Clamp Analysis Research Articles

Miocene (Burdigalian) coastal lowland vegetation and palaeoclimate based on a palaeoenvironmental reconstruction of the Els Cardscolers site, Majorca, Spain

The early Miocene (Burdigalian) macroflora of the Els Cardscolers site (Majorca Island, Balearic Islands province, Spain) is studied here from a palaeoecological and taxonomical perspective. The study shows the presence of a palaeotropical flora with thermophilic and hygrophilic elements characteristic of a coastal wetland environment, formed by monocotyledons, Lygodium gaudinii, palms (Sabalites sp.), a predominance of shrubs with Myrica lignitum and the presence of accessory elements such as Berberis kymeana, Engelhardia orsbergensis, Ziziphus paradisiaca, Sapotacites minor and Myrica longifolia. Arboreal taxa like Lauraceae or Fagaceae and some Fabaceae species were also present. The temperature values obtained by CLAMP analysis are as follows: MAT: 17.6–19.9 °C, WMMT: 24.3–27.07 °C, and CMMT: 10.4–14.2 °C. These findings suggest a warm climate with little temperature seasonality. Precipitation values (e.g., GSP, MMGSP, Three_WET, and Three_DRY) suggest the absence of a summer-dry regime although a clear contrast in precipitation is inferred. The inferred climate is similar to that of other coeval regions of Southern Europe, although it stands out for its high values of CMMT. It is similar to the climate of the island of Evia in Greece. From a floristic point of view, the Els Cardscolers flora is similar to the Burdigalian site of Cristo Rei (Portugal), and a clear relationship with the floral complex of Ipolytarnóc-Luzern (Hungary) also can be inferred.

1515-P: Effect of Aging on Insulin Clearance in Mice

Aging is commonly linked with hyperinsulinemia and insulin resistance. Age-related hyperinsulinemia results from increased insulin secretion and/or decreased insulin clearance as compensatory mechanisms to peripheral insulin resistance. Several studies have reported reduced β-cell function in elderly rodents and humans. Earlier reports on decreased insulin clearance due to aging suggest that hyperinsulinemia in elderly could be explained predominantly by a reduction in insulin clearance. Hence, we aim to better understand the role of aging on insulin clearance following fat infusion. To investigate the aging effect, 3 months and 10-14 months old C57BL6 mice were infused with ethylpalmitate for 48h (hydrolyzed to palmitate and ethanol in plasma), to achieve elevated circulating FFA in a non-toxic manner. Mice were then subjected to hyperglycemic clamp, and during the clamp plasma C-peptide and insulin were measured to evaluate insulin clearance. Glucose infusion rate (GINF), insulin sensitivity index (SI) and disposition index (DI) were also assessed during clamp analysis. GINF is a measure of glucose tolerance whereas DI evaluates β-cell function. Whereas insulin secretion did not increase, insulin clearance was reduced in the aging mice, as indicated by the lower C-peptide/insulin molar ratio, observed during hyperglycemic clamp. No significant changes were observed in GINF between old and young mice; however, SI and DI were lower in elderly group. These results collectively suggest that with advancing age, β-cells may lose their ability to maintain a higher insulin secretion and that reduced hepatic insulin clearance plays a more dominant role to compensate for age-related decline in insulin sensitivity. Disclosure S.Rahman: None. S.Zaidi: Other Relationship; BullFrog AI. H.T.Muturi: None. S.M.Najjar: None. A.Giacca: None.

The constant/variable kinematics adjustment of the crosshead and the mold’s stability management in injection molding

During the clamping process in an injection-molding machine, the mold’s movement is directly driven by the velocity of the crosshead. The form of the adjustment on the crosshead’s kinematics can influence the final dynamics of the mold, which can contribute to the stability of the clamping duration further. This article is aimed at investigating the kinematics analysis and the stability management strategy of the mold in the early design stage for the clamping mechanism. The two different velocity-controlled forms of the crosshead, constant and variable kinematics adjustments, are applied and compared in the clamping analysis. Three factors of the crosshead, the maximum velocity, the acceleration/deceleration stage adjustment, and the multi acceleration/deceleration process, are validated for the stability control of the mold’s motion in the injection molding process. The results show an extra “fast” process is detected in the constant condition when compared to the variable crosshead’s kinematics adjustment. Furthermore, by the reasonable adjustment of the maximum velocity and two special positions of the crosshead during the acceleration and deceleration stages, the maximum acceleration fluctuation of the mold is decreased by more than 50%, allowing the mold to move more steadily.

