Phase formation,structure and properties of light-weight aluminosilicate proppants based on clay-diabase and clay-granite binary mixes

One of the drawbacks of fusible clays is the narrow sintering interval due to a sharp increase in the amount of iron-silicate melt at a temperature of 1000–1100 °C, which hardens in the form of a glass phase upon cooling. This leads to a relatively low mechanical strength of the calcined samples and causes the danger of melting the granular material surface from such clays during the firing process. To increase the strength of samples of fusible clays, the influence of diabase and granitoid rocks was considered. It was found that the strengthening effect of diabase and granitoid rock additives in an amount of 20–50% in a mixture with fusible clay is due to an increase of total content of the crystalline phase (mullite, cristobalite and residual quartz) from 18–20% in clays without additives to 22–28 % - in mixtures with diabase and to 28–34% - with granitoid additives) at a temperature of 1050–1100 °C. This increase is due to the activation of synthesis processes of secondary mullite and crystallization from alkali-rich feldspar melt of amorphous silica, released from the structure of clay minerals. The established influence of the igneous rocks used made it possible to develop compositions and propose process flow sheet for producing aluminosilicate proppants based on fusible clays. The use of granitoid and diabase rocks in an amount of 20–70% with fusible clays produces lightweight aluminosilicate proppants with bulk density of 1.40–1.46 g/cm³ at temperature range of 1050–1100 °C, which can endure destructive pressures up to 34.5–52 MPa.     

Optical spectroscopic and electrochemical characterization of oxide films on a ferritic stainless steel

Colored oxide films that form on ferritic stainless steel in a high-temperature, oxidizing environment and correspond to different chemical compositions can cause a deterioration of pitting resistance and corrosion performance. Herein, optical spectroscopic and electrochemical techniques have been used to reveal the relationship between color, chemical composition, and corrosion resistance of oxide films formed in the temperature range from 400°C to 800°C for 30 min and at 800°C for 10, 20, 30, and 60 min. The substrate with a thin and dense passivation film leads to a low pitting potential but high corrosion resistance. Oxide films of yellowish or brownish color formed below 600°C are mainly iron oxides, which correspond to low corrosion resistance. No passivation characteristics can be observed for polarization curves of oxide films formed at 500°C and 600°C. The color of oxide films varies from blue to dark gray with the increase of oxidation time at 800°C. Corrosion resistance changes with different proportions of Fe₃O₄, Cr₂O₃, and FeCr₂O₄. The gray oxide films formed at 800°C for 30 min exhibit the lowest pitting susceptibility and the highest corrosion resistance.     

Recent developments in modelling of microhardness saturation during SPD processing of metals and alloys

Ultrafine-grained and even nanostructured materials can be fabricated using severe plastic deformation to ultra-high strains in equal-channel angular pressing (ECAP), high-pressure torsion (HPT), machining and their combinations, such as machining of ECAP specimens, HPT of ECAP billets and HPT of machining chips. This report presents recent results of investigations of the microstructures and microtextures of pure copper, nickel and aluminium subjected to different deformation processes to ultimately high imposed strains. A comparison of the microstructure, dislocation density and microhardness developed during combinations of different strain paths is performed. All characteristics were analysed by X-ray, transmission and scanning electron microscopy, and electron backscatter diffraction (EBSD). The influence of different processing routes is discussed in terms of the accumulated strain and microstructure refinement. The saturation in grain refinement is examined with reference to the recovery taking place during ultra-high strain deformation. A phenomenological model based on the Voce equation is applied for fitting parameters based on the experimental data and this is suggested for a prediction of microhardness evolution for pure metals (Ag, Au) and Cu-based (Zn, Al) alloys.     

The effect of multi-walled carbon nanotubes addition on the thermo-oxidative decomposition and flammability of PP/MWCNT nanocomposites

Studies of thermo-oxidative and fire-resistant properties of the polypropylene/multi-walled carbon nanotube composites (PP/MWCNT) prepared by melt intercalation are discussed. The effective kinetic parameters of the PP/MWCNT thermo-oxidative decomposition were computed according to the model-based kinetic analysis. The thermo-oxidative decomposition behavior of PP/MWCNT and stabilizing effect caused by addition of MWCNT has been investigated by means of TGA and EPR spectroscopy. Comparative analysis of the flammability characteristics for PP-clay/MWCNT nanocomposites was provided in order to emphasize the specific behavior of the nanocomposites.     

