The crystallization has significant influence on fluidity of slag and slag discharge of entrained-flow-bed(EFB) gasifier. The crystallization characteristics and fluidity of five synthetic slags with different MgO/CaO...The crystallization has significant influence on fluidity of slag and slag discharge of entrained-flow-bed(EFB) gasifier. The crystallization characteristics and fluidity of five synthetic slags with different MgO/CaO ratios prepared on the basis of the range of oxide contents of Zhundong coal ash were investigated in this study. The results show that with the MgO/CaO ratio increase, the initial crystallization temperature increases, and the main temperature range of crystallization ratio growth moves to higher temperature range gradually which causes Tp25(Tp25is the temperature corresponding to the viscosity of 25 Pa·s)to increase. Mg-rich crystals are formed preferentially than Ca-rich crystals when adding the same amount of MgO and CaO during cooling. The effective slagging operating temperature range decrease from 217 ℃ for the slag with a 0:4 MgO/CaO ratio to 44 ℃ for the slag with a 4:0 MgO/CaO ratio with the MgO/CaO ratio increase. The slags with 2:2 and 1:3 MgO/CaO ratios show similar effective slagging operating temperature range, Tp25and the temperature corresponding to the viscosity of 2 Pa·s.However, compared with the slag with a 1:3 MgO/CaO ratio, the crystallization ratio and rate of slag with a 2:2 MgO/CaO ratio are lower within lower temperature range(1300–1200 ℃), causing its lower critical viscosity temperature and wider actual operating temperature range. Of the five slags, the widest effective slagging operating temperature range and the lowest Tp25of the slag with a 0:4 MgO/CaO ratio due to its low crystallization ratio, and wider actual operating temperature range of the slag with a 2:2 MgO/CaO ratio make the two slags suitable for slag discharge of EFB gasifier.展开更多
To investigate the thixotropic fluidities, microstructures and mechanical properties of semi-solid AZ91D magnesium alloy during reheating, a self-made die set with channels of different sizes were used. The results sh...To investigate the thixotropic fluidities, microstructures and mechanical properties of semi-solid AZ91D magnesium alloy during reheating, a self-made die set with channels of different sizes were used. The results show that critical forming forces and maximal forming forces could be obtained and related to the holding times in the semi-solid forming process. In the holding time of 0-2700 s, with increasing the holding time, maximal forming force decreased sharply and critical forming force decreased slowly. In the whole thixotropic flowing process, the filling-in was steady and the surface fineness was good. The forming force increased when the slurry changed the flowing direction or flowed from the big-diameter chamber to the small-diameter one. The tensile strength and elongation to failure of the sample after holding time for 2700 s, compared to as-cast sample, are increased by approximately 42.7% and 180%, respectively, and the fractured surfaces presented dimple-like pattern.展开更多
After bilateral carotid artery occlusion for 30 minutes and reperfusion for 2 hours, distinct pathological changes presented in the cerebral cortex and cerebellum of rats. Compared with normal rats, nerve cell membran...After bilateral carotid artery occlusion for 30 minutes and reperfusion for 2 hours, distinct pathological changes presented in the cerebral cortex and cerebellum of rats. Compared with normal rats, nerve cell membrane fluidity significantly decreased in ischemia/reperfusion rats as detected by spin-labeling electron spin resonance, consistent with order parameter S and rotational correlation time TC measurements. Brain nerve cells from rats with ischemia/reperfusion injury were cultured with 1-100 mg/mL Buyang Huanwu decoction. Results showed that Buyang Huanwu decoction gradually increased membrane fluidity dose-dependently to normal levels, and eliminated hydroxide (OH') and superoxide (O2') free radicals dose-dependenUy. These findings suggest that Buyang Huanwu decoction can protect against cell membrane fluidity changes in rats with ischemia/ reperfusion injury by scavenging free radicals.展开更多
The influence of ultrasonic degassing process on fluidity and hardness of secondary Al7Si0.3Mg alloy castings was studied by Weibull analysis. This work makes a contribution about fluidity and hardness distribution of...The influence of ultrasonic degassing process on fluidity and hardness of secondary Al7Si0.3Mg alloy castings was studied by Weibull analysis. This work makes a contribution about fluidity and hardness distribution of secondary aluminum alloys with ultrasonic degassing phenomena using a two-parameter form of Weibull analysis. Results show that both hardness and fluidity of alloy are improved after the ultrasonic degassing process. Average efficiency of ultrasonic degassing on fluidity measurements is 31.71%, whereas on hardness values is 8.48%. The Brinell hardness of 45.7 and fluidity of 19.5 of Weibull modulus were achieved as the most reliable and reproducible after 45 s ultrasonic degassing process against 15 s and 30 s ultrasonic degassing processes. The value of 70.08 HB is obtained from ultrosonic degassing, which is equivalent to sand casting of primary Al7Si0.3Mg aluminum alloy, and the highest value of 56.4 cm for 45 s after ultrasonic degassing of fluidity was measured.展开更多
Effects of organosilane-modified PCE (OS-PCE) on the fluidity and the hydration properties of cement-fly ash (FA) composite binder were systematically analyzed.The experimental results show that OS-PCE possesses respe...Effects of organosilane-modified PCE (OS-PCE) on the fluidity and the hydration properties of cement-fly ash (FA) composite binder were systematically analyzed.The experimental results show that OS-PCE possesses respectively 36.98% and 36.67% higher saturated adsorption amount on cement and FA,in comparison with ordinary PCE,and can contribute to higher fluidity of cement-FA composite binder.The addition of OS-PCE retards hydration process of cement-FA composite binder proportionally with the dosage of OS-PCE,but promotes the hydration kinetics of the composite binder.The reactivity enhancement is attributed to the well-dispersed FA by OS-PCE,which provides more nucleation sites for the reaction of heterogeneous C-S-H and enhances the contact with water to react with CH forming pozzolanic C-S-H.Well-distributed hydration products are exhibited in the hardened binder added with OS-PCE,with a large number of hydrated gels uniformly fill in the pores and gaps,which improves the compaction of the hardened structure.展开更多
