Physicochemical composition and climate response of surface sediments at different altitudes in Motuo on the southern slope of the Himalayas

Background,aim,and scope Certain physicochemical indexes of topsoil are closely related to climatic factors including temperature,and precipitation.Understanding the relationship between modern topsoil properties and climatic factors is essential for quantitative paleoclimate reconstruction.Motuo located in the eastern Himalayas,exhibits a significant elevation gradient of over 7000 m from Nnamjagbarwa Peak(7782 m a.s.l.)to the Baxika(150 m a.s.l.).This region features a complete vertical zonation of vegetation,from alpine meadow to tropical forest,presenting an ideal place to investigate the relationships among vegetation,soil and climate conditions across altitudinal gradients.This study aims to explore the vertical variations in the physicochemical composition of topsoil and its relationship with temperature and precipitation.Materials and methods Twenty-seven topsoil samples were collected at 100 m intervals from 800 m to 3600 m a.s.l.along the southern slope of the Himalayas.Grain size,magnetic susceptibility and geochemical elements were measured to discuss the vertical variation characteristics of topsoil composition and their correlation with climatic factors.Results(1)The grain size of topsoil at different altitudes in Motuo is mainly composed of sand accounting for an averaged 53.2%,followed by silt and clay.(2)In the mixed forest zone,frequency dependent magnetic susceptibility(χfd%)shows a clear relationship with altitude,and clay is positively correlated with both altitude and climatic factors.(3)The oxides of topsoil in this area mainly consist of SiO_(2),Al_(2)O_(3) and Fe_(2)O_(3),followed by MgO,CaO,Na_(2)O and K_(2)O,with slight variations in the primary components at different altitudes.The sensitivity of elements to climate varies across different altitudes and vegetation zone,likely due to the region’s complex topography and vegetation.(4)Physical and biological weathering dominates in the broad-leaved forest zone of Motuo,while chemical weathering is more prominent in the coniferous forest zone,with the mixed forest zone falling in between.Discussion The formation of topsoil across the three vegetation zones is influenced by various factors,including parent material,vegetation,and climate.In the broad-leaved forest zone,physical weathering(precipitation,root wedging etc.)and pedogenesis dominate,resulting in finer grain size.The χ_(fd)% increases with altitude likely due to the high temperature and abundant precipitation in this zone,which facilitate the transformation of strong magnetic miners into weaker ones,particularly when the soil is oversaturated.Zirconium(Zr),primarily found in zircon,is depleted at lower altitudes by strong current erosion.Barium(Ba)is similarly reduced at low altitudes in this zone.In mixed forest zone,clay content is the lowest,indicating weaker physical weathering conditions than broad-leaved forest zone.The coarser grain size may result from the combined effects of topography and vegetation coverage.Magnetic susceptibility and organic matter show a positive correlation with altitude.Zr concentration is higher than that in the broad-leaved forest zone,likely resulting from decreased precipitation.In the coniferous zone,the clay content shows considerable fluctuations,with grain size generally becoming finer as altitude increases.This trend may be explained by intensified soil disintegration from seasonal freeze-thaw cycles.The χ_(fd)% values lack a clear trend or pattern,possibly due to soil erosion causing the migration of magnetic minerals or insufficient iron precipitation,which reduces the concentration of magnetic minerals in the soil.Additionally,a positive correlation is observed between altitude and organic matter content,with higher altitudes associated with greater organic matter accumulation.This may be attributed to lower microbial activity in colder conditions,which slows the decomposition and transformation of organic matter.Conclusions The variations in grain size,magnetic susceptibility,and geochemical elements differ across altitudes and vegetation zones,closely connected to the complex interplay of terrain,vegetation,and climate in Motuo.In the mixed forest,altitude has a significant impact onχfd%,and the clay component is particularly sensitive to changes in altitude,mean annual temperature,and precipitation.Zr shows a strong correlation with altitude and climate factors,making it a valuable indicator for assessing changes in atmospheric precipitation within specific altitude ranges.Recommendations and perspectives This study enhances our understanding of the relationships between the physicochemical properties of topsoil and climate conditions,offering valuable insights for paleoclimate reconstruction in Motuo.

