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PubMedDate not supplied

Testing shelled corn for aflatoxin, Part II: modeling the observed distribution of aflatoxin test results.

The suitability of several theoretical distributions to predict the observed distribution of aflatoxin test results in shelled corn was investigated. Fifteen positively skewed theoretical distributions were each fitted to 18 empirical distributions of aflatoxin test results for shelled corn. The compound gamma distribution was selected to model aflatoxin test results for shelled corn. The method of moments technique was chosen to estimate the parameters of the compound gamma distribution. Mathematical expressions were developed to calculate the parameters of the compound gamma distribution for any lot aflatoxin concentration and test procedure. Observed acceptance probabilities were compared to operating characteristic curves predicted from the compound gamma distribution, and all 18 observed acceptance probabilities were found to lie within a 95% confidence band. The parameters of compound gamma were used to calculate the fraction of aflatoxin-contaminated kernels in contaminated lots. At 20 ppb, it was estimated that about 6 in 10,000 kernels are contaminated.

Aflatoxins↗

PubMed1975

Randomized comparative study of the copper T 300, Dalkon shield, and Shell Loop in parous women.

A randomized comparative study of the Copper T 300, the standard Dalkon Shield and the Silicone Shell Loop D was conducted on 776 parous women. Net cumulative first event rates at 1 year and at 18 months, calculated by life-table analysis, were as follows: Copper T 300--pregnancy 1.2/1.9, expulsion 6.4/7.0, removal for pain or bleeding 7.4/10.8; Dalkon Shield--pregnancy 2.7/4.5, expulsion 5.8/5.8, removal for pain or bleeding 7.7/14.7; Shell Loop--pregnancy 3.8/4.9, expulsion 0.5/0.5, removal for pain or bleeding 9.1/13.1. None of the differences in event rates, except the lower expulsion rate of the Shell Loop, were significant. The continuation rates for the three devices at both 12 and 18 months were similar, indicating that there was little difference in their performance. As the results of this study showed a similarity of the incidence of events among very differently disigned IUD's, previously reported differences in performance of these and possibly other types of IUD's may very likely be more related to differences among clinics than to differences among the devices themselves.

Adolescent↗

PubMed2001

[Raman spectra of nacre from shells of main pearl-culturing mollusk in China].

The Raman spectra of nacre and cultured pearl from main pearl-culturing mollusks in China have been studied systematically in this paper. It shows that: 1) the Raman bands caused by organic matrix have not been observed in nacre from shell of pinctada maxima; 2) in nacre from shell of pinctada martensii and hyriopsis cumingii, besides the bands caused by aragonite mineral, two bands resulted from all-trans carotenoid are obviously observed, and the number of C=C double bonds in molecular of this carotenoid is predicted to be 10 based on the position of its Raman bands; 3) a number of complicated bands are observed in nacre from shell of peteria penguin, and we predicted that this bands perhaps are caused by metalloporphyrin compounds; 4) the relative concentrations of carotenoid and metalloporphyrin in nacre are closely associated with the color of nacre. The Raman spectra research on organic matrix in nacre and cultured pearl provides insight into the applications of them in cosmetics and food, as well as in application of pearl bleaching.

Animals↗

PubMedDate not supplied

[Evaluation of the effect of the dilution of urine on the toxicity and isolation of cytomegalovirus using the rapid shell-vial centrifugation culture technique].

Working with highly passaged MRC-5 fibroblast monolayers in a shell-vial culture-centrifugation assay for rapid detection of cytomegalovirus (CMV), a direct toxic effect of the urine on the monolayer was observed in as many as 44% of cases when vials were inoculated with undiluted specimens. This toxicity was reduced to only 6% by inoculation of shell-vials with samples diluted 1:1 with viral transport medium. The recovery of CMV in shell-vials was not significantly affected by the dilution factor, since five cases detected in conventional culture in tubes and not in vials were compensated by seven cases detected in vials and not in tubes.

Artifacts↗

PubMedDate not supplied

[The use of the shell of the cashew nut, Anacardium occidentale, as an alternative molluscacide].

