Low Air Humidity Research Articles

Lycopene and beta carotene concentration in aril oil of gac (Momordica cochinchinensis Spreng) as influenced by aril-drying process and solvents extraction

The purpose of this study was to evaluate the lycopene and beta carotene concentration in aril oil of gac as influenced by extracting solvents and drying methods. The solvent extractions namely chloroform:methanol (2:1v/v), petroleum ether and hexane were evaluated for optimal extracting solvent of each carotenoid. Three different drying methods were used including hot-air (HA), low relative humidity air drying (LRH) and far-infrared radiation (FIR). The extracts of different solvents were exhibited to have different levels of lycopene and beta-carotene. Chloroform:methanol (2:1v/v) showed higher lycopene and beta-carotene content in aril oil (0.49 and 1.18mg/g) than that of fresh aril (0.045 and 0.009mg/g). Among the different drying methods, HA was found to provide the highest amount of lycopene (0.82mg/g DW) in the aril oil, followed by FIR (0.67mg/g DW) and LRH (0.56mg/g DW). Interestingly, HA dried aril oil had higher content of lycopene than that of control (fresh). However, processing methods are known to have variable effects on bioactive compounds of plant samples. Effects could vary from little or no change to significant losses, or even enhancement in antioxidant properties.

Optimized Drying of Kaprow Leaves for Industrial Production of Holy Basil Spice Powder

The present study investigated the changes in color, volatile compounds, total phenolic content, total flavonoid content, and antioxidant activity of two holy basil leaves (kaprow in Thai) Ocimum sanctum L. cultivars, kaprow khao and kaprow daeng, after three drying treatments, namely hot air (HA), low relative humidity air drying (LRH), and far-infrared radiation (FIR). Overall, HA dried showed a greater decrease in L values than did LRH and FIR dried for both kaprow cultivars. A significant decrease in total phenolic content (TPC), total flavonoid content (TFC), and ferric reducing antioxidant power (FRAP) was found in hot-air (HA) dried compared to fresh leaves, while TPC, TFC, and FRAP in LRH and FIR dried kaprow were significantly increased. Kaprow daeng and kaprow khao attributes represented by such compounds as β-caryophyllene, methyl eugenol, and eugenol were found to increase during drying. We found that eugenol was a major volatile compound ranging from 18% in HA dried to 23% in FIR dried samples in kaprow khao, whereas methyl eugenol was the main volatile compound in kaprow daeng ranging from 35% in fresh to 49% in FIR dried samples. Our results have demonstrated that LRH and FIR should be considered as a suitable drying method for kaprow with respect to preserving its color, antioxidant property, phenolic compounds, and volatile compounds. The present study has provided useful information for industrial use of kaprow powder production.

Effect of Humidity and UV Assistance on the Properties of Erbium Doped Yttrium Oxide Films Prepared by Aerosol‐MOCVD

AbstractErbium‐doped yttrium oxide films are prepared from yttrium acetylacetonate (Y(C5H7O2)3) and erbium (III) tris(2,2,6,6‐tetramethyl‐3,5‐heptanedionate) (Er(TMHD)3) under standard conditions by UV‐aerosol‐assisted metal‐organic (AA‐MOCVD), using air with controlled humidity as the carrier gas. The structure and deposition rate are optimized by studying three experimental parameters; substrate temperature, relative humidity (RH) of the carrier gas, and UV‐assistance. Taking all these parameter effects under consideration, the maximum deposition rates are reached under low humidity air and with UV‐assistance. Nevertheless, as‐deposited Er:Y2O3 films crystallize in the Y2O3 cubic structure and present a very low organic contamination when depositions take place under high air humidity and with UV‐assistance. The refractive index of yttrium oxide films under these conditions are relatively high, reaching 1.86 when deposited at 410 °C.

