A novel double-image encryption scheme based on cross-image pixel scrambling in gyrator domains.

Recently, a number of double-image cryptosystems have been developed. However, there are notable security performance differences between the two encryption channels in these algorithms. This weakness downgrades the security level and practicability of these cryptosystems, as the cryptosystems cannot guarantee all the input images be transmitted in the channel with higher security level. In this paper, we propose a novel double-image encryption scheme based on cross-image pixel scrambling in gyrator domains. The two input images are firstly shuffled by the proposed cross-image pixel scrambling approach, which can well balance the pixel distribution across the input images. The two scrambled images will be encoded into the real and imaginary parts of a complex function, and then converted into gyrator domains. An iterative architecture is designed to enhance the security level of the cryptosystem, and the cross-image pixel scrambling operation is performed to the real and imaginary parts of the generated complex encrypted data in each round. Numerical simulation results prove that a satisfactory and balanced security performance can be achieved in both channels.

An improved permutation-diffusion type image cipher with a chaotic orbit perturbing mechanism.

During the past decades, chaos-based permutation-diffusion type image cipher has been widely investigated to meet the increasing demand for real-time secure image transmission over public networks. However, the existing researches almost exclusively focus on the improvements of the permutation and diffusion methods independently, without consideration of cooperation between the two processes. In this paper, an improved permutation-diffusion type image cipher with a chaotic orbit perturbing mechanism is proposed. In the permutation stage, pixels in the plain image are shuffled with a pixel-swapping mechanism, and the pseudorandom locations are generated by chaotic logistic map iteration. Furthermore, a plain pixel related chaotic orbit perturbing mechanism is introduced. As a result, a tiny change in plain image will be spread out during the confusion process, and hence an effective diffusion effect is introduced. By using a reverse direction diffusion method, the introduced diffusion effect will be further diffused to the whole cipher image within one overall encryption round. Simulation results and extensive cryptanalysis justify that the proposed scheme has a satisfactory security with a low computational complexity, which renders it a good candidate for real-time secure image storage and distribution applications.

[A survey report on dermatitis patients in hospital in Baoan district of shenzhen city from 1992 to 2006].

OBJECTIVE: To analyse the epidemiological distribution of dermatitis patients in hospital and provide basis for studying the basic conditions and the prevention of dermatitis especially TCE-induced dermatitis in Baoan District of Shenzhen City. METHODS: All dermatitis patients in hospital in Baoan District from 1992 to 2006 were descriptively analysed. RESULTS: There were 645 dermatitis patients in hospital in Baoan District. The total number of patients is tended to rise in recent years. The main age group of 16 approximately years old, followed by 26 approximately years old, the majority are workers. The clinical diagnosis are allergic dermatitis, drug-induced dermatitis, TCE-induced dermatitis. Compared with other dermatitis, women are more than men in TCE-induced dermatitis (P < 0.05). The risk of hepatic dysfunction in TCE-induced dermatitis was significantly greater than other dermatitis (P < 0.05). It is mainly distributed in electronic, metal, electroplating industry. CONCLUSION: The TCE-induced dermatitis was one of the main occupational hazards in Baoan district. To strengthen self-protection awareness of workers, pay more attention to early work observed and occupational screening in key industries and trades workers, reduce opportunities for occupational exposure, all above can effectively reduce the occurrence of TCE-induced dermatitis.

Impacts of Cd(II) on the conformation and self-aggregation of Alzheimer's tau fragment corresponding to the third repeat of microtubule-binding domain.