Bioassays using hexanolic extracts of cashew nut shells, of Anacardium occidentale, collected in Ceará in 1972 (Sample 1) and 1987 (Sample 2) were undertaken with adult snails and egg masses of Biomphalaria glabrata, B. tenagophila and B. straminea both in the laboratory and in the field. Non extracted shells, 18.5 g, sample 1, were also tested with adult snails and egg masses of the three species. The toxicity of extract was tested with fish (Poecilia reticulata) and tadpoles. The lethal concentration, CL90, of sample 1 was from 2.0 to 2.2 ppm for adult snails of the three species. With sample 2, the CL90 was 2.0, 0.5 and 30.0 ppm for B. glabrata adults, newly hatched snails and egg mass respectively. Non extracted shells caused 40-80% mortality of adult snails, 22-35% mortality of embryos and 40-55% reduction of egg production. The hexanolic extract, sample 2, were innocuous for tadpole and fish at 2 ppm. In the field, in pools of still water treatment with 20 ppm of extract, sample 1, caused a 97.1% mortality of B. straminea and 100% mortality of B. glabrata and B. tenagophila. Using Niclosamide, at 3 ppm, 100% mortality of the three species occurred.

Animals↗

PubMed2003

Photosensitivity in feedlot calves apparently related to cocoa shells.

Primary photosensitization was observed in 11/78 cross-breed calves. The skin lesions were diffuse dermatitis with thickening and wrinkling with areas of alopecia. The severe photosensitivity dermatitis was associated with cocoa shell ingestion. The lesions resolved after removal of the cocoa shells from the feed ration and prevention of exposure to sunlight. Cocoa shells may contain photodynamic agents that cause photosensitization in calves.

Animal Feed↗

PubMed2003

On the use of crushed shells of apricot stones as the upper layer in dual media filters.

The use of crushed shells of apricot stones instead of anthracite coal in dual-media filters is investigated. Turbidity removal efficiencies were measured for several filtration rates in dual media filters composed of shells of apricot stones above silica sand and anthracite coal above silica sand. Backwash (fluidization) experiments were carried out using sieved fractions of crushed shells of apricot stones to establish curves of expansion versus backwash velocity at 25 degrees C. Such curves can be used in the design of filters employing this material. It is believed that the use of such a locally available and cheaper alternative filter medium would be of interest in many small water and wastewater treatment systems around the world.

Biodegradation, Environmental↗

PubMed2004

Investigation of the effects of microbubble shell disruption on population scattering and implications for modeling contrast agent behavior.

In a previous study, quantitative measurement of nonlinear scattering revealed some quantitative discrepancies with a model for ultrasound scattering by a population ensemble of microbubbles. This study is designed to investigate the effect of the shell on single-pulse scattering by a population of contrast microbubbles. Nonlinear scattering was measured shortly (15 micros) after exposure to a previous ultrasound pulse with variable intensity. The short time delay eliminated the influence of gas diffusion and focused the study on the consequence of ultrasound exposure. The results suggest that single-pulse scattering is dependent on the disruption properties of the bubble shell and confirm the significance of the shell properties.

Contrast Media↗

PubMed2004

Synthesis and crystallization of hybrid spherical colloids composed of polystyrene cores and silica shells.

The Stöber method has been adopted to prepare hybrid core-shell particles by coating the surfaces of monodisperse polystyrene beads with uniform silica shells. Polystyrene beads with diameters in the range of 0.1-1.0 microm have been successfully demonstrated for use with this process, and the thickness of the silica coating could be controlled in the range of 50-150 nm by adjusting the concentration of tetraethoxysilane, the deposition time, or both. The morphology and surface smoothness of the deposited silica were found to strongly depend on a number of parameters such as the surface functional groups on the polymer beads, the pH value of the medium, and the deposition time. Hollow spheres made of silica could be obtained by selectively removing the polymer cores via calcination in air at an elevated temperature or by wet etching with toluene. These core-shell colloids were also explored as building blocks to fabricate long-range ordered lattices (or colloidal crystals) that exhibited stop bands different from those assembled from spherical colloids purely made of either polystyrene or silica.

Journal Article↗

PubMedDate not supplied

A thin-shell model of the cornea and its application to corneal surgery.

