A Photon Force and Flow for Dissipative Structuring: Application to Pigments, Plants and Ecosystems

Through a modern derivation of Planck’s formula for the entropy of an arbitrary beam of photons, we derive a general expression for entropy production due to the irreversible process of the absorption of an arbitrary incident photon spectrum in material and its dissipation into an infrared-shifted grey-body emitted spectrum, with the rest being reflected or transmitted. Employing the framework of Classical Irreversible Thermodynamic theory, we define the generalized thermodynamic flow as the flow of photons from the incident beam into the material and the generalized thermodynamic force is, then, the entropy production divided by the photon flow, which is the entropy production per unit photon at a given wavelength. We compare the entropy production of different inorganic and organic materials (water, desert, leaves and forests) under sunlight and show that organic materials are the greater entropy-producing materials. Intriguingly, plant and phytoplankton pigments (including chlorophyll) reach peak absorption exactly where entropy production through photon dissipation is maximal for our solar spectrum 430<λ<550 nm, while photosynthetic efficiency is maximal between 600 and 700 nm. These results suggest that the evolution of pigments, plants and ecosystems has been towards optimizing entropy production, rather than photosynthesis. We propose using the wavelength dependence of global entropy production as a biosignature for discovering life on planets of other stars.

A Photon Force and Flow for Dissipative Structuring: Application to Pigments, Plants and Ecosystems

Through a modern derivation of Planck's formula for the entropy of an arbitrary beam of photons we derive a general expression for the entropy production due to the irreversible process of the absorption of an arbitrary incident photon spectrum in material and its dissipation into an infrared-shifted grey-body emitted spectrum, the rest being reflected or transmitted. Employing the framework of Classical Irreversible Thermodynamic theory, we define the generalized thermodynamic flow as the flow of photons from the incident beam into the material and the generalized thermodynamic force is then just the entropy production divided by the photon flow which is the entropy production per unit photon at a given wavelength. We compare the entropy production under sunlight of different inorganic and organic materials (water, desert, leaves and forests) and show that organic materials are the greater entropy producing materials. Intriguingly, plant and phytoplankton pigments (including chlorophyll) have peak absorption exactly where entropy production through photon dissipation is maximal for our solar spectrum $430&lt;\lambda&lt;550$ nm, while photosynthetic efficiency is maximal between 600 and 700 nm. These results suggest that the evolution of pigments, plants and ecosystems has been towards optimizing entropy production rather than photosynthesis. We propose using the wavelength dependence of global entropy production as a biosignature for discovering life on planets of other stars.

Refractive Index-Based Terahertz Sensor Using Graphene for Material Characterization

In this paper, a graphene-based THz metamaterial has been designed and characterized for use in sensing various refractive index profiles. The proposed single-band THz sensor was constructed using a graphene-metal hybridized periodic metamaterial wherein the unit cell had a footprint of 1.395λeff × 1.395λeff and resonated at 4.4754 THz. The realized peak absorption was 98.88% at 4.4754 THz. The sensitivity of the proposed metamaterial sensor was estimated using the absorption characteristics of the unit cell. The performance of the sensor was analyzed under two different categories, viz. the random dielectric loading and chemical analytes, based on the refractive index. The proposed THz sensor offered a peak sensitivity of 22.75 GHz/Refractive Index Unit (RIU) for the various sample loadings. In addition, the effect of the sample thickness on the sensor performance was analyzed and the results were presented. From the results, it can be inferred that the proposed metamaterial THz sensor that was based on a refractive index is suitable for THz sensing applications.