Environmental exposure to some heavy metals such as cadmium appears to be a risk factor for Alzheimer's disease (AD), however, definite mechanism of their toxicity in AD remains to be elucidated. Previous studies largely focused on the metal ions binding to beta-amyloid, however, very few papers concerned the interaction between tau and metal ions. For the first time, we investigated the impacts of Cd(II) on the conformation and self-aggregation of Alzheimer's tau peptide R3, corresponding to the third repeat of microtubule-binding domain. The initial state of R3 was proven to be dimeric linked by intermolecular disulfide bond, in the non-reducing buffer (Tris-HCl buffer pH7.5, containing no reducing reagent). In this paper, we show that Cd(II) can accelerate heparin-induced aggregation of R3 or independently induce the aggregation of R3, as monitored by ThS fluorescence. In the presence of Cd(II), the resulting R3 filaments became much smaller, as revealed by electron microscopy. Binding to the Cd(II) ion, the dimeric R3 partially lost its random coil, and converted to alpha-helix structure, as revealed by CD and Raman spectrum. Stoichiometric analysis of CD signal against the ratio of [Cd(II)]/[R3] suggested that the coordination intermediate consisted of two R3 dimers binding to a central cadmium ion. As the seed, the coordination intermediate could extensively accelerate the self-aggregation of R3 via promoting the nucleation step. On the other hand, gain in alpha-helix structure on the peptide chain, by coordinating with Cd(II), could be a critical role to promote self-aggregation, as revealed by Raman spectrum. These results provide a further insight into the mechanism of tau filament formation and emphasize the possible involvement of Cd(II) in the pathogenesis of AD.

[Recent development of speciation analysis for trace arsenic].

The present paper summarizes recent development in the measurements of trace arsenic element, including six aspects such as spectrophotometry, atomic adsorption spectrometry, hydride generation atomic fluorescence spectrometry, inductively coupled plasma-atomic emission spectroscopy, X-ray fluorescence spectrometry, united detection of chromatography-atomic characteristic and so on. The basic characteristics and application fields of each method are introduced. The advantages and disadvantages of different methods are discussed. It is pointed out that great progress has been made for the measurements of trace arsenic element in the past decades, but studies on speciation analysis of trace arsenic are still limited. For various speciation of trace arsenic in nature, how to find and develop various efficient, selective separation and analysis technologies is one of the most important problems to be considered. More attention should be paid to the united application of different modern analysis technologies for trace arsenic.

[Residue Levels and Health Risk Assessment of Organochlorine Pesticides in Rice from Shanghai].

As one of the main producers and consumers of pesticides in the world, China has historically used large quantities of organochlorine pesticides, such as DDT and HCH. Rice is a staple food crop in Shanghai, where the Qingpu and Chongming districts are two important rice planting areas. This study detected the residue levels of 24 organochlorine pesticides (OCPs) in rice samples collected from Qingpu and Chongming in Shanghai. The composition and health risk of OCPs in rice samples were investigated. The results revealed that DDTs and HCHs were the main OCPs in rice from the study area. The mean levels of 24 OCPs residues in rice from Qingpu and Chongming were 6.53 ng·g-1 and 4.70 ng·g-1, respectively. The analyses of all the target compounds met the China National Food Safety Standard. The concentrations of 4,4-DDE and ß-HCH were the highest in rice from Qingpu, while 2,4-DDT and ß-HCH were the main components in rice from Chongming. Source analysis showed that dicofol and lindane might be still used recently in some areas of Shanghai. The health risk assessment results indicated that there was no obvious risk to human health by eating rice from Shanghai based on the OCPs studied.

Removal of cadmium using MnO2 loaded D301 resin.

MnO2 loaded weak basic anion exchange resin D301 (Anion exchange resin, macroreticular weak basic styrene) as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd2+ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. T he saturate adsorption capacity of the Cd2+ was 77.88 mg/g. Theadsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.

[Separation of Cr( VI) and organic Cr(III) in natural water by weak basic anion exchange resin and determination by ICP-AES].

For the separation and determination of inorganic Cr(VI) and organic Cr(III) in natural water, a sensitive and selective method was developed using a weak basic anion exchange resin micro-column and inductively coupled plasma atomic emission spectrometry (ICP-AES). Under optimized conditions, organic Cr(III) and inorganic Cr( VI) were retained on the column, and eluted with 1. 0 mol x L(-1) HCl and 2. 0 mol x L(-1) NH4 NO3 +0. 5 mol x L(-1) NH3 x H2O respectively. Then the concentrations of Cr(VI) and organic Cr(III) were determined by ICP-AES. The detection limits of organic Cr( III ) and inorganic Cr(VI) were 1. 1 and 1. 4 microg x L(-1) , and relative standard deviations(RSD) were 3. 8% and 5. 6% respectively. The proposed method has been applied to the determination and separation of chromium in several practical water samples with a recovery between 90. 4% and 106. 3%.

