Green Mixture Research Articles

Voltaic effect in burning high-caloric (Zr+CuO+LiF)/(Zr+BaCrO4+LiF) sandwich structures

This experimental study is devoted to the electric and optical phenomena, that becomes apparent during the combustion of the two-layer heterogeneous energetically-condensed solid-phase systems with the (Zr+CuO+LiF)/(Zr+BaCrO4+LiF) structure. It was found that such systems combustion is accompanied by an electric pulse signal generation with duration ∼ 1.0 s at half-width and the maximal amplitude 1.2-1.5 V. The signal arises at the combustion beginning and is continuing to the reaction completion. For the mentioned systems it was firstly registered a flame optical emission from the reaction zone within the visible spectral region (λ ∼ 300-700 nm). The initial (green) mixtures and combustion products were explored by x-ray diffraction and scanning electron microscopy. The combustion experiments were carried out by using a home-made experimental mounting, allowing in on-line regime to record the physical parameters of the energetically-condensed systems during a combustion process.

Abstract PR06: Effect of polyphenon E on progression to prostate cancer after diagnosis of high grade prostatic intraepithelial neoplasia

Abstract Importance: In recent years, several studies have suggested effectiveness of green tea catechins in prostate cancer (PCa) chemoprevention. With the exception of one trial from Italy, this has not been further tested in a randomized trial setting in high-risk men with atypical small acinar proliferation (ASAP) or high grade prostatic intraepithelial neoplasia (HGPIN). Objective: To determine whether the daily consumption of a standardized formulation of green tea catechins (Polyphenon E) supplement for 1 year reduces the rate of progression to PCa in men, diagnosed with HGPIN or ASAP. Additional objectives were to evaluate tolerance, lower urinary tract symptoms (LUTS) and quality of life (QOL). Design, setting and participants: A randomized, double-blinded trial was conducted from September 2008 to March 2014 at medical centers in the US targeting 97 men diagnosed HGPIN or ASAP, randomized to treatment (n=49) or control arm (n=48). Supplement or placebo was initiated within 3 months of initial biopsy and continued for 1 year. Intervention: Participants were block randomized by baseline diagnosis and study site to receive Polyphenon E (PolyE), a decaffeinated, standardized green tea catechin mixture, the main component of which is (−)-epigallocatechin-3-gallate (EGCG) at a dose of 400 mgs EGCG per day (200 mgs twice a day [BID]), or placebo. Main outcomes and measures: Rate of progression to PCa at one year in men treated with PolyE or placebo following diagnosis of HGPIN or ASAP; evaluation of tolerance, LUTS and QOL. Results: Overall, we did not observe a difference in the number of men who progressed to PCa in one year in the Poly E (4/49) arm compared to placebo arm(6/48). Secondary analyses of patients reaching a definitive endpoint revealed that among men with baseline diagnosis of HGPIN, a greater number progressed to ASAP or PCa in the placebo arm (10/25) compared to the PolyE arm (3/26; P<0.05). Interestingly, this result was largely driven by the fact that a significantly greater number of subjects with baseline HGPIN progressed to ASAP in the placebo arm (5/25) compared to men in the PolyE arm (0/26; P <0.05). In men with baseline diagnosis of ASAP, the rate of cancer diagnosis at the end of intervention were similar in both study arms. Men in the PolyE group treated for one year demonstrated a significant decrease in serum tPSA compared to those in the placebo group (-0.90 ng/mL;(95%CI:-1.67, -0.12; P<0.05). No significant differences in tolerance, LUTS or QOL were observed between the two groups. Conclusions and Relevance: Daily intake of a standardized, decaffeinated catechin mixture containing 400 mgs EGCG (200 mgs BID) for 1 year is well tolerated and appears to produce chemoprevention effects in the early stages (HGPIN to ASAP) of prostate carcinogenesis. These findings should be confirmed in a phase III clinical trial prior to recommending use in clinical settings. Trial Registration: Clinical Trials.gov Identifier: NCT00596011 Acknowledgement: The research study was funded by the National Institute of Health- National Cancer Institute R01 CA12060-01A1. We acknowledge the contributions of Anthony M. Neuger, Domenico Coppola, Binglin Yue, (Moffitt Cancer Center); Kyle Anderson (Minneapolis VA Medical Center, Minneapolis, MN); Eduard Trabulsi (Jefferson Medical College, Philadelphia, PA); Tajammul Fazili (Overton Brooks VA, Shreveport, LA); Edward Giovanucci (Harvard University); Gregory Zagaja (University of Chicago, Chicago, IL); Shahnjayla Connors (University of Washington, St. Louis, MO); Folake Odedina (University of Florida). External Data Monitoring Board: Omer Kucuk, (Emory University), Phyllis Bowen (Retired), and Steven Clinton (Ohio State University). Citation Format: Nagi B. Kumar, Julio Pow-Sang, Kathleen M. Egan, Philippe A. Spiess, Shohreh Dickinson, Raoul Salup, Mohamed Helal, Jerry McLarty, Christopher R. Williams, Fred Schreiber, Said Sebti, Aslam Kazi, Loveleen Kang, Gwen Quinn, Tiffany Smith, Karen Diaz, Ganna Chornokur, Theresa Crocker, Michael J. Schell. Effect of polyphenon E on progression to prostate cancer after diagnosis of high grade prostatic intraepithelial neoplasia. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr PR06.

