Frost heave control of fine round gravel fillings in deep seasonal frozen regions

Fine round gravel soil is widely employed in the subgrade of high and thawing. The lower the fines content in fine round gravel soil, but compaction difficulty increases. This study is to obtain the speed railways in cold regions to prevent frost heaving the smaller the quantities of frost heaving and thawing, optimum fines content and limited frost heaving and thawing. The fine round gravel soil filling （FRGSF） used in the Harbin-Qiqihaer Passenger Dedicated Line is taken as the study object. Influence of fines content on optimum water content, maximum dry density and frost heaving properties of FRGSF were studied by means of compaction and frost heaving tests. Results show that the maximum dry density of the FRGSF increases first and then decreases with an increase of fines content, namely there is an optimum fines content for easy compaction. The method of surface-vibratory instrument is fit for coarse-grained soils, and wet state of coarse-grained soil is in favor of compaction. Considering the relationship of fines content with maximum dry density and the frost heaving ratio of FRGSF, the fines content should be limited to within the range of 9%-10%, so that the frost heaving ratio is less than 1%, and the FRGSF is easily compacted. Water supply is proved to be an important factor influencing the amount of frost heaving of FRGSF. We also conclude that in the field, it is imperative to control waterproofing and drainage measures.

Analysis of temperature field characteristics based on subgrade site measurements of Harbin-Qiqihar High-speed Railway in a deep seasonal frozen soil region

Recent years have seen a large number of high-speed railways built and will be built in seasonal frozen soil regions ot China. Although high-speed railways are characterized by being fast, comfortable and safe, higher standards for defor- mation of the railways＇ frozen subgrade are required. Meanwhile, changes in subgrade soil temperatures are the main factors affecting the deformation of frozen subgrade. Therefore, this paper selected typical test subgrade sections of the Harbin-Qiqihar Line, a special line for passenger transport built in the deep seasonal frozen soil regions of China, to monitor field temperatures. Also, the temperature changing laws of railways＇ subgrade in this region was analyzed by using testing data, the aim of which is to provide a technical support for future design and construction of buildings and structures in a deep seasonal frozen soil region.

Influence of fines content on the anti-frost properties of coarse-grained soil

This paper aims to determine the optimal fines content of coarse-grained soil required to simultaneously achieve weaker frost susceptibility and better bearing capacity. We studied the frost susceptibility and strength properties of coarse-grained soil by means of frost heaving tests and static triaxial tests, and the results are as follows： （1） the freezing temperature of coarse-grained soil decreased gradually and then leveled off with incremental increases in the percent content of fines; （2） the fines content proved to be an important factor influencing the frost heave susceptibility and strength properties of coarse-grained soil. With incremental increases in the percent content of fines, the frost heave ratio increased gradually and the cohesion function of fines effectively enhanced the shear strength of coarse-grained soil before freeze-thaw, but the frost susceptibility of fines weakened the shear strength of coarse-grained soil after freeze-thaw; （3） with increasing numbers of freeze-thaw cycles, the shear strength of coarse-grained soil decreased and then stabilized after the ninth freeze-thaw cycle, and therefore the mechanical indexes of the ninth freeze-thaw cycle are recommended for the engi- neering design values; and （4） considering frost susceptibility and strength properties as a whole, the optimal fines content of 5% is recommended for railway sub,fade coarse-~rained soil fillings in frozen re^ions.

Addition of peroxiredoxin 6 (PRDX6) to IVF fertilization medium maintains motility and longevity of human spermatozoa

This study aims to investigate the protective effects of peroxiredoxin 6 on the total motility and progressive motility of human spermatozoa.Semen samples with normal parameters were collected from 23 males and supplemented with different concentrations of peroxiredoxin 6.All the semen samples were measured according to the WHO 5th manual,and the motile spermatozoa were extracted using IVF fertilization medium supplemented with different peroxiredoxin 6 concentrations.Total motility and progressive motility were observed at different time-points of culture at room temperature.After peroxiredoxin 6 supplementation,all groups had a significant increase in total motility and progressive motility compared to the control group.The difference in total motility and progressive motility between the 0 and 10−7 mM groups was observed at 24 and 48 h of culture at room temperature.At 24 h,the total motility increased by 30%in the control group(16.03±11.91 vs.11.51±7.84),and progressive motility increased by 21%(10.53±9.4 vs.8.31±6.04).A similar trend was observed in the 48 h group.In addition,we also found that peroxiredoxin 6 had a well protective effect on sperm kinetic parameters at 10−7 mM.The findings of this study suggest that peroxiredoxin 6 can enhance sperm total motility and progressive motility in IVF fertilization medium.Peroxiredoxin 6 may have potential benefits for sperm preparation in assisted reproductive technology.

