Monodisperse Latex Reactor (MLR): A materials processing space shuttle mid-deck payload

The monodisperse latex reactor experiment has flown five times on the space shuttle, with three more flights currently planned. The objectives of this project is to manufacture, in the microgravity environment of space, large particle-size monodisperse polystyrene latexes in particle sizes larger and more uniform than can be manufactured on Earth. Historically it has been extremely difficult, if not impossible to manufacture in quantity very high quality monodisperse latexes on Earth in particle sizes much above several micrometers in diameter due to buoyancy and sedimentation problems during the polymerization reaction. However the MLR project has succeeded in manufacturing in microgravity monodisperse latex particles as large as 30 micrometers in diameter with a standard deviation of 1.4 percent. It is expected that 100 micrometer particles will have been produced by the completion of the the three remaining flights. These tiny, highly uniform latex microspheres have become the first material to be commercially marketed that was manufactured in space

Large-size monodisperse latexes as a commercial space product

Proposed spacelab production of large-size (2-40 micron diameter) monodispersed latexes is discussed. Explanations are given for the present lack of monodisperse particles in this size range. The four main topics discussed are: (1) the potential uses of these large particle size latexes, (2) why it is necessary for the particles to have a very narrow size distribution, (3) why large amounts of these monodisperse latexes are needed, and (4) why it is necessary to go to microgravity to prepare these latexes

Process for preparation of large-particle-size monodisperse latexes

Monodisperse latexes having a particle size in the range of 2 to 40 microns are prepared by seeded emulsion polymerization in microgravity. A reaction mixture containing smaller monodisperse latex seed particles, predetermined amounts of monomer, emulsifier, initiator, inhibitor and water is placed in a microgravity environment, and polymerization is initiated by heating. The reaction is allowed to continue until the seed particles grow to a predetermined size, and the resulting enlarged particles are then recovered. A plurality of particle-growing steps can be used to reach larger sizes within the stated range, with enlarge particles from the previous steps being used as seed particles for the succeeding steps. Microgravity enables preparation of particles in the stated size range by avoiding gravity related problems of creaming and settling, and flocculation induced by mechanical shear that have precluded their preparation in a normal gravity environment

The first products made in space: Monodisperse latex particles

The preparation of large particle size 3 to 30 micrometer monodisperse latexes in space confirmed that original rationale unequivocally. The flight polymerizations formed negligible amounts of coagulum as compared to increasing amounts for the ground-based polymerizations. The number of offsize large particles in the flight latexes was smaller than in the ground-based latexes. The particle size distribution broadened and more larger offsize particles were formed when the polymerizations of the partially converted STS-4 latexes were completed on Earth. Polymerization in space also showed other unanticipated advantages. The flight latexes had narrower particle size distributions than the ground-based latexes. The particles of the flight latexes were more perfect spheres than those of the ground-based latexes. The superior uniformity of the flight latexes was confirmed by the National Bureau of Standards acceptance of the 10 micrometer STS-6 latex and the 30 micrometer STS-11 latexes as Standard Reference Materials, the first products made in space for sale on Earth. The polymerization rates in space were the same as those on Earth within experimental error. Further development of the ground-based polymerization recipes gave monodisperse particles as large as 100 micrometer with tolerable levels of coagulum, but their uniformity was significantly poorer than the flight latexes. Careful control of the polymerization parameters gave uniform nonspherical particles: symmetrical and asymmetrical doublets, ellipsoids, egg-shaped, ice cream cone-shaped, and popcorn-shaped particles

Crustal flow around the Eastern Himalayan Syntaxis in western Yunnan, China

Abstract HKT-ISTP 2013 A

Fractional Liouville and BBGKI Equations

We consider the fractional generalizations of Liouville equation. The normalization condition, phase volume, and average values are generalized for fractional case.The interpretation of fractional analog of phase space as a space with fractal dimension and as a space with fractional measure are discussed. The fractional analogs of the Hamiltonian systems are considered as a special class of non-Hamiltonian systems. The fractional generalization of the reduced distribution functions are suggested. The fractional analogs of the BBGKI equations are derived from the fractional Liouville equation.Comment: 20 page

X-linked agammaglobulinemia diagnosed late in life: case report and review of the literature

