scholarly journals Fluctuations in Graphitization of Coal Seam-Derived Natural Graphite upon Approaching the Qitianling Granite Intrusion, Hunan, China

Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1147
Author(s):  
Yingke Wu ◽  
Kuo Li ◽  
Zhaoguo Wang ◽  
Mianshu Hu ◽  
Haiyue Cao ◽  
...  
Keyword(s):  
Coal Seam ◽  
Spatial Relationship ◽  
Structural Features ◽  
Hunan Province ◽  
Spectroscopic Techniques ◽  
Natural Graphite ◽  
Spectral Parameters ◽  
Granite Intrusion ◽  
Mineral Catalysis ◽  
Degree Of Graphitization

The Lutang graphite deposit in Chenzhou, Hunan province, China, is a well-known coal seam-derived graphite (graphite formed from coal during its natural evolution) deposit with proven reserves of 9.5 million tons and prospective reserves of around 20 million tons (2015 data). The graphite occurs at an andalusite bearing sericite quartz chlorite metamorphic mudstone around a c. 530 km2 Qitianling granite intrusion. A set of coal seam-derived graphite samples from the Lutang graphite deposit in Hunan was examined by geochemical, crystallographic, and spectroscopic techniques to assess changes in the degree of graphitization approaching the intrusion. The carbon content, degree of graphitization, and Raman spectral parameters of series coal seam-derived natural graphite samples show a fluctuating increase with increasing proximity to the granite intrusion. The profile of geological structural features has a close spatial correlation with the variations in the degree of graphitization of series coal seam-derived natural graphite, and a strain-enhanced graphitization model is proposed. Moreover, the geographical distribution and the degree of graphitization are positively related to changes in the iron content of chlorite, suggesting a graphitization process promoted by mineral catalysis during metamorphism. A close spatial relationship exists between graphite mineral and chlorite occurrences when approaching the intrusive mass. The results of this research are important for understanding the role of tectonic stress and mineral catalysis on the genesis of coal-derived graphite.

Efficient Synthesis of Novel N-[4-Methyl-3-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)thiazol-2(3H)-ylidene]benzamide Hybrid Ring System as Potential Antibacterial Agents

2021 ◽  
Vol 17 ◽  
Author(s):  
Hummera Rafique ◽  
Aamer Saeed ◽  
Muhammad Naseem ◽  
Tauqeer Riaz ◽  
Fouzia Perveen ◽  
...  
Keyword(s):  
Bacterial Resistance ◽  
Antioxidant Activities ◽  
Antibacterial Properties ◽  
Antibacterial Activities ◽  
Structural Features ◽  
Ring System ◽  
Biologically Active ◽  
Thiazole Ring ◽  
Spectroscopic Techniques ◽  
Hybrid Ring

Background: Heterocyclic compounds display versatile biological applications, so the aim of this paper was to prepare biologically important heterocycles with enhanced bacterial resistance and to evaluate for their various structural features that are responsible for their biological properties. Objective: The objective was to synthesize bacterial resistance compounds with enhanced antibacterial properties. Method: Ester moiety containing thiazole ring was converted into its hydrazide derivatives. These heterocyclic derivatives were cyclized into another ring oxadiazole; hence a hybrid ring system of two biologically active rings was prepared. Result: All the synthesized compounds were characterized by spectroscopic techniques and were screened for their antibacterial potential; they possess significant antibacterial activities. Conclusion: New hybrid heterocyclic ring systems were synthesized by cyclization of hydrazide derivatives by adopting two step strategy in good yields. All the synthesized compounds were evaluated for their antioxidant activities; they showed moderate to significant activities. QSAR and Molecular docking studies were performed to determine the mode of interaction. Experimental and computational data is in accordance with the determined antibacterial activities.

Metamorphic fluids and transtension in the Cantabrian Mountains of northern Spain: an application of the conodont colour alteration index

1986 ◽  
Vol 123 (6) ◽  
pp. 673-681 ◽  
Author(s):  
J. G. M. Raven ◽  
Ben A. Van Der Pluijm
Keyword(s):  
Large Scale ◽  
Fluid Transport ◽  
Spatial Relationship ◽  
Structural Features ◽  
Lower Permian ◽  
Low Grade ◽  
Northern Spain ◽  
Cantabrian Zone ◽  
Conodont Colour Alteration Index ◽  
Colour Alteration

