Growth Kinetics of Vitamin C Crystals in a Batch L(+)-Ascorbic Acid – Methanol – Ethanol – Water System: Size Independent Growth Model Approach

The experimental data concerning growth kinetics of vitamin C (L(+)-ascorbic acid, LAA) crystals in a seeded and cooling batch mass crystallization process realized in a four–compound: L(+)-ascorbic acid–methanol–ethanol–water system are reported. Influences of initial composition of solution and its linear cooling rate on “average, effective” values of crystal linear growth rate were examined. Small divergences between LAA crystal size distributions (CSDs) data from granulometric analysis and Coulter counter were interpreted theoretically and discussed. Linear growth rates of crystals in a batch crystallizer were acquired with a proposed by Nývlt indirect method, based on the analysis of population density n(L) data in a MSMPR (mixed suspension mixed product removal) crystallizer. Size–independent growth (SIG) kinetics was assumed. It can be concluded, that the largest and the most uniform particles of purified, crystalline vitamin C correspond to higher initial concentration of L(+)-ascorbic acid in a solution and lower cooling rate applied

Properties of neutron doped multicrystalline silicon for solar cells

The technology of neutron transmutation doping of silicon wafers in MARIA nuclear research reactor is described. The studies of the radiation defects performed with positron annihilation confirmed that divacancies dominate in the irradiated material. Thermal treatment of irradiated silicon at 700-1000°C produces void - phosphorus complexes and void aggregates. The resistivity of the samples produced by neutron transmutation doping was found to be uniform within 2.5% limits. The severe reduction of the minority carrier lifetime in irradiated samples was confirmed

Quaternary climate modulation of Pb isotopes in the deep Indian Ocean linked to the Himalayan chemical weathering

We use reductive sediment leaching to extract lead (Pb) from the authigenic fraction of marine sediments and reconstruct the Pb isotope evolution of the deep central Indian Ocean over the past 250 thousand years at ∼3 kyr resolution. Temporal variations define a binary mixing line that is consistent with data from ferromanganese nodules and which records mixing between two well-defined endmembers through time. The unradiogenic endmember appears to represent a widely-distributed Pb source, from mid-ocean ridges or possibly volcanic aerosols, while the radiogenic endmember coincides with the composition of Ganges–Brahmaputra river sediments that are indicative of the Himalayan weathering inputs. Glacial–interglacial Pb isotope variations are striking and can be explained by an enhancement of Himalayan contributions by two to three times during interglacial periods, indicating that climate modulates the supply of dissolved elements to the ocean. While these changes could accurately record variations in the continental chemical weathering flux in response to warmer and wetter conditions during interglacials, the relative proportions of Pb derived from the Ganges and Brahmaputra appear to have been constant through time. This observation may point towards particulate-dissolved interactions in the estuary or pro-delta as a buffer of short timescale variability in the composition (and potentially flux) of the fluvial inputs. In addition, the changes are recorded at 3800 m water depth, and with the lack of deep water formation in the Bay of Bengal, a mechanism to transfer such a signature into the deep ocean could either be reversible scavenging of dissolved Pb inputs and/or boundary exchange on the deep sea fan. Unless the mechanism transferring the Pb isotope signature into the deep ocean was itself highly sensitive to global climate cycles, and with the absence of a precessional signal in our Pb isotope data, we suggest that the Indian climate and its influence on basin-scale chemical weathering were strongly modulated by glacial versus interglacial boundary conditions

Growth Kinetics of Vitamin C Crystals in a Batch L(+)-Ascorbic Acid – Methanol – Ethanol – Water System: Size Independent Growth Model Approach

The experimental data concerning growth kinetics of vitamin C (L(+)-ascorbic acid, LAA) crystals in a seeded and cooling batch mass crystallization process realized in a four–compound: L(+)-ascorbic acid–methanol–ethanol–water system are reported. Influences of initial composition of solution and its linear cooling rate on “average, effective” values of crystal linear growth rate were examined. Small divergences between LAA crystal size distributions (CSDs) data from granulometric analysis and Coulter counter were interpreted theoretically and discussed. Linear growth rates of crystals in a batch crystallizer were acquired with a proposed by Nývlt indirect method, based on the analysis of population density n(L) data in a MSMPR (mixed suspension mixed product removal) crystallizer. Size–independent growth (SIG) kinetics was assumed. It can be concluded, that the largest and the most uniform particles of purified, crystalline vitamin C correspond to higher initial concentration of L(+)-ascorbic acid in a solution and lower cooling rate applied

28 Brachyterapia HDR w leczeniu nieoperacyjnego raka przełyku

WstępChorzy zdyskwalifikowani od zabiegu operacyjnego z powodu umiejscowienia oraz zaawansowania klinicznego raka przełyku są grupą o złym rokowaniu. Nieliczni mogą być zakwalifikowani do radykalnej teleterapii, większość chorych jest leczona objawowo. W pracy przedstawiono wstępne wyniki brachyterapii HDR chorych na nieoperacyjnego raka przetyku.Materiał i metodyW okresie od maja 1999 do lutego 2000 poddano brachyterapii HDR w Wielkopolskim Centrum Onkologii 37 chorych na nieoperacyjnego raka przełyku. Wiek chorych sięgał od 42 do 81 lat, średnio 53,1 lat. W brachyterapii HDR stosowano najczęściej dawkę 21,5 Gy na guz w trzech frakcjach, w 5 przypadkach dodatkowo napromieniono śródpiersie dawką 20 Gy w 5 frakcjach. U 5 chorych leczonych radykalnie zastosowano po brachyterapii teleterapię w dawce od 50 do 60 Gy na okolicę przełyku. Oceniono wpływ stosowanego leczenia na uzyskanie remisji miejscowej oraz ustępowanie dysfagii w 1, 3 i 6 miesiącu po zakończeniu leczenia.WynikiŚredni okres obserwacji wynosił 6 miesięcy. Remisję całkowitą ocenianą w 1 miesiącu po zakończeniu leczenia stwierdzono u 4 chorych (10,8%), częściową u 25 chorych (67,6%), brak remisji u 8 chorych (21,6%). Po 3 i 6 miesiącach remisja utrzymywata się u 2/3 chorych pozostających w obserwacji. W grupie chorych leczonych metodą skojarzoną remisję catkowitą stwierdzono u 2 chorych (20%), częściową u 6 chorych (60%). U 4 chorych (10,8%) w trakcie badań kontrolnych wykryto przetokę.WnioskiBrachyterapia HDR wpłynęła na ustępowanie dysfagii u znacznej części chorych na nieoperacyjnego raka przełyku. U niektórych chorych uzyskano całkowitą remisję utrzymującą się dłużej niż pół roku. Tolerancja leczenia była dobra, a odsetki powikłań nie odbiegały od uzyskanych przez innych autorów

An Analysis of the Quantum Penny Flip Game using Geometric Algebra

We analyze the quantum penny flip game using geometric algebra and so determine all possible unitary transformations which enable the player Q to implement a winning strategy. Geometric algebra provides a clear visual picture of the quantum game and its strategies, as well as providing a simple and direct derivation of the winning transformation, which we demonstrate can be parametrized by two angles. For comparison we derive the same general winning strategy by conventional means using density matrices.Comment: 8 Pages, 1 Figure, accepted for publication in the Journal of Physical Society of Japa