scholarly journals Laws Governing Free and Actual Drying Shrinkage of 50 mm Thick Mongolian Scotch Pine Timber

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1500
Author(s):  
Xiaodong Zhu ◽  
Jingyao Zhao ◽  
Wanhui Gao ◽  
Cheng Qian ◽  
Yunjia Duan ◽  
...  
Keyword(s):  
Early Stage ◽  
Drying Shrinkage ◽  
Shrinkage Strain ◽  
Scotch Pine ◽  
Free Shrinkage ◽  
Different Temperatures ◽  
Conventional Drying ◽  
Sawn Timber ◽  
The Difference ◽  
Shrinkage Coefficient

The relationships between free shrinkage and actual shrinkage of different layers in Mongolian Scotch pine (Pinus sylvestris var. mongolica Litv.) were explored to provide basic data for the further study of drying shrinkage properties. The free shrinkage coefficients at different temperatures and the actual shrinkage strain of each layer were examined under conventional drying. The results showed high precision of free drying shrinkage of corresponding layers of thin small test strips in each layer of sawn timber. The free shrinkage increased linearly as moisture content declined. At the same temperature, the free shrinkage coefficient reached the largest values for the first layer (above 0.267), while the smallest values were recorded for the ninth layer (below 0.249). Except for the ninth layer, the free shrinkage coefficients in width directions of other representative layers decreased as temperature increased. At constant temperature, the difference in free shrinkage coefficient of test materials in the length direction of sawn timber was small for the first layer, but slightly larger and changed irregularly in the fifth and ninth layer direction. At the end of conventional drying, the plastic deformation of each layer in the early stage of drying showed a reducing trend or even reversal due to the effects of reverse stress and later damp heat. In sum, these findings look promising for future optimization of wood drying process.

Study on Durability of High Bending Strength Pavement Concrete

2012 ◽  
Vol 594-597 ◽  
pp. 1372-1376
Author(s):  
Wei Hong Guo
Keyword(s):  
Wear Resistance ◽  
Bending Strength ◽  
Drying Shrinkage ◽  
Fatigue Property ◽  
Plain Concrete ◽  
Shrinkage Strain ◽  
Test Results ◽  
Concrete Material ◽  
Shrinkage Coefficient ◽  
Pavement Concrete

In order to explore the durability of high bending strength pavement concrete, adding silica flour, fibrous reticulum, SD emulsion and HG emulsion separately in concrete mixture, the shrinkage characteristic, wear resistance and fatigue property of different high bending strength pavement concrete are tested, and contrastive analysis with the plain concrete material is researched. The test results show that the early contraction of HBSPC is bigger, but the total drying shrinkage strain is smaller than plain concrete, and the drying shrinkage stable stage of HBSPC is shorter than plain concrete. The temperature shrinkage of HBSPC and plain concrete is uniform basically, the temperature shrinkage coefficient of HBSPC is lower than the plain concrete in the negative warm area and warm area, but it is higher in 0 °C neighbor. The mixtures of the material enhance the wear resistance and fatigue property of concrete.

Modeling swelling–shrinkage behavior of compacted expansive soils during wetting–drying cycles

2015 ◽  
Vol 52 (6) ◽  
pp. 783-794 ◽  
Author(s):  
Gang Wang ◽  
Xing Wei
Keyword(s):  
Deformation Behavior ◽  
Early Stage ◽  
Expansive Soils ◽  
Level Structure ◽  
Shrinkage Strain ◽  
Model Parameters ◽  
Microstructural Parameters ◽  
Phenomenological Perspective ◽  
The Difference ◽  
Reversible Component

This paper presents a straightforward approach for modelling volume change behavior of expansive soils during wetting–drying cycles. The swelling–shrinkage strain of expansive soils induced by cyclic wetting and drying was decomposed with distinctive physical background into a reversible component, which shows a synchronous change with the cyclic change of suction, and an irreversible component, which is generated mainly in the early stage of the wetting–drying process. The mechanisms of the two swelling–shrinkage strain components can be well explained through the double-level structure of expansive soils and its evolution with mechanical and hydraulic loading. The reversible component originates from the reversible deformation behavior of aggregates, and primarily depends on current suction or water content. The irreversible component is associated with the irreversible change of macrostructure, reflecting the difference in soil structures at current state and the equilibrium state. A practical constitutive model was proposed for compacted expansive clays from a global and phenomenological perspective. The model parameters can be calibrated with observed macroscopic deformation behavior without measuring microstructural parameters. The performance of the presented model was validated by simulating cyclic suction-controlled tests as well as an alternately soaked and dried test with irregular amplitudes of suctions.