Differential effects of methamidophos and three pyrethroids on ATPase activity and membrane fluidity of mitochondria were investigated between the wolf spider(Pirata subpiraticus(Boes.et Str.))and the rice stem bo...Differential effects of methamidophos and three pyrethroids on ATPase activity and membrane fluidity of mitochondria were investigated between the wolf spider(Pirata subpiraticus(Boes.et Str.))and the rice stem borer(Chilo suppressalis(Walker)).Based on a comparison of LD_(50) values,the toxicities of the tested insecticides were higher to the wolf spider than to the rice stem borer.Cyhalothrin at 1×10^(–4) mmol L^(–1) caused inhibition of the mitochondrial Na~+-K~+-ATPase and Ca^(2+)-Mg^(2+)-ATPase activities,and it’s inhibitions on Na+-K+-ATPase and Ca^(2+)-Mg^(2+)-ATPase activities were significantly higher in the wolf spider(44 and 28%)than in the rice stem borer(19 and 11%).Methamidophos at 1×10^(–4) mmol L^(–1) decreased Ca^(2+)-Mg^(2+)-ATPase activity by 16 and 27%in the wolf spider and the rice stem borer,respectively,but no significant effect on the specific activity of Na+-K+-ATPase was observed.The DPH(1,6-diphenyl-1,3,5-hexatriene)fluorescence polarization values of mitochondrial membranes were not significantly affected by methamidophos in either species.However,cyhalothrin and alpha-cypermethrin induced the values of DPH polarization of mitochondrial membrane increasing with the concentration of cyhalothrin and alpha-cypermethrin from 20 to 100μmol L^(–1) in the rice stem borer and the wolf spider.Effect of ethofenprox on fluidity of the wolf spider and the rice stem borer was contrary.These results suggest that both inhibition of membrane ATPase and changes of membrane fluidity could be appended to the action mechanisms of pyrethroid insecticides.展开更多
The application of ultrasonic vibration to the casting process can be realized through mould(die)vibration.However,the resonant vibration of the mould is always accompanied by a non-uniform vibration distribution at d...The application of ultrasonic vibration to the casting process can be realized through mould(die)vibration.However,the resonant vibration of the mould is always accompanied by a non-uniform vibration distribution at different parts,which may induce a complex liquid flow and affect the casting fluidity during the mould filling process.The influence of non-uniform ultrasonic vibration on the fluidity of liquid AlSi9Cu3 alloy was studied by mould vibration with different vibration gradients.It is found that ultrasonic mould vibration can generate two opposite effects on the casting fluidity:the first,ultrasonic cavitation in melt induced by mould vibration promotes the casting fluidity;the second,the non-uniform mould vibration can induce a melt flow toward the weak vibration areas and turbulence there,consequently decreasing the casting fluidity.When the melt flow and turbulence are violent enough to offset the promoting effect of cavitation on fluidity,the ultrasonic vibration will finally induce a resultant decrease of casting fluidity.The decreasing effect is proportional to the vibration gradient.展开更多
In the present study, the effects of mold temperature, superheat, mold thickness, and Mg_2Si amount on the fluidity of the Al-Mg_2Si as-cast in-situ composites were investigated using the mathematical models. Composit...In the present study, the effects of mold temperature, superheat, mold thickness, and Mg_2Si amount on the fluidity of the Al-Mg_2Si as-cast in-situ composites were investigated using the mathematical models. Composites with different amounts of Mg_2Si were fabricated, and the fluidity and microstructure of each were then analyzed. For this purpose, the experiments were designed using a central composite rotatable design, and the relationship between parameters and fluidity were developed using the response surface method. In addition, optical and scanning electron microscopes were used for microstructural observation. The ANOVA shows that the mathematical models can predict the fluidity accurately. The results show that by increasing the mold temperature from 25℃ to 200℃, superheat from 50℃ to 250℃, and thickness from 3 mm to 12 mm, the fluidity of the composites decreases, where the mold thickness is more effective than other factors. In addition, the higher amounts of Mg_2Si in the range from 15 wt.% to 25 wt.% lead to the lower fluidity of the composites. For example, when the mold temperature, superheat, and thickness are respectively 100℃, 150℃, and 7 mm, the fluidity length is changed in the range of 11.9 cm to 15.3 cm. By increasing the amount of Mg_2Si, the morphology of the primary Mg_2Si becomes irregular and the size of primary Mg_2Si is increased. Moreover, the change of solidification mode from skin to pasty mode is the most noticeable microstructural effect on the fluidity.展开更多
The effect of fluidity on open cell AZ31 metal foam samples fabricated using a solid state space holder method was investigated.Granule was fabricated by plaster powder and perlite powder.Granules were sieved which co...The effect of fluidity on open cell AZ31 metal foam samples fabricated using a solid state space holder method was investigated.Granule was fabricated by plaster powder and perlite powder.Granules were sieved which compacted layer by layer in casting mold.Preforms which made by granules were then heated to 200℃,300℃,400℃,500℃ under a rough(mechanical)vacuum before pressure infiltration with AZ31 Mg alloy.Samples were infiltrated using vacuum pressure values range of 8-14 KPa.The conditions of pressure and temperature were performed in order to get different fluidity on manufacturer of open cell AZ31 metal foam specimen quantity.It is found that the fluidity plays significant role to determine the open cell AZ31 alloy foam.The fluidity is affected by preheat temperature and infiltration vacuum pressure.The macrostructure,the distribution of the pores,microstructure,infiltration length,and porosity were investigated.展开更多
Through adding different additional water use,the compressive strength,splitting tensile strength and fluidity of recycled concrete of three aggregate combination forms were studied by experiment respectively.The expe...Through adding different additional water use,the compressive strength,splitting tensile strength and fluidity of recycled concrete of three aggregate combination forms were studied by experiment respectively.The experimental results show that with the increase of adding additional water use,the compressive strength and splitting tensile strength of recycled coarse aggregate concrete decrease,but that of recycled fine aggregate concrete and recycled all aggregate concrete increase firstly then decrease.When additional water use is added more 15% or 20% than that of basic ordinary concrete,the recycled coarse aggregate concrete and fine one can get pretty good fluidity.When it is added more 30%,the recycled all aggregate concrete has fluidity that is just satisfied.展开更多
BACKGROUND The therapeutic potential of mesenchymal stem cells(MSCs)in the form of threedimensional spheroids has been extensively demonstrated.The underlying mechanisms for the altered cellular behavior of spheroids ...BACKGROUND The therapeutic potential of mesenchymal stem cells(MSCs)in the form of threedimensional spheroids has been extensively demonstrated.The underlying mechanisms for the altered cellular behavior of spheroids have also been investigated.Cell membrane fluidity is a critically important physical property for the regulation of cell behavior,but it has not been studied for the spheroid-forming cells to date.AIM To explore the association between cell membrane fluidity and the morphological changes of MSC spheroids on the surface of biomaterials to elucidate the role of membrane fluidity during the spheroid-forming process of MSCs.METHODS We generated three-dimensional(3D)MSC spheroids on the surface of various culture substrates including chitosan(CS),CS-hyaluronan(CS-HA),and polyvinyl alcohol(PVA)substrates.The cell membrane fluidity and cell morphological change were examined by a time-lapse recording system as well as a highresolution 3D cellular image explorer.MSCs and normal/cancer cells were prestained with fluorescent dyes and co-cultured on the biomaterials to investigate the exchange of cell membrane during the formation of heterogeneous cellular spheroids.RESULTS We discovered that vesicle-like bubbles randomly appeared on the outer layer of MSC spheroids cultured on different biomaterial surfaces.The average diameter of the vesicle-like bubbles of MSC spheroids on CS-HA at 37℃ was approximately 10μm,smaller than that on PVA substrates(approximately 27μm).Based on time-lapse images,these unique bubbles originated from the dynamic movement of the cell membrane during spheroid formation,which indicated an increment of membrane fluidity for MSCs cultured on these substrates.Moreover,the membrane interaction in two different types of cells with similar membrane fluidity may further induce a higher level of membrane translocation during the formation of heterogeneous spheroids.CONCLUSION Changes in cell membrane fluidity may be a novel path to elucidate the complicated physiological alterations in 3D spheroid-forming cells.展开更多
