Understanding the functional limits of single use components through pressure testing

Transferring fluid from one container to another is a very common bioprocessing operation. A variety of different components have been created for the purpose of fluid transfer, including bag ports, tubing, aseptic connectors, barbed fittings, tubing retainers, etc. In order to provide high quality, highly reliable single use assemblies, it is important to test the functional limits of fluid transfer components. Thermo Fisher has designed a versatile system to test the pressure limits of components. Please click Additional Files below to see the full abstract

Relative intensity influences the degree of correspondence of jump squats and push jerks to countermovement jumps

The aim of this study was to determine the mechanical similarity between push jerk (PJ) and jump squat (JS) to countermovement jump (CMJ) and further understand the effect increasing external load may have on this relationship. Eight physically trained males (age 22 ± 3; height 176 ± 7 kg; weight 83 ± 8 kg) performed an unloaded CMJ followed by JS under a range of loads (10%, 25%, 35% and 50% 1RM back squat) and PJ (30%, 50%, 65% and 75% 1RM push jerk). A portable force platform and high speed camera both collecting at 250 Hz were used to establish joint moments and impulse during the propulsive phase of the movements. A standard inverse dynamics model was used to determine joint moment and impulse at the hip, knee and ankle. Significant correlations (p<0.05) were shown between CMJ knee joint moment and JS knee joint moment at 25% load and PJ knee joint moment at 30% and 50% load. Significant correlations were also observed between CMJ knee joint impulse and JS knee joint impulse at 10% load and PJ knee joint moment at 30% and 65% load. Significant correlation was also observed between CMJ hip joint impulse and PJ hip joint impulse at 30% load. No significant joint x load interaction was shown as load increased for either PJ or JS. Results from the study suggest partial correspondence between PJ and JS to CMJ, where a greater mechanical similarity was observed between the PJ and CMJ. This interaction is load and joint dependent where lower relative loads showed greatest mechanical similarity. Therefore utilising lower relative loads when programming may provide a greater transfer of training effect

Peak power output in the bench pull is maximised after 4 weeks of specific power training

Maximal power production has been shown to be a differentiating factor between playing levels in many sports and is thus a focus of many strength and conditioning programmes. We sought to evaluate the duration for which a strategy of training with the optimal load (that maximises power output) will be effective in producing improvements in power output in the bench pull. The optimal load that produced the maximum power output in the bench pull was determined for twenty-one male university athletes who were randomly assigned to a group that trained with their optimal load or a load 10% of their one repetition maximum below the optimal load. Both groups completed two sessions per week for 4 weeks, after which their power output capabilities were reassessed. They then trained for a further 3 weeks with a load that was modified to reflect changes in their optimal load. The cohort as a whole had improved their peak power output by 4.6% (p = 0.002, d = 0.290) after 4 weeks of training, but experienced no further increase after another 3 weeks of training. There were no significant differences in the response to training between the two groups. This study suggests that improvements in power output can be realised within a few weeks when training with the optimal load, but training in such a way for a longer duration may be ineffective. Strength and conditioning coaches should consider periodizing power training to maximise gains in power output capabilities

Hip and knee joint loading during vertical jumping and push jerking

BACKGROUND: The internal joint contact forces experienced at the lower limb have been frequently studied in activities of daily living and rehabilitation activities. In contrast, the forces experienced during more dynamic activities are not well understood, and those studies that do exist suggest very high degrees of joint loading. METHODS: In this study a biomechanical model of the right lower limb was used to calculate the internal joint forces experienced by the lower limb during vertical jumping, landing and push jerking (an explosive exercise derived from the sport of Olympic weightlifting), with a particular emphasis on the forces experienced by the knee. FINDINGS: The knee experienced mean peak loadings of 2.4-4.6×body weight at the patellofemoral joint, 6.9-9.0×body weight at the tibiofemoral joint, 0.3-1.4×body weight anterior tibial shear and 1.0-3.1×body weight posterior tibial shear. The hip experienced a mean peak loading of 5.5-8.4×body weight and the ankle 8.9-10.0×body weight. INTERPRETATION: The magnitudes of the total (resultant) joint contact forces at the patellofemoral joint, tibiofemoral joint and hip are greater than those reported in activities of daily living and less dynamic rehabilitation exercises. The information in this study is of importance for medical professionals, coaches and biomedical researchers in improving the understanding of acute and chronic injuries, understanding the performance of prosthetic implants and materials, evaluating the appropriateness of jumping and weightlifting for patient populations and informing the training programmes of healthy populations. Copyright © 2012 Elsevier Ltd. All rights reserved

