Solvent- and Catalyst-free Synthesis, Hybridization and Characterization of Biobased Nonisocyanate Polyurethane (NIPU)

Nonisocyanate polyurethane (NIPU) is a research hotspot in polyurethane applications because it does not use phosgene. Herein, a novel method of solvent- and catalyst-free synthesis of a hybrid nonisocyanate polyurethane (HNIPU) is proposed. First, four diamines were used to react with ethylene carbonate to obtain four bis(hydroxyethyloxycarbonylamino)alkane (BHA). Then, BHA reacted with dimer acid under condensation in the melt to prepare four nonisocynate polyurethane prepolymers. Further, the HNIPUs were obtained by crosslinking prepolymers and resin epoxy and cured with the program temperature rise. In addition, four amines and two resin epoxies were employed to study the effects and regularity of HNIPUs. According to the results from thermal and dynamic mechanical analyses, those HNIPUs showed a high degree of thermal stability, and the highest 5% weight loss reached about 350 °C. More importantly, the utilization of these green raw materials accords with the concept of sustainable development. Further, the synthetic method and HNIPUs don’t need isocyanates, catalysts, or solvents.

Large Temperature Fluctuations due to Cold-Air Pool Displacement along the Lee Slope of a Desert Mountain

Large temperature fluctuations (LTFs), defined as a drop of the near-surface temperature of at least 3°C in less than 30 min followed by a recovery of at least half of the initial drop, were frequently observed during the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program. Temperature time series at over 100 surface stations were examined in an automated fashion to identify and characterize LTFs. LTFs occur almost exclusively at night and at locations elevated 50–100 m above the basin floors, such as the east slope of the isolated Granite Mountain (GM). Temperature drops associated with LTFs were as large as 13°C and were typically greatest at heights of 4–10 m AGL. Observations and numerical simulations suggest that LTFs are the result of complex flow interactions of stably stratified flow with a mountain barrier and a leeside cold-air pool (CAP). An orographic wake forms over GM when stably stratified southwesterly nocturnal flow impinges on GM and is blocked at low levels. Warm crest-level air descends in the lee of the barrier, and the generation of baroclinic vorticity leads to periodic development of a vertically oriented vortex. Changes in the strength or location of the wake and vortex cause a displacement of the horizontal temperature gradient along the slope associated with the CAP edge, resulting in LTFs. This mechanism explains the low frequency of LTFs on the west slope of GM as well as the preference for LTFs to occur at higher elevations later at night, as the CAP depth increases.

Intelligent Controller Design for Air Conditioning with Multiple Power Saving

An intelligent controller for air conditioning with multiple power-saving is described in this paper. Multiple power-saving feature means: (1) Optimizing the air conditioning compressor curve according to the variation rule of the temperature difference between indoor and outdoor in one day,. (2) Using temperature detection module to control the indoor target temperature no less than pre-set limit and prevent the compressor from starting when outdoor temperature is below the lower limit, (3) Keeping outdoor fan running for a while to make full use of the remaining cooling air stored in the air conditioning when the compressor stops, (4) Cutting the power off when the compressor is standby by using standby monitoring module. The controller hardware is based on ARM microprocessor; connecting with remote control decoding, real-time clock, temperature detection, standby monitoring, and compressor control module. Softwares are made up of main program, remote control decoding program, temperature detection program and compressor control program. After testing, the controller can save more than 20% power and still has a good cooling effect.

Benchmark Solution for the Prediction of Temperature Distributions During Radiofrequency Ablation of Cardiac Tissue

Several studies on radiofrequency (RF) ablation are aimed at accurately predicting tissue temperature distributions by numerical solution of the bioheat equation. This paper describes the development of a solution that can serve as a benchmark for subsequent numerical solutions. The solution was obtained using integral transforms and evaluated using a C program. Temperature profiles were generated at various times and for different convection coefficients. In addition, a numerical model was developed using the same assumptions made in obtaining the benchmark solution. Comparison of surface and axial temperature profiles shows that the two solutions match very closely, cross validating the numerical methods used in evaluating both solutions.

The effects of an Arctic winter on benthic invertebrates in the littoral zone of Char Lake, Northwest Territories

A method was devised for sampling the frozen benthos in the littoral zone of Char Lake, Northwest Territories, a polar lake that was studied during the International Biological Program. Temperature probes indicated that during the winter benthic invertebrates in sediments at 0.5 and 1.75 m were exposed to temperatures as low as −18 and −8 °C, respectively. Mortality in animals that had overwintered in the frozen samples ranged from 13 to 84% (mean 46%) and was attributed mostly to sample processing. With the possible exception of chironomids, no conclusive evidence was found that benthic invertebrates avoid freezing by emigrating to deeper portions of the lake. Exposure to subzero temperatures for 8 months or more increased the synchrony in development of the population of the harpacticoid Attheyella nordenskioldii and shifted its peak reproductive period by about 4 months. These changes implied increases in the population's gross production, growth efficiency, and ecological efficiency. The exposure of shallow-dwelling benthic invertebrates to subzero temperatures is a widespread phenomenon, the effects of which on life cycles and population energetics are poorly known.

Design and Testing of a Plastic Bubble-Film Covered Shallow Solar Pond

A shallow solar pond was designed from inexpensive plastic materials and tested during the summer months. The bag containing the water consisted of a black polyethylene bottom (1.5 mil) covered with a clear polyvinylchloride top (4 mil) and a layer of polyethylene bubble-film on the top of the PVC bag. The bubble-film material is of the type commonly used for protection of breakable goods during shipment. The bubble-film material provided an inexpensive and effective upper glazing for the bag assembly. The bag was insulated from bottom losses by placing it on a 2.22-cm (0.875-in.)-thick layer of polystyrene foam. Tests were performed during May, June, and July 1980. These tests were performed by batch-filling the bag in the morning with a measured quantity of water and measuring the temperature rise of the water during the day. Measurement of water quantity, initial temperature, final temperature, and total incident radiation allowed for calculation of a daily efficiency for the pond. Tests were made for water depths of 5.2 and 10.2 cm (2.05 and 4 in.). Maximum daily efficiencies of up to 63 percent were recorded during the testing. Daily efficiency was determined by dividing the total daily heat collection of the pond by the total radiation incident on the pond for the day. Maximum water temperature of 67°C (152°F) was reached during the testing program. Temperature rise in the pond assembly was typically on the order of 33–39°C (60–70°F) during clear days.