BACKGROUND: The fluidity of cell membrane can be affected by various factors. Many experiments have confirmed that the ischemia/reperfusion of organic tissue can increase the contents of free radicals, which lead to h...BACKGROUND: The fluidity of cell membrane can be affected by various factors. Many experiments have confirmed that the ischemia/reperfusion of organic tissue can increase the contents of free radicals, which lead to high rigidity and low fluidity of cell membrane, and the conditions can be changed by Chuanxiongqin. OBJECTIVE: To observe the effect and mechanism of Chuanxiongqin hydrochloride on the fluidity of brain cell membrane in rat models of ischemia/reperfusion. DESIGN: A completely randomized controlled animal trial. SETTINGS: Institute of Brain Sciences; Department of Physiology, Medical College, Datong University. MATERIALS: Twenty male grade Ⅰ Wistar rats of 170-220 g were randomly divided into model group (n =10) and control group (n =10). Chuanxiongqin hydrochloride (molecular mass was 172.2) was purchased from the National Institute for the Control of Pharmaceutical and Biological Products (batch number: 0817-9803); Spin labelers: 5-doxyl-stearlic acid methylester (5DS), 16-doxyl-stearlic acid methylester (16DS), xanthine, xanthine oxidase (XOD) and 5,5-dimeth-1-pyrroline- N-oxide (DMPO) from Sigma Company; Bruker ESP 300 electron paramagnetic resonance (EPR) spectrometer by Bruker Company (Germany). METHODS: The experiments were carried out in the State Key Laboratory of Natural and Biomimetic Drugs, Peking University from June 2001 to July 2002. In the model group, rats were made into models of cerebral ischemia by 30-minute ligation and 2-hour reperfusion of common carotid arteries; The rats in the control group were not made into models. The order parameter (S) and rotational correlation time (τc) were detected with the ESR spectrometer by means of spin labeling. The greater the S and τc, the smaller the fluidity. Meanwhile, the clearance rate of free radicals was detected with ESR spin trapping. The measurement data were compared using the t test. MAIN OUTCOME MEASURES: The S, τc and clearance rates of O2 · and OH· free radicals were compared between the model group and control group. RESULTS: The S and τc in the model group [0.738 4±0.003 5; (8.472±0.027)×10-10 s/circle] were obviously different from those in the control group [0.683 9±0.008 3; (7.945±0.082)×10-10 s/circle, t =5.731, 5.918, P < 0.05], which suggested that ischemia/reperfusion injury decreased the fluidity of brain cell membrane. After adding Chuanxiongqin hydrochloride, there were no obvious differences between the model group [0.688 5±0.030 5; (7.886±0.341)×10-10 s/circle] and control group (P > 0.05), indicating that Chuanxiongqin hydrochloride could recover the fluidity of brain cell membrane after ischemia/reperfusion injury close to the level in the normal control group. Chuanxiongqin hydrochloride could directly scavenge the O2 · and OH· free radicals, and the maximal clearance rates were 83.92% and 44.99% respectively. CONCLUSION: Chuanxiongqin hydrochloride increases the fluidity of membrane of ischemia-injured brain cell by scavenging both O2 ·and OH· free radicals.展开更多
There is evidence showing that increased levels of oxidative stress and C-reactive protein (CRP) might be associated with obesity, hypertension, atherosclerosis and other cardiovascular diseases. This study was undert...There is evidence showing that increased levels of oxidative stress and C-reactive protein (CRP) might be associated with obesity, hypertension, atherosclerosis and other cardiovascular diseases. This study was undertaken to investigate possible relationships among plasma 8-iso-prostaglandin F2α (8-iso-PG F2α: an index of oxidative stress), high-sensitivity (hs)-CRP and membrane fluidity (a reciprocal value of microviscosity) in hypertensive and normotensive men using an electron spin resonance (ESR)-method. The order parameter (S) for the spin-label agents (5-nitroxide stearate) of red blood cell (RBC) membranes in the ESR spectra was significantly higher in hypertensive men than in normotensive men, indicating that membrane fluidity was decreased in hypertensive men. Both plasma 8-iso-PG F2α and hs-CRP levels were significantly increased in hypertensive men compared with normotensive men. In addition, plasma plasma 8-iso-PG F2α levels were correlated with plasma hs-CRP levels. In contrast, plasma nitric oxide (NO)-metabolites were lower in hypertensive men than in normotensive men, and inversely correlated with plasma 8-iso-PG F2α and hs-CRP. The order parameter(S) of RBCs was correlated with plasma 8-iso-PG F2α and plasma hs-CRP, and inversely correlated with plasma NO-metabolites, suggesting that reduced membrane fluidity of RBCs might be associated with increased oxidative stress, inflammation and endothelial dysfunction. Multivariate regression analysis also showed that, after adjusting for general risk factors, both plasma 8-iso-PG F2α and hs-CRP were significant determinants of membrane fluidity of RBCs. The ESR suggests that associations of oxidative stress and inflammation might have a close correlation with impaired rheologic behavior of RBCs and microcirculatory dysfunction in hypertensive men.展开更多
The effects of processing variables on the fluidity of hypereutectic Al-Si alloy melt during squeeze casting were investigated.The maximum fluidity of Al-16.0%Si alloy during squeeze casting was obtained under the app...The effects of processing variables on the fluidity of hypereutectic Al-Si alloy melt during squeeze casting were investigated.The maximum fluidity of Al-16.0%Si alloy during squeeze casting was obtained under the applied pressure of 30 MPa.The fluidity increased with superheat.The fluidity increased with silicon content in the range from 12.0% to 20.0%.That was decreased respectively by eutectic modification and primary silicon refinement.展开更多