From embedded sensors to sensorial materials—The road to function scale integration

Ubiquitous computing is about to become part of our everyday lives by integrating hundreds of “invisible” to us computing devices in our environment, so that they can unobtrusively and constantly assist us. This will imply more and smaller “invisible” sensors, homogeneously distributed and at the same time densely packed in host materials, responding to various stimuli and immediately delivering information. In order to reach this aim, the embedded sensors should be integrated within the host material, heading towards sensorial materials. The first step is to omit all parts that are not needed for the sensorial task and to find new solutions for a gentle integration. This is what we call function scale integration. The paper discusses sensor embedding in the human hand as an example of integration in nature, new technological applications and main challenges associated with this approach.     

黑果枸杞籽油的氧化稳定性研究

以黑果枸杞籽油为研究对象,探究黑果枸杞籽油储藏过程中,水、空气、温度、金属离子、光照、抗氧化剂对其过氧化值(POV)的影响。结果表明:黑果枸杞籽油在避光、密封、低温、含有少量水的条件下储藏,其POV增长慢于对照组;添加不同金属离子的黑果枸杞籽油在(100±1)℃储藏132h,POV从高到低依次为FeCl_3 MnSO_4 K_2SO_4 CuSO_4对照组 NaCl MgCl_2 AlCl_3 CaCl_2ZnCl_2,其中添加了FeCl_3、MnSO_4、K_2SO_4、CuSO_4升高了黑果枸杞籽油的POV,而添加MgCl_2、AlCl_3、NaCl、CaCl_2、ZnCl_2降低了黑果枸杞籽油的POV,但降低效果不明显;加入抗氧化剂的黑果枸杞籽油的POV均低于对照组,抗氧化能力依次为TBHQ+BHA TBHQ+VE TBHQ BHA BHA+VE VE。     

Fluorinated Talc Based Ceramic Materials

Glass and Ceramics - A densely sintered ceramic with a protoenstatite crystalline phase was obtained on the basis of fluorinated talc. The influence of BaO and Al2O3 additives on the sintering,...     

Primary intraventricular hemorrhage in adults: clinical features, risk factors, and outcome

BACKGROUND AND PURPOSE: Nontraumatic primary intraventricular hemorrhage in adults is uncommon. The purpose of this study was to identify clinical features, risk factors, and outcome of primary intraventricular hemorrhage in adults. METHODS: We identified computed tomography scans for nontraumatic primary intraventricular hemorrhage performed between 1982 and 1993 at our institutions and reviewed medical records to determine clinical features, risk factors, and outcomes of these patients. RESULTS: Of 14 cases studied, the onset of symptoms was acute in all and the most common symptom was headache (78%), followed by nausea/vomiting (71%), and mental status change (71%). Seizures as well as focal neurologic deficits were uncommon. The associated risk factors were hypertension in 7 cases, aneurysm or arteriovenous malformation in 5, coagulopathy in 1, and fibromuscular dysplasia in 1 case. Five patients died acutely, and all of the survivors returned to functional independence. The patients with lethargy, pupillary and extraocular movement abnormalities, quadriparesis, hydrocephalus, and aneurysmal intraventricular hemorrhage had worse outcomes. CONCLUSION: Patients with nontraumatic primary intraventricular hemorrhage present with sudden onset of diffuse neurologic symptoms. The mortality in early phase is high (36%) and the prognosis for survivors is good. Factors correlating with the outcome are discussed.     

AN OIL MIGRATION AND RE-ENTRAPMENT MODEL FOR THE MARDIN GROUP RESERVOIRS OF SOUTHEAST ANATOLIA

Oil migrates from a source into a reservoir rock and then, inside the reservoir rock, into a trap, and from the trap into a series of traps and reservoir rocks. The movement of oil is continuous and the interchange of oil between several reservoir rocks is totally independent of the source rock after a certain stage of migration. Each migration stage may cause quality changes in the properties of oil. A model is devised to account for oil migration and re-entrapment, and to explain the distribution of different quality oils in time and space. Variations in the API-gravity of oil, formation-water salinity, reservoir temperature and pressure, sulphur-content of oil, initial water content and recoverable oil reserves of oilfields can be important clues for the determination of migration directions and new prospects. These concepts were applied in a petroleum migration study of the Mardin Group (Aptian-Turonian) which is the most important reservoir rock of SE Anatolia.
Quantitative modelling shows that oil migration is directed towards two main uplifts which control the distribution of oilfields in SE Anatolia. Active water movement inside the reservoir rock has resulted in the accumulation of oil inside very young structural traps. Because almost all the fields have tilted oil-water contacts, wildcat locations must be selected with special emphasis on hydrodynamics.