Methorics of Coagulation Processes. XIII. Systematic Comparison of Coagulation Values for Various Cationson Negative Silver Halogenide Sols*

The results on coagulating effects of the following electrolytes are reported: on negative silver bromide sol: HNO3, LiNO3, NaNO3, KNO3, H2S04, Li2SO4, Na2SO4, K2S04, Mg(NOAl2, Mn(N03)2, Ca(NO3)2,Sr(NO3)2, Ba(NO3)2, MgSO4, MnSO4, CaSO4, Al(NO3)3, Ce(NO3)3, La(NO3)2; on negative silver iodide sol: LiNO3, NaNO3, KNO3,H2SO4, Li2SO4, Na2SO4, K2SO4, Mg(NO3)2, Mn(NO3)2, Ca(NO3)2, Sr(NOa3)2, Ba(NO3)2, MgSO4 , MnSO4, CaSO4, Al(NO3)3, La(NO3)2 and Al2(S04)3; on negative silver chloride sol: KNO3, Mg(N03), Ca(NO3)2, Sr(NO3)2, Ba(NO3)2, MgS04, CaSO4, Al(N03)3, and La(NO3)3 . As shown earlier a linear relationship exists between the crystallographic radii of the counterions of the same valency and the logarithms of the corresponding coagulation values; the characteristic coagulation values obtained when extrapolating the straight lines of the preceding plots to the zero radius were used for testing the validity of expression for quantitative interpretation of the Schulze- Hardy rule. The equations which follow from the theories of Freundlich and Verwey and Overbeek did not fit the experimental observations, while the equations of Whetham and Tefak showed quite a good agreement

Book Reviews

Gmelins Handbuch der anorganischen Chemie: Zirkonium (I. Filipović) Gmelins Handbuch der anorganischen Chemie: Hafnium (I. Filipović) Gmelins Handbuch der anorganischen Chemie: Germanium (I. Filipović) Gmelins Handbuch der anorganischen Chemie: Sauerstoff (I. Filipović) Paul Delahay: Instrumental Analysts (K. F. Schulz) K. A. Stacey: Light-scattering in Physicai Chemistry (J. Kratohvil

Low Energy Properties of the (n,n) Carbon Nanotubes

According to band theory, an ideal undoped (n,n) carbon nanotube is metallic. We show that the electron-electron interaction causes it to become Mott insulating with a spin gap. More interestingly, upon doping it develops superconducting fluctuations.Comment: 5pages, 2eps figures, one reference added, final version, accepted to PR

The Central Velocity Field in NGC 253 : Possible Indication of a Bar

We have investigated whether motion of gas in a bar-like potential can account for the peculiar but systematic velocity field observed in the nuclear region of the starburst galaxy NGC 253. This unusual velocity field with gradients along both major and minor axes was revealed in a high resolution (1.8^{\arcsec}\times 1.0^{\arcsec}) H92$\alpha$ recombination line observation by Anantharamiah and Goss (1996). A simple logarithmic potential is used to model the bar. Assuming that the bulk of the gas flows along closed and non-intersecting x1 (bar) and x2 (anti-bar) orbits of the bar potential, we have computed the expected velocity field and position-velocity diagrams and compared them with the observations. A comparison of the integrated CO intensity maps with the spatial distribution of the x1 and x2 orbits in the model indicates that the nuclear molecular gas in NGC 253 lies mainly on the x2 orbits. We also find that the velocity field observed in the central 100 pc region in the H92$\alpha$ recombination line is well accounted for by the bar model if most of the ionized gas resides in the inner x2 orbits. However, the model is unable to explain the velocity field on a larger scale of $\sim 500$ pc observed using the OVRO interferometer with a resolution of 5^{\arcsec}\times 3^{\arcsec}. The direction of the observed CO velocity field appears twisted compared to the model. We suggest that this perturbation in the velocity field may be due to an accretion event that could have occurred $10^7$ years ago.Comment: 26 latex pages, 7 figures, accepted in Astrophysical Journa

Configurational Entropy and Diffusivity of Supercooled Water

We calculate the configurational entropy S_conf for the SPC/E model of water for state points covering a large region of the (T,rho) plane. We find that (i) the (T,rho) dependence of S_conf correlates with the diffusion constant and (ii) that the line of maxima in S_conf tracks the line of density maxima. Our simulation data indicate that the dynamics are strongly influenced by S_conf even above the mode-coupling temperature T_MCT(rho).Comment: Significant update of reference

Unified analysis of terminal-time control in classical and quantum systems

Many phenomena in physics, chemistry, and biology involve seeking an optimal control to maximize an objective for a classical or quantum system which is open and interacting with its environment. The complexity of finding an optimal control for maximizing an objective is strongly affected by the possible existence of sub-optimal maxima. Within a unified framework under specified conditions, control objectives for maximizing at a terminal time physical observables of open classical and quantum systems are shown to be inherently free of sub-optimal maxima. This attractive feature is of central importance for enabling the discovery of controls in a seamless fashion in a wide range of phenomena transcending the quantum and classical regimes.Comment: 10 page

Randomized controlled trial of a good practice approach to treatment of childhood obesity in Malaysia: Malaysian childhood obesity treatment trial (MASCOT)

Context. Few randomized controlled trials (RCTs) of interventions for the treatment of childhood obesity have taken place outside the Western world. Aim. To test whether a good practice intervention for the treatment of childhood obesity would have a greater impact on weight status and other outcomes than a control condition in Kuala Lumpur, Malaysia. Methods. Assessor-blinded RCT of a treatment intervention in 107 obese 7- to 11-year olds. The intervention was relatively low intensity (8 hours contact over 26 weeks, group based), aiming to change child sedentary behavior, physical activity, and diet using behavior change counselling. Outcomes were measured at baseline and six months after the start of the intervention. Primary outcome was BMI z-score, other outcomes were weight change, health-related quality of life (Peds QL), objectively measured physical activity and sedentary behavior (Actigraph accelerometry over 5 days). Results. The intervention had no significant effect on BMI z score relative to control. Weight gain was reduced significantly in the intervention group compared to the control group (+1.5 kg vs. +3.5 kg, respectively, t-test p < 0.01). Changes in health-related quality of life and objectively measured physical activity and sedentary behavior favored the intervention group. Conclusions. Treatment was associated with reduced rate of weight gain, and improvements in physical activity and quality of life. More substantial benefits may require longer term and more intensive interventions which aim for more substantive lifestyle changes

Fragility of the Free-Energy Landscape of a Directed Polymer in Random Media

We examine the sensitiveness of the free-energy landscape of a directed polymer in random media with respect to various kinds of infinitesimally weak perturbation including the intriguing case of temperature-chaos. To this end, we combine the replica Bethe ansatz approach outlined in cond-mat/0112384, the mapping to a modified Sinai model and numerically exact calculations by the transfer-matrix method. Our results imply that for all the perturbations under study there is a slow crossover from a weakly perturbed regime where rare events take place to a strongly perturbed regime at larger length scales beyond the so called overlap length where typical events take place leading to chaos, i.e. a complete reshuffling of the free-energy landscape. Within the replica space, the evidence for chaos is found in the factorization of the replicated partition function induced by infinitesimal perturbations. This is the reflex of explicit replica symmetry breaking.Comment: 29 pages, Revtex4, ps figure