Transition metal dichalcogenide coated gold nanoshells for highly effective photothermal therapy.

Transition metal dichalcogenides (TMD) coated gold nanoshells (GNSs), in addition to having low cytotoxicity and a biocompatibility value greater than graphene, exhibit strong light absorption in the near-infrared (NIR) region and high photothermal conversion efficiency. Using a quasi-static approach and bioheat equations, the optical and photothermal properties of GNSs coated with various TMDs are studied for treatment of skin cancer. Our findings show that the intensity of localized surface plasmon resonance (LSPR) peaks and their position in the extinction spectrum of nanoparticles (NPs) can be easily tuned within biological windows by varying the core radius, the gold shell thickness and the number of coating layers of the different TMDs. In order to engineer heat production at designated spatial locations of NPs, near electric field (NEF) enhancement is investigated. Moreover, the effect of laser intensity and the number of TMD layers on the temperature rise and the amount of thermal damage in skin tumor tissue and its surroundings are studied. Our results introduce GNSs with various TMD coatings as superlative nanoagents for photothermal therapy (PTT) applications.

Perception on aggregation induced multicolor emission and emission centers in carbon nanodots using successive dilution, anion exchange chromatography, and multi-way statistics.

Exploration in the way of understanding the optical behavior and structure of carbon nanodots has been increased due to their vast application. Their emission dependency on excitation wavelengths is the more prevalent and controversial subject. In this report we considered the optical structure of hydrothermally synthesized carbon nanodots using citric acid and 2,3-diaminopyridine as precursors. The presence of different emission centers experimented through anion exchange chromatography which resulted in fractions with more unique optical structures. The quantum confinement effect and energy exchange between different types of carbon nanodots, due to aggregation in higher concentration levels, was studied applying a stepwise dilution experiment. Analysis of the experimental data was done through the parallel factor analysis and the trajectory pattern recognition which resolved more about optical interactions and the presence of different emission centers in different particles. Results from infrared spectroscopy confirmed the dominating density of carboxyl functional groups on the nanodots with negative surface charges and higher influence of amine groups on dots with positive surface charges.

Comparison of Mycobacterium avium subsp. paratuberculosis infection in cattle, sheep and goats in the Khuzestan Province of Iran: Results of a preliminary survey.

BACKGROUND: Paratuberculosis or Johne's disease, the chronic infectious granulomatous enteritis of ruminants, is a worldwide infection, which is caused by Mycobacterium avium subsp. paratuberculosis (MAP). The most common symptoms of this disease in cattle are loss of milk production, weight loss and diarrhoea, whereas in sheep and goats, the symptoms are emaciation, anorexia and severe disability. OBJECTIVES: The aim of this study was to compare the seroprevalence of MAP in cattle, sheep and goats in the southwest of Iran. METHODS: Blood samples were randomly collected from 530 cattle, 568 sheep and 368 goats in southwest of Iran. Sera were tested by a commercial ELISA kit (ID vet; ID Screen® Paratuberculosis Indirect) for detection of antibodies of MAP. RESULTS: Overall apparent and true seroprevalence rate of MAP was 6.00% (95% CI: 4.90%-7.30%) and 13.25% (95% CI: 11.55%- 14.95%). Apparent and true seroprevalence of MAP, respectively, was 4.34% (95% CI: 3.88%-6.46%) and 9.19% (95% CI: 6.98%-11.98%) in cattle, 6.87% (95% CI: 5.05%-9.27%) and 15.37% (95% CI: 12.60%-16.60%) in sheep and 7.07% (95% CI: 4.82%-10.18%) and 15.86% (95% CI: 12.41%-20.01%) in goats, respectively. As a result, there was no significant relationship between animal species and MAP infection. Moreover, multivariate logistic regression showed that the infection rate is not associated with age, gender and geographical location in cattle, sheep and goats (P > 0.05). CONCLUSION: This study confirms that the seroprevalence of MAP is relatively considerable in the cattle, sheep and goats in the southwest of Iran, although in cattle, it is less than goats and sheep. Therefore, preventive and control measures should be considered by animal health authorities and meat and dairy processing units.

