Carry-over Factor Research Articles

Experimental Assessment of Correlative Approaches for the Prediction of Leakage Flow through Labyrinth Seals

Simple analytical models can be employed to estimate the leakage mass flow rate from labyrinth seals, resulting in a quick procedure, well suited for the early design process. Different formulas were proposed by many authors during the past decades and most of them employ a carry-over factor and a flow coefficient to predict the mass flow rate across the clearance area. The present work aims to compare the analytical prediction with the results of an experimental campaign. The experimental results were retrieved from a dedicated test rig for both a straight-through and a stepped labyrinth seal. Hence, for each seal, the effect of the clearance size, the Reynolds number and the pressure ratio has been investigated. Starting from the experimental required inputs, six different correlations are considered, with both direct and indirect methods. The results are shown as a function of pressure ratio and clearance gap. Despite some differences in the comparison, and most of the used correlation underestimate the measured mass flow rate, some general trends and guidelines can be highlighted.

Exposure to Low Zearalenone Doses and Changes in the Homeostasis and Concentrations of Endogenous Hormones in Selected Steroid-Sensitive Tissues in Pre-Pubertal Gilts.

This study was undertaken to analyze whether prolonged exposure to low-dose zearalenone (ZEN) mycotoxicosis affects the concentrations of ZEN, α-zearalenol (α-ZEL), and β-zearalenol (β-ZEL) in selected reproductive system tissues (ovaries, uterine horn-ovarian and uterine sections, and the middle part of the cervix), the hypothalamus, and pituitary gland, or the concentrations of selected steroid hormones in pre-pubertal gilts. For 42 days, gilts were administered per os different ZEN doses (MABEL dose [5 µg/kg BW], the highest NOAEL dose [10 µg/kg BW], and the lowest LOAEL dose [15 µg/kg BW]). Tissue samples were collected on days seven, twenty-one, and forty-two of exposure to ZEN (exposure days D1, D2, and D3, respectively). Blood for the analyses of estradiol and progesterone concentrations was collected in vivo on six dates at seven-day intervals (on analytical dates D1-D6). The analyses revealed that both ZEN and its metabolites were accumulated in the examined tissues. On successive analytical dates, the rate of mycotoxin accumulation in the studied tissues decreased gradually by 50% and proportionally to the administered ZEN dose. A hierarchical visualization revealed that values of the carry-over factor (CF) were highest on exposure day D2. In most groups and on most exposure days, the highest CF values were found in the middle part of the cervix, followed by the ovaries, both sections of the uterine horn, and the hypothalamus. These results suggest that ZEN, α-ZEL, and β-ZEL were deposited in all analyzed tissues despite exposure to very low ZEN doses. The presence of these undesirable compounds in the examined tissues can inhibit the somatic development of the reproductive system and compromise neuroendocrine coordination of reproductive competence in pre-pubertal gilts.

Correlations between Low Doses of Zearalenone, Its Carryover Factor and Estrogen Receptor Expression in Different Segments of the Intestines in Pre-Pubertal Gilts-A Study Protocol.

Plant materials can be contaminated with Fusarium mycotoxins and their derivatives, whose toxic effects on humans and animals may remain subclinical. Zearalenone (ZEN), a low-molecular-weight compound, is produced by molds in crop plants as a secondary metabolite. The objective of this study will be to analyze the in vivo correlations between very low monotonic doses of ZEN (5, 10, and 15 μg ZEN/kg body weight—BW for 42 days) and the carryover of this mycotoxin and its selected metabolites from the intestinal contents to the intestinal walls, the mRNA expression of estrogen receptor alfa (ERα) and estrogen receptor beta (ERβ) genes, and the mRNA expression of genes modulating selected colon enzymes (CYP1A1 and GSTP1) in the intestinal mucosa of pre-pubertal gilts. An in vivo experiment will be performed on 60 clinically healthy animals with initial BW of 14.5 ± 2 kg. The gilts will be randomly divided into a control group (group C, n = 15) and three experimental groups (group ZEN5, group ZEN10, and group ZEN15; n = 15). Group ZEN5 will be administered per os 5 μg ZEN/kg BW (MABEL), group ZEN10—10 μg ZEN/kg BW (NOAEL), and group ZEN15—15 µg ZEN/kg BW (low LOAEL). In each group, five animals will be euthanized on analytical dates 1 (exposure day 7), 2 (exposure day 21), and 3 (exposure day 42). Samples for in vitro analyses will be collected from an intestinal segment resected from the following regions: the third (horizontal) part of the duodenum, jejunum, ileum, cecum, ascending colon, transverse colon, and descending colon. The experimental material will be collected under special conditions, and it will be transported to specialist laboratories where samples will be obtained for further analyses.