BACKGROUND: We present a thin-shell, analytical model of the vertebrate cornea to study the changes in shape resulting from surgical operations (eg, radial keratotomy). METHODS: A simple closed-form solution is derived for a thin linearly elastic spherical model of the cornea. We assume that the shell is symmetrical about a central axis and that the modulus of elasticity is the same in all directions. The surgery is modeled by allowing the modulus of elasticity (or equivalently the thickness) of the shell to depend upon position, measured as an angle from the axis of symmetry. RESULTS: The analytical nature of the solution allows us to compute the principal curvatures of the cornea explicitly. For example, for representative parameters, the model predicts the average corneal curvature changes from about 43 diopters before keratotomy to about 38 D after keratotomy. CONCLUSIONS: The model is used to estimate Young's modulus from experimental data reported previously by Thomas et al (Invest Ophthalmol Vis Sci 1991;32:1000), as well as to investigate the effect of surgery on corneal flattening and the associated sensitivity to intraocular pressure changes.

Biomechanical Phenomena↗

PubMedDate not supplied

Effect of pine seed shell extract on microbial and viral infection.

Pretreatment of mice with ammonia extract of seed shell of Pinus Koraicenis, via the intraperitoneal or intravenous route, effectively protected them from lethal infection of Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. The pine seed shell extract also moderately inhibited syncytium formation and cytopathogenic effect induced by human immunodeficiency virus (HIV) infection in cultured human lymphotropic virus type I (HTLV-1) positive MT-4 cells. These data suggest a medicinal potential of pine seed shell extract against opportunistic infection in HIV patients.

Animals↗

PubMed1992

On the mechanism of penetration of ovicidal fungi through egg-shells of parasitic nematodes. Decomposition of chitinous and ascaroside layers.

The decomposition of egg-shells of Ascaris lumbricoides L. was studied microscopically using topochemical methods in a set of 32 strains of soil ovicidal fungi. It was found that even fungi displaying minimal chitinolytic activity in tests on purified chitin in vitro are able to dissolve chitin of egg-shells during the attack on live eggs. Fungi without any chitinolytic activity penetrate probably only the mechanically damaged eggs. None of the studied fungi was capable of degrading enzymatically the glycolipid (ascaroside) layer of the egg-shell which remained intact after digestion of all other components of the egg.

Animals↗

PubMedDate not supplied

Predicting aflatoxin and fumonisin in shelled corn lots using poor-quality grade components.

A study was conducted to determine if aflatoxin and fumonisin are concentrated in the poor-quality grade components of shelled corn. Four 1.0 kg test samples were each taken from 23 lots of shelled corn marketed in North Carolina. Inspectors from the Federal Grain Inspection Service divided each test sample into 3 grade components: (1) damaged kernels (DM), (2) broken corn and foreign material (BCFM), and )3) whole kernels (WH). The aflatoxin and fumonisin concentration was measured in each component and a mass balance equation was used to calculate the total concentration of each mycotoxin in each test sample. Averaged across all test samples, the aflatoxin concentrations in the DM, BCFM, and WH components were 1300.3, 455.2, and 37.3 ppb, respectively. Averaged across all test samples, the fumonisin concentrations in the DM, BCFM, and WH components were 148.3, 51.3, and 1.8 ppm, respectively. The DM and BCFM components combined accounted for only 5.0% of the test sample mass, but accounted for 59.8 and 77.5% of the total aflatoxin and fumonisin mass in the test sample, respectively. Both aflatoxin mass (ng) and aflatoxin concentration (ng/g) in the combined DM and BCFM components had high correlations with aflatoxin concentration in the lot. The highest correlation occurred when aflatoxin mass (ng) in the combined DM and BCFM components was related to aflatoxin concentration in the lot (0.964). Similar results were obtained for fumonisin. This study indicated that measuring either aflatoxin or fumonisin in the combined DM and BCFM grade components could be used as a screening method to predict either aflatoxin or fumonisin in a bulk lot of shelled corn.

Aflatoxins↗

PubMed2006

Microgeographic evolution of snail shell shape and predator behavior.

