia, the stable growth phase of mycelia, the massive spore stage, the induction culture conditions of PDA and Z. schinifolium leaves, and the possible pathogenic substances were selected for pathogenicity detection. PLS-DA had a strong predictive ability, indicating a clear analysis trend between different groups. The results of the metabolomics analysis showed that the differential metabolites of pathogenic bacteria were abundant at different stages and under different medium conditions, and the content of metabolites changed significantly. There were 3922 differential metabolites in nine groups under positive and negative ion modes, including lipids and lipid molecules, organic acids and their derivatives, organic heterocyclic compounds, organic oxygen compounds, carbohydrate polyketides, nucleosides, nucleotides, and analogs. The results of the pathogenicity test showed that the leaves treated with 3,5-dimethoxy benzoic acid, S-(5-adenosy)-l-homocysteine, 2-(1H-indol-3-yl) acetic acid, l-glutamic acid, and 2-(2-acetyl-3,5-dihydroxy phenyl) acetic acid showed different degrees of yellowish-brown lesions. This indicated that these substances may be related to the pathogenicity of P. kenyana, and the incidence was more serious when treated with 3,5-dimethoxybenzoic acid and S-(5-adenosy)- l -homocysteine. This study provides a basis for further analysis of differential metabolites and provides a theoretical reference for the prevention and treatment of Z. schinifolium leaf spot.

Improvement on bioleaching interfacial behavior between Bacillus mucilaginosus and vanadium-bearing shale by surfactant additive

Effects of surfactant SDS (Sodium Dodecyl Sulfate) on bacterial metabolism and vanadium leaching effect by Bacillus mucilaginosus (B. mucilaginosus) were explored. The results indicated that the bacteria adsorption dissolution effect and the organic acid dissolution effect could extract 29.12% and 35.21% of vanadium, respectively, which were 9.70% and 6.27% higher than those without SDS. SDS significantly enhanced the bacteria adsorption dissolution effect and the organic acid dissolution effect of B. mucilaginosus on vanadium-bearing shale, and the bacteria adsorption dissolution effect to improve the vanadium leaching efficiency was more remarkable. When the bioleaching time began to enter the bacteria stable growth phase and the stable pH phase, the EPS (Extracellular Polymeric Substances) concentration decreased by 73.1 mg/L and 68.2 mg/L under the action of SDS, respectively. However, the bacteria’s adsorbance on the mineral surface increased by 0.07 × 109 cells/mL and 0.13 × 109 cells/mL, respectively. The improvement on the bacteria adsorption dissolution effect with SDS was then revealed. SDS decreased the secretion of EPS, reduced the bacterial agglomeration, increased the adsorption capacity of bacteria, and thereby strengthened the dissolution effect. Furthermore, it was found that the H+ concentration in the leachate increased by 1.36 × 10−5 mol/L and 4.33 × 10−5 mol/L, respectively. The enhancement on the organic acid dissolution effect with SDS was also achieved. The increase of the organic carboxylic acid metabolites was beneficial to further remove the hydroxyl groups in the vanadium-bearing muscovite crystal lattice, and strengthen the destruction of the basic structure of silicon-oxygen tetrahedron and aluminum-oxygen octahedron, resulting in the release of vanadium.

Fermentation of ginkgo biloba kernel juice using Lactobacillus plantarum Y2 from the ginkgo peel: Fermentation characteristics and evolution of phenolic profiles, antioxidant activities in vitro, and volatile flavor compounds.