Abstract B67: Effect of polyphenon E on progression to prostate cancer after diagnosis of high-grade prostatic intraepithelial neoplasia or atypical small acinar proliferation in African American men

Abstract Importance: Studies suggest that green tea catechins are worthy of investigation for prostate cancer (PCa) chemoprevention. AAM diagnosed with HGPIN had significantly elevated PCa risk, compared to AAM without HGPIN (83.3% vs 6.9%, p=0.0001). However, to date, there are no chemoprevention trials with GTC targeting a substantial number of AAM diagnosed with HGPIN, who have an exceptional risk for progression to aggressive prostate cancer. Objective: To determine whether the daily consumption of a standardized formulation of green tea catechins (Polyphenon E) supplement for 1 year reduces the rate of progression to PCa in men diagnosed with HGPIN or ASAP with a specific focus on AAM. Additional objectives were to evaluate tolerance, lower urinary tract symptoms (LUTS) and quality of life (QOL). Design, setting and participants: A randomized, double-blinded trial was conducted from September 2008 to March 2014 at 3 medical centers in the US targeting 97 men (including 20 AAM) diagnosed HGPIN or ASAP, randomized to treatment (n=49) or placebo arm (n=48). Supplement or placebo was initiated within 6 months of initial biopsy and continued for 1 year. Intervention: Participants were block randomized by baseline diagnosis to receive Polyphenon E (PolyE), a decaffeinated, standardized green tea catechin mixture, the main component of which is (−)-epigallocatechin-3-gallate (EGCG) at a dose of 400 mgs EGCG per day (200 mgs twice a day [BID]), or placebo. Main outcomes and measures: Rate of progression to PCa at one year in men treated with PolyE or placebo following diagnosis of HGPIN or ASAP; evaluation of tolerance, LUTS and QOL. Results: Overall, we did not observe a difference in the number of men who progressed to PCa in one year in the Poly E (4/49) arm compared to placebo arm(6/48). Among men with baseline diagnosis of HGPIN, a significantly greater number of subjects progressed to ASAP in the placebo arm (5/25) compared to men in the GTC arm (0/26; P <0.05). Specifically evaluating the effect of GTC in 20 AAM in this trial, results reveal that 2/12 (17%) AAM progressed to PCa in the placebo arm compared to 0/8 (0%) AAM receiving GTC. In subjects with baseline diagnosis of HGPIN, 3/9 men progressed to ASAP or PCa compared to 0/6 the GTC arm with no safety concerns. Post treatment serum tPSA was reduced in AAM on GTC (2.8ng/ml) compared to placebo (5.6ng.ml). No significant differences in tolerance, LUTS or QOL were observed between the two groups. Conclusions and Relevance: Daily intake of a standardized, decaffeinated catechin mixture containing 400 mgs EGCG (200 mgs BID) for 1 year is well tolerated and appears to produce chemoprevention effects in the early stages (HGPIN to ASAP). Targeting earlier stages of disease using chemoprevention agents with a favorable safety profile to prevent progression to clinically evident aggressive PCa may be key to eliminating disparity in PCa morbidity and mortality in the exceptionally high risk population of AAM. These findings should be confirmed in a phase III clinical trial prior to recommending use in clinical settings. Trial Registration: Clinical Trials.gov Identifier: NCT00596011 Citation Format: Nagi KUMAR, Michael Schell, Ganna Chornokur, Cathy Phelan. Effect of polyphenon E on progression to prostate cancer after diagnosis of high-grade prostatic intraepithelial neoplasia or atypical small acinar proliferation in African American men. [abstract]. In: Proceedings of the Seventh AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 9-12, 2014; San Antonio, TX. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2015;24(10 Suppl):Abstract nr B67.