AbstractConodont colour alteration index (CAI) values from Upper Paleozoic rocks in the Cantabrian zone of northern Spain show that temperatures during Hercynian metamorphism locally exceeded 300 °C. Various temperature domains have been defined, which are generally separated by fundamental structures. These domains do not correspond with the tripartite subdivision based on stratigraphic analysis.The observed CAI values of conodonts are in general agreement with the mineral paragenesis. Areas with high CAI values display extensive alteration and mineralization, and where CAI values exceed 4–4.5 (>200 °C) slaty cleavage has developed.The Cantabrian zone is an area of very low grade metamorphism, where peak conditions were reached in Upper Carboniferous to Lower Permian times. The characteristics of the metamorphism and its spatial relationship with major faults suggest that fluids were the main source for regional heating and that fluid transport was focussed along crustal-scale structural features.The overall deformation regime in this part of the Variscan orogen of western Europe is interpreted to be large-scale transtension. This is in agreement with earlier proposed models for the formation of Upper Palaeozoic basins in this area.

scholarly journals Structural Insights into CB1 Receptor Biased Signaling

2019 ◽  
Vol 20 (8) ◽  
pp. 1837 ◽  
Author(s):  
Al-Zoubi ◽  
Morales ◽  
Reggio
Keyword(s):  
Signaling Pathways ◽  
Conformational Changes ◽  
Intracellular Signaling ◽  
Cannabinoid Receptors ◽  
Computational Modelling ◽  
Structural Features ◽  
Cb1 Receptor ◽  
Effector Proteins ◽  
Spectroscopic Techniques ◽  
Receptor Ligands

The endocannabinoid system has emerged as a promising target for the treatment of numerous diseases, including cancer, neurodegenerative disorders, and metabolic syndromes. Thus far, two cannabinoid receptors, CB1 and CB2, have been discovered, which are found predominantly in the central nervous system (CB1) or the immune system (CB2), among other organs and tissues. CB1 receptor ligands have been shown to induce a complex pattern of intracellular effects. The binding of a ligand induces distinct conformational changes in the receptor, which will eventually translate into distinct intracellular signaling pathways through coupling to specific intracellular effector proteins. These proteins can mediate receptor desensitization, trafficking, or signaling. Ligand specificity and selectivity, complex cellular components, and the concomitant expression of other proteins (which either regulate the CB1 receptor or are regulated by the CB1 receptor) will affect the therapeutic outcome of its targeting. With an increased interest in G protein-coupled receptors (GPCR) research, in-depth studies using mutations, biological assays, and spectroscopic techniques (such as NMR, EPR, MS, FRET, and X-ray crystallography), as well as computational modelling, have begun to reveal a set of concerted structural features in Class A GPCRs which relate to signaling pathways and the mechanisms of ligand-induced activation, deactivation, or activity modulation. This review will focus on the structural features of the CB1 receptor, mutations known to bias its signaling, and reported studies of CB1 receptor ligands to control its specific signaling.

scholarly journals The Fine Characterization and Potential Photocatalytic Effect of Semiconducting Metal Minerals in Danxia Landforms

Minerals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 554
Author(s):  
Yuxiong Xiao ◽  
Yanzhang Li ◽  
Hongrui Ding ◽  
Yan Li ◽  
Anhuai Lu
Keyword(s):  
Electron Microscopy ◽  
Environmental Effects ◽  
Spatial Relationship ◽  
Environmental Scanning Electron Microscopy ◽  
Optical Microscope ◽  
Element Distribution ◽  
Hunan Province ◽  
Red Beds ◽  
X Ray ◽  
Danxia Landform

The Danxia landform is representative of the Cretaceous continental red sediment. The careful identification and potential environmental effects of minerals in Danxia red beds have yet to be clearly reported. In this work, reddish sandstone samples were collected from Lang Mountain Danxia landform in Xinning, Hunan province, China, and their mineral phases, element distribution, microstructure, and the spatial relationship of different minerals were investigated using polarizing optical microscope, environmental scanning electron microscopy, energy-dispersive X-ray analysis, electron probe microanalysis, micro-Raman spectra, micro- X-ray diffraction, X-ray fluorescence spectroscopy, and high-resolution transmission electron microscopy. The results revealed that iron oxide (mainly hematite) and titanium oxide (mainly anatase) were the dominant minerals in Danxia red layers. Microcrystalline hematite was suggested as being the coloring mineral. Anatase, reported here for the first time in Danxia red beds, constituted the content of titanium in the red layer (0.17–0.57%) and was present in a significantly higher amount than the adjacent limestone formation (0.13%). Over 95% of Fe/Ti oxides served as a cementation agent along the framework of coarse-grain minerals (quartz and feldspar). The hematite and anatase were visible-light-responsive semiconductors, with a band gap of 2.01 eV and 3.05 eV, respectively. Photoelectrochemical experiments were performed on synthetic hematite, anatase, and their coupled material. The inactive hematite displayed an enhanced 23-fold photocurrent at 0.8 V (vs. Ag/AgCl) when coupled with anatase. Furthermore, in a photodegradation experiment using methyl orange dye under simulated sunlight, the coupled material showed decolorizing efficiency 2.4 times that of hematite. The anatase, therefore, prominently improved the photocatalytic activities of hematite. It is proposed that these semiconducting minerals in red beds produce oxygen reactive species and have significant environmental effects, which is of great importance.

