Several methods are used to generate a limit of detection for organic pollutants measured by gas chromatography-mass spectroscopy (GC-MS); all have theoretical and practical drawbacks. The current ...project investigated two common existing methods (statistical and empirical) for applicability to chromatographic properties from real samples, comparing these with a new proposed method using procedural blanks to estimate a minimum detectable peak area. Weaknesses of all three methods are discussed. The proposed method was superior to other examined methods in that it provided analyte-specific limits of detection linked to the recovery of mass-labeled internal standards for every analyte within every sample. Other identified quality assurance benefits included the following: enhanced protection against false positives; providing a sensitivity performance metric across batch, analyst, and instrument; enabling chemists with discretionary decisions specific to every analyte regarding detectability and interferences; and some strengths of both statistical and empirical techniques without major drawbacks of either. In marine sediment samples, the proposed method of calculating the limit of detection increased reporting of trace level (low- to subppb) GC-MS data for polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), and polycyclic aromatic hydrocarbons (PAHs) by up to 400% compared with the statistical method.
Polychlorinated biphenyl congeners were measured in 520 composite fish tissue samples collected from Maryland between 1999 and 2004. Thirty-six species were sampled from 190 sites. PCB concentrations ...in fish tissues were compared across taxa, regions and to Maryland fish consumption advisory levels. A multivariate analysis of PCB congeners in 126 white perch and 94 channel catfish from diverse locations was used to investigate patterns of PCB transport. The greatest PCB concentrations were measured in channel catfish from the Patapsco (1770 ng/g wet) and Potomac Rivers (1770 ng/g wet), the northern Chesapeake Bay (1000 ng/g wet), the Chesapeake and Delaware Canal (850 ng/g wet), and in carp from Back River (1400 ng/g wet). PCB congener patterns varied spatially and reflected local PCB sources. Congener signatures were used to map the contamination associated with each PCB source region. Apparent congener transport distances correlated positively with hydrophobicity and negatively with volatility.
Pork quality characteristics related to the dietary substitution of soybean meal by the micro-alga Spirulina (Arthrospira platensis) or black soldier fly (Hermetia illucens) partly-defatted larval ...meal were observed. Through a duplicated study totalling 48 individually-fed barrows (Pietrain × (Large White × Landrace)) allocated into two experimental groups and a control, the effect of dietary protein source on physico-chemical and sensory pork quality was monitored under current industrial packaging conditions (highly‑oxygenated modified atmosphere packaging). The results show that physico-chemical characteristics are not degraded by including alternative protein sources in pig diets. Hermetia illucens increased lauric acid levels in backfat indicating that this fatty acid may be suitable as a biomarker for Hermetia illucens-fed pork. This goes to show that protein alternatives do not compromise pork quality.
The human microbiome is intimately associated with human health, with a role in obesity, metabolic diseases such as type 2 diabetes, and divergent diseases such as cardiovascular and ...neurodegenerative diseases. The microbiome can be changed by diet, probiotics, and faecal transplants, which has flow-on effects to health outcomes. Photobiomodulation has a therapeutic effect on inflammation and neurological disorders (amongst others) and has been reported to influence metabolic disorders and obesity. The aim of this study was to examine the possibility that PBM could influence the microbiome of mice. Mice had their abdomen irradiated with red (660 nm) or infrared (808 nm) low-level laser, either as single or multiple doses, over a 2-week period. Genomic DNA extracted from faecal pellets was pyrosequenced for the 16S rRNA gene. There was a significant (
p
< 0.05) difference in microbial diversity between PBM- and sham-treated mice. One genus of bacterium (
Allobaculum
) significantly increased (
p
< 0.001) after infrared (but not red light) PBM by day 14. Despite being a preliminary trial with small experimental numbers, we have demonstrated for the first time that PBM can alter microbiome diversity in healthy mice and increase numbers of
Allobaculum
, a bacterium associated with a healthy microbiome. This change is most probably a result of PBMt affecting the host, which in turn influenced the microbiome. If this is confirmed in humans, the possibility exists for PBMt to be used as an adjunct therapy in treatment of obesity and other lifestyle-related disorders, as well as cardiovascular and neurodegenerative diseases. The clinical implications of altering the microbiome using PBM warrants further investigation.
We present a catalog of 9316 spectroscopically confirmed white dwarfs from the Sloan Digital Sky Survey Data Release 4. We have selected the stars through photometric cuts and spectroscopic modeling, ...backed up by a set of visual inspections. About 6000 of the stars are new discoveries, roughly doubling the number of spectroscopically confirmed white dwarfs. We analyze the stars by performing temperature and surface gravity fits to grids of pure hydrogen and helium atmospheres. Among the rare outliers are a set of presumed helium-core DA white dwarfs with estimated masses below 0.3 M sub( ), including two candidates that may be the lowest-mass yet found. We also present a list of 928 hot subdwarfs.
PDF