RH Treatment Research Articles

副孔を有するラバールノズルを用いたRH精錬

副孔を有するラバールノズルを用いたRH精錬

Effects of relative humidity during the last five days of incubation and brooding temperature on performance of broiler chicks from young broiler breeders

Broiler hatching eggs were subjected to one RH condition (53% RH) from 0 to 16 d and switched to one of three different RH conditions (43, 53, or 63%) from transfer at 16 d to pull time at 21.67 d of incubation. The broiler breeder ages were 27, 29, and 31 wk for Trial 1, and 26, 28, and 30 wk for Trial 2 in Experiment 1. For both trials, BW at hatch, BW at pull, hatch time, and chick weight loss between hatching and pull were measured. All unhatched eggs were opened and examined macroscopically. Experiment 2 was conducted using the chicks produced in Experiment 1. The chicks were immediately placed after pull and randomly distributed by sex into brooding pens by RH treatment in Trial 1, and by sex, RH, and brooding temperature in Trial 2. Two brooding conditions, warm and cool, were used in Trial 2. Body weight at placement, BW gain to 12 d, feed conversion, and mortality were recorded. There was no effect of RH treatment on fertile hatchability. Body weight at hatch, pull, and placement increased with hen age. Mortality was higher for the late-hatching chicks in the warm brooding conditions in Trials 1 and 2 of Experiment 2, whereas mortality was significantly greater for the early-hatching chicks and those chicks hatched at 43% RH under the cool-brooding temperature conditions. Relative humidity treatment had no effect on chick performance in the presence of warm brooding conditions. Warm brooding conditions improved BW gain to 12 d compared with cold brooding conditions. Overall, optimal chick performance was achieved at 53% RH. Chick quality problems that may be due to high or low RH during incubation can be ameliorated by proper brooding conditions.

Armazenamento refrigerado de uvas cvs. Tardia de Caxias e Dona Zilá

O objetivo deste trabalho foi avaliar condições de armazenamento sobre as características físico-químicas e organolépticas e tratamentos pós-colheita para o controle de podridões em uvas de mesa cvs. Tardia de Caxias e Dona Zilá. As condições de armazenamento testadas foram: -1,0°C, -0,5°C ou +0,5°C com 97% de umidade relativa (UR) e -0,5°C com 93% de UR. Os tratamentos pós-colheita para controle de podridões foram: cloreto de cálcio (CaCl2 - 0,5%) aplicado por imersão; dióxido de enxofre (SO2) aplicado semanalmente através de 4g de metabissulfito de sódio (Na2S2O5); CO2 (5kPa) durante todo o período de armazenamento e; tratamentos intermitentes com CO2 (20kPa), aplicados semanalmente durante 24 horas. O delineamento experimental foi o inteiramente casualizado com três repetições. As avaliações foram realizadas aos 35 dias de armazenamento e após dois dias de exposição desses frutos à temperatura ambiente (±20°C). As cultivares Tardia de Caxias e Dona Zilá não apresentaram sensibilidade à baixa temperatura de armazenamento. A umidade relativa de 97% diminuiu a perda de peso, atém de reduzir o escurecimento do ráquis e o degrane das bagas. O tratamento pós-colheita com CaCl2 causou danos à epiderme, aumentando as podridões. O SO2 não influenciou a incidência de podridões. Já a utilização de altas concentrações de CO2 diminuiu ligeiramente as perdas por podridões. As cvs. Tardia de Caxias e Dona Zilá possuem boa capacidade de armazenamento, podendo ser conservadas sob refrigeração na temperatura de -1,0°Ca + 0,5°C.

