A branch and search algorithm for a class of nonlinear knapsack problems

This paper discusses a class of nonlinear knapsack problems where the objective function is quadratic. The method is a branch and search procedure which includes an efficient algorithm to find the continuous (relaxed) solution and a reduction rule which computes tight lower and upper bounds on the integer variables.     

Vertical and direct integration of heterojunction phototransistors and laser diodes

An optoelectronic integrated device based on the concept of vertical and direct integration is described. Four types of integrated devices composed of multiple heterojunction phototransistors and laser diodes are developed and the devices successfully achieve thirteen functions: optical switching, amplification, thresholding, bistability, light-controlled optical bistability, light-controlled optical thresholding, tristability, set and reset functions in tristable states, set and reset functions in tetrastable states, and bistable and tristable flip-flop functions.     

Isothermal vapor-liquid equilibria for the binary systems propylene-carbon dioxide,propylene-ethylene and propylene-ethane at high pressure

isothermal vapor-liquid equilibria for the binary systems propylene-carbon dioxide, propylene-ethylene and propylene-ethane have been measured at 283.15 and 298.15 K using a static method.The equilibrium data obtained have been correlated with the total-pressure method using both the Redlich-Kwong equation of state modified by Soave and the perturbation equation proposed by Gubbins and Twu. From normal probability plots of the residuals in the correlations versus the theoretical residuals in the normal distribution, the applicability of each of these two equations has been tested statistically.Furthermore, the fugacity coefficients calculated from the virial equation have been compared with those obtained from the correlations for the low-pressure regions.     

An excitation profile study of the resonance Raman effect of I2 in solutions

The resonance Raman effect of I₂ was observed in chloroform, benzene-d₆ and tetrahydrofuran solutions with eleven exciting frequencies by Ar⁺, Kr⁺ and He-Ne lasers. Excitation profiles obtained for the ν_I-I fundamental in benzene-d₆ and tetrahydrofuran showed apparently different features from that of chloroform. It is demonstrated in a simulative calculation that the anomalous profile in the former two solvents could be caused by the interference between partial contributions to the scattering tensor, one from the locally excited state responsible for the visible absorption and the other from the charge-transfer state, both of the complex formed.     

Determination of nitrate in natural waters by flow-injection analysis

Summary Nitrate was determined in natural water samples by flow-injection spectrophotometry. It was reduced to nitrite with copperized cadmium and the nitrite thus produced reacted with p-aminoacetophenone and m-phenylenediamine. The limit of detection was about 1.5 g l^–1 for sample injections of 650 l. The sampling rate was about 40 samples h^–1 and the relative standard deviation was above 1% for 0.1–0.3 mg l^–1 nitratenitrogen. Nitrite present in the sample was determined separately and subtracted.

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Nitratbestimmung in natürlichen Wässern mit Hilfe der Fließinjektions-Analyse

Zusammenfassung Nitrat wird bei dieser Methode mit Hilfe einer Cu/Cd-Reduktionssäule zu Nitrit reduziert, das mit p-Aminoacetophenon und m-Phenylendiamin zur Reaktion gebracht wird. Die gebildete Verbindung wird spektral-photometrisch gemessen. Die Nachweisgrenze beträgt etwa 1,5 g/l bei injizierten Probevolumina von 650 l. Der Probendurchsatz beträgt 40/h. Die relative Standardabweichung liegt über 1% bei 0,1–0,3 mg/l Nitrat-Stickstoff. Vorhandenes Nitrit wird gesondert bestimmt und abgezogen.

     

Radical polymerisation of styrene in porous coordination polymers

The first radical polymerisation of styrene in porous coordination polymers has been carried out, providing stable propagating radicals (living radicals), and a specific space effect of the host frameworks on the monomer reactivity is demonstrated.     

A novel high-spin heterometallic Ni12K4 cluster incorporating large Ni-azide circles and an in situ cyanomethylated di-2-pyridyl ketone

Reaction of di-2-pyridyl ketone (dpk) with nickel acetate and azide in the presence of potassium tert-butylate as a catalytic base generates the title compound, which contains the largest [Ni(mu(1,1)-N3)]6 circles in the discrete ferromagnetically-coupled M(II)-azide cluster family, and shows an unprecedented in situ cyanomethylation of ketone.     

Determination of sulphate in natural water by flow-injection analysis

Summary Sulphate was determined in natural water samples by flow-injection analysis using dimethylsulphonazo-III as reagent. The interference by Ca was eliminated by a cation-exchanger column inserted directly after the sample injection valve. In order to ensure high sensitivity and reproducibility it was necessary to saturate the carrier solution with barium sulphate and to fill the reaction coil with ethanol-water (11) when not in use. Standard deviations were 0.94–1.2% for 6–10mg/l sulphate. The limit of detection was about 0.2mg/l. The calibration graph was linear up to 14mg/l Mg²⁺, NH ₄ ⁺ , Na⁺, K⁺, Cl^–, NO ₃ ^– , PO ₄ ^3– , HCO ₃ ^– and SiO ₃ ^2– did not interfere in the normally occurring concentrations.

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Sulfatbestimmung in natürlichem Wasser durch Flow-Injection-Analyse

Zusammenfassung Als Reagens dient Dimethylsulfonazo-III. Die Störung durch Calcium bei dieser Bestimmung wird durch eine Kationenaustauschersäule eliminiert, die direkt nach dem Probeinjektions-Ventil angeordnet ist. Zur Erhöhung der Empfindlichkeit und Reproduzierbarkeit ist es notwendig, die Trägerlösung mit Bariumsulfat zu sättigen sowie bei Nichtbenutzung des Systems den Reaktionsteil mit Ethanol-Wasser (11) zu füllen. Mit dem so modifizierten Verfahren ergaben sich Standardabweichungen von 0,94–1,2% für 6–10 mg/l Sulfat, die Nachweisgrenze liegt bei 0,2 mg/l. Die Eichkurve ist bis 14 mg/l linear. Mg²⁺, NH ₄ ⁺ , Na⁺, K⁺, Cl^–, NO ₃ ^– , PO ₄ ^3– , HCO ₃ ^– und SiO ₃ ^2– stören in den normalerweise vorkommenden Konzentrationen nicht.