scholarly journals Analysis of Shrinkage Phenomena in the Process of Cheese Vacuum Drying

2021 ◽  
Author(s):  
Vladimir Ermolaev ◽  
Ivan Kechkin ◽  
Alexander Eremin ◽  
Valentina Tarakanova ◽  
Elena Gurkovskaya ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Elevated Temperatures ◽  
Drying Shrinkage ◽  
Large Mass ◽  
Vacuum Drying ◽  
Surface Layers ◽  
The Difference ◽  
Increasing Temperature ◽  
Vacuum Dehydration ◽  
Shrinkage Coefficient

The work is devoted to the study of the shrinkage phenomena during the vacuum dehydration of the cheese varieties “Sovetskiy” and “Gollandskiy”. During the research, the dependences of the cheese shrinkage coefficient on the initial mass fraction of moisture were obtained. It was found that when the mass fraction of the cheese moisture increases, an increase in the shrinkage coefficient of the product occurs. The greatest increase in the cheese shrinkage coefficient is observed when the mass fraction of moisture is more than 50%. It was established that with increasing temperature and heat load, the moisture content on the cheese surface rapidly decreases, while in the central layers it changes more slowly. Shrinkage at elevated temperatures is less; however, dry cheese has a large mass fraction of moisture. It was found that an increase in the difference in the mass fraction of moisture between the inner and surface layers is accompanied by an increase in the difference between the actual shrinkage and possible shrinkage corresponding to the amount of liquid removed. The coefficients of shrinkage in the volume of the “Sovetskiy” and “Gollandskiy” cheese varieties were calculated: they lie in the range of 0.017–0.004 and 0.006–0.003, respectively. The dependences of the cheese shrinkage coefficients on the drying layer thickness, shape and size of grinding were obtained. Keywords: cheeses, vacuum drying, shrinkage

scholarly journals The Respiration of some Planktonic copepods II. The Effect Of Temperature

1953 ◽  
Vol 31 (3) ◽  
pp. 447-460 ◽  
Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont
Keyword(s):  
Respiratory Rate ◽  
The Body ◽  
The Other ◽  
Effect Of Temperature ◽  
Acartia Clausi ◽  
Temora Longicornis ◽  
Different Temperatures ◽  
Planktonic Copepods ◽  
The Difference ◽  
The Relationship

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.

scholarly journals Differences in physical symptoms between those with and without kidney disease: a comparative study across disease stages in a UK population

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Thomas J. Wilkinson ◽  
Daniel G. D. Nixon ◽  
Jared Palmer ◽  
Courtney J. Lightfoot ◽  
Alice C. Smith
Keyword(s):  
Kidney Disease ◽  
Early Stage ◽  
Symptom Burden ◽  
Final Analysis ◽  
Physical Symptoms ◽  
Disease Trajectory ◽  
High Prevalence ◽  
Comparative Group ◽  
The Difference ◽  
Disease Stages

Abstract Background Those living with kidney disease (KD) report extensive symptom burden. However, research into how symptoms change across stages is limited. The aims of this study were to 1) describe symptom burden across disease trajectory, and 2) to explore whether symptom burden is unique to KD when compared to a non-KD population. Methods Participants aged > 18 years with a known diagnosis of KD (including haemodialysis (HD) and peritoneal dialysis (PD)) and with a kidney transplant) completed the Leicester Kidney Symptom Questionnaire (KSQ). A non-KD group was recruited as a comparative group. Multinominal logistic regression modelling was used to test the difference in likelihood of those with KD reporting each symptom. Results In total, 2279 participants were included in the final analysis (age 56.0 (17.8) years, 48% male). The main findings can be summarised as: 1) the number of symptoms increases as KD severity progresses; 2) those with early stage KD have a comparable number of symptoms to those without KD; 3) apart from those receiving PD, the most frequently reported symptom across every other group, including the non-KD group, was ‘feeling tired’; and 4) being female independently increased the likelihood of reporting more symptoms. Conclusions Our findings have important implications for patients with KD. We have shown that high symptom burden is prevalent across the spectrum of disease, and present novel data on symptoms experienced in those without KD. Symptoms requiring the most immediate attention given their high prevalence may include pain and fatigue. Trial registration The study was registered prospectively as ISRCTN11596292.