612 The Relationship of Pollen Development and Release to Fruit and Seed Production in Tomato Cultivars Exposed to Heat Stress at Varying Humidity Levels

Starting 2 weeks before anthesis of the first flower, tomato cultivars (Lycopersicon esculentum Mill.) differing in heat tolerance were exposed to mild heat stress (31/24 vs. 28/22 °C) at three levels of relative humidity (30%, 60%, and 90%) in controlled environment chambers at the Duke Univ. Phytotron. Pollen development in the anthers was followed cytologically, pollen release was measured at anthesis, and seed production and fruit weight were measured as fruit matured. Fruit and seed development were best at 60%RH and 28/22 °C and worst at 90% RH and 31/24. Seed development was poor at 31/24 °C at all humidity levels. It was also poor at 28/22 in the 90% RH treatment. Low relative humidity had a greater negtive effect on fruit and seed production and on cytological development in plants grown at high temperature. Pollen release was also reduced at 90% RH, with virtually no pollen released at 31/24 °C. Cytological examinations revealed developmental anomolies in pollen in some, but not all cultivars at 90% and 30% RH. Plant height was also affected by the treatments, with much taller plants in the high-temperature, high-humidity treatments.

Improvement of Castability and Quality of Continuously Cast Steel.

Thermodynamic fundamentals on the systems Fe-Al-O and Fe-Al-Ca-S-O being important to metallurgy of Ca-treated Al-killed steels are analysed and discussed. The formation of liquid Ca aluminates for the improvement of castability is pursued in view of the production of Ca-treated Al-killed steels. The "Liquid window" is theoretically analysed and experimentally investigated. The top slag is formed after tapping and its composition is fairly constant during ladle treatment for both with and without RH treatment, respectively. However, the top slag of the degassed heats shows a lower oxygen level compared to the non-degassed heats. It is found that there exists an "inclusion path" during the ladle treatment. The inclusion path for the heats with RH treatment considerably differs from that of the heats without RH treatment and it greatly influences the efficiency of Ca treatment.

Histochemical, Physiological, and Ultrastructural Changes in the Maize Embryo during Artificial Drying

When drying high moisture(450–500 g H2O kg−1 fw) Zea mays L. seeds, a preconditioning period of drying at low temperatures(PC) may prevent injury due to subsequent high temperature drying. We preconditioned maize seeds under four different environments(35°C / 35% RH, 35°C / 90% RH, 20°C / 35% RH, and 20°C / 90% RH) and determined the level of seed deterioration in terms of reserve stability, enzyme activity, respiration, and ultrastructural changes in the radicle meristem. During PC, respiration rates were significantly higher for the 35°C than the 20°C treatments; however, overall respiration during PC was considerably lower than during germination. After 48 h of PC, amylase activity was present in all of the PC treatments with the highest levels and additional isozymes in the 35°C / 90% RH treatment. This treatment was also the only one in which we found degradation of starch grains in the histochemical analysis. During PC, transmission electron micrographs revealed migration of lipid bodies toward the cell wall and formation of protein bodies within vacuoles. Both of these processes were more likely to appear in those treatments that allowed higher rates of desiccation or in which the seeds were more mature (Harvest 2). Mitochondrial cristae were well differentiated with no evident impairment of their integrity in any of the PC treatments. Better seed quality was obtained when seed were preconditioned at moderate (35°C) temperature and low (35%) relative humidity. We conclude from these results that the positive effects of preconditioning may occur as a balance between metabolic and morphological processes resulting in high temperature desiccation tolerance, while minimizing the negative impact of the catabolic events such as degradation of starch grains and higher respiration rates.

Absorption of topdressed nitrogen by rice through mass flow under different relative humidities

To evaluate the contribution of mass flow to the absorption of topdressed N by paddy rice, a pot experiment was conducted under different rates of water uptake at the panicle formation stage. The rate of water uptake was !Dodified by using two different values of relative humidity (RH, 75% and 95%). Labelled N was used to determine the amount of absorbed fertilizer-derived N in the rice plants. The amount of ammonium N (NH4 +-N) in the floodwater was depleted within 48 h after topdressing (HAT) in all the treatments. The concentration of NH4 +-N in the soil solution decreased with depth in the top 0.03 m of soil. N in the soil solution from 0 to 0.03 m soil depth was almost depleted by 48 HAT. The percentage of fertilizer-derived N recovered by plants and the pattern of N accumulation were the same in all the RH treatments. However, in the course of the entire experiment, the amount of N absorbed through mass flow was larger in the 75% RH treatment during the first 48 h. Moreover, under 75% RH conditions, the percentage of topdressed N in the plants that was associated with N absorbed through mass flow was 78% at 48 HAT and 29% at 168 HAT. These values were significantly higher than -the previously reported values for basal N (2.5–6.3%). Therefore, it is concluded that the role of mass flow in N absorption is more significant for topdressed N than for basal N.