Improvement of oxidation resistance in graphite for MgO-C refractory through surface modification

Graphite, used as a carbon source in a conventional magnesia-carbon(MgO-C) refractory, was modified with an acid reagent, resulting in a negative charge on the surface of graphite, to enhance the coating efficiency of aluminum(Al) phase, which was compared to the pristine graphite through its dispersibity and oxidation behavior. The graphite particles with and without surface modification were added, respecticely, in an Al(NO3)3 suspension used as a coating reagent, and then filtered at room temperature. The modified graphite shows better disperbility than the pristine graphite, indicating that the coating efficiency of Al precursor is enhanced in the modified graphite. With respect to oxidation behavior, the modified graphite without the coating layer is totally reacted with oxygen at heat treatment of 900 °C in air. However, the Al-coated graphite starts to react with oxygen at heat treatment of 900 °C and fully reacted with oxygen at heat treatment of 1000 °C, showing the gray and white colors, respectively. It is verified that the Al layer is individually and uniformly formed on the surface of graphite and the oxidation resistance of graphite is enhanced owing to the increased coating efficiency of Al precursor.

Modified graphene‐based materials as effective catalysts for transesterification of rapeseed oil to biodiesel fuel

Production of biodiesel by the transesterification process using different modified graphene‐based materials as catalysts was studied.Solid acid graphene‐based samples were prepared by grafting sulfonic or phosphate groups on the surface of thermally reduced graphene oxide.The obtained materials were thoroughly characterized using scanning electron microscopy,X‐ray diffraction,thermogravimetric analysis,X‐ray photoelectron spectroscopy,N2 adsorption‐desorption measurements,potentiometric titration,elemental analysis,and Fourier transform infrared spectroscopy.The prepared catalysts were tested in the transesterification of rapeseed oil with methanol at 130°C under pressure,and their activities were compared to the performance of a commercially available heterogeneous acidic catalyst,Amberlyst‐15.All modified samples were active in the transesterification process;however,significant differences were observed in the yield of biodiesel,depending on the method of catalyst preparation and strength of the acidic sites.The highest yield of fatty acid methyl esters of 70%was obtained for thermally reduced graphene oxide functionalized with 4‐benzenediazonium sulfonate after 6 h of processing,and this result was much higher than that obtained for the commercial catalyst Amberlyst‐15.The results of the reusability test were also promising.

Molecular Dynamics Simulation on Stability of Insulin on Graphene

The adsorption dynamics of a model protein （the human insulin） onto graphene surfaces with different sizes was investigated by molecular dynamics simulations. During the adsorption, it has different effect on the stability of the model protein in the fixed and non-fixed graphene systems. The tertiary structure of the protein was destroyed or partially destroyed, and graphene surfaces shows the selective protection for some α-helices in non-fixed Systems but not in fixed systems by reason of the flexibility of graphene. As indicated by the interaction energy curve and trajectory animation, the conformation and orientation selection of the protein were induced by the properties and the texture of graphene surfaces. The knowledge of protein adsorption on graphene surfaces would be helpful to better understand stability of protein on graphene surfaces and facilitate potential applications of graphene in biotechnology.

Preparation and Characterization of TiO_2/Expanded Graphite

In order to obtain anatase TiO2/expanded graphite with high expansion volume, titania gel was introduced to expandable graphite surface by sol-gel process, and then the composite was expanded and calcined at high tempera- ture. The samples were analysed by using scanning electron microscope （SEM）, X-ray diffraction（XRD）, energy disperse spectroscopy （EDS）, and differential scanning calorimetry （DSC）. The optimal conditions for preparation are as follows： the molar ratio of tetrabutyl orthotitanate to triethanolamine is 1 ： 0.4, and the calcination and expansion temperature is in the range of 650--750 ~C. Under such conditions, the expansion volume of composites could reach 98 mE/g, and the mass loss ratio is less than 5%. The analysis shows that lower temperature and smaller particle size of graphite are helpful to the formation of anatase-type of TiO2, but larger particle size will lead to lower mass loss ratio, and higher temperature and larger particle size will lead to higher expansion volume.