Sustainable efficiency evaluation of regional state-level technology business incubating service systems in China: A dynamic two-stage slacks-based measure approach

Although the promotion of technology business incubators (TBIs) has been regarded as an effective strategy utilized by governments to facilitate technology innovation and sustainable economic growth, few studies have considered the network structure of TBIs when measuring their operational performance. In this study, we first propose a dynamic two-stage slacks-based measure model to assess the sustainable efficiency of incubators by decomposing the operational process into investment attraction stage and incubation stage. Within this framework, we treat incubating fund and new entrants as intermediate products, and regard the number of incubating enterprises as an undesirable output of the incubation stage to capture the carry-over effect between two successive periods. We then introduce the definitions of the period, stage and period stage efficiencies. The proposed method is employed to estimate the operational performance of China’s regional state-level technology business incubating service systems during 2013–2017. The results show that the negligence of the dynamic effect of the typical carry-over factor may lead to the underestimation of the incubating service systems’ overall efficiency as well as the efficiency of the incubation stage. The relatively lower incubation efficiency is the main reason for the inefficiency of Chinese technology business incubating service system. Moreover, significant geographic disparities in efficiencies among regions are observed. The western area enjoys the best performance, followed by the eastern area, while the central area performs the worst. We further explore the influencing factors on the efficiencies of incubating service systems and find that human capital is conducive to the improvement in the efficiencies of the two sub-stages. However, government support and technology progress contribute significantly to the investment attraction stage, while foreign direct investment has a positive effect only on the incubation stage. Finally, some useful policy implications are achieved.

Deoxynivalenol-3-sulphate is the major metabolite of dietary deoxynivalenol in eggs of laying hens

Previous studies reported very low carry-over of dietary deoxynivalenol (DON) into eggs of laying hens. However, recent studies showed that DON is extensively metabolised to DON-3-sulphate (DON-3S) in chickens. We therefore hypothesised that DON-3S might also be a major DON metabolite in eggs of laying hens fed with DON contaminated diet. The aim of the work was to develop, validate and apply an LC-MS/MS based method for determination of DON, deepoxy-DON (DOM), DON-3S, and DOM-3-sulphate (DOM-3S) in freeze-dried eggs of laying hens. Laying hens were allocated to three treatment groups (negative control (NC); DON low (3.8 mg/kg DON in feed); DON high (7.5 mg/kg DON in feed)) and eggs were collected in the 5th, 7th and 10th week of the trial. DON-3S was identified as the major DON metabolite in eggs for the first time with average concentrations in fresh eggs <0.74 ng/g in the NC, 4.4-6.4 ng/g in the DON low group and 7.9-9.7 ng/g in the DON high group. DON-3S was also the major DON metabolite in chicken plasma, with average concentrations of 6.8±4.1 and 10±7 ng/ml in the DON low and DON high group, respectively. Experiments with intestinal explants indicated that DON-3S is in part already formed in intestinal mucosa cells. Considering the carry-over factor of 0.001, the European guidance value of DON in poultry feed (5 mg/kg), the tolerable daily intake of DON (1 μg/kg body weight and day) and the average egg consumption in Europe (0.5 egg/day/person), there is no significant health risk due to carry-over of DON or DON-3S into eggs, even if theper se non-toxic metabolite DON-3S might be hydrolysed back to free DON in the gut of the egg consumer.

