scholarly journals Study on the Microscopic Characteristics of Ferruginous cement of Banguo Earth Forest in Yuan mou area, Yunnan, China

2019 ◽  
Vol 23 (3) ◽  
pp. 191-198
Author(s):  
Penghui Luo ◽  
Shitao Zhang ◽  
Yimin Tian ◽  
Fei Ding ◽  
Zongming Xu
Keyword(s):  
Spatial Structure ◽  
Clay Minerals ◽  
Yunnan Province ◽  
Soil Column ◽  
Mechanical Tests ◽  
The Self ◽  
Column Height ◽  
Curing Agent ◽  
Iron Compounds ◽  
Dispersed Particles

The column height of earth forest is generally 8~30m in yuanmou county of yunnan province, which is far higher than the self-supporting height of general soil column. Ferruginous cement is an important reason for formation of the tall and erect columnar soil. Macroscopic physical and mechanical tests confirmed that the strength of the stratum containing ferruginous cement was much higher than that of the formation without ferruginous cement. The microstructure and morphology of ferruginous cement were analyzed by SEM and EDS. It is found that ferruginous cement is mainly composed of iron compounds and clay minerals, which only exists in certain stratum. In the process of growth, Iron compounds chemically bond with clay minerals during growth to form ferruginous cements, which first form unique sphere on the surface of particles or clay minerals. It then clumps together and fills the spaces between the particles. Finally, the dispersed particles are connected together to form a stable lamellar spatial structure, which greatly improves the strength of the soil. Through the study of ferruginous cement, the mechanism of this natural curing agent is understood, which enriches the research content in this field.

scholarly journals The origin of life: the first self-replicating molecules were nucleotides

2019 ◽  
Author(s):  
Ken Ohsaka
Keyword(s):  
Origin Of Life ◽  
Clay Minerals ◽  
The Self ◽  
Rna Molecules ◽  
Simulated Environments ◽  
The Origin Of Life ◽  
Prebiotic Earth ◽  
Self Replication

Difficulties to synthesize RNA nucleotides from their subunits in modern labs under simulated environments leads us to propose a possible process for the synthesis by cross complimentary self-replication with help of clay minerals, which might be operated on prebiotic Earth. Clay minerals are known to be good catalysts and certainly existed on prebiotic Earth. The self-replication of RNA nucleotides (monomers) may be considered as the origin of potential self-replication of some extant RNA polymers, and also the reason for homochirality of RNA molecules.

scholarly journals Self-Healable Supramolecular Vanadium Pentoxide Reinforced Polydimethylsiloxane-Graft-Polyurethane Composites

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 41 ◽  
Author(s):  
Ali Berkem ◽  
Ahmet Capoglu ◽  
Turgut Nugay ◽  
Erol Sancaktar ◽  
Ilke Anac
Keyword(s):  
Tensile Strength ◽  
Vanadium Pentoxide ◽  
Coupling Reaction ◽  
Optical Microscope ◽  
Mechanical Tests ◽  
Healing Time ◽  
The Self ◽  
Supramolecular Polymer ◽  
Self Healing ◽  
Healing Efficiency

The self-healing ability can be imparted to the polymers by different mechanisms. In this study, self-healing polydimethylsiloxane-graft-polyurethane (PDMS-g-PUR)/Vanadium pentoxide (V2O5) nanofiber supramolecular polymer composites based on a reversible hydrogen bonding mechanism are prepared. V2O5 nanofibers are synthesized via colloidal route and characterized by XRD, SEM, EDX, and TEM techniques. In order to prepare PDMS-g-PUR, linear aliphatic PUR having one –COOH functional group (PUR-COOH) is synthesized and grafted onto aminopropyl functionalized PDMS by EDC/HCl coupling reaction. PUR-COOH and PDMS-g-PUR are characterized by 1H NMR, FTIR. PDMS-g-PUR/V2O5 nanofiber composites are prepared and characterized by DSC/TGA, FTIR, and tensile tests. The self-healing ability of PDMS-graft-PUR and composites are determined by mechanical tests and optical microscope. Tensile strength data obtained from mechanical tests show that healing efficiencies of PDMS-g-PUR increase with healing time and reach 85.4 ± 1.2 % after waiting 120 min at 50 °C. The addition of V2O5 nanofibers enhances the mechanical properties and healing efficiency of the PDMS-g-PUR. An increase of healing efficiency and max tensile strength from 85.4 ± 1.2% to 95.3 ± 0.4% and 113.08 ± 5.24 kPa to 1443.40 ± 8.96 kPa is observed after the addition of 10 wt % V2O5 nanofiber into the polymer.

