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771.
Fengping Li Dong Sun Qiaolin Zhang Hairong Chen István Bíró Zhiyi Zheng Yaodong Gu 《Molecular & cellular biomechanics : MCB》2023,20(1):35-47
Background: A children’s backpack is one of the important school supplies for school-age children. Long-term excessive weight can cause spinal deformity that cannot be reversed. This study compared a double helical spring decompression structure backpack (DHSB) with a traditional backpack (TB) to explore the optimization of decompression devices on upper body pressure. The finite element (FE) method was then used to explore the simulation of lumbar stress with different backpacks, in order to prove that DHSB can reduce the influence of backpack weight on lumbar vertebrae, avoid the occurrence of muscle discomfort and spinal deformity in children; Methods: 18 male children subjects (age: 12.5 ± 0.6 years; height: 145.5 ± 1.9 cm; bodyweight: 40.8 ± 3.1 kg) ran with DHSB and TB at a speed of 3.3 ± 0.2 m/s. Flexible pressure sensors were used to measure the pressure on the shoulder, back, and waist during running. The pressure data was then inputted into the FE model to simulate the effect of carrying different backpacks on the stress of the lumbar intervertebral disc (IVD); Result: There was a significant difference in shoulder and waist peak pressure between the DHSB and TB during the running posture. At a speed of 3.3 ± 0.2 m/s, the peak pressure of the shoulder and waist decreased. After finite element analysis, it was found that carrying DHSB on the back could effectively reduce the intervertebral disc pressure between L4-5 and L5-S1 by 27.9% and 34.1%, respectively; Conclusion: DHSB can effectively reduce the pressure on the shoulder and waist when children are running and can reduce the influence of backpacks on children’s posture to a certain extent. By finite element analysis, it is found that carrying DHSB can effectively reduce the stress of the lumbar intervertebral disc, and the damage to lumbar vertebrae is lower than with a TB. 相似文献
772.
Na Sun Noriko Tamura Tomohiro Tamura Roland Wilhelm Knispel Thomas Hrabe Christine Kofler Stephan Nickell István Nagy 《Proteomics》2009,9(14):3783-3786
We used molecular sieve chromatography in combination with LC‐MS/MS to identify protein complexes that can serve as templates in the template matching procedures of visual proteomics approaches. By this method the sample complexity was lowered sufficiently to identify 464 proteins and – on the basis of size distribution and bioinformatics analysis – 189 of them could be assigned as subunits of macromolecular complexes over the size of 300 kDa. From these we purified six stable complexes of Thermoplasma acidophilum whose size and subunit composition – analyzed by electron microscopy and MALDI‐TOF‐MS, respectively – verified the accuracy of our method. 相似文献
773.
774.
Summary Biological nitrogen fixation is the most important process in which some prokaryotic organisms fix N2 into ammonium. From an agricultural standpoint, biological nitrogen fixation (BNF) is critical because industrial production
of nitrogen fertilizers seldom meets agricultural demands. To increase the BNF is one of the main challenges for the future.
There are different possibilities for extending biological nitrogen fixation to the economically important plants. One of
the possibilities is to create new artificial systems between diazotrophic bacteria and different higher plants. This is the
main topic of the present review article which discusses the establishment of new associative and/or symbiotic systems, via
introduction of diazotrophic bacteria into the roots by different methods; and incorporation of nitrogen-fixing bacteria in
the entire plant by in vitro methods, through the establishment of intracellular endosymbioses via induced uptake of bacteria by plant protoplasts (endocytobiosis),
and establishment of intercellular associations by forced introduction of bacteria into the plant tissues (exocytobiosis).
The common characteristic of the methods to create artificial plant-microbe systems for atmospheric nitrogen fixation is the
use of in vitro plant systems: cells, tissues and organ cultures. The review pays particular attention to new bacterial inoculation procedures
for introduction of the diazotrophic bacteria inside the plant tissues. 相似文献
775.
The prisoner's dilemma (PD) and the snowdrift (SD) games are paradigmatic tools to investigate the origin of cooperation. Whereas spatial structure (e.g. nonrandom spatial distribution of strategies) present in the spatially explicit models facilitates the emergence of cooperation in the PD game, recent investigations have suggested that spatial structure can be unfavourable for cooperation in the SD game. The frequency of cooperators in a spatially explicit SD game can be lower than it would be in an infinitely large well-mixed population. However, the source of this effect cannot be identified with certainty as spatially explicit games differ from well-mixed games in two aspects: (i) they introduce spatial correlations, (ii) and limited neighbourhood. Here we extend earlier investigations to identify the source of this effect, and thus accordingly we study a spatially explicit version of the PD and SD games with varying degrees of dispersal and neighbourhood size. It was found that dispersal favours selfish individuals in both games. We calculated the frequency of cooperators at strong dispersal limit, which in concordance with the numerical results shows that it is the short range of interactions (i.e. limited neighbourhood) and not spatial correlations that decreases the frequency of cooperators in spatially explicit models of populations. Our results demonstrate that spatial correlations are always beneficial to cooperators in both the PD and SD games. We explain the opposite effect of dispersal and neighbourhood structure, and discuss the relevance of distinguishing the two effects in general. 相似文献
776.