Tyrosine-protein kinase Src regulates Kv1.5 channel activity and membrane expression through interaction with the N-terminus of the channel

Kv1.5 is a voltage-gated potassium channel that generates the ultra-rapid delayed rectifier potassium current (IKur) important in the repolarization of the atrial action potential. Malfunction of the Kv1.5 channel often results in atrial fibrillation (AFib). A reduction in Kv1.5 current (IKv1.5) occurs upon activation of the endogenous tyrosine-protein kinase Src. The Src SH3 domain binds to proline-rich motifs located within the N-terminus of Kv1.5. Disruption of these binding motifs has been involved in the development of familial AFib. The mechanism underlying the reduction of IKv1.5 upon Src activation has not yet been established and the relationship between Kv1.5 and Src is poorly understood. Therefore, the present study aims to further elucidate the mechanism behind IKv1.5 reduction. The hypothesis that Src regulates Kv1.5 activity by altering the density of mature membrane-localized channels was tested using whole-cell voltage clamp and Western blot analysis. We demonstrate that Src tonically inhibits Kv1.5 activity and decreases the density of mature membrane-localized channels. Kv1.5 channels possessing mutations within the Src binding motifs were also investigated and it was determined that each binding motif contributes to the Kv1.5-Src relationship, however, the binding of Src to an individual motif is sufficiently effective. Our findings indicate that Src regulates Kv1.5 through an interaction with the N-terminal binding motifs and suggests that the inhibition of forward trafficking may be involved in the underlying mechanism. (Supported by the Heart and Stroke foundation of Canada and The Canadian Institutes of Health Research).

Early Miocene climate estimations in Patagonia: The case of Pico Quemado, Ñirihuau Formation (Lower-Middle Miocene)

The climate during the early Neogene in Patagonia is characterized by the increase of the average temperatures until the mid-Miocene Climatic Optimum. However, the terrestrial paleoclimate of southern South America during this period is unclear. Therefore, a physiognomic analysis on the Pico Quemado (Ñirihuau Formation, lower-middle Miocene) megaflora was realized. Three types of analyses were performed: 1) Leaf Margin Analysis (LMA); 2) Leaf Area Analysis (LAA); and 3) a CLAMP analysis (Climate Leaf Analysis Multivariate Program) with two different dataset. The LMA and CLAMP predicted an estimated a Mean Annual Temperature of 10.4 ± 2.1 °C, 8.5 ± 2.1 °C and 7.2 ± 1.4 respectively. The estimations of Mean Annual Precipitation were of 123.7 ± 21.2 cm. Through the CCA, other parameters were estimated, i. e. Cold Mean Month Temperature (−3.3 ± 3.8 °C, 1.6 ± 1.6 °C); Warm Mean Month Temperature (17.4 ± 3.3 °C; 14.1 ± 1.2 °C); Mean Growing Season Precipitation (121.9 ± 42.6 cm; 78.1 ± 42.6 cm); Precipitation of the Three Consecutive Wettest Months (116.2 ± 15.3 cm; 88.5 ± 15.3 cm); and Precipitation of the Three Consecutive Driest Months (40.2 ± 19.8 cm; 54.1 ± 19.8 cm). From these results, the Pico Quemado megaflora can be characterized as having a cool temperate climate, with moderate precipitations and the development of bi-seasonality. The obtained estimations are concordant with previous morphological studies in Pico Quemado, which had proposed the same climate conditions. However, these results are inconsistent compared to other studies of early Neogene Southern Hemisphere that suggest that the climate could be warmer. This difference might be due to the few studies of climatic estimations during the early Neogene in Patagonia, precluding detailed comparisons. In conclusion, Pico Quemado paleoflora exhibits unique climatic conditions, and also floral compositions, as suggested in previous works and here corroborated. The study realized constitutes the first climatic estimations for an Argentinean megaflora developed during the Neogene.

