Isoméirsation cis–trans de l'azobenzène catalysée par l'iode. III

1974 ◽  
Vol 52 (10) ◽  
pp. 1868-1871 ◽  
Author(s):  
René Arnaud ◽  
Jacques Lemaire
Keyword(s):  
Liquid Phase ◽  
Rate Constant ◽  
Surface Effects ◽  
High Reactivity ◽  
Trans Isomerization ◽  
Low Concentrations ◽  
Very High

The cis–trans isomerization of azobenzene can be catalyzed by iodine. The rate constant for the reaction of cis-azobenzene with iodine atoms was determined as 2 ± 1 × 106 mol−1 1 s−1, i.e. a much larger value than that pertaining to other isomerizable systems. This very high reactivity of cis-azobenzene allowed the demonstration of surface effects which were unexpected in the liquid phase. A method for estimating low concentrations of iodine atoms can be based on this catalyzed isomerization. [Journal translation]

Small-volume vitrification and rapid warming yield high survivals of one-cell rat embryos in cryotubes

2021 ◽  
Author(s):  
Yasuyoshi Fukuda ◽  
Misako Higashiya ◽  
Takahiro Obata ◽  
Keita Basaki ◽  
Megumi Yano ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Small Volume ◽  
Sucrose Solution ◽  
High Concentration ◽  
Rat Embryos ◽  
Low Concentrations ◽  
Intracellular Ice Formation ◽  
Intracellular Ice ◽  
Warming Rate ◽  
Very High

Abstract To cryopreserve cells, it is essential to avoid intracellular ice formation during cooling and warming. One way to achieve this is to convert the water inside the cells into a non-crystalline glass. It is currently believed that to accomplish this vitrification, the cells must be suspended in a very high concentration (20–40%) of a glass-inducing solute, and subsequently cooled very rapidly. Herein, we report that this belief is erroneous with respect to the vitrification of one-cell rat embryos. In the present study, one-cell rat embryos were vitrified with 5 μL of EFS10 (a mixture of 10% ethylene glycol, 27% Ficoll, and 0.45 M sucrose) in cryotubes at a moderate cooling rate, and warmed at various rates. Survival was assessed according to the ability of the cells to develop into blastocysts and to develop to term. When embryos were vitrified at a 2,613 °C/min cooling rate and thawed by adding 1 mL of sucrose solution (0.3 M, 50 °C) at a warming rate of 18,467 °C/min, 58.1 ± 3.5% of the EFS10-vitrified embryos developed into blastocysts, and 50.0 ± 4.7% developed to term. These rates were similar to those of non-treated intact embryos. Using a conventional cryotube, we achieved developmental capabilities in one-cell rat embryos by rapid warming that were comparable to those of intact embryos, even using low concentrations (10%) of cell-permeating cryoprotectant and at low cooling rates.

Very high purity InP layer grown by liquid‐phase epitaxy using erbium gettering

1993 ◽  
Vol 73 (1) ◽  
pp. 468-470 ◽  
Author(s):  
Meng‐Chyi Wu ◽  
Cheng‐Ming Chiu
Keyword(s):  
Liquid Phase ◽  
Liquid Phase Epitaxy ◽  
High Purity ◽  
Very High

Diffusion In Insect Wing Muscle, The Most Active Tissue Known

1964 ◽  
Vol 41 (2) ◽  
pp. 229-256 ◽  
Author(s):  
TORKEL WEIS-FOGH
Keyword(s):  
Liquid Phase ◽  
Safety Factor ◽  
Metabolic Rates ◽  
High Concentration ◽  
Tracheal System ◽  
Insect Wing ◽  
Main Site ◽  
Normal Diffusion ◽  
Large Fibre ◽  
Very High

