Green Mixture Research Articles

Combustion synthesis of porous Ti-Co alloys for orthopedic applications

A mechanoactivation of Ti-Co mixtures was used to perform the SHS of Ti-Co alloys without preheating and heat-generating additives. The SHS of Ti-Co alloys from non-activated Ti + Co green mixtures containing an admixture of B4C as a heat-generating agent without preliminary heating was carried out for the first time. The phase composition, structure, and mechanical properties of synthesized materials were explored upon variation in [B4C] within the range 2–10 wt %. The desired structure/properties of combustion products were attained at [B4C] = 2–4 wt %. The materials synthesized under the above optimal conditions exhibited a developed and uniformly distributed system of pores (largely open) with a size of 150–400 μm, at a wall thickness of 70–100 μm. By their properties (interconnected pores in the range 200–500 μm, compression strength 40–65 MPa), the synthesized materials can be recommended for use as metallic scaffolds intended for bone tissue ingrowths.

Fine TiAl and NiAl powders by SHS with a reduction stage

Fine TiAl and NiAl powders have been synthesized by SHS with a reduction stage. Explored was the effect of green composition, stoichiometric ratio, and additives on the particle size, morphology, and phase composition of resultant powders. Addition of NaCl and excessive Mg was found to suppress crystallization. In the presence of heat-generating additives, such as Mg(ClO4)2 and CaO2, the synthesized powders had a particle size of below 3 μm. The morphology and phase composition of synthesized NiAl powders were investigated upon variation in the Al content of green mixture.

Research on suitability of anaerobically treated green waste and sewage sludge mixtures with meat waste for soil fertilization

Research on suitability of anaerobically treated green waste and sewage sludge mixtures with meat waste for soil fertilization

Plasma-arc growth of refractory single crystals from SHS products and green mixtures: an autoreview

Overviewed are the author’s results on the plasma-arc growth of refractory single crystals from SHS products and green mixtures with special emphasis on stability of the growth process.

The Non-coding RNA gadd7 Is a Regulator of Lipid-induced Oxidative and Endoplasmic Reticulum Stress

In obesity and diabetes, an imbalance in fatty acid uptake and fatty acid utilization leads to excess accumulation of lipid in non-adipose tissues. This lipid overload is associated with cellular dysfunction and cell death, which contribute to organ failure, a phenomenon termed lipotoxicity. To elucidate the molecular mechanism of lipid-mediated cell death, we generated and characterized a mutant Chinese hamster ovary cell line that is resistant to palmitate-induced cell death. In this mutant, random insertion of a retroviral promoter trap has disrupted the gene for the non-coding RNA, growth arrested DNA-damage inducible gene 7 (gadd7). Here we report that gadd7 is induced by lipotoxic stress in a reactive oxygen species (ROS)-dependent fashion and is necessary for both lipid- and general oxidative stress-mediated cell death. Depletion of gadd7 by mutagenesis or short hairpin RNA knockdown significantly reduces lipid and non-lipid induced ROS. Furthermore, depletion of gadd7 delays and diminishes ROS-induced endoplasmic reticulum stress. Together these data are the first to implicate a non-coding RNA in a feed-forward loop with oxidative stress and its induction of the endoplasmic reticulum stress response.

Regulation of Epidermal Growth Factor Receptor Signaling in Human Cancer Cells by MicroRNA-7

The epidermal growth factor receptor (EGFR) is frequently overexpressed in cancer and is an important therapeutic target. Aberrant expression and function of microRNAs have been associated with tumorigenesis. Bioinformatic predictions suggest that the human EGFR mRNA 3'-untranslated region contains three microRNA-7 (miR-7) target sites, which are not conserved across mammals. We found that miR-7 down-regulates EGFR mRNA and protein expression in cancer cell lines (lung, breast, and glioblastoma) via two of the three sites, inducing cell cycle arrest and cell death. Because miR-7 was shown to decrease EGFR mRNA expression, we used microarray analysis to identify additional mRNA targets of miR-7. These included Raf1 and multiple other genes involved in EGFR signaling and tumorigenesis. Furthermore, miR-7 attenuated activation of protein kinase B (Akt) and extracellular signal-regulated kinase 1/2, two critical effectors of EGFR signaling, in different cancer cell lines. These data establish an important role for miR-7 in controlling mRNA expression and indicate that miR-7 has the ability to coordinately regulate EGFR signaling in multiple human cancer cell types.