Preliminary studies on the influence of dune-slope exposure on a pine forest ecosystem in the Toruń Basin

Ekspozycja stoków wydm w Kotlinie Toruńskiej a wybrane elementy ekosystemu boru sosnowego - wstępne wyniki badań

SYSTEM AND CLIMATE RELATED PYTHIUM PROBLEMS IN MOBILE CHRYSANTHEMUM GROWING SYSTEMS

One Dutch greenhouse company started to grow chrysanthemums in a mobile system. The system’s basic unit is a sub-irrigated V-shaped gully of 8.0 m long and 5 cm wide, filled with a peat-coir mix. The system is hampered by growth differences along the length profile of the gullies and Pythium related yield reductions of up to 10% during the summer period. A series of experiments aimed to mimic the problems, explain causes and to advice on improvements. A Pythium ultimum pathogen from the grower was cultured in the laboratory and disseminated in the irrigation water tanks. In part of the cultivations the plants were subjected to high temperature and low air humidity treatments aimed at creating stress and Pythium susceptibility. Various plugs fit for transporting rooted chrysanthemum cuttings were tested as well. The results show that Pythium ultimum is initially the result of a too high water content in the first 10 days of the propagation phase. This was a direct consequence of precipitation of pure water by the mist system used to keep the relative humidity high. A related factor was a too low EC of

Simulation of the Direct Radiative Effect of Mineral Dust Aerosol on the Climate at the Last Glacial Maximum

Abstract The climatic responses to the direct radiative effect of dust aerosol at the Last Glacial Maximum (LGM) are examined using a general circulation model with online simulation of dust. The predicted global dust emission at the LGM is 2.3 times as large as the present-day value, which is the combined effect of the expansion of dust sources and the favorable meteorological parameters (MPs; e.g., the strong surface wind and the low air humidity) under the LGM climate. Simulated global dust emission is 1966 Tg yr−1 with present-day dust sources and MPs, 2820 Tg yr−1 with LGM dust sources and current MPs, 2599 Tg yr−1 with present-day dust sources and LGM MPs, and 4579 Tg yr−1 with LGM sources and MPs. The simulated percentage increases of dust concentrations are the largest at high latitudes in both hemispheres, which are consistent with the deposition data from geological records. The LGM dust is estimated to exert global annual-mean shortwave (SW) and longwave (LW) radiative forcing (RF) of −4.69 and +1.70 W m−2 at the surface, respectively, and −0.58 and +0.68 W m−2 at the top of the atmosphere, respectively. On a global- and annual-mean basis, surface air temperature (SAT) is predicted to be reduced by 0.18 K and precipitation is reduced by 0.06 mm day−1, as a result of the net (SW and LW) radiative effect of dust at the LGM. Two sensitivity studies are performed to identify the uncertainties in simulated climatic effect of LGM dust that arise from the assumed LW and/or SW absorption by dust: 1) in the absence of dust LW radiative effect, the LGM global- and annual-mean SAT is predicted to be further reduced by 0.19 K; and 2) when the single scattering albedo of the Saharan dust at 0.55 μm is increased from 0.89 to 0.98 in the LGM climate simulation, the LGM dust-induced annual- and global-mean surface cooling increases from 0.18 to 0.63 K even with both SW and LW radiative effects of dust. In these two sensitivity studies, the LGM dust is predicted to induce an average cooling of 0.42 and 0.72 K in SAT, respectively, over the tropical oceans.

Habitat Studies Identifying Potential Trees for Urban Paved Environments: A Case Study from Qinling Mt., China

Trees in urban paved environments are highly exposed to heat, low air humidity, periods of critical water stress, high soil lime content and soil pH, limited soil volume, pollutants, and de-icing salts. Combined with the challenges of climate change and the threat of disease and pest infestations, this has led to considerable and persistent arguments for using a more varied range of trees, including stress-tolerant species, at urban paved sites. Extensive fieldwork was carried out in the Qinling Mountains, China, in a search for tree species suitable for urban paved sites in northern parts of central Europe and in adjoining milder parts of northern Europe (CNE-region), where tree species are exposed to seasonally dry and harsh conditions. The study identified habitats in the Qinling Mountain range that are similar to those at sites in paved environments, and analyzed the growth and performance of different tree species in these habitats. A total of 25 tree species representing 21 genera were found, of which 14 species were identified as specialist colonizers of warm, dry south-facing slopes where site conditions are similar to those in paved environments of the CNE-region.

