Compaction Of Matrix Research Articles

Electronic Coherences Excited by an Ultra Short Pulse Are Robust with Respect to Averaging over Randomly Oriented Molecules as Shown by Singular Value Decomposition.

We report a methodology for averaging quantum photoexcitation vibronic dynamics over the initial orientations of the molecules with respect to an ultrashort light pulse. We use singular value decomposition of the ensemble density matrix of the excited molecules, which allows the identification of the few dominant principal molecular orientations with respect to the polarization direction of the electric field. The principal orientations provide insights into the specific stereodynamics of the corresponding principal molecular vibronic states. The massive compaction of the vibronic density matrix of the ensemble of randomly oriented pumped molecules enables a most efficient fully quantum mechanical time propagation scheme. Two examples are discussed for the quantum dynamics of the LiH molecule in the manifolds of its electronically excited Σ and Π states. Our results show that electronic and vibrational coherences between excited states of the same symmetry are resilient to averaging over an ensemble of molecular orientations and can be selectively excited at the ensemble level by tuning the pulse parameters.

UV-Excited Luminescence in Porous Organosilica Films with Various Organic Components.

UV-induced photoluminescence of organosilica films with ethylene and benzene bridging groups in their matrix and terminal methyl groups on the pore wall surface was studied to reveal optically active defects and understand their origin and nature. The careful selection of the film's precursors and conditions of deposition and curing and analysis of chemical and structural properties led to the conclusion that luminescence sources are not associated with the presence of oxygen-deficient centers, as in the case of pure SiO2. It is shown that the sources of luminescence are the carbon-containing components that are part of the low-k-matrix, as well as the carbon residues formed upon removal of the template and UV-induced destruction of organosilica samples. A good correlation between the energy of the photoluminescence peaks and the chemical composition is observed. This correlation is confirmed by the results obtained by the Density Functional theory. The photoluminescence intensity increases with porosity and internal surface area. The spectra become more complicated after annealing at 400 °C, although Fourier transform infrared spectroscopy does not show these changes. The appearance of additional bands is associated with the compaction of the low-k matrix and the segregation of template residues on the surface of the pore wall.

Spatiotemporal control of myofibroblast activation in acoustically-responsive scaffolds via ultrasound-induced matrix stiffening

Hydrogels are often used to study the impact of biomechanical and topographical cues on cell behavior. Conventional hydrogels are designed a priori, with characteristics that cannot be dynamically changed in an externally controlled, user-defined manner. We developed a composite hydrogel, termed an acoustically-responsive scaffold (ARS), that enables non-invasive, spatiotemporally controlled modulation of mechanical and morphological properties using focused ultrasound. An ARS consists of a phase-shift emulsion distributed in a fibrin matrix. Ultrasound non-thermally vaporizes the emulsion into bubbles, which induces localized, radial compaction and stiffening of the fibrin matrix. In this in vitro study, we investigate how this mechanism can control the differentiation of fibroblasts into myofibroblasts, a transition correlated with substrate stiffness on 2D substrates. Matrix compaction and stiffening was shown to be highly localized using confocal and atomic force microscopies, respectively. Myofibroblast phenotype, evaluated by α-smooth muscle actin (α-SMA) immunocytochemistry, significantly increased in matrix regions proximal to bubbles compared to distal regions, irrespective of the addition of exogenous transforming growth factor-β1 (TGF-β1). Introduction of the TGF-β1 receptor inhibitor SB431542 abrogated the proximal enhancement. This approach providing spatiotemporal control over biophysical signals and resulting cell behavior could aid in better understanding fibrotic disease progression and the development of therapeutic interventions for chronic wounds. Statement of SignificanceHydrogels are used in cell culture to recapitulate both biochemical and biophysical aspects of the native extracellular matrix. Biophysical cues like stiffness can impact cell behavior. However, with conventional hydrogels, there is a limited ability to actively modulate stiffness after polymerization. We have developed an ultrasound-based method of spatiotemporally-controlling mechanical and morphological properties within a composite hydrogel, termed an acoustically-responsive scaffold (ARS). Upon exposure to ultrasound, bubbles are non-thermally generated within the fibrin matrix of an ARS, thereby locally compacting and stiffening the matrix. We demonstrate how ARSs control the differentiation of fibroblasts into myofibroblasts in 2D. This approach could assist with the study of fibrosis and the development of therapies for chronic wounds.

