Fundamental studies of carbon capture using CaO-based materials

Detailed understanding of the mechanisms of fast stage CaO carbonation was given.

Cужение линии поглощения легких атомов щелочных металлов в атмосфере тяжелых инертных газов при росте интенсивности излучения

The effect of narrowing of the absorption line of light alkali metal ^7Li and ^23Na atoms present in an atmosphere of heavy inert gas (xenon) with an increase in the external radiation intensity has been investigated. For ^7Li atoms at temperature T = 300 K and buffer gas (Xe) pressure $${{p}_{{{\text{Xe}}}}} = 0.002$$ Torr, the linewidth at half maximum decreases by a factor of 1.20 with an increase in the radiation intensity from 1 µW/cm^2 to 2.5 mW/cm^2. For ^23Na atoms at T = 600 K and $${{p}_{{{\text{Xe}}}}} = 0.01$$ Torr, the linewidth at half maximum decreases by a factor of 1.29 with an increase in the radiation intensity from 1 µW/cm^2 to 6 mW/cm^2. The effect of field narrowing of the absorption line is due to the following factors. First, the collisional relaxation of the velocities of light resonance particles in an atmosphere of heavy buffer particles is divided into two stages with significantly different durations: relaxation in the velocity direction (fast stage) and relaxation in the velocity magnitude (slow stage). Second, there are no collisional transitions between hyperfine components of the ground state.

Mechanical Impedance Matching Using a Magnetic Linear Gear

As part of the Fp7 Clean Sky Project, a linear magnetic gear prototype, called Z-transmitter, for aerospace application was designed, built, and tested. It demonstrates a maximum force capacity of 4700 N at 25°C and 4500 N at 90°C. Force ratio between slow and fast stages remains constant and equal to the design value: 7.0. The behavior of the real Z-transmitter as a mechanical impedance matching device when any stiffness is attached to the fast stage including the limit cases of a blocked fast stage or a free to move fast stage is experimentally explored. Although the real Z-transmitter deviates from the ideal, frictionless and massless, device, it still provides an impedance matching effect large enough to potentially become an extremely useful technology for vibration control when combined with other elements such as dampers, springs, or active elements.

Activation of persulfate/copper by hydroxylamine via accelerating the cupric/cuprous redox couple

Cuprous copper [Cu(I)] reacts with sodium persulfate (PDS) to generate sulfate radical SO4−•, but it has been seldom investigated owing to its instability and difficulty in dissolving it. This study proposes a new method to regenerate Cu(I) from cupric copper [Cu(II)] by addition of hydroxylamine (HA) to induce the continuous production of radicals through active PDS, and investigates the resulting enhanced methyl orange (MO) degradation efficiency and mechanism in the new system. HA accelerated the degradation of MO markedly in the pH range from 6.0 to 8.0 in the HA/Cu(II)/PDS process. Both SO4−• and hydroxyl radicals (•OH) were considered as the primary reactive radicals in the process. The MO degradation in the HA/Cu(II)/PDS process can be divided into three stages: the fast stage, the transitory stage, and the low stage. MO degradation was enhanced with increased dosage of PDS. Although high dosage of HA could accelerate the transformation of the Cu(II)/Cu(I) cycle to produce more reactive radicals, excess HA can quench the reactive radicals. This study indicates that through a copper-redox cycling mechanism by HA, the production of SO4−• and •OH can be strongly enhanced, and the effective pH range can be expanded to neutral conditions.

A novel approach using a fouling index to evaluate NOM fouling behavior in a low pressure ultrafiltration process

A fouling index (FI) was introduced as a novel approach to investigate natural organic matter (NOM) fouling behavior in a low pressure membrane ultrafiltration process. Humic acid (HA), bovine serum albumin (BSA) and sodium alginate (SA), were used in the experiments. According to FI values, fouling was caused by NOM in two steps: a fast fouling process followed by a slow one. FI of the fast stage (FIF) was much greater than that of the slow one (FIS), showing the initial interaction would play a significant role in the fouling process over a short time. The results of mass balance suggested that a small fraction of DOC was responsible for membrane fouling caused by adsorption. Furthermore, both hydrophobic interaction and electrostatic interaction between NOM and the membrane determined the fouling behavior. Only a portion of foulants was removed after hydraulic washing. The sequence of NOM causing irreversible fouling was BSA > HA > SA, and the sequence of irreversible fouling after alkaline cleaning was SA > BSA > HA. The variations of FI values were consistent with the results of mass balances and flux recovery, which confirmed the FI was a simple and effective tool to describe the membrane fouling process.

Preparation and Luminescence Properties of Rare Earth Magnesium Strontium Silicate Luminescent Fiber

The polypropylene luminescent fiber containing Sr2MgSi2O7: Eu2+, Dy3+ phosphors was prepared by melt-spinning method. Crystal phase structure, spectral features and afterglow properties of the luminescent fiber were tested and analyzed. The results show that the fiber has independent superposition phase features of both Sr2MgSi2O7: Eu2+, Dy3+ and polypropylene; the range of its excitation light wavelength locates among 250~450 nm; it can emit blue light of 460 nm wavelength; its initial luminescent intensity is more than 600 mcd/m2, and afterglow time lasts 7 h; the process of afterglow decay consists of fast stage and slow stage.

The Nature of Lifetime-Degrading Boron-Oxygen Centres Revealed by Comparison of P-Type and N-Type Silicon

Illumination-induced degradation of minority carrier lifetime was studied in n-type Czochralski silicon co-doped with phosphorus and boron. The recombination centre that emerges is found to be identical to the fast-stage centre (FRC) known for p-Si where it is produced at a rate proportional to the squared hole concentration, p2. Since holes in n-Si are excess carriers of a relatively low concentration, the time scale of FRC generation in n-Si is increased by several orders of magnitude. The generation kinetics is non-linear, due to the dependence of p on the concentration of FRC and this non-linearity is well reproduced by simulations. The injection level dependence of the lifetime shows that FRC exists in 3 charge states (-1, 0, +1) possessing 2 energy levels. The recombination is controlled by both levels. The proper identification of FRC is a BsO2 complex of a substitutional boron and an oxygen dimer. The nature of the major lifetime-degrading centre in n-Si is thus different from that in p-Si - where the dominant one (a slow-stage centre, SRC) was found to be BiO2 – a complex involving an interstitial boron.

Alzheimer's disease: rapid and slow progression

The variability in the progression of Alzheimer's disease (AD) across patients has made identification of disease-delaying treatments difficult. Quantitative analysis of this variability has important implications in understanding the pathophysiology of AD and identifying disease-delaying treatments. The functional assessment staging (FAST) procedure characterizes seven stages in the course of AD from normal ageing to severe dementia. The present study applied statistical methods to analyse FAST stage durations from a dataset of 648 AD patients. These methods uncovered two distinct types of disease progression, characterized by different mean progression rates. We identified two separate distributions of FAST stage progression times differing by up to 2 years in mean duration within each stage. These results further indicate that if a patient progresses rapidly through a given FAST stage, then their further progression is also likely to be rapid. These findings support the hypothesis that progression of AD can occur via two different pathophysiological mechanisms that lead to distinct average rates of decline.