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At least 739 records · Page 41Linked to original sources
PubMed2003

Superior performance of African runners in warm humid but not in cool environmental conditions.

The purpose of this study was to examine the running performances and associated thermoregulatory responses of African and Caucasian runners in cool and warm conditions. On two separate occasions, 12 (n = 6 African, n = 6 Caucasian) well-trained men ran on a motorized treadmill at 70% of peak treadmill running velocity for 30 min followed by an 8-km self-paced performance run (PR) in cool (15 degrees C) or warm (35 degrees C) humid (60% relative humidity) conditions. Time to complete the PR in the cool condition was not different between groups ( approximately 27 min) but was significantly longer in warm conditions for Caucasian (33.0 +/- 1.6 min) vs. African (29.7 +/- 2.3 min, P < 0.01) runners. Rectal temperatures were not different between groups but were higher during warm compared with cool conditions. During the 8-km PR, sweat rates for Africans (25.3 +/- 2.3 ml/min) were lower compared with Caucasians (32.2 +/- 4.1 ml/min; P < 0.01). Relative rates of heat production were less for Africans than Caucasians in the heat. The finding that African runners ran faster only in the heat despite similar thermoregulatory responses as Caucasian runners suggests that the larger Caucasians reduce their running speed to ensure an optimal rate of heat storage without developing dangerous hyperthermia. According to this model, the superior running performance in the heat of these African runners can be partly attributed to their smaller size and hence their capacity to run faster in the heat while storing heat at the same rate as heavier Caucasian runners.

Africa, Eastern↗
PubMed2003

Fourier transform Raman spectrometry for the quantitative analysis of oil content and humidity in olives.

A method for the direct and fast determination of oil content and humidity in olives using Fourier transform Raman spectrometry is reported. The only sample preparation step required was crushing of the olives using a hammer mill. The crushed olives were placed in a dedicated sample cup, which was rotated excentrically to the horizontal laser beam during spectrum acquisition. This allowed us to sample an increased volume and thus compensate for sample inhomogeneities. In this way the reproducibility of Raman spectra taken from crushed olives was significantly improved. Partial least-squares (PLS) regression was used for the chemometric evaluation of the Raman spectra. Standard errors of prediction for the validation set of 0.81% for oil content (in the range 19.68-35.71%) and 1.54% for humidity (in the range 29.23-51.49%), both expressed as weight percentage referred to fresh matter, were obtained.

Food Analysis↗
PubMed1992

Forage availability x heifer phenotype interactions for Brahman-Hereford F1 yearling heifers grazing humid pasture and semiarid rangeland.

Yearling heifer growth data were obtained during 4 yr for 524 heifers allotted to either humid bermuda grass pastures (Overton) or semiarid rangeland (Uvalde). Each year, heifers were allotted on April 15 to four forage availability levels (400 to 2,800 kg of DM per 100 kg of BW at Uvalde and 80 to 260 kg of DM per 100 kg of BW at Overton) maintained by varying the stocking rate monthly until mid-October of each year. Forage availability and yearling heifer characteristics (weight, condition score, and height at hooks, taken on April 15) were treated as continuous variables in regression analyses. Final heifer weight, height, and condition responses to increased forage allowance were related to yearling phenotypes differently for the two locations. Generally, at Overton, forage availability influenced final characteristics to a greater extent than did yearling variables, whereas the trend was the opposite at Uvalde. At Uvalde, the yearling characteristic that had the largest effect on performance was height at hooks. Yearlings with large frames benefited from increased forage allowance by accumulating body fat at a faster rate than those with small frames. In contrast, at Overton, the yearling characteristic that had the largest effect on performance was condition. Fat heifers responded to increased forage availability to gain even greater advantages in fatness at the expense of potential growth in height and, thus, achieved early maturation. Yearling phenotypes were more broadly adapted to arrays of forage availability for humid, improved pastures than for semiarid rangeland.

Adipose Tissue↗
PubMed1996

Transmission of genital human papillomavirus infections is unlikely through the floor and seats of humid dwellings in countries of high-level hygiene.

To evaluate the transmission of genital human papillomavirus (HPV) through the floor and seats of humid dwellings, samples were collected with a toothbrush from the floor and seat surfaces of humid dwellings; showers, saunas and dressing rooms. The survey included 3 bathing resorts, 1 indoor swimming pool, 2 schools and 2 private homes. Polymerase chain reaction (PCR) was used to amplify the human beta-globin gene and HPV DNA. The results for HPV DNA amplification were confirmed by Southern blot hybridization under low stringency using a probe mixture of HPV types 6, 16, 18 and 31. beta-globin could be amplified only from 3 sample taken from a dressing room of and indoor public swimming pool. No HPV DNA-positive samples were found. These results indicate that transmission of genital HPV infection via floor or seat surfaces in the above dwellings in general or family use is highly unlikely.