Tensile and Hardness Property Evaluation of Kaolin- Sisal Fibre- Epoxy Composite

In this work, the tensile and hardness properties of Kaolin- sisal fibre- epoxy composite were evaluated using standard methods. Epoxy type 3354A with its hardener was mixed in the ratio 2:1. Calcined kaolin particle with average size of 35µm and 3-4mm sisal fibre were added to the epoxy matrix during the composite manufacture in a proportion of: 60/40 wt %, 60/30/10 wt %, 60/20/20 wt %, 60/10/30 wt % for matrix, fibre and Kaolin respectively. The green mixtures were poured into aluminum mould and left for 24 hrs to cure. The results showed that the addition of kaolin and sisal fibre affected mechanical properties of the epoxy resin. The maximum strain observed for each specimen after tensile tests were as follows: 12% for specimen A; 12% for specimen B; 3.9% for specimen C; 11.5% for specimen D and 6% for specimen E. The Shore D hardness values were as follows: 79.1 for specimen A (control); 55.68 for specimen B; 42.82 for specimen C; 78.7 for specimen D and 81.34 for specimen E. The hardness values was reduced from 55.68 to 42.83 and increased to 81.34. Specifically, the tensile and hardness properties increased proportionately with the fibre quantity and inversely proportional to the kaolin content. These are attributed to the level of bonding strengths between the fibre-matrix-particulate interfacial adhesions. http://dx.doi.org/10.4314/njt.v34i4.12

Green DES mixture as a surface treatment recipe for improving the thermoelectric properties of PEDOT:PSS films

Green DES (ChCl/urea fluid) as a novel surface treatment reagent has been proposed for improving the thermoelectric (TE) performance of PEDOT:PSS films and demonstrated satisfying effects as expected. Simultaneous increases were found in the electrical conductivity and Seebeck coefficient, which achieved further improvement by raising the treating temperature. This additional enhancement was probably attributed to that higher temperature led to decreased viscosity thus a better interaction between the DES mixture and the film surface. The maximum electrical conductivity and Seebeck coefficient were found at 120°C, reaching 85.6Scm−1 and 30.1μVK−1. Further TE improvement was obtained when DMSO was introduced to make a mixture with DES at different ratios to act as the treatment reagent, giving rise to an optimized power factor of 25.26μWm−1K−2 with the corresponding electrical conductivity and Seebeck coefficient being 424.2Scm−1 and 24.4μVK−1, respectively.

