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Effect during Entrepreneurial Process Focusing on Opportunity Development and Entrepreneurial ProcessDeenissai, Wanussavee January 2010 (has links)
No description available.
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Label free biosensing with carbon nanotube transistorsLeyden, Matthew R. 10 June 2011 (has links)
As electronics reach nanometer size scales, new avenues of integrating biology and electronics become available. For example, nanoscale field-effect transistors have been integrated with single neurons to detect neural activity. Researchers have also used nanoscale materials to build electronic ears and noses. Another exciting development is the use of nanoscale biosensors for the point-of-care detection of disease biomarkers.
This thesis addresses many issues that are relevant for electrical sensing applications in biological environments. As an experimental platform we have used carbon nanotube field-effect transistors for the detection of biological proteins. Using this experimental platform we have probed many of properties that control sensor function, such as surface potentials, the response of field effect transistors to absorbed material, and the mass transport of proteins. Field effect transistor biosensors are a topic of active research, and were first demonstrated in 1962. Despite decades of research, the mass transport of proteins onto a sensor surface has not been quantified experimentally, and theoretical modeling has not been reconciled with some notable experiments. Protein transport is an important issue because signals from low analyte concentrations can take hours to develop. Guided by mass transport modeling we modified our sensors to demonstrate a 2.5 fold improvement in sensor response time. It is easy to imagine a 25 fold improvement in sensor response time using more advanced existing fabrication techniques. This improvement would allow for the detection of low concentrations of analyte on the order of minutes instead of hours, and will open the door point-of-care biosensors. / Graduation date: 2011
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1373 |
The effect of cultivar maturity and frozen storage time on the cell wall polysaccharide composition of muskmelon(Cucumis melo)Simandjuntak, Valencius 08 July 1993 (has links)
The effect of frozen storage time on the composition
of the cell wall polysaccharide (CWP) of muskmelon (Cucumis
melo) cultivars at different stages of maturity was investigated.
Changes in composition, firmness, drip loss, and
color of Cantaloupe and Honey Dew melon flesh were determined
at three stages of maturity and for three periods of
storage at -23°C. Relationships between firmness, drip
loss, and other composition measurements, as well as the
total CWP sugar composition, were also determined.
Cell wall polyssacharides were isolated and purified,
and fractionations were performed using cyclohexane trans-
1,2-diamine tetraacetate (CDTA), Na₂C0₃, guanidinium thiocyanate
(GTC), and KOH. All fractions and residues were
dialysed and then freeze-dried. Following hydrolysis of
CWP fractions with trifluoroacetate (TFA), the alditol acetate derivatives of neutral sugars from each CWP fraction
were prepared and analyzed by gas chromatography,
using myo-inositol as the internal standard.
TFA insoluble fractions were analyzed colorimetrically
using phenol-sulphuric acid reagent. Uronic acid was determined
using 0.15% m-hydroxybiphenyl for absorbance at
520 nm with galacturonic acid as the standard. It was determined
that CDTA and Na₂C0₃ fractions were composed of
typical pectic materials, containing mostly galacturonic
acid with the neutral sugars arabinose, galactose, rhamnose,
and a smaller amount of xylose. As maturity increased,
CDTA fraction yields increased, though total neutral
sugar CWP compositions decreased. GTC and KOH fractions
were typical of hemicellulose, and contained principally
xylose, glucose, galactose, mannose, and fucose, with very
small amounts of uronic acid, arabinose, and rhamnose.
Residue fractions contained principally glucose and galactose,
with smaller amounts of mannose, xylose, arabinose,
and fucose. With the exception of xylose and glucose, all
neutral sugars decreased significantly (p < 0.01) as maturity
increased in both the Cantaloupe and Honey Dew melons.
Total uronic acid did not change as maturity increased,
except for Cantaloupe, where total uronic acid decreased
from the ripe to overripe stages. The CDTA fraction
yield increased and all neutral sugars decreased
significantly (p < 0.05) as storage time was increased.