Adolescent↗
PubMed2001

Pteridium aquilinum (bracken fern) toxicity in cattle in the humid Chaco of Tarija, Bolivia.

We studied the toxicity caused by chronic ingestion of Pteridium aquilinum (bracken) in cattle in the humid Chaco of Tarija, Bolivia. Bovine enzootic haematuria (BEH) and Carcinoma of the esophagus (CE) affected the herds. Sick animals showed caquexia, anemia, leucopenia and urine that turned from pink to intense red color with the presence of blood clots. Cattle grazed in the humid forests of the mountains where P aquilinum represented more than 50% of the plants. P aquilinum var arachnoideum and P aquilinum var Caudatum were present. Toxic norsesquiterpene, ptaquiloside, was identified in both varieties. Carcinomas were in the urinary bladders and esophagus of 100% and 50% of the cattle, respectively. Control of the intoxication could be difficult due to geographic characteristics of this Bolivian region.

Animals↗
PubMed1994

Effect of temperature and humidity on hardness and friability of packaged paracetamol tablet formulations.

The influence of various temperature and relative humidity conditions on changes in hardness and friability of five commercial brands of packaged paracetamol tablets stored over a period of six months has been investigated. At 75% RH all sample show deterioration in hardness at 25 degrees (5-10%) and at 45 degrees (10-39%). At 100% RH there is a little difference in deterioration in hardness at 25 degrees (16-24%) and 45 masculine (20-28%) suggesting that once the critical moisture content is reached by the tablets, further increase in relative humidity has little effect on changes in hardness. Under the same conditions, all tablets show an increase in friability ranging from 2.83 to 8.02%. The overall increase in friability with an increase in temperature from 25 degrees to 45 degrees at 75% and 100% RH is 0.0 to 25.2%. The results indicate that moisture sorption by tablet matrix through certain packaging materials may adversely affect the hardness and friability characteristics.

Journal Article↗
PubMedDate not supplied

[Acidic components of precipitation: humid deposition of S, N and Cl compounds].

Precipitation samples have been gathered using recipients that differentiate the dry deposition of the humidity in three stations in Spain: one urban (Madrid) and two at base levels (San Pablo de los Montes and Granada). The study is centred on the components of an acid character, for which significant special variations of the sulphate and nitrate concentrations have been obtained. The levels, highest in Madrid and lowest in San Pablo, show the influence of the emitting focal points. A study of the seasonal variations in San Pablo show that the concentrations in summer are more than double than those in winter, probably due to the intervention of the photochemical formation processes of these contaminants. Also studies of humidity deposition are carried out, from which one can observe greater monthly values that are greater in Madrid than in other stations, in spite of having less rainfall. Likewise, episodes of "acid rain" and "red rain" are commented on.

Acid Rain↗
PubMedDate not supplied

[Malarial indices in 938 children and adolescents in the humid savanna area of the south of Mali].

The authors draw up "paludometric indications" by studying 938 children and youths, in the Kadiolo area, a humid savanna in the south of Mali, by the end of the dry season (beginning of March). These results give a global indication of 70.6% (cases of malaria) with 94.4% of P. falciparum and 9.96% cases of gametocytic indications. The numbers obtained far from the rainy season let us think that the annual transmission of malaria is continuous with a recrudescence in the humid season explaining largely the infantile mortality. The use of Nivaquine may easily protect these populations from the risk of malaria disease.

Adolescent↗
PubMedDate not supplied

[Are nitrogen bases of DNA hydrated at low humidity?].

The infrared spectra (1450-1800 cm-1) of DNA films derived at different relative humidity are presented. An analysis of the observed frequency and intensity changes of infrared bonds assigning to the intra- and interring vibrations indicates that the nitrogen bases of DNA become hydrated at low (0-64%) relative humidities.

Chemical Phenomena↗
PubMed1962

Effect of relative humidity on the bactericidal activity of propylene oxide vapor.

Because of the low toxicity of its breakdown product, propylene oxide (PO) vapor will play an increasingly important role in the preservation of foods. It is therefore necessary that the diversified variables which influence effectiveness of PO treatment be thoroughly investigated and understood prior to advocating its general use in industry. Accordingly, the present study was undertaken to determine the effect of relative humidity (RH) upon the bactericidal activity of PO sterilant atmospheres. Death rates were established at increasing RH values of < 1, 52, 65, 80, and 98% and under constant conditions of concentration, pressure, and temperature. Test bacterial populations were preconditioned to corresponding moisture levels. Results indicate that gram-positive cocci were relatively insensitive to PO vapor at dry conditions but became progressively less resistant with the increase in RH up to a maximum of 65 to 70%. Lactic acid bacteria and gram-negative rods were much more sensitive at dry conditions, showing much less dependency upon water vapor. Bacillus subtilis spores elicited the highest degree of resistance but the death rate substantially increased with the increase in RH.

