Authors:L. Chen, Y. Tian, S. Chen, and O. Liesenfeld
Rapid and accurate diagnosis of influenza is important for patient management and infection control. We determined the performance of the cobas® Influenza A/B assay, a rapid automated nucleic acid assay performed on the cobas® Liat System for qualitative detection of influenza A and influenza B from nasopharyngeal (NP) swab specimens. Retrospective frozen and prospectively collected NP swabs from patients with signs and symptoms of influenza collected in universal transport medium (UTM) were tested at multiple sites including CLIA-waived sites using the cobas® Influenza A/B assay. Results were compared to the Prodesse ProFlu+ assay and to viral culture. Compared to the Prodesse ProFlu+ Assay, sensitivities of the cobas® Influenza A/B assay for influenza A and B were 97.7 and 98.6%, respectively; specificity was 99.2 and 99.4%. Compared to viral culture, the cobas® Influenza A/B assay showed sensitivities of 97.5 and 96.9% for influenza virus A and B, respectively; specificities were 97.9% for both viruses. Polymerase chain reaction (PCR)/sequencing showed that the majority of viral culture negative but cobas® Influenza A/B positive results were true positive results, indicating that the cobas® Influenza A/B assay has higher sensitivity compared to viral culture.
In conclusion, the excellent accuracy, rapid time to result, and remarkable ease of use make the cobas® Influenza A/B nucleic acid assay for use on the cobas® Liat System a highly suitable point-of-care solution for the management of patients with suspected influenza A and B infection.
Authors:Y. Wen, H. Liu, L. Tian, P. Han, and F. Luan
A simple and rapid capillary electrophoretic procedure for analysis of matrine and oxymatrine in Kushen medicinal preparations has been developed and optimized. Orthogonal design was used to optimize the separation and detection conditions for the two active components. Phosphate concentration, applied potential, organic modifier content, and buffer pH were selected as variable conditions. The optimized background electrolyte contained 70 mM sodium dihydrogen phosphate and 30% acetonitrile at pH 5.5; the separation potential was 20 kV. Each analysis was complete within 5 min. Regression equations revealed linear relationships (r > 0.999) between peak area and amount for each component. The detection limits were 1.29 μg mL−1 for matrine and 1.48 μg mL−1 for oxymatrine. The levels of the two active compounds in two kinds of traditional Chinese medicinal preparation were easily determined with recoveries of 96.57–106.26%. In addition, multiple linear regression and a non-linear model using a radial basis function neural network approach were constructed for prediction of the migration time of oxymatrine. The predicted results were in good agreement with the experimental values, indicating that a radial basis function neural network is a potential means of prediction of separation time in capillary electrophoresis.
Complexation of neptunium(V) with fluoride in aqueous solutions at elevated temperatures was studied by spectrophotometry
and microcalorimetry. Two successive complexes, NpO2F(aq) and NpO2F2−, were identified by spectrophotometry in the temperature range of 10–70°C. Thermodynamic parameters, including the equilibrium
constants and enthalpy of complexation between Np(V) and fluoride at 10–70°C were determined. Results show that the complexation
of Np(V) with fluoride is endothermic and that the complexation is enhanced by the increase in temperature — a two-fold increase
in the stability constants of NpO2F(aq) and more than five-fold increase in the stability constants of NpO2F2− as the temperature is increased from 10 to 70°C.
Sulfate, one of the inorganic constituents in the groundwater of nuclear waste repository, could affect the migration of radioactive
materials by forming complexes. Spectrophotometric and microcalorimetric titrations were performed to identify the Np(V)/sulfate
complex and determine the equilibrium constants and enthalpy of complexation at 10–70°C.
Results show that the complexation of Np(V) with sulfate is weak but slightly enhanced by the increase in temperature. The
complexation is endothermic and becomes more endothermic with the increase in temperature. The enhanced complexation at elevated
temperatures is due to the increasingly larger entropy of complexation that exceeds the increase in enthalpy, indicating that
the complexation of Np(V) with sulfate is entropy-driven.
