Relative Humdity Research Articles

Challenges for Ex Situ Conservation of Wild Bananas: Seeds Collected in Papua New Guinea Have Variable Levels of Desiccation Tolerance.

Ex situ seed conservation of banana crop wild relatives (Musa spp. L.), is constrained by critical knowledge gaps in their storage and germination behaviour. Additionally, challenges in collecting seeds from wild populations impact the quality of seed collections. It is, therefore, crucial to evaluate the viability of seeds from such collecting missions in order to improve the value of future seed collections. We evaluate the seed viability of 37 accessions of seven Musa species, collected from wild populations in Papua New Guinea, during two collecting missions. Seeds from one mission had already been stored in conventional storage (dried for four months at 15% relative humidity, 20 °C and stored for two months at 15% relative humdity, −20 °C), so a post-storage test was carried out. Seeds from the second mission were assessed freshly extracted and following desiccation. We used embryo rescue techniques to overcome the barrier of germinating in vivo Musa seeds. Seeds from the first mission had low viability (19 ± 27% mean and standard deviation) after storage for two months at 15% relative humidity and −20 °C. Musa balbisiana Colla seeds had significantly higher post-storage germination than other species (p < 0.01). Desiccation reduced germination of the seeds from the second collecting mission, from 84 ± 22% (at 16.7 ± 2.4% moisture content) to 36 ± 30% (at 2.4 ± 0.8% moisture content). There was considerable variation between and (to a lesser extent) within accessions, a proportion of individual seeds of all but one species (Musa ingens N.W.Simmonds) survived desiccation and sub-zero temperature storage. We identified that seeds from the basal end of the infructescence were less likely to be viable after storage (p < 0.001); and made morphological observations that identify seeds and infructescences with higher viability in relation to their developmental maturity. We highlight the need for research into seed eco-physiology of crop wild relatives in order to improve future collecting missions.

Practical Torso Cooling During Soccer-Specific Exercise in the Heat.

Precooling and midevent cooling of the torso using cooling vests can improve exercise performance in the heat with or without physiological changes; however, the effects of such cooling during intermittent exercise in the heat are unknown. To investigate the effects of torso cooling during intermittent exercise in the heat (35°C, 50% relative humdity) on sprint performance and the physiological and perceptual responses to the exercise. Crossover study. Walk-in environmental chamber. Ten non-heat-acclimated, male soccer players (age = 25 ± 2 years, height = 1.77 ± 0.06 m, mass = 72.9 ± 7.6 kg). Two 90-minute bouts of soccer-specific intermittent running in the heat: 1 trial with a cooling vest worn during the exercise and 1 trial without a cooling vest. Each trial comprised two 45-minute periods separated by approximately 15 minutes of seated rest in cool conditions (approximately 23°C, 50% relative humdity). Peak sprint speed, rectal temperature (Tr), mean-weighted skin temperature (Tsk), heart rate (HR), rating of perceived exertion (RPE), and thermal sensation (TS) were measured every 5 minutes. Peak sprint performance was largely unaffected by the cooling vest. The Tr, Tsk, HR, RPE, and TS were unaffected in the cooling-vest trial during the first 45 minutes, but Tr rose at a slower rate in the cooling-vest trial (0.026°C.min-1 ± 0.008°C.min-1) than in the no-vest trial (0.032°C.min-1 ± 0.009°C.min-1). During the second 45-minute period, Tr, Tr rate of rise, Tsk, RPE, and TS were lower in the cooling-vest trial (Hedges g range, 0.55-0.84), but mean HR was unaffected. Wearing a cooling vest during soccer-specific intermittent running in the heat reduced physiological and perceptual strain but did not increase peak sprint speed.

Leakage Current and Discharge Phenomenon of Outdoor Insulators

This paper descirbes leakage current characters and discharge phenomenon of outdoor insulators both in the lab and in the field. The results are hoped to be used for online monitoring of the contamination levels. The following contents are introduced in the paper: leakage current monitoring systems, relationships between leakage current and discharge phenomenon, flashover prediction methods and its applications in the field. The leakage current monitoring system is introduced firstly. Then the relationships between leakage current and discharge phenomenon for both suspension insulators and post insulators are presented based on the laboratory tests. A new parameter (I * ) that accounted for maximum leakage current (Ih) and different insulator shapes is introduced to estimate the flashover voltage for different kinds of pollutant layers when they are saturated with moisture. Meanwhile, the relationships between relative humdity (RH) and maximum leakage curren, altitude and maximum leakage current are investigated. With these results a flashover prediction method is developed. Ih measured in different relative humidity is converted to I * for the same contaminate layer when it is saturated with moisture. Then the flashover voltage is estimated by I * . Furthermore, an online leakage current monitoring results are analyzed. The relationships between leakage current characters in the field and ambient relative humidity are analyzed. The results show that although there are some differences between the leakage current in the field and in the lab because of some especially serve atmospheric conditions, the relationships are similar. Meanwhile, leakage current waveforms in different weather conditions are investigated. The waveforms of leakage current in the field are similar with those in the lab. The leakage current waveform that accounted for strong arc is found in the field. Finally, the contamination level of the field insulator is evaluated. The results corresponds well with the local condition.