scholarly journals New Cobalt (II) Complexes with Imidazole Derivatives: Antimicrobial Efficiency against Planktonic and Adherent Microbes and In Vitro Cytotoxicity Features

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 55
Author(s):  
Alina Fudulu ◽  
Rodica Olar ◽  
Cătălin Maxim ◽  
Gina Vasile Scăeţeanu ◽  
Coralia Bleotu ◽  
...  
Keyword(s):  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Structural Features ◽  
In Vitro Cytotoxicity ◽  
Spectroscopic Techniques ◽  
Bacterial Strains ◽  
Biofilm Growth ◽  
X Ray ◽  
Mg63 Cells

Three novel Co(II) complexes of the type [Co(C4H5O2)2L2] (where C4H5O2 is methacrylate anion; L = C3H4N2 (imidazole; HIm) (1), C4H6N2 (2-methylimidazole; 2-MeIm) (2), C5H8N2 (2-ethylimidazole; 2-EtIm) (3)) have been synthesized and characterized by elemental analysis, IR and UV-Vis spectroscopic techniques, thermal analysis and single crystal X-ray diffraction. X-ray crystallography revealed for complexes (1) and (2) distorted trigonal bipyramid stereochemistry for Co(II), meanwhile for complex (3) evidenced that the unit cell comprises three molecular units with interesting structural features. In each unit, both stereochemistry adopted by metallic ion and coordination modes of carboxylate anions are different. The screening of antimicrobial activity revealed that Candida albicans planktonic cells were the most susceptible, with minimal inhibitory concentration (MIC) values of 7.8 μg/mL for complexes (1) and (2) and 15.6 μg/mL for complex (3). Complexes (1) and (2) proved to be more active than complex (3) against the tested bacterial strains, both in planktonic and biofilm growth state, with MIC and minimal biofilm eradication concentration (MBEC) values ranging from 15.6 to 62.5 μg/mL, the best antibacterial effects being noticed against Staphylococcus aureus and Pseudomonas aeruginosa. Remarkably, the MBEC values obtained for the four tested bacterial strains were either identical or even lower than the MIC ones. The cytotoxicity assay indicated that the tested complexes affected the cellular cycle of HeLa, HCT-8, and MG63 cells, probably by inhibiting the expression of vimentin and transient receptor potential canonical 1 (TRPC1). The obtained biological results recommend these complexes as potential candidates for the development of novel anti-biofilm agents.

scholarly journals Experimental and Theoretical Investigation of Overburden Failure Law of Fully Mechanized Work Face in Steep Coal Seam

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Ze Liao ◽  
Tao Feng ◽  
Weijian Yu ◽  
Genshui Wu ◽  
Ke Li ◽  
...  
Keyword(s):  
Coal Seam ◽  
Mechanical Model ◽  
Hunan Province ◽  
Working Face ◽  
Overburden Failure ◽  
Geological Conditions ◽  
Fracture Area ◽  
Bending Fracture ◽  
Similar Simulation ◽  
Roof Deformation

In this study, both theoretical analysis and similar simulation experiment are employed to investigate the overburden failure law of fully mechanized face in the steep coal seam. By establishing the mechanical model of inclined rock beam, the deflection equation of overlying strata beam is obtained. Based on the geological conditions of Xiangyong coal mine in Hunan Province of China, the laws of roof deformation and failure in steep coal seam are obtained by similar simulation experiments. The results showed that the roof deformation of the goaf is relatively large after the working face advances along the strike, and the deformation mainly occurs in the upper roof of the goaf. The backward gangue in the immediate roof fills the lower part of the goaf, which plays a supporting role in the lower part of the roof and floor. The roof fracture of goaf is located in the middle and upper parts of the working face, which is consistent with the results derived from the mechanical model. After the roof fracture, a “trapezoid” bending fracture area and the secondary stability system area is formed, which is composed of four areas: the lower falling and filling support area, the upper strata bending fracture area, the fracture extension area, and the roof bending sinking area.