Characterization of synchronization in interacting groups of oscillators: application to seizures
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We investigate the emergence of synchronization in two groups of oscillators; one group acts as a synchronization source, and the other as the target. Based on phase model simulations, we construct a synchrony index (SI): a combination of intra- and intergroup synchronies. The SI characterizes the extent of induced synchrony in the population. We demonstrate the usefulness of the measure in a test case of mesial temporal lobe epilepsy: the SI can be readily calculated from standard electroencephalographic measurements. We show that the synchrony index has a statistically significant increased value for the ictal periods and that the epileptic focus can be located by identifying the most synchronous pairs of electrodes during the initial part of ictal period of the seizure. We also show that it is possible in this pilot case to differentiate clinical and subclinical seizures based on the dynamical features of the synchronization. The synchronization index was found to be a useful quantity for the characterization of “pathological hypersynchronization” within a well-characterized patient with mesial temporal lobe epilepsy and thus has potential medical value in seizure detection, localizing ability, and association with later surgical outcome. 相似文献
777.
Máthé Csaba Hamvas Márta M. Grigorszky István Vasas Gábor Molnár Erika Power J. Brian Davey Michael R. Borbély George 《Plant Cell, Tissue and Organ Culture》2000,63(1):81-84
Embryogenic cultures of the common reed [Phragmites australis (Cav.) Trin. Ex. Steud.] were induced on Murashige and Skoog (1962)-based medium with 2% (w/v) sucrose, B5 vitamins and 4.5
μM 2,4-dichlorphenoxyacetic acid. Four independent culture lines, two initiated from stem nodes and two from roots, were established.
These cultures underwent somatic embryogenesis. In one line of stem node origin, the somatic embryos germinated and developed
into plants, following transfer of embryogenic cultures to Murashige and Skoog (1962)-based medium lacking growth regulators,
with 108 ± 17 plants being recovered per 100 mg fresh weight of culture. In other lines, the somatic embryos developed roots,
but not shoots. Shoot regeneration via somatic embryogenesis offers potential as anin vitro system for physiological studies, including assessments of the response of common reed to environmental pollutants.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
778.
Borza I Kolok S Gere A Nagy J Fodor L Galgóczy K Fetter J Bertha F Agai B Horváth C Farkas S Domány G 《Bioorganic & medicinal chemistry letters》2006,16(17):4638-4640
A novel series of benzimidazole-2-carboxamide derivatives was prepared and identified as NR2B selective NMDA receptor antagonists. The influence of some structural elements, like H-bond donor groups placed on the benzimidazole skeleton and the substitution pattern of the piperidine ring, on the biological activity was studied. Compound 6a showed excellent analgetic activity in the mouse formalin test following po administration. 相似文献
779.
The application of a chiral ligand-exchange column (CLEC) for the direct high-performance liquid chromatographic enantioseparation of unusual secondary amino acids using D-penicillamine-Cu(II) complex as chiral selector is reported. The amino acids investigated were pyrrolidine-2-carboxylic acid, piperidine-2-carboxylic acid, piperazine-2-carboxylic acid, morpholine-3-carboxylic acid, and thiomorpholine-3-carboxylic acid analogs. Chromatographic results are given as the retention, separation, and resolution factors. The chromatographic conditions were varied to achieve optimal separation. The elution sequence of the enantiomers was determined and in most cases the S isomer eluted before R. 相似文献
780.
Kovács M Szendro Z Milisits G Bóta B Bíró-Németh E Radnai I Pósa R Bónai A Kovács F Horn P 《Reproduction, nutrition, development》2006,46(2):205-210
The effect of nursing method and ingestion of maternal faeces on the development of the bacteroides, lactobacillus and coliform flora of the caecum in the first 10 days of life were examined in freely nursed pups having access to maternal faeces (Group FF), pups nursed once a day and having access (Group CF), or having no access (Group CN) to maternal faeces. Colonisation of the caecum by Bacteroides commenced already on day 3 after birth. On day 2 the bacteroides counts were below 100, while on day 4 they were already between 100 and 10,000. In Group CN, the Bacteroides counts were lower (by 14 to 40%) throughout the 10-day period studied than in the groups having access to maternal faeces. Differences between groups were significant only on days 4 and 6. The average number of maternal faecal pellets left behind the doe in Group CN was 3-4 (between 0.5 and 6.4 per doe). In Groups FF and CF the pellets became smaller, crumbled and finally disappeared from the nest box, they were consumed by the pups and could be found in their gastric content. The lactobacillus counts decreased in all three groups with age, from 6.0 to 3.5 log10 CFU.g-1 (FF), 4.6 to 2.8 log10 CFU.g-1 (CF) and 5.1 to 3.1 log10 CFU.g-1 (CN), respectively. The coliform counts were higher in the first 4 days in FF (5.6 log10 CFU.g-1) than in CF (< 2 log10 CFU.g-1) and CN (2-3.6 log10 CFU.g-1) animals. Bacteroides could be cultured from the surface of the vulvar labia (max. 1000 colony count) and the vagina (max. 190 colony count), so young rabbits could become "infected" by them already in the doe's vagina. Thus prevention of ingestion of maternal faeces only slightly influenced the development of the bacteroides flora, the faeces left behind by the doe did not play an exclusive role in their colonisation. 相似文献