Values Of Di Research Articles

The Role of Lactic Acid Adsorption by Ion Exchange Chromatography

BackgroundThe polyacrylic resin Amberlite IRA-67 is a promising adsorbent for lactic acid extraction from aqueous solution, but little systematic research has been devoted to the separation efficiency of lactic acid under different operating conditions.Methodology/Principal FindingsIn this paper, we investigated the effects of temperature, resin dose and lactic acid loading concentration on the adsorption of lactic acid by Amberlite IRA-67 in batch kinetic experiments. The obtained kinetic data followed the pseudo-second order model well and both the equilibrium and ultimate adsorption slightly decreased with the increase of the temperature at 293–323K and 42.5 g/liter lactic acid loading concentration. The adsorption was a chemically heterogeneous process with a mean free energy value of 12.18 kJ/mol. According to the Boyd_plot, the lactic acid uptake process was primarily found to be an intraparticle diffusion at a lower concentration (<50 g/liter) but a film diffusion at a higher concentration (>70 g/liter). The values of effective diffusion coefficient Di increased with temperature. By using our Equation (21), the negative values of ΔG° and ΔH° revealed that the adsorption process was spontaneous and exothermic. Moreover, the negative value of ΔS° reflected the decrease of solid-liquid interface randomness at the solid-liquid interface when adsorbing lactic acid on IRA-67.Conclusions/SignificanceWith the weakly basic resin IRA-67, in situ product removal of lactic acid can be accomplished especially from an open and thermophilic fermentation system without sterilization.

OPINION DYNAMICS AND COMMUNICATION NETWORKS

This paper examines the interplay of opinion exchange dynamics and communication network formation. An opinion formation procedure is introduced which is based on an abstract representation of opinions as k-dimensional bit-strings. Individuals interact if the difference in the opinion strings is below a defined similarity threshold dI. Depending on dI, different behavior of the population is observed: low values result in a state of highly fragmented opinions and higher values yield consensus. The first contribution of this research is to identify the values of parameters dI and k, such that the transition between fragmented opinions and homogeneity takes place. Then, we look at this transition from two perspectives: first by studying the group size distribution and second by analyzing the communication network that is formed by the interactions that take place during the simulation. The emerging networks are classified by statistical means and we find that nontrivial social structures emerge from simple rules for individual communication. Generating networks allows to compare model outcomes with real-world communication patterns.

Role of glucagon-like peptide-1 analogues on insulin receptor regulation in diabetic rat hearts

This study focused on the regulation and affinity modulation of the insulin receptor of coronary endothelium and cardiomyocytes in nondiabetic and STZ-induced type 1 diabetic rats. Male rats were divided into the following 9 groups: nondiabetic (N), nondiabetic treated with exendin-4 (NE), nondiabetic treated with dipeptidyl peptidase IV (DPP-IV) inhibitor (NDp), diabetic (D), diabetic treated with insulin (DI), diabetic treated with exendin-4 (DE), diabetic co-treated with insulin and exendin-4 (DIE), diabetic treated with DPP-IV inhibitor (DDp), and diabetic co-treated with insulin and DPP-IV inhibitor (DIDp). After the rats were treated for 1 month, a first-order Bessel function was employed to estimate the insulin binding affinity (with time constant tau = 1/k-n) to its receptors on the coronary endothelium and cardiomyocytes using CHAPS-untreated and CHAPS-treated heart perfusion, respectively. The results showed that diabetes (D) decreased the tau value on the coronary endothelium and increased it on cardiomyocytes compared with the nondiabetic group (N). Treatment with insulin and (or) exendin-4, a glucagon-like peptide-1 (GLP-1) analogue, increased tau on the coronary endothelium only. On the coronary endothelium, tau values of DI and DIDp were normalized. Western blots of the insulin receptor showed upregulation in D, downregulation in DI, and normalization in DE and DDp. Immunohistochemistry and RT-PCR findings indicated atrial natriuretic factor (ANF) in all diabetic ventricles, thus ascertaining hypertrophy. Therefore, negative myocardial effects related to the insulin receptor were diminished in diabetic rats treated with DPP-IV inhibitor and, more efficiently, by exendin-4.