Synthesis of Polyurethane Dendrimers and Transfer Properties of Dye

2013 ◽  
Vol 457-458 ◽  
pp. 65-71
Author(s):  
Jing Ru Jia
Keyword(s):  
Methyl Orange ◽  
Phase Transfer ◽  
Raw Materials ◽  
Toluene Diisocyanate ◽  
Polymerization Process ◽  
Process Conditions ◽  
Addition Polymerization ◽  
Different Temperatures ◽  
The Difference ◽  
Transfer Properties

The polyfunctional organic compounds 2- hydroxymethyl -1,4- butanediol (trihydric alcohol) and toluene diisocyanate -2, 4- diisocyanate (TDI) were taken as the raw materials in this study. A polyurethane dendrimer was synthesized by utilizing the difference in the reaction activity of two isocyanate groups of TDI at different temperatures. The polymerization process conditions were studied. The addition polymerization of para-position NCO groups occurred at 50 °C, and that of ortho NCO groups occurred at 90 °C. According to the structure of the dendrimer synthesized, methyl orange was used as the guest molecule. Consequently, the aqueous methyl orange showed a phase transfer. With the increase of dendrimer concentration, the transfer rate of methyl orange increased.

ON THE SURVIVAL AND METABOLISM OF NORMAL AND HYPOTHERMIC PRE-VIABLE HUMAN FOETUSES

1961 ◽  
Vol 23 (1) ◽  
pp. 69-77 ◽  
Author(s):  
S. KULLANDER ◽  
B. SUNDÉN
Keyword(s):  
Body Temperature ◽  
Survival Time ◽  
Glycogen Content ◽  
Adrenal Glands ◽  
Early Stage ◽  
The Body ◽  
Protein Nitrogen ◽  
Different Temperatures ◽  
Human Foetuses ◽  
General Reduction

SUMMARY A total of twenty-three human pre-viable foetuses (7–400 g.) were removed by abdominal hysterotomy (legal abortions) and studied during survival in an anoxic state at different temperatures. The duration of survival, as judged by ECG waves, at 37° c was about 3 hr.; it was longer for female foetuses than for males, and longer for large foetuses than for small ones. General reduction of the body-temperature to 4° c during periods varying between 30 min. and 6 hr. with subsequent rewarming to and maintenance at 37° c increased the survival time by a further 1–2 hr. The blood sugar did not decrease either during the period of survival or during hypothermia, but the non-protein nitrogen increased, while acidosis and hyperkalaemia developed. The glycogen content of the liver decreased during the anoxic period of survival and diminished further during hypothermia. The adrenal glands produced adrenaline in addition to noradrenaline during the anoxic phase, and this may occur in a very early stage of intrauterine life.

The Influence of Different Subbase Materials on the Crack of Cement Stabilized Macadam Base during Construction

2012 ◽  
Vol 591-593 ◽  
pp. 955-959 ◽  
Author(s):  
Xiao Feng Liao ◽  
Fen Xiao ◽  
Zhong Da Chen ◽  
Lei Xing
Keyword(s):  
Tensile Stress ◽  
Shrinkage Strain ◽  
Mechanical Parameters ◽  
Tensile Stresses ◽  
Shrinkage Crack ◽  
Dry Shrinkage ◽  
Base Course ◽  
Shrinkage Coefficient ◽  
Crack Space

According to actual axle load data and the measured mechanical parameters of cement stabilized macadam material with different cement dosages, the bottom tensile stresses of different subbase structures are calculated and the results show that: to graded gravel subbase, the weight of construction vehicle is inadvisable to be more than 35t and the cement dosage of base course shall be more than 3.0%; and, the maximum bottom tensile stress of graded gravel subbase shall be much more than that of lime-flyash soil subbase. According to the measured dry shrinkage strain and dry shrinkage coefficient, the dry shrinkage crack space of base course is analyzed and the results show that: under the same cement dosage, the crack space of the base course with graded gravel subbase is smaller than that of lime-flyash soil subbase; with the increase of cement dosage, the crack space of base course increase first and then decrease, and when the cement dosage is 3.5%, the dry shrinkage strain and dry shrinkage coefficient is minimum and the crack space of base course is maximum.

scholarly journals V. Electrolytic conduction in solids.—First example. hot glass

1875 ◽  
Vol 23 (156-163) ◽  
pp. 463-464 ◽  
Keyword(s):  
Different Temperatures ◽  
The Difference ◽  
Voltaic Cell

Many years ago I projected an experiment to test the voltaic relations between different metals with glass substituted for the electrolytic liquid of an ordinary simple voltaic cell, and with so high a temperature that the glass would have conducting-power sufficient to allow induction through it to rule the difference of potentials between the two metals. Imperfect instrumental arrangements, and want of knowledge of the temperature at which glass would have sufficient conductivity to give satisfactory results, have hitherto prevented me from carrying out the proposed investigation. The quadrant electrometer has supplied the first of these deficiencies, and Mr. Perry’s recent experiments on the conductivity of glass at different temperatures the second. The investigation has now been resumed; and in a preliminary experiment I have already obtained a very decided result.

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