Corrigendum: Quantitative efficiency assessment based on the dynamic slack-based network data envelopment analysis for commercial banks in Ghana

Background: Gains in bank efficiency improvement have widely been regarded as one of the most effective and efficient means of ensuring sustainability of a financial system. Aim: This article proposes a relative dynamic two-stage network data envelopment analysis model for measurement of bank efficiency based on the slack-based measure. Setting: Twenty-seven banks in Ghana during the period of 2009–2014. Methods: By considering simultaneous processes within the framework of two-stage data envelopment analysis, the slack-based measure approach identifies the sources of inefficiency in the banks. Results: In the empirical analysis, non-performing loans are an undesirable output in one production process, which should also be treated as a carry-over factor; that is to say, some non-performing loans from the preceding year can be collected in the current year. The carry-over factors should be used to indicate the presence of performance gaps that exist in the banks. The proposed model was used to measure the efficiency of the 27 banks in Ghana during the period of 2009–2014. We also present useful suggestions for improvement in bank efficiency based on the empirical results. Conclusion: The 27 main commercial banks in Ghana are far from efficient. For all banks, the efficiency score in the second stage is much higher than that of the first stage. That means more attention should be paid to the first stage of production in order to increase the banks’ efficiency.

Quantitative efficiency assessment based on the dynamic slack-based network data envelopment analysis for commercial banks in Ghana

Background: Gains in bank efficiency improvement have widely been regarded as one of the most effective and efficient means of ensuring sustainability of a financial system. Aim: This article proposes a relative dynamic two-stage network data envelopment analysis model for measurement of bank efficiency based on the slack-based measure. Setting: Twenty-seven banks in Ghana during the period of 2009–2014. Methods: By considering simultaneous processes within the framework of two-stage data envelopment analysis, the slack-based measure approach identifies the sources of inefficiency in the banks. Results: In the empirical analysis, non-performing loans are an undesirable output in one production process, which should also be treated as a carry-over factor; that is to say, some non-performing loans from the preceding year can be collected in the current year. The carry-over factors should be used to indicate the presence of performance gaps that exist in the banks. The proposed model was used to measure the efficiency of the 27 banks in Ghana during the period of 2009–2014. We also present useful suggestions for improvement in bank efficiency based on the empirical results. Conclusion: The 27 main commercial banks in Ghana are far from efficient. For all banks, the efficiency score in the second stage is much higher than that of the first stage. That means more attention should be paid to the first stage of production in order to increase the banks’ efficiency.

Analysis of Non-Prismatic Two-Way Post-Tensioned Slabs

Using a moment-area procedure to analyze slab-beam with step haunches, rotational stiffness, carry over, and fixed-end moments of a flat slab are formulated for flat slabs with capitals and/or drop panels. Design factors derived are represented in graphical tables and may be used in the Equivalent Frame Method (EFM) for analyzing and designing two-way post-tensioned slabs. Both of equivalent prestressing loads: a point load and/or a concentrated moment are evaluated for the stiffer column-slab conjunction region due to tensioning prestressing tendons. The results clarify this prestressing equivalent load behavior, and provide a comprehensive basis of EFM for flat slabs. Compared to a prismatic member, a stiffer column-slab joint region increases the stiffness and carryover factor, and influences fixed-end moment of slab under gravity and prestressing loads. The expressions derived for design is available both hand-calculation and computer-aided program. A calculation example is given to illustrate the use of current expressions and existing tables and chart.

