Advanced diffuse reflectance spectroscopy for studies of photochromic/photoactive solids.

The present article reports novel opportunities of diffuse reflectance (DR) spectroscopy extended through the use of a cryostat accessory for UV-vis-NIR spectrophotometers to investigate temperature dependences of DR spectra at the fundamental absorption edge of semiconductors at T = 90-600 K. Examined are rutile TiO2, a photochromic rutile TiO2 with strong absorption in the visible region, and the halide double perovskite Cs2AgBiBr6 that exhibited two optical band-to-band transitions in low-temperature DR spectra. Also reported are DR spectral and kinetics measurements of the separation of photogenerated charge carriers in various trap sites, their thermostimulated detrapping and their recombination in two different photochromic materials. The similarity between absorption and temperature-programmed annealing (TPA) spectra induced in the UV and Vis regions yielded physical evidence of the photo-formation of charge carriers upon Vis-light excitation of intrinsic defects (F-type centers) in yellow rutile TiO2. High-temperature oxidative/reductive treatments of samples, together with spectral and kinetics measurements were performed in situ with the accessory. Results led to assigning color centers in yellow TiO2 to Ti3+ centers as deep electron traps, and to the establishment of several types of Ti3+-based color centers that include extra-negatively charged Ti δ+ centers (3 > δ > 2). Photochromic occurrences are also elucidated in the Bi-doped perovskite CsPbBr3 under illumination in the region of intrinsic absorption and annealing of photoinduced absorption at T = 200-400 K. These phenomena are described in terms of the photogeneration of charge carriers followed by their trapping, which yielded Bi-related electron color centers responsible for the photoinduced absorption and for the thermostimulated detrapping of photoholes that ultimately recombine with the trapped electrons. The establishment of photochromism in the perovskites may lead to a further understanding of photoinduced and dark reversible phenomena in halide perovskites and halide perovskite-based solar cells.

Structural features of hydroxyapatite and carbonated apatite formed under the influence of ultrasound and microwave radiation and their effect on the bioactivity of the nanomaterials.

The samples of hydroxyapatite and carbonate substituted hydroxyapatite (CHA) were obtained under the influence of physical factors, namely ultrasound (US) and microwave (MW) radiations. The results of Fourier transform infrared spectroscopy and X-ray diffraction analysis have proved the formation of the calcium deficient hydroxyapatite and B-type CHA with the Ca/P ratio in the ranges 1.62-1.87. In vitro studies have showed the increased bioactivity of the samples, synthesized under the influence of physical factors as compared to the standard ones. The samples of both groups, synthesized under the influence of 600 W MW, have shown the greatest stability in biological environment. In vivo tests confirm that obtained under US and MW radiations hydroxyapatite-based biomaterials are biocompatible, non-toxic and exhibit osteoconductive properties. The usage of US and MW radiations can significantly shorten the time (up to 5-20 min) of obtaining of calcium deficient hydroxyapatite and B-type CHA in nanopowder form, close in structure and composition to the biological hydroxyapatite.

In situ study of photo- and thermo-induced color centers in photochromic rutile TiO2 in the temperature range 90-720 K.

This article reports an in situ UV-Vis-NIR diffuse reflectance (DR) spectroscopic and kinetic study of the photoformation and thermal annealing of light absorbing electronic point defects (color centers) in photochromic TiO2 in the temperature range 90-720 K using a simple laboratory-made cryostat-type accessory (for a Cary 5000 spectrophotometer equipped with an integrating sphere). The accessory also allowed for UV-Vis-NIR DR studies to be undertaken either in vacuum or in an oxygen atmosphere at significantly high temperatures (to 720 K) to assess dark chemical events occurring in photochromic titania with the participation of color centers. The DR spectral and kinetic measurements provided the opportunity to examine the separation of photoinduced charge carriers at traps and thermally stimulated carrier detrapping and recombination, as well as the response of color centers to oxidative/reductive treatments of photochromic TiO2. Kinetic results also demonstrate the applicability of the fabricated DR accessory as a high-temperature reaction cell in the systematic study of the principal regularities in the formation and destruction of color centers in titania at various temperatures and gaseous atmospheres.

Controllability of brushite structural parameters using an applied magnetic field.

The paper studies the influence of low intensity static magnetic field on brushite structural and microstructural parameters using the X-ray diffraction and the transmission electron microscopy. This effect was shown to have various influences on DCPD (Dicalcium Phosphate Dihydrate) structure depending on a magnetic field configuration or time of synthesis, which allows achieving controllability of the main properties of an obtained material. The influence of the magnetic field leads mostly to the decrease of crystallite sizes with no impact on the crystal lattice parameters. In (0 2 0) and (1 5 0) planes the growth of crystallite sizes is observed after 2 and 3 days of crystallization, respectively. The analysis of different contributions to peak broadening in [0 b 0] direction showed a similar trend for the crystallite sizes with the lower lattice microstrains after 2 days of synthesis. The effect similar to the preferred orientation was observed and classified with the Harris method.