Only the CDTA fraction yield was negatively correlated with the firmness of both melons, and was positively correlated
with drip loss as maturity and frozen storage time were increased.
Firmness was positively correlated with Na₂C0₃ and
GTC fraction yield in Cantaloupe, whereas for Honey Dew
there was no correlation between firmness and Na₂C0₃ or GTC
fraction yield as maturity increased. The KOH fraction was
negatively correlated with firmness in Cantaloupe, whereas
there was no correlation between firmness and KOH fractions
in Honey Dew existed as maturity increased. The residue
fractions increased in both melons only from the underripe
to the ripe stages, and did not change from ripe to overripe.
Firmness was positively correlated with total rhamnose,
arabinose, mannose, and galactose as maturity increased,
and the drip loss was negatively correlated with
all total neutral sugars as storage time was increased.
During frozen storage, there was a significant decreases
(p < 0.05) in total CWP sugars in relation to increased
storage time. The decrease in total sugars was
more dramatic during the 0 to 5 month period than the 5 to
10 month period of frozen storage. Galactose did not
change in the Cantaloupe, whereas in Honey Dew it decreased
34.3% from 0 to 5 months then decreased only 13% from 5 to
10 months of storage. / Graduation date: 1994
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1374 |
Influence of ethanol on copper utilization by pregnant and growing ratsAstell, Rebecca L. 06 December 1988 (has links)
Pregnant and weanling rats were fed liquid diets with
or without 30 percent of total kcal from ethanol and varying
levels of copper in order to determine if ethanol ingestion would
exaggerate a marginal copper status to an obvious copper
deficiency. Pregnant albino rats were fed either 0.75 or 3.75 mg
Cu/L throughout gestation and the first 15 days of lactation while
female weanling rats received 0.5 or 2.5 mg Cu/L for 5 weeks.
Ethanol consumption exaggerated a marginal copper status during
reproduction as evidenced by significant reductions in maternal
liver copper concentration and enzymatic activity of the copper
metalloprotein Copper-Zinc superoxide dismutase in offspring
liver. Ethanol had little or no effect upon copper status in
weanling rats. In addition, serum copper failed to reflect a
developing depletion of liver copper when ethanol was being consumed. Since it is known that the average American diet is
just adequate in copper content, and that copper balance is
difficult to achieve during times of increased metabolic demand,
pregnant subjects may be at a great risk to develop a copper
deficiency when ethanol is being consumed. This ethanol and
copper interaction, however, will likely go undetected if only
serum copper is used as an indicator of copper status. / Graduation date: 1989
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Radiation pasteurization of raw and chlortetracycline-treated shrimpAwad, Ahmed Ali 28 January 1963 (has links)
Pasteurization radiation offers a new means of extending the
refrigerated storage life of foods. This procedure avoids many of
the undesirable changes which result when sterilization radiation is
used and still eliminates most of the spoilage organisms.
Shrimp was treated with 5 ppm chlortetracycline and subjected
to pasteurization levels of gamma radiation and stored at 38°F. The
levels of irradiation used were 0.5 and 0.75 megarad. These levels
were based on the flavor threshold of irradiation intensity.
The quality of the stored irradiated shrimp was determined by
subjective evaluation, chemical analyses and microbiological examinations.
The storage life of the shrimp irradiated at 0.5 megarad was
extended to 5 weeks, compared with 1 week for the unirradiated
samples held at the same temperature. Throughout the ten week
storage period, the samples which received doses of 0.5 megarad and CTC and those which received 0.75 megarad with and without
CTC remained in good condition. / Graduation date: 1963
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1376 |
Ecology and decline of a rare western minnow : the Oregon chub (Oregonichthys crameri)Pearsons, Todd N. 17 January 1989 (has links)
Once historically widespread throughout the Willamette and Umpqua
River drainages, the Willamette Oregon chub is now restricted to
scattered populations along 15 miles of the Middle Fork of the
Willamette River whereas the Umpqua Oregon chub is still widely
distributed. The decline in the Willamette drainage was more severe
because changes in the physical and biological habitat were more severe
when compared to the Umpqua drainage. The Willamette Oregon chub may
be more sensitive to environmental degradations than the Umpqua Oregon
chub. The difference in sensitivity to degradation is a result of
ecological differences between Willamette and Umpqua Oregon chub.
