A note on the solution of a class of two-point boundary value problems involving a mixed boundary condition

In this note, we consider a class of two-point boundary value problems involving a pa- rameter in one of the boundary conditions. We shall show that if we know the solution corresponding to a particular value of the parameter, then the solution for any other value of the parameter can be obtained by a simple algebraic method.     

Growth of InP/InGaAs multiple quantum well structures by chemical beam epitaxy

InP/InGaAs multiple quantum well structures with up to 200 periods have been grown by CBE. These structures exhibit exceptional lateral uniformity, measured as ±1 Å in period, ±13 ppm in lattice mismatch and ±0.5 nm in wavelength across a 2 inch wafer. Good surface morphology, sharp interfaces and excellent growth control have all been demonstrated.     

Barrier Discharge The Transferred Charge and Ozone Synthesis

We have undertaken an experimental investigation of the influence of the conditions of barrier discharge implementation such as: the discharge gap value, the type of gas, and the polarity and dielectric permittivity of the dielectric electrode on the value of charge transferred in a micro-discharge. It is shown that the increase in the specific capacitance of the electrodes leads to proportional increase in the transferred charge value, reaching 100–200 nC in a discharge gap 1 mm, in air. In this case the amplitude and duration of a current pulse in the microdischarge reach, respectively, 10 to 15 A and 40 ns. It is also demonstrated that in air with increase in the discharge gap value one can observe a decrease in the efficiency of the ozone synthesis whereas in oxygen there exists a more complicated dependence: the maximum of efficiency is observed at a discharge gap value of 0.7 to 1.0 mm.     

Separability and distance

Translated from Matematicheskie Zametki, Vol. 50, No. 5, pp. 18–22, November, 1991.     

The complete set of symmetry operators of the schrödinger equation

The complete set of symmetry operators of an arbitrary order associated with the Schrödinger equation is found. It is shown that this equation is invariant with respect to a 28-dimensional Lie algebra, realized in the class of differential operators of the second order. Higher-order symmetries of the Levi-Leblond equation are investigated.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 11, pp. 1521–1526, November, 1991.     

Reactions of the nitrate radical with a series of reduced organic sulphur compounds in air

A 480 L evacuable reaction chamber, equipped with FT-IR spectroscopy on-line and ion chromatography off-line, has been used to study the gas phase reaction between the nitrate radical, NO₃, and the reduced organic sulphur compounds CH₃CH₂SH, (CH₃CH₂)₂S, (CH₃CH₂)₂S₂, and CH₃CH₂SCH₃ in air. The products CH₃CH₂SO₃H, SO₂, H₂SO₄, CH₃CHO, and CH₃CH₂ONO₂ were identified and quantified in the reactions of the first three compounds, CH₃CH₂SH, (CH₃CH₂)₂S, and (CH₃CH₂)₂S₂. The reaction products were CH₃CH₂SO₃H, CH₃SO₃H, SO₂, H₂SO₄, CH₃CHO, and CH₂O in the reaction of CH₃CH₂SCH₃. On the basis of identified reaction products and intermediates observed in the infrared spectra, mechanisms are proposed for the reactions between the NO₃ radical and the four reduced organic sulphur compounds. The results of this study, together with those from previous experiments performed in this laboratory on CH₃SCH₃, CH₃SH, and CH₃SSCH₃ lead to the conclusion that all these species, in the reaction with the NO₃ radical, follow a similar degradation mechanism producing SO₂, H₂SO₄, R? SO₃H, R? CHO, and R? CH₂ONO₂, as the main reaction products. The inital step of the reaction of NO₃ with R? S? R and R? S? H type (R = CH₃, CH₂CH₃) reduced organic sulphur compounds was found to be H-atom abstraction, probably after the formation of an initial adduct. For the reaction between NO₃ and R? S? S? R type compounds, evidence for an addition-decomposition reaction, as the initial steps, was obtained. R? S·, R? S(O)·, and R? S(O)₂· appear to be formed as intermediates in all the reactions. © John Wiley & Sons, Inc.     

Analysis of fragrance compounds in blood samples of mice by gas chromatography, mass spectrometry, GC/FTIR and GC/AES after inhalation of sandalwood oil.

After inhalation experiments with sandalwood oil and the pure fragrance compounds coumarin and alpha-terpineol, substances were detected and measured in the blood samples of test animals (mice) using gas chromatography/mass spectrometry (GC/MS) (MID) in connection with GC/FTIR (SWC), GC/AES (carbon and oxygen trace) and flame ionization detection/gas chromatography. Using tiglinic acid benzyl ester as the internal standard the following concentrations in serum could be found: alpha-santalol 6.1 ng/mL, beta-santalol 5.3 ng/mL and alpha-santalene 0.5 ng/mL. In separate inhalation experiments with coumarin and with alpha-terpineol the corresponding concentrations were 7.7 ng/mL and 6.9 ng/mL, respectively.     

Alfven's programme in solar system physics

Hannes Alfven's research program in solar system physics provides a valuable case study for the historians and philosophers of science. The response of the scientific community to his remarkable contributions is a severe test of widely held views about how science is or should be done. Seven of those contributions are examined, in the light of two doctrines of scientific methodology, those of Karl Popper (1959) and Imre Lakatos (1978). The seven are: application of the magnetic braking concept to the origin of the solar system; magnetohydrodynamic waves; field-aligned (`Birkeland') currents; critical ionization velocity and the existence of planetary rings; jet streams; electrostatic double layers; and partial corotation