Dynamics of pathomorphological changes in the structural organization of the intervertebral disc at the end of the seventh and fourteenth day of experimental opioid exposure at the ultrastructural level

In general, the modern literature pays attention to the issues of spine pathology and intervertebral discs. A significant percentage of vertebral disorders - scoliosis, osteochondrosis, spinal disc herniation, etc., occur as a result of exposure to various factors and manifest in changes of the intervertebral discs. The aim of our work was to study at the ultrastructural level the features of pathomorphological manifestations in the structural components of the intervertebral disc at the end of the seventh and fourteenth days of experimental opioid exposure. Materials and methods of research. The objects of the study were 32 sexually mature, white, male rats, weighing 92 - 103 g, aged 4.5 months. Animals were injected with nalbupine intramuscularly once daily (at 10-11 a.m.) for 14 days. The initial dose of nalbuphine was 8 mg/kg during the first week, 15 mg/kg during the second week. It created the conditions of chronic opioid exposure. Before sampling, the animals were withdrawn from the experiment using dibutyl ether. Intervertebral discs of rats were used as a material for ultrastructural study. Ultrastructural specimens were prepared according to the accepted methods. The results of the study. As a result of the sampling after 7 days of opioid exposure we found inhomogeneous osmiophilicity and compaction of the nucleus pulposus matrix in which intensively accumulated osmiophilic grains of glycogen proteoglycans, increased the number of collagen fibers, some of them were heterogeneous. It was also noted the development of moderate degenerative changes in some notochondral cells, which was accompanied by increased vacuolization of the cytoplasm by inhomogeneous compaction of the nucleus and an increase of heterochromatin there. After 14 days necrotic changes in the cells of the nucleus pulposus, as well as the destruction of collagen fibers of the annulus fibrosus were found. In particular, an increase in the amount of heterochromatin in the nucleui of notochondral cells, which was accompanied by a decrease in the volume of the nucleui and inhomogeneous swelling of the cytoplasm. Active fibroblasts were often visualized in the annulus fibrosus. Intense osmiophilicity and thickening of collagen fibers of the annulus fibrosus were observed in some areas of the fibrous ring. Focal destruction of collagen fibers was also noted. In the areas of destruction the fibrils of collagen fibers disintegrated into an inhomogeneous fine-grained stratified mass and were located loosely. Conclusions. At the end of the first week we found that the cytoplasmic processes of chondrocytes decreased in volume, shortened, underwent fragmentation and destruction, some of them detached from the surface of the plasmolemma. At the end of the second week signs of opioid exposure progressed and manifested by an increase in the destruction of cytoplasmic processes in chondrocytes. Also focal destruction of collagen fibers was noted.

Sustainable low-carbon binders and concretes

Sustainable development depends on a consistency of interests, social, ecological and economic, and that the interests are evaluated in a balanced manner. In order to reduce CO2 emissions, the conception of decreasing clinker factor and increasing the role of supplementary cementitious materials (SCMs) in the cementitious materials has high economical and environmental efficiency. The performance of clinkerefficient blended cements with supplementary cementitious materials were examined. The influence of superfine zeolite with increased surface energy on the physical and chemical properties of low-carbon blended cements is shown. Increasing the dispersion of cementitious materials contributes to the growth of their strength activity index due to compaction of cement matrix and pozzolanic reactions in unclincker part. In consequence of the early structure formation and the directed formation of the microstructure of the cement matrix is solving the problem of obtaining clinker-efficient concretes. Shown that low-carbon blended cements with high volume of SCMs are suitable, in principle, for producing structural concretes.

Influence of Nanosilica on Mechanical Properties, Sorptivity, and Microstructure of Lightweight Concrete.

This study presents the results of an experimental investigation of the effects of nanosilica (NS) on the strength development, transport properties, thermal conductivity, air-void, and pore characteristics of lightweight aggregate concrete (LWAC), with an oven-dry density <1000 kg/m3. Four types of concrete mixtures, containing 0 wt.%, 1 wt.%, 2 wt.%, and 4 wt.% of NS were prepared. The development of flexural and compressive strengths was determined for up to 90 days of curing. In addition, transport properties and microstructural properties were determined, with the use of RapidAir, mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) techniques. The experimental results showed that NS has remarkable effects on the mechanical and transport properties of LWACs, even in small dosages. A significant improvement in strength and a reduction of transport properties, in specimens with an increased NS content, was observed. However, the positive effects of NS were more pronounced when a higher amount was incorporated into the mixtures (>1 wt.%). NS contributed to compaction of the LWAC matrix and a modification of the air-void system, by increasing the amount of solid content and refining the fine pore structure, which translated to a noticeable improvement in mechanical and transport properties. On the other hand, NS decreased the consistency, while increasing the viscosity of the fresh mixture. An increment of superplasticizer (SP), along with a decrement of stabilizer (ST) dosages, are thus required.

