138 research outputs found
Partition Column Chromatography for Quantitating Effects of Fertilization on Plant Acids
A method for determining organic acid levels in
biological materials by silica gel partition column
chromatography (pcc) is described. It uses tetrabromophenolphthalein
ethyl ester, which has a
high molar absorbency, for quantitating the acids
in the column effluent. The concentrations of
several organic acids were determined in two
species of crested wheatgrass, Nordan (Agropyron
desertorum) and Fairway (A. cristatum), grown.
under different conditions of K fertilization. For
comparison, aconitic, citric, and malic acids were
also determined by polarography, spectrophotometry,
and fluorometry, respectively. Results obtained
by these methods agreed with the data obtained
by pcc. The concentration of trans-aconitic
acid averaged about 96 and 21 mequiv/kg of
dry matter in Nordan and Fairway, respectively,
when grown in the greenhouse without K. K fertilization
(312 kg/ha) approximately doubled the
trans-aconitic acid concentration in both species.
Fairway contained 363 mequiv/kg of malic acid,
while Nordan contained 280 mequiv/kg. K fertilization
increased these concentrations to 611 and
446 mequiv/kg, respectively. Citric acid was increased
by K fertilization, but there was no significant
difference between species and in no case
was the citric acid concentration greater than 80
mequiv/kg of dry matter
Effects of red grape, wild grape and black raspberry wines on ground pork during refrigerated storage
The effects of red grape, wild grape and black raspberry wines on the quality of ground pork during a 15 days refrigerated storage period were investigated. The levels of phenolic compounds were the highest in black raspberry wine (P0.05). The addition of 5% and 10% wine influenced the quality of ground pork by decreasing pH, inhibiting the progression of lipid oxidation and the formation of total volatile basic nitrogen (TVB-N), and stabilizing the red colour of the ground pork compared to control samples to which no wine was added. In ground pork, addition of red grape wine led to lower concentrations of thiobarbituric acid reactive substances (TBARS, 0.19–0.39 mg kg−1) and TVB-N values (69.1–119.9 mg kg−1) than wild grape (0.16–0.43 mg kg−1 and 72.0–194.1 mg kg−1, respectively) or black raspberry wine (0.33–0.58 mg kg−1 and 81.7–225.4 mg kg−1, respectively) up to 10 days of storage. Results from the present study suggested that the quality of ground pork was affected by wine type and storage period. These effects could be due to phenolic compounds as well as other chemical components of the wines
Astroparticle Physics with a Customized Low-Background Broad Energy Germanium Detector
The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg
array of high purity germanium detectors housed in an ultra-low background
shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA
DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while
demonstrating the feasibility of a tonne-scale experiment. It may also carry
out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that
customized Broad Energy Germanium (BEGe) detectors produced by Canberra have
several desirable features for a neutrinoless double-beta decay experiment,
including low electronic noise, excellent pulse shape analysis capabilities,
and simple fabrication. We have deployed a customized BEGe, the MAJORANA
Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and
shield at the Kimballton Underground Research Facility in Virginia. This paper
will focus on the detector characteristics and measurements that can be
performed with such a radiation detector in a low-background environment.Comment: Submitted to NIMA Proceedings, SORMA XII. 9 pages, 4 figure
Comparison of the antioxidant potential of antiparkinsonian drugs in different in vitro models
Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta. Furthermore, oxidative stress plays a role in PD, causing or contributing to the neurodegenerative process. Currently PD has only symptomatic treatment and still nothing can be done to stop the degenerative process of the disease. This study aimed to comparatively evaluate the antioxidant capacity of pramipexole, selegeline and amantadine in different in vitrostudies and to offer possible explanations on the molecular antioxidant mechanisms of these drugs. In vitro, the antioxidant capacity of the drugs was assessed by the ability of antiparkinsonian drugs to decrease or scavenge ROS in the neutrophil respiratory burst, ability of antiparkinsonian drugs to donate hydrogen and stabilize the free radical 2,2-diphenyl-1-picryl-hydrazyl (DPPH•), to scavenge 2,2'-azino-di-(3-ethylbenzthiazoline-6-sulphonic acid (ABTS+) and evaluation of the ferric reducing antioxidant power (FRAP). This study demonstrated that both pramipexole and selegiline, but not amantadine, have antioxidant effects in vitro by scavenging superoxide anion on the respiratory burst, donating electron in the ABTS+ assay and presenting ferric reduction antioxidant power. This chemical structure-related antioxidant capacity suggests a possible neuroprotective mechanism of these drugs beyond their already recognized mechanism of action
The MAJORANA experiment: An ultra-low background search for neutrinoless double-beta decay
The observation of neutrinoless double-beta decay would resolve the Majorana nature of the neutrino and could provide information on the absolute scale of the neutrino mass. The initial phase of the MAJORANA experiment, known as the DEMONSTRATOR, will house 40 kg of Ge in an ultra-low background shielded environment at the 4850' level of the Sanford Underground Laboratory in Lead, SD. The objective of the DEMONSTRATOR is to determine whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a narrow region of interest around the 76Ge neutrinoless double-beta decay peak
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