Technique for the measurement of dimensional changes of natural microfibril materials under variable humidity environments

An algorithm was developed to analyze the dimensions of line scan data of step-shaped disconitunities acquired with an atomic force microscope. The effect of a number of AFM parameters on the quantitative imaging of step features was discussed. Quantitiative imaging using AFM was shown to be very reproducible as five successive scans of a standard step height grating produced less than 3% variation in measured parameters. A cellulose microfibril, called cellulose aggregate fibril (CAF), with dimensions of ∼50,000 nm × 2000 nm × 300 nm derived from papermaking fibers was scanned under cyclic relative humdity conditions with the relative humidity starting at 50% then raising to 80% followed by a decrease in the relative humidity to 28%. Changes in the width of the CAF were weakly correlated with changes in the relative humdity, while changes in the height and area of the CAF were positively correlated with the relative humdity. The length of the CAF was negatively correlated with the given relative humdity cycle. These findings have significant implications in paper dimensional stability and the engineering of cellulose micro and nano-fiber composites.

Factors controlling upper tropospheric relative humidity

Abstract. Factors controlling the distribution of relative humidity in the absence of clouds are examined, with special emphasis on relative humidity over ice (RHI) under upper tropospheric and lower stratospheric conditions. Variations of temperature are the key determinant for the distribution of RHI, followed by variations of the water vapor mixing ratio. Multiple humidity modes, generated by mixing of different air masses, may contribute to the overall distribution of RHI, in particular below ice saturation. The fraction of air that is supersaturated with respect to ice is mainly determined by the distribution of temperature. The nucleation of ice in cirrus clouds determines the highest relative humdity that can be measured outside of cirrus clouds. While vertical air motion and ice microphysics determine the slope of the distributions of RHI, as shown in a separate study companion (Haag et al., 2003), clouds are not required to explain the main features of the distributions of RHI below the ice nucleation threshold. Key words. Atmospheric composition and structure (pressure, density and temperature; troposphere – composition and chemistry; general or miscellaneous)

Erosion of SS41 steel by sand blasting

Erosion of SS41 steel by sand blasting, with abrasives of different particle sizes striking at different angles, was experimentally investigated under different environmental conditions. Experiments were conducted at temperatures of 25 °C, 35 °C, 45 °C, and 55 °C and at 50, 65, 80, and 95 pct relative humdity (RH). The surface morphology of the eroded area was studied. In addition to the target volume loss, the worn area and worn depths of the eroded material were investigated. Among the test temperatures, it was found that the temperature of 45 °C resulted in the lowest volume loss and worn area, but also in the deepest worn scar at nearly every attack angle. Among the test humdity conditions, the deepest worn scar occurred at a low attack angle (15 deg) for very low and high humidity conditions (RH = 50 and 95 pct), while it occurred at intermediate angles for intermediate humidity conditions (RH = 65 and 80 pct). If the applied pressure of the carrier gas and the total weight of the particles were constant, finer particles tended to result in more volume loss and deeper worn scars, with only a minor effect on the worn area.

A Comparison of Three Equilibrium Relative Humdity Measuring Devices

Three different types of equilibrium relative humidity measuring devices, capable of measuring the equilibrium relative humidity of a hygroscopic sample, were compared. The devices were: 1) a Container Hygrometer Apparatus, 2) a Dew Point Apparatus and 3) a Digital Hygrometer Apparatus. The devices were tested for accuracy of relative humidity measurement by generating atmospheres of known relative humidity in the sample compartments of the devices. The Digital Hygrometer Apparatus was found to be the device of choice for routine measurements, as it had acceptable accuracy over a wide range of humidites, and was easy-to-use. This device was used to measure the equilibrium relative humidity of a mixed-sugar tablet diluent at two different moisture contents. occur during compression, as indicated by the increase in drug release rate at lower porosities (see Figure 4).Heckle developed a first-order relationship between pressure and porosity (12), which can sometimes be used to ascertain the mechanism of consolidation (13,14). Compression of formulations containing Avicel did not yield linear Heckle plots. Similar results were obtained by other investigators (15-17). Heckle plots for Emdex and Fast Flo Lactose were linear (see figure 3). Effect of microcapsule percentageFor each excipient there seemed to be a limit to the amount of microcapsules which could be incorporated into the formulation and still produce acceptable tablets. Avicel allowed incorporation of a greater percentage of microcapsules without serious degradation of tablet performance or microcapsule control over drug release. The apparent superiority of Avicel over Bndex or Fast Flo Lactose in protecting microcapsules from possible damage during compression may be attributed to Avieel's excellent cempressibi1i ty.