The Effect of Chitosan Derivatives on the Compaction and Tension Generation of the Fibroblast-populated Collagen Matrix.

Fibrotic diseases, such as Dupuytren’s contracture (DC), involve excess scar tissue formation. The differentiation of fibroblasts into myofibroblasts is a significant mechanism in DC, as it generates tissue contraction in areas without wound openings, leading to the deposition of scar tissue, and eventually flexing one or more fingers in a restrictive fashion. Additionally, DC has a high recurrence rate. Previously, we showed that N-dihydrogalactochitosan (GC), an immunostimulant, inhibited myofibroblast differentiation in a DC fibroblast culture. Our goal of this study was to expand our previous study to include other DC and normal cell lines and other chitosan derivatives (GC and single-walled carbon nanotube-conjugated GC) to determine the specific mechanism of inhibition. Derivative-incorporated and vehicle control (water) anchored fibroblast-populated collagen matrices (aFPCM) were used to monitor compaction (anchored matrix height reduction) using microscopy and optical coherence tomography (OCT) for six days. Fibroblasts were unable to compact chitosan derivative aFPCM to the same extent as vehicle control aFPCM in repeated experiments. Similarly, chitosan derivative aFPCM contracted less than control aFPCM when released from anchorage. Proliferative myofibroblasts were identified by the presence of alpha smooth muscle actin via myofibroblast proliferative assay. In all tested conditions, a small percentage of myofibroblasts and proliferative cells were present. However, when aFPCM were treated with transforming growth factor-beta 1 (TGF-β1), all tested samples demonstrated increased myofibroblasts, proliferation, compaction, and contraction. Although compaction and contraction were reduced, there was sufficient tension present in the chitosan derivative aFPCM to allow exogenous stimulation of the myofibroblast phenotype.

Permeability and Surface Hardness Surveying of Stone Damaged by Ballistic Impact

Recent instances of the destruction of cultural assets in conflict zones have demonstrated the need to develop methods which will allow for the assessment of damage to heritage stone in the field. In particular, non-destructive methods would be invaluable when working on sites damaged by contemporary ballistics. Permeability (TinyPerm 3) and surface hardness (Equotip) surveys of stone damaged by 7.62 × 39 mm (AK-47) projectiles were undertaken to determine the ability of these methods to identify the spatial distribution of damage patterns such as shear faces and surface fractures. Results demonstrate the ability of surface hardness surveys to distinguish between non-impacted surfaces of the target stone and surfaces which shattered/sheared upon impact. Whilst spatial distribution analysis (“heat mapping”) of Equotip data did not correlate directly with surface fractures, permeability data heat maps were found to be indicative of surface fracture distribution. The data suggests that compaction of the stone matrix at the impact crater results in a lesser reduction of hardness in this area relative to the wider damaged surface. Surveys of impacted stone using the methods outlined here can identify damage patterns that are not visible to the naked eye, thus aiding in damage identification on fragile sites.

On the Timescale of Magma Ocean Solidification and Its Chemical Consequences: 2. Compositional Differentiation Under Crystal Accumulation and Matrix Compaction

AbstractThe solidification of a putative magma ocean sets the stage for subsequent subsolidus mantle convection. Whereas it may have resulted in a compositionally stratified mantle, the efficiency of relevant processes to cause chemical differentiation, such as crystal accumulation and matrix compaction, remains uncertain. The purpose of this study is to present the thermochemical structure of end‐member cases where potential differentiation mechanisms are taking full effect. We employ a self‐consistent thermodynamic model to make our model consistent in both thermal and chemical aspects. The accumulation of crystals at the base of magma ocean can enrich the upper mantle with iron, but such a global‐scale compositional stratification is likely to be quickly eliminated by gravitational instability, leaving small‐scale heterogeneities only. On the other hand, the compaction of solid matrix in the deep mantle creates a long‐lasting molten layer above the core‐mantle boundary. Our results suggest that the efficiency of compaction is the key factor to generate compositional stratification during solidification.

