scholarly journals Study of the Optical Properties of Functionalized Gold Nanoparticles in Different Tissues and Their Correlation with the Temperature Increase

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
A. Carrillo-Cazares ◽  
N. P. Jiménez-Mancilla ◽  
M. A. Luna-Gutiérrez ◽  
K. Isaac-Olivé ◽  
M. A. Camacho-López
Keyword(s):  
Cross Sections ◽  
Temperature Increase ◽  
Mie Theory ◽  
Average Temperature ◽  
Theoretical Maximum ◽  
Maximum Value ◽  
Homogeneous Media ◽  
532 Nm ◽  
Different Tissues ◽  
Functionalized Aunps

Mie theory explains the interaction of light with a gold nanoparticle (AuNP) through the absorption (Cabs), scattering (Csca), and extinction (Cext) cross sections. These parameters have been calculated in the case of AuNPs dispersed in homogeneous media, but not for specific tissues. The aim of this research was to theoretically obtain the optical cross sections (Cabs, Csca, and Cext) of functionalized AuNPs in liver and colon tissues through Mie theory and correlate them with the temperature increase observed experimentally in tissues containing AuNPs under plasmonic photothermal irradiation using a Nd-YAG laser (λ = 532 nm). Calculations showed that Cabs represents 98.96±0.03% of Cext at 532 nm. The Cext value for a functionalized AuNP in water was 365.66 nm2 (94% of the theoretical maximum value at 522.5 nm), 404.24 nm2 in colon (98% of the theoretical maximum value at 525 nm), and 442.39 nm2 in liver (96% of the theoretical maximum value at 525 nm). Therefore, nanoparticles irradiated at 532 nm are very close to their resonance value. These results correlated with the experimental irradiation of functionalized AuNPs in different tissues, where the average temperature increase showed the pattern liver > colon > water. The temperature increase observed (ΔT up to 13°C) is sufficient to produce cellular death.

Evaporation and Viscous Flow in Triangular Grooves in Micro Heat Pipes

2005 ◽  
Author(s):  
Mulugeta Markos ◽  
Vladimir S. Ajaev ◽  
G. M. Homsy
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Cross Sections ◽  
Wedge Angle ◽  
Heat Pipes ◽  
Type Model ◽  
Pressure Gradients ◽  
Maximum Value ◽  
Dry Out ◽  
Micro Heat Pipes

We develop a lubrication type model of a liquid flow in a wedge in the limit of small capillary numbers and negligible gravity. The model incorporates the effects of capillary pressure gradients and evaporation. Steady vapor-liquid interface shapes are found for a range of parameters. In the limit of weak evaporation the flow is the same in all cross-sections and can be controlled by changing the wedge angle. We find the wedge angle that results in the maximum value of the flow rate for a given contact angle. For high evaporation rates, both the flow rate and the amount of liquid in each cross-section along the wedge decrease until the point of dry-out is reached. The location of the dry-out point is studied as a function of evaporation. Practical suggestions about optimization of micro heat pipes are given.

Variations of Temperature in Hefei City in Recent 50 Years

2012 ◽  
Vol 616-618 ◽  
pp. 1496-1499
Author(s):  
Guo Wei Xu ◽  
Xin Tian Yuan ◽  
Shu Ling Huang ◽  
Yang Gao
Keyword(s):  
Statistical Analysis ◽  
Temperature Increase ◽  
Summer Temperature ◽  
Observation Data ◽  
Annual Average ◽  
Average Temperature ◽  
Four Seasons ◽  
Temperature Observation ◽  
Significant Temperature ◽  
Annual Average Temperature

Selecting 50 years temperature observation data from1959 to 2008 and using statistical analysis, this paper revealed the characteristics of temperature variation in Hefei city. The results show that in past 50 years, the annual average temperature in Hefei city greatly increased, tendency rate of temperature change was 0.246°C/10 a, especially after 1993, the temperature increased significantly; the temperature in four seasons all increased somewhat, warming was most prominent in spring. The most significant temperature increase was in spring, winter following behind, temperature increase in autumn was not obvious, and the average summer temperature increased the most unobvious.

