The comparative study of biocomposites based on hydrochar and chitosan-modified urea-formaldehyde resins

To provide new insight into the field of urea-formaldehyde (UF) adhesives science, in this work, for the first time, UF resin was modified with hydrochar of spent mushroom substrate (HCUF) and chitosan (CHUF) to investigate the effect of these bio-fillers on the hydrolytic and thermal stability of in situ prepared UF resins. The characterization of the modified UF biocomposites was performed using X-ray diffraction analysis (XRD), Fourier transforms infrared spectroscopy (FTIR), non-isothermal thermogravimetric analysis (TG), differential thermal gravimetry (DTG), and differential thermal analysis (DTA). Scanning electron micrographs (SEM) of the CHUF and HCUF biocomposites show a spherical structure that differs from each other because the surface of the CHUF biocomposite has pronounced pores that form a network structure. With its hydroxyl and amino groups, chitosan bonding to UF resin through hydrogen bonds, which is confirmed by FTIR analysis. The content of free FA in CHUF biocomposite is 0.06%, while that of HCUF is higher and amounts to 0.48%. The content of released FA in both modified UF biocomposites was similar (2.5% and 2.8% for CHUF and HCUF, respectively). The hydrolytic stability of CHUF is slightly higher compared to the HCUF biocomposite. Thermal analysis shows that the CHUF is thermally more stable because it starts to decompose at a slightly higher temperature than the HCUF biocomposite.     

Deposition of silver ions onto DBD and DCSBD plasma treated nonwoven polypropylene

The aim of this work is plasma activation of nonwoven polypropylene (PP) using two different ambient air plasma sources: volume dielectric barrier discharge (DBD) and diffuse coplanar surface barrier discharge (DCSBD) and its functionalization by silver ion deposition.     

Statistical Density Estimation Using Threshold Dynamics for Geometric Motion

Our goal is to estimate a probability density based on discrete point data via segmentation techniques. Since point data may represent certain activities, such as crime, our method can be successfully used for detecting regions of high activity. In this work we design a binary segmentation version of the well-known Maximum Penalized Likelihood Estimation (MPLE) model, as well as a minimization algorithm based on thresholding dynamics originally proposed by Merriman et al. (The Computational Crystal Growers, pp. 73–83, 1992). We also present some computational examples, including one with actual residential burglary data from the San Fernando Valley.     

Association of autonomic neuropathies and gastrointestinal peptides in non-insulin dependent diabetics

Basal and postprandial levels of gastrin, somatostatin, vasoactive intestinal polypeptide (VIP) and pancreatic polypeptide (PP) were followed up in 105 patients with non insulin dependent diabetes mellitus (20 with autonomic neuropathy only, 35 with peripheric neuropathy only, 30 with autonomic and peripheric neuropathy simultaneously and 20 without any sign of neuropathy) and in the control group of 40 individuals. Serum levels of gastrin, somatostatin, VIP and PP are determined by a RIA (used kits of Prof. SR Bloom, Hammersmith Hospital, London). The results of investigation showed significantly higher basal and postprandial levels of gastrin and VIP in patients with autonomic neuropathy in comparison with the group without neuropathy and with the control group (p < 0.001). The serum levels of somatostatin did not differ significantly between the groups of diabetics with and without neuropathy. Basal level of PP was significantly lower and postprandial PP levels remained low in patients with autonomic neuropathy in comparison with the group without neuropathy (p < 0.001). We postulate that basal and postprandial gastrin and VIP levels raised secondary to partial vagotomy in diabetics with autonomic neuropathy. Measuring PP serum levels in diabetics after a protein rich meal can be useful to check vagus nerve function in the gastrointestinal tract in order to detect autonomic neuropathy.     

Investigation in the sintering of Y2O3 powders in the temperature range 1000 to 1400° C

This paper is devoted to a study of the sintering of two Y₂O₃ powders in the temperature range where only minor densification occurs. Two powders have been examined; one powder, Y₂O₃-A, was obtained by decomposition of hydroxide, because earlier examinations showed [11] that use of this powder resulted in the highest densities of samples in the sintering temperature range from 1300 to 1900° C. The second powder, Y₂O₃-D, was purchased externally. In order to ensure that the pores in the Y₂O₃-A compacts closed as late as possible, the heating rates up to the appropriate temperatures (1000 to 1400° C) were varied in the range 0.013 to 6° C sec^–1. The results obtained show that the heating rate in this temperature range, for the powder obtained by decomposition of hydroxide, is of primary importance in the densification of the material, and that cessation of shrinkage was not observed in the period of 240 min.     

Error rates of phase-modulated signals in multilink system with interference

The error probabilities for M-fold coherent and differentially coherent phase-shift keying signals passed through a multi-link system composed of cascaded linear amplifiers is found. At each link Gaussian noise and cochannel interference are additively injected.