Diffusion of &lt;sup&gt;65&lt;/sup&gt;Zn in AZ91 and QE22 Alloys with Saffil Reinforcement-Influence of Interfaces Matrix/Saffil

Diffusion of 65Zn in two commercial Mg-based alloys AZ91 and QE22 with short Saffil fibers was studied. Experiments were carried out in the temperature interval 648 – 728 K by serial sectioning method. The effective diffusion coefficients Deff were compared with 65Zn diffusion coefficients Dv obtained with the same alloys without Saffil fibers. The evaluation of the influence of the interface between the matrix and the fibers upon Deff was done and the zinc diffusion coefficient Di in the interface boundary matrix/Saffil was estimated. Unlike the Arrhenius-like behavior of volume diffusion in both alloys, it was observed that the temperature dependence of both Deff and Di was significantly concave in the measured temperature interval. This behavior was attributed to relaxation of thermo-elastic stresses in the composite induced by a large difference between coefficients of thermal expansion (CTE) of Saffil fibers and metal matrix. The maximum values of Deff and Di, respectively, lie close to 693 K, where CTE has a minimum.

Evaluation of Concentration Dependent Diffusivities of Manganese in the Diffusion Joint Fe/FeMn-Steel by Means of Mathematical-Analytical Methods

When developing new types of materials with special properties for the automotive industry, steels with high content of manganese (up to 25 wt. % Mn) were studied. These steels embody increased failure resistance, high level of deformation hardening, plastic response and high value of energy absorption in crash situations [1,2]. The aim of our work was to study an interaction of a FeMn alloy with pure iron from the view of diffusion processes. For that purpose, diffusion joints Fe/FeMn-steel were created and long-term heated at the temperatures of 800, 900 and 1050 °C. Dependences of diffusivities of Mn on its concentration were calculated from concentration profiles of manganese after diffusion heating applying three analytical methods. In the first method, constant values of diffusivities Di, i = 1,2 for both Fe and steel were taken into account. In the second case a modified Matano-Boltzmann method utilizing polynomials was applied, which simplifies solution in numerous cases. The third method performs the solution of the non-linear equation of diffusion on the assumption of a linear dependence of diffusivity on concentration applying a procedure based on perturbation calculus. The results of the solution will be graphically documented in details together with the description of experiments.

Kinetic study and sorption mechanism of methylene blue and methyl violet onto mansonia (Mansonia altissima) wood sawdust

Batch sorption kinetic experiments were performed to study the adsorption of methylene blue and methyl violet dyes from aqueous solution using mansonia wood sawdust as adsorbent. Operating variables studied include solution pH and particle size of sawdust. Maximum dye removal was observed at a basic pH 10 for both dyes. Sorption kinetic data was fitted to both pseudo-first and pseudo-second-order kinetic models. The experimental data were found to deviate from the straight line of the pseudo-first-order plots after 30 min for the methylene blue and after 15 min for the methyl violet sorption. The pseudo-second-order kinetics was found to fit the experimental data and was able to consistently predict the amount of dye adsorbed over the sorption period and for the range of sawdust particle size used. The process mechanism was found to be complex, consisting of both mass transfer and intraparticle diffusion. Analysis of the sorption data using the Boyd's plot confirms mass transfer as the dominant mechanism for both methylene blue and methyl violet sorption. Mass transfer mechanism was more predominant in the methyl violet sorption and became more dominant as the particle size of the sawdust material increased. This was confirmed by the values of effective diffusion parameter Di, which were found to be higher for methylene blue, and reduced with increasing sawdust particle size. The molecular sizes of the basic dyes and the stability of the positive charge on the dyes played a significant role in their sorption onto the sawdust material.