Characterization of binary and ternary mixtures of green, white and black tea extracts by electrospray ionization mass spectrometry and modeling of their in vitro antibacterial activity

In this study we modeled the in vitro antibacterial activity of the extracts of green, white and black tea mixtures using the response surface methodology. Camellia sinensis var sinensis tea mixtures were prepared according to a 3-component simplex-centroid design containing ten formulations. The antibacterial activity was used to assess the inhibition ability of the tea mixtures against a range of seven Gram positive, Gram negative, vegetative cells and sporeforming bacteria. A formulation of tea mixtures was then optimized by the desirability function aiming to maximize the inhibition of different strains and/or serotypes of Salmonella. The best tea formulation was chemically characterized by electrospray ionization mass spectrometry (ESI–MS). The linear effects of white and black teas were statistically significant (p < 0.05) as well as the interaction between green and white and green and black on the inhibition of S. Thyphimurium. Although the optimized tea mixture was effective against all Salmonella strains, the inhibition was substantially greater for specific serotypes, with differences observed even among strains of the same serotype (p < 0.05). A total of 11 phenolic constituents such as gallic acid, quinic acid, (+)-catechin/(−)-epicatechin, (−)-gallocatechin/(−)-epigalocatechin, coumaroylquinic acid, galloylquinic acid, and caffeoylquinic acid were tentatively identified using ESI–MS.

A counterview of 'An investigation of the false discovery rate and the misinterpretation of p-values' by Colquhoun (2014).

A counterview of 'An investigation of the false discovery rate and the misinterpretation of p-values' by Colquhoun (2014).

Silicon carbide ceramics SHS-produced from mechanoactivated Si–C–B mixtures

We investigated the influence of mechanical activation (MA) and initial temperature T0 on combustion temperature Tc and burning velocity Uc for 90% (Si + C)–10% (4B + C) mixtures as well as on product morphology. Mechanical activation was found to strongly change the size and morphology of Si and graphite particles (by a factor of 6–8), lead to accumulation of micro strains, and increase the reactivity of green mixture. An increase in T0 was found to proportionally increase the values of Tc and Uc but produce little or no influence on the phase composition of product. The SiC powder consisting of 50–100 nm crystallites was obtained by diminution of combustion product and then used to prepare, by hot pressing, a ceramic PVD target for magnetron sputtering.

Protective Mo2NiB2–Ni coatings by centrifugal metallothermic SHS

Cast Mo2NiB2–Ni metal-matrix composites and protective coatings thereof were fabricated by centrifugal metallothermic SHS process. The quality of SHS surfacing was found to depend on process parameters such as the mass of green mixture per unit surface area of substrate and centrifugal acceleration. The hardness of synthesized coatings was rather high and attained as large values as 800–1200 H V. Optimal conditions for deposition of high-quality protective coatings onto a steel substrate were found experimentally. The process can be recommended for practical implementation in production of cutting tools, tribological materials, molds, and deposition of protective coatings. The present results can be expected to make a theoretical background for industrial-scale manufacturing of new tungsten-free MMCs and protective coatings with valued service parameters.

A green algae mixture of Scenedesmus and Schroederiella attenuates obesity-linked metabolic syndrome in rats.

This study investigated the responses to a green algae mixture of Scenedesmus dimorphus and Schroederiella apiculata (SC) containing protein (46.1% of dry algae), insoluble fibre (19.6% of dry algae), minerals (3.7% of dry algae) and omega-3 fatty acids (2.8% of dry algae) as a dietary intervention in a high carbohydrate, high fat diet-induced metabolic syndrome model in four groups of male Wistar rats. Two groups were fed with a corn starch diet containing 68% carbohydrates as polysaccharides, while the other two groups were fed a diet high in simple carbohydrates (fructose and sucrose in food, 25% fructose in drinking water, total 68%) and fats (saturated and trans fats from beef tallow, total 24%). High carbohydrate, high fat-fed rats showed visceral obesity with hypertension, insulin resistance, cardiovascular remodelling, and nonalcoholic fatty liver disease. SC supplementation (5% of food) lowered total body and abdominal fat mass, increased lean mass, and attenuated hypertension, impaired glucose and insulin tolerance, endothelial dysfunction, infiltration of inflammatory cells into heart and liver, fibrosis, increased cardiac stiffness, and nonalcoholic fatty liver disease in the high carbohydrate, high fat diet-fed rats. This study suggests that the insoluble fibre or protein in SC helps reverse diet-induced metabolic syndrome.

