Characterization of a high strain composite material

L'Garde has designed and developed a high-strain composite material consisting of car- bon FIbers embedded in a silicone matrix. The behavior of this material is significantly different from standard composites and the paper presents special test methods to measure the properties of this material. It is found that rule of mixtures estimates are quite accurate for the longitudinal moduli in tension and bending, but less accurate for compression. The Poisson's ratio prediction is also not accurate. Regarding the strength of the composite, it is found that conservative predictions of tensile and compressive strengths can be obtained respectively from the Weibull distribution of the strength of a single fiber combined with a simple bundle theory, and the elastic fiber microbuckling stress

Long-distance migration and venting of methane from the base of the hydrate stability zone

\ua9 2023, The Author(s).Marine methane hydrate is an ice-like substance that is stable in sediment around marine continental margins where water depths are greater than ~450–700 m. The release of methane due to melting of hydrates is considered to be a mechanism for past global carbon-cycle perturbations and could exacerbate ongoing anthropogenic climate change. Increases in bottom-water temperature at the landward limit of marine hydrate around continental margins, where vulnerable hydrate exists at or below the seabed, cause methane to vent into the ocean. However, this setting represents only ~3.5% of the global hydrate reservoir. The potential for methane from hydrate in deeper water to reach the atmosphere was considered negligible. Here we use three-dimensional (3D) seismic imagery to show that, on the Mauritanian margin, methane migrated at least 40 km below the base of the hydrate stability zone and vented through 23 pockmarks at the shelf break, probably during warmer Quaternary interglacials. We demonstrate that, under suitable circumstances, some of the 96.5% of methane bound in deeper water distal hydrates can reach the seafloor and vent into the ocean beyond the landward limit of marine hydrate. This reservoir should therefore be considered for estimating climate change-induced methane release during a warming world

Estimulación de la rama izquierda a través de acceso venoso derecho

Varón de 51 años que ingresó por síncope, objetivándose en la monitorización un bloqueo auriculoventricular completo. Dado que el paciente presentaba disfunción sistólica ligera del ventrículo izquierdo, se decidió implantar un marcapasos definitivo con estimulación fisiológica de la rama izquierda del haz de His. Tras punciones axilar y subclavia izquierdas fallidas se realizó venografía, que mostró oclusión del sistema venoso izquierdo con abundante circulación colateral (fig. 1 A). Se canalizó el acceso venoso por punción subclavia derecha, logrando implantar el electrodo ventricular en la rama izquierda con ayuda de una vaina fija modificada de forma manual (modelo C315HIS, Medtronic, Minneapolis). No se objetivaron complicaciones en la radiografía postimplante (fig. 1 B). El QRS basal presentaba 142 ms, quedando finalmente un QRS estimulado de 98 ms (fig. 2 A y B). Los parámetros 24 horas tras el implante fueron correctos..

Depolarization-repolarization synchrony after right ventricular and left bundle branch area pacing

Introduction: Left bundle branch area pacing (LBBAP) has been recently proposed to overcome the limitations associated with right ventricular pacing (RVP) and has been suggested as a new physiological pacing form with high feasibility and safety. A greater difference between QRS complex and T-wave angle directions has been proposed as a marker of abnormal electrical activity in several patient populations, but a comparison between these two pacing modalities has never been performed. The total cosine R to T (TCRT) is an ECG descriptor that accounts for depolarization-repolarization synchrony by measuring the difference between their directions. The purpose of this study was to compare TCRT in patients referred for RVP and LBBAP pacing as anti-bradycardia therapy. Methods: ECG recordings from 134 patients (82 LBBAP, 52 RVP) were classified into two groups, narrow QRS and wide QRS, depending on the patient’s QRS duration prior to implantation. In the post-implantation state, the TCRT index was calculated from a median beat calculated for each patient. Singular value decomposition was applied to the median beat in the eight independent ECG leads (I, II, V1, V2, V3, V4, V5, V6). The QRS complex and T wave loops in a three-dimensional space were determined from the first three components of the decomposition. TCRT was computed as the average of the cosines of the angles between the QRS complex directions and the maximum T wave direction. More positive values corresponded to more synchronized depolarization and repolarization processes while more negative values indicated larger differences in the orientation of the QRS and T wave loops and, therefore, greater dyssynchronization. Results: showed that TCRT took negative values for both techniques, RVP and LBBAP, and both groups, narrow and wide QRS, indicating that pacing generated dyssynchronization between ventricular depolarization and repolarization. Nevertheless, TCRT values for both groups were significantly more negative (p<0.01) for RVP than for LBBAP. We hypothesize that cardiac memory induced by pacing could account for these negative TCRT values. In any case, LBBAP did not increase the difference in the QRS complex and T wave loop orientations as much as RVP. Conclusion: LBBAP induces less dyssynchrony than RVP in the depolarization-repolarization process

