Cellulose nanofiber (CNF) aerogels with favorable floatability and mucoadhesive properties prepared by the freeze-drying method have been introduced as new possible carriers for oral controlled drug delivery system. Bendamustine hydrochloride is considered as the model drug. Drug loading was carried out by the physical adsorption method, and optimization of drug-loaded formulation was done using central composite design. A very lightweight-aerogel-with-matrix system was produced with drug loading of 18.98%±1.57%. The produced aerogel was characterized for morphology, tensile strength, swelling tendency in media with different pH values, floating behavior, mucoadhesive detachment force and drug release profiles under different pH conditions. The results showed that the type of matrix was porous and woven with excellent mechanical properties. The drug release was assessed by dialysis, which was fitted with suitable mathematical models. Approximately 69.205%±2.5% of the drug was released in 24 hours in medium of pH 1.2, whereas ~78%±2.28% of drug was released in medium of pH 7.4, with floating behavior for ~7.5 hours. The results of in vivo study showed a 3.25-fold increase in bioavailability. Thus, we concluded that CNF aerogels offer a great possibility for a gastroretentive drug delivery system with improved bioavailability.

Citation: Bhandari, J., and Y. Zhang. 2019. Effect of altitude and soil properties on biomass and plant richness in the grasslands of Tibet, China, and Manang District, Nepal.Abstract. A positive relationship between plant species richness and biomass has often documented in temperate grassland systems but is still largely lacking in the Himalayan region. Considering altitude and soil properties as major factors influencing species richness and biomass in the Himalayan grasslands, we tested the hypothesis that peak aboveground biomass and species richness increase with higher levels of soil nutrients and decrease with altitude. Our study was conducted in the grasslands of Tibet, China, and Manang District, Nepal, which represent, respectively, the northern and southern slopes of the central Himalayan grasslands. During the growing seasons, we measured vegetation aboveground biomass and soil properties along an altitudinal gradient on the northern slope in 2011 and 2012, and on the grasslands of the southern slope in 2017. Data were analyzed with a Spearman correlation analysis, classification and regression tree model, and the structural equation modeling (SEM) to identify the key factors determining aboveground biomass and species richness. The results demonstrated that aboveground biomass and species richness on the southern slope were significantly greater at the lowest altitude zone compared to middle and higher zones, whereas on the northern slope, aboveground biomass and species richness were not significantly different at three altitudinal zones. There was a significant positive correlation between aboveground biomass and species richness on both northern and southern slopes. However, the slope was found higher in grasslands of southern slope compared to the grasslands of northern slope. Classification and regression tree analysis and SEM indicated that altitude is most closely associated with large-scale variations in aboveground biomass and species richness. The Spearman correlation analysis revealed that altitude and soil pH were negatively related to aboveground biomass in these grasslands. This study demonstrates that on northern and southern slopes of the Himalayan Range, a positive relation between plant species richness and biomass is determined more by altitude than soil nutrients.

Rain use efficiency (RUE) is an important indicator for identifying the response of plant production to variation in precipitation patterns, especially in semiarid ecosystem grasslands of Inner Mongolia. We have investigated the response and spatial patterns of RUE to precipitation patterns based on five years (2006, 2007, 2008, 2012, and 2013) of records from semiarid ecosystem sites across Inner Mongolia. Our results showed thatRUEADMwas lowest in the wettest year (2012) and highest in the year following the driest year (2008). There was no significant correlation betweenRUEADMandRUETDMin typical and desert steppe.RUETDMwas strongly correlated with both annual precipitation (AP) and growing season precipitation (GSP) compared toRUEADM.RUEADM, therefore, cannot be used in place ofRUETDM.RUEADMincreased with species richness. The relationship betweenRUEADMand species richness was significantly correlated in meadow steppe, typical steppe, and desert steppe. Our findings can shed light on the spatial utilization pattern of seasonal rainfall in semiarid grassland ecosystems.

Climate change has caused uneven changes in hydrological processes (precipitation and evapotranspiration) on a space-temporal scale, which would influence climate types, eventually impact agricultural production. Based on data from 61 meteorological stations from 1961 to 2014 in the North China Plain (NCP), the spatiotemporal characteristics of climate variables, such as humidity index, precipitation, and potential evapotranspiration (ET0), were analyzed. The sensitivity coefficients and contribution rates were applied to ET0. The NCP has experienced a semiarid to humid climate from north to south due to the significant decline of ET0 (−13.8 mm decade−1). In the study region, 71.0% of the sites showed a “pan evaporation paradox” phenomenon. Relative humidity had the most negative influence on ET0, while wind speed, sunshine hours, and air temperature had a positive effect on ET0. Wind speed and sunshine hours contributed the most to the spatiotemporal variation of ET0, followed by relative humidity and air temperature. Overall, the key climate factor impacting ET0 was wind speed decline in the NCP, particularly in Beijing and Tianjin. The crop yield in Shandong and Henan provinces was higher than that in the other regions with a higher humidity index. The lower the humidity index in Hebei province, the lower the crop yield. Therefore, potential water shortages and water conflict should be considered in the future because of spatiotemporal humidity variations in the NCP.