Polyphenols from green tea prevent antineuritogenic action of Nogo-A via 67-kDa laminin receptor and hydrogen peroxide.

Axonal regeneration after injury to the CNS is hampered by myelin-derived inhibitors, such as Nogo-A. Natural products, such as green tea, which are neuroprotective and safe for long-term therapy, would complement ongoing various pharmacological approaches. In this study, using nerve growth factor-differentiated neuronal-like Neuroscreen-1 cells, we show that extremely low concentrations of unfractionated green tea polyphenol mixture (GTPP) and its active ingredient, epigallocatechin-3-gallate (EGCG), prevent both the neurite outgrowth-inhibiting activity and growth cone-collapsing activity of Nogo-66 (C-terminal domain of Nogo-A). Furthermore, a synergistic interaction was observed among GTPP constituents. This preventive effect was dependent on 67-kDa laminin receptor (67LR) to which EGCG binds with high affinity. The antioxidants N-acetylcysteine and cell-permeable catalase abolished this preventive effect of GTPP and EGCG, suggesting the involvement of sublethal levels of H2 O2 in this process. Accordingly, exogenous sublethal concentrations of H2 O2 , added as a bolus dose (5μM) or more effectively through a steady-state generation (1-2μM), mimicked GTPP in counteracting the action of Nogo-66. Exogenous H2 O2 mediated this action by bypassing the requirement of 67LR. Taken together, these results show for the first time that GTPP and EGCG, acting through 67LR and elevating intracellular sublethal levels of H2 O2 , inhibit the antineuritogenic action of Nogo-A. Currently, several agents are being evaluated for overcoming axonal growth inhibitors to promote functional recovery after stroke and spinal cord injury. Epigallocatechin-3-gallate (EGCG), present in green tea polyphenol mixture (GTPP), prevents antineuritogenic activity of Nogo-A, a myelin-derived axonal growth inhibitor. The preventive action of EGCG involves the cell-surface-associated 67-kDa laminin receptor and H2 O2 . GTPP may complement ongoing efforts to treat neuronal injuries.>

Natural smectitic soils for protective liners in arid climate

Compacted clay liners (CCL) can be used to isolate hazardous wastes like the soil and military scrap contaminated with depleted uranium that emanated from the Iraqi wars in 1991 and 2003. Near-surface repositories for such dangerous waste can preferably be located in the Iraqi deserts, which make up 60% of the territory of Iraq. CCLs are usually constructed using a mixture of clayey soil and coarse material compacted in air-dry form or suitably wetted. In the present study, two smectitic soils from Iraq, termed green and red clays, were investigated for potential use in CCLs. The shear strength, swelling pressure, hydraulic conductivity and creep properties were determined and used for preliminary design of top and bottom-liners. The engineering properties were determined for various dry densities and water contents ranging from air-dry to fully saturated conditions. The results showed that mixtures of sand and 30%–50% green clay and mixtures of sand and 40%–60% red clay are suitable for constructing top-liners with a hydraulic conductivity between 1×10−10 and 1×10−9m/s. For bottom-liners, mixtures of sand and 70% green clay and mixtures of sand and 80% red clay can be considered. They were found to have a hydraulic conductivity of 1×10−11m/s for a density at saturation of 2.1g/cm3 (dry density, 1.7g/cm3). As to the slope stability of top-liners, the shear strength for different clay percentages was found to guarantee slope stability for 18° inclination under both air-dry and water saturated conditions.