Hydrological system analysis and modelling of the Nam Co basin in Tibet

Abstract. The Tibetan Plateau and the adjacent high mountain regions of the Himalayas play an important role in the global climate dynamic through its impact on the Asian monsoon system, which in turn is impacting the water resources of this extremely vulnerable region. To provide further knowledge about the changing impact of rainfall patterns, spatial and temporal variability of snow cover contribution, amount of snow and ice melt runoff, evapotranspiration as well as dynamics of wetlands and permafrost water balance studies are required. This is of particular importance in terms of global climate change because of a severe gap in the knowledge of the short, mid and long term implications on the hydrological system. This study concentrates on the macroscale catchment of the lake Nam Co, located at 4718 m a.s.l. at the foot of the Nyainqentanglha Mountains in central Tibet (30° N, 90° E). The water balance of the Nam Co basin is dominated by semi-arid climate, snow and ice melt runoff and high evaporation rates due to the high radiation input and the low air humidity. The observed temperature rise, glacier retreat, permafrost decay and lake level increase indicate significant system changes and the high sensitivity of the Tibetan Plateau on global warming. The development of a suitable water balance model and its preliminary application was the main objective of this study. The development was done with the Jena Adaptable Modelling System JAMS along with existing scientific process components of the J2000 module library which were partly further developed to reflect the specific conditions of the high elevation Nam Co basin. The preliminary modelling exercise based on gridded data from a downscaled ECHAM5 data set provided reasonable estimates about the important hydrological water balance components of the Nam Co basin. With the modelling results the observed lake level rise could be reproduced and it could be shown that the runoff from the glaciered areas seems to be the most important component to explain the increasing amount of lake water.

Experimental investigations of frost release by hydrophilic surfaces

Frost formation occurs when water vapor in the surrounding air comes into contact with cold surfaces through heat and mass transfer. It is usually an undesirable phenomenon in most refrigeration and cryogenic systems. A few studies have shown that changing the surface energy, such as increasing the surface hydrophilicity or hydrophobicity, has significant effects on frost growth. In this paper, a kind of hydrophilic polymer paint is formulated to counteract frost deposition on cold surfaces. The coated surface can retard frost formation up to three hours under low plate temperatures (− 15.3°C) and high air humidity (72%). To test the antifrosting performance of the hydrophilic paint under more practical conditions, it is applied to a fin-and-tube heat exchanger and a domestic refrigerator at a coating thickness of 30 μm. Comparisons of frost deposition, pressure drops, and outlet temperatures are made between uncoated and coated heat exchangers. Under conditions of high air temperature (2.2°C) and relative high air humidity (90%), the paint prolongs the defrosting interval from 80 to 137 min. Experimental observations also show that the coated hydrophilic fins are free of frost deposition during the entire course of the test and that the coating has no significant additional thermal resistance.

Effects of wetting on the persistence of quiescent conidia of Isaria fumosorosea

Quiescent conidia of Isaria fumosorosea were submitted to various wetting–drying cycles under different regimes of temperature and air humidity. Germination and viability of conidia collected on cultures freshly host-passed (P2) were not affected at 25 °C during five cycles at increasing wet phase duration (2–12 h per daily cycle) under any moisture conditions (13–86% RH). Infectivity levels remained stable, but mortality was slightly postponed. In vitro-cultured inocula (P5) were significantly affected after only one cycle at higher air humidity (75 and 86% RH) and temperature (35 and 40 °C). The persistence of I. fumosorosea conidia suspended in water soluble extracts of leaf surfaces (corn and cabbage) confirmed the better persistence of P2 conidia and the relatively higher detrimental effect of lower air humidity conditions when combined with moderate temperatures. Quiescent conidia deposited in situ on potted plants of cabbage showed a higher persistence on wet foliage and on foliage submitted to wetting–drying cycles, than on dry foliage. These results underline that constraints prevailing in targeted environments and ecological fitness of fungal isolates have to be taken into account for assessing microbial control strategies.