Comparison of yields and nutritive value of different spring green forage mixtures

To achieve a more efficient system of green feeding it is necessary to introduce new field cropping species in ruminant nutrition as green forage is which nutritional value has not been exactly evaluated yet. In our researches we analysed the yields and nutritive value of different spring green forage mixtures. We concluded that green forage mixtures gave more green and crude protein yield than the average of the components, and the nutritive value of the mixtures was better than the components’ nutritive value. In the average of three years, the dry matter content in the mixtures was similar to each other at the start of flowering. In our research the measured dry matter content in mixtures was higher than pea mixed with sunflower from literature and pea mixed with oat. The difference between vetch mixed with oat and the analyzed pea and barley mixture was 29 g/kg. Pea can give almost the same crude protein yield level than pea with oat and pea with spring barley. Based on achieved results it can be concluded that pea was a reliable component with barley and oat even in extreme weather conditions and in spring mixtures with barley or oat, the vegetative types of pea are recommended as leguminous component instead of using the “traditional” vetches, with special regard to the crude protein content.

Combustion and structure formation in the mechanoactivated Cr-B system

For Cr + B mixtures, we investigated the influence of mechanoactivation (MA) on the thermal effect of SHS reaction, burning velocity, and combustion temperature, and optimized MA conditions. Using the technique of forced SHS compaction, we manufactured the CrB2-based compacts up to 125 mm in diameter (residual porosity 3–5%) from green mixtures subjected to MA under optimized conditions.

Thermomechanical and thermodilatometric analysis of green alumina porcelain

A modulated force thermomechanical analysis (mf-TMA) and thermodilatometric analysis (TDA) of the green ceramic mixture of kaolin (27 wt.%), Al 2O 3 (50 wt.%) and feldspar (23 wt.%) up to 1000 °C is presented. The mf-TMA reflects changes during heating the green ceramics with higher sensitivity than TDA. Discrepancies between mf-TMA and TDA revealed that the elastic behavior of the green porcelain samples is determined most importantly by processes on the crystal boundaries (escaping of the water molecules at the low temperatures up to 150 °C and solid state sintering at the temperatures above 450 °C). Processes in the crystal interiors (e.g. dehydroxylation) have a lesser function. Thermodilatometric results depend more on the processes which take place inside the crystals than on the processes on the crystal surfaces.

Modification of gamma‐radiation response in mice by green tea polyphenols

In this study we evaluated the effect of water extracts of green tea (GT) and mixtures of green tea polyphenols (GTPs), epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and epicatechin (EC) on jejunal crypt survival, endogenous spleen colony formation, and apoptosis in jejunal crypt cells of mice irradiated with gamma-ray. The radioprotective effect of green tea was compared with the effect of diethyldithiocarbamate (DDC). Jejunal crypts were protected by pretreatment of GT and ECG. Administration of GT, GTPs and EC prior to irradiation resulted in an increase in the formation of endogenous spleen colonies. The frequency of apoptosis in crypt cells was also reduced by pretreatment of GT, GTPs, EGCG, ECG and EGC. In the experiment on the effect of catechins, the effects were partly contradicted in irradiated mice. The rank order of activity was ECG > EGC > EGCG > EC on intestinal crypt survival assay, EC > EGC > ECG > EGCG on the spleen colony formation assay, EGCG > EGC > EC > ECG on inhibiting the death of cells caused by apoptosis. The results indicate that GT and GTPs may have a major radioprotective effect. Each one of the catechins was a much less effective radioprotector, suggesting that total extract or a mixture of GTPs may be more effective than individual catechins.

Cold uniaxial compaction of Ti-containing powders: Rheological aspects

Pre-compaction of powder mixtures by cold pressing is being widely used in numerous areas of modern science and technology, including SHS. Normally, the process is being carried out at constant pressure ( P = const), so that the calibration plot in the coordinates pressure‐density (porosity) is obtained in a series of experiments at different P [1]. In this communication, we suggest to determine the calibration plot of a given press facility in one experimental run performed at a constant velocity of plunger feed V p . As a model, we used Ti + B and Ti + C + Ni powder mixtures. These mixtures were used as green mixtures in SHS extrusion of electrodes for electrospark alloying [2]. Powder compositions were as follows: 20 wt % Ti + 80 wt % B and 56 wt % Ti + 14 wt % C + 30 wt % Ni. Experiments were carried out in an INSTRON apparatus at constant V p (5 mm min ‐1 ) at a load up to 10 t (determined with an accuracy of 1%).

Reactive sintering of Ti-Al and Ti-Al-Nb consolidated elemental blocks for use as consumable electrodes in vacuum arc melting

Explored was the feasibility of fabricating consolidated elemental blocks (CEBs) Ti-36Al and Ti-29Al-18Nb (wt %) via reactive sintering for their use as consumable electrodes in vacuum arc melting (VAM). For obtaining strong blocks in the Ti-Al system, thermal treatment of green mixture must be performed at a temperature not less that 700°C, which is then followed by sintering at 1100°C. In Nb-containing mixtures, the exothermic effect is less pronounced, so that thermal treatment must be carried out at 1300°C. The presence of free Al is a prerequisite for reactive sintering. It has been established experimentally that the Al content of green mixture must be above 10 wt %.