Rare case of pathological biomineralization of eye tissue.

The authors have described the case of pathological biomineralization of ocular posterior chamber. Histological examination of affected eye shells revealed inflammation, oedema, dyscirculatory violations, and signs of dystrophic calcification. Structural-phase and chemical analyses of calcification have revealed that the biomineral consists of hydroxyapatite with relatively small crystallite size and defective crystal lattice. In the described case the formation of pathological biomineral in the vision organ was initiated by penetrating wound. Eye injury might have caused a hemophthalmus and chronic inflammatory reaction in the shells, these processes eventually led to the organ subatrophy and to the development of dystrophic and necrobiotic changes in the tissues. Pathological biomineralization in the affected organ developed as a type of dystrophic calcification.Key words: eye, pathological biomineralization, hydroxyapatite.

Silver-doped hydroxyapatite coatings formed on Ti-6Al-4V substrates and their characterization.

Coatings with antibacterial components for medical implants are recommended to reduce the risk of bacterial infections. Therefore hydroxyapatite (HA) coatings with addition of chitosan (CS) and silver (Ag) are proposed in this work in an attempt to resolve this problem. Ti-6Al-4V substrates were modified by a chitosan film to study the influence of surface modification on the formation of the HA-Ag and HA-CS-Ag coatings. Using a thermal substrate method, HA and HA-CS coatings doped with Ag(+) were prepared at low substrate temperatures (90°C). Coated surfaces were examined using X-ray diffraction and scanning electron microscopy. The amount of silver in the deposited coatings was analyzed by atomic absorption spectroscopy. From this study it is concluded that the substrate surface modified by a chitosan film promotes the coating formation and increases the antibacterial activity of produced coatings against a strain of Escherichia coli. The adhesion of E. coli (ATCC 25922) to sheep erythrocytes was decreased by 14% as compared with the reference samples without Ag. It could be explained by the inhibition of bacterial adhesins by Ag(+) ions released. The combined action of silver ions and chitosan resulted in a 21% decrease in adhesive index.

Incidence of tuberculosis and associations with indicators of alcohol consumption in three regions of northwest Russia in 1975-2009: a time-series analysis.

BACKGROUND: Alcohol has several social consequences that are associated with increased risk of tuberculosis. However, there have been no studies assessing the links between tuberculosis and alcohol consumption in northwest Russia. The aim of this study was to assess associations between the incidence of tuberculosis and indicators of alcohol consumption in three regions of northwest Russia. METHODS: The study was performed in Arkhangelsk, Murmansk and Vologda regions using the data from 1975 to 2009. Deaths from alcohol poisoning and the incidence of alcohol psychoses were used as indicators of alcohol consumption. Associations between the incidence of tuberculosis and the above mentioned indicators were studied using time-series analysis. RESULTS: We identified significant positive associations between the incidence of tuberculosis and the incidence of alcohol psychoses in the same year in Arkhangelsk region (ß = 0.24, 95% CI: 0.10-0.37) and in Vologda region (ß = 0.18, 95% CI: 0.10-0.25), but not in Murmansk region. CONCLUSIONS: We found an association between the incidence of alcohol psychoses and the incidence of tuberculosis in the same year in Arkhangelsk and Vologda regions suggesting an indirect link between excessive levels of alcohol consumption and the incidence of tuberculosis in Russia.

On the way to the creation of next generation photoactive materials.

INTRODUCTION: Transition from first- to second-generation photocatalysts has followed the notion that greater absorption of light in the visible region would yield greater spectral sensitivity and greater photoactivity. Though a promising strategy, in practice, it did not meet expectation because of various side issues, which in many cases has led to loss of photoactivity and chemical reactivity. This article examines some earlier notions that arose from applications of different metal oxides (e.g., TiO(2), ZnO, MgO among others) that made these oxides good photocatalysts in many processes. DISCUSSION: Phenomena that proved relevant in developing next generation photoactive materials are considered: the dependence of the activity of photocatalysts on the band gap energy, the spectral variations of the activity of photoactive materials, and the spectral variations of selectivity of photoactive materials. The tendency to decrease the energy of actinic photons through doping in forming second-generation photocatalysts is completely opposite the fundamental observation in first-generation photocatalysts whereby the activity increased with increasing band gap energy. Extension of spectral sensitivity of second-generation photoactive materials also caused a decrease of their photoactivity; hence, some notions are reconsidered to produce next(third) generation photoactive materials. The article proposes the following concepts to develop next generation photocatalysts: (1) multi(two)-photon excitation of photoactive materials with lower energy photons to achieve the same excited state as with higher energy photons, (2) utilization of heterojunctions to drive electronic processes in the desired direction, and (3) selective photoexcitation of localized electronic states to gain better selectivity.

On the genesis of heterogeneous photocatalysis: a brief historical perspective in the period 1910 to the mid-1980s.