In this study, a strain of Lactobacillus plantarum Y2 was isolated from the ginkgo peel, and showed adequate adaptation to the ginkgo biloba kernel juice. After 48 h of fermentation, the number of viable cells in the stable growth phase was remained at 10.0 Log CFU/mL, while the content of total organic acid increased by 5.86%. Phenolic substances were significantly enriched, and the content of total phenolic substances increased by 9.72%, and the content of total flavonoids after fermentation exceeded 55.33 mg/L, which was 3.6 times that of the unfermented ginkgo juice. The total relative content of volatile flavor compounds increased by 125.48%, and 24 new volatile flavor substances were produced. The content of total sugar, total protein, and total free amino acid decreased to 44.85, 67.51, and 6.88%, respectively. Meanwhile, more than 82.25% of 4'-O-methylpyridoxine was degraded by lactic acid fermentation, and the final concentration in ginkgo biloba kernel juice was lower than 41.53 mg/L. In addition, the antioxidant and antibacterial activities of fermented ginkgo biloba kernel juice were significantly enhanced. These results showed that LAB fermentation could effectively improve the nutritional value and safety of ginkgo biloba kernel juice.

Long time-series measurements of high-frequency acoustic scattering from sea ice

Understanding relatively recent rapid changes in Arctic sea ice calls for extensive and continuous observations of the ice cover. Utilizing datasets obtained with 38, 70, and 200 kHz upward-looking transducers in the northeast Chukchi Sea, seasonal and year-to year changes in acoustic scattering were measured. Two complete annual cycles of scattering returns from the winters of 2017–2018 and 2018–2019 were analyzed. The initial effort in this research is constrained to the stable growth phase of sea ice in winter through the early melt onset the following spring. We also restricted our analysis to individual, minimally deformed ice floes to limit the variability caused by large-scale roughness. Results from this two-year analysis will be discussed along with their implications for future measurements and acoustic remote sensing of sea ice properties.

Measurements of high-frequency acoustic scattering from sea ice over one season in the Chukchi Sea

Understanding recent and rapid changes in Arctic sea ice calls for extensive and continuous observations of the ice cover. In-situ stations are spatially limited and satellite remote sensing techniques miss key variables of internal sea-ice structure. Utilizing a dataset obtained with 38, 70, and 200 kHz upward-looking transducers in the northeast Chukchi Sea, we take a first look at how acoustic scattering changes in response to environmental forcing. A complete annual cycle of narrow band scattering returns from the winter of 2017–2018 are investigated with comparisons to the overlying sea ice cover. The initial effort in this research is constrained to the stable growth phase of sea ice in winter through the early melt onset the following spring. Individual, minimally deformed ice floes are identified and tracked when located over the deployment sites. Additionally, atmospheric conditions relevant to changes in the internal properties of sea ice are cross-compared to scattering returns. Results from this preliminary analysis will guide pending Arctic fieldwork and the future development of inverse methods for acoustic remote sensing of sea ice.

The Influence of the Two-child Policy on Urbanization in China

Family planning has been China’s basic national policy since 1980, but it changed from a one-child policy to a two-child policy at the end of 2015 as which will further stimulate the rapid growth of China’s population and have a profound impact on the population structure and land use in China. Based on the forecast of total population change in national and provincial dimensions after the two -child policy, the paper forecasted the spatial pattern of China's population and provincial differentiation over the next 15 years, and discussed the far-reaching impact on the future urban and rural land use and planning. Conclusions as follows: the two-child policy will achieve rapid population growth in the next 5 years, then there will be a stable growth phase; the peak of China’s population increase will occur in 2030 with a total population of about 1.55 billion people，which will continuethe regional differentiation of urbanization，andurbanization level in southeastern region will remain generally higher than that of the northwest. In addition, population growth brings new demands in urban and rural construction land, therefore, more intensive use of land will be the inevitable choice for the future development for China.

Structural characteristics of gonadal development and hermaphroditic phenomenon in freshwater pearl mussel, Sinohyriopisis schlegelii (Hyriopisis schlegelii).