Zearalenone and its metabolites in the tissues of female wild boars exposed per os to mycotoxins

The study was performed on 18 clinically healthy female wild boars with initial body weight of 35 ± 2 kg. The animals were divided into two experimental groups (group I and group II) and one control group (group C) of 6 female wild boars per group. Group I animals were administered per os pure zearalenone (ZEN) at 150 μg/kg BW every two months for 7 subsequent days, whereas group II animals received feed naturally contaminated with ZEN at 50 μg/kg BW/day. Female wild boars were exposed to ZEN over a period of 1 year. Control group animals were fed a placebo. Tissue samples (dorsal muscles, left lobe of liver, left kidney, spleen, apical part of the cardiac muscle, cranial lobe of lung, left ovary, central part of the left horn of the uterus) were collected on the last day of the experiment within 3 min after slaughter. In group I, the highest ZEN levels were noted in the spleen (19.813 ng/g), cardiac muscle (18.105 ng/g) and kidneys (14.555 ng/g). In group II, the highest concentrations of ZEN were observed in muscle tissue (12.033 ng/g), uterus (10.821 ng/g) and kidneys (10.463 ng/g). The highest values of the carry-over factor were noted in the same tissues. In the examined female wild boars, per os exposure to natural sources of the parent substance or a combination of ZEN and its metabolites led to different concentrations of ZEN in the analyzed tissues. Zearalenone concentrations were compatible with CF values in both experimental groups.

Zearalenone in the Intestinal Tissues of Immature Gilts Exposed per os to Mycotoxins.

Zearalenone and its metabolites, α-zearalenol and β-zearalenol, demonstrate estradiol-like activity and disrupt physiological functions in animals. This article evaluates the carryover of zearalenone and its selected metabolites from the digesta to intestinal walls (along the entire intestines) in pre-pubertal gilts exposed to low doses of zearalenone over long periods of time. The term “carryover” describes the transfer of mycotoxins from feed to edible tissues, and it was used to assess the risk of mycotoxin exposure for consumers. The experimental gilts with body weight of up to 25 kg were per os administered zearalenone at a daily dose of 40 μg/kg BW (Group E, n = 18) or placebo (Group C, n = 21) over a period of 42 days. In the first weeks of exposure, the highest values of the carryover factor were noted in the duodenum and the jejunum. In animals receiving pure zearalenone, the presence of metabolites was not determined in intestinal tissues. In the last three weeks of the experiment, very high values of the carryover factor were observed in the duodenum and the descending colon. The results of the study indicate that in animals exposed to subclinical doses of zearalenone, the carryover factor could be determined by the distribution and expression of estrogen receptor beta.

CFD analysis of vapor flow and design improvement in MED evaporation chamber

This paper presents the Computational Fluid Dynamics (CFD) analysis of the vapor flow inside the Evaporation Chamber (EC) of a two-effect Multi-Effect Distillation (MED) unit. The study is part of the EU–Egypt funded project Multipurpose Applications by Thermodynamics Solar. The numerical analysis investigates the effect of velocity variations on the EC’s carryover factor and demister pressure drop for different separation baffle configurations. The trajectory of liquid droplets was calculated using Lagrange approach. The computational model was verified by comparing the predicated results (vapor pressure drop through the demister and separation efficiency) with those obtained from published data, with good agreement. At the design inlet vapor velocity of 3.3 m/s, a new baffle configuration is presented and is characterized by the best performance among the other configurations. This new baffle configuration shows a minimum carryover factor of 0.097 with a reasonable demister pressure drop less than 13.4% of the originally designed one. The study could be considered a benchmark and a helpful guideline for future designs of MED-EC.

Improved Moment Distribution Method and its Application

Change the general idea of the moment distribution method to analyze problems,not repeat fixed and relax joints to achieve a balance moment, but by the correction of the bending stiffness,deduced the moment carryover factor,moment once distributed and transferred twice you can get the moment exact solution.. Particularly suitable for the calculation of continuous beam internal forces and determination of envelope diagram and the influence lines of beam.