Leptin effects on the hypothalamic-pituitary-gonadal axis by activating proopiomelanocortin neurons Correlation between regulatory effects and duration

BACKGROUND：Leptin preserves reproductive functions by stimulating hypothalamic-pituitary-gonadal axis activities at different levels.Some interneurons play an important role in leptin regulation of the gonadal axis.It remains uncertain whether leptin regulates reproductive functions by activating proopiomelanocortin （POMC） neurons.OBJECTIVE：To investigate leptin effects on secretory function of the neuroendocrine-gonadal axis by activating POMC neurons and to observe and verify the relationship between leptin effects and various time points.DESIGN,TIME AND SETTING：The randomized,controlled,animal study was performed at the Basic Institute of Chengde Medical University and the Research Room of Reproductive Immunology of National Research Institute for Family Planning from June to September 2008.MATERIALS：Leptin （Peprotech,USA）,a-melanocyte stimulating hormone and rabbit anti-POMC polyclonal antibody （SC-20148） （Santa Cruz Biotechnology,USA）,follicle stimulating hormone,luteinizing hormone,and gonadotropin releasing hormone enzyme-labeled immunosorbent assay （ELISA） kit （ADL,USA） were used in the present study.METHODS：A total of 60 healthy,female,adult,Wistar rats received 17 （3-estradiol for 5 consecutive days at 15 days after ovariectomy.The rats were randomly assigned to physiological saline （n= 35）,leptin （n = 35）,and a-melanocyte stimulating hormone （n = 20） groups.MAIN OUTCOME MEASURES：Changes in gonadotropin releasing hormone,luteinizing hormone,and follicle stimulating hormone were compared following intraventricular injection of physiological saline,leptin,and a-melanocyte stimulating hormone at various time points.Changes in POMC mRNA and protein expression in the hypothalamus were measured following physiological saline and leptin injection via the lateral ventricle.RESULTS：Compared to the physiological saline group,leptin and a-melanocyte stimulating hormone affected secretion in the hypothalamus-pituitary axis.Leptin affected secretion of gonadotropin releasing hormone,luteinizing hormone,and follicle stimulating hormone,whereas a-melanocyte stimulating hormone inhibited secretion of these hormones.Compared to the physiological saline group,POMC mRNA expression was significantly increased in the hypothalamus at 2 and 4 hours after leptin injection （P〈 0.05）,but expression recovered to physiological saline group levels at 6 hours after injection （P 〉 0.05）.POMC protein expression was significantly increased in the hypothalamus at 4 and 6 hours after leptin injection （P〈 0.05）.CONCLUSION：Leptin affects secretory function of the neuroendocrine-gonadal axis through combined effects on POMC neurons and other pathways.Results suggested that the regulatory effects of POMC neurons were later compared to other neurons.

Melatonin and its protective role against male reproductive toxicity induced by heavy metals,environmental pollutants,and chemotherapy:A review

Melatonin,as a ubiquitous indoleamine hormone,is synthesized primarily by the pineal gland.It has diverse biological effects through quite complex mechanisms.More recently,studies have focused on the mechanism of melatonin in anti-reproductive toxicity/damage.Since melatonin possesses strong antioxidant and anti-apoptotic properties,researchers have examined its potential role in protecting against male reproductive toxicity/damage,which may be induced by chemotherapy or environmental toxicants and can lead to male infertility.In this article,recent progress regarding the protective effects of melatonin on male reproductive toxicity/damage is reviewed.

Effect of peroxiredoxin 6 on total and progressive motility of human spermatozoa after cryopreservation

Sperm cryopreservation is useful in assisted reproductive technology and male fertility preservation.However,freezing and thawing significantly reduces the total and progressive motility of human spermatozoa.In the present study,we explored the effects of peroxiredoxin 6(PRDX6)on total and progressive motility of human spermatozoa after cryopreservation.Semen samples of 20 males with normal parameters were collected and frozen in media supplemented with different concentrations of PRDX6(0 mM,10−5 mM,10−7 mM,and 10−9 mM,respectively).Postthaw total and progressive motility of sperms were measured.The results showed that in comparison with 0 mM,the concentrations of 10−5 mM,10−7 mM,and 10−9 mM of PRDX6 all significantly improved total motility and progressive motility of sperms(p<0.05).The 10−7 mM of PRDX6 showed the best performance.In conclusion,the supplementation of PRDX6 helps to maintain the total and progressive motility of human spermatozoa.