Vibrational behavior of the phosphates ions in dittmarite-type compounds M′M″PO 4·H 2O (M′ = K +, NH 4+; M″ = Mn 2+, Co 2+, Ni 2+)

The IR and Raman spectra of the isostructural M′M″PO 4·H 2O compounds (M′ = K +, NH 4 +; M″ = Mn 2+, Co 2+, Ni 2+) are reported and discussed with respect to the normal vibrations of the PO 4 3− ions. The vibrational behavior of PO 4 3− is in agreement with its low site symmetry C s in the lattices—the symmetric ν 1 and ν 2 modes are activated in the IR spectra and the degeneration of the asymmetric ν 3 and ν 4 modes is lifted. A relatively large unit-cell group splitting is observed for ν 1 in both the IR and Raman spectra and for ν 3 in Raman spectra. It has been established that the mean wavenumbers of the P O stretches ( ν ¯ PO ) are not affected by the M 2+ ions present, but they are lower for the NH 4-series than for the K-one (predominant influence of both the smaller repulsion potential and the hydrogen bonds in the NH 4-lattices over the influence of the M +–O interactions). The extent of the energetic distortion of the PO 4 3− ions has been estimated based on the spectroscopic data for the site group splitting of the asymmetric modes (Δ ν 3 and Δ ν 4), the separation between the highest and the lowest wavenumbered P O stretches (Δ ν max) and the intensity of ν 1 in the IR spectra. The data provide an evidence that the PO 4 3− ions in KM″PO 4·H 2O are more distorted regarding the P O bond lengths than those in NH 4M″PO 4·H 2O, but their angular distortion is the same in both series. The trends for the energetic distortion of the phosphate ions found from the spectroscopic data correspond to the data for their geometric distortion deduced from the values of the distortion indices DI(PO) and DI(OPO).

HARDNESS AND APPROXIMATION OF GATHERING IN STATIC RADIO NETWORKS

In this paper, we address the problem of gathering information in a specific node (or sink) of a radio network, where interference constraints are present. We take into account the fact that, when a node transmits, it produces interference in an area bigger than the area in which its message can actually be received. The network is modeled by a graph; a node is able to transmit one unit of information to the set of vertices at distance at most dT in the graph, but when doing so it generates interference that does not allow nodes at distance up to dI (dI ≥ dT) to listen to other transmissions. Time is synchronous and divided into time-steps in each of which a round (set of non-interfering radio transmissions) is performed. We give general lower bounds on the number of rounds required to gather into a sink of a general graph, and present an algorithm working on any graph, with an approximation factor of 4. We also show that the problem of finding an optimal strategy for gathering is NP-HARD, for any values of dI and dT. If dI &gt; dT, we show that the problem remains hard when restricted to the uniform case where each vertex in the network has exactly one piece of information to communicate to the sink.

Removal of Coloured Impurities from Caprolactam Solution by Adsorption onto Activated Carbon: Equilibrium and Thermodynamic Studies

A large number of impurities appear during the production of caprolactam. Such impurities — especially coloured impurities — having a maximum UV absorbance at a wavelength of 290 nm, make it quite difficult to isolate the high-purity product. In order to improve the purification technology, the removal of the coloured impurities from caprolactam solution by adsorption onto activated carbon was studied with good results. The thermodynamic and mass-transfer behaviours of the adsorption process were also examined in this study with the values of Di, kid, Ea and E# being calculated. The magnitudes of the thermodynamic parameters ΔG0, ΔH0 and ΔS0 were also evaluated. A negative ΔG0 value confirmed the feasibility of the method and the spontaneous nature of the adsorption process. The positive value of ΔH0 indicated the endothermic nature of the process while the positive value of ΔS0 indicated an increase in the degrees of freedom of the adsorbed species. The value of ΔHiso increased with the extent of adsorption and showed a linear relationship when plotted against ln q.

Origin of the fast magnetization tunneling in tetranuclear nickel single-molecule magnets

