Subchronic Oral Toxicity Evaluation of Lanthanum： A 90-day, Repeated Dose Study in Rats

Objective The present study was undertaken to evaluate the subchronic toxicity of lanthanum and to determine the no observed adverse effect level（NOAEL）,which is a critical factor in the establishment of an acceptable dietary intake（ADI）.Methods In accordance with the Organization for Economic Co-operation and Development（OECD） testing guidelines,lanthanum nitrate was administered once daily by gavage to Sprague-Dawley（SD） rats at dose levels of 0,1.5,6.0,24.0,and 144.0 mg/kg body weight（BW） per day for 90 days,followed by a recovery period of 4 weeks in the 144.0 mg/kg BW per day and normal control groups.Outcome parameters were mortality,clinical symptoms,body and organ weights,serum chemistry,and food consumption,as well as ophthalmic,urinary,hematologic,and histopathologic indicators.The benchmark dose（BMD） approach was applied to estimate a point of departure for the hazard risk assessment of lanthanum.Results Significant decreases were found in the 144.0 mg/kg BW group in the growth index,including body weight,organ weights,and food consumption.This study suggests that the NOAEL of lanthanum nitrate is 24.0 mg/kg BW per day.Importantly,the 95% lower confidence value of the benchmark dose（BMDL） was estimated as 9.4 mg/kg BW per day in females and 19.3 mg/kg BW per day in males.Conclusion The present subchronic oral exposure toxicity study may provide scientific data for the risk assessment of lanthanum and other rare earth elements（REEs）.

Rheological Behavior of Basalt Fiber Reinforced Asphalt Mastic

The characters of basalt fiber are analyzed and compared with commonly used fibers. The rheological behaviors of the basalt fiber reinforced asphalt mastic are investigated by the dynamic shear rheological tests and the repeated creep tests. The results show that basalt fiber has excellent reinforced performances, such as high asphalt absorption ratio, low water absorption ratio, high tensile strength, high elastic modulus and high temperature stability. The rutting factor of the fiber reinforced asphalt mastic is higher than the plain asphalt mastic and the reinforced effects are more remarkable under high temperature. The rheological performances of the asphalt mastic demonstrate a good linear relationship between different temperature and loading frequency. The creep stiffness modulus of the asphalt mastic at different loading time can be expressed by power function. Improved Burgers model is used to represent the rheological behaviors of the asphalt mastic with basalt fiber and the model parameters are estimated.

Experimental study on permanent deformation characteristics of coarse-grained soil under repeated dynamic loading

Practical assessment of subgrade settlement induced by train operation requires developing suitable models capable of describing permanent deformation characteristics of subgrade filling under repeated dynamic loading.In this paper,repeated load triaxial tests were performed on coarse-grained soil(CGS),and the axial permanent strain of CGS under different confining pressures and dynamic stress amplitudes was analysed.Permanent deformation behaviors of CGS were categorized based on the variation trend of permanent strain rate with accumulated permanent strain and the shakedown theory.A prediction model of permanent deformation considering stress state and number of load cycles was established,and the ranges of parameters for different types of dynamic behaviors were also divided.The results indicated that the variational trend of permanent strain rate with accumulated permanent strain can be used as a basis for classifying dynamic behaviors of CGS.The stress state(confining pressure and dynamic stress amplitude)has significant effects on the permanent strain rate.The accumulative characteristics of permanent deformation of CGS with the number of load cycles can be described by a power function,and the model parameters can reflect the influence of confining pressure and dynamic stress amplitude.The study’s results could help deepen understanding of the permanent deformation characteristics of CGS.

Subchronic Oral Toxicity Evaluation of Sodium Dehydroacetate: A 90-day Repeated Dose Study in Rats

Objective The present study was undertaken to evaluate the subchronic oral toxicity of sodium dehydroacetate(DHA-Na)and to determine the point of departure(POD),which is a critical factor in the establishment of an acceptable dietary intake.Methods DHA-Na was administered once daily by gavage to Sprague–Dawley rats at dose levels of 0.0,31.0,62.0,and 124.0 mg/kg BW per day for 90 days,followed by a recovery period of 4 weeks in the control and 124.0 mg/kg BW per day groups.The outcome parameters were mortality,clinical observations,body weights,food consumption,hematology and clinical biochemistry,endocrine hormone levels,and ophthalmic,urinary,and histopathologic indicators.The benchmark dose(BMD)approach was applied to estimate the POD.Results Significant decreases were found in the 62.0 and 124.0 mg/kg BW groups in terms of the body weight and food utilization rate,whereas a significant increase was found in the thyroid stimulating hormone levels of the 124.0 mg/kg BW group.Importantly,the 95%lower confidence limit on the BMD of 51.7 mg/kg BW was modeled for a reduction in body weight.Conclusion The repeated-dose study indicated the slight systemic toxicity of DHA-Na at certain levels(62.0 and 124.0 mg/kg BW)after a 90-day oral exposure.

