Effects of gravel on the water absorption characteristics and hydraulic parameters of stony soil

The eastern foothills of the Helan Mountains in China are a typical mountainous region of soil and gravel,where gravel could affect the water movement process in the soil.This study focused on the effects of different gravel contents on the water absorption characteristics and hydraulic parameters of stony soil.The stony soil samples were collected from the eastern foothills of the Helan Mountains in April 2023 and used as the experimental materials to conduct a one-dimensional horizontal soil column absorption experiment.Six experimental groups with gravel contents of 0%,10%,20%,30%,40%,and 50%were established to determine the saturated hydraulic conductivity(K_(s)),saturated water content(θ_(s)),initial water content(θ_(i)),and retention water content(θ_(r)),and explore the changes in the wetting front depth and cumulative absorption volume during the absorption experiment.The Philip model was used to fit the soil absorption process and determine the soil water absorption rate.Then the length of the characteristic wetting front depth,shape coefficient,empirical parameter,inverse intake suction and soil water suction were derived from the van Genuchten model.Finally,the hydraulic parameters mentioned above were used to fit the soil water characteristic curves,unsaturated hydraulic conductivity(K_(θ))and specific water capacity(C(h)).The results showed that the wetting front depth and cumulative absorption volume of each treatment gradually decreased with increasing gravel content.Compared with control check treatment with gravel content of 0%,soil water absorption rates in the treatments with gravel contents of 10%,20%,30%,40%,and 50%decreased by 11.47%,17.97%,25.24%,29.83%,and 42.45%,respectively.As the gravel content increased,inverse intake suction gradually increased,and shape coefficient,K_(s),θ_(s),andθ_(r)gradually decreased.For the same soil water content,soil water suction and K_(θ)gradually decreased with increasing gravel content.At the same soil water suction,C(h)decreased with increasing gravel content,and the water use efficiency worsened.Overall,the water holding capacity,hydraulic conductivity,and water use efficiency of stony soil in the eastern foothills of the Helan Mountains decreased with increasing gravel content.This study could provide data support for improving soil water use efficiency in the eastern foothills of the Helan Mountains and other similar rocky mountainous areas.

AN EXPERIMENTAL STUDY ON NASAL ABSORPTION OF GENTAMYCIN IN DOGS

Drug absorptive function of the nasal mucosa has been a new and interesting subject of research in bridging rhinology and pharmacology. The authors applied a solution of gentamycin at a concentration of 40 mg/ml to 15 dogs at a dosage of 5 mg/kg for each through three routes of administration, ie, the intravenous, intramuscular and iutranasal. The serum levels of gentamyciu from 0 to 180 minutes after receiving the drug were determined with thin-layer scanning chromatographic method. It was found that if the bioavailability of the intravenous route was considered as 100%, the bioavailability of the intranasal route was 80.5%,and that of the intramuscular route was 42％. After giving drops of the drug into nasal cavity in above-mentioned dosage,the serum drug level reached a peak in 10 to 30 min ranging in 3.7 to 6.6 μg/ml. The half-life period of the drug given through this route was about three hours, indicating that the na sal mucosa is apt to be penetrated by gentamycin and allows the drug to be abso

Experimental observation of surface phonon absorption in Zn fine particles coated with ZnO

FINE particles have attracted much attention in the past few years due to their unique physical and chemical properties. For gas-evaporated fine metallic particles, a thin oxide layer is usually formed on their surface. According to Ruppin’s prediction, a dielectric coating on metallic particles should have a series of surface modes between ωTO and ωLO, the long-wavelength transverse and longitudinal optical phonon frequencies of the dielectric. The frequency of