Role of the HLA-DQ locus in the development of chronic gastritis and gastric carcinoma in Mexican patients

AIM： To determine the HLA-DQ locus in Mexican patients with Chronic gastritis and gastric adenocarcinoma.METHODS： Oligotyping for HLA-DQ locus was performed in 45 Mexican patients with chronic gastritis and 13 Mexican patients with diffuse-type gastric adenocarcinoma, and was then compared with 99 clinically healthy unrelated individuals. H pylori infection and CagA status were assessed in patients by enzyme-linked immunosorbent assay （EUSA） method. RESULTS： We found a significant increased frequency of HLA-DQBI＊0401 allele in Hpylori-positive patients with chronic gastritis when compared with healthy subjects [19 vs 0%, P = 1 × 10^-7, odds ratio （OR） = 4.96; 95% confidence interval （95% CI）, 3.87-6.35]. We also found a significant increased frequency of HLA-DQBI＊0501 in patients with diffuse-type gastric carcinoma in comparison with healthy individuals （P = 1 × 10^4, OR = 13.07; 95% CI, 2.82-85.14）.CONCLUSION： HLA-DQ locus may play a different role in the development of H pylori-related chronic gastritis and difffuse-type gastric adenocarcinoma in the Mexican Mestizo population.

Gas-Phase Deposited Plasmonic Nanoparticles Supported on 3D-Graphene/Nickel Foam for Highly SERS Detection

In this work, we proposed a novel three-dimensional (3D) plasmonic nanostructure based on porous graphene/nickel foam (GNF) and gas-phase deposited Ag nanoparticles (NPs). Ag NPs with high density were directly deposited on the surface of 3D GNF by performing a novel cluster beam deposition approach. In comparison with traditional Ag substrate (SiO2/Ag), such hot-spots enriched 3D nanostructure showed extremely high electromag-netic field enhancement under incident light irradiation which could be used as a sensitive chemical sensor based on surface enhanced Raman scattering (SERS). The experimental results demonstrated that the proposed nanostructure showed superior SERS performance in terms of Raman signal reproducibility and sensitivity for the probe molecules. 3D full-wave simulation showed that the enhanced SERS performance in this 3D hierarchical plasmonic nanostructure was mainly obtained from the hot-spots between Ag NPs and the near-field coupling between Ag NPs and GNF sca olds. This work can provide a novel assembled SERS substrate as a SERS-based chemical sensor in practical applications.

Electrochemical preparation and characterization of gold-polyaniline core-shell nanocomposites on highly oriented pyrolytic graphite

A simple electrochemical method for the in situ preparation of homogeneously dispersed gold-polyaniline core/shell nanocomposite particles with controlled size on the highly oriented pyrolytic graphite(HOPG)was demonstrated.The HOPG surface was modified preferentially by covalent bonding of a two-dimensional 4-aminophenyl monolayer employing diazonium chemistry.AuCl4 -ions were attached to the Ar-NH2 termination and reduced electrochemically.This results in the formation of Au nuclei that could be further grown into gold nanoparticles.The formation of polyaniline as the shell wrap of Au nanoparticle was established by localized electro-polymerization.These core-shell nanocomposites prepared were characterized by AFM and cyclic voltammetry.The results show that the gold-polyaniline core-shell composites on HOPG have a mean particle size of 100 nm in diameter and the polyaniline shell thickness is about 15 nm.