Bacillus subtilis↗
PubMed1996

Comparison of detection methods for trichothecenes produced by Fusarium sporotrichioides on fodder and grains at different air humidities.

Growth and toxin production of a highly toxic strain of Fusarium sporotrichioides Sherb were studied on oat and wheat grains and on straw under experimental conditions, in which relative humidity (RH) of air was regulated. The materials were incubated at three different RH levels at a range of 84-100%. F. sporotrichioides grew well on oat and wheat grains at RH 97-100% but grew less well at RH 84-88% and on straw. Toxin production was measured with three biological toxicity tests (cytotoxicity test, dermotoxicity test, and yeast cell toxicity test), with chemical analysis, and T-2 ELISA assay. Cytotoxicity and production of trichothecene mycotoxins were detected in all the samples incubated at all three RH levels. On oat and wheat grains, T-2 toxin, neosolaniol, and diacetoxyscirpenol were found, and on straw T-2 toxin, HT-2 toxin, neosolaniol, and T-2 tetraol were determined. In the T-2 ELISA assay, all material samples were found to contain T-2 toxin. The cytotoxicity test was the most sensitive method for detecting biological toxicity of samples inoculated with fungus. The T-2 ELISA assay and chemical analysis were about equally sensitive to detect T-2 toxin in samples.

Animal Feed↗
PubMed2007

Fungal biofiltration of alpha-pinene: effects of temperature, relative humidity, and transient loads.

Over the past decade much effort has been made to develop new carrier materials, more performant biocatalysts, and new types of bioreactors for waste gas treatment. In biofilters fungal biocatalysts are more resistant to acid and dry conditions and take up hydrophobic compounds from the gas phase more easily than wet bacterial biofilms. In the present study, a biofilter packed with a mixture of perlite and Pall rings and fed alpha-pinene-polluted air was inoculated with a new fungal isolate identified as Ophiostoma species. alpha-Pinene is a volatile pollutant typically found in waste gases from wood-related industries. The temperature of waste gas streams from pulp and paper industries containing alpha-pinene is usually higher than ambient temperature. Studies were undertaken here on the effect on performance of temperature changes in the range of 15-40 degrees C. The effect of temperature on biodegradation kinetics in continuous reactors was elucidated through equations derived from the Arrhenius formula. Moreover, the effects of the relative humidity (RH) of the inlet gas phase, transient loads (shock or starvation), and the nature of the nitrogen source on alpha-pinene removal were also studied in this research. The results suggest that the fungal biofilter appears to be an effective treatment process for the removal of alpha-pinene. The optimal conditions are: temperature around 30 degrees C, RH of the inlet waste gas stream around 85%, and nitrate as nitrogen source. The fungal biofilter also showed a good potential to withstand shock loads and recovered rapidly its full performance after a 3-7 days starvation period.

Air Pollutants↗
PubMed1993

Effect of time, temperature and humidity on biodeterioration of corn cake snack.

Food spoilage microorganisms representing 5, 6 and 10 genera of moulds, yeasts and bacteria, respectively were isolated from corn cake snack. Each of the samples analysed had initial pH value favourable to microbial growth and activities while only 28% had spoilage-enhancing moisture contents (> 13%). The effect of temperature and relative humidity (RH) on biodeterioration during a 24-day storage period was determined by monitoring changes in the pH and total microbial colony counts. Whereas very little or no deterioration was recorded for samples contained in 51% and 71% RH chambers at 30 and 45 degrees C, substantial deterioration was obtained at the same temperatures under 89.5% and 100% RH. At 15 degrees C, very little or no deterioration was detected except under 79.5%, 89.5% and 100% RH when slight spoilage changes were recorded as from the 12th or 18th day. The overall results show that the obtained colony counts and pH values monitor spoilage equally.

Bacteria↗
PubMed1994

Effects of sodium chloride and relative humidity on growth and sporulation of moulds isolated from cured fish.

