LTA zeolite can be prepared from dry mixes in a vibratory mill with an impact-shear loading conditions. For the synthesis of LTA zeolite, it is necessary to use the anhydrous ingredients (Al
2
Si
2
O
...7
–metakaolin, γ-Al
2
O
3
). The process of synthesis is controlled by X-ray diffraction, IR-spectroscopy, and atomic-force microscopy. The presence of structural water in the initial ingredients (Al
2
Si
2
(OH)
4
–kaolin or Al(OH)
3
) leads to the formation of feldshpatoids (nepheline, sodalite). It was established that the process of mechanical activation requires the synthesis of sodium aluminate of cubic and/or tetragonal crystal systems with a lattice parameters close to those for LTA zeolite. These sodium aluminate acts as a steric template for an “assembly” of the zeolite. The presence of sodium aluminate with some other crystal structure results in the formation of sodalite. There is an optimal time of mechanochemical activation, which is determined by the synthesis of sodium aluminate with cubic or tetragonal crystal structure. A model of the mechanochemical synthesis of LTA zeolite was proposed.
The temperature dependence of the Fano resonance recently discovered in infrared spectra of nanodiamonds synthesized from chloroadamantane at high static pressures is investigated. For the first ...time, marked variations of the resonance parameters are observed. On heating, the shape of the Fano resonance changes considerably; the effect completely disappears above 350°C, but is recovered after cooling to ambient conditions. Such behavior implies that assignment of the Fano effect to the surface transfer doping mechanism is not very plausible for the studied samples. The resonance shape varies due to a strong temperature dependence of the difference between the frequencies of infrared-active “bright” and Raman-active “dark” modes of nanodiamond. The frequency of the Raman dark mode is only weakly temperature-dependent.
The paper presents new data on the isotopic age and chemical composition of volcanic rocks from the Tytyl’veem and Mangazeika basins of western Chukotka superposed on Mesozoides of the ...Verkhoyansk–Chukotka Tectonic Region. The results of SIMS U–Pb zircon dating (121.4 ± 2.8 and 118.0 ± 2.0 Ma) corroborate the Aptian age of the Tytyl’veem Formation. This age, in turn, indicates its formation after closure of the South Anyui ocean (Neocomian), but before origination of the Okhotsk–Chukotka Belt (Albian–Campanian). Post-collisional Aptian igneous rocks are widespread in the northern Verkhoyansk–Chukotka Tectonic Region; the legth of the corresponding igneous province is no less than 1400 km. In geochemical characteristics, the post-collisional volcanic rocks occurring in Western Chukotka are similar with the rocks from Andean-type igneous belts.
New results of thermobarogeochemical studies show that quartz veins in the Drazhnoe deposit were formed under mesozonal conditions at a depth of 3–9 km from heterogeneous carbon dioxide–aqueous ...fluids with a low concentration of brines and high contents of CO
2
, which is typical of ore-forming fluids in orogenic vein gold deposits. Based on the phase composition, three types of fluid inclusions are distinguished: (1) carbon dioxide–aqueous; (2) gaseous, filled with dense carbon dioxide; and (3) a two-phase gas–liquid of aqueous–brine solutions. Na, Mg, and Fe chlorides predominated in the ore-forming fluids. It is assumed that the fluids migrated along the regional Adycha–Taryn shear zone and were uplifted to the Earth’s surface at a supra-lithostatic pressure, which was followed by precipitation of ore elements and the formation of quartz veins during tectonic movements along shear zones.
Fluid inclusions were studied in quartz from economic ores of the Svoboda area, which is one of the main economic areas of the Malmyzh Au–Cu porphyry deposit. The economic Au–Cu mineralization of the ...deposit formed mostly from chloride fluid. The main physicochemical parameters of the ore-forming include a temperature of 250–350°C, a salinity of 0.8–48.0 wt % NaCl equiv., and a pressure of 15–62 MPa. The calculations of the pressure of ore-forming fluid indicate the depth of the formation of ore mineralization in a range of 1.5–2.4 km and a 900 m ascent of the ore-hosted block during ore deposition. Our data can be used during prospecting and exploration works at Au–Cu porphyry deposits.