scholarly journals Spatial Structure Characteristics of Slope Farmland Quality in Plateau Mountain Area: A Case Study of Yunnan Province, China

2020 ◽  
Vol 12 (17) ◽  
pp. 7230
Author(s):  
Zhengfa Chen ◽  
Dongmei Shi
Keyword(s):  
Spatial Distribution ◽  
Spatial Structure ◽  
Yunnan Province ◽  
Hot Spot ◽  
Mountain Region ◽  
Cold Spot ◽  
Structure Characteristics ◽  
Spot Area ◽  
Slope Farmland ◽  
Southern Fringe

As an important part of farmland, the slope farmland is widely distributed in the central and western plateau mountain region in China. It is necessary to scientifically evaluate the slope farmland quality (SFQ) and analyze the spatial structure characteristics of SFQ to ensure reasonable utilization and partition protection of slope farmland resources. This paper takes the typical plateau mountain region—Yunnan Province in China—as an example and systematically identifies the leading factors of SFQ. The sloping integrated fertility index (SIFI) is adopted to reflect the SFQ. The evaluation system is built to quantitatively evaluate the SFQ and the spatial structure characteristics of SFQ were analyzed by a geostatistical model, autocorrelation analysis and spatial cold–hot spot analysis. The results show that the SFQ indexes in Yunnan Province are between 0.36 and 0.81, with a mean of 0.59. The SFQ grade is based on sixth-class, fifth-class, seventh-class and fourth-class land. The SFQ indexes present a normal spatial distribution, and the Gaussian model fits well with the semi-variance function of the spatial distribution of SFQ indexes. Furthermore, the spatial distribution of SFQ indexes is moderately autocorrelated. The structural factors play a major role in the spatial heterogeneity of SFQ indexes, but the influence of random factors should not be ignored. The spatial distribution of SFQ grades has a significant spatial aggregation characteristic, and the types of local indicators of spatial association (LISA) are based on high–high (HH) aggregation and low–low (LL) aggregation. The cold spot and hot spot distributions of SFQ grades display the significant spatial difference. The hot spot area is mainly distributed in Central Yunnan and the Southern Fringe, while the cold spot area mainly distributes in the Northeastern Yunnan, Northwestern Yunnan and Southwestern Yunnan. This study could provide a scientific basis for SFQ management and ecological environment protection in the plateau mountain region.

Preparation and Performance of Self-Healing Epoxy Composites by Microcapsulated Approach

2014 ◽  
Vol 636 ◽  
pp. 73-77 ◽  
Author(s):  
Xin Hua Yuan ◽  
Qiu Su ◽  
Li Yin Han ◽  
Qian Zhang ◽  
Yan Qiu Chen ◽  
...  
Keyword(s):  
Impact Strength ◽  
Epoxy Matrix ◽  
The Self ◽  
Epoxy Composites ◽  
Fracture Plane ◽  
Crack Plane ◽  
Curing Agent ◽  
Self Healing ◽  
Healing Agent ◽  
The Impact

Microencapsulated E-51 epoxy resin healing agent and phthalic anhydride latent curing agent were incorporated into E-44 epoxy matrix to prepare self-healing epoxy composites. When cracks were initiated or propagated in the composites, the microcapsules would be damaged and the healing agent released. As a result, the crack plane was healed through curing reaction of the released epoxy latent curing agent. In the paper, PUF/E-51 microcapsules were prepared by in-situ polymerization. The mechanical properties of the epoxy composites filled with the self-healing system were evaluated. The impact strength and self-healing efficiency of the composites are measured using a Charpy Impact Tester. Both the virgin and healed impact strength depends strongly on the concentration of microcapsules added into the epoxy matrix. Fracture of the neat epoxy is brittle, exhibiting a mirror fracture surface. Addition of PUF/E-51 microcapsules decreases the impact strength and induces a change in the fracture plane morphology to hackle markings. In the case of 8.0 wt% microcapsules and 3.0 wt% latent hardener, the self-healing epoxy exhibited 81.5% recovery of its original fracture toughness.