scholarly journals Measurement and modeling of the multiwavelength optical properties of uncoated flame-generated soot

2018 ◽  
Vol 18 (16) ◽  
pp. 12141-12159 ◽  
Author(s):  
Sara D. Forestieri ◽  
Taylor M. Helgestad ◽  
Andrew T. Lambe ◽  
Lindsay Renbaum-Wolff ◽  
Daniel A. Lack ◽  
...  
Keyword(s):  
Optical Properties ◽  
Cross Sections ◽  
Climate Models ◽  
Complex Refractive Index ◽  
Mie Theory ◽  
Particle Diameter ◽  
Effective Theory ◽  
Soot Particles ◽  
Multiple Wavelengths ◽  
Specific Complex

Abstract. Optical properties of flame-generated black carbon (BC) containing soot particles were quantified at multiple wavelengths for particles produced using two different flames: a methane diffusion flame and an ethylene premixed flame. Measurements were made for (i) nascent soot particles, (ii) thermally denuded nascent particles, and (iii) particles that were coated and then thermally denuded, leading to the collapse of the initially lacy, fractal-like morphology. The measured mass absorption coefficients (MACs) depended on soot maturity and generation but were similar between flames for similar conditions. For mature soot, here corresponding to particles with volume-equivalent diameters >∼160 nm, the MAC and absorption Ångström exponent (AAE) values were independent of particle collapse while the single-scatter albedo increased. The MAC values for these larger particles were also size-independent. The mean MAC value at 532 nm for larger particles was 9.1±1.1 m2 g−1, about 17 % higher than that recommended by Bond and Bergstrom (2006), and the AAE was close to unity. Effective, theory-specific complex refractive index (RI) values are derived from the observations with two widely used methods: Lorenz–Mie theory and the Rayleigh–Debye–Gans (RDG) approximation. Mie theory systematically underpredicts the observed absorption cross sections at all wavelengths for larger particles (with x>0.9) independent of the complex RI used, while RDG provides good agreement. (The dimensionless size parameter x=πdp/λ, where dp is particle diameter and λ is wavelength.) Importantly, this implies that the use of Mie theory within air quality and climate models, as is common, likely leads to underpredictions in the absorption by BC, with the extent of underprediction depending on the assumed BC size distribution and complex RI used. We suggest that it is more appropriate to assume a constant, size-independent (but wavelength-specific) MAC to represent absorption by uncoated BC particles within models.

An eu Law Perspective on the Paris Agreement: Will the eu Consider Strengthening its Mitigation Effort?

Climate Law ◽  
2016 ◽  
Vol 6 (1-2) ◽  
pp. 182-195 ◽  
Author(s):  
Marjan Peeters
Keyword(s):  
European Union ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Temperature Increase ◽  
Paris Agreement ◽  
Eu Law ◽  
The European Union ◽  
Average Temperature ◽  
Mitigation Effort ◽  
The Eu

The European Union is the only party to the unfccc that is a regional organization. The European Union’s Intended Nationally Determined Contribution, submitted on behalf of itself and its member states, contains a pledge to reduce domestic greenhouse gas emissions by at least 40 per cent by 2030 compared with 1990 levels, in pursuit of the general objective to keep the global average temperature increase below 2°C. Given, however, that the Paris Agreement aims not only to hold the increase ‘well below’ 2°C, but also to ‘pursue efforts’ to limit the increase to 1.5°C, one wonders whether the outcome of cop 21 may lead the European Union to a reconsideration—with possibly a strengthening—of the mitigation effort proposed in its indc.

Influence of energy losses on charge distribution of fast ions passing through solid matter

2020 ◽  
Vol 34 (14) ◽  
pp. 2050150
Author(s):  
Yu. A. Belkova ◽  
N. V. Novikov ◽  
Ya. A. Teplova
Keyword(s):  
Charge Distribution ◽  
Cross Sections ◽  
Heavy Ions ◽  
Nuclear Charge ◽  
Target Thickness ◽  
Energy Losses ◽  
Ion Energy ◽  
Fast Ions ◽  
Maximum Value ◽  
Ion Energy Losses

The charge distribution of fast multicharged ions passing through a matter is studied taking ion energy losses into account. Within the framework of the proposed method, we show that the changes in the charge exchange cross-sections, caused by the decreasing of ion energy, affect the process of the formation of the equilibrium ion charge distribution. The target thickness, required for obtaining the equilibrium ion charge distribution, reaches the maximum value for ions without electrons and hydrogen-like ions. The equilibrium target thickness increases with increasing in ion nuclear charge and energy and for fast heavy ions becomes comparable with their range.

