Nanorod

Mechanical alloying has been widely utilized to break down the clustered CNTs for incorporation in the metal matrix composites. However, the breakage of CNTs during the ball milling process degrades their effectiveness. Due to the challenges in collecting the CNTs for measurement, quantitative study of CNT breakage has been difficult. In this study, the CNTs with Al6061 powder were mechanically alloyed with high energy milling equipment. The CNTs from the surface of mechanically alloyed particles were collected and measured. Due to the difficulty in obtaining the CNTs embedded inside the particles, a mathematical model has been developed to predict the overall CNT length distribution in the composite. Significant CNT breakage occurred during the initial phase of the mechanical alloying due to the crushing of the clusters. The model predicted that no further change occurred in the overall CNT length during time greater than 1 h of mechanical alloying because most of the CNTs had already become embedded within the particles and were thus protected from further milling media impacts. A faster dispersion of CNTs and lower particle fracturing rate may help preserve the original CNTs.

Cesium doped zirconium vanadate ZrV2O7 with different Cs dopant content (Cs/Zr varied
from 0 to 0.5 in weight ratio) were fabricated by hydrothermal technique at 120
C for
60 min. The synthesized materials are thermally treated using microwave technique. The
structural and morphological properties of the synthesized materials and thermally
treated samples were investigated using XRD and SEM respectively. It was evident that all
synthesized specimens have cubic phase structural without any extra phase but after heat
treatment Orthorhombic phase appear with doped samples. However, the morphological
structure of the doped synthesized materials has transferred from nanoparticles into rods
aspect with heat treatment for the different dopant ratio. Moreover, the electrical properties
of both the synthesized and thermally treated materials are studied by AC impedance
measurements. The results indicated that the ionic conductivity of Cs-doped ZrV2O7
materials decreased by increasing the dopant ratio while that thermally treated samples
the ionic conductivity increase by increasing the dopant ratio. Finally, the concentration of
cesium dopants is found to play crucial role in tuning the morphology and electrical
properties of nanostructures.

Heterogeneous photocatalysis is a promising technology especially for environmental remediation. Despite more than a decade of worldwide research in developing photocatalytic efficiency improving techniques, many questions regarding the large scale application of photocatalytic reactors still remain unanswered. Recently, improving the photocatalytic efficiency has gained scientific attention because it might lead to more economical and robust photocatalytic operation for environmental remediation. In this review, fundamental and comprehensive assessments of the photocatalytic concepts and their applications for environmental remediation are reviewed. The existing challenges and strategies to improve the photocatalytic efficiency are discussed. Further, recent developments and future research prospects on photocatalytic systems for environmental applications are also addressed.

Available data on the iron-containing nanomaterials are reviewed. Main attention is paid to the following themes: synthetic methods, structures, composition and properties of the nano zerovalent iron (NZVI), and polymorphic forms of iron oxides and FeOOH. Synthetic methods summarized here include a series of physico-chemical methods such as microwave heating, electrodeposition, laser ablation, radiolytical techniques, arc discharge, metal-membrane incorporation, pyrolysis, combustion, reverse micelle and co-deposition routes. We have also included a few ''greener'' methods. Coated, doped, supported with polymers or inert inorganic materials, core-shell nanostructures, in particular those of iron and its oxides with gold, are discussed. Studies of remediation involving iron-containing nanomaterials are discussed and special attention is paid to the processes of remediation of organic contaminants (chlorine-containing pollutants, benzoic and formic acids, dyes) and inorganic cations (Zn(II), Cu(II), Cd(II) and Pb(II)) and anions (nitrates, bromates, arsenates). Water disinfection (against viruses and bacteria), toxicity and risks of iron nanomaterials application are also examined.

Available data on the iron-containing nanomaterials are reviewed. Main attention is paid to the following themes: synthetic methods, structures, composition and properties of the nano zerovalent iron (NZVI), and polymorphic forms of iron oxides and FeOOH. Synthetic methods summarized here include a series of physico-chemical methods such as microwave heating, electrodeposition, laser ablation, radiolytical techniques, arc discharge, metal-membrane incorporation, pyrolysis, combustion, reverse micelle and co-deposition routes. We have also included a few ''greener'' methods. Coated, doped, supported with polymers or inert inorganic materials, core-shell nanostructures, in particular those of iron and its oxides with gold, are discussed. Studies of remediation involving iron-containing nanomaterials are discussed and special attention is paid to the processes of remediation of organic contaminants (chlorine-containing pollutants, benzoic and formic acids, dyes) and inorganic cations (Zn(II), Cu(II), Cd(II) and Pb(II)) and anions (nitrates, bromates, arsenates). Water disinfection (against viruses and bacteria), toxicity and risks of iron nanomaterials application are also examined.