1. The tracheal system of insect wing muscle is so dense that between 10-1 and 10-3 of any cut area is occupied by air tubes. In most cases, air tube diffusion of O2 and CO2 through the muscle is therefore several thousand times quicker than diffusion in the liquid phase. 2. In large insects the primary tracheal supply must be strongly ventilated while diffusion is sufficient in the remaining part of the air tubes, even at the highest metabolic rates encountered in any insect. 3. The tracheoles represent the main site of exchange between the gaseous and the liquid phase while the tracheae are of little significance in this respect. The fibres cannot exceed about 20 µ in diameter unless the tracheoles indent the surface and become ‘internal’. 4. Muscular pumping of air and blood due to shortening is of little importance for the exchange of gases but of major importance for the supply with fuel for combustion. However, the large fibre diameters and the tidal nature of the pumping necessitates a very high concentration of fuel in the haemolymph. The high concentration of trehalose in insect blood is considered to be an essential adaptation to flapping flight. 5. The transport by diffusion of O2 and CO2 was followed in detail in a number of concrete examples in the gaseous as well as in the liquid phase. Within a safety factor of 2-3, the rate of transport was always found to be adequate. There is no reason to suggest other mechanisms than a simple, normal diffusion.

Analysis of Defects in Heavily-Doped MBE-GaAs

1982 ◽  
Vol 14 ◽  
Author(s):  
C.B. Carter ◽  
D.M. Desimone ◽  
H.T. Griem ◽  
C.E.C. Wood
Keyword(s):  
Liquid Phase ◽  
Molecular Beam ◽  
Type Material ◽  
Grown Layer ◽  
Defect Clusters ◽  
Complex Defect ◽  
Heavily Doped ◽  
Rich Material ◽  
P Type ◽  
Very High

ABSTRACTGaAs Has Been Grown By Molecular-Beam Epitaxy (MBE) With Large Concentrations (∼1018CM−2) Of Sn, Si, Ge, And Mn As Dopants. The Heavily-Doped N-Type Material Has Been Found To Contain Regions Of A Very High Dislocation Density. An Analysis Of The Less Complex Defect Areas Shows That The Dislocations Originate In The MBE-Grown Layer. These Observations And Others On More Complex Defect Clusters Are Compared With Recent Studies Of Defects In Material Grown By Liquid Phase Epitaxy (LPE). The More Heavily Doped P-Type Material Contains Discs Of Mn-Rich Material At The Surface Of The MBEgrown Epilayer. Both The Structure And Composition Of These Regions Have Been Examined.

scholarly journals Influence of mitochondria on phospholipid synthesis in preparations from rat liver

1973 ◽  
Vol 136 (3) ◽  
pp. 467-475 ◽  
Author(s):  
J. B. Roberts ◽  
F. L. Bygrave
Keyword(s):  
Rat Liver ◽  
Inhibitory Effect ◽  
Total Radioactivity ◽  
Phospholipid Synthesis ◽  
Low Concentrations ◽  
Absolute Requirement ◽  
Reconstituted System ◽  
Protein Incorporation ◽  
Very High ◽  
Cellular Phospholipid

1. The addition of mitochondria to an incubation system containing the soluble and microsomal fractions of rat liver enhances severalfold the incorporation of each of ethanolamine, phosphorylethanolamine and CDP-ethanolamine into phosphatidylethanolamine. 2. In the presence of microsomal, mitochondrial and soluble fractions, CDP-ethanolamine exhibits the greatest initial rate of incorporation (approx. 6nmol/h per mg of protein), being slightly faster than that of phosphorylethanolamine (approx. 5nmol/h per mg of protein). Incorporation of ethanolamine proceeds very slowly for the first 20min and only after 30min gives rates approaching those of the other two precursors. 3. By using a substrate ‘dilution’ technique it was shown that in the reconstituted system the affinity of each of the enzymes for their respective substrates is very high: 10μm for ethanolamine, 25μm for phosphorylethanolamine and 5μm for CDP-ethanolamine. 4. Isolation of the mitochondrial and microsomal fractions from the medium after incubation together with phosphorylethanolamine showed that about 70% of the total radioactivity was present in the microsomal fraction and about 30% in the mitochondria after only 20min. Similar experiments with ethanolamine as precursor revealed that after 20min only about 15% of the total radioactivity was present in the mitochondria but that after 40min about 30% was present in this fraction. 5. Heating and phospholipase treatment of mitochondria, but not freeze-thawing, eliminated the stimulatory effect of mitochondria on phospholipid synthesis. 6. The reconstituted system exhibits an absolute requirement for Mg2+(2mm gave maximal rates) and is inhibited by very low concentrations of Ca2+(100μm-Ca2+produced half-maximal inhibition with 3mm-Mg2+). Further addition of Mg2+overcame the Ca2+inhibition, suggesting that the inhibitory effect is readily reversible. 7. The concept that modification of the Mg2+/Ca2+ratio is a means of controlling the rate of cellular phospholipid synthesis is introduced.