Abstract Several tetranuclear nickel(II) single-molecule magnets (SMMs) have been prepared with the general composition of [Ni(hmp)(ROH)X]4 · S, where hmp− is the monoanion of 2-hydroxymethylpyridine, X− is either Cl− or Br− and S is the solvate molecule. Magnetization versus magnetic field hysteresis loops for these Ni4 SMMs show that there is a relatively fast rate of magnetization tunneling (small coercive field) and, in certain cases, an exchange bias present. Detailed measurements have been carried out in order to determine the origin of the fast magnetization tunneling. High-field electron paramagnetic resonance (HFEPR) data were collected on a single crystal of [Zn(hmp)(dmb)Cl]4 doped with a small amount of Ni(II), where, dmb is 3,3-dimethyl-1-butanol. These variable-frequency/temperature data give values of the single-ion zero-field splitting parameters Di and Ei, and the orientations of these interactions, for the single NiII ions in a Zn3Ni complex doped into a Zn4 crystal. HFEPR data were also obtained at many frequencies and temperatures for a single crystal of isostructural [Ni(hmp)(dmb)Cl]4. Rotation of the single crystal such that the external field is positioned in the hard plane clearly establishes that the transverse zero-field interaction B 4 4 is the cause of the fast magnetization tunneling in the S = 4 ground state of this SMM. The magnitude of B 4 4 and the Ni4 D value can be related to the directionality and magnitude of the Di and Ei interactions at the individual NiII ions, determined for the doped crystal. The microenvironments and ligand dynamics were probed by means of a single-crystal X-ray structure at 12 K and by heat capacity data.

Modelos para estimativa do subfator cobertura-manejo (CiII) relativo à erosão entressulcos

A análise de um modelo de erosão é um crítico passo no desenvolvimento de uma ferramenta de predição da erosão aplicável e válida; isso é crucial para avaliar o desempenho dos modelos existentes para assegurar que as estimativas de um modelo condizem com a realidade. O objetivo do presente trabalho foi avaliar modelos para a predição do subfator cobertura e manejo (CiII) relativo à erosão entressulcos. Um experimento fatorial completo foi conduzido com cinco doses de resíduo de milho (0; 0,05; 0,15; 0,40 e 0,80 kg m-2), quatro declives e duas repetições, sob condições de prévio umedecimento para determinar as taxas de erosão entressulcos (Di) e enxurrada (R). Num primeiro experimento, foi avaliada a erodibilidade entressulcos (Ki) e o subfator cobertura e manejo (CiII), em parcelas experimentais de 0,5 x 0,75 m, em solo recentemente preparado. Num segundo experimento, foram avaliados Di, R, Ki e CiII, também em parcelas de 0,5 x 0,75 m, em solo recém- preparado. Os valores de Di, R, Ki e CiII, obtidos no segundo experimento, foram utilizados na avaliação dos modelos testados. Os modelos CiII = e-2,50 CS/100 e CiII = e -2,238 CS/100 apresentaram boas estimativas para o subfator CiII.

Effect of diet forage to concentrate ratio on rumen degradability and post-ruminal availability of protein from fresh and dried lucerne

AbstractThe ruminal degradation of dry matter (DM) and crude protein (CP) and the intestinal availability of CP of four lucerne samples were measured on two diets with lucerne hay to concentrate ratios of 2: 1 (diet F) and 1: 2 (diet C). Two samples of fresh lucerne (third cut) harvested after 2 (FL1) or 8 (FL2) weeks from the previous cut were used together with a sample of lucerne hay (LH) and another of dehydrated lucerne (DL). Rumen degradability, measured by the nylon bag technique, and rumen outflow rates were determined on three rumen cannulated wethers. Intestinal digestibility was determined by the mobile bag technique on three duodenal fistulated wethers. For CP, significantly lower values were observed with diet C than with diet F for the potentially degradable insoluble fraction (0·334 v. 0·397) and its degradation rate (0·093 v. 0·134 per h). As a consequence, the effective degradability was also lower with diet C (0·746 v. 0·821; P = 0·059). Effective degradability of DM was also apparently lower with diet C (0·596 v. 0·634). With both diets, the intestinal digestibility decreased in all the samples with increase of ruminal incubation time according to a simple exponential equation. The undegraded CP digested in the gut (Di) and therefore the effective intestinal digestibility (EID) were derived from this exponential function according to the rumen outflow of undegraded CP. Mean values of Di (expressed as proportion of food CP content) were respectively 0·091 and 0·142 for F and C diets and 0·084, 0·115, 0·116, and 0·152 for FL1, FL2, LH and DL samples. Lower rumen degradability was partially compensated for by higher Di values resulting in a close correlation between both parameters (r = –0·965; P 0·001). The change of the digestion site associated with the reduction of the effective degradability of CP produced also an increase in the undigested CP as a proportion of food CP. So, these values are respectively 0·087 and 0·112 for F and C diets and 0·053, 0·109, 0·096, and 0·141 for FL1, FL2, LH, and DL samples. No difference in EID between F and C diets was observed (0·529 v. 0·563). For samples, the only effect (P 0·05) was recorded between FL1 (0·618) and the other samples (0·509, 0·544 and 0·512 for FL2, LH, and DL, respectively).