Assessment of Compound Effects on Electrophysiology of hiPSC-Derived Ventricular Cardiomyocytes Using Patch Clamp and Multielectrode Array (MEA) Analysis

Assessment of Compound Effects on Electrophysiology of hiPSC-Derived Ventricular Cardiomyocytes Using Patch Clamp and Multielectrode Array (MEA) Analysis

Glucose Homeostatic Law: Insulin Clearance Predicts the Progression of Glucose Intolerance in Humans.

Homeostatic control of blood glucose is regulated by a complex feedback loop between glucose and insulin, of which failure leads to diabetes mellitus. However, physiological and pathological nature of the feedback loop is not fully understood. We made a mathematical model of the feedback loop between glucose and insulin using time course of blood glucose and insulin during consecutive hyperglycemic and hyperinsulinemic-euglycemic clamps in 113 subjects with variety of glucose tolerance including normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and type 2 diabetes mellitus (T2DM). We analyzed the correlation of the parameters in the model with the progression of glucose intolerance and the conserved relationship between parameters. The model parameters of insulin sensitivity and insulin secretion significantly declined from NGT to IGT, and from IGT to T2DM, respectively, consistent with previous clinical observations. Importantly, insulin clearance, an insulin degradation rate, significantly declined from NGT, IGT to T2DM along the progression of glucose intolerance in the mathematical model. Insulin clearance was positively correlated with a product of insulin sensitivity and secretion assessed by the clamp analysis or determined with the mathematical model. Insulin clearance was correlated negatively with postprandial glucose at 2h after oral glucose tolerance test. We also inferred a square-law between the rate constant of insulin clearance and a product of rate constants of insulin sensitivity and secretion in the model, which is also conserved among NGT, IGT and T2DM subjects. Insulin clearance shows a conserved relationship with the capacity of glucose disposal among the NGT, IGT and T2DM subjects. The decrease of insulin clearance predicts the progression of glucose intolerance.

Growing conditions of the Ust’-Emuneret flora and the Santonian-Campanian climate of Chukotka

New data on climatic conditions of the Ust’-Emuneret flora growth in the Enmyvaam River basin, Okhotsk-Chukotka volcanic belt, are reported. A great diversity of woody dicot leaves in the studied flora permits for the first time for this region the reconstruction of quantitative paleoclimatic parameters using the CLAMP analysis. On the basis of the available results, the Santonian-Campanian climate of the northern Okhotsk-Chukotka volcanic belt and the adjacent Anadyr-Koryak region is analyzed.

Design of Hydraulic Telescopic Grouted Clamp Device and Analysis of Its Closing Collision

ABSTRACT Zhang, B.; Wang, Z.; Wang, T., and Sun, L., 2015. Design of hydraulic telescopic grouted clamp device and analysis of its closing collision. The strengthening structure for the underwater jacket of offshore platform has been studied, which is used to reinforce the jacket's fragile points and damaged parts. A technical support for the strengthening area of the civil offshore platform is also provided. Besides, the overall plan is put forward on the structure of the hydraulic telescopic grouted clamp, including the general mechanical structure and the hydraulic control system. The general mechanical structure of the clamp is designed to achieve the automatically closing and locking process of the clamp and especially to resolve the self-locking problem. Moreover, the maximum impact force of the clamp can be reduced by the speed optimization design of the hydraulic cylinders and effectively improve the clamp structural strength.

Calcium current inactivation rather than pool depletion explains reduced exocytotic rate with prolonged stimulation in insulin-secreting INS-1 832/13 cells.

Impairment in beta-cell exocytosis is associated with reduced insulin secretion and diabetes. Here we aimed to investigate the dynamics of Ca2+-dependent insulin exocytosis with respect to pool depletion and Ca2+-current inactivation. We studied exocytosis, measured as increase in membrane capacitance (ΔCm), as a function of calcium entry (Q) in insulin secreting INS-1 832/13 cells using patch clamp and mixed-effects statistical analysis. The observed linear relationship between ΔCm and Q suggests that Ca2+-channel inactivation rather than granule pool restrictions is responsible for the decline in exocytosis observed at longer depolarizations. INS-1 832/13 cells possess an immediately releasable pool (IRP) of ∼10 granules and most exocytosis of granules occurs from a large pool. The latter is attenuated by the calcium-buffer EGTA, while IRP is unaffected. These findings suggest that most insulin release occurs away from Ca2+-channels, and that pool depletion plays a minor role in the decline of exocytosis upon prolonged stimulation.