scholarly journals Track-to-Track Association Based on Structural Similarity in the Presence of Sensor Biases

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Hongyan Zhu ◽  
Suying Han
Keyword(s):  
Structural Feature ◽  
Spatial Relationship ◽  
Structural Similarity ◽  
Structural Features ◽  
Bias Estimation ◽  
Track Association ◽  
Simulation Results ◽  
The Absolute ◽  
Absolute Coordinates ◽  
Computational Intractability

The paper addresses the problem of track-to-track association in the presence of sensor biases. In some challenging scenarios, it may be infeasible to implement bias estimation and compensation in time due to the computational intractability or weak observability about sensor biases. In this paper, we introduce the structural feature for each local track, which describes the spatial relationship with its neighboring targets. Although the absolute coordinates of local tracks from the same target are severely different in the presence of sensor biases, their structural features may be similar. As a result, instead of using the absolute kinematic states only, we employee the structural similarity to define the association cost. When there are missed detections, the structural similarity between local tracks is evaluated by solving another 2D assignment subproblem. Simulation results demonstrated the power of the proposed approach.

scholarly journals Polarity-Based Sequential Extraction as a Simple Tool to Reveal the Structural Complexity of Humic Acids

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 587
Author(s):  
Vojtěch Enev ◽  
Petr Sedláček ◽  
Leona Kubíková ◽  
Šárka Sovová ◽  
Leoš Doskočil ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Extraction Procedure ◽  
Physicochemical Characterization ◽  
Structural Complexity ◽  
Structural Features ◽  
Chemical Extraction ◽  
Spectroscopic Techniques ◽  
Humic Material ◽  
Sequential Chemical Extraction ◽  
Organic Fractions

A sequential chemical extraction with a defined series of eluotropic organic solvents with an increasing polarity (trichloromethane < ethyl acetate < acetone < acetonitrile < n-propanol < methanol) was performed on peat-bog humic acid. Six organic fractions were obtained and subjected to a physicochemical characterization utilizing methods of structural and compositional analysis. Advanced spectroscopic techniques such as Attenuated Total Reflectance (ATR-FTIR), total luminescence, and liquid-state 13C NMR spectrometry were combined with elemental analysis of the organic fractions. In total, the procedure extracted about 57% (wt.) of the initial material; the individual fractions amounted from 1.1% to 19.7%. As expected, the apolar solvents preferentially released lipid-like components, while polar solvents provided organic fractions rich in oxygen-containing polar groups with structural parameters closer to the original humic material. The fraction extracted with acetonitrile shows distinct structural features with its lower aromaticity and high content of protein-like structural motifs. The last two—alcohol extracted—fractions show the higher content of carbohydrate residues and their specific (V-type) fluorescence suggests the presence of plant pigment residues. The extraction procedure is suggested for further studies as a simple but effective way to decrease the structural complexity of a humic material enabling its detail and more conclusive compositional characterization.

scholarly journals Sustainable Esterification of a Soda Lignin with Phloretic Acid

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 637
Author(s):  
Antoine Adjaoud ◽  
Reiner Dieden ◽  
Pierre Verge
Keyword(s):  
Building Blocks ◽  
Structural Features ◽  
Solubility Parameters ◽  
Molar Ratio ◽  
Spectroscopic Techniques ◽  
Hansen Solubility Parameters ◽  
Sustainable Building ◽  
Soda Lignin ◽  
Fischer Esterification ◽  
The Impact

In this work, a sustainable chemical process was developed through the Fischer esterification of Protobind® lignin, a wheat straw soda lignin, and phloretic acid, a naturally occurring phenolic acid. It aimed at increasing the reactivity of lignin by enhancing the number of unsubstituted phenolic groups via a green and solvent-free chemical pathway. The structural features of the technical and esterified lignins were characterized by complementary spectroscopic techniques, including 1H, 13C, 31P, and two-dimensional analysis. A substantial increase in p-hydroxyphenyl units was measured (+64%, corresponding to an increase of +1.3 mmol g−1). A full factorial design of the experiment was employed to quantify the impact of critical variables on the conversion yield. The subsequent statistical analysis suggested that the initial molar ratio between the two precursors was the factor predominating the yield of the reaction. Hansen solubility parameters of both the technical and esterified lignins were determined by solubility assays in multiple solvents, evidencing their high solubility in common organic solvents. The esterified lignin demonstrated a better thermal stability as the onset of thermal degradation shifted from 157 to 220 °C, concomitantly to the shift of the glass transition from 92 to 112 °C. In conclusion, the esterified lignin showed potential for being used as sustainable building blocks for composite and thermoset applications.

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