<p>Abstract</p> <p>Background</p> <p>Common variable immune deficiency (CVID), one of the most common primary immunodeficiency diseases presents in adults, whereas X-linked agammaglobulinemia (XLA), an inherited humoral immunodeficiency, is usually diagnosed early in life after maternal Igs have waned. However, there have been several reports in the world literature in which individuals have either had a delay in onset of symptoms or have been misdiagnosed with CVID and then later found to have mutations in Bruton's tyrosine kinase (BTK) yielding a reclassification as adult-onset variants of XLA. The typical finding of absent B cells should suggest XLA rather than CVID and may be a sensitive test to detect this condition, leading to the more specific test (Btk mutational analysis). Further confirmation may be by mutational analyses.</p> <p>Methods</p> <p>The records of 2 patients were reviewed and appropriate clinical data collected. BTK mutational analysis was carried out to investigate the suspicion of adult-presentation of XLA. A review of the world literature on delayed diagnosis of XLA and mild or "leaky" phenotype was performed.</p> <p>Results</p> <p>2 patients previously diagnosed with CVID associated with virtual absence of CD19⁺B cells were reclassified as having a delayed diagnosis and adult-presentation of XLA. <b>Patient 1</b>, a 64 yr old male with recurrent sinobronchial infections had a low level of serum IgG of 360 mg/dl (normal 736–1900), IgA <27 mg/dl (normal 90–474), and IgM <25 mg/dl (normal 50–415). <b>Patient 2</b>, a 46 yr old male with recurrent sinopulmonary infections had low IgG of 260 mg/dl, low IgA <16 mg/dl, and normal IgM. Mutational analysis of BTK was carried out in both patients and confirmed the diagnosis of XLA</p> <p>Conclusion</p> <p>These two cases represent an unusual adult-presentation of XLA, a humoral immunodeficiency usually diagnosed in childhood and the need to further investigate a suspicion of XLA in adult males with CVID particularly those associated with low to absent CD19⁺B cells. A diagnosis of XLA can have significant implications including family counseling, detecting female carriers, and early intervention and treatment of affected male descendents.</p

Photocurrent in nanostructures with asymmetric antidots

The steady current induced by electromagnetic field in a 2D system with asymmetric scatterers is studied. The scatterers are assumed to be oriented cuts with one diffusive and another specular sides. Besides, the existence of isotropic impurity scatterers is assumed. This simple model simulates the lattice of half-disk which have been studied numerically recently. The model allows the exact solution in the framework of the kinetic equation. The static current response in the second order of electric field is obtained. The photogalvanic tensor contains both responses to linear and circular polarization of electromagnetic field. The model possesses non-analyticity with regards to the rate of impurity scattering.Comment: 9 pages, 6 figure

Big Entropy Fluctuations in Nonequilibrium Steady State: A Simple Model with Gauss Heat Bath

Large entropy fluctuations in a nonequilibrium steady state of classical mechanics were studied in extensive numerical experiments on a simple 2-freedom model with the so-called Gauss time-reversible thermostat. The local fluctuations (on a set of fixed trajectory segments) from the average heat entropy absorbed in thermostat were found to be non-Gaussian. Approximately, the fluctuations can be discribed by a two-Gaussian distribution with a crossover independent of the segment length and the number of trajectories ('particles'). The distribution itself does depend on both, approaching the single standard Gaussian distribution as any of those parameters increases. The global time-dependent fluctuations turned out to be qualitatively different in that they have a strict upper bound much less than the average entropy production. Thus, unlike the equilibrium steady state, the recovery of the initial low entropy becomes impossible, after a sufficiently long time, even in the largest fluctuations. However, preliminary numerical experiments and the theoretical estimates in the special case of the critical dynamics with superdiffusion suggest the existence of infinitely many Poincar\'e recurrences to the initial state and beyond. This is a new interesting phenomenon to be farther studied together with some other open questions. Relation of this particular example of nonequilibrium steady state to a long-standing persistent controversy over statistical 'irreversibility', or the notorious 'time arrow', is also discussed. In conclusion, an unsolved problem of the origin of the causality 'principle' is touched upon.Comment: 21 pages, 7 figure