Feasibility of compacted attapulgite/diatomite amended clayey soils as gas barrier materials

Compacted clay liners are extensively used as barriers to control the upward diffusion of vapors of volatile or semi-volatile organic contaminants released from unsaturated contaminated soils at industrycontaminated sites.This study aimed to investigate the gas diffusion barrier performance of compacted clayey soils amended with three agents including attapulgite and diatomite individually,and attapulgite/diatomite mixture.The properties including water retention,volumetric shrinkage,gas diffusion,and unconfined compressive strength were evaluated through a series of laboratory tests of amended compacted clayey soils.The results demonstrate that the decrease in volume proportions of interaggregate pores leads to an increase in unconfined compressive strength(qu).Both hydrophilic groups and microstructures of attapulgite and diatomite result in an increase in water retention percent(Wt)of compacted clayey soil specimens after amendment regardless of the type of agent or initial water content(w0).Furthermore,the ratio of the gas diffusion coefficient(De)to the gas diffusion coefficient in the air(Da)was significantly reduced owing to a decrease in volume proportions of inter-aggregate pores,hydrophilic group,and microstructures of attapulgite and diatomite.Scanning electron microscope analyses revealed that rod-shaped attapulgite filled the inter-aggregate pores formed by clay particles,whereas the disc-shaped diatomite particles,characterized by micropores,failed to obstruct the interaggregate pores due to their larger particle size.Mercury intrusion porosimetry(MIP)analyses showed a reduction in pore volume in the inter-aggregate pores,leading to a reduction in the total pore volume for both the attapulgite and attapulgite/diatomite mixture amended clays,which is in accordance with the scanning electron microscope(SEM)results.The findings are pertinent to the practical application of compacted clay liners as gas barriers against the upward migration of volatile or semi-volatile organic contaminants at contaminated sites.

Preventive electroacupuncture reduces cognitive deficits in a rat model of D-galactose-induced aging

Acupuncture can reduce cognitive deficits in Alzheimer’s disease.However,whether electroacupuncture can prevent or alleviate the cognitive deficits in animal models of aging remains poorly understood.Studies have shown that disordered epigenetic modifications play a critical role in age-related cognitive decline.Therefore,we hypothesized that preventive electroacupuncture might improve cognitive functions during aging by regulating epigenetic modifications.A rat model of aging was produced by intraperitoneal injection of 120 mg/kg D-galactose for 8 weeks.Baihui and Shenshu acupoints were stimulated by electroacupuncture for 8 weeks from the first day of D-galactose administration.Preventive electroacupuncture alleviated memory impairment,decreased tau hyperphosphorylation,and reduced glycogen synthase kinase-3βprotein and mRNA expression levels in the brainstem dorsal raphe nucleus,where intracellular neurofibrillary tangle lesions first occur.In addition,the DNA methylation level in the promoter region of the glycogen synthase kinase-3βgene was increased.The effects of preventive electroacupuncture were stronger than those of preventive acupuncture.Intraperitoneal injection of 0.4 mg/kg 5-aza-2ʹ-deoxycytidine,an inhibitor of DNA methyltransferase that blocks epigenetic modifications,antagonized the effects of preventive electroacupuncture.Our results suggest that preventive electroacupuncture treatment alleviates cognitive impairment in aging rats probably by affecting the epigenetic modification of the glycogen synthase kinase-3βgene in the dorsal raphe nucleus.This study was approved by the Animal Ethics Committee of Hubei University of Chinese Medicine,China(approval No.HUCMS201712001)on November 28,2017.

Analysis of relative wavelength response characterization and its effects on scanned-WMS gas sensing

Our recently proposed three-step method showed the promising potential to improve the accuracy of relative wavelength response(RWR) characterization in the wavelength-modulation spectroscopy(WMS) over the commonly used summation method.A detailed comparison of the three-step method and the summation method,for the wavelength-scanned WMS gas-sensing,was performed with different laser parameters(modulation indexes and scan indexes) and gas properties(pressures and concentrations).Simulation results show that the accuracy of the predicted gas parameters is strongly limited by the RWR characterization with large modulation index and high gas pressure conditions.Both fitting residuals of RWR and errors of predicted gas parameters from the recently proposed three-step method are nearly 2 orders of magnitude smaller than those from the summation method.In addition,the three-step method is further improved by introducing a coupling term for the 2^(nd) harmonic amplitude.Experiments with CO_(2) absorption transition at 6976.2026 cm^(-1) were conducted and validated the simulation analysis.The modified-three-step method presents an improved accuracy in RWR description with at least 5% smaller fitting residual for all conditions compared with the three-step method,although the deviation of the deduced CO_(2) concentrations between these two methods does not exceed 0.2%.