Swarm hybrid optimization for a piecewise model fitting applied to a glucose model

[EN] Purpose ¿ The purpose of this paper is to study insulin pump therapy and accurate monitoring of glucose levels in diabetic patients, which are current research trends in diabetology. Both problems have a wide margin for improvement and promising applications in the control of parameters and levels involved. Design/methodology/approach ¿ The authors have registered data for the levels of glucose in diabetic patients throughout a day with a temporal resolution of 5 minutes, the amount and time of insulin administered and time of ingestion. The estimated quantity of carbohydrates is also monitored. A mathematical model for Type 1 patients was fitted piecewise to these data and the evolution of the parameters was analyzed. Findings ¿ They have found that the parameters for the model change abruptly throughout a day for the same patient, but this set of parameters account with precision for the evolution of the glucose levels in the test patients. This fitting technique could be used to personalize treatments for specific patients and predict the glucose-level variations in terms of hours or even shorter periods of time. This way more effective insulin pump therapies could be developed. Originality/value ¿ The proposed model could allow for the development of improved schedules on insulin pump therapiesAcedo Rodríguez, L.; Botella, M.; Cortés, J.; Hidalgo, J.; Maqueda, E.; Villanueva Micó, RJ. (2018). Swarm hybrid optimization for a piecewise model fitting applied to a glucose model. Journal of Systems and Information Technology. 20(4):9618-9627. https://doi.org/10.1108/JSIT-10-2017-0103S9618962720

His-Bundle Pacing in a Patient With Tricuspid and Mitral Prosthetic Valves Without Suitable Coronary Veins for Lead Placement

Atrioventricular block in patients with a prosthetic tricuspid valve and a pacemaker with a dysfunctional epicardial lead is not uncommon. In such instances, coronary sinus lead placement is the preferred option, but it has a failure rate of 10%-15%. An atrial transseptal left ventricular lead placement has been proposed as an alternative, but this approach is not feasible in patients with a prosthetic mitral valve. This analysis represents the first reported case of His-bundle pacing from the atria in a patient with prosthetic tricuspid and mitral valves, with no suitable coronary veins for lead placement. © 2021 The Author

Flash sintering of highly insulating nanostructured phase-pure BiFeO3

We show that BiFeO, that is electrically homogeneous, is a good insulator, and has a low dielectric constant (the properties desired in its applications), can be produced by flash sintering, which is nominally difficult to achieve by conventional and spark plasma sintering processes. The flash-sintered specimens had a uniform microstructure with a nanometric grain size of ~20 nm.Ministerio de Economía y Competitividad CTQ2014-52763-C2-1-RJunta de Andalucía TEP- 7858Office of Naval Research (USA) N00014-15-1-250

Analysis of the Promoters Involved in Enterocin AS-48 Expression

The enterocin AS-48 is the best characterized antibacterial circular protein in prokaryotes. It is a hydrophobic and cationic bacteriocin, which is ribosomally synthesized by enterococcal cells and post-translationally cyclized by a head-to-tail peptide bond. The production of and immunity towards AS-48 depend upon the coordinated expression of ten genes organized in two operons, as-48ABC (where genes encoding enzymes with processing, secretion, and immunity functions are adjacent to the structural as-48A gene) and as-48C1DD1EFGH. The current study describes the identification of the promoters involved in AS-48 expression. Seven putative promoters have been here amplified, and separately inserted into the promoter-probe vector pTLR1, to create transcriptional fusions with the mCherry gene used as a reporter. The activity of these promoter regions was assessed measuring the expression of the fluorescent mCherry protein using the constitutive pneumococcal promoter PX as a reference. Our results revealed that only three promoters PA, P2(2) and PD1 were recognized in Enterococcus faecalis, Lactococcus lactis and Escherichia coli, in the conditions tested. The maximal fluorescence was obtained with PX in all the strains, followed by the P2(2) promoter, which level of fluorescence was 2-fold compared to PA and 4-fold compared to PD1. Analysis of putative factors influencing the promoter activity in single and double transformants in E. faecalis JH2-2 demonstrated that, in general, a better expression was achieved in presence of pAM401-81. In addition, the P2(2) promoter could be regulated in a negative fashion by genes existing in the native pMB-2 plasmid other than those of the as-48 cluster, while the pH seems to affect differently the as-48 promoter expression.This work was supported in part by the Ministerio de Ciencia e Innovación project BIO2008-01708, the Plan Propio from the University of Granada (Spain) and by the Research Plan Group (BIO 160)