The Fast Numerical Solution of Very Large Elliptic Difference Schemes

Let L_kv_k = g_k be a system of difference equations discretizingan elliptic boundary value problem. Assume the system to be"very large", that means that the number of unknowns exceedsthe capacity of storage. We present a method for solving theproblem with much less storage requirement. For two-dimensionalproblems the size of the needed storage decreases from O(h^–2)to (or even O(h^–5/4)). The computational work increasesonly by a factor about six. The technique can be generalizedto nonlinear problems. The algorithm is also useful for computerswith a small number of parallel processors.     

LOW COST DIGITAL SPECTRORADIOMETER*

Abstract— A self-made low cost digitized single beam spectroradiometer is described. It is designed and calibrated to measure spectral radiant intensities in one nanometer steps for bandwidths between 1 and 20 nm within the wavelength range 200–1100 nm. The voltage output of the photoelectric detector-system is proportional to the logarithm of the received irradiance and so constant signal resolution is gained over more than three orders of radiant intensities. Raw data recording and processing is done by a common 8 bit microcomputer, programmed in Microsoft Basic. Scanned emission spectra of a far-red fluorescent lamp and a long arc xenon discharge lamp are presented and compared to manufacturer's data. In addition, the emission spectrum of a blue fluorescent tube has been determined to test for photometric aptitude. In this context the integral irradiances have been both measured and calculated for three radiometric sensors of defined spectral responsivities, indicating reliability of the instrumentation.     

Laterally 4-nitrobenzyloxycarbonyl substituted phenyl benzoates: The first two-ring mesogens with a lateral branch containing a phenyl ring

The synthesis and properties of laterally 4-nitrobenzyloxycarbonyl substituted phenyl benzoates are described; these compounds represent the first two-ring mesogens having a phenyl ring in the lateral branch. The lengths of the terminal chains of the core carrying the branch have a great influence, as shown by the phase behaviour of two homologous series. Compounds having long alkyloxy groups exhibit enantiotropic smectic A phases. It should be emphasized that the mesophase thermal stability of these strongly branched derivatives can be higher than that of the laterally unsubstituted parent compound. Connecting two of the new mesogens by means of an aliphatic spacer results in a novel type of twin molecule.     

WAVELENGTH-DEPENDENT ACTION DICHROISM: A THEORETICAL CONSIDERATION

Abstract— For a model structure the wavelength dependence of action dichroism is computed as a function of the angle(△) between the transition moments at two different wavelengths. With as small an angle as △ α = 20. inversion of action dichroism for parallel vs perpendicularly vibrating radiation is expected for different absorption bands if the sensory pigment molecules are in proper orientations. Thus published data on opposite action dichroism in the blue vs near-UV range are compatible with flavins as sensory pigments, although the calculations must not be considered as proof for the flavin hypothesis.     

EFFECT OF LIGHT QUALITY ON THE in vitro THYLAKOID PROTEIN PHOSPHORYLATION IN THE GREEN ALGA Scenedesmus obliquus

Abstract Thylakoid protein phosphorylation was assayed in vitro with isolated thylakoids of Scenedesmus obliquus by irradiation with monochromatic light of different wavelengths and equal photon fluences. The action spectrum for light-activated protein phosphorylation showed two maxima at 450 and 679 nm. A minimum of activity was reached around 580 nm. At this wavelength, the level of protein phosphorylation barely differed from that of dark-incubated samples. The action spectrum of thylakoid protein phosphorylation resembled the chlorophyll absorption spectrum obtained in vivo. The results show that chlorophyll is the photoreceptor for thylakoid membrane phosphorylation.     

The ArNe-N2O van der Waals trimer: a high resolution spectroscopic study of its rotational spectrum,structure and dynamics

A new ternary van der Waals complex of the type rare gas-rare gas'-linear molecule, ArNe-N₂O, was investigated using a pulsed molecular beam cavity Fourier transform microwave spectrometer. The rotational spectra of six isotopomers of the trimer were studied in detail. These include Ar²⁰Ne-¹⁴N¹⁴NO, Ar²²Ne-¹⁴N¹⁴NO, Ar²⁰Ne-15N¹⁴NO, Ar²²Ne-¹⁵N¹⁴N0, Ar²⁰Ne-¹⁴N¹⁵NO and Ar²²Ne-¹⁴N¹⁵NO. Nuclear quadrupole hyperfine structures of the rotational transitions that are due to the one or two ¹⁴N nuclei were resolved and analysed. The resulting spectroscopic constants were used to provide structural and dynamical information about the trimer. Based on the quartic centrifugal distortion constants, a harmonic force field analysis was performed to estimate the frequencies of the van der Waals vibrational modes. A perturbation of the electronic charge distribution at the site of the central ¹⁴N nucleus of N²0 upon complex formation was detected and discussed. Differences of structural parameters of the trimer as compared to those of the respective dimer units are indicative of the presence of significant three-body non-additive contributions to the interaction energy.     

The structure of carbodiimide,HNCNH

An experimentally determined r _s -type structure of HNCNH is reported: r _NH = 1.0074 Å, r _CN = 1.2242 Å, ∠HNC = 118.63°, ∠NCN = 170.63°, ∠HN ··· NH = 88.99°. The number of digits quoted allow for errors with two significant figures. In order to obtain these values we recorded rotational—torsional spectra of HN¹³CNH, H¹⁵NC¹⁵NH and DNCND, by using isotopically enriched cyanamide. A chemical equilibrium exists between carbodiimide, HNCNH, and the more stable isomer cyanamide, H₂NCN, which strongly favours cyanamide (approximately 1:115 at 110 °C). The expensive C- and N-substituted isotopomers could only be investigated in the millimetre wave region, while for DNCND the far infrared spectrum between 10–350 cm^?1 was also recorded. Rotational constants of the three isotopomers, as well as of the parent species, were determined by fitting the assigned spectral transitions to the Watson Hamiltonian in S reduction. Using fitting programs written by Schwendeman and Rudolph, r _o, r_s and r^ρ _m structures of HNCNH were derived. The experimentally determined structural parameters are compared with an ab initio r_e structure.     

The sensitive detection of NO by Faraday modulation spectroscopy with a quantum cascade laser

A spectrometer based on a quantum cascade laser and capable of operating at particular wavelengths in the mid-infrared with very high sensitivity for the detection of open-shell molecules has been developed. It exploits magnetic field modulation in the Faraday rotation configuration. The signals for nitric oxide (NO) that may be observed with this instrument have been studied and their dependence on the J and Ω quantum numbers investigated with a simulation program. It is shown that the Q(3/2) transition of NO in the ²Π_3/2 component at 1875.8 cm^?1 would provide the greatest sensitivity for detection. The experimental observation of the R(21/2) transition of the Ω = 1/2 component gives a detection limit of 41 ppb of NO in air at a pressure of 25 mbar. Detection of NO through the Q(3/2) transition would provide a detection limit of 4 ppb at this pressure.