Bonding amalgam to glass ionomer with PAA

Several considerations led to the hypothesis that a bond might be mediated between amalgam triturate and initially set glass ionomer (GI) by polyacrylic acid (PAA). Thirty samples (6 per group) of amalgam-bonded-to-glass ionomer were prepared by coating (without removal) the initially set glass ionomer suface with 40% PAA for 15, 30, 60, 90 or 120 s prior to amalgam condensation. Six samples of GI only (GO) were also prepared as a control group. All samples were stored at 37°C and 90±1% relative humdity for one week prior to shear testing. Mean shear strengths (MPa) for the groups were as follows: GO=4.12, 120 s=3.96, 90 s=3.25, 60 s=3.15, 30 s=098, and 15 s=0.56. The shear strengths of the bonded samples PAA-treated for 60 s or longer were not significantly different (p>0.05) from the shear strengths of the solid glass ionomer (GO) samples. Significantly weaker bonds (p<0.05) were formed in those groups PAA-treated for 30 s or less.

The effect of molasses on the evaporation and impaction of spray droplets

AbstractThe addition of 20% molasses to water did not reduce the rate of evaporation of water from spray droplets. The 20% molasses droplets evaporated at the same rate as water droplets until ca 20% of their volume was left. When sprayed under field conditions at 30% relative humdity (r.h.) the volume median diameter (v.m.d.) of the 20% molasses spray (132 μm) was larger than the v.m.d. of the water spray (116 μm) and more droplets smaller than 19 μm were captured on magnesium oxide slides than with the water spray. The addition of molasses improved the impaction efficiency of droplets by increasing their density, and increased the minimum size to which a given droplet could evaporate.

EFFECT OF N, P AND K ON SORGHUM CSH 5 HYBRID SEED CROP III. SEED STORABILITY

CSH 5 hybrid seeds obtained from the plants given 0. 100 and 200 kg/ha of N and 0, 50 and 100 kg/ha of P205 and K20 each were subjected to accelerated age ng at 40 +1°C and 95 per cent relative hum dity for seven days, Germination of aged seeds revealed that each of the nutrient at 100 kg/ha had significantly Improved the seed storability.

Gas diffusive conductance of sea-level hen eggs incubated at 2900 m altitude

Sea level hen eggs, selected for their shell conductance (water vapor conductance, H H 2O ), were incubated at a simulated high altitude, P b = 529 Torr , ca. 2900 m, at 72% relative humdity (rh) to prevent excessive water loss due to hypobaric condition; they were transferred to 150 m 18–24 h before measurements. Control eggs were incubated at 150 m, P b = 750 Torr, rh = 60% . In 8- to 18-day embryos, total CO diffusive conductance, G CO; embyronid body mass, BM; oxygen consumption, Ṁ O 2 ; blood hematocrit, Hct; hemoglobin concentration, [Hb]; and heart mass, HM, were measured. Total water loss was the same in both groups, 12% initial egg mass. However, the severe effects of high altitude: 72% mortality and 9% malformation, and reduced increases of BM and Ṁ O 2 , can be related partially to the strong hypocapnia, which resulted from the high shell conductance (G H 2O = 18.1 mg·(d·Torr) −1, and was superimposed on the hypoxia. G CO was reduced, while Hct, [Hb] and HM were not significantly affected. When measurements. were normalized to BM, Ṁ O 2 and G CO were identical in the two groups, whereas [Hb] and HM were higher at 2900 m (differential growth). Thus, during incubation, gas diffusive conductance appeared to depend on embryo development and did not adapt to altitude hypoxia. Compared with controls, G CO in high-altitude eggs actually decreased in proportion to BM growth.

Cytogenetics of Ticks (Acari: Ixodoidea): Chromosomes and Timing of Spermatogenesis in Amblyomma inornatum

low humidity adversely affected the hatching process but not the rate of embryonic development of eggs of the closely related Ophionyssus natricis (Gervais). Similar information for the northern fowl mite is not available. II. Effect of constant relative hum dity on the li of northern fowl mite e gs.* Very low humidity caused only a small decrease in egg hatch (74.2% hatch at 20% relative humidity). Thus, the effect of relative humidity on the hatching percentage was less marked than that of temperature (no hatch at 40 C). The effect of relative humidity on the incubation period of eggs of parasitic mites has been studied little. Changes in relative humidity did not seem to affect the incubation period of northern fowl mites (Combs and Lancaster, 1965, loc. cit.) or Ornithonyssus bacoti (Hirst) (Skaliy and Hayes, 1949, American Journal of Tropical Medicine 29: 759772), at least at optimal temperatures. Thus, under the conditions of the present experimental study, temperature was probably the chief factor influencing embryonic development.