The concept Photocatalysis and, of greater import here, Heterogeneous Photocatalysis were first introduced in the second decade (1910-1920) of the 20th century according to the CAPLUS and MEDLINE databases (SciFinder). This review reports a brief historical perspective on the origins of the two concepts, whether implied or explicitly stated, in some detail up to about the mid-1980s when heterogeneous photocatalysis witnessed the beginning of an exponential growth, with particular emphasis on the use of nanosized TiO(2) particles in powdered form as the (so-called) photocatalyst of choice in environmental applications because of its inherent properties of abundance and chemical stability in acidic and alkaline aqueous media (in the dark), in contrast to ZnO that had been the metal oxide of choice in the early days. The early workers in this area often used the term photosensitization rather than the current popular term photocatalysis, used since the early 1980s. The term Photocatalysis appeared in the literature as early as 1910 in a book by Plotnikow (Russia) and a few years later it was introduced in France by Landau. The review also reports on contributions during the early years by Terenin at the University of St. Petersburg (previously Leningrad, Soviet Union), and in the decade spanning 1975-1985 contributions by Bard's group at the University of Texas at Austin (USA) as well as those of other groups. Some activities into the conversion of light energy to chemical fuels (e.g. H(2)) during the 1975-1985 decade are also considered.

[Antibodies to Brucella in caspian seals]. / Antitela k brutsellam u kaspiiskikh tiulenei.

As the result of the study of Caspian seals, the presence of antibodies to Brucella was detected in the blood serum of these animals. The annual dynamics of the proportion of seropositive animals was noted. These data indicate the possibility of the circulation of the infective agent of brucellosis in the population of Caspian seals.

[Adaptation to hyperthermia and changes in peripheral blood leukocytes in humans]. / Adaptatsiia cheloveka k gipertermii i izmeneniia v leikotsitakh perifericheskoi krovi.

Heating humans up to rectal temperature 39.0-39.5 degrees C induces a heat stress and a physiological adaptation. Blood cells were found to produce nitric oxide under these conditions, neutrophiles playing a major role in the process. In our opinion, the HSC 70 takes part in the process of the long cell adaptation augmenting the cells' functional activity. Hyperthermia leads to a massive temporal HSP 72 expression in the blood mononuclears. This expression seems to be due to alterations in the cellular proteins and to oxidative stress.

[Changes in central and cerebral hemodynamics in patients with hypertension after a single-dose administration of corinfar]. / Izmenenie tsentral'noi i tserebral'noi gemodinamiki u bol'nykh gipertonicheskoi bolezn'iu pri odnokratnom prieme korinfara.

The influence of a single corinfar (10 mg) administration on the central and cerebral hemodynamics was studied in 35 patients with I-II stage essential hypertension. Reduction of the arterial pressure following corinfar administration was not attended by deterioration of cerebral blood flow; in most cases there was an increase in pulse blood filling of the cerebral vessels.

[Ultrasonic tomography in assessing the efficacy of the combined treatment of fibrosarcoma]. / Ul'trazvukovaia tomografiia v otsenke éffektivnosti kompleksnogo lecheniia fibrosarkom.

Ultrasonic tomography was used in 40 patients with locally-advanced fibrosarcoma of soft tissues who had undergone polychemotherapy or radiation in combination with short-term (5-10 minutes) ultrasound or microwave treatment of physical therapy intensity (1-2 W/cm2) given as a modifier. These procedures were used prior to surgery in 24 cases and as the only treatment--in 16. Ultrasonic tomography was performed before start, in the middle and right after termination of therapy, and before surgery. Addition of short-term ultrasound and microwave treatment was followed by formation of dense fibrous capsule around the tumor which assured a longer (3-5 years) recurrence-free survival. Ultrasonic tomography allows to monitor formation of the capsule and is, therefore, useful for assessing treatment outcome, making prognosis and determining time and extent of surgery.

[Hemosorption in status epilepticus and serial epileptic seizures]. / Gemosorbtsiia pri épilepticheskom statuse i seriinykh épilepticheskikh pripadkakh.

Hemosorption was performed in 8 patients with a resistant status epilepticus and serial epileptic attacks; arrest of the attacks correlated with significantly faster and stabler normalization of the circulating levels of immune complexes and of the phagocytic activity of neutrophils as compared to the same parameters in patients receiving a course of conventional anticonvulsive and dehydration therapy without hemosorption. The data obtained point to the advisability of the inclusion of hemosorption into a multiple modality treatment of patients with a persistent grand mal status and serial epileptic attacks. High circulating levels of immune complexes in the blood serum may be considered as indication for hemosorption.

[Anti-aggregation action of hypochlorite on the thrombocytes]. / Protivoagregatsionnoe deistvie gipokhlorita na trombotsity.

Sodium hypochlorite at concentrations higher than 1 mM suppresses ADP-dependent aggregation of blood platelets. The effect was associated with the process of cell modification. Blood platelet aggregation may be depressed partially by ADP destruction. Products of ADP-sodium hypochlorite interaction may lead to the induction of blood platelet aggregation, which is not so intensive than the ADP-induced one.