Dispersion of graphene in silane coupling agent aqueous solutions

In order to reduce the agglomeration of nanographene and improve its dispersibility,six silane coupling agents were used to modify the surface of the nanographene particles.Visual inspection,Fourier-transform infrared spectroscopy,transmission electron microscopy,Raman spectroscopy,and X-ray diffraction were employed to evaluate the dispersion properties of the resulting graphene in an aqueous solution of silane coupling agents.Results show that all six types of silane coupling agents are efficient in promoting the dispersion of graphene in aqueous solutions,and no obvious sedimentation of the graphene dispersion solution is observed after a stationary storage period of 30 d.Taking 3-aminopropyltriethoxysilane(KH-550)as an example,after the graphene is dispersed in the KH-550 aqueous solution,the carboxyl group on the surface of the graphene reacts with the KH-550 amino group to form an amide bond,and KH-550 is successfully grafted onto the graphene surface.Polar functional groups ionize in water,creating an electrostatic repulsion effect,or hydrophilic functional groups form hydrogen bonds with water molecules,which is believed to improve the dispersion stability of graphene.The dispersed graphene is curled and contains many folds.Each fold has about three or four layers,with an interlayer spacing of about 0.65 nm.The dispersed graphene also has a complete lattice and a reduced number of defects.Nanographene disperses well in silane coupling agent aqueous solutions and can,therefore,be used to prepare cement-based composites.

The expression of core fucosylated E-cadherin in cancer cells and lung cancer patients: prognostic implications

It is well documented that the glycosylation of E-cadherin is correlated with cancer metastasis, but whether E- cadherin could be core fucosylated remains largely unknown. We found that E-cadherin was core fucosylated in highly metastatic lung cancer cells while absent in lowly metastatic lung cancer cells. Since α-1,6 Fucosyltransferase (α-1,6 FucT) is known to catalyze the reaction of core fucosylation, we investigated the biological function of core fucosylation on E-cadherin by α-1,6 FucT targeted RNAi and transfecting α-1,6 FucT expression vector. As a result, calcium dependent cell-cell adhesion mediated by E-cadherin was strengthened with the reduction of core fucosylation on E- cadherin after RNAi and was weakened with the elevated core fucosylation on E-cadherin after α-1,6 FucT over expression. Our data indicated that α-1,6 FucT could regulate E-cadherin mediated cell adhesion and thus play an important role in cancer development and progression. Computer modeling showed that core fucosylation on E-cadherin could significantly impair three-dimensional conformation of N-glycan on E-cadherin and produce conformational asym- metry so as to suppress the function of E-cadherin. Furthermore, the relationship between the expression of core fucosylated E-cadherin and clinicopathological background of lung cancer patients was explored in lung cancer tissue of patients. It turns out to demonstrate that core fucosylated E-cadherin could serve as a promising prognostic indicator for lung cancer patients.

Surface Modification of Pyrolytic Carbon Black from Waste Tires and Its Use as Pigment for Offset Printing Ink

Pyrolysis has the potential of transforming waste into valuable products. Pyrolytic carbon black (PCB) is one of the most important products resulting from the pyrolysis of used tires. One of the most significant applica-tions of modified pyrolytic carbon black is its use as pigment for offset printing ink to obtain high added values. Inverse gas chromatography (IGC) results show that a large quantity of inorganic matters and carbonaceous deposit are removed by treating the pyrolytic carbon black with nitric acid solution. Plenty of active sites originally occu-pied by inorganic ash and coke are recovered. The surface energy of pyrolytic carbon black (TWPC)modified by titanate-coupling agent-especially the specific interaction γ sspdetermined by the specific probe molecule, tolu-ene-shows the strong interaction between the TWPC and the synthetic resins. The offset printing ink performance confirms the IGC prediction. And TWPC has the great potential of applications in printing ink industry as pigment.