Objective To study the effects of different concentrations of Quercetin on nitric oxide (NO) production and membrane fluidity of the injured human umbilical vein vascular endothelial cell line(ECV 304) with hypoxia...Objective To study the effects of different concentrations of Quercetin on nitric oxide (NO) production and membrane fluidity of the injured human umbilical vein vascular endothelial cell line(ECV 304) with hypoxia and the lack of glucose. Methods The experiments were performed in the culture of ECV 304 injured with hypoxia and the lack of glucose in vitro. The releases of intracellular lactate dehydrogenase(LDH) of ECV 304 was measured with automatic biochemistry analysis. NO level of ECV 304 was monitored with colorimetry. The membrane fluidity of ECV 304 was measured with the fluorescence polarization method. Results After ECV 304 was cultured in hypoxia and the the lack of glucose for 24 hours, the release of LDH and the membrane fluidity were increased significantly; NO level was decreased. Preincubation of ECV 304 with 20, 80,160 μ mol·L -1 of Quercetin for 24 hours reduced LDH activity, membrane fluidity and increased the level of NO in hypoxia and the lack of glucose induced ECV 304. Conclusion These results demonstrate that Quercetin can produce the protective effect on hypoxia and the lack of glucose induced injury of ECV 304 by increasing release of NO and changing membrane fluidity.展开更多
The influence of SiO2 on bonding phase fluidity was studied by measuring the projected area of tablets prepared using mixtures of fine iron ore and chemical reagents after sintering. The microstructure of samples was ...The influence of SiO2 on bonding phase fluidity was studied by measuring the projected area of tablets prepared using mixtures of fine iron ore and chemical reagents after sintering. The microstructure of samples was observed by optical microscope and SEM. Moreover, the relationship between SiO2 and bonding phase fluidity and microstructure was analyzed by CaO-Fe2O3-SiO2 system 1 300℃ isothermal section diagram. The main experimental conditions are as follows: in the composition of the bonding phase,CaO is 10%, 15% ,and 20%; SiO2 is 2% and 6% ; sintering temperature is 1 250, 1 300 and 1 350 ℃ ; the sample cooling rate is quick. The results of the study show that.① The fluidity of the binding phase decreases with the increase of SiO2 content. Moreover,fluidity increases as the sintering temperature increases; however, when the CaO content is 10% (relatively low proportion), the lifting temperature has limited effect on fluidity improvement. ② The hematite proportion of the microstructure increases as the SiO2 content increases. ③ When SiO2 content increases, the solid phase ratio in the bonding phase grows,while the liquid phase ratio diminishes. Moreover the extension of the SiO2 content in the liquid phase is larger than that in the solid phase.展开更多
In order to investigate the effect of salvia miltiorrhiza hunge(SMB)on the plasma membrane fluidity and the relationship between the lipid peroxidation and the Plasma membrane fluidityin cultured human fetdal hepatocy...In order to investigate the effect of salvia miltiorrhiza hunge(SMB)on the plasma membrane fluidity and the relationship between the lipid peroxidation and the Plasma membrane fluidityin cultured human fetdal hepatocytes,the plasma membrane fluidity,using 1,6-dipheny-1,3,5-hexatriene(DPH)as a fluorescence probe, malondialdehyde(MDA)production as well as alanine aminotransferase(ALT)release of human fetal hepatocytes cultured in Presence of carbon tetrachloride(CCl4)or SMB puls CCl4 were estimated. In the cultured hepatocytes injured by CCl4,significant increments of the MDA production and the ALT release,and significant decrease in the plasma membrane fluidity were observed.when the culture medium was supplied with SMB prior to the additionof CCl4,the CCl4 induced increments in MDA production and ALT release was suppressed signifi cantly and a concomitant raise of plasma membrane fluidity towards normal occurred.The resultssuggested that SMB could suppress the lipid peroxidation in bepatocytes,thereby normal membranefluidity might be retained.展开更多
The ability of cell to modulate the fluidity of plasma membrane was crucial to the survival of microorganism at low temperature.Plasma membrane proteins,fatty acids and carotenoids profiles of Antarctic psychrophilc y...The ability of cell to modulate the fluidity of plasma membrane was crucial to the survival of microorganism at low temperature.Plasma membrane proteins,fatty acids and carotenoids profiles of Antarctic psychrophilc yeast Rhodotorula sp.NJ298 were investigated at-3 ℃,0 ℃ and 8 ℃.The results showed that plasma membrane protein content was greater at-3 ℃ than that at 8 ℃,and a unique membrane polypeptide composition with an apparent molecular mass of 94.7 kDa was newly synthesized with SDS-PAGE analysis;GC analysis showed that the main changes of fatty acids were the percentage of unsaturated fatty acids(C18:1 and C18:2) and shorter chain saturated fatty acid(C10:0) increased along with the decrease of the culture temperature from 8 ℃ to-3 ℃;HPLC analysis indicated that astaxanthin was the major functional carotenoids of the plasma membrane,percentage of which increased from 54.6±1.5% at 8 ℃ to 81.9±2.1% at-3 ℃.However the fluidity of plasma membrane which was determined by measuring fluorescence anisotropy was similar at-3 ℃,0 ℃ and 8 ℃.Hence these changes in plasma membrane’s characteristics were involved in the cellular cold-adaptation by which NJ298 could maintain normal plasma membrane fluidity at near-freezing temperature.展开更多
Biological membranes are preferentially composed of lipids and proteins, and it is assumed that mainly the proteins are responsible for their functional properties. Nevertheless, during the last years, the contributio...Biological membranes are preferentially composed of lipids and proteins, and it is assumed that mainly the proteins are responsible for their functional properties. Nevertheless, during the last years, the contribution of the plain lipid matrix and its physico-chemical parameters to membrane functionality has been shown to be of high relevance. This is also correct for the gravity dependence of cells and organisms which is well accepted since long for a wide range of biological systems. Thus, the question must be asked, whether, and how far plain lipid membranes are affected by gravity directly. In this study we show that the fluidity (viscosity) of plain lipid membranes, as well as that of cell membranes, is gravity dependent, using a multipurpose 96-well plate reader in the fluorescence polarization anisotropy mode in a parabolic flight mission. Plain lipid vesicles and cells from a human cancer cell line have been used in these experiments. Necessarily, membrane-integrated proteins should be affected by this in their function. As a consequence any living cell will be able to sense at least basically gravity.展开更多
Fluidity of cellular membranes is essential for life. Two possibilities are known to keep human membranes fluid: unsaturated fatty acids and cholesterol. Whereas liver cells can synthesize cholesterol, unsaturated fat...Fluidity of cellular membranes is essential for life. Two possibilities are known to keep human membranes fluid: unsaturated fatty acids and cholesterol. Whereas liver cells can synthesize cholesterol, unsaturated fatty acids are essential. Life style in Western civilization leads to deprivation of essential fatty acids, to elevated serum-cholesterol-levels and to autoimmunity. Here the hypothesis is presented, and explains the relationship: deprivation of essential fatty acids lead to imminent quasi-crystallization of the membrane. Serum cholesterol-levels are elevated. Incorporation of cholesterol into membranes enhancing fluidity again, is able to repair the effect. At saturation, repair fails. Quasi-crystallization occurs. Proteins tilt into another conformation. This has not been learned during the “self” recognition process of the immune system during the embryonic phase. Immune system attacks the new conformation as “non-self”, autoimmunity emerges.展开更多
基金supported by the National Natural Science Foundation of China(21878082).