The period of gonads development was first studied from one to five years in the freshwater pearl mussel Hyriopisis schlegelii. It lasted for 36 months and was divided into three main stages: initiation of gonad formation, a stable growth phase, and a reproductive cell development phase. Each reproductive cycle consisted of five stages: proliferative stage (from late January to late February), growth stage (from late February to late March), maturation stage, spawning stage (from early April to late October) and recovery stage (from early November to late January). Interestingly, a hermaphroditic phenomenon was observed in this mussel for the first time, which appears during the development stage from 26 to 32 months. Male and female follicular tissues coexisted in hermaphrodite individuals with the male follicular tissue accounting for more than 90% of the whole gonad tissue. No hermaphroditic phenomenon was observed in matured gonad. We thus speculate that self-fertilization does not exist in H. schlegelii.

Algal biomass from the stable growth phase as a potential biosorbent for Pb(ii) removal from water

In this study, the effect of the growth phase on the Pb(ii) removal performance from water usingChlorellasp. QB-102 dry biomass was investigated.

Isolation and identification of a cellulolytic bacterium from the Tibetan pig's intestine and investigation of its cellulase production

article i nfo Background: The Tibetan pig is a pig breed with excellent grazing characteristics indigenous to the Qinghai-Tibet plateau in China. Under conditions of barn feeding, 90% of its diet consists of forage grass, which helps meet its nutritional needs. The present study aimed to isolate and identify a cellulolytic bacterium from the Tibetan pig's intestine and investigate cellulase production by this bacterium. The study purpose is to provide a basic theory for the research and development of herbivore characteristics and to identify a source of probiotics from the Tibetan pig. Results: A cellulolytic bacterium was isolated from a Tibetan pig's intestine and identified based on morphological, physiological, and biochemical characteristics as well as 16S rRNA analysis; it was designated Bacillus subtilis BY-2. Examination of its growth characteristics showed that its growth curve entered the logarithmic phase after 8-12 h and the stable growth phase being between 20 and 40 h. The best carbon source for fermentation was 1% corn flour, while 2% peptone and yeast powder compound were the best nitrogen sources. The initial pH during fermentation was 5.5, with 4% inoculum, resulting in a high and stable amount of enzyme in 24-48 h. Conclusions:TheisolatedBY-2strainrapidlygrewandproducedcellulase.WebelievethatBY-2cellulasecanhelp overcome the shortage of endogenous animal cellulase, improve the utilization rate of roughage, and provide strain sources for research on porcine probiotics.

Nucleation and growth of electrolytic gas bubbles under microgravity

The evolution of oxygen gas bubbles in potassium hydroxide solution is observed in situ under microgravity by a charge-coupled device camera, focusing on the wettability of a platinum electrode modified by thiol self-assembled monolayers. Single bubble measurements on the microwire electrode reveal a three-step growth process involving (1) the nucleation and formation of a supersaturated layer of dissolved gas followed by (2) a rapid growth phase depending on the gas diffusion process, and finally, (3) a stable growth phase where the growth rate is dominated by the bubble configuration depending on the contact angle. Moreover, correlation of multiple gas bubble observations with electrochemical data and surface coverage on the plate electrode reinforce the important role of wettability in determining bubble motion and energy consumption during electrolysis under microgravity.

Adapting the condensation and evaporation model to the study of kinetics of phase transformations in binary metal systems

A binary system in solid solution when is quenched at a temperature under the solubility limit, shows a structural instability that disappears when said system reaches equilibrium. In the process of reaching stability, a number of microstructural modifications or fluctuations in concentration occur, which tend to generate a decrease in the free energy of the system. Critical fluctuations arise, prompting the association of critical size clusters, from which the growth of the phases responsible for final equilibrium is produced. Such proposal falls completely under the nucleation and growth theory where the first stage --before critical fluctuation appears, occurs at nucleation, whereas the latter stage corresponds to growth and coalescence of the clusters. The evaporation and condensation theory has been adapted so that the process of phase transformation is simulated while considering different evolution pathways from solid solution to the phase of equilibrium. Because the nucleation phase is energetically unstable, it is characterized by each cluster in that stage, while every cluster in the metastable or stable growth phase is grouped via the corresponding transformed fraction, which includes every metastable or stable cluster formed for a given aging time and temperature, thus allowing phase transformation to be expressed as one equation per phase plus the nucleation equations instead of an equation per cluster of different size. This paper expands on the calculation of the problem, determining the effect of the different parameters affecting phase kinetics in the Fe-C system for very low concentrations of C.