Protection and Functionalizing of Stainless Steel Surface by Graphene Oxide-Polypyrrole Composite Coating

The corrosion inhibition of metallic substrates is a prime issue for many potential applications where corrosion plays a crucial role. The development of carbon based on functionalized coatings could increase the lifetime of metallic substrates by inhibiting the corrosion process. Present work is an effort to develop a corrosion inhibiting composite coating of graphene oxide and polypyrrole for AISI （American Iron and Steel Institute） type 304 stainless steel substrates. The electrochemical galvanostatic deposition process was applied for coating development. The coating morphology and ability to cover the substrate surface was analyzed with a high-resolution scanning electron microscope. The coating＇s structural and electronic properties were analyzed with Raman spectroscopy. The investigation of corrosion inhibition involved open circuit potential, Tafel, and voltammetry analysis. The standard salt test ASTM （American Society for Testing and Materials） G48A for stainless steel substrate has also been studied. Significant enhancement of corrosion potential as well as pitting potential for the composite coated substrates has been noted. Furthermore, corrosion and breakdown potential increased upon changing the material from graphene oxide to its composite coating. During the salt test analysis, the durability of the composite coating was noted up to 72 h, which is the standard time scale. Based on experimental analysis, this composite material can be used as an effective carbon based on functionalized corrosion inhibitor for stainless steel substrates to increase their lifetime.

Raman spectroscopy investigation of structural and textural change in C/C composites during braking

The microstructure and texture of C/C composites with a resin-derived carbon, a rough laminar （RL） pyrocarbon and a smooth laminar pyrocarbon, before and after braking tests, were investigated by Raman spectroscopy. The full width at half maximum （FWHM） of the D-band indicates the amount of defects in the in-plane lattice, while the G-to-D band intensity （peak area） ratios （lC/ID） is used to evaluate the degree of graphitization. The results show that the FWHM of D-band of sample with RL pyrocarbon changes greatly from 36 cm-1 to 168 cm 1 after braking tests, which indicates that a large number of lattice defects are produced on its wear surface. However, the graphitization degree of resin-derived carbon sample rises significantly, because the IC/1D increases from 0.427 to 0.928. Braking tests under normal loading conditions, involving high temperature and high pressure, produce a lot of lattice defects on the wear surface, and induce the graphitization of the surface. Sample with RL pyrocarbon having a low hardness is easy to deform, and has the most lattice defects on the wear surface after braking. While raw materials with resin-derived carbon have the lowest graphitization degree which rises greatly during braking.

Comparisons between Flotation Deinking Abilities of Newsprint Paper by Using Enzyme and Chemicals

The aim of this research is to study the floatation deinking abilities of black mold enzyme and chemicals in newsprint paper application. In this experiment, the properties of deinked pulp from three different additives--chemicals, black mold enzyme, and chemicals together with black mold enzyme, are studied. The first part of the experiment was to find the optimal amount of chemicals and the optimal pH through the use of sodium hydroxide and surfactant. As a result, 0.2% of sodium hydroxide and 0.4% of surfactant on oven dried weight at pH 9 was found to be the optimal condition for the deinked pulp to yield the lowest ERIC （effective residual concentration） and the highest brightness. The second part of the experiment was to find the optimal amount of black mold enzyme used in the deinking process. As a result, the optimal condition for deinked pulp to retain the lowest ERIC and the highest brightness was 100 ppm of black mold enzyme and 10 minutes of enzyme reaction time. The third part of experiment was to study the de-inking ability of black mold enzyme and chemicals. Consequently, with 30 min of chemicals reaction time and 60 min of black mold reaction time, the deinked pulp retained low ERIC but higher brightness.

Characterization of foreign grain on 6H-SiC facet

6H-SiC single crystals were grown by sublimation method. It is found that foreign grains occur frequently on the facets of the crystals. To characterize the foreign grain, a longitudinal and a sectional cut samples were prepared by standard mechanical processing method. Raman spectrum confirms that the foreign grain is actually a mis-oriented 6H-SiC grain. The surface structure of the foreign grain was studied by chemical etching and optical microscopy. It is shown that etch pits in foreign grain region take the shape of isosceles triangle, which are different from those in mono-crystalline region, and high density stacking faults are observed on the surface of the foreign grain. The orientation of foreign grain surface is determined to be （10]-4） plane by back-scattering X-ray Laue image. The X-ray powder diffraction reveals that the powder is partly graphitized after a long crystal growth rim. Therefore it is believed that the loss of Si results in the formation of C inclusions, which is responsible for the nucleation of foreign grain in the facet region.