Major mite allergen Der f 1 concentration is reduced in buildings with improved energy performance

Environmental conditions play a crucial role in mite growth, and optimal environmental control is key in the prevention of airway inflammation in chronic allergic rhinoconjunctivitis or asthma. To evaluate the relationship between building energy performance and indoor mite allergen concentration in a cross-sectional study. Major allergen concentration (Der f 1, Der p 1, mite group 2, Fel d 1 and Bla g 2) was determined by quantitative dot blot analysis from mattress and carpet dust samples in five buildings designed for low energy use (LEB) and in six control buildings (CB). Inhabitants had received 4 weeks prior to mite measurement a personal validated questionnaire related to the perceived state of health and comfort of living. Cumulative mite allergen concentration (with Der f 1 as the major contributor) was significantly lower in LEB as compared with CB both in mattresses and in carpets. In contrast, the two categories of buildings did not differ in Bla g 2 and Fel d 1 concentration, in the amount of dust and airborne mould collected. Whereas temperature was higher in LEB, relative humidity was significantly lower than in CB. Perceived overall comfort was better in LEB. Major mite allergen Der f 1 preferentially accumulates in buildings not specifically designed for low energy use, reaching levels at risk for sensitization. We hypothesize that controlled mechanical ventilation present in all audited LEB may favour lower air humidity and hence lower mite growth and allergen concentration, while preserving optimal perceived comfort.

A Peculiar Feature of the Seasonal Migration of the South American Rain Band

Seasonal migration of tropical rainfall is examined in the South American sector and compared with that over Africa, using satellite and reanalysis data. While the African rain band moves continuously back and forth across the equator following the seasonal march of the sun, the South American one displays a peculiar asymmetry between its northward and southward migration. The rain band moves gradually northward from October to July from the Amazon toward the Caribbean Sea, while its return to the Amazon is an abrupt event, with convection developing rapidly in October around 10 � S without going through the equator. Over the equatorial Amazon during July–October, equivalent potential temperature (ye) is kept low by the easterly advection of low temperature and humidity air from the equatorial Atlantic, coinciding with the seasonal development of ocean upwelling and a cold tongue in sea surface temperature. The low ye values prevent convection from developing in the equatorial Amazon while warm SST supports convection on the north coast of South America during August–October. Meanwhile solar radiation continues to heat up the land surface to the south, eventually triggering the onset of deep convection there in October.

확산길이에 따른 수동식 유기용제 시료채취기의 시료채취성능에 관한 연구

Passive samplers have been used for many years for the sampling of organic vapors in work environment atmospheres. Currently, all passive samplers used in domestic occupational monitoring are foreign products. This study was performed to evaluate variable parameters for the development of passive organic samplers, which include the geometry of the device and diffusive length for the sampler design. Four prototype diffusive lengths; A-1(4.5 mm), A-2(7.0 mm), A-3(9.5 mm), A-4(12.0 mm) were tested for adsorption performances to a chemical mixture (benzene, toluene, trichloroethylene, and n-hexane) according to the US-OSHA's evaluation protocol. A dynamic vapor exposure chamber developed and verified by related research was used for this study. The results of study are as follows. The results in terms of sampling rate and recommended sampling time test indicate that the most suitable model was A-3 (9.5 mm diffusive lengths on both sides) for passive sampler design in time weighted average (TWA) assessment. Sampling rates of this A-3 model were 45.8, 41.5, 41.4, and 40.3 ml/min for benzene, toluene, trichloroethylene, and n-hexane, respectively. The A-3 models were tested on reverse diffusion and conditions of low humidity air (35% RH) and low concentrations (0.2 times of TLV). These conditions had no affect on the diffusion capacity of samplers. In conclusion, the most suitable design parameters of passive sampler are: 1) Geometry and structure - 25 mm diameter and 490 cross sectional area of diffusion face with cylindrical form of two-sided opposite diffusion direction; 2) Diffusive length - 9.5 mm in both faces; 3) Amount of adsorbent - 300 mg of coconut shell charcoal; 4) Wind screen - using nylon net filters (11 pore size).