Herein, MoS2-ZnO heterostructure nanorods were hydrothermally synthesized and characterized in detail using several compositional, optical, and morphological techniques. The comprehensive characterizations show that the synthesized MoS2/ZnO heterostructure nanorods were composed of wurtzite hexagonal phase of ZnO and rhombohedral phase of MoS2. The synthesized MoS2/ZnO heterostructure nanorods were used as a potent photocatalyst for the decomposition of methylene blue (MB) dye under natural sunlight. The prepared MoS2/ZnO heterostructure nanorods exhibited ~97% removal of MB in the reaction time of 20 min with the catalyst amount of 0.15 g/L. The kinetic study revealed that the photocatalytic removal of MB was found to be in accordance with pseudo first-order reaction kinetics with an obtained rate constant of 0.16262 min−1. The tremendous photocatalytic performance of MoS2-ZnO heterostructure nanorods could be accredited to an effective charge transportation and inhibition in the r...

Hematite  (a-Fe2O3)  and  Fe2O3–SnO2composite  nanorods  were  synthesized  by  a  facile  low  cost  wet
chemical  method  followed  by  calcination  at  500


C.  The  synthesized  nanomaterials  were  characterized
by  X-ray  diffraction  (XRD),  scanning  electron  microscopy  (SEM),  transmission  electron  microscopy
(TEM),  Fourier  transform  infrared  (FTIR),  and  Raman  spectroscopic  techniques.  XRD  study  showed  the
presence  of  magnetic  g-Fe2O3phase  along  with  SnO2for  Fe2O3–SnO2composite  nanorods,  calcined  at
500


C  temperature.  However,  in  the  absence  of  SnO2formation  of  pure  a-Fe2O3phase  was  observed.
SEM  and  TEM  results  revealed  the  formation  of  uniform  nanorods  with  typical  diameter  100–200  nm.
The  obtained  a-Fe2O3and  Fe2O3–SnO2composite  nanorods  were  used  as  adsorbents  for  removal  of
Congo  red  (CR)  dye  molecules  from  aqueous  solution.  The  adsorption  isotherms  and  kinetics  were
studied.  It  was  observed  that,  Fe2O3–SnO2(Fe:Sn  =  8:2)  composite  nanorod  showed  highest  percentage
adsorption  with  sorption  capacity  of  182  mg/g.

Electrode materials are the most important factors to verify the properties of the electrochemical supercapacitor. In this paper, the storage principles and characteristics of electrode materials, including carbon-based materials, transition metal oxides and conducting polymers for supercapacitors are depicted in detail. Other factors such as electrode separator and electrolyte are brie°y investigated. Recently, several works are conducted on application of multiwalled carbon nanotubes (MWCNTs) and MWCNTs-based electrode materials for supercapacitors. MWCNTs serve in experimental supercapacitor electrode materials result in speci¯c capacitance (SC) value as high as 135 Fg À1 . Addition of pseudocapacitive materials such as transition metal oxides and conducting polymers in the MWCNTs results in electrochemical performance improvement (higher capacitance and conductivity). The nanocomposites of MWCNTs and pseudocapacitive materials are the most promising electrode materials for supercapacitors because of their good electrical conductivity, low cost and high mass density.

Electrode materials are the most important factors to verify the properties of the electrochemical supercapacitor. In this paper, the storage principles and characteristics of electrode materials, including carbon-based materials, transition metal oxides and conducting polymers for supercapacitors are depicted in detail. Other factors such as electrode separator and electrolyte are briefly investigated. Recently, several works are conducted on application of multiwalled carbon nanotubes (MWCNTs) and MWCNTs-based electrode materials for supercapacitors. MWCNTs serve in experimental supercapacitor electrode materials result in specific capacitance (SC) value as high as 135 Fg -1. Addition of pseudocapacitive materials such as transition metal oxides and conducting polymers in the MWCNTs results in electrochemical performance improvement (higher capacitance and conductivity). The nanocomposites of MWCNTs and pseudocapacitive materials are the most promising electrode materials for supercapacitors because of their good electrical conductivity, low cost and high mass density. © 2012 World Scientific Publishing Company.

