1941 research outputs found
Sort by
Solubility of carbamazepine in aqueous solutions of sodium dodecyl sulfate
No full textCarbamazepine (CZ) is a hydrophobic antiepileptic drug with a very low water solubility. It is important to identify means of improving the solubility of such drugs for better formulation and absorption. One approach to increasing solubility of hydrophobic drugs is to solubilize them in surfactant micelles. Surfactants are compounds that form micelles above a certain critical micelle concentration (cmc). Hydrophobic drug are able to dissolve in the non-polar interior of these micelles and therefore achieve higher concentrations in solution.
We have investigated the solubility of CZ in solutions of sodium dodecyl sulfate (SDS), an anionic surfactant frequently used in pharmaceutical systems. Concentrations of SDS below and above its cmc (8 mM) were used. Excess CZ was added to SDS solutions of varying concentrations, and the systems allowed to equilibrate at 26ºC for at least seven days. The mixtures were filtered, diluted appropriately with ethanol and analyzed spectrophotometrically at 286 nm using a Beckman DU7500 UV-visible diode array spectrophotometer.
Our observations show that the aqueous solubility of CZ at 26ºC is 4.23 x 10-4 M. The solubility of CZ increases as a function of SDS concentration above the cmc. For example, CZ solubility is 4.4 times greater in 10mM SDS, 12.7 times greater in 20 mM SDS, and 59.8 times greater in 80mM SDS. Very little solubility enhancement is seen at SDS concentrations below the cmc. The results confirm that SDS micelles can solubilize CZ and significantly increase its total aqueous solubility
Drake University Virtual Reality Project
No full textThe Drake University Virtual Reality Project is an ongoing endeavor with the primary goal of producing a working CAVE system, which is a virtual, immersive 3D theater. The Drake Virtual Reality Project utilizes low cost computer graphics hardware along with student developed software to create a virtual environment. The lab is motivated to be completely student designed and orientated. It is run mostly by undergrad students and overseen by professors. The Drake VR Lab is designed to give computer science students at Drake new research opportunities and provide experience on a larger modular project
Creating an object-oriented wireless network simulator
Get PDFWireless routing protocols are currently among the most actively researched areas in computer science. There are hundreds of such protocols already established and even more under development. Wireless network simulators however have not received as much attention. Currently, there are only a handful of these simulators which are powerful tools for analyzing routing protocols. But, altering their code can be tremendously cumbersome due to the great level of detail they were developed. Some of these systems were designed using the object-oriented programming languages but failed to take into account the various strengths of using such languages, such as inheritance and polymorphism furthermore making them less extensible. As we have researched wireless routing at Drake University, we have found the need to develop our own wireless simulator as a test environment for our protocols. The goal of this simulator was to improve the ability to add new and sometimes very different wireless protocols to the system and remove the overhead and complexity in the layers of wireless communication. We felt to develop such protocols and test features of interest to us we should not be required to have an in-depth knowledge of the networking layers
Selective epoxidation of olefines using dioxirane system
No full textOxidation of alkenes using 1,3-dichloromethyldioxirane produces good to excellent yield of epoxide products. The reaction system is facile, mild, efficient and safe. Our results involving epoxidation of various alkene substrates with different degree of ionizibilities, along with our studies involving selectivity experiments in 1:1 competitive alkenes epoxidation reactions will be presented
Inability to easily predict individual deaths in a hemorrhage and resuscitation model
No full textWhile working on a hemorrhage with low-pressure stabilization protocol, we examined the possibility of identifying individual animals’ short term outcomes prior to occurrence using the hemorrhage patterns of variables currently suggested to identify patients and animals in severe hemorrhagic shock. Methods: 8 anesthetized, ventilated dogs were hemorrhaged (H, 90min mean arterial pressure [MAP]=35-40mmHg or MAP10min or MAP1min), hypotensively stabilized (S, 120min enalaprilat 0.01mg/kg/hr + hemoglobin based oxygen carrier [HBOC] or 7.8% hypertonic saline dextran 70 [HSD] for MAP=40-45mmHg), resuscitated (60min lactated Ringer’s for MAP=75-80mmHg), monitored (60min no fluids), and euthanized. Results: 2 non-survivors: NS1 (1 of 5 HBOC, died 117min into S) and NS2 (1 of 3 HSD, died 9min into S). Patterns of continuous, non-invasive variables: Non-survivors had the highest and 2nd lowest heart rates. All animals’ mean arterial pressures and end-tidal CO2s (related to cardiac output) were intermingled. Foreleg muscle StO2 was highest in NS1 and intermingled with the 4 lowest survivors in NS2. Patterns of discontinuation and/or invasive variables: Shed blood in NS1, NS2, and 2 survivors were equivalent (38-40mL/kg) and less than the 4 other survivors (45-56mL/kg). SvO2 values were intermingled. Start H base excess values were intermingled. End H base excesses were NS1 = -18.8, NS2 = -19.2, 2 survivors each = -19.0, other survivors –13.9 to –17.5 mmol/L. Conclusions: Hemorrhage values and obvious patterns of the monitored variables failed to distinguish individual animals that would undergo cardiovascular collapse despite receiving the same treatment from those that would survive.IA Space Grant, Eagle
Star formation in UV-bright interacting galaxies
No full textGalaxy interactions are known to drive interstellar gas toward the nuclear regions, thus triggering bursts of star formation. To investigate the relationship between galaxy interactions and the induced star formation, we obtained from the 40-inch telescope at Mt. Laguna U, B, V, and R images of NGC3395 & NGC3396 (an interacting pair) and NGC3991, NGC3994, & NGC3995 (an interacting trio), all of which exhibit strong UV emission known to be a signature of vigorous star formation. By comparing our multi-color data with star formation models, we can determine the age and strength of each star-forming region, and thus characterize the star-formation history of each object. One possibility is that interactions produce a “chain reaction” – one burst triggering another burst and so on – which should be discernible from the distribution of ages across the galaxy. We compare results from the NCG3991/4/5 trio with results from the NGC3395/6 pair