Circulation rate of liquid steel in RH degassers

Vacuum‐decarburization with the Ruhrstahl‐Heraeus process is used for the production of ultra‐low carbon steels. One important aspect of the RH process is the circulation of liquid steel between the degassing unit and the transport ladle. Thus, supervisory control of the RH treatment requires precise mathematical modelling of the circulation rate. In this work, a numerical model of the circulation flow is described in detail.This newly developed model as well as a frequently used semi‐empirical equation are compared with measured data. It is shown that the numerical model is in far better accordance with the measured data than the semi‐empirical equation. The numerical model is then applied to data of a conventional RH treatment. Special emphasis is put on the coupling of circulation rate and reaction rate. Both, circulation rate and reaction rate, are calculated as a function of time.

RH真空脱ガス装置における介在物除去機構

RH真空脱ガス装置における介在物除去機構

Effect of Humidity, Temperature, and Scarification during Storage on Seed Germination of Lupinus havardii and L. texensis

Lupinus havardii and L. texensis are two commercially important species of lupines (bluebonnets) in Texas. There is no current information for the storage requirements of these two bluebonnet species seeds. A study was undertaken to examine the effects of relative humidity, temperature, and scarification on seed germinability. Seeds of the two bluebonnet species were stored under five relative humidity treatments (11%, 23%, 52%, 75%, and 95%) and two temperature treatments (3°C or 22°C) either scarified or nonscarified in factorial combination. Seed samples were removed monthly. Nonscarified seed were scarified and all seed were placed in a seed germination chamber and germinated in petri dishes containing moistened filter paper. All samples of seed stored under 95% relative humidity were lost to seed-borne contamination. Germinability of scarified seed of both species decreased within 5 months in the 22°C/75% RH treatment. Other treatments had no effect on germinability during 7 months of seed storage.

Surface characteristics, reliability, and failure mechanisms of tin/lead, copper, and gold metallizations

In this paper, surface characteristics, microstructure, reliability and failure mechanisms of tin/lead, copper and gold metallizations for conductive adhesive joining have been studied. Electron spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy (AES) have been used to analyze Sn37Pb, copper and gold metallizations. The analyzes show that copper and nickel may be present as impurities on the gold plated surface. The tin and lead oxides present on the Sn37Pb plated surface were found to be 74 /spl Aring/ and 26 /spl Aring/, respectively. The microstructures were studied using scanning and transmission electron microscopy (SEM and TEM). The chemical analysis of the consisting compounds were analyzed using energy dispersive X-ray analysis (EDX). The conductive adhesive joints were exposed to constant humidity treatment at 85/spl deg/C, 85% RH up to 2000 h. The mechanical and electrical performance were measured using a shear tester and an Ohmmeter after various humidity treatment times. After the 85/spl deg/C/85% RH treatment, an increase in electrical resistance of the copper joints was found with increasing testing time due to the formation of Cu/sub 2/O. Also, there was a decrease in mechanical strength and an increase in electrical resistance due to oxidation of Pb. The best electrical performance was observed on the gold metallization after the constant humidity test.

The secondary refining technologies for improving the cleanliness of ultra-low carbon steel at Kwangyang Works

To improve the cleanliness of ultra-low carbon steel, several techniques concerning ladle slag control and RH treatment were adopted at Kwangyang Works. As a result, total oxygen in slab is reduced to about 9 to 12 ppm, and the rejected ratio in cold rolled coil is decreased.

Desulphurisation during RH treatment at Hoogovens Staal

For the production of calcium treated HSLA steel grades, it is important to produce steel with very low sulphur levels (maximum 50 ppm sulphur in the finished products).At Hoogovens Staal BOS No. 2, a method has been developed to desulphurize steel after the BOS process, using the RH-OB installation. In this new method, it is not necessary to install injection equipment.The result of this method is a very high hitting rate for steel grades with maximum 50 ppm sulphur.

