A sensitive enzyme-based colorimetric assay for choline-containing phospholipids

An enzyme-based colorimetric assay for choline-containing phospholipids is described. When tested with egg yolk and serum, the method proved very sensitive, correlated well with other methods and avoided turbidity problems. The method is potentially applicable to a wide variety of samples.     

Small-signal design theory and experiment for the punch-through injection transit-time oscillator

The small-signal theory of the punch-through ‘barrier-injection and transit-time’ (BARITT) diode is given and the physical mechanisms of device operation are described. Both velocity modulation and charge density modulation components of current are included and the effects of carrier diffusion in the source regions of the device are taken into account by using an equivalent small-signal conductivity for the potential barrier which controls charge injection. It is shown how carrier bunching in the source regions creates space-charge waves which propagate through the source-drain space and generate power as the associated component of current moves into anti-phase with the local electric field.Theoretical curves are presented for a typical PNP silicon device and agree well with experimental measurements of series resistance and series capacitance. A device of area 1·25 × 10^?8 m² (5 thou. diameter) and source to drain spacing of 5 μm made in $\text{5 Ω}\text{cm}$ material was found to possess negative resistance over the wide frequency range from about 5 GHz to about 12 GHz with a maximum value of about — $\text{5 Ω}$.     

The effect of inlet parameters on the performance of packed tower-regenerator

An investigation on the operation of packed tower for the regeneration of liquid desiccant is presented. A theoretical model demonstrating the effect of the system parameters is described. The experimental results are plotted to illustrate the effect of air and liquid parameters on the output variables. The regeneration process is shown to be highly dependent on the air inlet conditions, namely, temperature, humidity and flow rate. Also, the effects of the liquid temperature, concentration and flow rate is discussed. Data obtained were correlated to estimate the rate of water evaporation (regeneration rate) from values of variables that influence the rate of mass transfer in the column.     

Effect of feed pressure on the performance of the photovoltaic powered reverse osmosis seawater desalination system

This paper describes the potential of the development of a seawater desalination system that combines the technologies of reverse osmosis (RO) and photovoltaic (PV) to deliver 100 m³/day of sweet water. Silicon cells are chosen for the PV array and the polyamide thin-film composite seawater Filmtec membranes are selected for the RO system. The software ROSA is adopted to study the influences of the feed pressure on the performance of the system. It is found that as the feed pressure increases, the specific energy of the plant decreases but the percentage of recovery increases.     

Correlation between the severities of the ASTM E119 and ISO 834 fire exposures

The temperature rise in a castable refractory brick specimen of well-defined thermal properties was used to develop a correlation between the severities of the ASTM E119 and the ISO 834 fire tests. It was found that the ISO fire test is slightly less severe than the ASTM test, but the gain in fire endurance on account of conducting the test according to the ISO standard is usualy five minutes or less.     

47—THE FORM TAKEN BY THREADS LAID ON A MOVING BELT. PART II: MECHANISMS AND THEORY

It is shown that the form of a laid-down thread can be expressed mathematically by the equation of a modified cycloid when the speed ratio between the feed and the belt is within a certain range. The experimental form is found to be reasonably close to the theoretical form. The theoretical form can be predicted if the radius of the circular coil with the belt stationary, the feed speed, and the belt speed are known, The condition for laying down the thread in a form of overlapping loops is deduced. A strobo-photographic method is used to clarify the existence of different mechanisms under different conditions.     

Hydrogen liberation from the dehydrocoupling of dimethylamine–borane at room temperature by using novel and highly monodispersed RuPtNi nanocatalysts decorated with graphene oxide

Addressed herein, we reported the fabrication of the graphene oxide (GO) supported monodispersed ruthenium–platinum–nickel (RuPtNi) nanomaterials (3.40 ± 0.32 nm) to be utilized as a catalyst in the process of dimethylamine borane (DMAB) dehydrogenation. The nanoparticles were fabricated through the ultrasonication method by co-reducing the Ru³⁺, Pt²⁺ and Ni²⁺ cations and then the nanomaterials were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), inductively coupled plasma optical emission spectrometry (ICP-OES), and X-ray photoelectron spectroscopy (XPS). The fabricated nanomaterials showed outstanding efficiency and remarkable reusability in addition to their record catalytic activity at low temperatures and with extreme low concentrations. They had a significantly high turnover frequency (TOF) (727 h^?1) and low activation energy (E_a) (49.43 ± 2 kJ mol^?1) for DMAB dehydrocoupling. To the best of our knowledge, RuPtNi@GO NPs become a very promising candidate as the best catalyst ever.