Values and Educative Aspirations

Empirical research was done interviewing face to face a sample of 2,447, 10-12 grade students in Culiacan, Sinaloa, Mexico, from the main public university high school in town. Education is seen as a tool to develop better citizens first, and better workers later. The objective of this research was to detect different perceptions related to values and education. Using a 13 items questionnaire, we measured： Students＇ perceptions about him/herself as part of their education role, responsibility that students show toward activities m school, perceptions about education as a tool to grow in the social ladder and as a way of social recognition, social perception about effort as an important value to self-improve and get social recognition, and to finish, perceptions about their teacher＇s performance.

Taxonomy of Thermonotus Gahan(Coleoptera: Cerambycidae: Lamiinae)

Thermonotus nigripes Gahan is recorded from Yunnan, China for the first time. Photographs of habitus, hind wing and genitalia of male, a catalogue and a key to the species of the genus are presented.

Qualitative Perspective of Audit Materiality： Empirical Evidence in Mexico and Colombia

Our contribution analyzes the process of convergence with the International Standards of Audit （ISAs）, particularly those that regulate the concept of materiality in Mexico and Colombia. Between other results, across a survey, it is demonstrated why the effective use of the factors that emerge of his qualitative slope can favor the quality of the financial information that publish the audited companies, the usefulness and the comprehensibility of the report of opinion. In general, the reliability, transparency, and relevancy of the financial statements will meet potentially favored with the strict application of these major and better normative instruments.

Reading, Habitus, and Social Representations in a University Context

The lack of reading habits among Mexican population is an idea based on national and international indicators, which illustrate the danger of this situation; however, these indicators fail to go deeper into the problem. This project was aimed to obtain more information about the habitus and social representations of college students reading habits, using as theoretical elements the principles developed by Pierre Bourdieu and Serge Moscovici. The project was developed in a public university, located in Mexico＇s northeast region; 19 students were part of the sample group. Two research tools were used to obtain data： survey and focus group. The project analyzed academic and environmental aspects, beyond the ＂ought to be＂, that affected the development and provided characteristics on the daily sociocultural reality of the students, with a view of the real environment of the students without ＂make-up＂. The project deepened into the analysis of the reading practices and not only the usual numeric indicators, which traditionally condemn the reading practices in Mexico. The results of this study showed that students read a lot more than what they and their teachers think they do, this taking into consideration electronic documents, general interest publications, and commercial magazines, among others. The point of view of some teachers and researchers, when it comes to reading habits recognize non-academic, simple and interesting reading more important impact on their reading habits shows a tendency to be pedantic and canonic; it does not for young people, which in the long term, could have a

Tuning microstructure and surface chemistry of reduced graphene oxide by mild reduction

Reduced graphene oxide(RGO) sheets with varied contents and types of oxygenated groups were synthesized by Hummers treatment of natural graphite powders followed by different nontoxic and mild reduction methods, which include thermal and chemical reduction with ethylene glycol, KOH and Fe powder. The changes in microstructure and surface chemistry of RGOs were extensively characterized by SEM, TEM, AFM, XRD, XPS and Raman spectrum. The results show that significant exfoliation occurs during oxidation and is retained in reduction processes, along with the formation of curled wavy morphology. Compared with large d spacing(0.852 nm) of graphene oxide(GO), the(002) plane distance decreases to 0.358-0.384 nm of RGOs, indicating efficient tuning of surface functionalities through mild reduction methods. The ID/IG ratio of RGOs is about 1.0-1.15, indicating that reconstructed sp^2 domains have smaller sizes and larger quantity. The content of sp^2 bonded C in GO(36.93%, molar fraction) increases to 45.48%-72.92%(molar fraction) in RGOs, along with a drastic decrease in hydroxyl and epoxy and minor changes in carbonyl and carboxyl. Thermal reduction or chemical reduction produces RGOs with residual functionalities, which may render different chemical activity and is desirable in various applications.