Competitive reactions in the irradiation of anthracene + cyclohexane solutions

1959 ◽  
Vol 249 (1256) ◽  
pp. 51-64 ◽  
Keyword(s):  
Radiation Intensity ◽  
Quantitative Agreement ◽  
Radical Scavenger ◽  
Organic Systems ◽  
Low Concentrations ◽  
Radiation Induced ◽  
Experimental Values ◽  
Very High ◽  
Intensity Radiation ◽  
Good Agreement

Anthracene acts as a radical scavenger when present at low concentrations in irradiated hydrocarbons. A study has been made of the effect of radiation intensity and anthracene concentration on G( — A) , the number of anthracene molecules lost per 100 eV of energy absorbed. A theoretical calculation is made of the dependence of G( — A) on radiation intensity 1 and anthracene concentration ( A ), assuming that radiation-induced radicals (R.) are formed at random, and can either disappear by direct combination with one another, or with the anthracene to give RAR or RAAR bridges, or possibly some form of stabilized RA molecules. This theory is in good agreement with the experimental values of G( — A) measured at various low radiation intensities and anthracene concentrations. From the comparison estimates of the reactivity constants are derived. With very high intensity radiation quantitative agreement is less satisfactory, due to the non-steady conditions prevailing in a pulsed beam. The results obtained are compared with previous work on anthracene + hexane and iodine + cyclo hexane mixtures, in which the effect of radiation intensity was not investigated. The results reported here are of interest to the study of reaction kinetics in irradiated organic systems.

Operation of a nitrifying activated sludge airlift (NASA) reactor without biomass carrier

2000 ◽  
Vol 41 (4-5) ◽  
pp. 113-120 ◽  
Author(s):  
J.L. Campos ◽  
R. Mendez ◽  
J.M. Lema
Keyword(s):  
Activated Sludge ◽  
Air Flow ◽  
Small Diameter ◽  
Operation Time ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Total Biomass ◽  
Low Concentrations ◽  
The Mean ◽  
Very High

An ammonia loading rate of 4.1 kg N-NH4+/m3d was fully oxidized to nitrate using a nitrifying airlift without biomass carrier. The developed sludge, with a concentration of 12 gVSS/L and high density (100 gVSS/Lparticle), allowed particles to be retained with small diameter, having very low concentrations of solids in the effluent (5–10 mg VSS/L). The mean diameter of particles containing the majority of total biomass increased from 220 to 360 m during the operation time. The particle size analysis showed that the percentage of flocs with small diameter (1–3 m) is very high but the biomass content of these flocs is negligible with respect to the total biomass value. The oxygen transfer coefficient (KLa) was measured operating at different air flow rates, obtaining similar values during the overall operational period. The use of activated sludge without support gives high nitrifying rates with an easier fluidization and a lowercritical air flow rate than in a biofilm airlift reactor.

scholarly journals Delivering Minocycline into Brain Endothelial Cells with Liposome-Based Technology

