Rydberg-London Potential for Diatomic Molecules and Unbonded Atom Pairs

We propose and test a pair potential that is accurate at all relevant distances and simple enough for use in large-scale computer simulations. A combination of the Rydberg potential from spectroscopy and the London inverse-sixth-power energy, the proposed form fits spectroscopically determined potentials better than the Morse, Varnshi, and Hulburt-Hirschfelder potentials and much better than the Lennard-Jones and harmonic potentials. At long distances, it goes smoothly to the correct London force appropriate for gases and preserves van der Waals's "continuity of the gas and liquid states," which is routinely violated by coefficients assigned to the Lennard-Jones 6-12 form.Comment: Five pages, 10 figure

Parametrization of the Hybrid Potential for Pairs of Neutral Atoms

The hybrid form is a combination of the Rydberg potential and the London inverse-sixth-power energy. It is accurate at all relevant distance scales and simple enough for use in all-atom simulations of biomolecules. One may compute the parameters of the hybrid potential for the ground state of a pair of neutral atoms from their internuclear separation, the depth and curvature of their potential at its minimum, and from their van der Waals coefficient of dispersion.Comment: 7 pages, 11 figures, includes lithium, sodium, & potassium dimers, minor correction

Vibrations of a chain of Xe atoms in a groove of carbon nanotube bundle

We present a lattice dynamics study of the vibrations of a linear chain of Xe adsorbates in groove positions of a bundle of carbon nanotubes. The characteristic phonon frequencies are calculated and the adsorbate polarization vectors discussed. Comparison of the present results with the ones previously published shows that the adsorbate vibrations cannot be treated as completely decoupled from the vibrations of carbon nanotubes and that a significant hybridization between the adsorbate and the tube modes occurs for phonons of large wavelengths.Comment: 3 PS figure

The positive control of ilvC expression in E. coli K-12

The mechanism of ilvC expression in Escherichia coli was investigated. To carry out this work several different approaches were used. Firstly, sequencing of the ilvY2143 allele which carries a mutation that makes ilvC expression constitutive was completed. The location of the mutation was determined to be at the 5 end of the gene. It is a single base substitution (G to A) at position 87 (counted from the transcription startpoint of ilvY). This results in a change of the codon for one amino acid. Glutamine in wild-type ilvY protein is replaced by lysine in the constitutive one. This substitution in the polypeptide of the upsilon protein (product of the ilvY gene) was found to be solely responsible for making the up silon protein independent of the ilvC gene substrates (a-acetohydroxybutyrate or acetolactate) needed for ilvC induction. Two approaches were used to determine the direction of ilvY trancription. One of these employed a gene fusion technique which involves two DNA fragments of ilvY being fused separately to a promoterless lacZ gene, then monitoring the expression of lacZ. The other approach involved the labeling of the upsilon protein withes -methionine after expression of ilvY in a T7 RNA polymerase dependent promoter system. DNA-binding activity of upsilon protein was investigated. This was carried out in two assays, filter binding and gel retardation assays. These assays were employed to monitor purification of upsilon protein to near homogeneity. Upsilon protein has a subunit size of 35 kd and a native molecular weight of approximately 211 kd, suggesting upsilon exists as a hexamer. Finally, in vitro activities of the upsilon protein were tested using transcriptional and coupled transcription-translation assays. Upsilon protein was shown to cause elevation of ilvC transcription. Two models for the action of the upsilon protein in regulating the transcription of the ilvYC are proposed

Absent Schlemm's Canal With Reduction in Intraocular Pressure Through Uveoscleral Pathway Observed After Conditional Deletion of AP-2β in the Mouse

