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1.
Dehydration reduces the main phase transition pressure of phospholipids. An analysis based on the Gibbs-Duhem equation shows how the shift of the transition pressure is correlated to the hydration pressure.By using Fourier transform infrared (FT-IR) spectroscopy we determined the hydration-dependent phase transition pressure. The application of our new approach gives hydration pressure values which agree with the values obtained with the osmotic stress method. 相似文献
2.
To study the reliabiliity of formulas for calculating mean skin temperature (T
sk), values were computed by 18 different techniques and were compared with the mean of 10,841 skin temperatures measured by
infrared thermography. One hundred whole-body infrared thermograms were scanned in ten resting males while changing the air
temperature from 40° C to 4° C. Local, regional average and mean skin temperatures were obtained using an image processing
system. The agreement frequency, defined as the percentage of the calculated T
sk values which agreed with the corresponding infrared thermographic T
sk within ±0.2° C, ranged for with the various formulas from 7% to 80%. In many sites, the local skin temperature did not coincide
with the regional average skin temperature. When the local skin temperatures which showed the highest percentage similarity
to the regional average skin temperature within ±0.4° C were applied to the formula, the agreement frequency was markedly
improved for all formulas. However, the agreement frequency was not affected by changing the weighting factors from specific
constants to individually measured values of regional surface area. By applying the physiologically reliable accuracy range
of ±0.2° C in the moderate and ±0.4° C in the cool condition, agreement frequencies of at least 95% were observed in formulas
involving seven or more skin temperature measurement sites, including the hand and foot. We conclude that calculation of a
reliable mean skin temperature must involve more than seven skin temperature measurement sites regardless of ambient temperature.
Optimal sites for skin temperature measurement are proposed for various formulas.
Received: 2 December 1996 / Accepted: 25 June 1997 相似文献
3.
Summary Conformational preferences of secretin as a model peptide have been analyzed by CD and IR spectroscopy in reverse micelles of AOT/isooctane/water and compared to those in aqueous TFE, in SDS micelles and in DMPG vesicles. Among the systems examined, reverse micelles and phospholipid vesicles displayed almost identical conformational equilibria. Very high lipid-to-peptide ratios can be obtained in reverse micelles with full retention of optical transparency, even at millimolar peptide concentrations, thus indicating this system to be an interesting mimic of cell membrane environments for spectroscopic analysis of bioactive peptide conformations.Abbreviations TFE
trifluoroethanol
- SDS
sodium dodecyl sulfate
- DMPG
dimyristoylphosphatidylglycerol
- AOT
bis(2-ethylhexyl)sulfosuccinate
- CMC
critical micellar concentration
- VIP
vasoactive intestinal peptide 相似文献
4.
Visible and infrared spectra of bacteriorhodopsin films under different humidities at room and low temperatures are investigated. On dehydration of purple membranes at room temperatures an additional chromophore state with the absorption band at 506 nm is revealed. The photocycle of purple membranes in the dry state is devoid of the 550 nm intermediate and involves the long-lived intermediate at 412 nm. As water is removed, the 550 nm intermediate becomes undetectable. The analysis of the infrared spectra shows that dehydration does not affect the ordering of the main network of the interpeptide hydrogen bonds which stabilizes the -helical conformation (slightly distorted in the initial humid dark- and light-adapted state); light adaptation (cis-trans isomerization) of bacteriorhodopsin results in an increase of sorbed water in purple membranes. Dehydration of purple membranes decreases the reaction rate of cis-trans isomerization. 相似文献
5.