Shear and bending flexibility in closed-form moment solutions for continuous beams and bridge structures

Shear deformations can affect final member-end-moments for statically indeterminate continuous beams and frame structures, though for typical civil engineering structures their effect is small and moments can be based on flexural deformations only. When a member is deep relative to span length, however, shear deformations should be considered in the analysis. This can be included in the stiffness method and in a modified form of moment distribution where the carry-over factor is less than one-half due to the added flexibility from shear. In a prior paper the first author presented a new approach for solving statically indeterminate beams and bridge frames, with final end moments given in closed-form expressions. The advantages of this new approach are that no simultaneous equations are required as in the stiffness method, moments are not distributed back and forth as in moment distribution, and manual calculations may be used which give exact results for as many spans as desired. While only flexural deformations were considered in the original paper, this paper presents a closed-form approach that has been modified to include shear deformations. Final expressions are given for continuous beams and bridge frames, providing exact member-end-moments that match results from the stiffness method when shear deformations are included in the analysis.

Carry-over of Fusarium toxins (deoxynivalenol and zearalenone) from naturally contaminated wheat to pigs

The frequent contamination of grain with the Fusarium toxins, deoxynivalenol (DON) and zearalenone (ZON), is an important issue in animal and human nutrition. However, data on the exposure of humans to these toxins through consumption of animal tissues exposed to Fusarium toxins (carry-over) are fragmentary. Therefore, residues of DON, ZON and their metabolites were determined in tissues and body fluids of pigs (female and castrated male) from a fattening trial. Pigs were fed a control (n = 6, 0.24 mg DON and 0.009 mg ZON per kg diet as fed) or a Fusarium toxin-contaminated diet (n = 12, 6.68 mg DON and 0.056 mg ZON per kg diet as fed) either ad libitum or for restrictive consumption for 12 weeks. After slaughter (96.3 ± 11.6 kg live weight), the concentrations of DON and its metabolite, de-epoxy-DON, were measured in serum, bile, liver, kidney, musculus longissimus and back fat, while ZON and its metabolites, α- and β-zearalenol (α-/β-ZOL), were determined in serum, bile and liver. The mean carry-over factor of DON + de-epoxy-DON, defined as the concentration of both substances in the tissue/fluid divided by the DON concentration in the diet, for all pigs decreased from bile (0.1046 ± 0.0653) ≫ kidney (0.0151 ± 0.0070) > liver (0.0057 ± 0.0043) > serum (0.0023 ± 0.0018) > muscle (0.0016 ± 0.0016) ≫ back fat (0.0002 ± 0.0004). The time interval between the end of feeding and slaughter had no consistent effect on DON + de-epoxy-DON concentrations in the analysed specimen of Fusarium toxin-exposed pigs fed restrictively. No transfer of ZON and its metabolites could be observed into serum of pigs, while the mean carry-over factors of ZON + α-ZOL + β-ZOL were 0.0094 ± 0.0123 and 4.0 ± 2.2 for liver and bile, respectively. Therefore, it can be concluded that serum is a reliable indicator for DON exposure, but an inappropriate parameter to deduce ZON exposure, which is better represented by bile concentration of ZON + α-ZOL + β-ZOL. However, the exposure risk to humans by consumption of edible tissues of animals exposed to Fusarium toxins is negligible compared to the direct consumption of grain-based food.

Wing-body carryover for noncircular missiles

)9 the wing-body carryover factor due to body upwash on an undeflected wing, and wing center of pressure (CP) are investigated for unbanked, supersonic missiles with square and triangular fuselage cross sections at low angles of attack. The parametric effects of Mach number, wing leading-edge sweep back angle, angle of attack, and body cross-sectional shape on Kw(B) and wing CP were numerically examined. The calculations were performed using a spatial marching Euler code ZEUS. Predicted KW(B) results were compared to slender-body theory values historically used for preliminary missile design. Computed KW(B) and wing CP results were found to exhibit sensitivity to Mach number, wing leading-edge sweep angle, and body cross-sectional shape. Euler Kw(B) and wing CP values generally compare favorably to slender-body theory predictions in trend, but differ in magnitude by up to 15%. ZEUS predictions of kw(B)> the wing-body interference factor for an all-moving control surface, are also presented for square fuselage cross sections. All computed results are valid for missiles in the + orientation at small angles of attack and Mach numbers from 2 to 4. Data are presented to extend the missile preliminary design data base for arbitrary cross-sectional bodies.