Dynamic saturable optical nonlinearities in free base tetrapyridylporphyrin

2003 ◽  
Vol 07 (06) ◽  
pp. 452-456 ◽  
Author(s):  
Newton M. Barbosa Neto ◽  
Leonardo De Boni ◽  
José J. Rodrigues ◽  
Lino Misoguti ◽  
Cléber R. Mendonça ◽  
...  
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Optical Nonlinearities ◽  
Free Base ◽  
Photophysical Parameters ◽  
Crossing Time ◽  
532 Nm

Dynamic optical nonlinearities in free base tetrapyridylporphyrin ( H 2 TPyP ) solutions were investigated at 532 nm with the Z-scan technique. We observed a reverse saturable absorption process that was found to have a fast contribution related to the singlet population and a slow accumulative contribution arising from the triplet population. The optical excitations and subsequent relaxations can be interpreted with a five-energy-level diagram that allows determination of the excited states photophysical parameters such as triplet and singlet absorption cross-sections and the intersystem crossing time.

scholarly journals Determination of the absorption cross sections of higher-order iodine oxides at 355 and 532 nm

2020 ◽  
Vol 20 (18) ◽  
pp. 10865-10887
Author(s):  
Thomas R. Lewis ◽  
Juan Carlos Gómez Martín ◽  
Mark A. Blitz ◽  
Carlos A. Cuevas ◽  
John M. C. Plane ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Atmospheric Chemistry ◽  
Absorption Cross Section ◽  
Particle Formation ◽  
Absorption Cross ◽  
Iodic Acid ◽  
Iodine Oxides ◽  
532 Nm

Abstract. Iodine oxides (IxOy) play an important role in the atmospheric chemistry of iodine. They are initiators of new particle formation events in the coastal and polar boundary layers and act as iodine reservoirs in tropospheric ozone-depleting chemical cycles. Despite the importance of the aforementioned processes, the photochemistry of these molecules has not been studied in detail previously. Here, we report the first determination of the absorption cross sections of IxOy, x=2, 3, 5, y=1–12 at λ=355 nm by combining pulsed laser photolysis of I2∕O3 gas mixtures in air with time-resolved photo-ionization time-of-flight mass spectrometry, using NO2 actinometry for signal calibration. The oxides selected for absorption cross-section determinations are those presenting the strongest signals in the mass spectra, where signals containing four iodine atoms are absent. The method is validated by measuring the absorption cross section of IO at 355 nm, σ355nm,IO= (1.2±0.1) ×10-18 cm2, which is found to be in good agreement with the most recent literature. The results obtained are σ355nm,I2O3<5×10-19 cm2 molec.−1, σ355nm,I2O4= (3.9±1.2)×10-18 cm2 molec.−1, σ355nm,I3O6= (6.1±1.6)×10-18 cm2 molec.−1, σ355nm,I3O7= (5.3±1.4)×10-18 cm2 molec.−1, and σ355nm,I5O12= (9.8±1.0)×10-18 cm2 molec.−1. Photodepletion at λ=532 nm was only observed for OIO, which enabled determination of upper limits for the absorption cross sections of IxOy at 532 nm using OIO as an actinometer. These measurements are supplemented with ab initio calculations of electronic spectra in order to estimate atmospheric photolysis rates J(IxOy). Our results confirm a high J(IxOy) scenario where IxOy is efficiently removed during daytime, implying enhanced iodine-driven ozone depletion and hindering iodine particle formation. Possible I2O3 and I2O4 photolysis products are discussed, including IO3, which may be a precursor to iodic acid (HIO3) in the presence of HO2.

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