Determination of arsenic in airborne particulate matter by inductively coupled plasma mass spectrometry

[[abstract]]An optimized sample digestion procedure was developed for determining As in airborne particulate matter by ICP-MS and applied to real sample analysis. A two-step high-pressure bomb digestion procedure, entailing the digestion of airborne particulates with HNO3-HClO4 and then digestion with HClO3-HF after the removal of the intact filter membrane, appears to be the most effective pre-treatment procedure for determining As by ICP-MS. The direct determination of As in airborne particulate matter by laser ablation ICP-MS was also investigated, Standard filters prepared in the laboratory and real samples were both analyzed, and the results agreed with the certified concentrations and data obtained from the conventional acid digestion-ICP-MS method, Finally, the capabilities of various analytical techniques applied to real sample analysis were compared.[[fileno]]2060217010012[[department]]生醫工程與環境科學

Statistical analysis driven optimized deep learning system for intrusion detection

Attackers have developed ever more sophisticated and intelligent ways to hack information and communication technology systems. The extent of damage an individual hacker can carry out upon infiltrating a system is well understood. A potentially catastrophic scenario can be envisaged where a nation-state intercepting encrypted financial data gets hacked. Thus, intelligent cybersecurity systems have become inevitably important for improved protection against malicious threats. However, as malware attacks continue to dramatically increase in volume and complexity, it has become ever more challenging for traditional analytic tools to detect and mitigate threat. Furthermore, a huge amount of data produced by large networks has made the recognition task even more complicated and challenging. In this work, we propose an innovative statistical analysis driven optimized deep learning system for intrusion detection. The proposed intrusion detection system (IDS) extracts optimized and more correlated features using big data visualization and statistical analysis methods (human-in-the-loop), followed by a deep autoencoder for potential threat detection. Specifically, a pre-processing module eliminates the outliers and converts categorical variables into one-hot-encoded vectors. The feature extraction module discard features with null values and selects the most significant features as input to the deep autoencoder model (trained in a greedy-wise manner). The NSL-KDD dataset from the Canadian Institute for Cybersecurity is used as a benchmark to evaluate the feasibility and effectiveness of the proposed architecture. Simulation results demonstrate the potential of our proposed system and its outperformance as compared to existing state-of-the-art methods and recently published novel approaches. Ongoing work includes further optimization and real-time evaluation of our proposed IDS.Comment: To appear in the 9th International Conference on Brain Inspired Cognitive Systems (BICS 2018

A review of landslide problems and mitigation measures in Chongqing and Hong Kong: Similarities and differences

The cities of Chongqing and Hong Kong are both located at hilly areas which are highly populated, with buildings and major highways located very close to slopes and earth-retaining structures. Landslides and rockfalls are very common in both cities, and large expenditures are being incurred by both Governments on the investigation, design and implementation of mitigation and preventive measures to reduce the likelihood of the loss of life and economic losses due to landslides. As a result of the collaborative studies and technical exchange programs between the University of Hong Kong and the Chongqing Jianzhu University, a more in-depth understanding of the landslide problem, methodology and mitigation measures in Chongqing and Hong Kong was achieved. The objective of this paper is therefore to: (1) highlight the similarities and differences of the slope safety problems which these cities have been facing and (2) present and compare the key technical approaches these two cities have been undertaken to reduce the risk of landslide and rockfalls, so that both cities could benefit from the experience and lesson learnt. Based on the review of literature and published case records, it is concluded that the city of Chongqing has to deal with natural hazards such as earthquake, river erosion and flooding more than that in Hong Kong, but both cities have been applying practical and latest technology to mitigating the landslide problem. It is recommended that the city of Chongqing should consider establishing a sustainable long-term landslide management plan and that the landslide prevention system being used in Hong Kong could be a good reference starting point. © 2004 Elsevier B.V. All rights reserved.postprin

Advances in genetic engineering for plants abiotic stress control

Agricultural productivity is highly influenced by abiotic stresses, known as the most harmful factor concerning the growth and productivity of crops worldwide. Furthermore, industrial crops are nowadays highly influenced by abiotic stress; these include extremes in temperature, drought, salinity, heavy metals and radiation. Typical studies were discussed by many researchers about the control of abiotic stress in plants by the expression, over-expression or switching off abiotic stress-related genes. Despite the rapid evolution of the research, some crops are still expected to decline by 15 to 32% in the next fifty years. Consequently, engineering genes that protect and maintain the function and structure of cellular components can enhance tolerance to stress. This review presents principal methods adapted in the control of plants abiotic stresses including recent advances in using transgenes for the improvement of abiotic stress tolerance in plants. Specified analysis of recent advances in abiotic stress control could describe trehalose as a better compound in the control of plant abiotic stresses. Therefore, studies of genes-related trehalose metabolism and associated patterns could not only provide an improved plant metabolism, phenotypes and texture, but in fact, the plants become highly resistant to abiotic stress.Key words: Abiotic stresses, crops, expression, over-expression, switching off, trehalose, genes-related