Combustion and structure formation in the Ti-Ta-C-Ca3(PO4)2 system

Biocompatible composites (Ti, Ta)Cx + Ca3(PO4)2 for deposition of nanofilms onto load-bearing implants by ion-plasma sputtering were prepared from Ti + Ta + C + Ca3(PO4)2 mixtures by forced SHS compaction. The effect of Ta + C addition to green mixtures (characterized by parameter z) on the structure/phase formation in combustion products was explored. The addition of tantalum and carbon was found to have little or no influence on the burning velocity U and combustion temperature Tc. Two thermal spikes exhibited by thermograms were associated with the occurrence of two consecutive reactions leading to formation of titanium and tantalum carbides. With increasing z, the grain size of (Ti, Ta)C was found to diminish, its relative density to decrease, while the hardness to markedly grow.

Evaluating the growth characteristics of lettuce in vermicompost and green waste compost

Vermicompost was produced from a green waste compost feedstock and assessed for its potential use in a high value horticultural market. Replicated plant growth trials were undertaken with lettuce using pure worm cast (vermicompost), green waste-derived compost and mixtures of the two, i.e. 50/50 (v/v) and 20/80 (v/v) of worm casts and green waste feedstock. Results showed that plant biomass production was optimal with a 20/80 (v/v) compost blend, whilst pure worm cast and green waste compost yielded poor growth. Leaf chlorophyll content indicated that pure worm cast inhibited plant growth and depressed N content, whereas plant grown with the other treatments contained similar amounts of chlorophyll. In general, the vermicomposting process did not result in an increased availability of nutrients or potentially toxic elements, the only exception being Zn.

Distinct Uptake Mechanisms but Similar Intracellular Processing of Two Different Toll-like Receptor Ligand-Peptide Conjugates in Dendritic Cells

Covalent conjugation of Toll-like receptor ligands (TLR-L) to synthetic antigenic peptides strongly improves antigen presentation in vitro and T lymphocyte priming in vivo. These molecularly well defined TLR-L-peptide conjugates, constitute an attractive vaccination modality, sharing the peptide antigen and a defined adjuvant in one single molecule. We have analyzed the intracellular trafficking and processing of two TLR-L conjugates in dendritic cells (DCs). Long synthetic peptides containing an ovalbumin cytotoxic T-cell epitope were chemically conjugated to two different TLR-Ls the TLR2 ligand, Pam(3)CysSK(4) (Pam) or the TLR9 ligand CpG. Rapid and enhanced uptake of both types of TLR-L-conjugated peptide occurred in DCs. Moreover, TLR-L conjugation greatly enhanced antigen presentation, a process that was dependent on endosomal acidification, proteasomal cleavage, and TAP translocation. The uptake of the CpG approximately conjugate was independent of endosomally-expressed TLR9 as reported previously. Unexpectedly, we found that Pam approximately conjugated peptides were likewise internalized independently of the expression of cell surface-expressed TLR2. Further characterization of the uptake mechanisms revealed that TLR2-L employed a different uptake route than TLR9-L. Inhibition of clathrin- or caveolin-dependent endocytosis greatly reduced uptake and antigen presentation of the Pam-conjugate. In contrast, internalization and antigen presentation of CpG approximately conjugates was independent of clathrin-coated pits but partly dependent on caveolae formation. Importantly, in contrast to the TLR-independent uptake of the conjugates, TLR expression and downstream TLR signaling was required for dendritic cell maturation and for priming of naïve CD8(+) T-cells. Together, our data show that targeting to two distinct TLRs requires distinct uptake mechanism but follows similar trafficking and intracellular processing pathways leading to optimal antigen presentation and T-cell priming.

SHS reactions in the NiO-Al system: Influence of stoichiometry

Thermite reactions in the NiO-Al system have been studied. In addition to the case when the stoichiometry is set up to produce metallic nickel and alumina, we studied the case when Al is added in excess in order to react with the Ni produced through the reduction of nickel monoxide with Al to produce various nickel aluminides. As thermite reactions are highly exothermic, in order to provide a better understanding of the reactions, alumina has been added to the green mixture to reduce the reaction rate and overall exothermicity, in amounts corresponding up to 50% of the overall heat capacity of the sample.

