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According to the forming process principle,the influence of the tooth profile modification,helix modification and tooth profile deviation,helix deviation and eccentricity tolerance of radial run-out of the involute helical gear on tooth profile shape is analyzed. The curve equations of the involute transverse tooth profile are derived step by step. By using the software,the curve equation of deviation is fitted,and the theoretical curve is replaced by the deviation curve. Then,the actual tooth profile model and solid model including modification and deviation of gear are generated.

The F2 gearbox of Angang Steel Company Limited is introduced. Through the improvement design of the gearbox speed ratio,center distance and bearing of this gearbox and the structure strengthen,the performance of the all aspects of gearbox are improved.

The design,manufacturing and the research and development of high parameter gearbox for generating electricity by utilizing the abandoned residual heat and pressure,residual gas resources of industrial production.

Background: Cryptocaryon irritans infestations on marine teleosts are a considerable burden on factory mariculture. Ultraviolet (UV) light can kill C. irritans under laboratory conditions. However, a rational method for using UV in factory aquaculture to control cryptocaryoniasis has not been developed. This study focused on evaluating the killing effect of UV on protomonts and tomonts of C. irritans and established an automatic UV parasiticide device for the prevention and control of cryptocaryoniasis in marine teleosts. Results: The survival rate of protomonts and tomonts decreased with an increase in the UV irradiation dose. All the protomonts and tomonts died within 14 and 24 min, respectively. The lowest UV lethal doses of protomonts and tomonts of C. irritans were 2.0 × 106 and 3.5 × 106 μWs cm−2, respectively. Exposure of protomonts and tomonts to lethal doses of UV radiation led to shrinkage and severe dissolution of the protoplasm, causing abnormal development of cells. The survival rate of artificially infected Larimichthys crocea (treatment group, group A) was 83.33% at the end of the test (day 14) after disinfection using the automatic UV parasiticide device, whereas that of the control group (group C) was 90.00% (p < 0.05). However, all artificially infected L. crocea without disinfection using the automatic UV parasiticide device (untreated group, group B) died on day 8. Conclusion: The automation of traditional physical methods conforms to the sustainable development of aquaculture and provides a theoretical reference for the prevention and control of cryptocaryoniasis in mariculture. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The Chinese mandarin fish ( Siniperca chuatsi) is currently one of the most important economic freshwater fish in China, whereas the wild resource has declined dramatically in recent years. In this study, we examined the genetic structure and diversity of five populations from the middle reach of the Yangtze River using mitochondrial cytochrome b sequences and microsatellite markers. This research revealed high genetic diversity and low genetic differentiation of S. chuatsi from these regions. The pairwise Fst values of the two markers showed low and no-significant differentiation among populations. AMOVA analysis of two markers and the haplotype genealogy of the Cyt b gene confirmed these results. The STRUCTURE analysis of the microsatellite marker implied that the dam upon the tributary of the Yangtze River blocked the gene flow among those regions. This research will be useful in breeding programs and conservation management of this species. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was conducted to quantify the dietary l-lysine requirement of juvenile Chinese sucker with an initial weight of 1.81 ± 0.04 g reared in indoor flow-through and aerated tanks. Six isonitrogenous and isoenergetic practical diets were formulated to contain graded levels of lysine (1.23%, 1.80%, 2.39%, 2.98%, 3.56% and 4.18% dry matter) at 0.6% increments from dietary ingredients and crystalline l-lysine. Each diet was randomly assigned to triplicate groups of 30 fish each and was fed to apparent satiation by hand three times a day (09:00, 13:00 and 17:00 hours) for 8 weeks. There were significant differences in growth performance and feed utilization among the treatments. Weight gain ( WG), specific growth rate and protein efficiency ratio ( PER) significantly increased with increasing lysine levels up to 2.39% of diet ( P < 0.05) and remained nearly the same thereafter ( P > 0.05). Feed efficiency was the poorest for fish fed the lowest lysine diet ( P < 0.05) and showed no significant differences when dietary lysine level increased from 2.39% to 4.18%. The N retention (% N intake) significantly increased with dietary lysine level but did not attain a plateau ( P < 0.05). Survival could not be related to dietary treatments. Whole body protein increased ( P < 0.05) and whole body lipid decreased ( P < 0.05) with increasing dietary lysine level. The condition factor and hepatosomatic index were significantly affected by dietary lysine levels, however, viscersomatic index, whole body moisture and ash did not differ significantly among dietary treatments. Broken-line analysis on the basis of WG and PER showed that dietary lysine requirements of juvenile Chinese sucker were 2.43% and 2.40% dry diet (5.52% and 5.45% dietary protein) respectively. Based on the ideal protein approach and the A/E ratios determined from muscle amino acid profile an estimation of the EAA requirements of Chinese sucker juveniles were calculated. [ABSTRACT FROM AUTHOR]

In this paper, the complete mitochondrial DNA (mtDNA) sequence ofCoreoperca whiteheadiwas determined. The complete mtDNA genome sequence ofC. whiteheadiis 16,483 bp in length. It consists of 13 protein-coding genes, 22 transfer RNA genes, 2 rRNA genes and 2 non-coding regions. Overall base composition of mitogenome is estimated to be 28.30% for A, 29.33% for C, 16.06% for G and 26.32% for T, respectively, with a high A + T content (54.62%). The complete mitogenome of theC. whiteheadicould contribute to basic researches on population history, molecular systematics and phylogeography. It is also helpful to the reasonable utilization and development of rational management strategies forC. whiteheadiresource. [ABSTRACT FROM AUTHOR]

In this paper, the complete mitochondrial DNA (mtDNA) sequence ofSiniperca undulatewas determined. The complete mtDNA genome sequence ofS. undulatewas 16,504 bp in length. It consisted of 13 protein-coding genes, 22 transfer RNA genes, 2 rRNA genes and 2 non-coding regions. Overall base composition of mitogenome was estimated to be 28.38% for A, 29.43% for C, 16.46% for G and 25.73% for T, respectively, with a high A + T content (54.11%). The complete mitogenome of theS. undulatecan provide a basic data for the studies on population history, molecular systematics, phylogeography, stock evaluation and conservation genetics. It is also helpful to the reasonable utilization and development of rational management strategies forS. undulateresource. [ABSTRACT FROM AUTHOR]