Optimal mixed control of Axial Flux Permanent Magnet Synchronous generator wind turbines with modular stator structure.

Wind turbine systems are constructed using different types of generators, aero-mechanical components and control systems. Due to their ability to work in low speed, Axial Flux Permanent Magnet (AFPM) generators are becoming widespread in wind energy systems which contributes to eliminating the gearbox from the system, noticeable increase in efficiency and decrease in system weight. Due to the modular nature of the stator in AFPM generators, it is possible to control each module independently. In this paper, in addition to obtain the dynamic model of the turbine and AFPM generator, a control strategy is designed based on Mixed Integer Nonlinear Programming (MINLP) to incorporate both pitch angle and the number of active stator modules as control input signals. These control signals are used in order to maximize system efficiency and regulate output voltage in different wind speeds and electrical loads. Simulation results for a typical generator shows the effectiveness of the proposed method in speed control of the generator.

Multiway data analysis approach toward understanding of photoluminescence and energy transfer in carbon nanodots.

In this study, dilution analysis and anion exchange chromatography (AEC) were employed to provide insights into the photoluminescence (PL) of carbon nanodots (CNDs). A stepwise dilution process revealed that some of the fluorophores with higher energy emission were quenched in the high concentration solution and appeared in the dilute solutions. AEC fractionation led to seven sorts of CND fractions with similar surface charges. The fractionation for this CND mixture showed that excitation wavelength dependence was lower for separated CND particles. The wavelength dependence of excitation spectra could be due to energy exchange between particles that was reduced in diluted solutions and separated fractions. Multivariate analysis of AEC's data demonstrated that there were five distinct fluorophores, which formed the total CND emission. It is interesting that none of these fluorophores had a clear contribution to the surface charge of the CND particles. Further characterization through FTIR spectroscopy and 1 H NMR revealed that optical properties of CNDs did not follow the surface functional groups in CNDs. This situation means that the optical behaviour of particles and their fluorophores differed depending on the surface functional groups.

Unveiling Adsorption of Boron Dipyrromethene Conjugated PbS Nanocrystals on Pt Electrode Surface: An Approach Using Electrogenerated Chemiluminescence Spooling Spectra and Multivariate Analysis.

This research focuses on the adsorption and molecular scale communication mechanism of PbS-BDY (BDY, boron dipyrromethene), a nanohybrid system of nanocrystal (NC) and a π-conjugated molecule, investigated through the electrogenerated chemiluminescence (ECL) spooling spectra and multivariate analysis. The results show that the charge transmitted from the excited state of BDY+ to the surface states of PbS NCs leads to emission quenching of BDY and emission enhancement of PbS NCs at 986 nm. Also, the essence tendency of unpassivated sulfur atoms on (100) facets of the PbS NCs acts as a force for adsorption of PbS NCs on the surface of Pt electrode. This phenomenon was proved by conjugation of BDY as an ECL active compound to the PbS NCs and multivariate analysis of augmented data at different scan rates. The obtained results from multivariate analysis reveal that adsorption of PbS-BDY and charge transfer from BDY to surface states of PbS NCs are independent of the scan rate.

Knowledge and Practice of Junior and Senior High School Students Regarding Violent Behaviors in Isfahan Province.

