We report the control of guest release profiles by dialing-in desirable interactions between guest molecules and pores in metal–organic frameworks (MOFs). The interactions can be derived by the rate ...constants that were quantitatively correlated with the type of functional group and its proportion in the porous structure; thus the release of guest molecules can be predicted and programmed. Specifically, three probe molecules (ibuprofen, rhodamine B, and doxorubicin) were studied in a series of robust and mesoporous MOFs with multiple functional groups MIL-101(Fe)-(NH2) x , MIL-101(Fe)-(C4H4) x , and MIL-101(Fe)-(C4H4) x (NH2)1–x . The release rate can be adjusted by 32-fold rhodamine from MIL-101(Fe)-(NH2) x , and the time of release peak can be shifted by up to 12 days over a 40-day release period doxorubicin from MIL-101(Fe)-(C4H4) x (NH2)1–x , which was not obtained in the physical mixture of the single component MOF counterparts nor in other porous materials. The corelease of two pro-drug molecules (ibuprofen and doxorubicin) was also achieved.
•A landslide sediment supply capacity assessment model was developed for applications in debris flow basins.•Spatial and temporal variability of landslide sediment supply capacity is ...significant.•Decay of landslide sediment supply capacity to the pre-earthquake level is expected within 17 years.•The evolution of landslide activity has a positive effect on the landslide sediment transport capacity.
After the Wenchuan earthquake, a large number of landslides in debris flow basins continued to provide loose debris for channels and further affected the occurrence of debris flows. Evaluating the landslide sediment supply capacity in debris flow basins requires understanding the landslide activity and the coupled relationship between the landslide and the channel. In this study, we proposed a model based on the landslide area density index (PAls) and the landslide connectivity (ICl) to evaluate the capacity of the landslide sediment supply for channels in 46 sub-catchments in the study area. The capacity of the landslide sediment supply for channels generally decreased from 2008 to 2018, but due to the influence of heavy rainfall, the actual capacity of the landslide sediment supply for channels in the study area may gradually diminish in an unstable way, and it may arrive at the pre-earthquake level by 2025 without the influence of extreme rainfall. However, higher debris flow activity may last longer than 2025 because sufficient gully materials are still accumulated in the channel. The sediment transport capacity of landslides was divided into five levels: extremely, high, moderate, slight and low. The capacity of the landslide sediment supply for channels changed from extreme levels and high levels to moderate levels and slight levels after the first 5 years of the Wenchuan earthquake and was then dominated by low levels. Simultaneously, the regions with higher landslide sediment supply capacities gradually changed from along the Minjiang River regions to the upper and middle reaches of the debris flow basin from 2008 to 2018. Hongchun gully, which is in the study area, was chosen as an example to compare the assessment results and field investigation. The long-term evolution of landslides is an important reason for the decrease in the sediment supply capacity of landslides.
Quaternized celluloses (QCs) were homogeneously synthesized by reacting cellulose with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) in NaOH/urea aqueous solutions. The structure and ...solution properties of the QCs were characterized by using elemental analysis, FTIR, 13C NMR, SEC-LLS, viscometer, and ζ-potential measurement. The results revealed that water-soluble QCs, with a degree of substitution (DS) value of 0.20−0.63, could be obtained by adjusting the molar ratio of CHPTAC to anhydroglucose unit (AGU) of cellulose and the reaction time. The QC solutions in water displayed a typical polyelectrolyte behavior, and the intrinsic viscosity (η) value determined from the Fuoss−Strauss method increased with increasing DS value. Moreover, two QC samples (DS = 0.46 and 0.63) were selected and studied as gene carriers. The results of gel retardation assay suggested that QCs could condense DNA efficiently. QCs displayed relatively lower cytotoxicity as compared with PEI, and QC/DNA complexes exhibited effective transfection compared to the naked DNA in 293T cells. The quaternized cellulose derivatives prepared in NaOH/urea aqueous solutions could be considered as promising nonviral gene carriers.
Catastrophic debris flows are frequently triggered by rainstorms after the 2008 Wenchuan earthquake and pose great threats to residential buildings and human lives in the mountainous areas. However, ...little effort has been devoted to studying the quantitative assessment of the physical vulnerability of buildings to debris flows in the Wenchuan earthquake-affected areas. To cope with this deficiency, this paper presented a quantitative method to assess the physical fragility of buildings related to debris flows by analyzing the debris flow activity and building damage features. First, we constructed a building database in the area affected by the Cutou debris flow and determined the degree of damage to each building. Then, the momentum flux was selected as a debris flow intensity parameter, considering the combined effect of flow velocity and flow depth. We used the FLO-2D software to reproduce the process of the debris flow that occurred on 20 August 2019 in the Cutou gully and obtained the intensity parameters of the debris flow. Finally, we proposed physical fragility curves for different types of building structures to the debris flow based on the model describing the probability of exceeding different damage states corresponding to different intensities of debris flows. In the case of brick-concrete buildings, when the momentum flux was 8 m3/s2, buildings were moderately damaged at the probability P = 1 with a 95% confidence interval, and complete damage was sustained from a momentum flux of 36 m3/s2. Masonry-wood buildings sustained complete damage from a momentum flux of 5 m3/s2. The structural resistance of buildings to debris flows in the Wenchuan earthquake-affected region can be assessed by using the proposed physical fragility functions, which provide a scientific basis for risk management and mitigation strategies.