In this present study, we have synthesized ferrous oxalate nanorods by a modified co-precipitation methods. The obtained nanomaterial (ferrous oxalate nanorod) was calcined at higher temperatures to form both maghemite and hematite nanorods. The morphology, size, crystalline phases, formation and surface area of the nanorods were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscope, ultraviolet-visible diffuse reflectance spectroscope and Brunauer-Emmett-Teller surface area analytical techniques. The results showed that high-yield aligned nanorods with a typical diameter of 100-200 nm and length up to micrometers were formed. The obtained rod-shaped nanomaterials (i.e., ferrous oxalate, maghemite and hematite) were used as adsorbents and were applied to remove Congo red (CR) dye molecules, which was used as a model of organic pollutants in aqueous solution. The adsorption isotherms and kinetics of removal of CR were studied. It was found that the adsorption capacity of maghemite nanorod is highest among the three adsorbents and can be regarded as an effective adsorbent for removal of CR from aqueous solution.

Electrode materials are the most important factors to verify the properties of the electrochemical supercapacitor. In this paper, the storage principles and characteristics of electrode materials, including carbon-based materials, transition metal oxides and conducting polymers for supercapacitors are depicted in detail. Other factors such as electrode separator and electrolyte are brie°y investigated. Recently, several works are conducted on application of multiwalled carbon nanotubes (MWCNTs) and MWCNTs-based electrode materials for supercapacitors. MWCNTs serve in experimental supercapacitor electrode materials result in speci¯c capacitance (SC) value as high as 135 Fg À1 . Addition of pseudocapacitive materials such as transition metal oxides and conducting polymers in the MWCNTs results in electrochemical performance improvement (higher capacitance and conductivity). The nanocomposites of MWCNTs and pseudocapacitive materials are the most promising electrode materials for supercapacitors because of their good electrical conductivity, low cost and high mass density.

Available data on the iron-containing nanomaterials are reviewed. Main attention is paid to the following themes: synthetic methods, structures, composition and properties of the nano zerovalent iron (NZVI), and polymorphic forms of iron oxides and FeOOH. Synthetic methods summarized here include a series of physico-chemical methods such as microwave heating, electrodeposition, laser ablation, radiolytical techniques, arc discharge, metal-membrane incorporation, pyrolysis, combustion, reverse micelle and co-deposition routes. We have also included a few ''greener'' methods. Coated, doped, supported with polymers or inert inorganic materials, core-shell nanostructures, in particular those of iron and its oxides with gold, are discussed. Studies of remediation involving iron-containing nanomaterials are discussed and special attention is paid to the processes of remediation of organic contaminants (chlorine-containing pollutants, benzoic and formic acids, dyes) and inorganic cations (Zn(II), Cu(II), Cd(II) and Pb(II)) and anions (nitrates, bromates, arsenates). Water disinfection (against viruses and bacteria), toxicity and risks of iron nanomaterials application are also examined.

""The main technological difficulties concerning the development of a promising fine grain siliconized graphite are discussed. Comprehensive selection of carbon filler and formation of optimum porous structure for
its infiltration by silicon melt was shown to  enable manufacture of SiC material with excellent characteristics
comparable with materials produced, for example,  by Schunk, Coorstek, Morgan MT."
for more details contact me by the email- [email protected]

We review progress in the development of organic-inorganic hybrid photovoltaic materials consisting of a conjugated polymer as an electron donor and a nanocrystalline metal oxide as the electron acceptor. We distinguish two main approaches: (1) where a rigid porous metal oxide structure is filled with polymer and where metal oxide nanoparticles and polymer are codeposited from solution to form a blend film. In the case of porous structures, performance is limited by the infiltration of polymer into the pores of the metal oxide and control of the nanostructure dimensions. In the case of blends, control of the blend morphology and transport between nanoparticles are limitations. In both cases, further improvements are possible by modifying the metal oxide organic interface to optimise charge transfer, by improving both interand intra-particle transport within the metal oxide phase, for example by the use of single crystalline nanorods, and by optimising the choice of electrode materials. Though unlikely to achieve the highest photocurrents, the polymer-metal oxide composites provide a model system to study the effects of interface properties and film morphology on the performance of bulk heterojunction photovoltaic devices.