文摘The crystallization has significant influence on fluidity of slag and slag discharge of entrained-flow-bed(EFB) gasifier. The crystallization characteristics and fluidity of five synthetic slags with different MgO/CaO ratios prepared on the basis of the range of oxide contents of Zhundong coal ash were investigated in this study. The results show that with the MgO/CaO ratio increase, the initial crystallization temperature increases, and the main temperature range of crystallization ratio growth moves to higher temperature range gradually which causes Tp25(Tp25is the temperature corresponding to the viscosity of 25 Pa·s)to increase. Mg-rich crystals are formed preferentially than Ca-rich crystals when adding the same amount of MgO and CaO during cooling. The effective slagging operating temperature range decrease from 217 ℃ for the slag with a 0:4 MgO/CaO ratio to 44 ℃ for the slag with a 4:0 MgO/CaO ratio with the MgO/CaO ratio increase. The slags with 2:2 and 1:3 MgO/CaO ratios show similar effective slagging operating temperature range, Tp25and the temperature corresponding to the viscosity of 2 Pa·s.However, compared with the slag with a 1:3 MgO/CaO ratio, the crystallization ratio and rate of slag with a 2:2 MgO/CaO ratio are lower within lower temperature range(1300–1200 ℃), causing its lower critical viscosity temperature and wider actual operating temperature range. Of the five slags, the widest effective slagging operating temperature range and the lowest Tp25of the slag with a 0:4 MgO/CaO ratio due to its low crystallization ratio, and wider actual operating temperature range of the slag with a 2:2 MgO/CaO ratio make the two slags suitable for slag discharge of EFB gasifier.
文摘To investigate the thixotropic fluidities, microstructures and mechanical properties of semi-solid AZ91D magnesium alloy during reheating, a self-made die set with channels of different sizes were used. The results show that critical forming forces and maximal forming forces could be obtained and related to the holding times in the semi-solid forming process. In the holding time of 0-2700 s, with increasing the holding time, maximal forming force decreased sharply and critical forming force decreased slowly. In the whole thixotropic flowing process, the filling-in was steady and the surface fineness was good. The forming force increased when the slurry changed the flowing direction or flowed from the big-diameter chamber to the small-diameter one. The tensile strength and elongation to failure of the sample after holding time for 2700 s, compared to as-cast sample, are increased by approximately 42.7% and 180%, respectively, and the fractured surfaces presented dimple-like pattern.
基金supported by the Doctor Foundation(2008) in Shanxi Datong University
文摘After bilateral carotid artery occlusion for 30 minutes and reperfusion for 2 hours, distinct pathological changes presented in the cerebral cortex and cerebellum of rats. Compared with normal rats, nerve cell membrane fluidity significantly decreased in ischemia/reperfusion rats as detected by spin-labeling electron spin resonance, consistent with order parameter S and rotational correlation time TC measurements. Brain nerve cells from rats with ischemia/reperfusion injury were cultured with 1-100 mg/mL Buyang Huanwu decoction. Results showed that Buyang Huanwu decoction gradually increased membrane fluidity dose-dependently to normal levels, and eliminated hydroxide (OH') and superoxide (O2') free radicals dose-dependenUy. These findings suggest that Buyang Huanwu decoction can protect against cell membrane fluidity changes in rats with ischemia/ reperfusion injury by scavenging free radicals.
文摘The influence of ultrasonic degassing process on fluidity and hardness of secondary Al7Si0.3Mg alloy castings was studied by Weibull analysis. This work makes a contribution about fluidity and hardness distribution of secondary aluminum alloys with ultrasonic degassing phenomena using a two-parameter form of Weibull analysis. Results show that both hardness and fluidity of alloy are improved after the ultrasonic degassing process. Average efficiency of ultrasonic degassing on fluidity measurements is 31.71%, whereas on hardness values is 8.48%. The Brinell hardness of 45.7 and fluidity of 19.5 of Weibull modulus were achieved as the most reliable and reproducible after 45 s ultrasonic degassing process against 15 s and 30 s ultrasonic degassing processes. The value of 70.08 HB is obtained from ultrosonic degassing, which is equivalent to sand casting of primary Al7Si0.3Mg aluminum alloy, and the highest value of 56.4 cm for 45 s after ultrasonic degassing of fluidity was measured.
基金Funded by the Natural Science Foundation of China(51808369)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(18KJB560016)+4 种基金the Opening Project of State Key Laboratory of Green Building Materials(YA-615)the State Key Laboratory of Silicate Building Materials(SYSJJ2018-09)Hubei Key Laboratory of Water System Science for Sponge City Construction(2019-01)the Construction System Science and Technology Project of Jiangsu Province(2018ZD049)the Natural Science Foundation of Suzhou University of Science and Technology(XKQ2018009)。
文摘Effects of organosilane-modified PCE (OS-PCE) on the fluidity and the hydration properties of cement-fly ash (FA) composite binder were systematically analyzed.The experimental results show that OS-PCE possesses respectively 36.98% and 36.67% higher saturated adsorption amount on cement and FA,in comparison with ordinary PCE,and can contribute to higher fluidity of cement-FA composite binder.The addition of OS-PCE retards hydration process of cement-FA composite binder proportionally with the dosage of OS-PCE,but promotes the hydration kinetics of the composite binder.The reactivity enhancement is attributed to the well-dispersed FA by OS-PCE,which provides more nucleation sites for the reaction of heterogeneous C-S-H and enhances the contact with water to react with CH forming pozzolanic C-S-H.Well-distributed hydration products are exhibited in the hardened binder added with OS-PCE,with a large number of hydrated gels uniformly fill in the pores and gaps,which improves the compaction of the hardened structure.