Compaction, degradation and deformation characteristics of an energy absorbing matrix

Abstract The reuse of waste materials as an alternative to natural aggregates is becoming more popular in engineering projects. It offers a sustainable and economical solution to address the environmental concerns arising from the scarcity of natural quarries as well as the increase in waste generation. Coal wash (CW) and rubber crumbs (RC) are industrial by-products that could potentially be used in railway substructures. In this study, different RC levels are introduced into CW (i.e. CWRC mixture) to reduce potential breakage of CW and increase the ductility and energy absorbing capacity of the matrix. The compaction and degradation characteristics of CWRC mixtures to be used as a construction fill are investigated under five energy levels ranging from standard to modified Proctor compaction. An optimum compaction energy is determined so as to minimize breakage but still yield an acceptable void ratio (compact packing) to avoid excessive settlements. The compressibility of rubber particles and the induced change in the volume of solids is addressed with regard to the overall void ratio of the matrix. Furthermore, the results of triaxial tests on four CWRC mixtures compacted to the same void ratio under three different confining pressures (25, 50 and 75 kPa) are presented, and the effect of RC content on the stress-strain relationship is elucidated.

Predictable fibroblast tension generation by measuring compaction of anchored collagen matrices using microscopy and optical coherence tomography

ABSTRACTThe anchored fibroblast-populated collagen matrix (aFPCM) is an appropriate model to study fibrocontractive disease mechanisms. Our goal was to determine if aFPCM height reduction (compaction) during development is sufficient to predict tension generation. Compaction was quantified daily by both traditional light microscopy and an optical coherence tomography (OCT) system. Contraction in aFPCM was revealed by releasing them from anchorage. We found that aFPCM contraction increase was correlated to the compaction increase. Cytochalasin D treatment reversibly inhibited compaction. Therefore, we demonstrated that aFPCM height reduction efficiently measures compaction, contraction, and relative maturity of the collagen matrix during development or treatment. In addition, we showed that OCT is suitable for effectively imaging the cross-sectional morphology of the aFPCM in culture. This study will pave the way for more efficient studies on the mechanisms of (and treatments that target) migration and contraction in wound healing and Dupuytren’s contracture in a tissue environment.

Effects of fluid influx, fluid viscosity, and fluid density on fluid migration in the mantle wedge and their implications for hydrous melting

The migration pathways of hydrous fluids in the mantle wedge are influenced by the compaction of the porous mantle matrix, which depends on the matrix permeability, fluid viscosity, and fluid density. Experimental studies show that when fluids are interconnected, the permeability depends on mineral grain size and porosity, the latter of which depends on the amount of fluids introduced into the system (fluid influx). Here, we investigate the role of fluid influx, fluid viscosity, and fluid density in controlling fluid migration in the mantle wedge, using a 2-D numerical model accounting for the effects of grain-size variation and matrix compaction. Our models predict that fluid influx and fluid viscosity are key controls on fluid pathways, while fluid density plays a secondary role. Temperature dependence of fluid viscosity promotes downdip drag of fluids at the base of the forearc mantle toward the subarc region. High fluid influx at postarc depths promotes updip flow near the base of the mantle wedge, guiding the fluids arcward. The model that is applied to northern Cascadia predicts upward fluid migration focused beneath the arc but cannot explain high electrical conductivity observed slightly west of the upward fluid migration. We estimate the amount of hydrous melt that can be produced in the mantle wedge using calculated fluid distributions. Up to a few percent partial melting is predicted in a relatively small region in the core part of the subarc mantle wedge in most subduction settings, including northern Cascadia, and beneath the backarc in old-slab subduction zones.

Dehydration improves biomechanical strength of bioartificial vascular graft material and allows its long-term storage.