Colloidal quantum dot light-emitting devices (QD-LEDs) have generated considerable interest for applications such as thin film displays with improved color saturation and white lighting with a high color rendering index (CRI). We review the key advantages of using quantum dots (QDs) in display and lighting applications, including their color purity, solution processability, and stability. After highlighting the main developments in QD-LED technology in the past 15 years, we describe the three mechanisms for exciting QDs Á optical excitation, Fö rster energy transfer, and direct charge injection Á that have been leveraged to create QD-LEDs. We outline the challenges facing QD-LED development, such as QD charging and QD luminescence quenching in QD thin films. We describe how optical downconversion schemes have enabled researchers to overcome these challenges and develop commercial lighting products that incorporate QDs to achieve desired color temperature and a high CRI while maintaining efficiencies comparable to inorganic white LEDs (65 lumens per Watt). We conclude by discussing some current directions in QD research that focus on achieving higher efficiency and air-stable QD-LEDs using electrical excitation of the luminescent QDs.

b S Supporting Information T echnologies to utilize renewable energy such as solar, wind, geothermal, and biomass sources have attracted great attention recently. The large scale chemical energy stored as the salinity difference between seawater and freshwater is another renewable source which can be harvested. The major components of the global water cycle involve distillation of water from oceans by evaporation, precipitation, and collection of this freshwater in rivers, lakes, and aquifers, with mixing of freshwater and salt water in estuaries. Solar energy drives this cycle, creating a significant salinity difference between seawater and freshwater. The entropic energy created by the difference in water salinities is normally dissipated when river water flows into the sea. This reduction in free energy due to the mixing is estimated at 2.2 kJ of free energy per liter of freshwater.

The research on ZnO has a long history but experiences an extremely vivid revival during the last 10 years. We critically discuss in this didactical review old and new results concentrating on optical properties but presenting shortly also a few aspects of other fields like transport or magnetic properties. We start generally with the properties of bulk samples, proceed then to epitaxial layers and nanorods, which have in many respects properties identical to bulk samples and end in several cases with data on quantum wells or nano crystallites. Since it is a didactical review, we present explicitly misconceptions found frequently in submitted or published papers, with the aim to help young scientists entering this field to improve the quality of their submitted manuscripts. We finish with an appendix on quasi two-and one-dimensional exciton cavity polaritons.

In recent years, much effort have been dedicated to achieve thin, lightweight and even flexible energy-storage devices for wearable electronics. Here we demonstrate a novel kind of ultrathin all-solid-state supercapacitor configuration with an extremely simple process using two slightly separated polyaniline-based electrodes well solidified in the H2SO4-polyvinyl alcohol gel electrolyte. The thickness of the entire device is much comparable to that of a piece of commercial standard A4 print paper. Under its highly flexible (twisting) state, the integrate device shows a high specific capacitance of 350 F/g for the electrode materials, well cycle stability after 1000 cycles and a leakage current of as small as 17.2 μA. Furthermore, due to its polymer-based component structure, it has a specific capacitance of as high as 31.4 F/g for the entire device, which is more than 6 times that of current high-level commercial supercapacitor products. These highly flexible and all-solid-state paperlike polymer supercapacitors may bring new design opportunities of device configuration for energy-storage devices in the future wearable electronic area.

pi-Conjugated molecular materials with fused rings are the focus of considerable interest in the emerging area of organic electronics, since the combination of excellent charge carrier mobility and high stability may lead to their practical applications. This tutorial review discusses the synthesis, properties and applications of pi-conjugated organic semiconducting materials, especially those with fused rings. The achievements to date, the remaining problems and challenges, and the key research that needs to be done in the near future are all discussed.

We assess the influence of the degree of quantum confinement on the carrier recovery times in semiconductor optical amplifiers (SOAs) through an experimental comparative study of three amplifiers, one InAs-InGaAsP-InP quantum dot (0-D), one InAs-InAlGaAs-InP quantum dash (1-D), and one InGaAsP-In-GaAsP-InP quantum well (2-D), all of which operate near 1.55-m wavelengths. The short-lived (around 1 ps) and long-lived (up to 2 ns) amplitude and phase dynamics of the three devices are characterized via heterodyne pump-probe measurements. The quantum-dot device is found to have the shortest long-lived gain recovery ( 80 ps) as well as gain and phase changes indicative of a smaller linewidth enhancement factor, making it the most promising for high-bit-rate applications. The quantum-dot amplifier is also found to have reduced ultrafast transients, due to a lower carrier density in the dots. The quantum-dot gain saturation characteristics and temporal dynamics also provide insight into the nature of the dot energy-level occupancy and the interactions of the dot states with the wetting layer.

