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Active apolar doping determines routes to colloidal clusters and gels
No full textCollections of interacting active particles, self-propelling or not, have shown remarkable phenomena including the emergence of dynamic patterns across different length scales, from animal groups to vibrated grains, microtubules, bacteria, and chemicalor field-driven colloids. Burgeoning experimental and simulation activities are now exploring the possibility of realizing solid and stable structures from passive elements that are assembled by a few active dopants. Here we show that such an elusive task may be accomplished by using a small amount of apolar dopants, namely synthetic active but not self-propelling units. We use blue light to rapidly assemble 2D colloidal clusters and gels via nonequilibrium diffusiophoresis, where microscopic hematite dockers form long-living interstitial bonds that strongly glue passive silica microspheres. By varying the relative fraction of doping, we uncover a rich phase diagram including ordered and disordered clusters, space-filling gels, and bicontinuous structures formed by filamentary dockers percolating through a solid network of silica spheres. We characterize the slow relaxation and dynamic arrest of the different phases via correlation and scattering functions. Our findings provide a pathway toward the rapid engineering of mesoscopic gels and clusters via active colloidal doping.S
Cold Atmospheric Plasma Inactivation of Microbial Spores Compared on Reference Surfaces and Powder Particles
No full textHeat-resistant spores on a dry, heat- and water-sensitive food matrix are difficult to inactivate. Radioactive or X-ray exposure is allowed and accepted only for some selected commodities. Non-thermal atmospheric pressure plasma treatments could offer an efficient, fast, and chemical-free solution. The effectiveness of direct contact cold atmospheric plasma (CAP) generated by a dielectric barrier discharge (DBD) device and air as process gas was evaluated against spores of Bacillus spp., Geobacillus spp., and Penicillium spp. A maximum of 3 log(10) cycles of inactivation was achieved for B. coagulans spores exposed for only 10 s at low surface energy of 0.18 W/cm(2) determined directly at the electrodes. This corresponds to an initial decimal reduction time of D-1 = 0.1 min. Spores of B. subtilis are the most resistant amongst the studied strains (D-1 = 1.4 min). The determining parameter in the modeling of the inactivation curve is surface energy. Non-porous, native starch granules or shells from diatoms, a highly porous material, were also contaminated with spores and treated by DBD CAP. The inactivation level was significantly reduced by the presence of powders. Considering plasma diagnostics, it can be concluded that the spore shell is the primary and main target for a plasma-induced inactivation. The inactivation affect scales with surface energy and can be controlled directly via process time and/or discharge power.SP
Self-assembling biomaterials
No full textA new class of molecules for the preparation of self-assembling biomaterials were synthesized. These molecules consist of a cholesteryl-moiety attached via an oligo(ethylene oxide) or oligo(L-lactic acid) segment to a biologically relevant headgroup. The oligomers were characterized using SAXS, DSC and optical microscopy.LPCited By (since 1996): 2Export Date: 25 September 2007Source: ScopusCODEN: ACPP
On the complexity of nonrecursive XQuery and functional query languages on complex values
No full textDATAJournal version of PODS 2005 paper
Direct evidence for Vogel-Fulcher freezing in relaxor ferroelectrics
No full textDirect evidence for freezing in two relaxer ferroelectrics, PbMg1/3Nb2/3O3 and PbSc1/2Ta1/2O3, at a certain temperature T-f not equal 0K was obtained from the temperature dependence of the maximum relaxation time, tau(max), It was shown that tau(max)(T) follows the Vogel-Fulcher (VF) law, and tends toward infinity as temperature approaches T-f. The freezing temperature T-f derived from tau(max)(T) coincides with the value of T-f obtained from the fit of frequency, omega, dependence of the temperature, T-max, of the dielectric permittivity maximum to the same VF law. Thus, this result solves the controversy that the VF law for omega(T-max) may not correspond to the freezing of the spectrum. (C) 1998 American Institute of Physics.LCGlazounov, AE Penn State Univ, Mat Res Lab, University Pk, PA 16802 USA Ecole Polytech Fed Lausanne, Lab Ceram, CH-1015 Lausanne, Switzerland109CJCited References Count:1
Analysis of familial risk for prostate, colon and female breast cancer in Sweden
No full textUsing the Swedish Familial Cancer Database, organized and studied by the Hemminki group since 1997, the hypotheses that breast, prostate and colorectal cancers were affected by familial risks in Sweden (1958-2008) are tested. The null hypotheses were rejected for the three cancer types up to the age interval 70-74 yrs for which probative data are available. Familial risks, represented as age-specific mortality rate ratios, are found to be age invariant: 1.9±0.3 (95% CI) for sons or daughters ages 45 to 74 of parents dying of colorectal cancer, 2.0 ± 0.2 for sons ages 50 to 74 of fathers dying of prostate cancer. The ratio of the risks for daughters of mothers dying of breast cancer ages 35 to 74, suggests a different behavior between pre-menopause and post-menopause ages. Can be seen as constant at 2.3± 0.3 for all observed age groups. The data could also be interpreted as showing a different behavior between the ages before and after menopause. The ratio could be decreasing linearly before menopause and be constant after menopause. One potential risk parameter is eliminated as familial because this parameter is identical for the general and familial populations: growth rate of preneoplastic lesions. Initiation or promotion oncomutation rates in stem cells could account for the familial risks in accord with wide variations of mutation rates observed in developing colon and lungs. Population parameters such as the fraction of persons in whom initiated stem cells would continue to grow after maturity could also have caused the observed familial risks, with oncomutation rates. For familial colorectal cancer, the two population parameters considered are of little effect, permitting the conclusion that familial colorectal cancer risk lies solely in oncomutation rates. Studies of immigrants have demonstrated that fetal/juvenile environmental factors are major determinants of organ-specific adult cancer risk. From these considerations emerges the hypothesis that the prime determinants of colorectal and other cancer risks lie in the fetal/juvenile oncomutation rates. This hypothesis may be tested directly by measuring and comparing somatic mutations at defined genetic loci (a.) in parents and their adult children (b.) among all adults with and without cancers in a specified organ.SSVLaboratory of Applied statistics, EPFL. - Carried out in the laboratory of Epidemiology at Massachusetts Institute of Technology, under the supervision of William G. Thill