Effect specificity of the early intervention with moxibustion at“BL23”in Alzheimer’s disease rats modeled by ovariectomy and D-Galactose injection

Objective:To observe the effect of the early intervention with moxibustion at "Shènshū(肾俞BL23)" on learning and memory of Alzheimer’s disease(AD) rats modeled by ovariectomy and D-Galactose(D-Gal)injection and the effect on Ca2+/CaMKII/CREB signaling pathway so as to provide the evidence for the acupoint selection in the early intervention with acupuncture and moxibustion for AD.Methods:Sixty female SD rats at the age of 3 months were selected and randomly divided into a normal group,a sham-operation group,a model group,a "BL23" group,a "Wèishū"(胃俞BL21) group,and a non-acupoint group,10 rats in each group.Except in the normal group and the sham-operation group,bilateral ovaries were removed in the other 4 groups.3 days after the operation,D-Gal was injected intraperitoneally at a dose of 150 mg/kg/d for 90 days to establish AD rat model.In the sham-operation group,only the peripheral fat of ovarian was removed and 0.9% normal saline was injected intraperitoneally of the same dose for 90 days.In the "BL23" group,the "BL21" group and the non-acupoints group,since the 2 nd day after ovariectomy,moxibustion was applied at 9:00 a.m.every day in the rats.The rats were fixed on a fixed table,the mild moxibustion with self-prepared moxa stick was applied to bilateral "BL23""BL21" and the non-acupoint of each rat,the ignited end of moxa stick was 2 cm to 3 cm far from skin surface.The infrared thermometer was adopted to measure the temperature of the epidermis of each acupoint from time to time so as to maintain the local temperature to be(41 ± 0.5)℃.Mild moxibustion lasted for 10 min each time,consecutively for 5 days a week and at an interval of 2 days.The total consecutive intervention duration was 12 weeks.In the normal group and the shamoperation group,no moxibustion intervention was performed,but the rats were restricted in a same way during the experiment.At the end of modeling and intervention,water maze test was adopted to detect the learning and memory abilities of rats in each group.The western blotting was used to detect the expressions of p-CREB,p-CaMKII,CaMKII and CREB in hippocampus of rats in each group.Results:(1)Navigation test:since Day 72,compared with the sham-operation group,the escape latencies in all of the consecutive 5 days were longer in the model group(all P <0.05).Since Day 73,compared with the normal group,the escape latency in all of the consecutive 4 days was shorter in the "BL23"group(all P <0.05).(2) Times across platform:compared with the normal group,the number of times consecutively crossing the platform was lower in the model group(P <0.05).After moxibustion,compared with the model group,the number of times across platform was higher in the "BL23"group,indicating a statistical significance(P <0.05).(3)Moving track of water maze spatial probe:the "tendency"strategy was displayed in the normal group and the sham operation group.The "marginal" strategy,which is commonly seen in the AD rats,was displayed in the model group.The "random" strategy was displayed in the "BL23" group.The "marginal" strategy was presented in the "BL21" group and the non-acupoint group.(4) Expressions of hippocampal P-CAMKII,CAMKII,CREB and P-CREB in the rats:compared with the normal group,the phosphorylation degrees of CAMKII and CREB were significantly reduced(both P<0.05) in the model group.In 12 weeks of moxibustion,compared with the model group,the levels of P-CAMKII and P-CREB were increased in the "BL23" group and the "BL21" group(all P <0.05) and the levels in the "BL23" group were higher than that of the "BL21" group and the non-acupoint group(all P<0.05).Conclusion:Moxibustion at "BL23" achieves a better effect in improving the learning and memory of AD rats modeled by ovariectomy and D-Gal injection as compared with moxibustion at "BL21" and the non-acupoint.The effect mechanism is potentially related to the effective activation of Ca2+/CaMKII/CREB signaling pathway.