Early Senonian climate reconstruction for southwestern Siberia on the basis of paleobotanical data

On the basis of study of fossil plants, the climate in southwestern Siberia in the Early Senonian was reconstructed to be warm temperate humid with the mean annual temperature of about 13°C. The CLAMP analysis (Climate Leaf Analysis Multivariate Program) was applied for the first time to Cretaceous floras of Western Siberia. The comparison results of climatic variables estimated show that the climate in Western Siberia in the Early Senonian was more humid and warmer than in Northeast Asia.

Automatic Programming Based on the Feature of the Parts

The structure of machining workpiece is more and more complex, from the perspective of CNC machining, contains a lot of processing features generally. Machining feature plays an important role for production process for CNC machining programming, CNC code, as well as the analysis of clamping. Feature programming is one of the development trend of automatic CNC programming. This improve the efficiency of programming greatly.

Welding distortion control of automobile engine stator by finite element method

In this paper, a thermal elastic-plastic finite element method (FEM) is used to simulate the plasma welding process in order to predict the welding distortion of automobile stator iron core. Six spatial symmetrical welding torches are adopted in the welding process so as to make the iron core rings welded firmly and the distortion symmetric. The effect of rigid clamp on actual welding process is replaced by the contact function between rigid body and deformation element in the MSC software, MARC. The welding process restrained by clamp and deformation analysis after the removal of clamp was successfully simulated. The predictions show good agreement with the test results when the rigid clamps are taken into account in the welding simulation, which satisfies the design requirement for manufacture.

Chloramine-T effect on sodium conductance of neuroblastoma cells as studied by whole-cell clamp and single-channel analysis.

Patch-clamp experiments were done on sodium channels of neuroblastoma cells (N1E-115) in the presence of tetraethylammonium ions to block potassium channels. In Ringer solution whole-cell records revealed a diphasic INa inactivation with the fast (tau 0) component. being clearly larger than the slow (tau 1 approximately 3 tau 0) component. In single-channel studies on inside-out patches the mean open time, to, turned out to be only a fraction of tau 0 and almost independent of membrane potential. After external application of chloramine-T INa inactivation of whole cells was delayed with both tau 0 and tau 1 increased, and incomplete, i.e. a persistent current component emerged. The latter was maximal at a more positive membrane potential than the peak current. Also, after chloramine-T treatment the peak INa increased, particularly at weak depolarizations. In inside-out patches the equally effective internal application of chloramine-T led to bursting channel openings with mean burst times (tb) approximately 6 ms, and gap times (tg) approximately 20 ms, where gap is defined as a closure of greater than or equal to 1.5 ms. Within the bursts to was approximately 2 ms, again clearly shorter than tau 0; the mean close time, tc was approximately 0.5 ms. The single-channel conductance was approximately 13 pS and unaffected by chloramine-T. Diphasic INa inactivation and the fact that to less than tau 0 led to an extension of the model of Aldrich and Stevens [J Neurosci 7:418-431 (1987)], in which overall kinetics is determined by the openings rather than closures of the sodium channels.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of clamps with time dependent voltages in the squid axon using a kinetic transport model

A sequential kinetic, open system model for potassium currents in squid axon is used to develop analytical expressions for current fluxes during time dependent voltage clamp experiments. These analytical solutions suggest a technique for extracting rate constant data directly from the current voltage curves generated during such clamps. The analytical solutions involve a simple decay scheme which provides a simple explanation for hysteresis effects observed with such clamps. In addition, the solutions predict a minimal time dependence for the hyperbolic voltage clamp, i.e., the observed current fluxes during a hyperbolic voltage clamp will tend to be independent of the rate of decay. The use of this clamp for the rapid separation of sodium and potassium currents is discussed.