The Successive Hydrogen Concentration Control in Molten Steel by Direct Hydrogen Measuring System.

Low hydrogen content in the steel is required to steels, such as special bar quality, crank-shaft, railway wheel, structural steel etc. By using the conventional hydrogen analyzer, quick response and necessary accuracy can not be obtained. Long time RH treatment was essential. Eventually, RH vessel life has been shorter. Therefore, dynamic-dehydrogenation model has been developed to attain both an optimum operation of RH-degasser and a security for dehydrogenation of hydrogen content after treatment. Followings are features of the dynamic dehydrogenation model:1) Prompt adjustment of dehydrogenation by using direct hydrogen measurement system.2) Correspondence to hydrogen pick-up from added alloys.3) The KH depends on many factors, for example, RH conditions, chemical component and other characteristics. It is well known that Q depends on the RH operating conditions.4) The KH clearly shows that maintenance of the snorkel diameter is important to keep the enough dehydrogenate rate. Also KH is decreased sharply in the low [H] region lower than 1 ppm.With this model, treatment time was reduced by 6 min and the hydrogen content was controlled within the accuracy of ±0.2 ppm.

In vitro hardening of red raspberry through CO2 enrichment and relative humidity reduction on sugar-free medium

Micropropagated shoots of red raspberry (Rubus idaeus L. ’Comet’) were rooted on modified Murashige-Skoog medium lacking sucrose, in specially constructed plexiglass chambers, under ambient (340 ± 20 ppm) or enriched (1500 ± 50 ppm) CO2 and ambient (ca. 100%) or reduced (90 ± 5%) relative humidity. Cultured plantlets were evaluated for their survival, rooting and relative vigor, leaf and root number, stem and root length, total leaf area, total fresh and dry weight, gas exchange rate, and stomatal features, prior to transplantation to soil and at intervals for 6 wk ex vitro. In vitro CO2 enrichment promoted plantlet growth, rooting and both the survival and early growth of transplants. CO2 enrichment increased stomatal aperture of plantlet leaves but did not apparently increase water stress at transplantation. Reduced in vitro RH did not affect plantlet growth but decreased stomatal apertures and stomatal index on leaves of cultured plantlets and promoted both the survival and early growth of transplants. In vitro CO2 and RH levels did not affect the photosynthetic rate of either plantlets or transplants. Only the stomata on leaves of plantlets from the ambient CO2 and reduced RH treatment were functional. Normal stomatal function was not observed in persistent leaves of transplants from the other treatments, even 2 wk after transplantation. In vitro CO2 enrichment acted synergistically with RH reduction in improving growth of plantlets both in vitro and ex vitro. Hardened red raspberry plantlets obtained through CO2 enrichment and RH reduction survived direct transfer to ambient greenhouse conditions without the necessity for specialized ex vitro acclimatization treatment. Key words: Acclimatization, growth analysis, photosynthesis, Rubus idaeus L., stomata, tissue culture

Fluid Flow in Ladle and Its Effect on Decarburization Rate in RH Degasser.

Theoretical and experimental studies were carried out to quantitatively understand the effect of fluid flow on the decarburization reaction rate in an RH degasser. Hydrodynamic calculations on fluid flow in the ladle were proved reasonable by a cold model experiment. The decarburization model in conjunction with the fluid flow by hydrodynamic calculations in the ladle made it clear that the decarburization rate obtained from this model was faster than that for perfectly mixed flow, and slower than that for plug flow when the same parameters were used for the calculations. The decarburization model enabled us to predict the concentration distribution of carbon in the ladle during an RH treatment. The maximum carbon content, which was found in the recirculating zone in the ladle, reached about twice the minimum value obtained in the region just below the down-leg. No dead zone existed which would disturb the decarburization rate in the process, and it was also made clear that the shape of ladle had little effect on the decarburization rate.