Chilling rather than photoperiod controls budburst for gymnosperm species in subtropical China

The mechanisms regulating spring phenology have been extensively studied in angiosperm species.However,given that gymnosperms and angiosperms diverged 300 million years ago,phenology may be triggered by different cues in gymnosperm species.The regulatory mechanisms of phenology in subtropical regions remain largely unknown.In combination,it remains untested whether subtropical gymnosperm species have chilling requirements and are photosensitive.We conducted a climate chamber experiment with three chilling and three photoperiod treatments to investigate budburst during an 8-week forcing period.We tested whether budburst of eight gymnosperms species(Cryptomeria japonica,Cunninghamia lanceolata,Cupressus funebris,Ginkgo biloba,Metasequoia glyptostroboides,Pinus massoniana,Pseudolarix amabilis and Podocarpus macrophyllus)was photoperiod sensitive or has strong chilling requirements and whether photoperiod or chilling was more important for advancing budburst.Chilling advanced budburst and increased the percentage of budburst for gymnosperm species.Gymnosperm species required moderate chilling days to advance budburst.Interestingly,the forcing requirement for gymnosperm species was higher than that for angiosperms in the same forest,suggesting that gymnosperms may need more cumulative forcing to initiate budburst than do angiosperms.Compared with temperate gymnosperm species in Germany(194-600℃days),the subtropical species studied here had a much higher forcing requirement(814-1150℃days).The effects of photoperiod were minor,suggesting that chilling outweighs photoperiod in advancing budburst of gymnosperm species in this subtropical region.These results reveal that increased winter temperatures with continued global warming may impact not only angiosperms but also gymnosperms,leading to their delayed spring budburst.

干湿循环作用下氧化镁激发矿渣-膨润土竖向隔离墙耐久特性研究（英文）

目的:1.研究干湿循环作用下氧化镁激发矿渣-膨润土(MSB)竖向隔离墙的耐久特性。2.探讨干湿循环过程中循环级数对隔离墙的质量变化、干密度、p H值、无侧限抗压强度、孔隙结构和微观产物等的影响,并探究MSB的服役性能。创新点:1.通过干湿循环作用,揭示新型MSB隔离墙与传统水泥基(OPC)隔离墙的耐久性差异;2.通过微观分析,成功测定新型MSB隔离墙干湿循环后形成的水化产物。方法:1.通过宏观实验分析,在干湿循环作用下比较MSB隔离墙和OPC隔离墙的质量、干密度、p H值和无侧限抗压强度等参数的变化情况(图2和4~6);2.通过微观分析,研究MSB隔离墙中氧化镁激发高炉矿渣(GGBS-MgO)和膨润土的掺量对空隙结构的影响(图8),并探讨干湿循环作用如何影响碳酸钙和碳酸镁等水化产物的形成(图9)。结论:1.MSB隔离墙的质量损失比OPC隔离墙高1.1%~2.1%;2.MSB和OPC隔离墙的干密度和p H值均随干湿循环级数的增长而减小;3.MSB和OPC隔离墙的无侧限抗压强度随干湿循环级数的增长而降低;4.增加GGBS-Mg O的掺量可减少2%~12%的累计进汞量,而增加膨润土的掺量会增加4.6%~7.9%的进汞量;5.干湿循环可加速碳酸钙和碳酸镁等水化产物的形成。

Effect of the uncertainty in soil-water characteristic curve on the estimated shear strength of unsaturated soil

Most failures or instabilities of geotechnical structures commonly result from shear failure in soil. In addition, many infrastructures are constructed within the unsaturated zone. Therefore, the determination of shear strength of unsaturated soil is crucial in geotechnical design. The soil-water characteristic curve(SWCC) is commonly used to estimate the shear strength of unsaturated soil because the direct measurement is time-consuming and costly. However, the uncertainty associated with the determined SWCC is rarely considered in the estimation of the shear strength. In this paper, the uncertainties of SWCC resulted from different factors are reviewed and discussed. The variability of the estimated shear strength for the unsaturated soil due to the uncertainty of SWCC associated with the best fit process is quantified by using the upper and lower bounds of the determined SWCC. On the other hand, the uncertainties of the estimated shear strength due to different initial void ratios or different confining pressures are quantified by adopting different SWCCs. As a result, it is recommended that the measured SWCC from the conventional Tempe cell or pressure plate needs to be corrected by considering different stress levels in the estimation of the shear strength of unsaturated soil.