Heteroleptic samarium(III) halide complexes probed by fluorescence-detected L3-edge X-ray absorption spectroscopy

Addition of various oxidants to the near-linear Sm(II) complex [Sm(N††)2] (1), where N†† is the bulky bis(triisopropylsilyl)amide ligand {N(SiiPr3)2}, afforded a family of heteroleptic three-coordinate Sm(III) halide complexes, [Sm(N††)2(X)] (X = F, 2-F; Cl, 2-Cl; Br, 2-Br; I, 2-I). In addition, the trinuclear cluster [{Sm(N††)}3(μ2-I)3(μ3-I)2] (3), which formally contains one Sm(II) and two Sm(III) centres, was isolated during the synthesis of 2-I. Complexes 2-X are remarkably stable towards ligand redistribution, which is often a facile process for heteroleptic complexes of smaller monodentate ligands in lanthanide chemistry, including the related bis(trimethylsilyl)amide {N(SiMe3)2} (N′′). Complexes 2-X and 3 have been characterised by single crystal X-ray diffraction, elemental analysis, multinuclear NMR, FTIR and electronic spectroscopy. The Lα1 fluorescence-detected X-ray absorption spectrum recorded at the Sm L3-edge for 2-X exhibited a resolved pre-edge peak defined as an envelope quadrupole-allowed 2p → 4f transition. The X-ray absorption spectral features were successfully reproduced using time-dependent density functional theoretical (TD-DFT) calculations that synergistically supports the experimental observations as well as the theoretical model upon which the electronic structure and bonding in lanthanide complexes is derived

Devenir enseignant aux États-Unis : politiques, normes et tensions

Trois niveaux de l’« écosystème éducatif » influencent le parcours pour devenir enseignant aux États-Unis : le niveau fédéral, le niveau des États et le niveau local. À chacun de ces niveaux, deux leviers principaux sont utilisés pour agir sur le parcours enseignant : les normes professionnelles pour l’enseignement et les normes pour la formation des enseignants. Cet article s’intéresse à l’influence de ces trois niveaux de l’écosystème éducatif, avant de conclure par une discussion sur les tensions persistantes qui continuent de traverser les voies qui mènent au métier d’enseignant aux États-Unis.Three levels of the educational ecosystem influence the path of becoming a teacher in the United States: the federal level, the state level, and the local level. Each of these levels uses two major levers that influence the path of becoming a teacher: (a) standards for teaching and (b) standards for teacher education. In this paper we address the influence at each of the three relevant levels of the educational ecosystem. We conclude with a discussion of enduring tensions in an individual’s path towards becoming a teacher in the United States.Tres niveles del «ecosistema educativo» influencian la trayectoria para hacerse docente en Estados Unidos: el nivel federal, el nivel de los Estados y el nivel local. En cada uno de estos niveles, se utilizan dos palancas principales para actuar sobre el recorrido de un docente: las normas profesionales para la enseñanza y las normas para la formación de los docentes. Este artículo se interesa por la influencia de estos tres niveles del ecosistema educativo antes de concluir con una discusión sobre las tensiones persistentes que siguen atravesando las vías que conducen al oficio de docente en Estados Unidos

Effects of an 8-week strength training intervention on tibiofemoral joint loading during landing: a cohort study

Objectives To use a musculoskeletal model of the lower limb to evaluate the effect of a strength training intervention on the muscle and joint contact forces experienced by untrained women during landing. Methods Sixteen untrained women between 18 and 28 years participated in this cohort study, split equally between intervention and control groups. The intervention group trained for 8 weeks targeting improvements in posterior leg strength. The mechanics of bilateral and unilateral drop landings from a 30 cm platform were recorded preintervention and postintervention, as was the isometric strength of the lower limb during a hip extension test. The internal muscle and joint contact forces were calculated using FreeBody, a musculoskeletal model. Results The strength of the intervention group increased by an average of 35% (P<0.05; pre: 133±36 n, post: 180±39 n), whereas the control group showed no change (pre: 152±36 n, post: 157±46 n). There were only small changes from pre-test to post-test in the kinematics and ground reaction forces during landing that were not statistically significant. Both groups exhibited a post-test increase in gluteal muscle force during landing and a lateral to medial shift in tibiofemoral joint loading in both landings. However, the magnitude of the increase in gluteal force and lateral to medial shift was significantly greater in the intervention group. Conclusion Strength training can promote a lateral to medial shift in tibiofemoral force (mediated by an increase in gluteal force) that is consistent with a reduction in valgus loading. This in turn could help prevent injuries that are due to abnormal knee loading such as anterior cruciate ligament ruptures,patellar dislocation and patellofemoral pain