Tokuo Ogawa Junichi Sugenoya Norikazu Ohnishi Keiko Natsume Megumi Ochiai Motohiko Nishida Norihiko Shinoda Kenichi Katoh Ritsuko Imamura 《International journal of biometeorology》1991,35(1):18-23
In an attempt to detect differences in the thermal effect of infrared irradiation of different wavelengths, transient sweating response to infrared irradiation in various spectral regions was examined. In Series 1, the ventral or dorsal surface of the nude subject was irradiated repetitively for a period of 4 min (2 min on, 2 min off) by each of three kinds of infrared heaters with main emissivity in near-infrared (NIR; 0.7–2.8 m), intermediate-infrared (MIR; 1.5–5.8 m), and far-infrared (FIR; 2.8–25 m) regions. The sweating response on a non-irradiated area tended to be the greatest with MIR, while the magnitude of the sweating response on the irradiated area showed no consistent differences among various wavelengths. The results infer that MIR stimulated cutaneous thomoreceptors most effectively, while its direct effect on local sweat gland activity was minimal. In Series 2, the effects of 9–12 min irradiations in more restricted ranges of wavelength were compared by the combination of the three kinds of heaters with filters (translucent to wavelength ranges of 1.3–2.7, 2.7–3.5, 3.6–8.0 m, respectively). The sweating response on a remote area was predominantly greater with the range of 2.7–3.5 m than with the other wavelength ranges, while the local effect on sweating was minimal with this range. The results of Series 2 reinforce those of Series 1, indicating that the degree of stimulation of cutaneous thermoreceptors and of direct thermal effect on sweat gland activity differ with spectral regions incident on the skin, thus affecting local and remote effects on the sweating response. 相似文献
6.
C. M. Girard 《Plant Ecology》1982,48(3):219-226
Two radiometers measuring reflectance factors have been used at a height of 1.50 m above some grasslands in C. France. The results show that both spectral data are sensitive to the photosynthetic activity of the grassland. Measurements made in April, May, June and July show that grasslands have quite different spectral behaviour according to soil conditions or to grazing level. Grasslands on dry or wet soils may be separated from those of normal soils for which overgrazing and trampling affecting the growth of species, are shown by the different spectral values. Such on the ground remote sensing measurements may then be proposed for evaluating the range of growth and development of different grasslands.Convention C.N.E.S./I.N.A.P-G. ref.: 80/CNES/24 I thank CNES and IGN for the facilities given to assume this experiment. Many thanks to Lynn Erselius, who revised the text. Mr. Lecordix, a student from the Ecole Nationale des Sciences Géographiques and Mr. Besnard, a student from the Orsay University (Plant Biology) helped in the collection and handling of spectral resp, floristical data. 相似文献
7.
The maximum leaf surface temperatures (MLSTs) of 126 species of higher plants were measured by means of an infrared thermometer,
in the Inland Sea area, southwest of Honshu-Island, Japan, where plants suffered from severe environmental conditions due
to an abnormally small amount of precipitation during the summer of 1978. The MLSTs of plants in the summer of 1978 were greater
than or equal to those of 1979, when the environmental conditions were not so severe.
The MLST measured in this study was 50.4 C for a non-succulent plant (Liriodendron), and 53.1 C for a succulent plant (Agave). Plants with different life forms appeared to have different MLSTs. The average of the MLSTs of conifers deciduous trees,
and evergreens were 36.4, 37.7, and 40.3 C, respectively. This order corresponds to the distribution of forests from high
to low, latitudes. Also the MLSTs were higher for woody plants than for herbaceous plants. Relatively high leaf temperatures
were observed for climbing plants, both herbaceous and woody.
Plants with narrow leaves had lower leaf surface temperatures than those with borad leaves. Herbaceous dicotyledonous plants
actively growing at the end of the summer of 1978, in full sun at Hiroshima Castle were exclusively those with relatively
high leaf temperatures. 相似文献
8.