Abstract This paper reports the facile synthesis of vanadium phosphate (VPO) by the decomposition of VOHPO4·0.5H2O which was prepared by reduction of dihydrate VOPO4·2H2O with isobutanol. The material was promoted with aluminum by impregnation method. The catalysts were unambiguously characterized by N2 adsorption–desorption, XRD, FT-IR techniques, UV–Vis DRS and the total amount of the acidity of the catalysts was estimated by NH3-TPD. The catalytic activities were checked in the heterogeneous catalytic esterification of acetic acid with 1° alcohol (n-butanol) in a solvent free medium. The optimization of reaction was carried out by varying temperature from 75 to 150 °C, molar ratio (butanol:acetic acid) from 1:1 to 1:4. Under optimum conditions, the catalytic esterification runs revealed a significant effect of the VPO giving 62% conversion with 100% selectivity to butyl acetate. Graphical Abstract Vanadium Phosphate is prepared in aqueous medium by taking vanadium pentoxide, o-phosphoric acid and isobutanol. The catalyst is found to be robust enough to achieve high degree of esterification under solvent free condition.

Gold nanomaterials (Au NMs) have been explored for a wide range of applications in catalysis and medicine. Here we report the shape sensitive toxicity of gold nanoplates (Au nanoplates) in breast cancer cell line, MCF7. Au nanoplates induced a dose-and shape-dependent toxicity to cancer cells. Oxidative stress induced by Au nanoplates is believed to be the trigger for the DNA, which resulted in cell apoptosis. In summary, the results from our study demonstrate that morphology appears to play a significant role in mediating the cellular responses and Au triangles nanoplates showed the highest toxicity to the cells. Such findings may be able to shine more light on the shape-dependent interaction between Au NMs and living organisms.

For ex-situ co-doping methods, sintering at high temperatures enables rapid diffusion of Sn 4+ and Be 2+ dopants into hematite (α–Fe 2 O 3) lattices, without altering the nanorod morphology or damaging their crystallinity. Sn/Be co-doping results in a remarkable enhancement in photocurrent (1.7 mA/cm 2) compared to pristine α–Fe 2 O 3 (0.7 mA/cm 2), and Sn 4+ mono-doped α-Fe 2 O 3 photoanodes (1.0 mA/cm 2). From first-principles calculations, we found that Sn 4+ doping induced a shallow donor level below the conduction band minimum, which does not contribute to increase electrical conductivity and photocurrent because of its localized nature. Additionally, Sn 4+-doping induce local micro-strain and a decreased Fe-O bond ordering. When Be 2+ was co-doped with Sn 4+-doped α–Fe 2 O 3 photoanodes, the conduction band recovered its original state, without localized impurities peaks, also a reduction in micro-strain and increased Fe-O bond ordering is observed. Also the sequence in which the ex-situ co-doping is carried out is very crucial, as Be/Sn co-doping sequence induces many under-coordinated O atoms resulting in a higher micro-strain and lower charge separation efficiency resulting undesired electron recombination. Here, we perform a detailed systematic characterization using XRD, FESEM, XPS and comprehensive electrochemical and photoelectrochemical studies, along with sophisticated synchrotron diffraction studies and extended X-ray absorption fine structure.

We develop an analytical formulation describing propagating flexural waves in periodically simplysupported nanoribbons by means of Eringen's nonlocal elasticity. The nonlocal length scale is identified via atomistic finite element (FE) models of graphene nanoribbons with Floquet's boundary conditions. The analytical model is calibrated through the atomistic finite element approach. This is done by matching the nondimensional frequencies predicted by the analytical nonlocal model and those obtained by the atomistic FE simulations. We show that a nanoribbon with periodically supported boundary conditions does exhibit artificial pass-stop band characteristics. Moreover, the nonlocal elasticity solution proposed in this paper captures the dispersive behaviour of nanoribbons when an increasing number of flexural modes are considered. *

