The Effects of Triclosan Derivatives against the Growth of Staphylococcus Aureus

Triclosan is an antimicrobial commonly used in many different antiseptics and everyday products. Unfortunately, many bacteria are now resistant to triclosan due to innate resistance, mutations in the fabI gene, and/or overexpression of certain other genes (soxS, marA, and an efflux pump encoded by acrAB). Therefore, it is essential that drugs be developed to destroy bacteria now resistant to triclosan. In this experiment, four different derivatives of triclosan were tested for antibacterial capabilities under the supervision of Dr. Hubbard at Liberty University. The derivatives were synthesized by Professor McGibbon (professor of organic chemistry at LU). Solutions of 4.0 ug/mL of each derivative were made and then tested against S. aureus for inhibition capabilities. Some of the derivatives seemed to have some inhibition capabilities, but none of them were as inhibitive as triclosan itself. Of special note, some of the results seem to indicate that the added benzene ring may inactivate triclosan’s antibacterial capabilities while the added chlorines provide at least some inhibition to S. aureus. Ultimately, the derivatives of triclosan did not have high inhibition rates at 4.0 ug/mL, but more experiments need to be performed in order to determine their effects at higher concentrations and on different species of bacteria. Hopefully, the data gathered and inferred from this experiment, including several valuable dissolving ratios and laboratory techniques which were discovered, will be implemented into future research on triclosan derivatives that will lead to the discovery of compounds even more inhibitive against bacteria growth than triclosan

Second-order nonlinearities and crystal structure of 2-methoxy-4'-nitro-(E)-stilbene

Second-order nonlinear optical (NLO) properties of crystalline materials depend both on the magnitude of the molecular hyperpolarizability (β) and on the orientation of the chromophores in the crystal lattice. If the molecular hyperpolarizability is to result in a nonzero macroscopic nonlinearity, the molecule must crystallize in a noncentrosymmetric space group. The design of new second-order NLO materials requires one both to address the structure-property relationships that govern β and to develop methodologies that favor noncentrosymmetric crystallization. Methods used to encourage noncentrosymmetric crystallization include the use of chiral molecules, the incorporation of functional groups that encourage asymmetric intermolecular hydrogen bonding, the synthesis of molecules with very small ground-state dipole moments but larger excited-state dipole moments, and the variation of counterion with ionic chromophore

Second-order nonlinearities and crystal structure of 2-methoxy-4'-nitro-(E)-stilbene

Second-order nonlinear optical (NLO) properties of crystalline materials depend both on the magnitude of the molecular hyperpolarizability (β) and on the orientation of the chromophores in the crystal lattice. If the molecular hyperpolarizability is to result in a nonzero macroscopic nonlinearity, the molecule must crystallize in a noncentrosymmetric space group. The design of new second-order NLO materials requires one both to address the structure-property relationships that govern β and to develop methodologies that favor noncentrosymmetric crystallization. Methods used to encourage noncentrosymmetric crystallization include the use of chiral molecules, the incorporation of functional groups that encourage asymmetric intermolecular hydrogen bonding, the synthesis of molecules with very small ground-state dipole moments but larger excited-state dipole moments, and the variation of counterion with ionic chromophore

A Review of Quality of Life Measures in Dry Eye Questionnaires

Dry eye disease (DED) is an ocular disease that affects 5% to 17% of the US population. Because of the negative effects of DED on patients’ quality of life (QOL), disease-specific questionnaires that assess QOL in patients with dry eyes are essential in the monitoring and management of this chronic ocular condition. This review provides clinicians and researchers with a summary of the current questionnaires available for assessing QOL in patients with dry eyes

Confinement and Processing Can Alter the Morphology and Periodicity of Bottlebrush Block Copolymers in Thin Films

Bottlebrush block copolymers (BBCPs) are intriguing architectural variations on linear BCPs with highly tunable structure. Confinement can have a significant impact on polymer assembly, giving rise to changes in morphology, assembly kinetics, and properties like the glass transition. Given that confinement leads to significant changes in the persistence length of bottlebrush homopolymers, it is reasonable to expect that BBCPs will see significant changes in their structure and periodicity relative to the bulk morphology. Understanding how confinement influences assembly will be important for designing BBCPs for thin film applications including membranes, integrated photonic structures, and potentially BCP lithography. In order to study the effects of confinement on BBCP conformation and morphology, a blade coating was used to prepare films with continuous variation in film thickness. Unlike thin films of linear BCPs, islands/holes were not observed, and instead mixtures of parallel and perpendicular morphologies emerge after annealing. The lamellar periodicity (L₀) of the morphologies is found to be thickness dependent, increasing L₀ with decreasing film thickness for blade coated films. Films coated out of tetrahydrofuran (THF) resulted in a single well-defined lamellar periodicity, verified through atomic force microscopy (AFM) and grazing incidence small-angle X-ray scattering (GISAXS), which increases dramatically from the bulk value (30.6 nm) and continues to increase as the film thickness decreases. The largest observed L₀ was 65.5 nm, and this closely approaches the estimated upper limit of 67 nm corresponding to a fully extended backbone in a bilayer arrangement. Films coated out of propylene glycol methyl ether acetate (PGMEA) resulted in a mixture of perpendicular lamellae and a smaller, likely cylindrical morphology. The lamellar portion of the film shows the same thickness dependence as the lamellae observed in the THF coated films. The scaling of the lamellar L₀ with respect to film thickness follows predictions for confined semiflexible polymers with weak excluded volume interactions and can be related to models for confinement of DNA. Spin coated films shows the same reduction in periodicity, although at very different film thicknesses. This result suggests that the material has shallow free-energy barriers to transitioning between different L₀ and morphologies, a property that could be taken advantage of for patterning diverse structures with a single material