Analytical Strategy Coupled with Response Surface Methodology To Maximize the Extraction of Antioxidants from Ternary Mixtures of Green, Yellow, and Red Teas (Camellia sinensis var. sinensis)

This work aimed at using a simplex-centroid design to model the effects of green, yellow, and red tea mixtures (Camellia sinensis var. sinensis) on metal chelation activity, phenolic composition, antioxidant activity, and instrumental taste profile. The regression models that described the extraction of flavan-3-ols, o-diphenols, total phenolic compounds (TPC), free radical scavenging activity toward 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), cupric ion reducing antioxidant activity (CUPRAC), and ferric reducing antioxidant power (FRAP) were significant, and data were fit satisfactorily (R(2) > 80%). A mixture of green and red teas had a synergism in CUPRAC and TPC, whereas a mixture of yellow and red teas had a positive effect on CUPRAC and DPPH. An optimization was performed to maximize the antioxidant activity and flavan-3-ol content and to render a tea with mild bitterness, and results showed that a mixture of 14.81% green, 56.86% yellow, and 28.33% red teas would be the most suitable combination of factors.

Micro infrared spectroscopy discrimination capability of compounds in complex matrices of thin layers in real sample coatings from artworks

The presence of coating on manufactures either to protect them from the environment, or to give them specific properties—as well as simply to change their aspect—has been shown to be a constant practise throughout history. Their characterization is complex not only because of the inherent variability and diversity of the composition, but also due to the small amount of sample material available. A methodology to study those coatings using microFTIR is proposed. In some cases, the use of microSR-FTIR, which heavily increases spatial resolution particularly appropriate for the analysis of these heterogeneous samples, is also proposed. Data processing tools such as distribution maps of specific infrared bands and curve fitting facilitate the interpretation of the spectra and help identify heavily overlapped spectra. Through the identification of individual bands, it has been possible to discriminate materials and comprehend the interaction processes during aging. Infrared spectra from reference aged materials of known production dates and which are essential in understanding those processes are given. A set of selected case studies including materials of different chemical natures and various historical periods are presented: identification of guanine on the inner coating of a hope chest; determination of a protein glue coating from a gilded Baroque altarpiece; assessment of a beeswax superficial application during the historical restoration of a late 19th century canvas painting; identification of impurities of shellac wax in a shellac coating on a wood moulding from a medieval altarpiece; aging and reaction compounds in Pinus resin, drying oil and green copper pigment mixtures used as colour coatings on Baroque and modern desks.

Bioremediation of dyes by fungi isolated from contaminated dye effluent sites for bio-usability.

Biodegradation and detoxification of dyes, Malachite green, Nigrosin and Basic fuchsin have been carried out using two fungal isolates Aspergillus niger, and Phanerochaete chrysosporium, isolated from dye effluent soil. Three methods were selected for biodegradation, viz. agar overlay and liquid media methods; stationary and shaking conditions at 25 °C. Aspergillus niger recorded maximum decolorization of the dye Basic fuchsin (81.85%) followed by Nigrosin (77.47%), Malachite green (72.77%) and dye mixture (33.08%) under shaking condition. Whereas, P. chrysosporium recorded decolorization to the maximum with the Nigrosin (90.15%) followed by Basic fuchsin (89.8%), Malachite green (83.25%) and mixture (78.4%). The selected fungal strains performed better under shaking conditions compared to stationary method; moreover the inoculation of fungus also brought the pH of the dye solutions to neutral from acidic. Seed germination bioassay study exhibited that when inoculated dye solutions were used, seed showed germination while uninoculated dyes inhibited germination even after four days of observation. Similarly, microbial growth was also inhibited by uninoculated dyes. The excellent performance of A. niger and P. chrysporium in the biodegradation of textile dyes of different chemical structures suggests and reinforces the potential of these fungi for environmental decontamination.

A Comparative Study of Pigments from the Wall Paintings of Two Greek Byzantine Churches

The goal of this study was to characterize pigments used in the murals of two Byzantine churches, from Kastoria, northern Greece. The identification of the iconographer was also investigated by comparing the pigments applied in the wall paintings of the churches. Pigment microsamples of various colors were collected and analyzed by environmental scanning electron microscopy coupled with an energy dispersive system to characterize the elemental composition. Raman spectroscopy was employed to collect molecular spectra for characterization of mineralogical phases. Hematite, cinnabar, and minium were identified in red surfaces. Brown and yellow colors were assigned to mixtures of iron oxides, iron hydroxides, and calcite. Mixtures of iron, lead, and mercury compounds were used to produce different hues in the murals. Black tones were prepared primarily using charcoal and bone black. Grey colors were produced by a mixture of black carbon with calcite; blue hues, by a mixture of iron oxides, calcite, and black carbon. The minerals used were similar for both churches. However, the green color was prepared either by green earth or mixtures of iron oxides and calcite. A modern pigment, lithopone, was also determined, demonstrating restoration or overpainting and thus complicating possible correlations. Based on these preliminary results, the wall paintings could not be ascribed to a specific iconographer.