Nanorods of ZnO have been selectively produced in a simple aqueous system prepared by mixing Zn(NO 3 ) 2 and NaOH solutions. Also, semi-spherical ZnO nanoparticles have been obtained by adding KNO 3 and K 2 SO 4 solutions to the Zn(NO 3 ) 2 /NaOH mother solutions at different molar ratios of KNO 3 /Zn(NO 3 ) 2 and K 2 SO 4 /Zn(NO 3 ) 2 , but with using LiNO 3 at different molar ratios, the nano particles shape was different and not semi-spherical. The products have been characterized by X-ray diffraction (XRD) and FT-IR spectroscopy. The XRD patterns of samples were in agreement with that of the typical wurtzite structure ZnO and the sharp diffraction peaks indicated good crystallinity of the ZnO nanoparticles .The morphologies of the particles have been studied with a scanning electron microscope (SEM) and a transition electron microscope (TEM), and their average size has been determined by means of an X-ray line-broadening method using the Scherrer equation. The results showed that the presence of K 2 SO 4 , KNO 3 or LiNO 3 led to the formation of slightly smaller ZnO nanoparticles. Chemical component analysis by energy-dispersive spectroscopy (EDS) showed that the ZnO nanoparticles were free from impurities.

MgO nanorods, hierarchical nanostructures and nanoflakes were synthesized by precipitation, reflux and hydrothermal methods, respectively. The SEM and FESEM images suggested the formation of nanorods with diameter around 400-500 nm, hierarchical nanostructures containing plates with thickness around 100-200 nm and nanoflakes with diameter around 300-500 nm. XRD and FTIR confirmed the formation of single phase MgO with well crystalline nature. The hierarchical MgO nanostructures possessed higher specific surface area (147.5 m 2 /g) than MgO nanorods (48.45 m 2 /g) and nanoflakes (110.9 m 2 /g). The prepared nanomaterials were used as adsorbents to remove organic dyes such as Malachite green and Congo red from aqueous media. The percentage of removal of Malachite green by MgO nanorods, hierarchical nanostructures and nanoflakes are 95.1, 99.98 and 97.42%, respectively, and percentage of removal of Congo red by MgO nanorods, hierarchical nanostructures and nanoflakes are 86.28, 99.94 and 92.68%, respectively. The hierarchical MgO nanostructure exhibited excellent adsorption performance for removal of Malachite green and Congo red with maximum sorption capacities of 1205.23 and 1050.81 mg/g, respectively.

Most of the interesting physics of graphene results from the singular electronic band structure at the so-called Dirac point, where the conduction and valence bands cross in momentum space. Although graphene is very stable thermodynamically, the electronic structure at the Dirac point facilitates basal plane chemistry including pericyclic reactions such as the Diels–Alder reaction.

We have discovered a series of facile Diels–Alder reactions in which graphene can function either as a diene when paired with tetracyanoethylene and maleic anhydride or as a dienophile when paired with 2,3-dimethoxybutadiene and 9-methylanthracene. In this Account, we seek to rationalize these findings using simple arguments based on considerations of orbital symmetry and the frontier molecular orbital theory.

The graphene conduction and valence bands (HOMO and LUMO) cross at the Dirac point, which defines the work function (W = 4.6 eV). Thus, the HOMO and LUMO form a degenerate pair of orbitals at this point in momentum space with the same ionization potential (IP) and electron affinity (EA). Based on the importance of the energies of the HOMO (-IP) and LUMO (-EA) in frontier molecular orbital (FMO) theory, graphene should be a reactive partner in Diels–Alder reactions due to the very high-lying HOMO and low-lying LUMO (energies of −4.6 eV). Inspection of the orbital symmetries of the degenerate pair of half-occupied band orbitals at the Dirac point confirms that with the appropriate orbital occupancies, both diene and dienophile reaction partners should undergo concerted Diels–Alder reactions with graphene that are allowed based on the Woodward–Hoffmann principles of orbital symmetry.

Vertical arrays of ZnO nanowires can decouple light absorption from carrier collection in PbS quantum dot solar cells and increase power conversion efficiencies by 35%. The resulting ordered bulk heterojunction devices achieve short-circuit current densities in excess of 20 mA cm−2 and efficiencies of up to 4.9%.

We develop a versatile master equation approach to describe the nonequilibrium dynamics of a two-level system in contact with a bosonic environment, which allows for the exploration of a wide range of parameter regimes within a single formalism. As an experimentally relevant example, we apply this technique to the study of excitonic Rabi rotations in a driven quantum dot, and compare its predictions to the numerical Feynman integral approach. We find excellent agreement between the two methods across a generally difficult range of parameters. In particular, the variational master equation technique captures effects usually considered to be nonperturbative, such as multiphonon processes and bath-induced driving renormalization, and can give reliable results even in regimes in which previous master equation approaches fail.