Photodetector based on Rutile and Anatase TiO2 nanostructures/n-Si Heterojunction

Rutile and anatase titanium dioxide TiO2 nanostructures has been prepared successfully by hydrothermal technique. Also Rutile and anatase TiO2/n-Si heterojunction detector (HJ) has been fabricated. Hall Effect measurements confirmed that prepared films are n-type. The optical absorption spectra showed the prepared films have peak absorption in UV region. TiO2/n-Si heterojunction had exhibited diode-like rectifying I-V behaviour in the dark as well as under the illumination. Ideality factor greater than 2 and rectification factor for Rutile TiO2/n-Si HJ is equal 32.0961 higher than anatase TiO2/n-Si HJ. Photodetetor based on rutile TiO2/n-Si HJ showed higher responsivity and incident photon-to-current efficiency (IPCE) than photodetector based on anatase TiO2/n-Si HJ. Photodetetor based on rutile TiO2/n-Si HJ has responsivity is 69.11Amp/W at 570 nm and IPCE is 21.2%at 370nm and 1.38% at 570nm. For the purpose of investigating the impacts of TiO2 crystal phase upon the performance of the device despite the fact that rutile has a lower band gap compared to anatase, rutile exhibits better photovoltaic activity due to its higher specific surface area.

Functional divergence and spectral tuning of microbial rhodopsins from an ancestral proton pump

For billions of years, life has continuously adapted to dynamic physical conditions near the Earth s surface. Fossils and other preserved biosignatures in the paleontological record are the most direct evidence for reconstructing the broad historical contours of this adaptive interplay. However, biosignatures dating to Earth s earliest history are exceedingly rare. Here, we combine phylogenetic inference of primordial rhodopsin proteins with modeled spectral features of the Precambrian Earth environment to reconstruct the paleobiological history of this essential family of photoactive transmembrane proteins. Our results suggest that ancestral microbial rhodopsins likely acted as light-driven proton pumps, and were spectrally tuned toward the absorption of green light, which would have enabled their hosts to occupy depths in a water column or biofilm where UV wavelengths were attenuated. Subsequent diversification of rhodopsin functions and peak absorption frequencies track the diversification of surface ecological niches induced by the accumulation of atmospheric oxygen. Inferred ancestors retain distinct associations between extant functions and peak absorption frequencies. Our findings suggest that novel information encoded by biomolecules can be used as paleosensors for conditions of ancient, inhabited niches of host organisms not represented elsewhere in the paleontological record. The coupling of functional diversification and spectral tuning of this pervasive protein family underscores the utility of rhodopsins as universal testbeds for inferring remotely detectable biosignatures on inhabited planetary bodies.

Enhanced Refractive Index Sensing Performance Using Hydrothermally Prepared Tricomposite Nanoflower Structure of Ta2O5:Si:Graphite

We describe a tricomposite nanoflower structure based method to measure the trace amount of refractive index in aqueous solutions. It utilizes tantalum (v) oxide, silicon and graphite to fabricate the tricomposite nanostructures. The tricomposite nanoflower structures were prepared using hydrothermal method where the concentration of (x) of Si in Ta2O5 was varied while the concentration of graphite was kept constant. The concentration of Si in Ta2O5 was measured by Maxwell-Garnett model using volume filling factor 'f' (0≤f≤1) of Si in Ta2O5. The fabricated Ta2O5:Si:Graphite tricomposite nanoflower structures were characterized by SEM, XRD, UV-Vis, PL, FTIR characterization techniques. Then aqueous solution of varying refractive indices were prepared in the range 1.33-1.39 in the already prepared tricomposite nanoflower structure solution. The refractive index measurement were probed by measuring absorption spectra corresponding to each tricomposite nanoflower structures. The performance of the sensor was explored in terms of shift in peak absorption spectra, sensitivity and moreover the limit of detection. The sensor shows sensitivity and limit of detection of (156-260) nm/RIU and 5.14x10-3 RIU respectively. A linear declining of sensitivity was observed within the refractive index range. The sensor possesses a distinguished feature of using tricomposite nanoflower structure which is an efficient method for refractive index measurement.