IntroductionWe have recently reported about a novel technique for the generation of bioartificial vascular grafts based on the use of a compacted fibrin matrix. In this study, we evaluated the effects of a dehydration process on the biomechanical properties of compacted fibrin tubes and whether it allows for their long-term storage.Materials and methodsFibrin was precipitated from fresh frozen plasma by means of cryoprecipitation and simultaneously with a thrombin solution applied in a high-speed rotating casting mold. Subsequent dehydration of the fibrin tubes (29/38) was performed in dry air with a dilator inside the tube to prevent the collapse of the lumen. Dehydrated fibrin tubes were stored for six (n=9) and 12 months (n=10) at room temperature. Comparative analysis was done on initially generated and dehydrated fibrin tubes before and after storage to evaluate the effects of the dehydration process and storage on the biomechanical properties and structure of the tubes.ResultsThirty-eight fibrin tubes were generated by high-speed rotation-molding from 142±3 mg fibrinogen with an inner diameter of 5.8±0.1 mm and a length of 100 mm. A centrifugal force of nearly 900×g compacted applied fibrin, while fluid was pressed out of the matrix and drained from the mold via holes resulting in a 16-fold compaction of the fibrin matrix. Dehydration was characterized by shrinkage of the tubes to a diameter of 3.2±0.2 mm, while the length remained at 100 mm equivalent to a further two-fold compaction. The biomechanical strength of the dehydrated fibrin tubes significantly increased to values comparable to that of native ovine carotid arteries and maintained during the first 6 months of storage. After 12 months of storage, only five of 10 tubes were intact, and only one showed maintained biomechanical strength.DiscussionCompaction of a fibrin matrix in high-speed rotation-moulding and subsequent dehydration enables for the construction of small-caliber fibrin grafts. Over and above, the dehydration process allows their storage and stockpiling as a prerequisite for clinical use.

Experimental investigations of internal energy dissipation during fracture of fiber-reinforced ultra-high-performance concrete

Split-cylinder fracture of fiber-reinforced ultra-high-performance concrete (UHPC) was examined using two complementary techniques: X-ray computed tomography (CT) and acoustic emission (AE). Fifty-mm-diameter specimens of two different fiber types were scanned both before and after load testing. From the CT images, fiber orientation was evaluated to establish optimum and pessimum specimen orientations, at which fibers would have maximum and minimum effect, respectively. As expected, fiber orientation affected both the peak load and the toughness of the specimen, with the optimum toughness being between 20% and 30% higher than the pessimum. Cumulative AE energy was also affected commensurately. Posttest CT scans of the specimens were used to measure internal damage. Damage was quantified in terms of internal energy dissipation due to both matrix cracking and fiber pullout by using calibration measurements for each. The results showed that fiber pullout was the dominant energy dissipation mechanism; however, the sum of the internal energy dissipation measured amounted to only 60% of the total energy dissipated by the specimens as measured by the net work of load. It is postulated that localized compaction of the UHPC matrix as well as internal friction between fractured fragments makes up the balance of internal energy dissipation.

Engineered Tissue Folding by Mechanical Compaction of the Mesenchyme

Many tissues fold into complex shapes during development. Controlling this process invitro would represent an important advance for tissue engineering. We use embryonic tissue explants, finite element modeling, and 3D cell-patterning techniques to show that mechanical compaction of the extracellular matrix during mesenchymal condensation is sufficient to drive tissue folding along programmed trajectories. The process requires cell contractility, generates strains at tissue interfaces, and causes patterns of collagen alignment around and between condensates. Aligned collagen fibers support elevated tensions that promote the folding of interfaces along paths that can be predicted by modeling. We demonstrate the robustness and versatility of this strategy for sculpting tissue interfaces by directing the morphogenesis of a variety of folded tissue forms from patterns of mesenchymal condensates. These studies provide insight into the active mechanical properties of the embryonic mesenchyme and establish engineering strategies for more robustly directing tissue morphogenesis exvivo.

Material composition, pore structure and adsorption capacity of low-rank coals around the first coalification jump: A case of eastern Junggar Basin, China

The first coalification jump (FCJ) has a significant impact on low-rank coal reservoir heterogeneity, and is of great importance for coalbed methane (CBM) development. Here, a series of experiments were performed for 10 coal samples collected from eastern Junggar Basin, to compare the material composition, pore structure and adsorption capacity of lignite and candle coal. Contrast with the candle coal, the lignite has a higher inertinite content, larger pore volume, better connectivity, and greater specific surface area (SSA). During the process of FCJ, the polycondensation of coal molecules and the compaction of coal matrix occur, leading to a rapid decline of moisture, porosity and permeability, and the cell wall in the candle coal is badly crushed with clay minerals filled from optical microscopy. In general, the larger total pore volume (1.7–300 nm, measured by N2 adsorption) contributes to the larger SSA. The SSA of candle coal mainly comes from the contribution of micropore (<10 nm), especially the 2–3 nm pores, while the micropore and transition pore (10–100 nm) contribute to most of SSA of lignite. However, though the SSA of the candle coal is largely lower than that of the lignite, the CH4 adsorption capacity tends to decrease from the lignite to the candle coal due to material composition difference. Low-field NMR was used to determine the pore and fracture system by analyzing the transverse relaxation time, which showed that only two obvious peaks could be identified in lignite and three peaks at about 0.25 ms, 30 ms and 200 ms are present in the candle coal. The fractal results indicate that the pore surface and complexity inside the coal increase gradually from lignite to candle coal. These observations could deepen awareness and understanding of low-rank coal reservoir heterogeneity and the influence of FCJ on reservoir property.