ZnO nanorods (NRs) films, nitrogen-doped (ZnO:N), and ZnO doped with nitrogen and decorated with silver nanostructures (ZnO:N-Ag) NRs films were vertically supported on undoped and N doped ZnO seed layers by a wet chemical method. The obtained films were characterized structurally by X-ray diffraction. Morphological and elemental analysis was performed by scanning electron microscopy, including an energy dispersive X-ray spectroscopy facility and their optical properties by Ultraviolet-Visible Spectroscopy. Analysis performed in the NRs films showed that the nitrogen content in the seed layer strongly affected their structure and morphology. The mean diameter of ZnO NRs ranged from 70 to 190 nm. As the nitrogen content in the seed layer increased, the mean diameter of ZnO:N NRs increased from 132 to 250 nm and the diameter dispersion decreased. This diameter increase occurs simultaneously with the incorporation of nitrogen into the ZnO crystal lattice and the increase in the volume ...

Modeling and simulation of TiO 2 nanorod based DSSC are done to explore the effect of nanorod diameter on the short-circuit current density. The results show that the porosity decreases with increasing diameter of nanorod for a fixed value of inter-rod separation. The short-circuit current density can be improved by optimizing the nanorod diameter. From this study it could be observed that the nanorods of diameter from 65 nm to 90 nm with a porosity range from 0.43 to 0.66 would result in better performing DSSC. The peak value of current density of 23.96 mA/cm 2 is obtained for the working electrode with a nanorod diameter of 81 nm of length 12 lm for N719 dye.

Nano-to-submicron sized particles of zinc oxide (ZnO) were synthesized by low temperature hydrolysis method. Organo-ZnO was also synthesized by the aforementioned method in presence of polyethylene glycol (PEG-2000). The synthesized ZnO particles were characterized by infra-red spectroscopy, X-ray diffraction, BET surface area, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). FTIR showed that PEG was present on the ZnO surface. Organo-ZnO exhibited floral-shape morphology consisting of concentric nanorods. The average diameter of the nanorods was $ 250 nm as evident from SEM. TEM showed that the nanorods were made of $ 50 nm sized small particles. UV-absorbance property of ZnO was unaltered even after organic coating.

The ZnS layers morphology, structure, composition, and optical properties were investigated with respect to the precursors (zinc chloride and thiocarbamide, Zn:S) molar ratio in spray solution (1:1, 1:2, and 1:3) and growth temperatures in the range of 400-600 8C. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), UV-VIS, and PL spectroscopy were applied to characterize the ZnS layers. Layers obtained at temperatures up to 450 8C are not well crystallized and contain residues originated from undecomposed precursors. ZnS films become crystalline at T s ¼ 500 8C. Layers grown from 1:1 solution at 550 8C are mixture of ZnS and ZnO phases, whereas at 600 8C layers of ZnO were obtained. Films produced from 1:2 solution at 500-600 8C are of ZnS with a wurtzite structure and E g of 3.66 eV, but contain traces of ZnO phase when grown at 550 or 600 8C. Appearance of ZnO phase in the films grown from 1:1 and 1:2 solutions is explained by the results of the studies on the formation and decomposition of dichlorobis(thiocarbamide) zinc(II) complex as an intermediate compound formed in the solution of zinc chloride and thiocarbamide. Spraying the solutions with Zn:S ¼ 1:3, which contain more thiocarbamide than required for the complex formation, results in singlephase ZnS layers with wurtzite structure at growth temperatures up to 600 8C. Moreover, ZnS layers obtained from 1:3 solution at 550 8C and higher are composed of highly c-axis oriented ZnS nanorod-like crystals with diameter of ca. 80 nm and length of ca. 300 nm.

The water-soluble and biocompatible D-glucuronic acid coated Eu(OH)3 nanorods (average thickness
x average length=90×1183 nm) have been prepared in one-pot synthesis. The D-glucuronic
acid coated Eu(OH)3 nanorods showed a strong fluorescence at ∼600 nm with a narrow emission
band width. A cytotoxicity test by using DU145 cells showed that D-glucuronic acid coated Eu(OH)3
nanorods are not toxic up to 100 M, making them a promising candidate for biomedical applications
such as fluorescent imaging. The minimum Eu concentration needed for a conventional
confocal imaging was estimated to be ∼0.1 mM. Therefore, D-glucuronic acid coated Eu(OH)3
nanorods can be applied to fluorescent imaging. However, a very tiny magnetization of ∼1.2 emu/g
at room temperature and at an applied field of 5 tesla was observed. As a result, very small r1 and
r2 water proton relaxivities were estimated, implying that surface coated Eu(OH)3 nanorods are not
sufficient for MRI contrast agents.