Bayesian Life Test Planning for the Log-Location-Scale Family of Distributions

This paper describes Bayesian methods for life test planning with censored data from a log-location-scale distribution, when prior information of the distribution parameters is available. We use a Bayesian criterion based on the estimation precision of a distribution quantile. A large sample normal approximation gives a simplified, easy-tointerpret, yet valid approach to this planning problem, where in general no closed form solutions are available. To illustrate this approach, we present numerical investigations using the Weibull distribution with Type II censoring. We also assess the effects of prior distribution choice. A simulation approach of the same Bayesian problem is also presented as a tool for visualization and validation. The validation results generally are consistent with those from the large sample approximation approach

Estrogen and progesterone induce persistent increases in p53-dependent apoptosis and suppress mammary tumors in BALB/c-Trp53+/- mice

Introduction Treatment with estrogen and progesterone (E+P) mimics the protective effect of parity on mammary tumors in rodents and depends upon the activity of p53. The following experiments tested whether exogenous E+P primes p53 to be more responsive to DNA damage and whether these pathways confer resistance to mammary tumors in a mouse model of Li-Fraumeni syndrome. Methods Mice that differ in p53 status (Trp53+/+, Trp53+/-, Trp53-/-) were treated with E+P for 14 days and then were tested for p53-dependent responses to ionizing radiation. Responses were also examined in parous and age-matched virgins. The effects of hormonal exposures on tumor incidence were examined in BALB/c-Trp53+/- mammary tissues. Results Nuclear accumulation of p53 and apoptotic responses were increased similarly in the mammary epithelium from E+P-treated and parous mice compared with placebo and age-matched virgins. This effect was sustained for at least 7 weeks after E+P treatment and did not depend on the continued presence of ovarian hormones. Hormone stimulation also enhanced apoptotic responses to ionizing radiation in BALB/c-Trp53+/- mice but these responses were intermediate compared with Trp53+/+ and Trp-/- tissues, indicating haploinsufficiency. The appearance of spontaneous mammary tumors was delayed by parity in BALB/c-Trp53+/- mice. The majority of tumors lacked estrogen receptor (ER), but ER+ tumors were observed in both nulliparous and parous mice. However, apoptotic responses to ionizing radiation and tumor incidence did not differ among outgrowths of epithelial transplants from E+P-treated donors and nulliparous donors

The Genome Sequence of the Leaf-Cutter Ant Atta cephalotes Reveals Insights into Its Obligate Symbiotic Lifestyle

Leaf-cutter ants are one of the most important herbivorous insects in the Neotropics, harvesting vast quantities of fresh leaf material. The ants use leaves to cultivate a fungus that serves as the colony's primary food source. This obligate ant-fungus mutualism is one of the few occurrences of farming by non-humans and likely facilitated the formation of their massive colonies. Mature leaf-cutter ant colonies contain millions of workers ranging in size from small garden tenders to large soldiers, resulting in one of the most complex polymorphic caste systems within ants. To begin uncovering the genomic underpinnings of this system, we sequenced the genome of Atta cephalotes using 454 pyrosequencing. One prediction from this ant's lifestyle is that it has undergone genetic modifications that reflect its obligate dependence on the fungus for nutrients. Analysis of this genome sequence is consistent with this hypothesis, as we find evidence for reductions in genes related to nutrient acquisition. These include extensive reductions in serine proteases (which are likely unnecessary because proteolysis is not a primary mechanism used to process nutrients obtained from the fungus), a loss of genes involved in arginine biosynthesis (suggesting that this amino acid is obtained from the fungus), and the absence of a hexamerin (which sequesters amino acids during larval development in other insects). Following recent reports of genome sequences from other insects that engage in symbioses with beneficial microbes, the A. cephalotes genome provides new insights into the symbiotic lifestyle of this ant and advances our understanding of host–microbe symbioses

Third-order susceptibilities of soluble polymers derived from the ring opening metathesis copolymerization of cyclooctatetraene and 1,5-cyclooctadiene

We wish to report some preliminary results on the nonlinear optical properties of a new class of polymers synthesized by the ring-opening metathesis polymerization of highly unsaturated monomers. Mixtures of cyclooctatetraene, 1, and 1,5-cyclooctadiene, 2, have been polymerized by using the tungsten carbene complex 3 as the catalyst (see Figure 1). The solution polymerization of monomers 1 and 2 in tetrahydrofuran leads to an essentially random coploymer. The monomers contain exclusively cis double bonds and no attempt has been made to isomerize the double bonds in the resulting polymer. The general constitution of the copolymers is also shown in Figure 1 (an all-trans geometrical configuration is shown for simplicity)