Effects of long-time DC bias on D2O- and D2/N2-annealed BST thin films

Effects of long time dc bias on both D2O- and D2-annealed BST thin films were investigated by secondary ion mass spectrometry (SIMS) analysis and electrical measurements before and after bias stressing. Bias conditions were sufficient to cause the degradation of (1) subsequently-measured current density-voltage characteristics and (2) a significant positive shift of the capacitance-voltage curve along the voltage axis. This latter effect may be attributed to the asymmetric space charge distribution in the BST thin film after bias stressing or, possibly, to changes in the interface state density. No significant deuterium motion was observed in D2O-annealed capacitors biased at an elevated temperature or in D2/N2-annealed capacitors biased at room temperature in high electric fields (∼3.5 × 107 V/m) for more than 8 hours. The small values of the Di• mobility which were inferred from the SIMS results are consistent with recent data on the kinetics of deuterium incorporation in and removal from similar BST thin films.

Effects of stage of harvest on the protein value of fresh lucerne for ruminants.

The ruminal degradation of dry matter (DM) and crude protein (CP) and the intestinal availability of CP of four fresh lucerne (Medicago sativa L.) samples, corresponding to a 3rd growing cycle and harvested at 2-week intervals, were determined. Rumen degradability, measured by the nylon bag technique, and rumen outflow rates were determined on three rumen-cannulated wethers. Intestinal digestibility was determined by the mobile bag technique on three duodenal fistulated wethers. Both groups of animals were fed a 2:1 lucerne hay to concentrate diet at an intake level of 40 g DM x kg(-1) BW0.75. The effective degradability (ED) of DM decreased with maturity in linear and quadratic form, as a consequence of a decrease in the soluble fraction and a similar increase in the undegradable materials. The resultant values were 0.795, 0.661, 0.600, and 0.576 for harvests at 2, 4, 6, and 8 weeks. The ED of CP showed the same trend. However, the variations (values of 0.896, 0.832, 0.791, and 0.817, respectively), were moderate and mainly due to the reduction of the proportion of soluble CP. The intestinal digestibility of CP of all samples showed a downward trend with the increase in the ruminal incubation time, as modelled according to a logistic function. The undegraded CP digested in the gut (Di) and therefore the effective intestinal digestibility (EID) were derived from this function according to the rumen outflow of undegraded CP. The effects of maturity on the mean values of Di, expressed as a proportion of the original CP content, were the opposite of those recorded for the ED of CP. These values were 0.067, 0.102, 0.115, and 0.089 for samples harvested at 2, 4, 6, and 8 weeks, respectively. Nevertheless, when Di was expressed as g CP x kg(-1) DM, these values (18.0, 17.4, 17.1, and 14.3, respectively) decreased in linear form. The same trend was observed for EID values, which represent 0.641, 0.609, 0.549, and 0.488, respectively. The change of the digestion site produced by the reduction of ED of CP was also associated with an increase in the undigested CP (values of 0.037, 0.066, 0.094, and 0.094, at the four harvesting times).

