Template Route to Chemically Engineering Cavities at Nanoscale: A Case Study of Zn(OH)2 Template

A size-controlled Zn(OH)2 template is used as a case study to explain the chemical strategy that can be executed to chemically engineering various nanoscale cavities. Zn(OH)2 octahedron with 8 vertices and 14 edges is fabricated via a low temperature solution route. The size can be tuned from 1 to 30 μm by changing the reaction conditions. Two methods can be selected for the hollow process without loss of the original shape of Zn(OH)2 template. Ion-replacement reaction is suitable for fabrication of hollow sulfides based on the solubility difference between Zn(OH)2 and products. Controlled chemical deposition is utilized to coat an oxide layer on the surface of Zn(OH)2 template. The abundant hydroxyl groups on Zn(OH)2 afford strong coordination ability with cations and help to the coating of a shell layer. The rudimental Zn(OH)2 core is eliminated with ammonia solution. In addition, ZnO-based heterostructures possessing better chemical or physical properties can also be prepared via this unique templating process. Room-temperature photoluminescence spectra of the heterostructures and hollow structures are also shown to study their optical properties

Analysis of hard X- and gamma-rays and microwave emissions during the flare of July 18, 2002

The Nobeyama Radioheliograph observation results and data from the KONUS-Wind spectrometer mounted at the Wind and RHESSI satellites on several solar flares are jointly analyzed. The analysis results for data on the flare of July 18, 2002 are described. The hard X-rays were measured in the 18 keV-15 MeV range (KONUS-Wind), and spectroheliograph measurements were carried out in the radio range at frequencies of 17 and 34 GHz. Spatial distributions of the radio brightness were calculated for the flare of July 18, 2002; they show the presence of two sources at the footpoints and one source at the top of the supposed flaring loop. The energy spectra of hard X-rays, energy flux, and the total number of accelerated electrons were found from the KONUS spectrometer data. The number of accelerated X-ray emitted electrons was estimated as N a parts per thousand yen 10(36), and the maximum X-ray energy flux was estimated as 5 x 10(-6) erg cm(-2) s(-1). The spectrum index varies in time from -4.6 to -3.6, i.e., the soft-hard-harder trend is implemented. The spectral index of the radio waves is alpha a parts per thousand -0.3 at the flare start, attains the value alpha a parts per thousand -0.5 at the flux maximum, and even change the sign further. The accelerated electron transport model in the flare loop plasma is suggested for interpretation of relationships between parameters of the radio emission and hard X-rays

Water quality trend and change-point analyses using integration of locally weighted polynomial regression and segmented regression

Trend and change-point analyses of water quality time series data have important implications for pollution control and environmental decision-making. This paper developed a new approach to assess trends and change-points of water quality parameters by integrating locally weighted polynomial regression (LWPR) and segmented regression (SegReg). Firstly, LWPR was used to pretreat the original water quality data into a smoothed time series to represent the long-term trend of water quality. Then, SegReg was used to identify the long-term trends and change-points of the smoothed time series. Finally, statistical tests were applied to determine the significance of the long-term trends and change-points. The efficacy of this approach was validated using a 10-year record of total nitrogen (TN) and chemical oxygen demand (CODMn) from Shanxi Reservoir watershed in eastern China. Results showed that this approach was straightforward and reliable for assessment of long-term trends and change-points on irregular water quality datasets. The reliability was verified by statistical tests and practical considerations for Shanxi Reservoir watershed. The newly developed integrated LWPR-SegReg approach is not only limited to the assessment of trends and change-points of water quality parameters but also has a broad application to other fields with long-term time series records

Nonviral Gene Delivery: Principle, Limitations, and Recent Progress

Gene therapy is becoming a promising therapeutic modality for the treatment of genetic and acquired disorders. Nonviral approaches as alternative gene transfer vehicles to the popular viral vectors have received significant attention because of their favorable properties, including lack of immunogenicity, low toxicity, and potential for tissue specificity. Such approaches have been tested in preclinical studies and human clinical trials over the last decade. Although therapeutic benefit has been demonstrated in animal models, gene delivery efficiency of the nonviral approaches remains to be a key obstacle for clinical applications. This review focuses on existing and emerging concepts of chemical and physical methods for delivery of therapeutic nucleic acid molecules in vivo. The emphasis is placed on discussion about problems associated with current nonviral methods and recent efforts toward refinement of nonviral approaches

Non-viral gene delivery strategies for gene therapy: a “ménage à trois” among nucleic acids, materials, and the biological environment

Gene delivery is the science of transferring genetic material into cells by means of a vector to alter cellular function or structure at a molecular level. In this context, a number of nucleic acid-based drugs have been proposed and experimented so far and, as they act on distinct steps along the gene transcription-translation pathway, specific delivery strategies are required to elicit the desired outcome. Cationic lipids and polymers, collectively known as non-viral delivery systems, have thus made their breakthrough in basic and medical research. Albeit they are promising alternatives to viral vectors, their therapeutic application is still rather limited as high transfection efficiencies are normally associated to adverse cytotoxic side effects. In this scenario, drawing inspiration from processes naturally occurring in vivo, major strides forward have been made in the development of more effective materials for gene delivery applications. Specifically, smart vectors sensitive to a variety of physiological stimuli such as cell enzymes, redox status, and pH are substantially changing the landscape of gene delivery by helping to overcome some of the systemic and intracellular barriers that viral vectors naturally evade. Herein, after summarizing the state-of-the-art information regarding the use of nucleic acids as drugs, we review the main bottlenecks still limiting the overall effectiveness of non-viral gene delivery systems. Finally, we provide a critical outline of emerging stimuli-responsive strategies and discuss challenges still existing on the road toward conceiving more efficient and safer multifunctional vectors