PCDD/PCDF in cow's milk in relation to their levels in grass and soil

Three surveys were conducted to better know the factors which influence the PCDD/PCDF levels in cow's milk. These investigations comprised analyses of cow's milk, soil and grass at different sampling sites. The results show that the contamination levels in soil do not influence the PCDD/PCDF levels in cow's milk as is often suspected. Even soil levels up to 30 pg I-TEq/g dry matter did not result in elevated PCDD/PCDF levels in cow's milk. On the other hand, with increasing levels in grass a tendency to slightly higher levels in milk could be observed. These data seem to indicate that the pathway air → grass → cow is more important than the pathway soil → grass → cow. Moreover, it became apparent that the carryover factors (COF) for PCDD/PCDF between grass and milk differ significantly dependent on the congeners. While 2,3,7,8-T 4CDD showed the highest carryover factor, OCDD was accumulated less by a factor of almost 40. The relative ratio of these factors for each congener concerned was very similar at all sampling sites. However, the absolute height differed to a certain degree. The results of these investigations demonstrate that it is inappropiate to establish maximum contamination limits for soil or grass based on toxic equivalents in order to reduce the PCDD/PCDF levels in cow's milk since the bioaccumulation of these contaminants is highly dependent on the congeners. Risk assessment should therefore be made on a congener specific basis so that the PCDD/PCDF transfer between the media soil → grass → cow or air → grass → cow is neither over- nor underestimated for each compartment.

Emission of bacteria from air humidifiers

Abstract An experimental study was undertaken to determine the emission of bacteria from two different types of air humidifier. In one of the humidifiers, which is of spray type, the air is humidified by very small droplets of finely dispersed water being sprayed by nozzles into the air stream. The other humidifier is of evaporative type, in which the air is humidified by water being evaporated from a humid contact body. The emission of bacteria from the humidifiers was studied by adding Pseudomonas aeruginosa to the humidifier water. In addition, the emission of bacteria was simulated by metering polystyrene particles with a diameter of 2 μm into the humidifier water. The carry-over factor, defined as the ratio of the bacteria concentration in the humidified air to the bacteria concentration in the humidifier water, was found to be about 10−7 for the spray-type humidifier and about 5·10−10 for the evaporative humidifier of standard design. A modified evaporative humidifier was found to have a carry-over actor of less than 5·10−12 when tested with particles.

Studies on automated flameless atomic absorption spectrometry

A new device for automated sample injection in flameless AAS with graphite tubes had been investigated. Using solutions of Cd, Pb, Cu, and Ni the attainable precision, the carry-over factor by additional experiments with 89Sr, the lifetime of commercially available graphite tubes as well as the influence of some selected matrix types and a pyrolytic coating on the surface of the graphite tubes upon measured values had been studied. The results of these studies together with the hereby resulting advantages of the system and possible future applications are discussed.

Natural frequencies of grillages in which torsion can develop

In a previous paper [1] grillages in which no torsion developed were analysed to find their natural frequencies. This paper is directed to the task of analysing similar grillages in which torsion in the members is present. To accommodate the torsional vibrations the terms “dynamic torsional stiffness and carry-over factor” have been introduced and these are used in conjunction with the dynamic flexural functions of the previous paper.

Flexibility of Axially-Loaded Nonuniform Members

A simple scheme is devised to calculate the stiffness, carry-over factor, and fixed-end moment of nonuniform members under axial load either in tension or in compression. Based on the concept that the influence of the axial load and the non-uniformity of the cross section may be accounted for separately, it permits rapid determination of these constants by using existing design aids. The results of this investigation strongly indicate that the proposed method can be expected to yield satisfactory results in most practical cases.