A moment-based criterion for determining the number of components in a normal mixture model

Determining the number of components is a crucial issue in a mixture model. A moment-based criterion is considered to estimate the number of components arising from a normal mixture model. This criterion is derived from an omnibus statistic involving the skewness and kurtosis of each component. The proposed criterion additionally provides a measurement for the model fit in an absolute sense. The performances of our criterion are satisfactory compared with other classical criteria through Monte-Carlo experiments.

The role of organic and inorganic substituents of roxarsone determines its binding behavior and mechanisms onto nano-ferrihydrite colloidal particles

The retention and fate of Roxarsone(ROX)onto typical reactive soil minerals were crucial for evaluating its potential environmental risk.However,the behavior and molecular-level reaction mechanism of ROX and its substituents with iron(hydr)oxides remains unclear.Herein,the binding behavior of ROX on ferrihydrite(Fh)was investigated through batch experiments and in-situ ATR-FTIR techniques.Our results demonstrated that Fh is an effective geo-sorbent for the retention of ROX.The pseudo-second-order kinetic and the Langmuir model successfully described the sorption process.The driving force for the binding of ROX on Fh was ascribed to the chemical adsorption,and the rate-limiting step is simultaneously dominated by intraparticle and film diffusion.Isotherms results revealed that the sorption of ROX onto Fh appeared in uniformly distributed monolayer adsorption sites.The twodimensional correlation spectroscopy and XPS results implied that the nitro,hydroxyl,and arsenate moiety of ROX molecules have participated in binding ROX onto Fh,signifying that the predominated mechanisms were attributed to the hydrogen bonding and surface complexation.Our results can help to better understand the ROX-mineral interactions at the molecular level and lay the foundation for exploring the degradation,transformation,and remediation technologies of ROX and structural analog pollutants in the environment.

Hollow mesoporous silica nanoparticles as nanocarriers employed in cancer therapy: A review

Hollow mesoporous silica nanoparticles(HMSNs)have become an attractive drug carrier because of their unique characteristics including stable physicochemical properties,large specific surface area and facile functionalization,especially made into intelligent drug delivery systems(DDSs)for cancer therapy.HMSNS are employed to transport traditional anti-tumor drugs,which can solve the problems of drugs with instability,poor solubility and lack of recognition,etc.,while significantly improving the anti-tumor effect.And an unexpected good result will be obtained by combining functional molecules and metal species with HMSNs for cancer diagnosis and treatment.Actually,HMSNs-based DDSS have developed relatively mature in recent years.This review briefly describes how to successfully prepare an ordinary HMSNs-based DDS,as well as its degradation,different stimuli-responses,targets and combination therapy.These versatile intelligent nanoparticles show great potential in clinical aspects.

PM2.5 over North China based on MODIS AOD and effect of meteorological elements during 2003-2015

Over the past 40 years,PM2.5 pollution in North China has become increasingly serious and progressively exposes the densely populated areas to pollutants.However,due to limited ground data,it is challenging to estimate accurate PM2.5 exposure levels,further making it unfavorable for the prediction and prevention of PM2.5 pollutions.This paper therefore uses the mixed effect model to estimate daily PM2.5 concentrations of North China between 2003 and 2015 with ground observation data and MODIS AOD satellite data.The tempo-spatial characteristics of PM2.s and the influence of meteorological elements on PM25 is discussed with EOF and canonical correlation analysis respectively.Results show that overall R2 is 0.36 and the root mean squared predicted error was 30.1μg/m^3 for the model prediction.Our time series analysis showed that,the Taihang Mountains acted as a boundary between the high and low pollution areas in North China;while the northern part of Henan Province,the southern part of Hebei Province and the western part of Shandong Province were the most polluted areas.Although,in 2004,2009 and dates after 2013,PM25 concentrations were relatively low.Meteorological/topography conditions,that include high surface humidity of area in the range of 34°-40°N and 119°-124°E,relatively low boundary layer heights,and southerly and easterly winds from the east and north area were common factors attributed to haze in the most polluted area.Overall,the spatial distribution of increasingly concentrated PM2.5 pollution in North China are consistent with the local emission level,unfavorable meteorological conditions and topographic changes.