A total of 14 moulds were isolated from 84 samples of cured fish obtained from several processing centres and retail shops in Lagos, Ogun and Oyo States, Nigeria. Aspergillus niger, A. flavus and A. chevalieri were the most prevalent. With the exception of Basipetospora sp., slight inhibition of mycelial growth and/or sporulation was recorded when isolates were cultured in basal medium containing 5% sodium chloride. The extent of inhibition increased with increasing salt concentrations, and at 25% level all the species had their growth completely inhibited. When fish substrates inoculated with test fungi were kept inside 65% relative humidity (RH) chambers for 21 days, no detectable utilization of the substrates was recorded for any of the fungal species. Whereas only A. chevalieri and A. restrictus utilized the substrates when placed inside 70% RH chambers, all the test moulds recorded detectable utilization (though at varying extents) of same at 80% and 90% RH levels. The latter RH was the most conductive and under it A. niger, Penicillium sp. and the two isolated Scopulariopsis sp. brought about the greatest loss in weight of the substrates.

Animals↗
PubMed1988

Spread of acute hemorrhagic conjunctivitis due to enterovirus-70: effect of air temperature and relative humidity on virus survival on fomites.

Enterovirus 70 (EV-70) has caused at least two pandemics and several major epidemics of acute hemorrhagic conjunctivitis (AHC) in the past 18 years, with the largest number of cases occurring in the coastal areas of the tropics. The exact means of its spread are not known, but fomites and hands contaminated by them are the most likely vehicles. We, therefore, tested EV-70 survival under different environmental conditions using stainless steel disks (1 cm diameter). Each disk received 10 microliter of the virus in phosphate-buffered saline (PBS). The disks were held at various temperatures with the relative humidity (RH) at the low (20 +/- 5%), medium (50 +/- 5%), high (80 +/- 5%), or ultrahigh (95 +/- 5%) level. The virus was eluted from the disks with tryptose phosphate broth and the eluate assayed in LLC-MK2cells. Inactivation rates (Ki), expressed as hourly loss of virus plaque forming units (PFU) in log10, were then calculated. At 20 degrees C, virus survival was proportional to the RH level, with the highest virus survival at the ultrahigh RH; at this level nearly 5% of the input virus was detectable even after 24 hr. Virus inactivation rates were only slightly higher at the ultrahigh RH when the temperature was raised to 33 degrees C or 35 degrees C. However, at 80% RH, increasing the temperature from 20 degrees C to 33 degrees C resulted in a dramatic rise in virus inactivation. The finding that high levels of RH prolong EV-70 survival on fomites may help explain the epidemiology of AHC resulting from EV-70.

Animals↗
PubMed2007

Investigation of drying stresses on proteins during lyophilization: differentiation between primary and secondary-drying stresses on lactate dehydrogenase using a humidity controlled mini freeze-dryer.

This article describes the design, performance testing, and application of a controlled humidity mini-freeze-dryer in studying the physical stability of lactate dehydrogenase during lyophilization. Performance evaluation of the mini-freeze-dryer was conducted with tests, namely water sublimation, radiation heat exchange, lowest achievable temperature, and leak testing. Protein stability studies were conducted by comparing protein activity at various stages of lyophilization with the initial activity. The shelf and condenser temperature were stable at <-40 degrees C, wall temperature was within 2 degrees C of the shelf temperature, and the leak rate was small. The chamber pressure was controlled by the ice on the condenser and the product temperature during sublimation was equal to the shelf temperature. Addition of Tween 80 prevented activity loss in solution and after freeze-thaw. No activity loss was observed after primary-drying even in absence of lyoprotectants and with collapse of cake structure. Five percent (w/w) sucrose concentration was required to achieve full stabilization. In conclusion, performance testing established that the mini-freeze-dryer was suitable for mechanistic freeze-drying studies. Secondary-drying was the critical step for protein stability. The concentration of sucrose required to stabilize the protein completely was several orders of magnitude higher than that required to satisfy the direct interaction requirement of the protein.

Animals↗
PubMed1976

Effect of storage at specified temperature and humidity on properties of three directly compressible tablet formulations.

Direct compression tablets containing sodium starch glycolate, an alginate derivative, or povidone as a disintegrant, magnesium stearate as a lubricant, amaranth as a tracer, and dibasic calcium phosphate dihydrate as the matrix were stored for 30 days at 23 degrees and 75% relative humidity (R.H.), 45 degrees and 75% R.H., and 65 degrees and 40% R.H. Samples were evaluated after 0, 10, 20, and 30 days for size, hardness, and dissolution characteristics. Although no significant changes in the dimensions or hardness of the three tablet formulations, prepared at three different compaction pressures, were observed, the dissolution efficiency of the systems showed significant changes, some systems dissolving more rapidly and some more slowly after storage. In some cases, the changes were so substantial as to indicate the possibility of significant changes of the bioavailability of drugs formulated in such systems. The relevance of this work to the problem of evaluating aging effects on the physical properties of tablets is discussed.

Drug Stability↗