Characterization of typical taste and odor compounds formed by Microcystis aeruginosa

Production and characteristics of typical taste and odor (T&O) compounds by Microcystis aeruginosa were investigated. A few terpenoid chemicals, including 2-MIB, β-cyclocitral, and β-ionone, and a few sulfur compounds, such as dimethyl sulfide and dimethyl trisulfide, were detected. β-Cyclocitral and β-carotene concentrations were observed to be relevant to the growth phases of Microcystis. During the stable growth phase, 41–865 fg/cell of β-cyclocitral were found in the laboratory culture. β-Cyclocitral concentrations correlated closely with β-carotene concentrations, with the correlation coefficient R2 = 0.96, as it is formed from the cleavage reaction of β-carotene. For dead cell cases, a high concentration of dimethyl trisulfide was detected at 3.48–6.37 fg/cell. Four T&O compounds, including β-cyclocitral, β-ionone, heptanal and dimethyl trisulfide, were tested and found to be able to inhibit and damage Microcystis cells to varying degrees. Among these chemicals, β-cyclocitral has the strongest ability to quickly rupture cells.

Formation process of the vortex ring generated by an impulsively started circular disc

AbstractWe present an experimental study on the axisymmetric vortex ring generated by a thin circular disc. The velocity and vorticity fields are measured by digital particle image velocimetry (DPIV). The finite-time Lyapunov exponent fields and the Lagrangian coherent structures (LCSs) of the vortex flow are computed in order to analyse the transport of the fluid during its formation and identify the boundary of the vortex ring. The volume, circulation and energy of the vortex ring are calculated. It is found that the formation of the vortex ring basically includes three phases: a rapid growth phase, a stable growth phase and a non-axisymmetric phase. In the rapid growth phase (dimensionless time $0\lt {T}_{n} \lt 0. 2$) during which Taylor’s inviscid estimation is valid, the circulation of the vortex ring grows and the translational velocity of the vortex ring decreases. In the stable growth phase ($0. 2\lt {T}_{n} \lt 4$), the growth rate of the circulation decreases gradually. In the non-axisymmetric phase (${T}_{n} \gt 4$), the ring loses axisymmetry due to instability. Compared with the vortex ring generated by the laminar flow from an orifice, the one generated by a circular disc always moves with the disc, and the entrained fluid decreases and the saturated circulation increases. The temporal impulse exerted by the moving disc on the fluid is estimated by DPIV measurements and is calculated using the direct momentum conservation method. The momentum of the control volume enclosing the LCS is found to occupy 64–68 % of the entire impulse exerted by the disc on the fluid.

Fracture in Westerly Granite under AE Feedback and Constant Strain Rate Loading: Nucleation, Quasi-static Propagation, and the Transition to Unstable Fracture Propagation

New observations of fracture nucleation are presented from three triaxial compression experiments on intact samples of Westerly granite, using Acoustic Emission (AE) monitoring. By conducting the tests under different loading conditions, the fracture process is demonstrated for quasi-static fracture (under AE Feedback load), a slowly developing unstable fracture (loaded at a `slow' constant strain rate of 2.5 × 10−6 /s) and an unstable fracture that develops near instantaneously (loaded at a `fast' constant strain rate of 5 × 10−5 /s). By recording a continuous ultrasonic waveform during the critical period of fracture, the entire AE catalogue can be captured and the exact time of fracture defined. Under constant strain loading, three stages are observed: (1) An initial nucleation or stable growth phase at a rate of ~ 1.3 mm/s, (2) a sudden increase to a constant or slowly accelerating propagation speed of ~ 18 mm/s, and (3) unstable, accelerating propagation. In the ~ 100 ms before rupture, the high level of AE activity (as seen on the continuous record) prevented the location of discrete AE events. A lower bound estimate of the average propagation velocity (using the time-to-rupture and the existing fracture length) suggests values of a few m/s. However from a low gain acoustic record, we infer that in the final few ms, the fracture propagation speed increased to 175 m/s. These results demonstrate similarities between fracture nucleation in intact rock and the nucleation of dynamic instabilities in stick slip experiments. It is suggested that the ability to constrain the size of an evolving fracture provides a crucial tool in further understanding the controls on fracture nucleation.