Cell-penetrating riboflavin conjugate for antitumor photodynamic therapy

Riboflavin(RF,vitamin B2)is an essential vitamin and has been considered as a promising natural photosensitizer for photodynamic therapy(PDT).However,further exploration of RF in antitumor application was limited by its poor cellular uptake.In this study,using cell-penetrating peptides Arg8,(Cha-Arg)3 and small molecule triphenylphosphine(TPP)as delivery compounds,three RF conjugates were prepared to increase the accumulation of RF in cells,termed as Arg8-RF,(Cha-Arg)3-RF and TPP-RF,respectively.Compared with TPP-RF and Arg8-RF,(Cha-Arg)3-RF exhibited better cell internalization and stronger cytotoxicity against HeLa cells upon exposure to blue light.Further researches proved that(Cha-Arg)3-RF generated reactive oxygen species(ROS)under irradiation,which could indiscriminately destroy endogenous proteins and mitochondria,ultimately inducing cell death.This work provides a new approach to explore RF as a natural photosensitizer for antitumor photodynamic therapy.

Picture Quality Assessment-Based on Rate Control for Variable Bandwidth Networks

The growing popularity of Internet applications and services has rendered high subjective video quality crucial to the user experience. Increasing needs for better video resolution and faster transmission bandwidths present challenges to the goal of achieving balance between video quality and coding cost. In this paper, we propose a Perceptive Variable Bit-Rate Control （PVBRC） framework for the state-of-the-art video coding standard High-Efficiency Video Coding （HEVC）/H.265. PVBRC allocates a bit-rate to a picture while taking a Comprehensive Picture Quality Assessment （CPQA） model and perceptive target bit-rate allocation into consideration. The CPQA model calculates the objective and perceptive quality of both source and reconstructed pictures by referring to the human vision system. The coding bit-rate is then dynamically allocated by the result of the CPQA model according to differences in picture content. In PVBRC, the quantization parameter for current picture encoding is updated by an effective fuzzy logical controller to satisfy the transmission requirements of the Internet of Things. Experimental results show that the proposed PVBRC can achieve average bit savings by 11.49% when compared with constant bit-rate control under the same objective and subjective video quality.

A Double-Edged Sword: Russia’s Hybrid Warfare in Syria

Hybrid warfare refers to the use of conventional and unconventional ways and means,by any combination of state and nonstate actors,within the same battle space.Russia has widely employed the concept of hybrid warfare in practice from Ukraine to Syria in the 2010s to advance its interests.The article is presented by solving the following problem:what does Russia’s hybrid warfare in Syria mean to Middle East security issues?The answer to the problem could be obtained by evaluating the theory and practice of Russia’s hybrid warfare.Though the concept of hybrid warfare/hybrid wars was first analysed systematically by Frank Hoffman,an American scholar,in 2007,Russian transformed its methods into a new version to accommodate their specific needs and named it after the Chief of General Staff of the Russian Federation,Witalij Gerasimov.It is necessary to explain the features of Russia’s hybrid warfare theory which helps us assess Russian actions in Syria.And these assessments could show us the efficiency of hybrid warfare.Both the theory and practice of Russia’s hybrid warfare have demonstrated that states may deal with security threats from other state and non-state actors properly by conventional and unconventional ways to keep peace and stability or protect their interests.It may offer us a potential method to eliminate terrorism and extremism in order to save weak or failed states.Yet the aggressiveness of hybrid warfare could also sabotage the vulnerable security structure in the Middle East and cause more conflicts and insurgencies.If so,what should we do to alter the situation?The framework for avoiding the dark side of hybrid warfare is based on international cooperation and assistance to failed states.