2012 ◽  
Vol 32 (6) ◽  
pp. 983-988 ◽  
Author(s):  
Changhong Xing ◽  
Tatyana Levchenko ◽  
Shuzhen Guo ◽  
Monique Stins ◽  
Vladimir P Torchilin ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Tumor Necrosis ◽  
Proof Of Concept ◽  
Brain Endothelial Cells ◽  
Cerebral Endothelium ◽  
Low Concentrations ◽  
Tnf Α ◽  
Factor Α ◽  
Very High ◽  
Necrosis Factor

Minocycline has been proposed as a way to blunt neurovascular injury from matrix metalloproteinases (MMPs) during stroke. However, recent clinical trials suggest that high levels of minocycline may have deleterious side-effects. Here, we showed that very high minocycline concentrations damage endothelial cells via calpain/caspase pathways. To alleviate this potential cytotoxicity, we encapsulated minocycline in liposomes. Low concentrations of minocycline could not reduce tumor necrosis factor α (TNF α)-induced MMP-9 release from endothelial cells. But low concentrations of minocycline-loaded liposomes significantly reduced TNF α-induced MMP-9 release. This study provides proof-of-concept that liposomes may be used to deliver lower levels of minocycline for targeting MMPs in cerebral endothelium.

Effect of antifungals on itraconazole resistant Candida glabrata

2010 ◽  
Vol 5 (3) ◽  
pp. 318-323 ◽  
Author(s):  
Soňa Kucharíková ◽  
Patrick Dijck ◽  
Magdaléna Lisalová ◽  
Helena Bujdáková
Keyword(s):  
Amphotericin B ◽  
Biofilm Formation ◽  
Candida Glabrata ◽  
Antifungal Agents ◽  
Inhibitory Concentration ◽  
Clinical Isolates ◽  
Azole Resistance ◽  
Low Concentrations ◽  
Reduction Assay ◽  
Very High

AbstractIn the last decade, infections caused by Candida glabrata have become more serious, particularly due to its decreased susceptibility to azole derivatives and its ability to form biofilm. Here we studied the resistance profile of 42 C. glabrata clinical isolates to different azoles, amphotericin B and echinocandins. This work was also focused on the ability to form biofilm which plays a role in the development of antifungal resistance. The minimal inhibitory concentration testing to antifungal agents was performed according to the CLSI (Clinical and Laboratory Standards Institute) M27-A3 protocol. Quantification of biofilm was done by XTT reduction assay. All C. glabrata clinical isolates were resistant to itraconazole and sixteen also showed resistance to fluconazole. All isolates remained susceptible to voriconazole. Amphotericin B was efficient in a concentration range of 0.125–1 mg/L. The most effective antifungal agents were micafungin and caspofungin with the MIC100 values of ≤0.0313–0.125 mg/L. Low concentrations of these agents reduced biofilm formation as well. Our results show that resistance of different C. glabrata strains is azole specific and therefore a single azole resistance cannot be assumed to indicate general azole resistance. Echinocandins proved to have very high efficacy against clinical C. glabrata strains including those with ability to form biofilm.

scholarly journals Detection of endotoxins with the Limulus test in burned and unburned mice infected with different species of gramnegative bacteria

1975 ◽  
Vol 75 (1) ◽  
pp. 99-112 ◽  
Author(s):  
R. J. Jones ◽  
E. A. Roe ◽  
R. E. Dyster
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Low Concentrations ◽  
High Concentrations ◽  
Very High ◽  
Limulus Test

SUMMARYThe Limulus test detected endotoxins in the plasma of burned and unburned mice infected with different species of gram-negative bacteria. Individual strains of different species of gram-negative bacteria produced different amounts of endotoxin in the plasma of infected mice. Plasma from mice given lethal infections showed very high concentrations of endotoxin. Low concentrations of endotoxin in the plasma were tolerated by mice but high concentrations were invariably fatal. A polyvalent pseudomonas vaccine reduced endotoxin in the plasma of mice given lethal infections of Pseudomonas aeruginosa.

Sign in / Sign up

Export Citation Format

Share Document