Occurrence frequencies and regional variations in Visible Infrared Imaging Radiometer Suite (VIIRS) global active fires 总被引:2,自引:0,他引:2
Peng Li Chiwei Xiao Zhiming Feng Wenjun Li Xianzhou Zhang 《Global Change Biology》2020,26(5):2970-2987
Active fires are considered to be the key contributor to, and critical consequence of, climate change. Quantifying the occurrence frequency and regional variations in global active fires is significant for assessing carbon cycling, atmospheric chemistry, and postfire ecological effects. Multiscale variations in fire occurrence frequencies have still never been fully investigated despite free access to global active fire products. We analyzed the occurrence frequencies of Visible Infrared Imaging Radiometer Suite (VIIRS) active fires at national, pan‐regional (tropics and extratropics) to global scales and at hourly, monthly, and annual scales during 2012–2017. The results revealed that the accumulated occurrence frequencies of VIIRS global active fires were up to 12,193 × 104, yet exhibiting slight fluctuations annually and with respect to the 2014–2016 El Niño event, especially during 2015. About 35.52% of VIIRS active fires occurred from July to September, particularly in August (13.06%), and typically between 10:00 and 13:00 Greenwich Mean Time (GMT; 42.96%) and especially at 11:00 GMT (17.65%). The total counts conform to a bimodal pattern with peaks in 5°–11°N (18.01%) and 5°–18°S (32.46%), respectively, alongside a unimodal distribution in terms of longitudes between 15°E and 30°E (32.34%). Tropical annual average of active fire (1,496.81 × 104) accounted for 75.83%. Nearly 30% were counted in Brazil, the Democratic Republic of the Congo, Indonesia, and Mainland Southeast Asia (MSEA). Fires typically occurred between June (or August) and October (or November) with far below‐average rainfall in these countries, while those in MSEA primarily occurred between February and April during the dry season. They were primarily observed between 00:00 and 02:00 GMT, between 12:00 and 14:00 within each Zone Time. We believed that VIIRS global active fires products are useful for developing fire detection algorithms, discriminating occurrence types and ignition causes via correlation analyses with physical geographic elements, and assessment of their potential impacts. 相似文献
9.
Anna U. Eriksson Christoffer Svensson Andreas H?rnblad Abbas Cheddad Elena Kostromina Maria Eriksson Nils Norlin Antonello Pileggi James Sharpe Fredrik Georgsson Tomas Alanentalo Ulf Ahlgren 《Journal of visualized experiments : JoVE》2013,(71)
By adapting OPT to include the capability of imaging in the near infrared (NIR) spectrum, we here illustrate the possibility to image larger bodies of pancreatic tissue, such as the rat pancreas, and to increase the number of channels (cell types) that may be studied in a single specimen. We further describe the implementation of a number of computational tools that provide: 1/ accurate positioning of a specimen''s (in our case the pancreas) centre of mass (COM) at the axis of rotation (AR)2; 2/ improved algorithms for post-alignment tuning which prevents geometric distortions during the tomographic reconstruction2 and 3/ a protocol for intensity equalization to increase signal to noise ratios in OPT-based BCM determinations3. In addition, we describe a sample holder that minimizes the risk for unintentional movements of the specimen during image acquisition. Together, these protocols enable assessments of BCM distribution and other features, to be performed throughout the volume of intact pancreata or other organs (e.g. in studies of islet transplantation), with a resolution down to the level of individual islets of Langerhans. 相似文献
10.
Individual feed consumption and animal weight were continuously recorded in grower pigs using an automated feeding system. Infrared images were recorded each time a pig entered the feeding system and infrared thermography provided radiated thermal measurements of the dorsal surface of each animal. Feed was withdrawn and the animals fasted for a period of 24 h three times during the growth of the animals at body weights of approximately 35, 65 and 105 kg. There was a significant reduction of 0.28 °C in the maximum surface temperature (Tmax), and 0.48 °C in the average surface temperature (Tmean) during the periods of fasting. Maximum and average pig temperatures exhibited negative correlations to feed consumption and growth variables. There were negative correlations of residual feed intake (RFI) to Tmax and Tmean radiated temperatures. There were positive correlations of residual gain (RG) and residual intake and gain (RIG) with Tmax and Tmean. The Tmax and Tmean temperature responses to fasting were negatively associated with feed consumption and growth variables. Absolute temperature and temperature response variables were positively associated with RFI and negatively associated with residual intake and gain (RIG). These findings provide support for the concept of radiated heat losses as a measure of metabolic activity and a predictor of growth performance. 相似文献