Willamette Oregon chub inhabited areas with primarily very little if
any current, fed in the water column, and spawned in aquatic
vegetation. Umpqua Oregon chub inhabited areas with primarily slow
water velocities, fed on benthic prey, and spawned over gravel substrate. Because Willamette Oregon chub inhabit slackwater habitats
they may be more sensitive to water velocity increases and exotic
species, whereas Umpqua Oregon chub have a habitat refuge in relatively
faster water velocity habitats.
Willamette Oregon chub larval stages are described and
illustrated. The following combination of characters distinguish
Willamette Oregon chub larvae from other cyprinid larvae found in the
Willamette drainage: 33-37 myomeres, preanal length of 52-61%, and
absence of snout pigment. Willamette Oregon chub larvae generally
congregated in nearshore areas, in the upper layers of the water
column, in shallow water. They fed primarily in the water column, and
ate primarily rotifers and cladocerans. / Graduation date: 1989
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1377 |
Optimisation of submicron low-noise GaAs MESFETsAhmed, Muhammad Mansoor January 1995 (has links)
No description available.
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1378 |
Measurements of Landau quantum oscillations in heavy fermion systemsHill, Robert W. January 1996 (has links)
No description available.
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1379 |
Digital signal processing techniques for speech enhancement in hearing aidsCanagarajah, Cedric Nishanthan January 1993 (has links)
No description available.
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1380 |
PHOTOPERIODIC REGULATION OF THE FEMALE REPRODUCTIVE SYSTEM IN THE SYRIAN HAMSTER (OVARY, PINEAL, HORMONES, PITUITARY).HAUSER, URSULA ESTHER. January 1986 (has links)
Female golden Syrian hamsters are seasonally breeding animals, capable of maintaining continuous estrous cycles when the daylength is 12.5 hrs. or longer. In shorter photoperiod (SP) the ovaries of anovulatory animals are characterized by few small growing follicles, an absence of corpora lutea and extensive hypertrophied interstitium. Steroid-histochemical studies revealed that enzymes related to steroidogenesis show intense activity in the interstitial tissue of SP-exposed animals. The major objectives of these studies were to examine SP-induced hormonal and ovarian changes which occur prior to onset of the acyclic condition in inbred LSH/SsLak hamsters. Other experiments explored hormonal changes in the absence of ovarian hormones and the interaction of SP and steroids. Initial results revealed that the LSH/SsLak hamster ceased estrous cyclicity between 14 and 31 days of SP exposure, a response far more uniform than generally seen in outbred hamsters. Experiments carried out in SP-exposed cyclic animals indicated that the secondary FSH surge and follicular recruitment were not affected by SP treatment, follicular recruitment were not affected by SP treatment, and that no major changes in gonadotropin levels and ovarian steroids were present on individual days of the estrous cycle. Once the animals were anestrous, daily gonadotropin surges were present and pituitary gonadotropin contents increases. Serum PRL levels showed a slight, yet significant, decrease in SP cycling animals followed by a further reduction in pituitary and serum levels after animals ceased cycling. Medial basal hypothalamic LHRH contents did change in SP, yet there was a significant increase in the preoptic area, and LHRH became significantly elevated in both areas after the animals became anestrous. Ovarian histology revealed fewer corpora lutea and a slight shift from healthy to atretic antral follicles. Experiments carried out in ovariectomized SP-treated animals showed that serum gonadotropin levels were significantly reduced, and that estrogen treatment was either equally or less effective in reducing levels in SP animals. In contrast, PRL levels did not change and responded in a dose dependent way to estrogen treatment. Although the studies yielded no definite proof, the result suggest that SP impairs the maintenance of follicular growth leading eventually to the acyclic state.
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