This paper first presents the basic concepts of random graph theory, including undirected, directed, and generalized random graphs. A random homomorphic number mapping is introduced to solve the cut ...distance problem of directed random graphs, and a minimum cut distance is proposed. Next, a virtual machine deployment strategy (VMDS) based on the minimum cut algorithm is proposed to construct VM clusters based on similarity and to cut VM clusters based on the minimum cut of directed random graphs. According to the results, the MAE (1.3875) and MSE (2.7783) of both the conventional AR algorithm and ES algorithm are the lowest. Compared to the MAE (1.7381) and MSE (3.7840) of the VMDS algorithm, both significantly decrease. The research results presented in this paper are useful for applying virtual machine deployment techniques in cloud computing.
Display omitted
•Microplastic-nanoparticle interaction is investigated for the first time.•AgNPs can be captured on the surface of polystyrene microplastics.•AgNPs are more easily captured by ...polystyrene microplastics at lower mass ratios.•Polystyrene microplastics can act as vectors for AgNPs in aquatic environments.•A new pathway for AgNPs to enter organisms is disclosed.
Microplastics and silver nanoparticles (AgNPs) are considered two emerging environmental contaminants that have adverse effects on aquatic environments. Knowledge on the interactions between AgNPs and microplastics may improve our understanding of these pollutants, posing to surrounding environments and public health. However, current knowledge regarding this issue is limited. Here, we investigate, for the first time, the interactions between AgNPs and the microplastics polyethylene (PE), polypropylene (PP), and polystyrene (PS) in aquatic environments. Results showed no significant interactions between AgNPs and PE or PP microplastics. However, AgNPs were efficiently removed by PS microplastics. These differences are mainly attributed to the presence of π-π interactions. Meanwhile, AgNPs aggregations were generated due to higher concentrations of leaching additives derived from PS microplastics. Interestingly, AgNPs are significantly captured on PS microplastic surfaces in the form of Ag0 rather than Ag+. The capture process is a monolayer adsorption and influenced greatly by the mass ratio of AgNPs and PS microplastics. These observations may provide a novel environmental fate of AgNPs, and indicate a new potential method for their removal to some degree. These findings demonstrate the complexities of AgNPs absorption onto microplastics and enhance present understanding of interactions between nanoparticles and microplastics in aquatic environments.
Multifunctional nanoplatforms with multimodal imaging and cancer therapy capabilities have attracted attention in biomedical applications. Near-infrared persistent luminescence nanoparticles (NPLNPs) ...were considered one of the most promising candidates for constructing multifunctional nanoplatforms due to the absence of in situ excitation and high signal-to-noise ratios (SNRs). Here, we report a novel NPLNP mSiO2@Gd3Ga5O12:Cr3+, Nd3+ (mSiO2@GGO) as multifunctional nanoplatforms for multimodal imaging and cancer therapy. These NPs exhibited a persistent luminescence (745 nm) of more than 3 h in the first near-infrared window (NIR-I) after UV excitation, which can realize high SNRs and long-term in vivo imaging. Moreover, these NPs showed excellent NIR luminescence (1067 nm) in the second near-infrared window (NIR-II) under 808 nm excitation, which is more suitable for deep tissue imaging due to the lower photon scattering and deeper tissue penetration of NIR-II luminescence. Furthermore, the host Gd3Ga5O12 with high Gd3+ concentration showed a high r1 value (10.70 mM−1 s−1) and was suitable for T1 MR imaging. The mesoporous silica nanoparticles (mSiO2) served as a framework to control the mSiO2@GGO particle morphology and provide low toxicity and drug loading capacity for cancer therapy.
Display omitted
Abstract In this paper, near infrared-emitting long-persistence luminescent porous Zn1.1 Ga1.8 Ge0.1 O4 :Cr3+ , Eu3+ @SiO2 nanoprobes have been prepared using mesoporous silica nanospheres both as ...morphology-controlling templates and as vessels. These nanoprobes possessed an excellent capacity for drug delivery and allowed for real-time monitoring of the delivery routes of the drug carriers in vivo . The nanoprobes demonstrated a typical mesoporous structure, a brighter NIR emission (696 nm) and a long afterglow luminescence that persisted for 15 d. Furthermore, after surface modification with folic acid (FA), a tumor-targeting group, these nanoprobes exhibited an excellent ability to target tumors with high sensitivity in vitro and in vivo . Importantly, these modified nanoprobes could accurately diagnose tumors and allow for long-term tumor monitoring via in situ and in vivo re-excitation by a red LED lamp. Furthermore, the drug release data demonstrated that the modified nanoprobes could be loaded with a large amount of doxorubicin hydrochloride (DOX) and showed sustained release behavior. Together, the results of this study indicate that these nanoprobes can accurately diagnose tumors, allow for long-term in vivo and in situ monitoring and release DOX in situ to cure tumors.
Recently, Gd3+-based NIR persistent luminescence nanoparticles have been proposed as highly promising multimodal nanoprobes for full-scale visualization medical techniques in early diagnosis of ...cancer. However, they still face with some problems, such as hampering further functionalization for the loss of available surface, shortening plasma half-life of the probe caused by inevitable size increase, and reducing SNR because of significant persistent intensity loss. In this study, a novel core–shell structure Gd3+-based NIR persistent luminescence multimodal probe ZGOCS@MSNs@Gd2O3 for T1-weighted MR imaging and NIR persistent luminescence imaging was successfully synthesized using MSNs as the reaction vessels for ZGOCS nanoparticles and the core for Gd2O3 shell. Compared with previously reported Gd3+-based NIR persistent luminescence-based multimodal nanoprobes, the as-prepared nanoparticles enable surface available, no persistent intensity loss and only a slight size increase. Moreover, this multifunctional nanoprobe not only retains excellent NIR persistent luminescence properties with rechargeable ability, but also possesses high longitudinal relaxivity via the Gd2O3 shell, positioning ZGOCS@MSNs@Gd2O3 as highly promising nanoprobe for future multimodal bioimaging.