基金supported by the National Basic Research Program of China(2012CB114103)
文摘Differential effects of methamidophos and three pyrethroids on ATPase activity and membrane fluidity of mitochondria were investigated between the wolf spider(Pirata subpiraticus(Boes.et Str.))and the rice stem borer(Chilo suppressalis(Walker)).Based on a comparison of LD_(50) values,the toxicities of the tested insecticides were higher to the wolf spider than to the rice stem borer.Cyhalothrin at 1×10^(–4) mmol L^(–1) caused inhibition of the mitochondrial Na~+-K~+-ATPase and Ca^(2+)-Mg^(2+)-ATPase activities,and it’s inhibitions on Na+-K+-ATPase and Ca^(2+)-Mg^(2+)-ATPase activities were significantly higher in the wolf spider(44 and 28%)than in the rice stem borer(19 and 11%).Methamidophos at 1×10^(–4) mmol L^(–1) decreased Ca^(2+)-Mg^(2+)-ATPase activity by 16 and 27%in the wolf spider and the rice stem borer,respectively,but no significant effect on the specific activity of Na+-K+-ATPase was observed.The DPH(1,6-diphenyl-1,3,5-hexatriene)fluorescence polarization values of mitochondrial membranes were not significantly affected by methamidophos in either species.However,cyhalothrin and alpha-cypermethrin induced the values of DPH polarization of mitochondrial membrane increasing with the concentration of cyhalothrin and alpha-cypermethrin from 20 to 100μmol L^(–1) in the rice stem borer and the wolf spider.Effect of ethofenprox on fluidity of the wolf spider and the rice stem borer was contrary.These results suggest that both inhibition of membrane ATPase and changes of membrane fluidity could be appended to the action mechanisms of pyrethroid insecticides.
基金supported by the Natural Science Foundation of Shandong province (ZR2021ME023)the Innovation Team Project of Jinan,China (2019GXRC035)
文摘The application of ultrasonic vibration to the casting process can be realized through mould(die)vibration.However,the resonant vibration of the mould is always accompanied by a non-uniform vibration distribution at different parts,which may induce a complex liquid flow and affect the casting fluidity during the mould filling process.The influence of non-uniform ultrasonic vibration on the fluidity of liquid AlSi9Cu3 alloy was studied by mould vibration with different vibration gradients.It is found that ultrasonic mould vibration can generate two opposite effects on the casting fluidity:the first,ultrasonic cavitation in melt induced by mould vibration promotes the casting fluidity;the second,the non-uniform mould vibration can induce a melt flow toward the weak vibration areas and turbulence there,consequently decreasing the casting fluidity.When the melt flow and turbulence are violent enough to offset the promoting effect of cavitation on fluidity,the ultrasonic vibration will finally induce a resultant decrease of casting fluidity.The decreasing effect is proportional to the vibration gradient.
文摘In the present study, the effects of mold temperature, superheat, mold thickness, and Mg_2Si amount on the fluidity of the Al-Mg_2Si as-cast in-situ composites were investigated using the mathematical models. Composites with different amounts of Mg_2Si were fabricated, and the fluidity and microstructure of each were then analyzed. For this purpose, the experiments were designed using a central composite rotatable design, and the relationship between parameters and fluidity were developed using the response surface method. In addition, optical and scanning electron microscopes were used for microstructural observation. The ANOVA shows that the mathematical models can predict the fluidity accurately. The results show that by increasing the mold temperature from 25℃ to 200℃, superheat from 50℃ to 250℃, and thickness from 3 mm to 12 mm, the fluidity of the composites decreases, where the mold thickness is more effective than other factors. In addition, the higher amounts of Mg_2Si in the range from 15 wt.% to 25 wt.% lead to the lower fluidity of the composites. For example, when the mold temperature, superheat, and thickness are respectively 100℃, 150℃, and 7 mm, the fluidity length is changed in the range of 11.9 cm to 15.3 cm. By increasing the amount of Mg_2Si, the morphology of the primary Mg_2Si becomes irregular and the size of primary Mg_2Si is increased. Moreover, the change of solidification mode from skin to pasty mode is the most noticeable microstructural effect on the fluidity.
文摘The effect of fluidity on open cell AZ31 metal foam samples fabricated using a solid state space holder method was investigated.Granule was fabricated by plaster powder and perlite powder.Granules were sieved which compacted layer by layer in casting mold.Preforms which made by granules were then heated to 200℃,300℃,400℃,500℃ under a rough(mechanical)vacuum before pressure infiltration with AZ31 Mg alloy.Samples were infiltrated using vacuum pressure values range of 8-14 KPa.The conditions of pressure and temperature were performed in order to get different fluidity on manufacturer of open cell AZ31 metal foam specimen quantity.It is found that the fluidity plays significant role to determine the open cell AZ31 alloy foam.The fluidity is affected by preheat temperature and infiltration vacuum pressure.The macrostructure,the distribution of the pores,microstructure,infiltration length,and porosity were investigated.
基金Project(Xiangjianke(2007)No.425) supported by Scientific Research Fund of Hunan Provincial Construction DepartmentProject supported by the Youth Framework Teacher Fund of Xiangtan University(2006)
文摘Through adding different additional water use,the compressive strength,splitting tensile strength and fluidity of recycled concrete of three aggregate combination forms were studied by experiment respectively.The experimental results show that with the increase of adding additional water use,the compressive strength and splitting tensile strength of recycled coarse aggregate concrete decrease,but that of recycled fine aggregate concrete and recycled all aggregate concrete increase firstly then decrease.When additional water use is added more 15% or 20% than that of basic ordinary concrete,the recycled coarse aggregate concrete and fine one can get pretty good fluidity.When it is added more 30%,the recycled all aggregate concrete has fluidity that is just satisfied.
基金National Taiwan University Core Consortium,No.NTU-CC-110L892501Ministry of Science and Technology,No.MOST 110-2218-E-002-037.
