Analysis of microbial community biodiversity in activated sludge from a petrochemical plant

Theactive sludge process is one of the most-used techniques for the biodegradation of organic compounds present in effluents from an assortment of wastewaters. This study investigated the bacterial community structure of a petroleum industry’s activated sludge and its physical and chemical parameters using high-throughput sequencing. Samples were collected over one year: autumn 2015 (C1), winter 2015 (C2), spring 2015 (C3), and summer 2016 (C4). Total DNA was extracted, and the primers targeting the V4 region of the 16S rRNA gene were used for amplicon sequencing. The majority of the detected microorganisms were considered rare microbiota, presenting a relative abundance below 1% of the total sequences. All of the sequences were classified at the phylum level, and up to 55% of the ASVs (Amplicon Sequence Variants) were associated with known bacterial genera. Proteobacteria was the most abundant phylum in three seasons, while the phylum Armatimonadota dominated in one season. The genus Hyphomicrobium was the most abundant in autumn, winter and summer, and an ASV belonging to the family Fimbriimonadaceae was the most abundant in the spring. Canonical Correspondence Analysis showed that physicochemical parameters of SS, SD and TSS are correlated, as well as ammoniacal nitrogen. Sample C3 presented the highest values of COD, AN and solids (SS, SD and TSS). The highest COD, AN, and solids values are correlated to the high frequency of the phylum Armatimonadota in C3.

Electrically Detected Magnetic Resonance (EDMR) Studies of SiC-SiO2 Interfaces

We discuss the results of electrically detected magnetic resonance (EDMR) spectroscopy on SiC-SiO2 interfaces interacting with hydrogen and nitrogen. Using EDMR, three types of 4H-SiC MOSFETs, which were prepared by dry oxidation (“Dry” sample), post hydrogen anneal (“Hydrogen” sample), and post nitridation anneal (“Nitrogen” sample), were examined in the temperature range of 4–300 K. These samples revealed several different results from the earlier ESR (electron spin resonance) and EDMR studies on SiC-SiO2 interfaces. The most significant finding was the high-density doping of nitrogen into the channel region after the post nitridation anneal. The incorporated nitrogen donors were observed as the “Nh” EDMR signal at 4–20 K. Roles of these nitrogen donors are discussed in correlation with the electrical properties of SiC MOSFETs.

84 SUCCESSFUL CRYOPRESERVATION OF PORCINE EMBRYOS BY THE METAL MESH VITRIFICATION (MMV) METHOD

The present study was designed to generate piglets from porcine embryos by the metal mesh vitrification (MMV) method. Prepuberal gilts were administered eCG and hCG and were artificially inseminated. Morulae and expanding blastocysts (diameter = approximately 200 μm) were collected at 144 h and 168 h after hCG injection, respectively. The metal mesh and the plastic plate (control) were used as sample containers for ultrarapid vitrification. The metal mesh (75 μm stainless steel mesh) was 1.5 mm wide and 10 mm long, and the 3 mm at the end of the mesh was bent at a right angle. Plastic plates, made from 0.25 mL plastic straws, were the same size and form as the metal mesh. Embryos were equilibrated with 7.5% ethylene glycol (EG) + 7.5% DMSO + 10% fetal bovine serum (FBS) in PBS for 5 min, followed by exposure to 15% EG + 15% DMSO + 0.6 M trehalose + 10% FBS in PBS for 1 min. Embryos were picked up on the metal mesh or loaded onto plastic plates with minimum volume of the solution, and then plunged into liquid nitrogen. Sample containers were placed in 1.8-mL cryotubes and stored in liquid nitrogen. Warming and dilution were performed by moving the container from liquid nitrogen into 0.5 M trehalose + 10% FBS in PBS at 37°C for 5 min. Embryos were rinsed twice in 4 mg/mL BSA + 10% FBS in NCSU37 (mNCSU37) for 5 min. Survival of the vitrified embryos was assessed after culture in mNCSU37 for 24 h (expanding blastocysts) or 48 h (morulae), and those that survived to fully expanded, hatching or hatched blastocysts were scored as viable. The vitrified warmed embryos were transferred surgically to recipient gilts. Experiment 1: The survival rates of expanding blastocysts vitrified by MMV or the control method were compared. The rate by MMV was significantly higher (84%; P < 0.01 by χ2 test) than that of the control (53%). Experiment 2: The developmental stage (morula or expanding blastocyst) suitable for vitrification was examined. Survival of expanding blastocysts was significantly higher (84%; P < 0.05) than that of morulae (55%). Experiment 3: Expanding blastocysts were vitrified by MMV, warmed, and transferred into recipients (20 embryos per recipient). Eight of 10 recipients were found to be pregnant. Seven recipients farrowed a total of 37 live and 1 stillborn piglets. The other recipient miscarried and farrowed 4 stillborn piglets. These results showed that the viability of vitrified warmed porcine embryos was affected by the material of the sample container (Experiment 1) and also by the developmental stage (Experiment 2). Since the transferred embryos showed an excellent ability to develope into piglets (Experiment 3), the MMV method developed in the present study seems to be an effective preservation method for porcine embryos.

Temperature and Dilution Effects in Soot Mass Concentration Measurements

Measurements are made of soot mass concentration in a luminous, liquid fuel spray, diffusion flame at atmospheric pressure. Intrusive sampling probes are used to study the effects of sampling rate, cooling, nitrogen-dilution ratio, and tip geometry on the mass of soot particles deposited on filters. Probe diameters have been kept small to minimize disturbance to the flow-field. Relative soot concentrations are observed to be lowest for uncooled probes, higher for water-cooled probes and still higher for probes with both water cooling and nitrogen injection. Furthermore, soot concentration steadily rises as the nitrogen/sample dilution ratio is increased from zero to as high as 1.5. Sampling rate has little effect on soot concentrations under most, but not all, sampling conditions.

System for the Determination of the Potential Degradability of Urea-Aldehyde Condensates Used as Fertilizers

A solution biodegradability system, based upon the biochemical oxygen demand principle, narrower fractionation of materials, and use of microbial cultures adapted to these individual fractions, was developed to determine potential availability. Urea-formaldehyde condensates were fractionated into five fractions: the 25°C water-soluble fraction, the fraction insoluble at 25°C but soluble at 50°C, the fraction insoluble at 50 °C but soluble at 75 °C, the fraction insoluble at 75°C but soluble at 100°C, and the fraction insoluble at 100°C. Mixed microbial cultures were developed to utilize the nitrogen in these fractions as a source of nitrogen. Degradation studies of these fractions showed that each fraction used 90—100% of the theoretical amount of nitrogen. Sample sizes as large as 0.2 g of ureaform can be used. When this system was applied to the urea-crotonaldehyde condensate used as a fertilizer, results showed that 90—105% of the nitrogen was utilizable. These biodegradability principles are useful in determining the potential degradability of any urea-aldehyde condensate showing agronomic potential.

RESIDUAL AIR DETERMINATION

A simple method is presented of revealing and calculating any "switch-over" error in the determination of the residual lung volume. Our method is shown of avoiding the possibility of error in the alveolar nitrogen sample caused by the creation of a negative pressure in a patient with a low expiratory capacity. Through the use of tables a simplified method of accurately calculating residual volumes is presented.

RESIDUAL AIR DETERMINATION

A simple method is presented of revealing and calculating any "switch-over" error in the determination of the residual lung volume. Our method is shown of avoiding the possibility of error in the alveolar nitrogen sample caused by the creation of a negative pressure in a patient with a low expiratory capacity. Through the use of tables a simplified method of accurately calculating residual volumes is presented.