Geochemical and environmental controls on the genesis of soluble efflorescent salts in Coastal Mine Tailings Deposits: A discussion based on reactive transport modeling

Water-soluble efflorescent salts often form on tailings in hyperarid climates. Their high solubility together with the high risk of human exposure to heavy metals such as Cu, Ni, Zn, etc., makes this occurrence a serious environmental problem. Understanding their formation (genesis) is therefore key to designing prevention and remediation strategies. A significant amount of these efflorescences has been described on the coastal area of Chañaral (Chile). There, highly soluble salts such as halite (NaCl) and eriochalcite (CuCl 2·2H 2O) form on 4 km 2 of marine shore tailings. Natural occurrence of eriochalcite is rare: its formation requires extreme environmental and geochemical conditions such as high evaporation rate and low relative air humidity, and continuous Cl and Cu supply from groundwater, etc. Its formation was examined by means of reactive transport modeling. A scenario is proposed involving sea water and subsequently a mixture of sea water/freshwater in the groundwater composition in the formation of these efflorescences. The strong competition from other halides (i.e. halite and silvite (KCl)) for the Cl may inhibit the precipitation of eriochalcite. Therefore, the Cl/Na ratio trend > 1 is a key parameter in its formation. Cation-exchange between Na + and other major ions such as K +, Ca 2+, Mg 2+ and Cu 2+ in the clay fraction of tailings is proposed to account for realistic Cl/Na ratios. With regard to preventing the formation of eriochalcite, a capillary barrier on the tailings surface is proposed as a suitable alternative. Its efficiency as a barrier is also tested by means of reactive transport models.

Experimental investigation of dehumidification process in cooling coil by utilizing air-to-air heat exchanger in humid climate of Iran

Energy recovery systems can be used in HVAC to reduce energy consumption by recovering wasted energy from the exhausted air to pre-cool inlet fresh air. In this paper, experimental study of utilizing cooling coil (CC) and cooling coil combined with heat exchanger (CCHE) has been developed. Considering the different climate zones in Iran, the experimental study has been done for the areas with high humidity content. In each case, the effects of air-to-air heat exchanger (HE) on the sensible and latent cooling load are investigated. The analysis gives the applicability of HE in Iran for various operational conditions to obtain air with lower moisture content. In CCHE systems more latent load quota is allocated in cooling coils and lower air humidity ratio can be obtained. Also in the cities with higher dew point depression (difference between dry-bulb and dew point temperature) more humidity reduction is achieved and the difference between latent load quotas of CCHE system is higher than CC system.

Temperate forest herbs are adapted to high air humidity — evidence from climate chamber and humidity manipulation experiments in the field

How growth and morphology of wild plants are controlled by the water vapor saturation deficit of the air (vapor pressure deficit, VPD) is not sufficiently understood. We tested the hypothesis that VPD acts on temperate woodland herbs independently from soil moisture by exposing two species ( Mercurialis perennis L. and Stachys sylvatica Torr.) to variable VPD levels in climate chambers and in open-top chambers on the forest floor. A decrease in air humidity from 85% to 40% in the climate chamber experiment, which simulates a microclimate change after canopy gap creation, resulted in a 40% decrease in biomass production of both species when grown in hydroponic culture. This result is supported by the more realistic open-top chamber experiment, which showed a productivity decrease by approximately 25% when plants were continuously exposed to an atmosphere with 15% lower air humidity than ambient. Elevated VPD levels reduced biomass production through either a reduced leaf expansion rate or a lower number of formed leaf buds. We conclude that many woodland herbs require sufficiently high air humidity for optimal growth; permanently decreased air humidity, as may occur in a future drier climate, after gap creation, or after clear-cutting of the forest, may threaten the vitality and survival of woodland herbs.

The efficiency of fan-pad cooling system in greenhouse and building up of internal greenhouse temperature map

During summer periods, high temperature values that are being formed in greenhouses can greatly influence the efficiency of production workers and also decrease the productivity of plants grown there. A greenhouse production without the cooling systems can be sustained at the desirable level by imposing summer restrictions in the areas with warm climate, and by starting cooling in the areas with cold climate. A statement can be made regarding both utility and efficiency of fan-pad cooling systems that they tend to go up in the areas with low relative air humidity. The present study has been carried out in order to either prove or disprove this statement. We have attempted to create a map of internal greenhouse temperature distribution via determining the system’s efficiency. As a result of this study, it was determined that since air temperature and relative humidity in the air tend to decrease during summer months by using fan-pad cooling system, temperatures in the greenhouse can be consequently lowered down to 10-12°C. Statistical analysis revealed remarkable differences (p<0.01) between the temperatures at various points in greenhouses observed.

