On the determination of the optical constants n(λ) and α(λ) of thin supported films

A general method was developed to determine the optical constants n(λ) and α(λ) for a thin semiconducting or metallic supported film from five or three measurements of the transmittance and the reflectance.Exact formulae were deduced for oblique incidence transmittance and reflectance considering multiple coherent reflections in the films and incoherent reflections in the non-absorbing substrate. A computer program was developed that, when used as a subroutine of a European Organization for Nuclear Research program called MINUIT, allowed the method to be tested for gold, silicon, CdS, Cu₂S (chalcocite) and Cu_1.96S (djurleite) polycrystalline films.A residual function shows good agreement between the calculated and measured values of the transmittance and the reflectance when a careful choice of the value of the thickness is made.     

Production and composition of milk from Jersey cows administered bovine somatotropin and fed ruminally protected amino acids

Eight multiparous and 4 primiparous Jersey cows averaging 92 d of lactation were utilized in a replicated 4 x 4 Latin square design with 28-d periods to determine responses to bovine somatotropin (bST) and ruminally protected Met and Lys when diets were fed that contained supplemental fat. Treatments were 1) control [no bST or ruminally protected amino acids (AA)], 2) control plus bST, 3) control plus ruminally protected AA, and 4) control plus bST plus ruminally protected AA. Dry matter intake was increased by bST but was unaffected by ruminally protected AA. Milk yield was increased by bST but was not altered by ruminally protected AA compared with the control diet. The bST tended to increase percentages of fat and total solids in milk and increased yields of fat, protein, 3.5% fat-corrected milk, and total solids. Ruminally protected AA increased percentages of fat, protein, and total solids in milk; however, yields of milk components were unaffected by ruminally protected AA. Body weight and body condition scores were unaffected by treatment. Concentrations of essential AA in plasma were unaffected by bST administration. Ruminally protected Met and Lys increased the concentration of Met and tended to increase the concentration of Lys in plasma. The lack of an increase in yields of milk and milk protein when ruminally protected AA were fed suggests that adequate amounts of Met and Lys were supplied by the control diet and protein reserves of the cows to meet the AA requirements for synthesis of milk and milk components.     

The prospective relationships between smoking and weight in a young, biracial cohort: the Coronary Artery Risk Development in Young Adults Study

This study examined the relationship between smoking status and weight change from baseline to Year 7 in a large biracial cohort, the Coronary Artery Risk Development in Young Adults study. Unadjusted for covariates, only male smokers weighed less than nonsmokers, with no effect among women. Adjusted for covariates, male and female smokers weighed less than nonsmokers at baseline, adjusted for age, total energy intake, alcohol intake, and physical fitness. Over the 7-year follow-up, all smoking status groups gained weight, including continuous smokers and initiators. Weight gain was greatest among those who quit smoking. Weight gain attributable to smoking cessation was 4.2 kg for Whites and 6.6 kg for Blacks. Smoking had a small weight-attenuating effect on Blacks. No such effects, however, were observed among Whites. These results suggest, at least in younger smokers, that smoking has minimal impact on body weight.     

The significance and trend of hypertension related deaths in urban Sierra Leonean Africans

This study tried to show the contributory role of ions (cations and anions) to great contrast in the goitre prevalence between Bassa and Jos Local Government Areas, both of Plateau State, Nigeria. In pursuance of this, the concentration of cations (Ca++, Fe++, K+, Mg++, Na+, & Zn++) and anions (C1-, F, I-, & NO-3) in soil and drinking water in the two LGAs were determined and their results compared and correlated with the goitre prevalence of these areas. It was observed that both Bassa and Jos LGAs have very low but similar amounts of iodide ions in their soils. Besides, Bassa LGA contained more ions in both soil and drinking water than Jos LGA. In conclusion, the results appear to suggest that the higher ion contents of both soil and drinking water in Bassa LGA exacerbated the coexisting low iodide condition of the LGA, thus resulting in the higher goitre prevalence found in the LGA.     

Optimal Linear Control of Modular Multi-Level Converters with a Prescribed Degree of Stability

Abstract

In this paper, a new control approach using an optimal linear control with prescribed degree of stability for modular multi-level converters (MMC) is presented and analyzed. The proposed controller relies on a linear quadratic regulator with integral action which brings the ability of state variable reference tracking for modular multi-level converters. Since MMC is a complex system with several state variables, a unified control system design for this system is vital. The proposed controller of this study is designed to obtain wider stability margin thanks to the implementation of prescribed degree of stability concept to minimize the quadratic performance index of the control structure. By means of this method, the poles of the closed-loop system will be shifted to the desired places in the left half side of the S-plane. The main advantages of this control strategy compared to previous methods are that it will be possible to control the state of energy for each phase separately, while there will be superior tolerance to nonlinearities and the enhanced stability margin with less sensitivity to plant-parameter variations. The performance of the designed controller is verified through MATLAB^TM simulations (The MathWorks, Natick, MA, USA) with the nonlinear model of MMC.     

Mechanical behavior of cold-water fish gelatin gels crosslinked with 1,4-butanediol diglycidyl ether

In this work, chemical crosslinking with 1,4-butanediol diglycidyl ether (BDDGE) is used as strategy to enhance mechanical performance of fish gelatin (FG) gels in order to meet the properties' range of mammalian gelatin physical gels. Joint analysis of free amino groups, swelling ratio, and total soluble material indicates that crosslinking degree increases with increasing FG concentration and it is favored by a 0.2 BDDGE/FG ratio. Increasing crosslinking degree enhances gel indentation strength and shear modulus (μ) while decreases fracture toughness (G_IC). Measured μ and G_IC values lies within the range exhibited by mammalian gelatin physical gels, but the relationship between these parameters is opposite. This is due to the different fracture mechanisms occurring in chemically crosslinked and physical gels.     

Measurements of normal boiling points of fatty acid ethyl esters and triacylglycerols by thermogravimetric analysis

At present, a large number of studies of biodiesel production process using simulation packages are being developed. In these studies, vegetable oils and biodiesels are characterized in the software through representative compounds because of they are not in the compounds database of commercial simulators. With the aim to achieve a successfully characterization in these kinds of software, some properties of the substances must be available. The normal boiling point (NBP) is the most important property due to the fact that this property along with group contribution methods allows other properties calculation such as, e.g., critical properties and temperature dependency properties. In this work, a thermogravimetric analysis (TGA) method for rapid measurement of normal boiling points of two triacylglycerols and four ethyl esters, i.e., triolein, tripalmitin, ethyl oleate, ethyl palmitate, ethyl linoleate and ethyl ricinoleate, was used. Nowadays, in the open literature exists few data available about ethyl esters properties; hence, the results obtained here will contribute in the proposal, analysis, and evaluation of ethyl esters (biodiesel) virtual plants using reliable simulation packages. In addition, a more accurate characterization of compounds and therefore more accurate simulation results can be obtained when they are used.