Fractal dimensions of individual flocs and floc populations in streams

The fractal dimension of an individual floc is a measure of the complexity of its external shape. Fractal dimensions can also be used to characterize floc populations, in which case the fractal dimension indicates how the shape of the smaller flocs relates to that of the larger flocs. The objective of this study is to compare the fractal dimensions of floc populations with those of individual flocs, and to evaluate how well both indicate contributions of sediment sources and reflect the nature and extent of flocculation in streams. Suspended solids were collected prior to and during snowmelt at upstream and downstream sites in two southern Ontario streams with contrasting riparian zones. An image analysis system was used to determine area, longest axis and perimeter of flocs. The area–perimeter relationship was used to calculate the fractal dimension, D, that characterizes the floc population. For each sample, the fractal dimension, Di , of the 28 to 30 largest individual flocs was determined from the perimeter–step-length relationship. Prior to snowmelt, the mean value of Di ranged from 1·19 (Cedar Creek, downstream) to 1·22 (Strawberry Creek, upstream and downstream). A comparison of the means using t-tests indicates that most samples on this day had comparable mean values of Di . During snowmelt, there was no significant change in the mean value of Di at the Cedar Creek sites. In contrast, for Strawberry Creek the mean value of Di at both sites increased significantly, from 1·22 prior to snowmelt to 1·34 during snowmelt. This increase reflects the contribution of sediment-laden overland flow to the sediment load. At three of the sampling sites, the increase in fractal dimensions was accompanied by a decreases in effective particle size, which can be explained by an increase in bed shear stress. A comparison of fractal dimensions of individual flocs in a sample with the fractal dimensions of the floc populations indicates that both fractal dimensions provide similar information about the temporal changes in sediment source contributions, about the contrasting effectiveness of the riparian buffer zones in the two basins, and about the hydraulic conditions in the streams. Nevertheless, determining the individual fractal dimensions of a set of large flocs in a sample is very time consuming. Using fractal dimensions of floc populations is therefore the preferred method to characterize suspended matter. Copyright © 2000 John Wiley & Sons, Ltd.

Investigation of the mass dependence of self-diffusion coefficients by molecular dynamics calculations: binary and ternary isotopic mixtures of atoms

Extensive molecular dynamics calculations have been used to study for the first time systematically the dependence of the self-diffusion coefficients Di (i = 1, 2, 3) in binary and ternary atomic isotopic mixtures on the particle mass ratios m*2 = m 2/m 1 and m*3 = m 3/m 1 at different reduced temperatures T* and reduced particle number densities n*, using a Lennard-Jones 12-6 potential and a hard-soft-spheres potential. In addition, the dependence of Di values of binary mixtures on the mole fraction x 1 = 1—x 2 was also investigated for some thermodynamic states. The calculated values of Di can be represented quantitatively by exponential estimates of the form Di = D* i (m*2)ex i in the case of binary mixtures and Di = D 0 i (m*2)ex i (m 3)ext i in the case of ternary mixtures. D 0 i are the self-diffusion coefficients in reference mixtures of mass ratios m*2 = m*3 = 1. The dependence of the exponents ex i (m*2, T*, n*, x 1) of binary mixtures on m*2, T*, n*, and x 1 and the dependence of the exponents ext i (m*2, m*3, n*) of equimolar ternary mixtures at T* = 1.8 on the exponents ex i of the constituent binary mixtures and on m*2, m*3, and n* are discussed.

Bond strengths of transition metal diatomics: Zr2, YCo, YNi, ZrCo, ZrNi, NbCo, and NbNi

The observation of an abrupt predissociation threshold in an extremely congested electronic spectrum has been used to measure the bond dissociation energies of the mixed early-late transition metal molecules YCo, YNi, ZrCo, ZrNi, NbCo, and NbNi. In these systems it is argued that predissociation occurs as soon as the ground separated atom limit is exceeded, providing values of Di(YCo) = 2.591 f 0.001 eV, Di(YNi) = 2.904 f 0.001 eV, D:(ZrCo) = 3.137 f 0.001 eV, Di(ZrNi) = 2.861 f 0.001 eV, Di(NbCo) = 2.729 f 0.001 eV, and Di(NbNi) = 2.780 f 0.001 eV. In addition, the bond strength of diatomic zirconium has been measured as Di(Zr,) = 3.052 f 0.001 eV. A discussion of the chemical bonding in the mixed early-late transition metal dimers and Zr1 is presented, based on the measured bond energies of these species. I. Introduction The chemical bonding between transition metal atoms is an area of interest to many different branches of chemistry, including metallurgy, surface science, and metal cluster chemistry. Unraveling the details of the complicated electronic structure in these metallic species is an ongoing process pursued through both experimental1.2 and theoreticaP4 avenues. From this research it is already clear that several distinct factors combine to determine thestrength and character of the chemical bond between transition metal atoms. One such factor is the loss of exchange energy which occurs upon formation of d-electron bonds, thereby reducing the strength of the chemical bonding. This is illustrated in the example of Ti2,5 where exchange effects favor the 4sui3d~:3du:3d6:, 3As,, state as a candidate for the ground state, while bonding considerations favor the 4sui3d?r~3du~, IZ; state. In Ti2 the balance between exchange effects and chemical bonding is so delicate that ab initio theory is incapable of determining which possibility is the ground state.5 Experimentally it is found that exchange effects dominate in Tiz, leading to an X 3$,, ground state.6 In the isovalent Zr2 molecule, however, the larger d-orbitals favor bond formation, leading to a strong theoretical prediction of a '2: ground Thus, to understand the bonding in the diatomic transition metals the competing effects of exchange and chemical bonding must be carefully considered.

