19,642 research outputs found
Conductance of electrolytes in 1-propanol solutions from −40 to 25°C
Conductance data for solutions of LiCl, NaBr, NaI, KI, KSCN, RbI, Et4NI, Pr4NI, Bu4NI, Bu4NClO4, n-Am4NI, i-Am4NI, n-Hept4NI, Me2Bu2NI, MeBu3NI, EtBu3NI, i-Am3BuNI, and i-Am3BuNBPh4 in 1-propanol at –40, –30, –20, –10, 0, 10, and 25°C are communicated and discussed. Evaluation of the data is performed on the basis of a conductance equation that includes a term in c3/2. Single ion conductances at 25 and 10°C are determined with the help of transference numbers t o + (KSCN/PrOH); the data are compared to data estimated by other methods. Ion-pair association constants and their temperature dependence are discussed in terms of contact and solvent separated ion pairs, and the role of non-coulombic forces is shown with the help of an appropriate splitting of the Gibbs energy of ion-pair formation
Conductometric Studies of 1-Ethyl-3-methylimidazolium Tetrafluoroborate and 1-Butyl-3-methylimidazolium Tetrafluoroborate in 1-Propanol at Temperatures from (283.15 to 318.15) K
The electrical conductances of dilute solutions of the ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate [emim][BF4] and 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4] in 1-propanol have been measured in the temperature range from (283.15 to 308.15) K at 5 K intervals. The ionic association constant, KA, limiting molar conductances, Λo, and distance parameters, R, were obtained using the low concentration Chemical Model (lcCM). The examined electrolytes are strongly associated in 1-propanol in the whole temperature range. From the temperature dependence of the limiting molar conductivities the Eyring’s activation enthalpy of charge transport was estimated. The thermodynamic functions such as Gibbs energy, entropy, and enthalpy of the process of ion pair formation were calculated from the temperature dependence of the association constants
Ni(II), Pd(II) and Pt(II) complexes with ligand containing thiosemicarbazone and semicarbazone moiety: synthesis, characterization and biological investigation
The synthesis of nickel(II), palladium(II) and platinum(II) complexes with thiosemicarbazone and semicarbazone of p-tolualdehyde are reported. All the new compounds were characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, 1H-NMR, IR and electronic spectral studies. Based on the molar conductance measurements in DMSO, the complexes may be formulated as [Ni(L)2Cl2] and [M(L)2]Cl2 (where M = Pd(II) and Pt(II)) due to their non-electrolytic and 1:2 electrolytic nature, respectively. The spectral data are consistent with an octahedral geometry around Ni(II) and a square planar geometry for Pd(II) and Pt(II), in which the ligands act as bidentate chelating agents, coordinated through the nitrogen and sulphur/oxygen atoms. The ligands and their metal complexes were screened in vitro against fungal species Alternaria alternata, Aspergillus niger and Fusarium odum, using the food poison technique
On the influence of molecular structure on the conductivity of electrolyte solutions - sodium nitrate in water
Theoretical calculations of the conductivity of sodium nitrate in water are
presented and compared with experimental measurements. The method of direct
correlation force in the framework of the interionic theory is used for the
calculation of transport properties in connection with the associative mean
spherical approximation (AMSA). The effective interactions between ions in
solutions are derived with the help of Monte Carlo and Molecular Dynamics
calculations on the Born-Oppenheimer level. This work is based on earlier
theoretical and experimental studies of the structure of concentrated aqueous
sodium nitrate solutions.Comment: 12 pages, 9 figure
Controlled delivery of membrane proteins to artificial lipid bilayers by nystatin-ergosterol modulated vesicle fusion
The study of ion channels and other membrane proteins and their potential use as biosensors and drug screening targets require their reconstitution in an artificial membrane. These applications would greatly benefit from microfabricated devices in which stable artificial lipid bilayers can be rapidly and reliably formed. However, the amount of protein delivered to the bilayer must be carefully controlled. A vesicle fusion technique is investigated where composite ion channels of the polyene antibiotic nystatin and the sterol ergosterol are employed to render protein-carrying vesicles fusogenic After fusion with an ergosterol-free artificial bilayer the nystatin-ergosterol channels do not dissociate immediately and thus cause a transient current signal that marks the vesicle fusion event. Experimental pitfalls of this method were identified, the influence of the nystatin and ergosterol concentration on the fusion rate and the shape of the fusion event marker was explored, and the number of different lipid was reduced. Under these conditions, the B-amyloid peptide could be delivered in a controlled manner to a standard planar bilayer. Additionally, the electrical recordings were obtained of vesicles fusing with a planar lipid bilayer in a microfabricated device, demonstrating the suitability of nystatin-ergosterol modulated vesicle fusion for protein delivery within microsystems
Changes in single K+ channel behavior through the lipid phase transition
We show that the activity of an ion channel is strictly related to the phase
state of the lipid bilayer hosting the channel. By measuring unitary
conductance, dwell times, and open probability of the K+ channel KcsA as a
function of temperature in lipid bilayers composed of POPE and POPG in
different relative proportions, we obtain that all those properties show a
trend inversion when the bilayer is in the transition region between the liquid
disordered and the solid ordered phase. These data suggest that the physical
properties of the lipid bilayer influence ion channel activity likely via a
fine tuning of its conformations. In a more general interpretative framework,
we suggest that other parameters such as pH, ionic strength, and the action of
amphiphilic drugs can affect the physical behavior of the lipid bilayer in a
fashion similar to temperature changes resulting in functional changes of
transmembrane proteins
Schottky barrier and contact resistance of InSb nanowire field effect transistors
Understanding of the electrical contact properties of semiconductor nanowire
(NW) field effect transistors (FETs) plays a crucial role in employing
semiconducting NWs as building blocks for future nanoelectronic devices and in
the study of fundamental physics problems. Here, we report on a study of the
contact properties of Ti/Au, a widely used contact metal combination, to
individual InSb NWs via both two-probe and four-probe transport measurements.
We show that a Schottky barrier of height is
present at the metal-InSb NW interfaces and its effective height is gate
tunable. The contact resistance () in the InSb NWFETs is also
analyzed by magnetotransport measurements at low temperatures. It is found that
at on-state exhibits a pronounced magnetic field dependent
feature, namely it is increased strongly with increasing magnetic field after
an onset field . A qualitative picture that takes into account
magnetic depopulation of subbands in the NWs is provided to explain the
observation. Our results provide a solid experimental evidence for the presence
of a Schottky barrier at Ti/Au-InSb NW interfaces and can be used as a basis
for design and fabrication of novel InSb NW based nanoelectronic devices and
quantum devices.Comment: 12 pages, 4 figure
Properties of nonaqueous electrolytes Quarterly report, 20 Dec. 1966 - 19 Mar. 1967
Properties of nonaqueous electrolytes - preparation of electrolytes, nuclear magnetic resonance structural studies, and physical property determination
- …