BACKGROUND: Considering the importance of anger, aggression, violence and other misbehaviours in schoolchildren education, the present study was conducted to evaluate the knowledge and practice of students in Isfahan province regarding violence, in order to figure out the required interventions for violence-reduction. METHODS: In a survey during 2008-2009, 5500 junior and senior high school students of Isfahan province were assessed in a multistage sampling process to determine their level of knowledge about various types of violent behaviors, causes of violence, its consequences, and preventive behaviors. Validity and reliability of the data collection tool (questionnaire) were assessed. RESULTS: The study revealed that the mean scores of violent behaviors knowledge, knowledge of violent behavior outcomes, and knowledge of violence preventive behaviors, were 6.6 ± 2.1, 5.5 ± 1.9, and 4.7 ± 1.3, respectively. Sources of violent behaviors in 92% of urban students and 89% of rural students were personal reasons and family behaviors, and 85% of urban and 88% of rural students considered mass media and computer games blameworthy, and the differences were statistically significant in all cases (P < 0.0001). In terms of practice, overall, 69.7% of girls and 84.2% of boys had violent behaviors. Physical and verbal violence were 31.3% and 40.7%in girls, and 66% and 52.8% in boys, respectively (intersexes P values were P < 0.001 and P = 0.7 respectively, and intra-sex P value was P < 0.0001). CONCLUSIONS: Results showed that girls and city dwellers were more aware of recognizing violent behaviors, outcomes, and causes, compared with boys and villagers, and in terms of general practice, violence was observed among boys more than girls. Further complementary studies in this area seem required.

Body Mass Index, Weight-for-age, and Stature-for-age Indices in Iranian School Children in Relation to Weight and Growth Disorders: A Population-based Survey.

BACKGROUND: Present study aimed to evaluate the prevalence of grades of nutritional status comprising underweight, normal weight, overweight, and obesity as well as other measurable anthropometric indicators of body mass index (BMI) in regard to gender, educational level, and living area among students settled in Isfahan province. METHODS: This cross-sectional study was conducted on a sample of 4700 individuals (2349 females and 2351 males) being from 9 to 15 years old, while they were students of either primary school or junior high school. Random cluster method was applied in both urban (84%) and rural (16%) areas of Isfahan province. BMI values were measured and then categorized using reference growth charts from the Centers for Disease Control and Prevention (CDC 2000). Weight-for-age and stature-for-age indices were assessed as well in accordance with CDC growth charts. RESULTS: The overall prevalence of underweight, overweight, and obesity was 13.9, 10.4, and 5.7%, respectively. Boys and students of urban areas showed a higher tendency of obesity and overweight in comparison with girls and rural students respectively. Furthermore, rural students had poorer status in both weight-for-age and stature-for-age indices. In addition, educational level was the only statistically efficacious factor. CONCLUSIONS: This study and previous ones demonstrated that children and adolescents' nutritional status, which strongly affect general health status of individuals, should receive more exquisite attention.

Improved resolution three-dimensional integral imaging using optimized irregular lens-array structure.

A rigorous approach is proposed to improve the resolution of integral imaging (InI) by finding the appropriate form of irregularity in the arrangement of the InI lenslets. The improvement of the resolution is achieved through redistribution of the sampling points in a uniform manner. The optimization process for finding the optimum pattern of the lens-array irregularity is carried out by minimizing a cost function, whose mathematical closed-form expression is provided. The minimization of the proposed cost function ensures the uniform distribution of sampling points and thus improves the resolution within the desired depth of field (DOF) and field of view (FOV). A set of standard resolution charts is used to demonstrate the improvement of the quality of the three-dimensional (3D) images obtained by using the optimized irregular lens array. It is shown that the overall level of the lateral and depth resolutions is improved at the same time.

Three-dimensional resolvability in an integral imaging system.

The concept of three-dimensional (3D) resolvability of an integral imaging system is thoroughly investigated in this research. The general concept of 3D resolution fails to describe the 3D discrimination completely. Then the concepts of the depth-resolution plane and lateral-resolution plane are introduced to show the difference between the conventional 3D spatial resolution and the newly introduced 3D resolvability. Therefore, the different properties of these planes for differentiating lateral spatial variations and axial variations are analyzed in this paper. The theoretical statements are demonstrated experimentally.