Population Pharmacokinetic Modelling of the Complex Release Kinetics of Octreotide LAR: Defining Sub-Populations by Cluster Analysis

The aim of the study is to develop a population pharmacokinetic (PPK) model, of Octreotide long acting repeatable (LAR) formulation in healthy volunteers, which describes the highly variable, multiple peak absorption pattern of the pharmacokinetics of the drug, in individual and population levels. An empirical absorption model, coupled with a one-compartment distribution model with linear elimination was found to describe the data well. Absorption was modelled as a weighted sum of a first order and three transit compartment absorption processes, with delays and appropriately constrained model parameters. Identifiability analysis verified that all twelve parameters of the structural model are identifiable. A machine learning method, i.e., cluster analysis, was performed as pre-processing of the PK profiles, to define subpopulations, before PPK modelling. It revealed that 13% of the patients deviated considerably from the typical absorption pattern and allowed better characterization of the observed heterogeneity and variability of the study, while the approach may have wider applicability in building PPK models. The final model was evaluated by goodness of fit plots, Visual Predictive Check plots and bootstrap. The present model is the first to describe the multiple-peak absorption pattern observed after octreotide LAR administration and may be useful to provide insights and validate hypotheses regarding release from PLGA-based formulations.

Explaining Colour Change in Pyrope-Spessartine Garnets

A colour-changing garnet exhibits the “alexandrite effect”, whereby its colour changes from green in the presence of daylight to purplish red under incandescent light. This study examines this species of garnets as well as the causes of the colour change by using infrared and ultraviolet visible (UV-Vis) spectroscopy. The infrared spectra show that the colour-changing garnets in this paper belong to the solid solution of pyrope-spessartine type. CIE1931 XYZ colour matching functions are used to calculate the colour parameters influencing garnet colour-changing under different light sources. The UV-Vis spectra show two zones of transmittance, in the red region at 650–700 nm and the blue-green region at 460–510 nm. As they exhibit the same capacity to transmit light, the colour of the gem is determined by the external light source. The absorption bands of Cr3+ and V3+ at 574 nm in the UV-Vis spectra are the main cause of the change in colour. With the increase in the area of peak absorption, the differences in the chroma and colour of the garnet gradually increase in daylight and incandescent light, and it exhibits a more prominent colour-changing effect.

Effects of Accumulated Energy on Nanoparticle Formation in Pulsed-Laser Dewetting of AgCu Thin Films

Ag50Cu50 films were deposited on glass substrates by a sputtering system. Effects of accumulated energy on nanoparticle formation in pulse-laser dewetting of AgCu films were investigated. The results showed that the properties of the dewetted films were found to be dependent on the magnitude of the energy accumulated in the film. For a low energy accumulation, the two distinct nanoparticles had rice-shaped/Ag60Cu40 and hemispherical/Ag80Cu20. Moreover, the absorption spectra contained two peaks at 700 nm and 500 nm, respectively. By contrast, for a high energy accumulation, the nanoparticles had a consistent composition of Ag60Cu40, a mean diameter of 100 nm and a peak absorption wavelength of 550 nm. Overall, the results suggest that a higher Ag content of the induced nanoparticles causes a blue shift of the absorption spectrum, while a smaller particle size induces a red shift.

Pemanfaatan Kacang Hijau Sebagai Sumber Zat Besi Dalam Upaya Pencegahan Anemia Prakonsepsi

High risk groups experience anemia, namely adolescents, especially young women, this is due to the need for iron absorption peaking at the age of 14-15 years while young men, experiencing peak absorption of iron one or two years later. The main risk factors for iron deficiency anemia are low iron intake, poor absorption of iron, and periods of life when the need for iron is high. Food fortification is the most effective way to prevent iron deficiency. One of the foods that can prevent iron is green beans. Consuming 2 cups of green beans every day means consuming 50% of the daily requirement of iron, 18 mg and can increase hemoglobin levels for 2 weeks. The purpose of this PKM is to provide an alternative picture of food in increasing hemoglobin levels in adolescents. The method used in this PKM is screening anemia through examination of hemoglobin and health education in young women in SMK 1 Tegal City. PKM results show that there is an increase in adolescent knowledge about anemia, the number of adolescent girls experiencing anemia is 35% of the total respondents. Iron is the main nutrient that plays an important role in the synthesis of hemoglobin so that the lack of iron intake obtained from food causes hemoglobin levels to decrease.