Control of poison ivy in managed grassland systems
No full textIn many cases, the first step in an autogenic restoration is to eradicate invasive or undesired species. One management strategy used to reduce cover of invasive species in the Tallgrass prairies or oak savannas of Iowa is to reintroduce a fire regime to an area. An alternative management tool is the use of herbicide, although non-target impacts of the application may cause undesired effects on native biodiversity. The goal of this pilot study was to explore the effects of fire or herbicide treatment on mortality and stem growth of poison ivy, a native but potentially invasive species in Iowa grasslands. We tested the hypothesis late season fire would cause greater above-ground mortality of poison ivy compared to late season herbicide application. A total of twelve, two meter square plots were established with a one meter square in the center receiving a treatment. Six plots were treated with fire and six plots were treated with the herbicide triclopyr in September of 2005. Stem density of poison ivy was measured in all plots before and after management treatment and stem mortality was assessed in April 2006. Preliminary data indicate that herbicide did not result in mortality, but fire did result in top kill. Thus, our results indicate that fire may be effective in eradicating poison ivy in Iowa’s seasonal climate
Learning and memory impairments in mice lacking the M2 subtype of muscarinic receptor
No full textThe neurotransmitter acetylcholine is an important modulator of cognitive functions such as learning, memory, and attention. These functions of acetylcholine are mediated by its binding to five distinct subtypes of muscarinic acetylcholine receptor (M1, M2, M3, M4, M5). It is largely unknown which receptor subtypes mediate which functions of acetylcholine because of the lack of availability of subtype-selective drugs. The present study examined the behavioral functions of the M2 subtype of muscarinic receptor by utilizing mice possessing a null-mutation in the gene for M2 (M2KO mice). Assessments of general health and neurological function found no differences between M2KO and wild-type (WT) mice. In assessments of sensory function, M2KO mice showed increased pain sensitivity relative to WT mice in the tail-flick test and decreased dishabituation to a novel odor in an olfactory habituation-dishabituation test. In tests of learning and memory, M2KO mice were impaired in the acquisition (trials to criterion), but not the retention (72 hr) of a passive avoidance task. M2KO mice were impaired in between-sessions, but not within session habituation, and M2KO mice committed more working memory and reference memory errors in a holeboard test of spatial memory function. M2KO mice showed no impairments in either cued or contextual fear conditioning. In summary, the present behavioral data indicate that the M2 receptor is necessary for normal nociception, olfaction, and cognitive function
The Effects of impoundment depth and isolation on fish species diversity and fish size
No full textA problem for many fisheries managers is trying to maintain a diverse prey base while maximizing predator size. To test the effects of water depth and impoundment isolation on fish size and species composition, two rock-quarry ponds were sampled at the Great Ape Trust in central Iowa during the fall of 2005. One impoundment was shallow and small compared to an adjacent impoundment that was relatively deep and large. The impoundments were isolated from one another for the majority of the year by an extremely shallow, narrow band of water that was subject to lateral transfer from the Des Moines River. We hypothesized that fish of each species will be greater in the larger, deeper pond. Specimens were collected using a throw net, lengths were recorded with a tailors tape, and capture locations were marked using GPS. Two-tailed t-tests were then used to analyze data sets that were standardized using log transformations to assume for normality. Although species composition was found to be identical in both impoundments, significant differences in mean length were only found in two of the five species, bluegill and the common carp. We conclude that factors other than pond depth play a greater role in influencing body size such as dissolved oxygen content and inter- and intra-specific competition
Complementary approaches to identify genes important for chromosome segregation
Get PDFFaithful transmission of chromosomes during cell division is essential to the functioning of the eukaryotic cell. In humans, errors during chromosome segregation are correlated with diseases such as Down Syndrome and cancer. To elucidate the genes and processes required for accurate chromosome segregation, two types of genetic approaches using the model eukaryotic organism Saccharomyces cervisiae (baker’s yeast) are being implemented. Both approaches rely on an assay system in which the segregation of a non-essential yeast artificial chromosome (YAC) is monitored. The first approach begins with the isolation of mutants with defective chromosome segregation and seeks to identify the gene(s) responsible for producing the mutant phenotype. Four previously isolated YAC stability in mitosis mutants (ysm’s 22, 77, 83 and 84) were characterized as having a marked increase in YAC loss. To identify genes that suppress the YAC loss phenotype in these mutant strains, the ysm mutants were transformed with a yeast genomic plasmid library and screened for plasmids that suppress the mutant phenotype. The suppressor candidates were re-screened, and the specific genes responsible for the suppression are currently being determined. The second approach begins with a known mutation on chromosome segregation. Five genes of known function that are suspected to be important for accurate transmission of chromosome (MRC1, MRE11, MUS81, RAD9, and RAD27) are targeted in this analysis. Following deletion of these genes in a yeast strain containing a YAC, the loss rate of the YAC will be experimentally determined in the deletion mutants and compared to the loss rate in a wild-type strain. These investigations are expected to reveal genes important for the process of chromosome segregation