ABSTRACT
We explore an analogue of optical frequency combs in driven nonlinear phononic systems, and present a mechanism for generating phononic frequency combs through nonlinear resonances. In the underlying process, a set of phonon modes is simultaneously excited by the external driving which yields frequency combs with an array of discrete and equidistant spectral lines of each nonlinearly excited phonon mode. Frequency combs through nonlinear resonance of different orders are investigated, and in particular the possibility of correlation tailoring in higher-order cases is revealed. We suggest that our results can be applied in various nonlinear acoustic processes, such as phonon harvesting, and can also be generalized to other nonlinear systems.
ABSTRACT
We demonstrate that the electronic property of a mesoscopic ring can be alternatively tuned between metallic and insulative states by changing the Fermi level. The one-dimensional mesoscopic ring is constructed based on random n-mer model and threaded by magnetic flux. Multiple localization-delocalization transitions of electrons have been found. When the Fermi level approaches the resonant energy, persistent current approaches the behavior of free electrons regardless of the disorder, corresponding to the metallic feature. Away from the resonant state, the current is dramatically diminished, indicating an insulative feature. We suggest our results have potential application in designing quantum switch devices.
ABSTRACT
AIM: To study the method of using BRL conditioned medium in ES cells culture. METHODS: ES cells were cultured in BRL conditioned medium, MEF feeder layer, and BRL conditioned medium plus MEF feeder layer respectively. Both the numbers of ES cells and embryonic bodies and the differentiated cells around the ES cell colonies at certain stages were studied to find the differences of growing speed of ES cells in three culture mediums. RESULTS: On promoting the growth and maintaining the undifferentiated state of ES cells at the early stage after recovery, the effects of BRL conditioned medium were less than those of MEF feeder layer and those of BRL conditioned medium plus MEF feeder layer (P < 0.01), and there was no difference between MEF feeder layer and BRL conditioned medium plus MEF feeder layer (P > 0.05). CONCLUSION: ES cells should be cultivated on MEF feeder layer or in BRL conditioned medium plus MEF feeder layer at the early stage after recovering.
Subject(s)
Cell Culture Techniques/methods , Culture Media, Conditioned , Embryonic Stem Cells/cytology , Animals , Cells, Cultured , Hepatocytes , Mice , Mice, Inbred BALB C , Rats , Rats, Inbred BUFABSTRACT
1. The reported incidence of myocardial contusion after blunt chest trauma varies from 16 to 76%. Of these patients, about 6% present a severe, life threatening contusion. We used an isolated heart preparation to examine the effect of lignocaine on myocardial performance after contusion. 2. Thirty hearts obtained from male New Zealand rabbits were perfused at constant flow according to the Langendorff technique and were divided into four groups. The following parameters were measured at frequent intervals for 60 min: mean coronary perfusion pressure (CPP), left ventricular diastolic pressure (LVDP), developed pressure (DP), dP/dtmax, dP/dtmin. 3. Group 1 (n = 6) served as control, group 2 (n = 7) received lignocaine for 20 min (15 microM for the first 10 min and 30 microM for the following 10 min), group 3 (n = 9) had a contusion leading to a 30-50% decrease in dP/dtmax and group 4 (n = 8) had the contusion and the lignocaine infusion was started 10 min after the contusion and stopped after 30 min. Lignocaine concentration was measured in the effluent. 4. Lignocaine alone moderately decreased contractility in group 2. In group 3, after contusion, DP, dP/ dtmax, and dP/dtmin were markedly decreased during the 60 min recording period. In group 4, lignocaine infusion rapidly restored contractility. DP, dP/dtmax and dP/dtmin returned towards their basal values. This improvement of contractility remained stable, even after lignocaine infusion was discontinued. 5. In our rabbit isolated heart preparation, lignocaine at a low therapeutic concentration was able to restore contractility after contusion. These results need to be confirmed by other studies but this may lead to promising therapeutic intervention.