Genetic divergence in geographically isolated populations is a prerequisite for allopatric speciation, one of the most common modes of speciation. In ecologically equivalent populations existing within a small, environmentally homogeneous area, an important role for environmentally neutral divergence is often found or inferred. We studied a species complex of conspicuously shaped Opisthostoma land snails on scattered limestone outcrops within a small area of lowland rainforest in Borneo. We used shell morphometrics, mitochondrial and nuclear DNA sequences, and marks of predation to study the factors involved in allopatric divergence. We found that a striking geographic divergence exists in shell morphology, which is partly associated with neutral genetic divergence. We also found geographic differentiation in the behavior of the snails' invertebrate predator and evidence of an evolutionary interaction between aspects of shell shape and predator behavior. Our study shows that adaptation to biotic aspects of the environment may play a more important role in allopatric speciation than previously suspected, even on a geographically very small scale.

Adaptation, Physiological↗

PubMed1991

[Detection of cytomegalovirus in urine by the shell-vial technique: usefulness of diluting the sample].

To assess the toxicity of urine samples on human fibroblast cell monolayer using Shell-vial technique for cytomegalovirus antigen detection. A total of 227 urine samples were processed, inoculated on Shell-vial simultaneously, being either diluted (1:1) and non diluted in transport media. After 24-48 hours incubation, the fibroblast cells monolayer was stained using fluorescein-marked monoclonal anti-cytomegalovirus antibodies. Cytomegalovirus was detected in 9.6% of samples inoculated with diluted urine, and in 5.2% of samples inoculated with non-diluted urine. Destruction of monolayer cells was seen in 13.2 and 22.4, respectively. With Shell-vial technique for detecting cytomegalovirus in urine samples, a high number of positive results was obtained using diluted urine. Also a significant minor destruction of cells monolayer was observed with the same inoculum.

Antibodies, Monoclonal↗

PubMed1991

[Stereotactic irradiation using a linear accelerator with helmet-type shell].

A new method is proposed for external stereotactic and three-dimensional irradiation for a small target in the skull. In this method, we use a special long tube collimator, helmet-type shell (guiding rods are attached to the shell using the CT-stereotactic apparatus) and 10 MV linear accelerator. The patient's head is fixed conservatively by the helmet-type shell. In the phantom experiment, the 90% isodose area was 10 mm in diameter, and the error between the geometrical center of the target and the irradiated center was 2 mm.

Brain Neoplasms↗

PubMed1990

Visualization of chitin-protein layer formation in Ascaris lumbricoides egg-shells.

The formation of chitin-protein layer in Ascaris lumbricoides egg-shells was studied using the method of chitin structures visualization by means of derivatives of stilbene-disulfonic acid (Blankophor, Bayer, FRG). Intensive formation of chitin structures in A. lumbricoides egg-shell occurred only in fertilized females in a very short portion of uterus from the site of connection of the oviduct with the uterus up to 25-30 mm distally, i.e. in the section forming about one fifth or less than one sixth of length of adult female uterus. Already 3 mm from the beginning of uterus there was a thin layer on the surface of the fertilized eggs which contained chitin detectable by Blankophor visualization, whereas the chitin-protein layer on the shells could not be demonstrated histologically. The thickness of this chitin-protein complex increased distally. At 25 mm from the beginning of uterus the chitin layer was already complete and its thickness did not increase any more.

Animals↗

PubMed1987

Penetration of ovicidal fungus Verticillium chlamydosporium through the Ascaris lumbricoides egg-shells.

The course of penetration of the ovicidal fungus Verticillium chlamydosporium Goddard through the Ascaris lumbricoides egg-shells was studied in electron miorographs. The contact area between the egg and the fungus is smooth at the stage of the contact of the ovicidal fungus with the egg surface, as well as at the stage of adhesion. No special attaching organs are formed which indicates that no mechanical penetration of the fungal hypha through the egg-shells is involved. Traces of enzymatical activity of the fungus penetrating upright through the egg-shells can be observed during the penetration stage proper. At the consumption stage, the branching of the ovicidal fungus becomes more dense and some hyphae grow through the egg envelopes parallelly under the egg surface. The fungus grows through all parts of the infected egg, even through its contents.

Animals↗