A unique mouse model recently developed in our laboratory (AP-2β TMR-KO) achieves a conditional deletion of transcription factor AP-2β from the developing periocular mesenchyme and its derivatives using MgpCre/loxP technology. These mutants fail to develop SC and exhibit increased IOP, which temporarily reduces with latanaprost treatment. Here we have shown changes in protein and gene expression of various SC markers. Specifically, Prox1 expression was detected in the wildtype at P4, P10, and P14, but was absent in the AP-2β TMR-KO mice at those stages. Klf4 expression was not present in either wildtype or mutant at P4 but was detected at P10 and P14 in the wildtype only. Additionally, decreased gene expression was observed of Prox1, Klf4, and Tie2 in the SC region at P4 and P10, and of Angpt1 in the trabecular meshwork region, in mutant eyes. Furthermore, dextran tracer studies were performed to assess aqueous outflow in wildtype and AP-2β TMR-KO mice; dextran was detected in regions of both outflow pathways in the wildtype but was clustered in the anterior chamber in the mutant, with the corrected total fluorescence significantly higher in the anterior chamber and significantly lower in regions of outflow for the mutant relative to wildtype. Upon latanaprost treatment, dextran was similarly present in the wildtype, but detected further along the uveoscleral pathway in the mutant with time. The data generated in this project provides more insight into the role of AP-2β in the development and function of the aqueous humor outflow pathways. This information will be critical to elucidating the genetic cascade through which AP-2β regulates anterior segment development. Additionally, this project points to the potential of the AP-2β TMR-KO mice as a model for glaucoma.ThesisMaster of Science (MSc)Glaucoma is one of the leading causes of blindness in the world, with an estimated 76 million people affected by it. This number is projected to increase by almost 30% over the next decade. This drastic increase is a threat to healthcare systems and care facilities, as it will put a great strain on the number of resources that can be provided. In addition, age-related visual disability can lead to several other conditions due to increased risk of injury. Irreversible blindness with glaucoma occurs when the retinal ganglion cells in the eye are damaged due to elevated intraocular pressure, which results from a disruption in aqueous humor drainage. Data from this thesis provides important insight into the development of an important aqueous humor drainage structure, Schlemm’s canal, and points to the potential of a mutant mouse model as a model for glaucoma

Adulteration of Spices: A Review

Food is one of the basic needs for every living being and is very important aspect for life. But now a day’s foods are affected by different adulterants. Adulteration is a substance which reduces the vital importance of food. Adulterants like metanil yellow (an artificial colour) is used to intensify the colour of the turmeric powder also adulterants like chalk powder, brick powder and toxic substances are added to gain profit and to lower the cost so as to compete with the market. Such adulterants can lead to anaemia, paralysis, brain damage, stomach disorders and also cancer. Spices may also be contaminated because of conditions under which they are cultivated and harvested. Contaminated spices have been reported to cause some diseases and spoilage caused by food. This article provides some information about adulteration of spices

The Determination of Bound Water in Waste Phosphatic Clay

Phosphatic clay is a by-product of phosphate strip mining, particularly in Florida, USA. This waste material occupies about 100 000 acres of land which could be utilized for other causes. Thus, its use as an alternating cementing material for the addition into the mixing matrix of cement paste and concrete to yield higher strength would be profitable for both materials involved. But the biggest drawback faced is that the phosphatic clay possesses high water holding capacity. The water is thus not available for mixing purposes when added to cement paste and concrete and is thus known as bound water. It is therefore essential to determine the amount of bound water to phosphatic clay which shall not be available for the hydration reaction of cement in cement paste and concrete

Association of the level of cognition and obesity among middle-aged adults in Sri Lanka

Background: Cognition is the collection of an intellectual process, such as perception, thinking, and reasoning for goal-directed behaviours. The obesity-associated cognitive functions (CFs) was varied due to inconsistency of the findings and it is also context bounded. The objective was to assess the association between cognitive function and obesity among middle-aged adults in Sri Lanka.Methods: A descriptive study was conducted among middle-aged adults aged between 50-60 years in Colombo District, Sri Lanka. While Generalized obesity was estimated by the WHO cutoff of body mass index (BMI) while the central obesity was determined using and waist hip ratio (WHR). CFs was assessed using a validated Montreal cognitive assessment (MoCA) and the Mini-mental state examination (MMSE) tools.Results: The study sample consisted of 83 subjects of each obese and normal weight categories, while 50% were females. Middle-aged adults with obesity showed significantly lower CF scores in both MoCA and MMSE compared to the normal-weight adults (p<0.01). In addition, lower MMSE scores were significantly associated with high WHR values (p<0.05). The level of education of adults was a significant predictor of cognitive functions among middle-aged adults (p<0.05).Conclusions: Therefore, the results further confirmed that obesity-associated cognitive impairment among middle-aged adults and further research is warranted to clarify the cause and effect relationship between obesity and body composition.