We generalize, for the first time, published and original data on the gallium concentrations in natural magmatic melts and fluids obtained by studying quenched glasses in volcanic rocks and ...inclusions in minerals. Based on 2688 determinations, gallium concentrations in magmatic melts vary between 0.47 and 495 ppm at average content of 18.0 ppm (+4.2/–3.4). Gallium concentrations in magmatic melts generated in different geodynamic settings show different distribution. Minimum concentrations (on average, 16.0 ppm, +3.6/–2.9) are typical of the island-arc melts, while maximum contents were determined in melts of oceanic islands (on average, 29.1 ppm, +13.4/–9.2) and intracontinental rifts and hot spots (26.5 ppm, +25.4/–13.0). Published and new 339 determinations of gallium concentrations in natural fluids indicate the wider range of their variations as compared to those of melts: from 0.02 to 11260 ppm, at average 1.6 ppm (+10.8–1.4). The possible gallium fractionation in fluid—magmatic systems is discussed.
The effect of ultrasonic treatment on the thermal behavior of the mixtures from metakaolin, sodium hydroxide and alumina designed for LTA zeolites synthesis was studied. X-ray diffraction analysis, ...infrared spectroscopy, scanning electron microscopy and synchronous thermal analysis have been used. It was shown that after evaporation of the suspension, LTA zeolite (24 mass%) is contained in the samples. It was established that the new phase (sodium aluminum silicate) is formed at a calcination temperature of about 600 °C. It was demonstrated that at a calcination temperature over 800 °C, nepheline is synthesized. The reaction of nepheline formation has been described by the topochemical equation of four-dimensional nucleation/nucleus growth according to Avrami/Erofeev. Using the Ozawa–Flynn–Wall analysis for non-isothermal data, the values of the activation energy and the pre-exponential factor have been calculated. It is shown that after the ultrasonic treatment the activation energy of the nepheline synthesis reaction has smaller values than in the sample without pretreatment. These phenomena have been explained by differences between the structural parameters of the particles (dimension of the coherent scattering region, the value of microdeformations).
We studied specific antitumor activity of a liposomal drug based on tetra-3-phenylthiophthalocyanine aluminum hydroxide (lipophthalocyan) intended for photodynamic therapy. The optimal dose and ...protocol for photodynamic therapy with lipophthalocyan were chosen in experiments on mice: single intravenous dose of 6 mg/kg with a 5-h interval between administration and laser exposure and irradiation energy density of 400 J/cm
2
. A wide spectrum antitumor activity of lipophthalocyan was demonstrated
in vivo
for various transplantable mouse tumors (Lewis lung epidermoid carcinoma, S37 sarcoma, and colon adenocarcinoma AKATOL). The results show the possibility of using lipophthalocyan for photodynamic therapy of tumors of surface localization (skin and mucosa tumors).
The possibility of obtaining additional information on the properties of Si–SiO
2
structures from joint analysis of the electroluminescence and cathodoluminescence spectra in the spectral range of ...250–800 nm is shown. It is found that the concentration of luminescent centers responsible for the 2.2-eV band is independent from the final thickness of the oxide layer and the centers are uniformly distributed over the SiO
2
thickness. It is shown that the luminescent centers responsible for the 4.2-eV band are characterized by a nonuniform distribution and form mainly in the outer part of the oxide layer (~30 nm) in amount proportional to the square root of the thermal oxidation time, which makes it possible to relate their formation to diffusion of oxidant components.
Paragenetic associations of tetrahedrite-(Zn) and sphalerite are distinguished in the Teremki gold-ore deposit. The chemical composition of coexisting minerals of this association is determined. The ...Sb/(Sb + As) and Fe/(Fe + Zn) ratios in tetrahedrite-(Zn) vary from 0.66 to 0.97 and from 0.28 to 0.40, respectively. A negative correlation was established between Sb/(Sb + As) and Fe/(Fe + Zn) ratios. Contents of Fe in sphalerite change from 0.88 to 1.43 wt % (1.5–2.5 mol % FeS). Temperature and sulfur fugacity when precipitation of tetrahedrite-(Zn)–paragenesis were estimated: they range from 130 to 280°C and from 10
–13.2
to 10
–8.1
bars, respectively.
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