Fully analytic formulas, which do not involve any numerical integration, are derived for the discretized influence functionals of a very extensive assortment of spectral distributions. For Feynman integrals derived using the Trotter splitting and Strang splitting, we present general formulas for the discretized influence functionals in terms of proper integrals of the bath response function. When an analytic expression exists for the bath response function, these integrals can almost always be evaluated analytically. In cases where these proper integrals cannot be integrated analytically, numerically computing them is much faster and less error-prone than calculating the discretized influence functionals in the traditional way, which involves numerically calculating integrals whose bounds are both infinite. As an example, we present the analytic discretized influence functional for a bath response function of the form α(t) = K j pje Ω j t , which is a natural form for many spectral distribution functions (including the very popular Lorentz-Drude/Debye function), and for other spectral distribution functions it is a form that is easily obtainable by a least-squares fit. Evaluating our analytic formulas for this example case is much faster and more rigorous than numerically calculating the discretized influence functional in the traditional way. In the appendix we provide analytic expressions for pj and Ωj for a variety of spectral distribution forms, and as a second example we provide the analytic bath response function and analytic influence functionals for spectral distributions of the form J(ω) ∝ ω s e −(ω/ωc) q . The value of the analytic expression for this bath response function extends beyond its use for calculating Feynman integrals. We also provide open source MATLAB and Mathematica programs to make the results of this paper very easy to implement.

Styrene-Butadiene-Rubber (SBR) is a synthetic rubber copolymer used to fabricate several products. This study aims to demonstrate the use of SBR as feedstock for carbon nanomaterials (nanofibers and nanotubes) growth, and therefore to establish a novel process for destination of waste products containing SBR. A three stage electrically heated flow reactor was used. Small pellets of rubber were pyrolyzed at a temperature of 1000 ºC. The pyrolyzates were mixed with oxygen-containing gases and were burned. The products of combustion were used to synthesize the carbon nanomaterials (CNMs) at the presence of a catalyst. CNMs have a wide range of potential applications due to their extraordinary mechanical, thermal and electrical properties. Produced materials were characterized by SEM and TEM, whereas combustion products were assessed using GC. Results showed that CNMs with outer diameters of 30-100 nm and lengths of about 30 µm were formed. Therefore, it was demonstrated that waste products containing SBR can be used to generate CNMs which are value-added products of intense technological interest.

Manganese dioxide nanorods were synthesized using novel solution route. The phase and microstructure of synthesized materials were identified using X ray diffraction, scanning electron and transmission electron microscopic measurements. The material crystallizes into beta crystallographic phase and consists of nanorods of diameter in the range of about 10-14 nm and length about 50 nm. The Fourier Transform Infrared (FTIR) spectroscopic and thermogravimetric analysis (TGA) measurements were carried out to understand the materials microscopic and thermal properties. The material exhibits characteristic Mn O vibrational frequencies, confirming the phase purity of material. The electrochemical performance of beta MnO2 nanorods was evaluated using cyclic voltammetry and galvanostatic charge and discharge measurements using inhouse developed supercapacitor device assembly. We observed about 125 F per g specific capacitance for beta MnO2 nanorods electrode materials.

We assess the influence of the degree of quantum confinement on the carrier recovery times in semiconductor optical amplifiers (SOAs) through an experimental comparative study of three amplifiers, one InAs-InGaAsP-InP quantum dot (0-D), one InAs-InAlGaAs-InP quantum dash (1-D), and one InGaAsP-In-GaAsP-InP quantum well (2-D), all of which operate near 1.55-m wavelengths. The short-lived (around 1 ps) and long-lived (up to 2 ns) amplitude and phase dynamics of the three devices are characterized via heterodyne pump-probe measurements. The quantum-dot device is found to have the shortest long-lived gain recovery ( 80 ps) as well as gain and phase changes indicative of a smaller linewidth enhancement factor, making it the most promising for high-bit-rate applications. The quantum-dot amplifier is also found to have reduced ultrafast transients, due to a lower carrier density in the dots. The quantum-dot gain saturation characteristics and temporal dynamics also provide insight into the nature of the dot energy-level occupancy and the interactions of the dot states with the wetting layer.