Mechanism for degradation of poly(sodium acrylate) by bacterial consortium no. L7-98

Poly(sodium acrylate) (PSA) can be degraded by consortia of several bacterial species. We investigated the degradation mechanism for PSA (average molecular weight, 2100) by consortium no. L7-98. PSA was used as the sole carbon source in a mineral salt medium. After cultivation, the PSA had a range of molecular weights, including low-molecular-weight compounds, which were purified by gel-permeation and reversed-phase column chromatography. One purified compound, B1, with the molecular weight of 200, had a carbonyl group next to the terminus, according to 1H and 13C nuclear magnetic resonance spectrometry and X-ray analysis of the crystal structure. Two categories of metabolites of PSA were detected in the culture by electrospray ionization mass spectrometry. Results of high-resolution mass spectrometry (HR-MS) suggested that one kind of compounds had a carbonyl group and that the other kind of compounds had an aldehyde group and a double bond. Compounds having the molecular weights of 200 and 272 were rapidly produced from an acrylic acid oligomer with the molecular weight of 258 by resting cells of the consortium. HR-MS showed that a methylene group at the terminal unit was oxidized to a carbonyl group and that the compound with the molecular weight of 200 was compound B1. From these results, we propose that the degradation pathway of PSA involves (i) oxidation of a methylene group to a carbonyl group next to the terminus, (ii) decarboxylation to form an aldehyde group and dehydrogenation to form a double bond between the terminal unit and the next unit, and (iii) oxidation of the aldehyde group to a carboxyl group followed by elimination of an acetic acid.     

Experimental studies on the optimization of the accelerating field distribution in an IH lineac

A new method is being studied to control the accelerating field distribution in an IH lineac with a high energy gain. In spite of its high shunt impedance, a shortcoming of an IH structure is that a concentration of accelerating field occurs at the low-energy section of the cavity. One of the practical methods to control the accelerating-gap voltages is adjusting the electric-capacity distribution of the structure. This method, however, is not always suitable for an IH lineac when the particle-energy gain is larger than the incident particle energy.The basic idea of our experiments is to utilize an inductive method to “tune” the accelerating field distribution. In order to test the applicability of this method, accelerating field distributions and shunt impedances are measured in terms of these “tuner” configurations by using $\text{1}\text{4}$ scale models. The results are compared with the calculations based on a four-terminal network simulation.     

Position-, size-, and shape-controlled highly crystalline ZnO nanostructures

Highly ordered ZnO nanoboxes and nanowire structures with a width of ～ 20 nm have been successfully fabricated by the combination of nanoimprint lithography and pulsed laser deposition utilizing a glancing angle deposition (GLAD) technique. The periodicity, size, and shape of the ZnO nanoboxes and nanobelts can be easily controlled over a large area by changing the molds and deposition conditions. At the initial stage of growth by GLAD, nanonucleation led to nanopillar structures, which agglomerated to form nanobox and nanobelt structures at room temperature (RT). The ZnO nanostructures have a c-axis orientation along the nanopillar direction after postannealing and exhibit an intense cathodoluminescence peak around 380 nm at RT.     

Attempt to extract features and classify subjective poor physical conditions in facial images using deep metric learning

Artificial Life and Robotics - With the spread of COVID-19, the need for remote detection of physical conditions is increasing, for example, there are several situations wherein the body...