Temperature effects on surface activity and application in oxidation of toluene derivatives of CTAB-SDS with KMnO4

The γ_cmc values of CTAB-SDS decrease from 63.67 mN/m at 10‡C to 36.38 mN/m at 90‡C, slightly lower than those of either CTAB or SDS. Correspondingly, the CMC of CTAB-SDS decreases almost by half. The increase of surface activity of CTAB-SDS can be attributed to the relatively weak electrostatic interaction at high temperature, which is supported by the increase of solubility of CTAB-SDS with rise in temperature. Catalytic effect on oxidation of toluene derivatives with potassium permanganate follows the order CTAB-SDS > SDS > CTAB. This is not caused by the dissociative effect of CTAB-SDS with low surface activity at low temperature, as seen from the fact that almost all oxidative products can be retrieved for different toluene derivatives and surfactants by mimicking the conditions of reaction. In the emulsifications of toluene derivatives at 90‡C, the time that turbid water layers of surfactant solutions take to become clear is the same as that of the catalytic effect on oxidation of toluene derivatives. Thus, it can be inferred that surfactants can improve the oxidation yields of toluene derivatives by increasing the contact between two reacting phases.     

Effects of sodium salicylate on the febrile response and increased levels of cyclic AMP in cerebrospinal fluid during endogenous pyrogen-induced fever in rabbits

To further evaluate the causality between endogenous pyrogen (EP)-induced fever and cyclic adenosine-3',5'-monophosphate (cyclic AMP) level, the effects of sodium salicylate (SS) on the febrile response and increased levels of cyclic AMP in both cerebrospinal fluid (c.s.f.) and plasma during EP-induced fever in rabbits were observed. The results suggest that cyclic AMP is probably involved in the central mediation of EP-induced fever and that increased concentration of cyclic AMP in c.s.f. associated with EP-induced fever is not the result of temperature elevation but appears to be caused by the increased synthesis in the central nervous system. In addition it is confirmed that blood is impossibly a contributory source of increased cyclic AMP in c.s.f. during EP fever, and that SS may act subsequent to the increase in cyclic AMP.     

Microwave-assisted extraction of quercetin and acid degradation of its glycosides in Psidium guajava leaves.

Microwave-assisted extraction (MAE) and microwave-assisted hydrolysis (MAAH) were developed for the sample preparation of guava leaves prior to GC determination of quercetin and its glycosides. Ethanol was selected as the solvent. The optimum MAE temperature, particle size, solvent volume and MAE time are 120 degrees C, 40 - 60 mesh, 20 mL and 5 min, respectively; the optimum MAAH temperature and time, HCl concentration, solvent are 100 degrees C, 5 min, 1.2 mol L(-1) HCl and ethanol, respectively.     

Analytic Solution of Charge Density of Single Wall Carbon Nanotube under Conditions of Field Electron Emission

We derive the analytic solution of induced electrostatic potential along single wall carbon nanotubes. Under the hypothesis of constant density of states in the charge-neutral level, we are able to obtain the linear density of excess charge in an external field parallel to the tube axis.     

A class of subgrid-scale models preserving the symmetry group of Navier–Stokes equations

Navier–Stokes equations (NS) admit transformations which transform a solution to another solution (galilean transformation, scaling transformation, …). They also admit viscosity dependent transformations which transform a solution to a solution of another NS with different viscosity. These particular transformations are called symmetries of NS. Each of them has a physical role (such as conservation laws, …). A consistent turbulence model should then remain invariant under these symmetry transformations. Unfortunately, this is not the case of several models.In this article, a class of subgrid-scale models preserving the symmetries of NS is built. This class is then refined such that the models respect the second law of thermodynamics. One of the simplest models of the class is tested to the flow in a ventilated room. Better results than those provided by Smagorinsky and dynamic models are obtained.     

Amplification without population inversion in a three-level Λ-type system with an external coherent magnetic field

In this Letter, we investigate the amplification without inversion (AWI) in a new scheme, a three-level Λ-type system which the two lower states are coupled by an external magnetic field. We find that, owing to the presence of the external magnetic field, the absorption of the probing field is very sensitive to the relative phase of the probing and the pumping fields. By appropriately choosing the Rabi frequency of the pumping field, the Lamor frequency of the external magnetic field and the relative phase, AWI can be realized.     

STUDIES ON THE PREPARATION OF ZINC-CONTAINING ACTIVATED CARBON FIBERS AND THEIR ANTIBACTERIAL ACTIVITY

1. INTRODUCTION Microbial pollution will bring about various problems in industry and other vital fields, such as causing decomposing of materials, harming people抯 health. In order to reduce these problems, new antibacterial materials have been demanded. Recently, much attention has been paid to inorganic materials including zinc oxide [1~4]. These inorganic antibacterial materials are now substituting for organic materials to avoid releasing noxious organic molecules harmful to humans;…     

Comparison of the structures of an atomic three-valence-electron system with a nuclear three-valence-neutron system

A comparison has been made between the states of a 3-valence-electron system and a 3-valence-neutron system. The fermions are supposed to move in a sphere. The structures and internal motions of the head-states (the lowest of a given^2S+1 L ) of these systems havingL=0,S=1/2 and 3/2, and even and odd parity have been investigated. We have found that the symmetry governing the particular quantum system plays an essential role. In particular, all the nodal surfaces in the head-states originate from symmetry but not from dynamics. Consequently, the head-states of different dynamic systems have similar structures and similar internal motions.     

Nuclear track evolution by capillary condensation during etching in SSNT detectors

The microscopic process taking place during chemical etching is described in terms of a dynamic framework governed by capillary condensation. The aim is to obtain physical information on how the cone shaped tracks with curved walls evolve during chemical etching under a close examination of first principles. The results obtained with the proposed theory are compared with published values to establish their range of validity.