Since household carbon emissions (HCEs) have become a new growing source and a significant contributor to global emissions, the reduction of HCEs is crucial. To formulate targeted and effective ...emission mitigation policies, we need to fully understand the characteristics of the distribution and evolution of per capita HCEs and their urban-rural and regional heterogeneity. This paper explores the transitional dynamics of per capita HCEs in China by employing the distribution dynamics approach with panel data compiled at the household level. We find that the overall per capita HCEs are unimodal distribution in the long run and the distribution dynamics of the per capita HCEs between the urban and rural areas or among the regional subgroups are quite different. However, the speed of convergence has accelerated over time. Moreover, our findings indicate that the per capita HCEs in the urban areas will achieve convergence to an emission level much higher than that of the rural areas. Meantime the per capita HCEs in Northeast China will converge to an emission level much higher than those of the other three regions. These findings provide valuable insights for policymakers in implementing differentiated environmental policies for different regions and between urban and rural households in China.
•Distribution dynamics approach is used to investigate per capita carbon emissions at the household level.•Significantly different dynamics can be found for the urban and rural subgroups.•Disparity in carbon emissions is very different among the regions across time.•Single modality convergence can be reached in the long run.
The significant achievements in economic growth and urbanization in China have recently led to substantial increases of and great inequality in household carbon footprints (HCFs). To achieve ...efficiency and justice in emissions reduction, policymakers need to fully understand the sources of HCFs and identify the major causes of carbon inequality. By applying the Unconditional Quantile Regression (UQR) model and decomposition method to the Chinese household survey data, this paper investigates the distributional features of HCFs and their determinants. We find that HCFs are unevenly distributed due to differences in the volume and pattern of consumption, which are further determined by household characteristics and lifestyles. The intertemporal lifestyle changes have played a major role in the rise of HCFs inequality measured by various quantile emissions differentials. In addition, considerable increases in HCFs come from the high carbon emission groups, and most of the HCFs inequality stems from the 90–50 emissions differential. To transform the current carbon-intensive economy, policies are required to enhance environmental equity and encourage low-carbon lifestyles.
•Unconditional quantile regression is used to investigate the distributional features of HCFs.•HCFs are unequally distributed due to differences in the scale and pattern of consumption.•Intertemporal lifestyle changes account for a major part of the rise of HCFs inequality.•Policies are needed to enhance environmental equity and encourage low-carbon lifestyles.
Here, a novel super‐long, ultraviolet A region (UVA), persistent luminescent (PerL) material, LiYGeO4:Bi3+, is developed. After irradiation at 254 nm for 10 min, the UVA PerL of LiYGeO4:Bi3+ can ...persist for more than 300 h. In addition, the LiYGeO4:Bi3+ also possesses a strong UVA emission with a power density of 11.83 mW m−2 at 10 s after the removal of the excitation source. Even after 72 h, the UVA PerL emission spectrum can still be clearly detected, which is the same as the photoluminescence emission spectrum and originated from the Bi3+ emitting centers. Furthermore, LiYGeO4:Bi3+ also exhibits a photostimulated PerL property, which can be easily activated with a red light emitting diode (LED) or NIR laser irradiation after the long‐term decay. Combining the results of the PerL excitation, absorption, and thermoluminescence spectra, the excellent UVA PerL of LiYGeO4:Bi3+ can be ascribed to the existence of abundant trap sites created by the loss of Li+. This excellent PerL material can make up for deficiency of PerL materials in the UVA region and greatly expand the application of PerL materials in the biomedical, energy, environmental, and catalysis fields.
A novel super‐long ultraviolet A region (UVA) persistent luminescent (PerL) material, LiYGeO4:Bi3+, is developed, which exhibits a strong UVA PerL peaking at 350 nm and possesses a super‐long UVA PerL time of more than 300 h. Furthermore, LiYGeO4:Bi3+ simultaneously exhibits an excellent photostimulated UVA PerL capability after a short‐term illumination with red or near‐infrared light.
The particle size distribution of bed materials in the sandy river bed of alluvial rivers is important in the study of topics such as friction, river bed evolution, erosion, and siltation. It also ...can reflect the dependency relation between river bed sediment and flow intensity. In this paper, the critical pattern of sediment movement in the near-wall region of a sandy river bed was analyzed. According to the principle of momentum balance, the critical settling-rising condition of bed material in a sandy river bed was found to be instantaneous turbulent velocity equal to 2.7 times the sediment settling velocity in quiescent water. Based on a vertical instantaneous turbulent velocity with a Gaussian distribution, a theoretical relation for calculating the particle size distribution of bed materials in a sandy river bed without pre-known characteristic grain sizes was developed by solving a stochastic equation. The formula is verified using measured data, and the results show that the proposed formula was in accordance with the measured data. This study has theoretical significance and practical value for determining the bed material particle size distribution of the sandy bed of alluvial rivers.
