The effect of electrolytes on the viscosity and time of set of silicic acid gels

This thesis contains the results of experiments of the effects of electrolysis of the viscosity and time of set of silicic acid gels

Ampliación de las operaciones de mercado abierto en Colombia

El establecimiento de un mercado abierto representa un desarrollo normal del sistema financiero colombiano, ya sea que se realice dentro del marco existente o que se incorpore dentro de una reforma monetaria integral. Los banqueros y financistas apoyan la institucionalización del mercado extrabancario y además existe un consenso casi general sobre la necesidad de reformar sustancialmente el sistema financiero

Mechanisms of Toxin Resistance by Wild Mammalian Herbivores

Some wild vertebrate herbivores are able to ingest potentially toxic plants. However, the mechanisms that facilitate toxin tolerance are relatively unknown in free-ranging vertebrate herbivores. We hypothesized that one mechanism of toxin tolerance is regulated absorption of ingested toxins resulting in excretion of unchanged toxins in feces and low blood exposure to toxins. We tested this hypothesis using free-ranging moose (Alces americanus) in Isle Royale National Park in Lake Superior, Michigan. These moose consume large amounts of balsam fir (Abies balsamea) that contains high concentrations of plant secondary metabolites (PSM), which are toxic to most herbivores. To assess regulated absorption, we measured concentrations of unchanged monoterpenes in fecal samples of moose and in paired samples of balsam fir using gas chromatography. Understanding the mechanisms of how herbivores regulate and tolerate toxins may offer vital information that could lead to predicting and managing drug tolerance in humans, pest species, and bacteria

Improved Underwater Excitation-Emission Matrix Fluorometer

A compact, high-resolution, two-dimensional excitation-emission matrix fluorometer (EEMF) has been designed and built specifically for use in identifying and measuring the concentrations of organic compounds, including polluting hydrocarbons, in natural underwater settings. Heretofore, most EEMFs have been designed and built for installation in laboratories, where they are used to analyze the contents of samples collected in the field and brought to the laboratories. Because the present EEMF can be operated in the field, it is better suited to measurement of spatially and temporally varying concentrations of substances of interest. In excitation-emission matrix (EEM) fluorometry, fluorescence is excited by irradiating a sample at one or more wavelengths, and the fluorescent emission from the sample is measured at multiple wavelengths. When excitation is provided at only one wavelength, the technique is termed one-dimensional (1D) EEM fluorometry because the resulting matrix of fluorescence emission data (the EEM) contains only one row or column. When excitation is provided at multiple wavelengths, the technique is termed two-dimensional (2D) EEM fluorometry because the resulting EEM contains multiple rows and columns. EEM fluorometry - especially the 2D variety - is well established as a means of simultaneously detecting numerous dissolved and particulate compounds in water. Each compound or pool of compounds has a unique spectral fluorescence signature, and each EEM is rich in information content, in that it can contain multiple fluorescence signatures. By use of deconvolution and/or other mixture-analyses techniques, it is often possible to isolate the spectral signature of compounds of interest, even when their fluorescence spectra overlap. What distinguishes the present 2D EEMF over prior laboratory-type 2D EEMFs are several improvements in packaging (including a sealed housing) and other aspects of design that render it suitable for use in natural underwater settings. In addition, the design of the present 2D EEMF incorporates improvements over the one prior commercial underwater 2D EEMF, developed in 1994 by the same company that developed the present one. Notable advanced features of the present EEMF include the following: 1) High sensitivity and spectral resolution are achieved by use of an off-the-shelf grating spectrometer equipped with a sensor in the form of a commercial astronomical- grade 256 532-pixel charge-coupled-device (CCD) array. 2) All of the power supply, timing, control, and readout circuits for the illumination source and the CCD, ancillary environmental monitoring sensors, and circuitry for controlling a shutter or filter motor are custom-designed and mounted compactly on three circuit boards below a fourth circuit board that holds the CCD (see figure). 3) The compactness of the grating spectrometer, CCD, and circuit assembly makes it possible to fit the entire instrument into a compact package that is intended to be maneuverable underwater by one person. 4) In mass production, the cost of the complete instrument would be relatively low - estimated at approximately $30,000 at 2005 prices

A radiographic study of the effect of food, exercise, and tranquilizers on gastrointestinal motility of the canine