Interaction between HIV-1 Rev and Integrase Proteins

Human immunodeficiency virus 1 (HIV-1) Rev and integrase (IN) proteins are required within the nuclei of infected cells in the late and early phases of the viral replication cycle, respectively. Here we show using various biochemical methods, that these two proteins interact with each other in vitro and in vivo. Peptide mapping and fluorescence anisotropy showed that IN binds residues 1-30 and 49-74 of Rev. Following this observation, we identified two short Rev-derived peptides that inhibit the 3'-end processing and strand-transfer enzymatic activities of IN in vitro. The peptides bound IN in vitro, penetrated into cultured cells, and significantly inhibited HIV-1 in multinuclear activation of a galactosidase indicator (MAGI) and lymphoid cultured cells. Real time PCR analysis revealed that the inhibition of HIV-1 multiplication is due to inhibition of the catalytic activity of the viral IN. The present work describes novel anti-HIV-1 lead peptides that inhibit viral replication in cultured cells by blocking DNA integration in vivo.

On the Progress of Combustion Synthesis of Si<sub>3</sub>N<sub>4</sub> Ceramic: From Laboratory Research to Industrial Production

The progress on the combustion synthesis of Si3N4 powders during the past decades was summarized with the emphasis on the recently developed mechano-chemically activated combustion synthesis (MACS) method. The effects of processing parameters such as the addition of diluent and ammonium salts into the green mixtures, the variation of nitrogen pressure as well as the mechanical activation treatment on the degree of Si to α-Si3N4 conversion was evaluated. The combination of mechanical activation and chemical stimulation was effective in enhancing the reactivity of Si powder reactants, which was responsible for the extension of the minimum nitrogen pressure normally required for the combustion synthesis of Si3N4. This breakthrough indicates that nitriding combustion of silicon in pressurized nitrogen could be promoted by activating the solid reactants instead of by increasing the pre-exerted nitrogen pressure. The MACS process was successfully applied to the industrial production of Si3N4 powders, the regularities for the large-scale synthesis were reported, and the as-synthesized Si3N4 powder products were systematically characterized.

Transforming Growth Factor-β Receptor Type I-dependent Fibrogenic Gene Program Is Mediated via Activation of Smad1 and ERK1/2 Pathways

The transforming growth factor (TGF)-beta/Smad3 signaling pathway is considered a central mediator of pathological organ fibrosis; however, contribution of Smad2/3-independent TGF-beta signaling has not been fully explored. The present study utilized previously a described model of scleroderma (SSc) fibrosis based on forced expression of the TGF-betaRI (ALK5) (Pannu, J., Gardner, H., Shearstone, J. R., Smith, E., and Trojanowska, M. (2006) Arthritis Rheum. 54, 3011-3021). This study was aimed at determining the molecular mechanisms underlying the profibrotic program in this model. We demonstrate that the TGF-betaRI-dependent up-regulation of collagen and CCN2 (CTGF) does not involve Smad2/3 activation but is mediated by ALK1/Smad1 and ERK1/2 pathways. The following findings support this conclusion: (i) Smad2 and -3 were not phosphorylated in response to TGF-betaRI, (ii) a TGF-betaRI mutant defective in Smad2/3 activation, ALK5(3A), potently stimulated collagen production, (iii) elevation of TGF-betaRI triggered sustained association of ALK5 with ALK1 and high levels of Smad1 phosphorylation, (iv) blockade of Smad1 via small interfering RNA abrogated collagen and CCN2 up-regulation in this model, (v) elevated TGF-betaRI led to a prolonged activation of ERK1/2, (vi) the pharmacologic inhibitor of ERK1/2 inhibited Smad1 phosphorylation and abrogated profibrotic effects of elevated TGFbeta-RI. Additional experiments demonstrated that a GC-rich response element located -6 to -16 (upstream of the transcription start site) in the CCN2 promoter mediated Smad1-dependent increased promoter activity in this model. This element was shown previously to mediate up-regulation of the CCN2 promoter in SSc fibroblasts. In conclusion, this study defines a novel ALK1/Smad1- and ERK1/2-dependent, Smad3-independent mode of TGF-beta signaling that may operate during chronic stages of fibrosis in SSc.

Combustion of the Fe-Si alloy in nitrogen gas

Combustion of the Fe-Si alloy in nitrogen gas was explored. The combustion was found to proceed in an autooscillating mode. Upon addition of nitrided ferrosilicon, magnesium fluoride, or ammonium chloride into a green mixture, the process becomes steady-state, while the extent of nitriding attains its maximum value. The phase composition and morphology of the product were found to depend on reaction conditions. The products formed in the presence of ferrosilicon or magnesium fluoride were found to largely contain columnar, platelike, and whiskerlike β-Si3N4 crystals (≥95%), while those in the presence of ammonium chloride contain silicon nitride with a granular structure and elevated content of the α-phase (<80%). Acid enrichment of combustion products was used to obtain silicon nitride with a Fe content of 0.01–0.1 wt %.