A crack propagation criterion based on local shear strain in adhesive bonds subjected to shear

Direct observations show that the fracture of thin adhesive bonds subjected to shear is characterized by stable crack propagation along the interface followed by catastrophic growth. Other failure processes are observed during the stable growth phase, including crack kinking, development of a large void at the crack tip and formation of a detrimental interface micro-debond ahead of the main crack. The specific choice depends on factors such as the position of the precrack plane within the adhesive layer, the layer thickness and the loading level. Regardless of the specimen geometry, the entire interfacial crack propagation event is controlled by a single parameter—a critical shear strain at the crack tip that is independent of the bond thickness and the shearing direction but is a (decreasing) function of the crack velocity. The results can be useful in the application of fracture mechanics to the design of microlaminates, composites, traditional adhesive bonding and other technologies in which thin adhesive layers are used.

Nitrate availability and shoot area development in small willow (Salix viminalis)

Abstract. The effect of nitrate supply upon leaf area development in willow (Salix viminalis) was investigated. Rooted cuttings were grown in culture solution at two different rates of exponentially‐increasing nitrate supply and with free access to other nutrients. During the lag‐phase in attaining stable nutrition, the rate of production of unfolded leaves, in the treatment with poorer N‐supply, decreased. After acclimation to the different N‐availabilities, the rate of dry matter increase per plant nitrogen was constant and the same in both treatments. The ratio of total leaf area to total amount of nitrogen in the plant was slightly higher in the treatment with poorer nitrogen supply. During the exponential (stable) phases of growth, nearly all the increase in total leaf area was attributable to main‐stem leaves; large numbers of leaves on axillary shoots in the treatment with better N‐supply contributed little to the total area. During the stable growth phase, the rate of production of unfolded leaves was the same in both treatments. Higher maximum values of relative rate of increase in area of single leaves were found with a better N‐supply and at higher leaf positions on the main stem. The duration of leaf expansion was not much affected by N‐supply. Final leaf size was greater at higher positions on the main‐stem. Within a treatment (investigated for poorer N‐supply), differences in final leaf size were proportional to differences in numbers of epidermal cells. Final leaf size was greater, at the same node, in the treatment with better N‐supply. Better N‐availability had increased the final size but not the number of epidermal cells. It was concluded that the higher exponential rate of total area increase with a better N‐supply was largely associated with higher rates of expansion in epidermal cells.

Plessite formation by discontinuous precipitation reaction from γ-Fe,Ni in Richardton (H5) ordinary chondrite

Discontinuous precipitation reactions involve the growth of stable phases behind a grain boundary migrating into a supersaturated solid-solution1, and have been synthesized in Fe,Ni alloys at temperatures ⩾500 °C (ref. 2). Axon and Grokhovsky3 have recently described localized, low temperature (350–400 °C) discontinuous precipitation reactions of the type α→[α + γ] (ref. 2) occurring naturally in initially slowly cooled α-Fe,Ni (kamacite) in the Richardton H-group ordinary chondrite. In this further study of the same meteorite we describe a complementary discontinuous precipitation reaction in zoned γ-Fe,Ni (taenite) which has produced plessite (α+ γ-Fe,Ni). Microscopic discontinuous precipitation reactions in Richardton metal occurred at lower temperatures (350 °C) and, in the case of zoned γ-taenite, at higher Ni contents than those synthesized in the laboratory2. We suggest that discontinuous precipitation may be an important mechanism for the production of plessite in strained then annealed, or shock reheated, meteorites.