A Face Serum Containing Palmitoyl Tripeptide-38, Hydrolyzed Hyaluronic Acid, Bakuchiol and a Polyherbal and Vitamin Blend Improves Skin Quality

A face serum composed of a combination of biologically active compounds was evaluated for safety and efficacy in vitro, in a repeat insult patch test and in a human clinical efficacy trial. The serum inhibited tyrosinase activity modestly, decreased collagenase activity and exhibited notable free radical scavenging activity in vitro. It is gentle to the skin, as the serum did not irritate the skin or produce symptoms of allergic contact dermatitis in the 55 healthy adults that participated in the repeat insult patch test. In the efficacy trial, daily application of the face serum for 30 days significantly increased skin hydration, with all 35 volunteers experiencing improvement. Substantial improvements in skin elasticity, roughness (fine lines and wrinkles), and brightness also occurred during the trial. Dermatological examination also revealed a trend for reduced comedone count with use of the serum. Self-assessment responses revealed that all volunteers experienced improvements in multiple skin quality parameters and that participant perceptions are consistent with the results of the instrumental analyses. These findings indicated that the measured improvements in skin quality are not only statistically significant but are also clinically relevant as they were great enough for users of the face serum to feel and recognize.

Hysteresis analysis of graphene transistor under repeated test and gate voltage stress

The current transport characteristic is studied systematically based on a back-gate graphene field effect transistor, under repeated test and gate voltage stress. The interface trapped charges caused by the gate voltage sweep process screens the gate electric field, and results in the neutral point voltage shift between the forth and back sweep direction. In the repeated test process, the neutral point voltage keeps increasing with test times in both forth and back sweeps, which indicates the existence of interface trapped electrons residual and accumulation. In gate voltage stress experiment, the relative neutral point voltage significantly decreases with the reducing of stress voltage, especially in -40 V, which illustrates the driven-out phenomenon of trapped electrons under negative voltage stress.

Crushed rocks stabilized with organosilane and lignosulfonate in pavement unbound layers:Repeated load triaxial tests

The creation of the new“Ferry-Free Coastal Highway Route E39”in southwest Norway entails the production of a remarkable quantity of crushed rocks.These resources could be beneficially employed as aggregates in the unbound courses of the highway itself or other road pavements present nearby.Two innovative stabilizing agents,organosilane and lignosulfonate,can significantly enhance the key properties,namely,resilient modulus and resistance against permanent deformation,of the aggregates that are excessively weak in their natural state.The beneficial effect offered by the additives was thoroughly evaluated by performing repeated load triaxial tests.The study adopted the most common numerical models to describe these two key mechanical properties.The increase in the resilient modulus and reduction in the accumulated vertical permanent deformation show the beneficial impact of the additives.Furthermore,a finite element model was created to simulate the repeated load triaxial test by implementing nonlinear elastic and plastic constitutive relationships.

Evaluation of repeated exposure systemic toxicity test of PVC with new plasticizer on rats via dual parenteral routes

Systemic toxicity caused by repeated exposure to both polar and nonpolar leachables of di(2-ethylhexyl)-1,2-cyclohexane plasticized polyvinyl chloride(PVC)was evaluated with dual routes of parenteral administration method on rats in the study.Experimental group and control group were designed by researchers.Tail intravenous injection with 0.9%sodium chloride injection extracts and intraperitoneal injection with corn oil extracts were conducted to the experimental rats while tail intravenous injection with 0.9%sodium chloride Injection and intraperitoneal injection with corn oil were conducted to the control rats.After 14 days,blood specimens were collected for clinical pathology(hematology and clinical chemistry)analysis.Selected organs were weighed and a histopathological examination was conducted.As a result,compared with the control animals,there were no toxicity-related changes on the parameters above.The results show that the rats do not show obvious systemic toxicity reaction caused by repeated exposure with dual routes of parenteral administration method on rats after administration with both polar and nonpolar exacts of di(2-ethylhexyl)-1,2-cyclohexane plasticized PVC simultaneously up for 14 days.

Performances of hydrated cement treated crushed rock base for Western Australian roads

The resilient modulus （RM） of hydrated cement treated crushed rock base （HCTCRB） affected by amount of hydration periods, compaction and dryback processes was presented using repeated load triaxial tests. The related trends of RM corresponding to the different hydration periods still cannot be concluded. Instead, It is found that the moisture content plays more major influence on the RM performance. Higher additional water during compaction of HCTCRB, even at its optimum moisture content and induced higher dry density, led to the inferior RM performance compared to the sample without water addition. The RM of damper samples can be improved through dryback process and superior to that of the sample without water addition at the same moisture content. However, the samples withut water addition during compaction deliver the comparable RM values even its dry density is lower than the other two types. These results indicate the significant influence of moisture content to the performances of HCTCRB with regardless of the dry density. Finally, the experimental results of HCT- CRB and parent material are evaluated with the K-O model and the model recommended by Austroads. These two models provide the excellent fit of the tested results with high degree of determination.