•We constructed the building database and analyzed damage characteristics.•The intensity process of the debris flow was reproduced by FLO-2D software.•The fragility curves were developed by numerical simulation and the probability model.•Masonry-wood buildings will sustain complete damage from the momentum flux of 5 m3/s2.•Brick-concrete buildings will sustain complete damage from the momentum flux of 36 m3/s2.
On August 20, 2019, at 2 a.m., a disastrous debris flow occurred in Chediguan gully in Yinxing town, China. The debris flow destroyed the drainage groove and the bridge at the exit of the gully. In ...addition, the debris flow temporarily blocked the Minjiang River during the flood peak, flooding the Taipingyi hydropower station 200 m upstream and leaving two plant workers missing. To further understand the activity of the debris flow after the Wenchuan earthquake, the characteristics of this debris flow event were studied. Eleven years after the Wenchuan earthquake, a disastrous debris flow still occurred in the Chediguan catchment, causing more severe losses than those of earlier debris flows. In this paper, the formation mechanism and dynamic characteristics of this debris flow event are analysed based on a drone survey, high-definition remote sensing interpretations and other means. The catastrophic debris flow event indicates that debris flows in the Wenchuan earthquake area are still active. A large amount of dredging work in the main gully could effectively reduce the debris flow risk in the gully. In addition, it is also important to repair or rebuild damaged mitigation measures and to establish a real-time monitoring and early warning system for the high-risk gully.
A novel self-delivered prodrug system was fabricated for tumor-targeting therapy. In this nanosystem, the Arg-Gly-Asp-Ser （RGDS） tetrapeptide was used to improve the therapeutic index to ...integrin-overexpressing tumor cells. The antitumorous drug camptothecin was further appended to the ε-amino group of lysine by 20-O-succinyl linkage and controllably released via hydrolytic cleavage. Prodrug molecules self-assembled into fibrillar nano-architectures and achieved the capability of self-delivery after being injected subcutaneously into mice. Introduction of hydrophobic myristic add favored the self-assembly and enhanced the cellular internalization of the prodrugs. In vitro and in vivo studies demonstrated that the self-assembled nanofibers could effectively target integrin- overexpressing tumorous cells and inhibit tumor growth via RGD-mediated specific targeting. Therefore, the traditional idea that fibrillar structures hold low therapeutic efficacy due to poor cell uptake can be challenged.
In recent years, bat-associated pathogens, such as 2019 novel coronavirus, have been ravaging the world, and ectoparasites of bats have received increasing attention. Penicillidia jenynsii is a ...member of the family Nycteribiidae which is a group of specialized ectoparasites of bats. In this study, the complete mitochondrial genome of P. jenynsii was sequenced for the first time and a comprehensive phylogenetic analysis of the superfamily Hippoboscoidea was conducted. The complete mitochondrial genome of P. jenynsii is 16 165 base pairs (bp) in size, including 13 protein-coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes and 1 control region. The phylogenetic analysis based on 13 PCGs of the superfamily Hippoboscoidea known from the NCBI supported the monophyly of the family Nycteribiidae, and the family Nycteribiidae was a sister group with the family Streblidae. This study not only provided molecular data for the identification of P. jenynsii, but also provided a reference for the phylogenetic analysis of the superfamily Hippoboscoidea.
•The first decadal time series analysis is carried out after the 2008 Ms 8.0 Wenchuan earthquake.•Field investigations and experimental approaches evaluate landslide sediment transfer processes along ...hillslopes.•The decadal dynamic transfer process of landslide sediment in the channel was quantified.•The landslide sediment transfer process may last 20–50 years or longer to return to the pre-earthquake level.
The Wenchuan earthquake and subsequent strong rainfall triggered extensive mass wasting, which caused sufficient landslide sediment to be continuously transferred out of the alpine basin. Effective sediment management in earthquake areas requires a full understanding of how landslide sediment is transferred out of alpine basins. In this study, field investigations and remote sensing interpretations indicated that the bedrock or hillslope surface materials were transferred downstream of the hillslope through falls, slides, fall slides, slide falls, and slide flows. Subsequently, field investigations and box model tests showed that the loose landslide sediment was transferred to the channel mainly through three typical processes (erosion driven by torrents or debris flow, saturation, and surface runoff), which occurred simultaneously in the first several years after the Wenchuan earthquake. However, surface runoff erosion was the main transfer process in the following period. Using the number and area of effective landslides, the length and area of landslide sediment in channels, and the effective basin as indicators, we present observational evidence of the landslide sediment transport process based on a remote sensing image time series from 2005 to 2018. The trends of the indicators suggested that the sediment transfer process in the alpine basin was intense during the first 5 years after the Wenchuan earthquake; then, it gradually weakened without the influence of extreme rainfall, but it may last 20 years or longer before returning to the pre-earthquake level.
PDF