scholarly journals FENOMENA TRANSPORT KOBALT-60 PADA LAPISAN TANAH

2013 ◽  
Vol 3 (1) ◽  
pp. 21
Author(s):  
Ngasifudin .
Keyword(s):  
Transport Phenomenon ◽  
Manganese Oxide ◽  
Clay Minerals ◽  
Concentration Profile ◽  
Maximum Concentration ◽  
Soil Column ◽  
Extraction Methods ◽  
Soil Component ◽  
Soil Components ◽  
Column Extraction

The transport phenomena of cobalt-60 (Co-60) in the soillayer has been investigated using column and batch methods. The association of Co-60 with soil and its components were studied by extraction methods. The concentration profile of Co-60 in the soil column was composed of two logarithmic curves that showing Co-60 would be consist of mobile and immobile fraction. The immobile fraction of Co-60 was adsorbed by soil and was distributed near in the top of column. Although the mobile Co-60 was little sorbed by soil and migrated through the soil column, themaximum concentration of Co-60 in the effluents decreased slightly with increasing length of the soil column. Extraction of Co-60 from the soil and from its components showed that Co-60 was sorbed by manganese oxide and clay minerals. Manganese oxide is one of the soil components that could be decrease the maximum concentration of Co-60 in the effluents. Although the content of manganese oxide in the soil was 0.24-0.29%, manganese oxide is the important component to preventthe migration of Co-60 in the low acidic solution.Keywords : Transport phenomenon, Cobalt-60, soil component Telah dilakukan penelitian tentang fenomena gerakan Kobalt-60 (Co-60) pada lapisan tanah yang dilakukan secara kolom dan batch. Penggabungan Co-60.dengan tanah dan komponennya dipelajari dengan serangkaian teknik ekstraksi. Gambaran konsentrasi Co- 60 di dalam kolom tanah tersusun oleh dua kurva logaritma yang menunjukkan Co-60 terdiri atas fraksi gerak dan tidak-gerak. Fraksi Co-60 tidak-gerak diserap oleh tanah dan didistribusikan di dekat bagian atas kolom. Meskipun Co-60 fraksi gerak hanya sedikit terserap oleh tanah dan di-transportkan melalui kolom tanah, konsentrasi maksimum Co- 60 di dalam efluen sedikit menurun dengan kenaikan panjang kolom tanah. Ekstraksi Co-60 dari tanah dan komponennya menunjukkan bahwa Co-60 diserap oleh mangan dioksida dan komponen lempung. Mangan oksida merupakan salah satu komponen tanah yang dapat menurunkan konsentrasi maksimum Co-60 di dalam efluen. Bahkan kandungan mangan oksida 0,24-0,29% dalam tanah menjadi komponen penting untukmencegah proses transport Co-60 pada larutan keasaman rendah.Kata kunci : Fenomena transport, Kobalt-60, komponen tanah 

Preparation of polyoxymethylene/methyl vinyl silicone rubber/thermoplastic polyurethane ternary thermoplastics vulcanizates with good toughness properties

2021 ◽  
pp. 089270572110571
Author(s):  
Wei Fang ◽  
Xiaodong Fan ◽  
Ruilong Li
Keyword(s):  
Silicone Rubber ◽  
Thermoplastic Polyurethane ◽  
Mechanical Tests ◽  
Curing Agent ◽  
Dynamic Vulcanization ◽  
Elongation At Break ◽  
Methyl Vinyl ◽  
Thermoplastic Vulcanizates ◽  
Vulcanization Process ◽  
Batch Mixer

Novel thermoplastic vulcanizates (TPVs) based on polyoxymethylene (POM) and methyl vinyl silicone rubber (MVQ) have been prepared by dynamic vulcanization process through a batch mixer. During the preparation of TPV blends, Di-(tert butyl peroxyisopropyl) benzene (BIBP) was used as the curing agent in order to make MVQ cross-linked and TPU was used to coat MVQ for improving the compatibility of MVQ and POM. In order to understand the influence of different compositions on TPV blends, five groups of experimental processes were described in detail. During these experiments, the amount of POM was reduced from 70phr to 30phr, that of MVQ was gradually increased from 18phr to 42 phr, and TPU was increased from 12phr to 28phr. In addition, the morphology and properties of TPVs were studied by DSC, FTIR, SEM, DMA and mechanical tests. The mechanical testing results showed that with the amount of POM decreasing and the total amount of MVQ and TPU increasing, the tensile strength of the TPV blends gradually was decreased, and the elongation at break was increased accordingly from 35.2 ± 6% of pure POM to 142.8 ± 11% of sample 5#.

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