In order to improve the efficiency of the desulfurization process utilizing the mechanical stirring method, the effect of flux dispersion on the hot metal desulfurization reaction was investigated in 1/8-scale water model and 70 kg-scale hot metal experiments.Flux dispersion behavior is divided into three stages, i.e., "non-dispersion," "transition," and "complete dispersion." The desulfurization rate increases remarkably from the "non-dispersion" to the "complete dispersion" stage, corresponding to the change in the condition of particle dispersion.The relationship between the impeller position and the vortex depth is defined as the dispersion index, I. When the dispersion index was over 1, complete dispersion occurred in water model experiments, and the apparent rate constant increased remarkably in hot metal experiments.The observed diameter of the desulfurization slag was 1.4 mm, which is in good agreement with the calculated value, 1.55 mm. This means that fine desulfurization flux aggregates immediately after the addition of the flux. In order to increase desulfurization efficiency, it is important to control this particle aggregation.

BackgroundIn this study, we investigated the effects of resistance training protocols with different loads on muscle hypertrophy and strength.MethodsTwenty-one participants were randomly assigned to 1 of 3 (n = 7 for each) resistance training (RT) protocols to failure: High load 80 % 1RM (8–12 repetitions) (H group), low load 30 % 1RM (30–40 repetitions) (L group) and a mixed RT protocol (M group) in which the participants switch from H to L every 2 weeks. RT consisted of three sets of unilateral preacher curls performed with the left arm 3 times/week with 90 s rest intervals between sets. The right arm served as control. Maximum voluntary contraction (MVC) of the elbow flexors (elbow angle: 90°) and rate of force development (RFD, 0–50, 50–100, 100–200 and 200–300 ms) were measured. Cross-sectional area (CSA) of the elbow flexors was measured via magnetic resonance imaging (MRI). All measurements were conducted before and after the 8 weeks of RT (72–96 h after the last RT). Statistical evaluations were performed with two-way repeated measures (time × group).ResultsAfter 8 weeks of 3 weekly RT sessions, significant increases in the left elbow flexor CSA [H: 9.1 ± 6.4 % (p = 0.001), L: 9.4 ± 5.3 % (p = 0.001), M: 8.8 ± 7.9 % (p = 0.001)] have been observed in each group, without significant differences between groups. Significant changes in elbow flexor isometric MVC have been observed in the H group (26.5 ± 27.0 %, p = 0.028), while no significant changes have been observed in the M (11.8 ± 36.4 %, p = 0.26) and L (4.6 ± 23.9 %, p = 0.65) groups. RFD significantly increased during the 50–100 ms phase in the H group only (p = 0.049).ConclusionsWe conclude that, as long as RT is conducted to failure, training load might not affect muscle hypertrophy in young men. Nevertheless, strength and RFD changes seem to be load-dependent. Furthermore, a non-linear RT protocol switching loads every 2 weeks might not lead to superior muscle hypertrophy nor strength gains in comparison with straight RT protocols.

Our results suggest that the ESR1 rs2234693 C allele, in contrast to the T allele, provides protection against muscle injury by lowering muscle stiffness.Single nucleotide polymorphism; estrogen receptor; muscle stiffness; injury prediction; athletes.

The purpose of this study was to clarify the heritability estimates of human muscle strength-related phenotypes (H -msp). A systematic literature search was conducted using PubMed (through August 22, 2016). Studies reporting the H -msp for healthy subjects in a sedentary state were included. Random-effects models were used to calculate the weighted mean heritability estimates. Moreover, subgroup analyses were performed based on phenotypic categories (eg, grip strength, isotonic strength, jumping ability). Sensitivity analyses were also conducted to investigate potential sources of heterogeneity of H -msp, which included age and sex. Twenty-four articles including 58 measurements were included in the meta-analysis. The weighted mean H -msp for all 58 measurements was 0.52 (95% confidence intervals [CI]: 0.48-0.56), with high heterogeneity (I =91.0%, P<.001). Subgroup analysis showed that the heritability of isometric grip strength, other isometric strength, isotonic strength, isokinetic strength, jumping ability, and other power measurements was 0.56 (95% CI: 0.46-0.67), 0.49 (0.47-0.52), 0.49 (0.32-0.67), 0.49 (0.37-0.61), 0.55 (0.45-0.65), and 0.51 (0.31-0.70), respectively. The H -msp decreased with age (P<.05). In conclusion, our results indicate that the influence of genetic and environmental factors on muscle strength-related phenotypes is comparable. Moreover, the role of environmental factors increased with age. These findings may contribute toward an understanding of muscle strength-related phenotypes.

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The purpose of this study was to investigate the effects of the T1470A polymorphism (rs1049434) on power-oriented performance and lactate concentration during or after cycling sprints in Japanese wrestlers. Participants (199 wrestlers and 649 controls) were genotyped for the T1470A genotype (rs1049434) using the TaqMan Assay. All wrestlers were international (n=77) or national (n=122) level athletes. Among them, 46 wrestlers performed 2 anaerobic performance tests, a 30-s Wingate Anaerobic test (WAnT) and a series of 10 maximal effort 10-s sprints on a cycle ergometer. Blood lactate levels were measured before, during, and after the tests. In the A-allele recessive model (AA vs. TA+TT), the frequency of the AA genotype was significantly higher in all wrestlers than in controls (p=0.037). Wrestlers with AA genotype had lower blood lactate concentrations than those with TA+TT genotype at 10 min after the WAnT and following the 5 and the final set of repeated cycling sprints (p<0.05). The AA genotype of the T1470A polymorphism is over-represented in wrestlers compared with controls and is associated with lower blood lactate concentrations after 30-s WAnT and during intermittent sprint tests in Japanese wrestlers.

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