Growth patterns of Pinus sylvestris across Europe: a functional analysis using the HYDRALL model

The variability of Pinus sylvestris growth over two geographic transects across Europe has been explored through a process-based forest growth model (Hydrall: HYDRaulic constraints on ALLocation) which accounts for the effects of environmental conditions not only on short-term gas exchanges, but also on allocation and tree structure. The model has been validated against both eddy-covariance and growth data under contrasting environmental conditions. Forest growth was found to be reduced by low temperatures (-50%) and water stress (-37%) at the opposite extremes of the natural range of the species. Application of a functional model made it possible to partition growth reductions between individual processes. Gross primary production was severely affected by low temperatures and short vegetative periods at the northern extreme of the specific range (-53%), and by low air and soil humidity at the southern limit (-26%). The ratio between net and gross primary production was found to be rather constant across the temperate region, only increasing in the boreal zone in response to low temperatures (+20%). Under dry conditions, on the contrary, a substantial proportion of the reduction in aboveground productivity was attributed to the need to allocate increasing amounts of resources to fine root production and maintenance (+16%). Both short and long-term responses should be considered in the prediction of climate change impact on forests.

Trehalose protects against ocular surface disorders in experimental murine dry eye through suppression of apoptosis

The disaccharide trehalose is a key element involved in anhydrobiosis (the capability of surviving almost complete dehydration) in many organisms. Its presence also confers resistance to desiccation and high osmolarity in bacterial and human cells by protecting proteins and membranes from denaturation. The present study used a novel murine dry eye model induced by controlled low-humidity air velocity to determine whether topically applied trehalose could heal ocular surface epithelial disorders caused by ocular surface desiccation. In addition, the efficacy of 87.6 mM trehalose eyedrops was compared with that of 20% serum, the efficacy of which has been well documented. Mice ocular surface epithelial disorders were induced by exposure of murine eyes to continuous controlled low-humidity air velocity in an intelligently controlled environmental system (ICES) for 21 days, which accelerated the tear evaporation. The mice were then randomized into three groups: the control group received PBS (0.01M) treatment; a second group received 87.6 mM trehalose eyedrops treatment; and the third group received mice serum eyedrops treatment. Each treatment was administered as a 10 μl dose every 6 h for 14 days. The resultant changes in corneal barrier function and histopathologic examination of cornea and conjunctiva were analyzed and the level of apoptosis on the ocular surface was assessed using active caspase-3. After 14 days of treatment, the corneal fluorescein staining area, the ruffling and desquamating cells on the apical corneal epithelium, as well as the apoptotic cells on ocular surface epithelium had significantly reduced in eyes treated with trehalose compared with those treated with serum and PBS. In contrast, after 14 days of treatment, improvements in the thickness of the corneal epithelium, the squamous metaplasia in conjunctival epithelium and the number of goblet cells of the conjunctiva were less marked in eyes treated with trehalose compared with serum. These results demonstrated that trehalose could improve the appearance of ocular surface epithelial disorders due to desiccation through suppression of apoptosis. Trehalose produces some of the same responses as serum upon topical application and can maintain corneal health.

Effect of air humidity on the microstructure and properties of large-area YBa 2Cu 3O 7−x films by TFA-MOD process

Large-area YBa 2Cu 3O 7− x (YBCO) films had been successfully fabricated on LaAlO 3 (LAO) substrate by metalorganic deposition using trifluoroacetates (TFA-MOD) and the effect of air humidity on the structure and properties of YBCO films was systematically investigated. The precursor coating process was performed in the air humidity range of 70–40%. According to the X-ray diffraction (XRD) and scanning electron microscopy (SEM) images, the films prepared at high air humidity showed poor electrical performance due to large pores and impurity phases. In contrast, dense, homogeneous and epitaxially grown YBCO films prepared at low air humidity with the critical current densities of 3.8–5.0 MA cm −2 at 77 K had been obtained.