文摘BACKGROUND The therapeutic potential of mesenchymal stem cells(MSCs)in the form of threedimensional spheroids has been extensively demonstrated.The underlying mechanisms for the altered cellular behavior of spheroids have also been investigated.Cell membrane fluidity is a critically important physical property for the regulation of cell behavior,but it has not been studied for the spheroid-forming cells to date.AIM To explore the association between cell membrane fluidity and the morphological changes of MSC spheroids on the surface of biomaterials to elucidate the role of membrane fluidity during the spheroid-forming process of MSCs.METHODS We generated three-dimensional(3D)MSC spheroids on the surface of various culture substrates including chitosan(CS),CS-hyaluronan(CS-HA),and polyvinyl alcohol(PVA)substrates.The cell membrane fluidity and cell morphological change were examined by a time-lapse recording system as well as a highresolution 3D cellular image explorer.MSCs and normal/cancer cells were prestained with fluorescent dyes and co-cultured on the biomaterials to investigate the exchange of cell membrane during the formation of heterogeneous cellular spheroids.RESULTS We discovered that vesicle-like bubbles randomly appeared on the outer layer of MSC spheroids cultured on different biomaterial surfaces.The average diameter of the vesicle-like bubbles of MSC spheroids on CS-HA at 37℃ was approximately 10μm,smaller than that on PVA substrates(approximately 27μm).Based on time-lapse images,these unique bubbles originated from the dynamic movement of the cell membrane during spheroid formation,which indicated an increment of membrane fluidity for MSCs cultured on these substrates.Moreover,the membrane interaction in two different types of cells with similar membrane fluidity may further induce a higher level of membrane translocation during the formation of heterogeneous spheroids.CONCLUSION Changes in cell membrane fluidity may be a novel path to elucidate the complicated physiological alterations in 3D spheroid-forming cells.
文摘BACKGROUND: The fluidity of cell membrane can be affected by various factors. Many experiments have confirmed that the ischemia/reperfusion of organic tissue can increase the contents of free radicals, which lead to high rigidity and low fluidity of cell membrane, and the conditions can be changed by Chuanxiongqin. OBJECTIVE: To observe the effect and mechanism of Chuanxiongqin hydrochloride on the fluidity of brain cell membrane in rat models of ischemia/reperfusion. DESIGN: A completely randomized controlled animal trial. SETTINGS: Institute of Brain Sciences; Department of Physiology, Medical College, Datong University. MATERIALS: Twenty male grade Ⅰ Wistar rats of 170-220 g were randomly divided into model group (n =10) and control group (n =10). Chuanxiongqin hydrochloride (molecular mass was 172.2) was purchased from the National Institute for the Control of Pharmaceutical and Biological Products (batch number: 0817-9803); Spin labelers: 5-doxyl-stearlic acid methylester (5DS), 16-doxyl-stearlic acid methylester (16DS), xanthine, xanthine oxidase (XOD) and 5,5-dimeth-1-pyrroline- N-oxide (DMPO) from Sigma Company; Bruker ESP 300 electron paramagnetic resonance (EPR) spectrometer by Bruker Company (Germany). METHODS: The experiments were carried out in the State Key Laboratory of Natural and Biomimetic Drugs, Peking University from June 2001 to July 2002. In the model group, rats were made into models of cerebral ischemia by 30-minute ligation and 2-hour reperfusion of common carotid arteries; The rats in the control group were not made into models. The order parameter (S) and rotational correlation time (τc) were detected with the ESR spectrometer by means of spin labeling. The greater the S and τc, the smaller the fluidity. Meanwhile, the clearance rate of free radicals was detected with ESR spin trapping. The measurement data were compared using the t test. MAIN OUTCOME MEASURES: The S, τc and clearance rates of O2 · and OH· free radicals were compared between the model group and control group. RESULTS: The S and τc in the model group [0.738 4±0.003 5; (8.472±0.027)×10-10 s/circle] were obviously different from those in the control group [0.683 9±0.008 3; (7.945±0.082)×10-10 s/circle, t =5.731, 5.918, P < 0.05], which suggested that ischemia/reperfusion injury decreased the fluidity of brain cell membrane. After adding Chuanxiongqin hydrochloride, there were no obvious differences between the model group [0.688 5±0.030 5; (7.886±0.341)×10-10 s/circle] and control group (P > 0.05), indicating that Chuanxiongqin hydrochloride could recover the fluidity of brain cell membrane after ischemia/reperfusion injury close to the level in the normal control group. Chuanxiongqin hydrochloride could directly scavenge the O2 · and OH· free radicals, and the maximal clearance rates were 83.92% and 44.99% respectively. CONCLUSION: Chuanxiongqin hydrochloride increases the fluidity of membrane of ischemia-injured brain cell by scavenging both O2 ·and OH· free radicals.
文摘There is evidence showing that increased levels of oxidative stress and C-reactive protein (CRP) might be associated with obesity, hypertension, atherosclerosis and other cardiovascular diseases. This study was undertaken to investigate possible relationships among plasma 8-iso-prostaglandin F2α (8-iso-PG F2α: an index of oxidative stress), high-sensitivity (hs)-CRP and membrane fluidity (a reciprocal value of microviscosity) in hypertensive and normotensive men using an electron spin resonance (ESR)-method. The order parameter (S) for the spin-label agents (5-nitroxide stearate) of red blood cell (RBC) membranes in the ESR spectra was significantly higher in hypertensive men than in normotensive men, indicating that membrane fluidity was decreased in hypertensive men. Both plasma 8-iso-PG F2α and hs-CRP levels were significantly increased in hypertensive men compared with normotensive men. In addition, plasma plasma 8-iso-PG F2α levels were correlated with plasma hs-CRP levels. In contrast, plasma nitric oxide (NO)-metabolites were lower in hypertensive men than in normotensive men, and inversely correlated with plasma 8-iso-PG F2α and hs-CRP. The order parameter(S) of RBCs was correlated with plasma 8-iso-PG F2α and plasma hs-CRP, and inversely correlated with plasma NO-metabolites, suggesting that reduced membrane fluidity of RBCs might be associated with increased oxidative stress, inflammation and endothelial dysfunction. Multivariate regression analysis also showed that, after adjusting for general risk factors, both plasma 8-iso-PG F2α and hs-CRP were significant determinants of membrane fluidity of RBCs. The ESR suggests that associations of oxidative stress and inflammation might have a close correlation with impaired rheologic behavior of RBCs and microcirculatory dysfunction in hypertensive men.