Optimization of the lens-array structure for performance improvement of integral imaging.

The seemingly inherent deficiencies of integral imaging systems-in particular, the depth of field limitation-are, in this Letter, partly resolved by using an irregular lens array, where each lens is either rotated or displaced from its original position in the conventional flat lens array. It is shown that having an array of lenses in the integral imaging system has some sort of redundancy that could be exploited to improve the quality of the image formation. The needed rotation or displacement of constituent lenses in the array is found by using a meticulous optimization algorithm, which tries to evenly distribute the optical rays emanating from each of the lenses to form the final image.

Signal-to-noise-ratio limit to the depth-of-field extension for imaging systems with an arbitrary pupil function.

We discuss the limit of the depth-of-field (DOF) extension for an imaging system using aspheric surfaces. In particular we consider an imaging system with an arbitrary pupil function and present the rigorous tradeoff between the DOF of the system and the spectral signal-to-noise ratio (SNR) over an extended DOF, to our knowledge for the first time. In doing so we use the relation between the conservation of ambiguity and modulation-transfer function (MTF) on one hand and the relation between the spectral SNR and MTF on the other. Using this, we rigorously derive the expression for an upper bound for the minimum spectral SNR, i.e., the limit of spectral SNR improvement. This leads to the introduction of our spectral SNR conservation principle. We also draw the relation between our result and the conservation of brightness theorem and establish that our result is the spectral version of the brightness conservation theorem.

Analytical optimal solution of the extension of the depth of field using cubic-phase wavefront coding. Part I. Reduced-complexity approximate representation of the modulation transfer function.

In this paper we derive an approximate analytical representation for the modulation transfer function (MTF) of an imaging system possessing a defocused cubic-phase pupil function. This expression is based on an approximation using the Arctan function and significantly reduces the computational time required to calculate the resulting MTF. We derive rigorous bounds on the minimum and average accuracy of our approximation. Using this approximate representation of the MTF, the analytical solution of the problem of calculating the extension of the depth of field for a circular aperture with a cubic phase mask becomes possible. We also comment on how one can modify our method to construct a lower-bound or an upper-bound approximate analytical expression for the MTF.

Analytical optical solution of the extension of the depth of field using cubic-phase wavefront coding. Part II. Design and optimization of the cubic phase.

In this paper we use our derived approximate representation of the modulation transfer function to analytically solve the problem of the extension of the depth of field for two cases of interest: uniform quality imaging and task-based imaging. We derive the optimal result for each case as a function of the problem specifications. We also compare the two different imaging cases and discuss the advantages of using our optimization approach for each case. We also show how the analytical solutions given in this paper can be used as a convenient design tool as opposed to previous lengthy numerical optimizations.

Extension of depth of field using amplitude and phase modulation of the pupil function.

We analyze the extension of depth of field using both amplitude and phase modulation of the pupil function. In particular, we discuss the advantages and disadvantages of each approach and establish the range of applicability of each method based on the range of spatial frequencies of interest in the imaging system. To the best of our knowledge, this is the first such report on the range of applicability of amplitude and phase modulation to extend the depth of field.

Reduced-complexity representation of the coherent point-spread function in the presence of aberrations and arbitrarily large defocus.

We introduce a method to analyze the diffraction integral for evaluating the point-spread function. Our method is based on the use of higher-order Airy functions along with Zernike and Taylor expansions. Our approach is applicable when we are considering a finite, arbitrary number of aberrations and arbitrarily large defocus simultaneously. We present an upper bound for the complexity and the convergence rate of this method. We also compare the cost and accuracy of this method with those of traditional ones and show the efficiency of our method through these comparisons. In particular, we rigorously show that this method is constructed in a way that the complexity of the analysis (i.e., the number of terms needed for expressing the light disturbance) does not increase as either defocus or resolution of interest increases. This has applications in several fields such as biological microscopy, lithography, and multidomain optimization in optical systems.