Call number: LD2668 .T4 1964 R47Master of Scienc

Critical Thinking Dispositions of Agricultural Communications Students

Critical thinking, a reasoned, purposive, and introspective approach to solving problems, has received increased attention from agricultural educators. This study of agricultural communications students utilized a directly administered survey to investigate critical thinking dispositions of agricultural communications students at 12 universities. Results indicated that agricultural communications student respondents tend to be highly innovative in their thinking, an important trait in the field of communications. Results also indicated that few agricultural communication students would be classified as having a strong disposition toward critical thinking, while a larger number would be classified as weak in critical thinking dispositions

Structural Characterization of Phosphatidyl-myo-Inositol Mannosides from Mycobacterium bovis Bacillus Calmette Gúerin by Multiple-Stage Quadrupole Ion-Trap Mass Spectrometry with Electrospray Ionization. II. Monoacyl- and Diacyl-PIMs

The multiple-stage ion-trap mass spectrometric approaches towards to the structural characterization of the monoacyl-PIM (triacylated PIM) and the diacyl-PIM (tetracylated PIM), namely, the PIM (diacylated PIM) consisting of one or two additional fatty acid substituents attached to the glycoside, respectively, were described. While the assignment and confirmation of the fatty acid substituents on the glycerol backbone can be easily achieved by the methods described in the previous article, the identity of the glycoside moiety and its acylation state can be determined by the observation of a prominent acylglycoside ion arising from cleavage of the diacylglycerol moiety ([M − H − diacylglycerol]−) in the MS2-spectra of monoacyl-PIM and diacyl-PIM. The distinction of the fatty acid substituents on the 2-O-mannoside (i.e., R3CO2H) from that on the inositol (i.e., R4CO2H) is based on the findings that the MS3-spectrum of [M − H − diacylglycerol]− contains a prominent ion arising from further loss of the fatty acid at the 2-O-mannoside (i.e., the [M − H − diacylglycerol − R3CO2H]− ion), while the ion arising from loss of the fatty acid substituent at the inositol (i.e., the [M − H − diacylglycerol − R4CO2H]− ion) is of low abundance. The fatty acyl moiety on the inositol can also be identified by the product-ion spectrum from MS4 of the [M − H − diacylglycerol − R3CO2H]− ion, which gives rise to a prominent ion corresponding to loss of R4CO2H. An [M − H − acylmannose]− ion was also observed in the MS2-spectra and, thus, the identity of the fatty acid substituent attached to 2-O-mannoside can be confirmed. The combined information obtained from the multiple-stage product-ion spectra from MS2, MS3, and MS4 permit the assignment of the complex structures of monoacyl-PIMs and diacyl-PIMs in a mixture isolated from M. bovis Bacillus Calmette Guérin

Effect of Sedentary and Physical Activities on Children’s Food Choice

International Journal of Exercise Science 10(5): 702-712, 2017. Childhood obesity is a growing public health concern. Research has shown sedentary behavior (SB) increases children’s unhealthy food consumption, while physical activity (PA) decreases caloric intake and increases energy expenditure. The purpose of this study was to examine child snack choice following a bout of active, SB, and a mix of SB and active (SB-A). Participants included a volunteer sample of children (n=24) ranging from 9-13 years of age. A within-subjects simple experimental design was used, and children participated in three conditions: active, SB, and SB-A. After each condition, the children were asked to choose one snack from two healthy and two unhealthy options. The children were randomized into one of the six possible condition sequences (4 children per group) based on when they enrolled in the study. Data were analyzed in SPSS (v21) using the Friedman, Wilcoxon Signed-Rank, and Kruskal-Wallis tests. There was not a statistically significant difference in the overall model comparing the three conditions on snack choice (p=0.15). Overweight/obese children were significantly more likely than normal weight children to choose a healthier snack option after the active condition (p=0.02). There was no difference between boys and girls for snack choice following the active (p\u3e0.05), SB (p\u3e0.05), and SB-A (p\u3e0.05). Our overall findings suggest SB and active had no effect on children’s snack choice. Promoting PA to children who are overweight/obese could lead to decreased energy intake and increased energy expenditure combating the obesity epidemic

Core handling and processing for the WAIS Divide ice-core project

On 1 December 2011 the West Antarctic Ice Sheet (WAIS) Divide ice-core project reached its final depth of 3405 m. The WAIS Divide ice core is not only the longest US ice core to date, but is also the highest-quality deep ice core, including ice from the brittle ice zone, that the US has ever recovered. The methods used at WAIS Divide to handle and log the drilled ice, the procedures used to safely retrograde the ice back to the US National Ice Core Laboratory (NICL) and the methods used to process and sample the ice at the NICL are described and discussed