Subject(s)
Anti-Arrhythmia Agents/pharmacology , Contusions/drug therapy , Heart/drug effects , Lidocaine/pharmacology , Wounds, Nonpenetrating/complications , Analysis of Variance , Animals , Contusions/etiology , Male , Myocardial Contraction/drug effects , RabbitsABSTRACT
Binding parameters of R(+)- and S(-)-bupivacaine were determined for human serum proteins, human alpha-1-acid glycoprotein (AAG) and human serum albumin (HSA), using ultrafiltration. Binding parameters were estimated according to the Scatchard model of the law of mass action using nonlinear regression. A sigmoid (cooperativity) term was added when needed. Both enantiomers exhibited a two site binding profile for human serum and for a solution containing AAG and HSA at physiological concentrations. At concentrations lower than 40 microM (concentrations encountered in clinical situations), the low capacity, high affinity apparent site was predominant and S(-)-bupivacaine exhibited a higher free fraction than R(+)-bupivacaine. At concentrations higher than 60 microM, the opposite situation was observed and the S(-) enantiomer showed much higher binding to AAG than the R(+) enantiomer. Two cooperativity phenomena occurred. Negative cooperativity was observed when AAG and HSA were combined in the same solution. S(-) and R(+) enantiomers exhibited different behavior toward purified AAG and HSA due in part to complex allosteric cooperativity (positive or negative depending on the ligand/protein ratio). In conclusion, we observed stereoselective binding of bupivacaine to AAG and HSA. Moreover, cooperativity occurred, and the behavior of the two enantiomers showed marked differences in this respect.
Subject(s)
Anesthetics, Local/metabolism , Blood Proteins/metabolism , Bupivacaine/metabolism , Orosomucoid/metabolism , Serum Albumin/metabolism , Adult , Anesthetics, Local/blood , Buffers , Humans , Kinetics , Male , Middle Aged , Orosomucoid/isolation & purification , Protein Binding , Serum Albumin/isolation & purification , Solutions , StereoisomerismABSTRACT
Two-dimensional echocardiography was used to guide and locate the balloon of Swan-Ganz catheter during catheterization in 43 patients. The echoes of balloon appeared as a series of strong light spots, with a rate of detection of 100%. Under monitoring of two-dimensional echocardiography, the site of balloon and its moving route could be determined. The coincidence of echographic findings and X-ray findings showed that it can be used instead of X-ray monitoring to lessen irradiation during catheterization. The depth of catheter inserted was measured. The differential points between the echoes of balloon and tubing, the terminology of the balloon site in echocardiography and fluoroscopy, its clinical value and limitation are discussed.
Subject(s)
Catheterization, Swan-Ganz/methods , Echocardiography , Adolescent , Adult , Child , Ductus Arteriosus, Patent/diagnosis , Female , Heart Septal Defects, Atrial/diagnosis , Heart Septal Defects, Ventricular/diagnosis , Humans , Male , Middle AgedSubject(s)
Cardiac Catheterization , Catheterization, Swan-Ganz , Ductus Arteriosus, Patent/diagnosis , Echocardiography/methods , Heart Septal Defects/diagnosis , Adolescent , Adult , Child , Female , Humans , Hydrogen Peroxide/administration & dosage , Injections, Intravenous/methods , Male , Middle Aged , Pulmonary VeinsABSTRACT
The selenium (Se) level in barley and maize from 43 communes of Qidong county, a high risk area of liver cancer in China, were assayed. An inverse correlation between the Se level and the liver cancer incidence was observed. An inverse correlation was also observed between the blood Se level and liver cancer incidence of the local residents. When selenite solution was sprayed on the crops during their preflowering, the content of Se in barley and maize was increased by 6 fold over the control. It is suggested that the increase of blood Se level of the residents who live in the low-Se areas by this method be useful in the prevention of liver cancer.