Historical development and future perspectives of Environmental Specimen Bank in China: a mini review.

Environmental problems as well as their related ecosystem stress and human health risk in China have raised wide concerns along with the rapid economic development in recent years. Numerous studies with a sharp increase in publication number have addressed the ubiquitous of anthropogenic chemicals in various environmental compartments and human tissues. However, very few data were available to clarify the temporal trend and to give the retrospective analysis of chemical pollution in China. Environmental Specimen Bank (ESB) is a system for the systematic collection and long-term storage of specimens, which has been established since the 1970s in developed counties and recognized as a fundamental complement for environmental monitoring and scientific research. Currently, the value of ESB is becoming more broadly recognized globally, and China is still at the early stage. This article described the history and status and put forwarded the future key points of Chinese ESB development for illustrating the intensive environmental changes in China and the world.

[The study of adsorption of L-aspartic acid on silver sol by surface-enhanced Raman scattering].

The adsorption state and the characteristics of L-aspartic acid adsorbed on silver sol were studied by the Surface-Enhanced Raman Scattering (SERS) method. Strong Raman signals were detected in the experiments. The results suggested that L-aspartic acid adsorbed on the silver surfaces through carboxyl and nitrogen atoms since the signals were mainly due to the carboxyl and the nitrogen of the molecule of L-aspartic acid. The adsorption of carboxyl on the silver surfaces is chemical adsorption, which is based on the mechanism of charge-transfer, while the adsorption of nitrogen on the silver surfaces is physical type, which is due to the electromagnetic mechanism. The intensity of surface-enhanced Raman scattering of L-aspartic acid adsorbed on silver surface was also analyzed, and it was found that the intensity of surface-enhance Raman scattering will change with different concentrations of L-aspartic acid adsorbed on the silver surfaces. The intensity will reach the top value when the concentration of L-aspartic acid was 10(-3) mol x L(-1). When the concentration of L-aspartic acid decreased to 10(-4) mol x L(-1), the intensity of surface-enhanced Raman scattering became a little weaker than that with 10(-3) mol x L(-1). With further decrease in the concentration of L-aspartic acid, the intensity of surface-enhanced Raman scattering also decreased gradually. When the concentration of L-aspartic acid decreased to 10(-6) mol x L(-1), the intensity of surface-enhanced Raman scattering was very low. The above study will be helpful to the further study of peptide and other complex biological systems.

An efficient and secure medical image protection scheme based on chaotic maps.

Recently, the increasing demand for telemedicine services has raised interest in the use of medical image protection technology. Conventional block ciphers are poorly suited to image protection due to the size of image data and increasing demand for real-time teleradiology and other online telehealth applications. To meet this challenge, this paper presents a novel chaos-based medical image encryption scheme. To address the efficiency problem encountered by many existing permutation-substitution type image ciphers, the proposed scheme introduces a substitution mechanism in the permutation process through a bit-level shuffling algorithm. As the pixel value mixing effect is contributed by both the improved permutation process and the original substitution process, the same level of security can be achieved in a fewer number of overall rounds. The results indicate that the proposed approach provides an efficient method for real-time secure medical image transmission over public networks.

[Measurement and preliminary human health risk assessment of representative organochlorines in farmed Mandarin fish].