Survival of larvae of Boophilus annulatus, Boophilus microplus, and Boophilus hybrids (acari: ixodidae) in different temperature and humidity regimes in the laboratory

The survival period for larvae of Boophilus annulatus (Say), Boophilus microplus (Canestrini) and hybridized Boophilus ticks was determined by exposure to various combinations of temperature (20, 25, 30 and 35°C) and relative humidity (32, 63, 75, 84 and 97% RH) in the laboratory. Results indicated that within a given temperature and RH regime, there was no difference ( P > 0.05) in larval survival among the three species tested, indicating that these ticks respond similarly over a wide range of temperature and RH combinations. Larval survival in all three species was longest ( P < 0.05) at 20°C and either 84 or 97% RH. With each increase in temperature at the 84 and 97% RH treatment levels, there was a corresponding significant ( P < 0.05) decrease in larval survival. When the temperature reached 35°C at all humidities or when the RH was 63% or less at all temperatures, the mean larval survival period was 43 days or less in all cases and little difference ( P > 0.05) was observed among the treatment regimes included. Results suggest that at a RH of 75% and more, the temperature is the determining factor in larval survival, whereas at a RH of 63% and less the RH is the determining factor in larval survival, regardless of temperature.

RH真空脱ガス装置の取鍋内溶鋼流動と脱炭反応

Theoretical and experimental studies were carried out to quantitatively understand the effect of fluid flow on the decarburization reaction rate in an RH degasser. Hydrodynamic calculations on fluid flow in the ladle were proved reasonable by a cold model experiment. The decarburization model in conjunction with the fluid flow by hydrodynamic calculations in the ladle made it clear that the decarburization rate obtained from this model was faster than that for perfectly mixed flow, and slower than that for plug flow when the same parameters were used for the calculations. The decarburization model enabled us to predict the concentration distribution of carbon in the ladle during an RH treatment. The maximum carbon content, which was found in the recirculating zone in the ladle, reached about twice the minimum value obtained in the region just below the down-leg. No dead zone existed which would disturb the decarburization rate in the process, and it was also made clear that the shape of ladle had little effect on the decarburization rate.

底吹き転炉の精錬機能の拡大

Hot metal pretreatment system has recently established applicable to virtually all hot metal produced in Chiba Works. Several developments have been made for establishing an optimum and cost-efficient Q-BOP operations with dephosphorized metal. The main features of the developments are as follows : 1) Final dephosphorization in Q-BOP is possible by non slag-off blowing method with the use of only a slight amount of dolomite used for coating. By this method, reduction of lime consumption in Q-BOP is achieved. 2) By lowering oxygen flow rate at the final stage of blowing, excess oxidation of steel melt is prevented. Figures of ( T. Fe) in slag and [O] in steel at tapping are lowered by 4% and 100 ppm, respectively. 3) Newly introduced post combustion lance is effective for heat compensation and mouth skull melting. 4) Tapping temperature is successfully decreased by 26°C in manufacturing process of ultra low carbon steel with the aid of the development of KTB, the technology of oxygen blowing through top lance in the vacuum vessel. This technology is effective not only for heat compensation during RH treatment but also for enhancing a decarburization rate in higher carbon region.

高級鋼管および薄板における高純度鋼製造技術

Following purification technology for line pipes or cold sheets has been developed and put to practical use in some works of Nippon Steel Corporation. (1) Synthetic refining system of hot metal pretreatment, top and bottom blowing converter and multi-functional secondary refining, namely ladle injection under reduced pressure (V-KIP), flux injection during RH treatment (RH-Injection, RH-PB) are successfully in operation. Consequently final product of [P] ≤ 50 ppm, [S] ≤ 10 ppm and [H] ≤ 1.5 ppm can be stably produced. (2)Ar injection into RH vacuum vessel or DH snorkel and vacuum vessel drastically improved decarburization rate of ultra low carbon level.Technology of nitrogen removal during top and bottom blowing in converter and protection of molten steel from nitrogen adsorption between the end point of converter and casting have been operated. Consequently final product of [C] _??_ 10 ppm, [N] _??_ 10 ppm can be produced.