The complexes of [Sm(o-MOBA)3bipy]2·H2O and [Sm(m-MOBA)3bipy]2·H2O (o(m)-MOBA = o(m)-methoxybenzoic acid, bipy-2,2′-bipyridine) have been synthesized and characterized by elemental analysis, IR, UV, XRD and
molar conductance, respectively. The thermal decomposition processes of the two complexes were studied by means of TG–DTG
and IR techniques. The thermal decomposition kinetics of them were investigated from analysis of the TG and DTG curves by
jointly using advanced double equal-double steps method and Starink method. The kinetic parameters (activation energy E and pre-exponential factor A) and thermodynamic parameters (ΔH≠, ΔG≠ and ΔS≠) of the second-step decomposition process for the two complexes were obtained, respectively.
In this study, the thermal stability of sisal in cycle process was investigated between room temperatures and 600°C in various
conditions (in air, in composites, in argon) by thermogravimetry and mechanical testing measurement. The results indicated
that the thermal stability of sisal was worse in air before five times of thermal cycles, but after the five times thermal
stability of sisal in composites was better. In different conditions of same cycles process, the thermal stability of sisal
was different. With increasing of thermal cycles times, the max. load (is the maximum strength in stress-strain curve) of
sisal fiber showed downtendency in different conditions and decreased most obviously in composites.
Authors:F. Tian, L. Sun, J. Venart, R. Prasad, and S. Mojumdar
Various techniques and methodologies of thermal conductivity measurement have been based on the determination of the rate
of directional heat flow through a material having a unit temperature differential between its opposing faces. The constancy
of the rate depends on the material density, its thermal resistance and the heat flow path itself. The last of these variables
contributes most significantly to the true value of steady-state axial and radial heat dissipation depending on the magnitude
of transient thermal diffusivity along these directions. The transient hot-wire technique is broadly used for absolute measurements
of the thermal conductivity of fluids. Refinement of this method has resulted in a capability for accurate and simultaneous
measurement of both thermal conductivity and thermal diffusivity together with the determination of the specific heat. However,
these measurements, especially those for the thermal diffusivity, may be significantly influenced by fluid radiation. Recently
developed corrections have been used to examine this assumption and rectify the influence of even weak fluid radiation. A
thermal conductivity cell for measurement of the thermal properties of electrically conducting fluids has been developed and
The paper describes a new transient hot wire instrument which employs 25.4 μm diameter tantalum wire with an insulating tantalum
pentoxide coating. This hot-wire cell with a thin insulating layer is suitable for measurement of the thermal conductivity
and the thermal diffusivity of electrically conducting and polar liquids. This instrument has been used for experimental measurement
of the thermal conductivity and the thermal diffusivity of poly(acrylic acid) solution (50 mass%) in the temperature range
of 299 to 368 K at atmospheric pressure. The thermal conductivity data is estimated to be accurate within ±4%. Thermal diffusivity
measurements have a much higher uncertainty (±30%) and need further refinement.
Authors:Y. Shi, L. Sun, F. Tian, J. Venart, and R. Prasad
The transient hot-wire technique is widely used for absolute measurements of the thermal conductivity of fluids. Refinement
of this method has resulted in a capability for accurate and simultaneous measurement of both thermal conductivity and thermal
diffusivity together with a determination of the specific heat. However, these measurements, especially those for the thermal
diffusivity, may be significantly influenced by fluid radiation.
The present work investigates the effect of fluid radiation on the measurements of the thermal conductivity of propane. Recently
developed corrections have been used to examine this assumption and rectify the influence of even weak fluid radiation. Measurements
at 372 K with a hot-wire instrument demonstrate the presence of radiation effects in both the liquid and vapor phase. The
influence is much more pronounced in liquid propane at 15.5 MPa than in the vapor phase at 881.5 kPa. The technique employed
to obtain radiation-free thermal conductivity measurements is described.
Authors:F. Tian, L. Sun, S. C. Mojumdar, J. E. S. Venart, and R. C. Prasad
The transient hot-wire method is considered the most accurate technique to measure the thermal conductivity of fluids. In this study, a transient hot wire instrument which employs 25.4-μm-diameter tantalum wire with an insulating tantalum pentoxide coating has been used. This hot-wire cell with a thin insulating layer is suitable for measurement of the thermal conductivity of electrically conducting and polar liquids. Measurements of the thermal conductivity of 50 wt% solution of PAA [poly (acrylic acid)] in water and PAA–Na in 50 wt% water are reported here. These measurements were obtained in the temperature range of 299–368 K at 1 atmospheric pressure. The measurement of thermal conductivity is estimated to be accurate within ±4%.