Diurnal sleep study for sleep related breathing disorders--the utility of nasendoscopic diurnal polysomnography using diazepam

Twenty two patients with obstructive sleep apnea syndrome were examined by nocturnal polysomnography (n-PSG), and the obstructive sites in the upper airway were observed by nasendoscopic diurnal polysomnography using diazepam (n-d-PSGD). The types of apnea were divided into three groups according to the obstructive sites in the upper airway: soft palate apnea, tongue base apnea, and combined type apnea. Among the 22 patients, there were 17 soft palate apneas, 3 tongue base apneas and 2 combined type apneas. All patients underwent uvulopalatopharyngoplasty (UPPP). Preoperative values of AI, AR, DI and mean sleep SaO2 were 37.2, 24.5%, 31.4 and 92.5%, and the postoperative values were 10.4, 7.3%, 6.8 and 94.8%, respectively. Criteria were established to define UPPP responders, as follows: 50% or more reduction in AI and postoperative AI less than 20. The overall improvement rate was 81.0%. The improvement rates for soft palate apnea, combined type apnea and tongue base apnea were 93.8%, 50.0%, and 0%, respectively. In 15 of the 22 patients, measurements of mesopharyngeal and esophageal pressures were performed simultaneously with n-d-PSGD. In these 15 patients, 12 soft palate apneas, 2 combined type apneas and 3 tongue base apneas were observed with n-d-PSGD, while 7 soft palate apneas, 3 combined type apneas and 5 tongue base apneas were detected by measuring the pressures. The results of these two methods concurred in only nine of fifteen patients. It was suspected that the obstructive sites in the upper airway were identified by tissues with n-d-PSGD, but by region with the pressure measuring method. It was suggested that UPPP is the most suitable treatment for patients with soft palate type apnea, without pathologic obesity. n-d-PSGD is a useful method of evaluating respiratory status during sleep, can be performed in a few hours, and can simultaneously identify the obstructive site in the upper airway, so as to allow treatment planning.

Ternary diffusion: The (2~D) matrix of an ideal solid solution

The elements (~Dik3) of the (2~D) matrix of an interdiffusing ideal ternary solid solution have been determined for Manning’s random alloy model, and the relationships among the elements and the tracer diffusion coefficients (Di*’s) of the atom species have been examined. It is shown that for physically realistic choices of tracer diffusion coefficients a quasi-linear relationship exists between the ~Dik3 of the ith atom species and its atom fraction over the entire composition triangle. It is also, shown that a ~Dii3 diagonal element will never be negative for any physically realistic values of the Di*’s. Finally, the implications of the equality ~D223 = ~D223 are demonstrated.

The Discomfort-Index in Thessaloniki, Greece

Many investigators have tried to express the influence of climatic parameters upon man. In this paper, for the same purpose, we make use of the “Discomfort Index” (DI). [DI = 0.4 (Ta + Twb) + 4.8] as it has been introduced by THOM (1959). We study the mean diurnal variation of DI on the base of mean hourly values of Ta and Twb for the 1950–75 period in Thessaloniki-Greece and for the warm season only (May–September). The frequencies of hourly and daily values of DI are studied and mean and extreme monthly values are also given. Regarding the need of the use of climatization in Thessaloniki (DI >24) we found quite increased percentages only for the months: July and August.