Clay, Water, and Salt: Controls on the Permeability of Fine-Grained Sedimentary Rocks.

The ability to predict the permeability of fine-grained soils, sediments, and sedimentary rocks is a fundamental challenge in the geosciences with potentially transformative implications in subsurface hydrology. In particular, fine-grained sedimentary rocks (shale, mudstone) constitute about two-thirds of the sedimentary rock mass and play important roles in three energy technologies: petroleum geology, geologic carbon sequestration, and radioactive waste management. The problem is a challenging one that requires understanding the properties of complex natural porous media on several length scales. One inherent length scale, referred to hereafter as the mesoscale, is associated with the assemblages of large grains of quartz, feldspar, and carbonates over distances of tens of micrometers. Its importance is highlighted by the existence of a threshold in the core scale mechanical properties and regional scale energy uses of shale formations at a clay content Xclay ≈ 1/3, as predicted by an ideal packing model where a fine-grained clay matrix fills the gaps between the larger grains. A second important length scale, referred to hereafter as the nanoscale, is associated with the aggregation and swelling of clay particles (in particular, smectite clay minerals) over distances of tens of nanometers. Mesoscale phenomena that influence permeability are primarily mechanical and include, for example, the ability of contacts between large grains to prevent the compaction of the clay matrix. Nanoscale phenomena that influence permeability tend to be chemomechanical in nature, because they involve strong impacts of aqueous chemistry on clay swelling. The second length scale remains much less well characterized than the first, because of the inherent challenges associated with the study of strongly coupled nanoscale phenomena. Advanced models of the nanoscale properties of fine-grained media rely predominantly on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, a mean field theory of colloidal interactions that accurately predicts clay swelling in a narrow range of conditions (low salinity, low compaction, Na+ counterion). An important feature of clay swelling that is not predicted by these models is the coexistence, in most conditions of aqueous chemistry and dry bulk density, of two types of pores between parallel smectite particles: mesopores with a pore width of >3 nm that are controlled by long-range interactions (the osmotic swelling regime) and nanopores with a pore width <1 nm that are controlled by short-range interactions (the crystalline swelling regime). Nanogeochemical characterization and simulation techniques, including coarse-grained and all-atom molecular dynamics simulations, hold significant promise for the development of advanced constitutive relations that predict this coexistence and its dependence on aqueous chemistry.

Synthesis and thermoelectric characterization of bulk-type tellurium nanowire/polymer nanocomposites

A simple method to fabricate three-dimensionally (3-D) aligned thermoelectric nanowires attached polymer particle was demonstrated by combination of solution casting of thermoelectric nanostructures (e.g., tellurium nanowires (Te NWs)) on the surface of thermoplastic polymer (e.g., poly(methyl methacrylate (PMMA)) microbeads followed by hot compaction of thermoplastic matrix. The percolation threshold of composite with 3-D assembled Te NWs (i.e., 3.45 vol%) significantly was lower than that of a randomly dispersed Te NWs (i.e., 5.26 vol%), which resulted in an order of magnitude greater thermoelectric figure of merit (ZT of 2.8 × 10−3) compared to randomly dispersed Te NWs in PMMA matrix (ZT of 6.4 × 10−4) at room temperature by enhancing the electrical conductivity without increasing thermal conductivity.