文摘The effects of processing variables on the fluidity of hypereutectic Al-Si alloy melt during squeeze casting were investigated.The maximum fluidity of Al-16.0%Si alloy during squeeze casting was obtained under the applied pressure of 30 MPa.The fluidity increased with superheat.The fluidity increased with silicon content in the range from 12.0% to 20.0%.That was decreased respectively by eutectic modification and primary silicon refinement.
文摘Objective To study the effects of different concentrations of Quercetin on nitric oxide (NO) production and membrane fluidity of the injured human umbilical vein vascular endothelial cell line(ECV 304) with hypoxia and the lack of glucose. Methods The experiments were performed in the culture of ECV 304 injured with hypoxia and the lack of glucose in vitro. The releases of intracellular lactate dehydrogenase(LDH) of ECV 304 was measured with automatic biochemistry analysis. NO level of ECV 304 was monitored with colorimetry. The membrane fluidity of ECV 304 was measured with the fluorescence polarization method. Results After ECV 304 was cultured in hypoxia and the the lack of glucose for 24 hours, the release of LDH and the membrane fluidity were increased significantly; NO level was decreased. Preincubation of ECV 304 with 20, 80,160 μ mol·L -1 of Quercetin for 24 hours reduced LDH activity, membrane fluidity and increased the level of NO in hypoxia and the lack of glucose induced ECV 304. Conclusion These results demonstrate that Quercetin can produce the protective effect on hypoxia and the lack of glucose induced injury of ECV 304 by increasing release of NO and changing membrane fluidity.
文摘The influence of SiO2 on bonding phase fluidity was studied by measuring the projected area of tablets prepared using mixtures of fine iron ore and chemical reagents after sintering. The microstructure of samples was observed by optical microscope and SEM. Moreover, the relationship between SiO2 and bonding phase fluidity and microstructure was analyzed by CaO-Fe2O3-SiO2 system 1 300℃ isothermal section diagram. The main experimental conditions are as follows: in the composition of the bonding phase,CaO is 10%, 15% ,and 20%; SiO2 is 2% and 6% ; sintering temperature is 1 250, 1 300 and 1 350 ℃ ; the sample cooling rate is quick. The results of the study show that.① The fluidity of the binding phase decreases with the increase of SiO2 content. Moreover,fluidity increases as the sintering temperature increases; however, when the CaO content is 10% (relatively low proportion), the lifting temperature has limited effect on fluidity improvement. ② The hematite proportion of the microstructure increases as the SiO2 content increases. ③ When SiO2 content increases, the solid phase ratio in the bonding phase grows,while the liquid phase ratio diminishes. Moreover the extension of the SiO2 content in the liquid phase is larger than that in the solid phase.
文摘In order to investigate the effect of salvia miltiorrhiza hunge(SMB)on the plasma membrane fluidity and the relationship between the lipid peroxidation and the Plasma membrane fluidityin cultured human fetdal hepatocytes,the plasma membrane fluidity,using 1,6-dipheny-1,3,5-hexatriene(DPH)as a fluorescence probe, malondialdehyde(MDA)production as well as alanine aminotransferase(ALT)release of human fetal hepatocytes cultured in Presence of carbon tetrachloride(CCl4)or SMB puls CCl4 were estimated. In the cultured hepatocytes injured by CCl4,significant increments of the MDA production and the ALT release,and significant decrease in the plasma membrane fluidity were observed.when the culture medium was supplied with SMB prior to the additionof CCl4,the CCl4 induced increments in MDA production and ALT release was suppressed signifi cantly and a concomitant raise of plasma membrane fluidity towards normal occurred.The resultssuggested that SMB could suppress the lipid peroxidation in bepatocytes,thereby normal membranefluidity might be retained.
文摘The ability of cell to modulate the fluidity of plasma membrane was crucial to the survival of microorganism at low temperature.Plasma membrane proteins,fatty acids and carotenoids profiles of Antarctic psychrophilc yeast Rhodotorula sp.NJ298 were investigated at-3 ℃,0 ℃ and 8 ℃.The results showed that plasma membrane protein content was greater at-3 ℃ than that at 8 ℃,and a unique membrane polypeptide composition with an apparent molecular mass of 94.7 kDa was newly synthesized with SDS-PAGE analysis;GC analysis showed that the main changes of fatty acids were the percentage of unsaturated fatty acids(C18:1 and C18:2) and shorter chain saturated fatty acid(C10:0) increased along with the decrease of the culture temperature from 8 ℃ to-3 ℃;HPLC analysis indicated that astaxanthin was the major functional carotenoids of the plasma membrane,percentage of which increased from 54.6±1.5% at 8 ℃ to 81.9±2.1% at-3 ℃.However the fluidity of plasma membrane which was determined by measuring fluorescence anisotropy was similar at-3 ℃,0 ℃ and 8 ℃.Hence these changes in plasma membrane’s characteristics were involved in the cellular cold-adaptation by which NJ298 could maintain normal plasma membrane fluidity at near-freezing temperature.
文摘Biological membranes are preferentially composed of lipids and proteins, and it is assumed that mainly the proteins are responsible for their functional properties. Nevertheless, during the last years, the contribution of the plain lipid matrix and its physico-chemical parameters to membrane functionality has been shown to be of high relevance. This is also correct for the gravity dependence of cells and organisms which is well accepted since long for a wide range of biological systems. Thus, the question must be asked, whether, and how far plain lipid membranes are affected by gravity directly. In this study we show that the fluidity (viscosity) of plain lipid membranes, as well as that of cell membranes, is gravity dependent, using a multipurpose 96-well plate reader in the fluorescence polarization anisotropy mode in a parabolic flight mission. Plain lipid vesicles and cells from a human cancer cell line have been used in these experiments. Necessarily, membrane-integrated proteins should be affected by this in their function. As a consequence any living cell will be able to sense at least basically gravity.
文摘Fluidity of cellular membranes is essential for life. Two possibilities are known to keep human membranes fluid: unsaturated fatty acids and cholesterol. Whereas liver cells can synthesize cholesterol, unsaturated fatty acids are essential. Life style in Western civilization leads to deprivation of essential fatty acids, to elevated serum-cholesterol-levels and to autoimmunity. Here the hypothesis is presented, and explains the relationship: deprivation of essential fatty acids lead to imminent quasi-crystallization of the membrane. Serum cholesterol-levels are elevated. Incorporation of cholesterol into membranes enhancing fluidity again, is able to repair the effect. At saturation, repair fails. Quasi-crystallization occurs. Proteins tilt into another conformation. This has not been learned during the “self” recognition process of the immune system during the embryonic phase. Immune system attacks the new conformation as “non-self”, autoimmunity emerges.