Concentrations of representative organochlorines (OCs), including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in a batch of farmed mandarin fish from a cultivation pond in Wujiang City, Jiangsu Province, were determined with GC-ECD. Meanwhile, a preliminary human health risk assessment was conducted. Results showed that, the concentrations of dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and PCBs in the farmed mandarin fish were in the range of 1.3-4.57 ng/g, 0.13-1.24 ng/g, 0.07-0.44 ng/g and 0-5.22 ng/g, respectively, with an average value of 2.96, 0.40, 1.27 and 0.7 ng/g, respectively. These values were far below the corresponding residue limits set by China's Ministry of Health and the U.S. Food and Drug Administration, and at the low end of the global pollution bar. Referring to the reference values given by USEPA Integrated Risk Information System, calculated non-carcinogenic hazard ratios (HRs) of DDTs, HCB and PCBs were all <1 and carcinogenic HRs of DDTs, HCHs, HCB and PCBs were all >1. The results indicated that DDTs, HCHs and HCB in farmed mandarin fish did not have negative human health influence, but existed potential carcinogenic risk to humans. Compared to rural residents, urban residents were more vulnerable to DDTs, HCHs, HCB and PCBs threats.

[Adsorption of fluoride ions on a Ca-deficient hydroxyapatite].

A Ca-deficient hydroxyapatite (d-HAp) from the by-product of phosphate wastewater treatment has been used to remove fluoride ions. The effects of pH, coexistent calcium and magnesium ions, and chloride ions on the adsorption efficiency were investigated for the system. The results showed that d-HAp adsorbed F- efficiently within a wide pH range (4-7), and the defluoridation capacity of d-HAp remained 85%. There was no significant effect on removal of fluoride ions with addition of up to 200 times as high a concentration of Ca2+, Mg2+ and Cl-, so it suggested that d-HAp was applicable to high fluoride area. The adsorption kinetics can be described by Pseudo-second-order reaction model and the correlation coefficient R2 was 0.999 0. It was also found that the adsorption of F- on d-HAp followed the Langmuir model. The maximal static adsorption capacity was calculated as 26.11 mg x g(-1). It also suggested that ion exchange was the main mechanism during this adsorptive process.

[Kinetics of monochloramine decay in disinfection of drinking water].

The model of second-order reaction kinetics has been used to fit the monochloramine decay in water samples by nonlinear imitation. Several factors were investigated, including pH, temperature, carbonate, bromide, iodide concentrations and natural organic matters in this system. The results showed that pH value was an important factor on the monochloramine decay rate, especially when pH was below 7.0. Temperature and carbonate levels also had obvious effect on the monochloramine decay. Co-existence of bromide anions had different impact under different pH values. At pH 6.60, monochloramine decay rate tended to decrease dramatically with the increment of bromide levels. However, when pH was above 7.60, 0.1 mg/L of bromide hardly affected the decay rate of mononchloramine. Co-existence of iodide showed stronger effect on the decline rate of monochloramine than that of bromide. It was demonstrated that the second-order kinetic model could fit well the experimental results of monochloramine decay reaction under the conditions of bromide or iodide co-existence. The results of this study will be of benefit to the theory and technology of drinking water disinfection, especially for the reduction of DBPs and the control of disinfectant dosages in the area of coastland and estuary.

[Influencing factors of calcite active barrier system to control phosphorus release from sediments].

Influencing factors of calcite active barrier system to control phosphorus release from sediments were researched, including barrier thickness, Ca2+ of overlying water, temperature, calcite's grain size and artificial aeration. The results show that the calcite barrier can effectively control phosphorus release from sediments under anaerobic conditions, and its efficiency was influenced by barrier thickness, Ca2+ concentration of overlying water, temperature, calcite's grain size and artificial aeration. The efficiency of calcite barrier to control phosphorus release from sediments will increase with the increment of Ca2+ concentration of overlying water and barrier thickness. Application of 12.7 kg/m2 calcite active barrier system resulted in 56% reduction of phosphorus flux from sediment for 72 days; however 99% reduction was obtained by 38.2 kg/m2 calcite active barrier system. When the Ca2+ concentration of overlying water increased from 1 mmol/L to 5 mmol/L, the phosphorus concentration was reduced by about 36% in the 72nd day. In comparison to low temperature, high temperature was disbennifit to control phosphorus release from sediments by a thin calcite barrier. The smaller the grain sizes of calcite, the more efficient the calcite barrier. The ammonia and phosphorus release rate from sediments under calcite barrier will be decreased by aeration.