Complex boride metal-matrix composites by SHS under high gravity

Mo2NiB2 and Mo2FeB2 metal-matrix composites (MMCs) were prepared by metallothermic SHS in a centrifugal machine. Our SEM and XRD data suggest that thus synthesized cast materials represent a ductile Ni or Co matrix doped with uniformly distributed inclusions of Mo2NiB2 or W2CoB2 particles. The metal matrix was found to contain grid-type structural elements formed by nickel aluminides. Addition of alloying agents into a green mixture was found to markedly change the microstructure and morphology of resultant MMCs. The Vickers hardness of synthesized MMCs was found to vary between 950 and 1200 HV.

SHS of MAX compounds in the Ti-Si-C system: Influence of mechanical activation

Mechanical activation of Ti-Si-C green mixtures was found to negatively affect the composition, microstructure, and properties of synthesized Ti3SiC2.

Quantifying Responses of Spectral Vegetation Indices to Dead Materials in Mixed Grasslands

Spectral vegetation indices have been the primary resources for characterizing grassland vegetation based on remotely sensed data. However, the use of spectral indices for vegetation characterization in grasslands has been challenged by the confounding effects from external factors, such as soil properties, dead materials, and shadowing of vegetation canopies. Dead materials refer to the dead component of vegetation, including fallen litter and standing dead grasses accumulated from previous years. The abundant dead materials have been presenting challenges to accurately estimate green vegetation using spectral vegetation indices (VIs) derived from remote sensing data in mixed grasslands. Therefore, a close investigation of the relationship between VIs and dead materials is needed. The identified relationships could provide better insight into not only using remote sensing data for quantitative estimation of dead materials, but also the improvement of green vegetation estimation in the mixed grassland that has a high proportion of dead materials. In this article, the spectral reflectance of dead materials and green vegetation mixtures and dead material cover were measured in mixed grasslands located in Grassland National Park (GNP), Saskatchewan, Canada. Nine VIs were derived from the measured spectral reflectance. The relationship between dead material cover and VIs was quantified using the regression model and sensitivity analysis. Results indicated that the relationship between dead material cover and VIs is a function of the amount of dead material cover. Weak positive relationship was found between VIs and dead materials where the cover was less than 50%, and a significant high negative relationship was evident when cover was greater than 50%. When the combined exponential and linear model was applied to fit the negative relationships, more than 90% variation in dead material cover could be explained by VIs. Sensitivity analysis was further applied to the developed models, indicating that sensitivities of all VIs were significant over the entire range of dead material cover except for the triangular vegetation index (TVI), which has insignificant sensitivity when dead material cover was greater than 94%. Among all VIs, the weighted difference vegetation index (WDVI) had the highest sensitivity to changes in dead material cover higher than 50%. The results from this study indicated that vegetation indices based on combination of reflectance in red and NIR bands can be used to estimate dead material cover that is greater than 50%.

Electrothermal explosion in Ti-C mixtures under pressure

122 As is known [1–3], electrothermal explosion (ETE) can be used as a convenient tool for investigat ing the kinetics of rapid high temperature reactions and as a method for fabrication of refractory and com posite materials. In order to provide conditions for more uniform warm up of heterogeneous green mix tures, it seemed reasonable to carry out ETE in condi tions of quasi static compression. By varying an applied pressure, one can expect to get the means for regulating the thermo and electrophysical parameters of starting reactive mixtures. In this communication, we report some results of our study on ETE in Ti–C powder mixtures under pressure.