Rheological transitions in progressive melting of rock and their geological constraints from the Fuhu metatexite-diatexite profile in Guangdong Province, SE China

Integration of the published experimental data of partially melted amphibolite, orthogneiss, granite and aplite reveals the existence of three rapid strength drops of the rock-assemblage at melt fraction around 7%, 21% and 41% respectively. The first and the last drops are equivalent to the well-known ‘melt connectivity transition’ (MCT) and ‘solid to liquid transition’ (SLT). The drop at melt fraction around 21% is newly identified and termed as the ‘framework-melting transition’ (FMT). The FMT is defined as the transition from eutectic quartz-feldspars melting to refractory biotite melting. The three rheological transitions are well constrained by the geological data from the Fuhu profile in Guangdong Province, SE China. This profile is a 15m high cliff. Rocks exposed on the profile are zoned as mottled, stripped, narrow-banded and wide-banded migmatites and diatexitic granite from the top of the profile downwards. The leucosome proportions of the zones measured on the outcrops combined with the experimental data of the partially melted rocks have significant implications for understanding the role of rheological transitions during crustal melting.The MCT, which corresponds to the boundary between the mottled and the narrow-banded migmatites, suggests the segregation of melt within the partially melted system along with the compaction of matrix. Thus, the MCT is deemed to be the transition of the partially melted system from matrix-supported (melt stored in pore-space) to framework-supported (melt stored in foliation/bedding-space of protolith).The FMT corresponding to the boundary between the narrow- and the wide-banded migmatites denotes the inception of melting of the solid framework. Mechanically, the FMT can be regarded as the transition of the framework from compaction to fusion, and geochemically, the transition from eutectic melting of quartz-feldspars to that of refractory biotite. The increasing melt due to framework-melting after the FMT is basically limited within the solid framework until the melt fraction exceeding the SLT.The SLT is geologically constrained by the in-situ metatexite-diatexite transition that is also termed as Magma Interface (MI). The SLT (MI) represents the upper limit of a crustal magma layer. Because of the downward increasing temperature and melt fraction, there should be no consecutive layer of felsic rock existed in the space between the SLT (MI) and the mafic lower crust except the isolated rock-blocks within the magma layer.

УЛЬТРАСТРУКТУРНЫЕ ИЗМЕНЕНИЯ КОРТИКОТРОПНЫХ АДЕНОЦИТОВ ГИПОФИЗА ПРИ ДЛИТЕЛЬНОМ ДЕЙСТВИИ КРАСНОГО ШЛАМА

Objective: The study of the features of ultrastructural changes and the character of the reparative processes in corticotropic cells (CC) of adenohypophysis exposure of red sludge. Methods: A study of the ultrastructural organization of the CC of hypophyses of the laboratory rats was carried out on an electron microscope GEM-100CX (Japan). To determine ultrastructural regularities of CC, the morphometric processing of the electron diffraction patterns was carried out on the computer image analyzer IBAS-2000 of OPTON Company (Germany). The concentration of adrenocorticotropic hormone (ACTH) was determined by a «two-step» enzyme immunoassay method for measuring the biologically active molecule of ACTH using the Biometrica test kit (USA). Results: Compared with control animals, in the conditions of exposure of red sludge in 14-day-old rats in the CC of the adenohypophysis, the nuclei indicate an increase in chromatin area, and in the cytoplasm - the amounts of the mitochondrion, secretory granules and its activity. However, in individual CCs, hyperchromium, corrugation and oedema of the nuclei are observed, in the cytoplasm - the vacuolization of the endoplasmic reticulum with partial destruction of its membranes and the formation of cavities, as well as compaction of the mitochondrial matrix. In 45-day-old animals, a reduction amount of chromatin is observed in the nuclei, and mitochondrion and secretory granules in the cytoplasm. In the ultrastructural organization of the majority of CC, the expressed dystrophic and destructive changes are revealed. On the 180th day of the action of red sludge with the simultaneous decrease in the morphometric indices of the CC and increasing in cells the evidence of dystrophic changes, the signs of regeneration have emerged (scale up the size and amount of the elements of the Golgi complex, the granular endoplasmic reticulum, young forms of mitochondrion, free ribosomes and polyribosomes). Conclusion: Reliably in the experiment the influence of red sludge on the ultrastructural organization of CC in the entryway part of hypophysis the temporal dependence effectiveness of adaptive reactions are placed. Maximum tension of mechanisms of adaptation was mentioned in the early period of exposure of red sludge. The inconsistency of adapt-accommodative mechanisms on the 45th day of the experiment was probably connected with the depletion of compensatory mechanisms. The regenerative-compensatory changes in CC in distant deadlines of the experiment proposes the possibility of adaptive regeneration in the time span. Keywords: Adenohypophysis, corticotropic cells, ultrastructure, red sludge.