The effect of gamma irradiation on the biological properties of intervertebral disc allografts: in vitro and in vivo studies in a beagle model

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Self-catalytic ZnSe nanorods on grains synthesized using thermal evaporation method

In this paper, ZnSe nanorods grown on in-situ synthesized ZnSe grains are reported. The ZnSe products are synthesized through thermal evaporation of elementary materials of Zn and Se powders in a horizontal resistance furnace. It is interesting to note that the ZnSe nanorods of nearly the same diameter and length are obtained, and they grow in the same direction on a facet of the ZnSe grain. The ZnSe grains are random in shape, with well-defined bounded facets. The ZnSe grains can be synthesized in various growth conditions while the ZnSe nanorods can be synthesized on the ZnSe grains with the fulfillment of the Zn enriched condition. The growth of ZnSe nanorods can be described by the self-catalytic vapor-liquid-solid (VLS) mechanism.postprin

Quantification of optical pulsed-plane-wave-shaping by chiral sculptured thin films

The durations and average speeds of ultrashort optical pulses transmitted through chiral sculptured thin films (STFs) were calculated using a finite-difference time-domain algorithm. Chiral STFs are a class of nanoengineered materials whose microstructure comprises parallel helicoidal nanowires grown normal to a substrate. The nanowires are $\sim$10-300 nm in diameter and $\sim1-10 \mu$m in length. Durations of transmitted pulses tend to increase with decreasing (free-space) wavelength of the carrier plane wave, while average speeds tend to increase with increasing wavelength. An increase in nonlinearity, as manifested by an intensity-dependent refractive index in the frequency domain, tends to increase durations of transmitted pulses and decrease average speeds. The circular Bragg phenomenon exhibited by a chiral STFs manifests itself in the frequency domain as high reflectivity for normally incident carrier plane waves whose circular polarization state is matched to the structural handedness of the film and whose wavelength falls in a range known as the Bragg regime; films of the opposite structural handedness reflect such plane waves little. This effect tends to distort the shapes of transmitted pulses with respect to the incident pulses, and such shaping can cause sharp changes in some measures of average speed with respect to carrier wavelength. A local maximum in the variation of one measure of the pulse duration with respect to wavelength is noted and attributed to the circular Bragg phenomenon. Several of these effects are explained via frequency-domain arguments. The presented results serve as a foundation for future theoretical and experimental studies of optical pulse propagation through causal, nonlinear, nonhomogeneous, and anisotropic materials.Comment: To appear in Journal of Modern Optic

Fractional Anisotropy in Corpus Callosum Is Associated with Facilitation of Motor Representation during Ipsilateral Hand Movements

BACKGROUND: Coactivation of primary motor cortex ipsilateral to a unilateral movement (M1(ipsilateral)) has been observed, and the magnitude of activation is influenced by the contracting muscles. It has been suggested that the microstructural integrity of the callosal motor fibers (CMFs) connecting M1 regions may reflect the observed response. However, the association between the structural connectivity of CMFs and functional changes in M1(ipsilateral) remains unclear. The purpose of this study was to investigate the relationship between functional changes within M1(ipsilateral) during unilateral arm or leg movements and the microstructure of the CMFs connecting both homotopic representations (arm or leg). METHODS: Transcranial magnetic stimulation was used to assess changes in motor evoked potentials (MEP) in an arm muscle during unilateral movements compared to rest in fifteen healthy adults. Functional magnetic resonance imaging was then used to identify regions of M1 associated with either arm or leg movements. Diffusion-weighted imaging data was acquired to generate CMFs for arm and leg areas using the areas of activation from the functional imaging as seed masks. Individual values of regional fractional anisotropy (FA) of arm and leg CMFs was then calculated by examining the overlap between CMFs and a standard atlas of corpus callosum. RESULTS: The change in the MEP was significantly larger in the arm movement compared to the leg movement. Additionally, regression analysis revealed that FA in the arm CMFs was positively correlated with the change in MEP during arm movement, whereas a negative correlation was observed during the leg movement. However, there was no significant relationship between FA in the leg CMF and the change in MEP during the movements. CONCLUSIONS: These findings suggest that individual differences in interhemispheric structural connectivity may be used to explain a homologous muscle-dominant effect within M1(ipsilateral) hand representation during unilateral movement with topographical specificity