Development of sample preparation technique to characterize chemical structure of humin by synchrotron-radiation–based X-ray photoelectron spectroscopy

Carbon-binding state of humin (HM, a non-conductive insoluble organo-mineral humic substance) was successfully characterized for the first time by synchrotron-radiation–based X-ray photoelectron spectroscopy (XPS). Four sample preparation techniques—HM on double-sided carbon tape, indium sheet, copper mesh, and in pellet formed from the mixture of HM and copper powder (Cu) at different mixing ratios (1:1, 1:2, and 1:6 v/v)—were compared. The results show that HM samples prepared using the first three methods had significant charge buildup, which made the interpretation of the XPS spectra impossible because of the shifts in the binding energy of C 1s XPS spectra. Pellets of HM:Cu mixture enhanced the electrical conductivity and reduced charge buildup on the sample surface. Pellets prepared with HM:Cu ratio of 1:1 (v/v) provided the minimum charge buildup and high sensitivity with difference in C 1s spectra regardless of the observing position. The C 1s spectra, estimated by the subtraction of the carbon contamination in Cu, showed the resolution of CC (284.0 eV), C C/C H (285.1 eV), C O (286.3 eV), CO (287.3 eV), and OC O (288.3 eV) and three additional peaks of CF (289.3 eV), CF₂ (290.2 eV), and CF₃ (291.4 eV). Soft X-ray absorption spectroscopic (XAS) analysis further proved the existence of fluoride (F 1s) in HM structure. The detection of fluorinated carbon in HM showed a great advancement of XPS compared with other conventional analyses. X-ray with the incident angle of 0° provided the smallest (nearly negligible) energy shift in the C 1s spectra of HM and did not damage the surface of the sample.     

On the limiting distributions in Markov renewal processes with finitely many states

We are interested in some limiting distributions of M.R.P.N(t)={N _j (t), 1≤j≤r} or the total sojourn times in each state for a special M.R.P., in which transition distribution functions have the formQ _ij (t)=p _ij H _i (t). To obtain the same results for the general M.R.P. and the limiting joint distribution of {S _j (t), 1≤j≤r}, we have to use a different method, which will be stated in a paper, to appear in the near future, with examples in practical applications.     

Nature of mechanoradical formation of substituted celluloses as studied by electron spin resonance

Mechanically induced free radical (mechanoradical) formation of several substituted celluloses such as carboxylmethyl cellulose, chitin, and chitosan was studied based on electron-spin resonance (ESR) in comparison with those of plasma-induced radicals. Room temperature ESR spectra had multicomponent spectra and were different in pattern from each other. The mechanoradical concentration gradually decreased after reaching the maximum value in each substituted polysaccharide, accompanied by a decrease in molecular weight in the course of vibratory milling. One of the most intriguing facts is that the component radicals are all glucose-based radicals as in the case of plasma irradiation, although it is known that mechanoradicals are formed by 1,4-glucosidic bond cleavage of polysaccharides.     

Novel and simple preparation method of matrix-type composite particles for controlled drug release by mechanical action

Matrix-type composite particle for controlled drug release can readily be prepared through a totally dry process by simple anaerobic mechanical vibration of mechanoradical-containing ethylcellulose (EC) with theophylline powder due to occurrence of collision-induced radical-radical coupling reaction to form interparticle matrices, as well as the formation of interparticle network when solid-state vinyl monomer was further added.     

Suppression of Sea-ice Clutter Observed by a Millimeter Wave Radar

Sea-ice clutter was measured using a millimeter wave radar (MWR) with a frequency of 34.86 GHz, the beamwidth of 0.25° and pulsewidth of 30 ns which is located at Mombetsu in Hokkaido, Japan. In this paper, targets are an iron tower and a breakwater which are embedded in sea-ice clutter. We have found that the sea-ice clutter amplitude obeys the Weibull distribution. As a result of this, we obtained target to clutter ratio improvement of 22.6, 17.2 dB for an iron tower and a breakwater, respectively, by considering the modified LOG/CFAR system which is the transformation from Weibull to Rayleigh distribution.     

Stereospecific synthesis of new 4-amino-1,2,3-cyclohexanetricarboxylic acids and 4-amino-1,3-cyclohexanedicarboxylic acids

Diels-Alder adducts of 1,2-dihydropyridine with maleic and acrylic acid derivatives were stereospecifically converted by way of RuO4 oxidation into new 4-amino-1,2,3-cyclohexanetricarboxylic acids and 4-amino-1,3-cyclohexanedicarboxylic acids.     

Bochner identities for Kählerian gradients

We discuss algebraic properties for the symbols of geometric first order differential operators on Kähler manifolds. Through a study of the universal enveloping algebra and higher Casimir elements, we know a lot of relations for the symbols, which induce Bochner identities for the operators. As applications, we have vanishing theorems, eigenvalue estimates, and so on.