These investigations and several others that have beenpublishedwithin recentyears compel us us to hold the view that the ratio of the vital capacity to the body length, trunk length, chest circumference,surfacearea or weight or any combination of thesemeasurements, is too variable to admit of any workable standardor normal value. On the other hand the vital capacity of each individual, after he had becomeaccustomedto the use of the spirometer,will be found to be subjectto but small variations as long as good health is maintained. Thereseems to beevidenceto show that a reductionin the vital capacityis ofen the first sign of a progressivedamageto the respiratorytissue.

The cancer cell

This review critically examines the current state of graphene reinforced metal (GNP-MMC) and ceramic matrix composites (GNP-CMC) The use of graphene as reinforcement for structural materials is motivated by their exceptional mechanical/functional properties and their unique physical/chemical characteristics This review focuses on MMCs and CMCs because of their technological importance for structural applications and the unique challenges associated with developing high-temperature composites with nanoparticle reinforcements The review discusses processing techniques, effects of graphene on the mechanical behaviour of GNP-MMCs and GNP-CMCs, including early studies on the tribological performance of graphene-reinforced composites, where graphene has shown signs of serving as a protective and lubricious phase Additionally, the unique functional properties endowed by graphene to GNP-MMCs and GNP-CMCs, such as enhanced thermal/electrical conductivity, improved oxidation resistance, and excellent bi

Graphene reinforced metal and ceramic matrix composites: a review

Advanced electrocatalysts toward oxygen evolution reaction (OER) at high current density with low overpotential remain a significant challenge for electrochemical water splitting. Herein, NiFe-based catalysts with appropriate electronic conductivity and catalytic activity have been obtained through introduction of oxygen vacancies by a facile and economic NaBH4 reduction approach. The combined density functional theory calculations, physical characterization, and electrochemical studies disclose that the reductive treatment creates a high amount of oxygen vacancies, high active sites, and a low energy barrier for OER. The oxygen vacancy-rich catalyst yields a more than 2-fold increased current density (from 100 to 240 mA cm–2) at a low overpotential of 270 mV, accompanied by good stability under OER conditions. The approach is also broadly applicable for NiFe compounds synthesized via different methods or substrates.

Promoting Oxygen Evolution Reactions through Introduction of Oxygen Vacancies to Benchmark NiFe–OOH Catalysts

This work describes a fast, clean and low-cost approach to synthesize ZnS–PVA nanofluids consisting of ZnS nanoparticles homogeneously distributed in a PVA solution. The ZnS nanoparticles were formed by the electrostatic force between zinc and sulfur ions induced by gamma irradiation at a dose range from 10 to 50 kGy. Several experimental characterizations were conducted to investigate the physical and chemical properties of the samples. Fourier transform infrared spectroscopy (FTIR) was used to determine the chemical structure and bonding conditions of the final products, transmission electron microscopy (TEM) for determining the shape morphology and average particle size, powder X-ray diffraction (XRD) for confirming the formation and crystalline structure of ZnS nanoparticles, UV–visible spectroscopy for measuring the electronic absorption characteristics, transient hot wire (THW) and photoacoustic measurements for measuring the thermal conductivity and thermal effusivity of the samples, from which, for the first time, the values of specific heat and thermal diffusivity of the samples were then calculated.

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Structural, optical, opto-thermal and thermal properties of ZnS-PVA nanofluids synthesized through a radiolytic approach.

Recent years, semiconductor quantum dots (QDs) have attracted tremendous attentions for their unique characteristics for solid-state lighting (SSL) and thin-film display applications. The pure and tunable spectra of QDs make it possible to simultaneously achieve excellent color-rendering properties and high luminous efficiency (LE) when combining colloidal QDs with light-emitting diodes (LEDs). Due to its solution-based synthetic route, QDs are impractical for fabrication of LED. QDs have to be incorporated into polymer matrix, and the mixture is dispensed into the LED mold or placed onto the LED to fabricate the QD–LEDs, which is known as the packaging process. In this process, the compatibility of QDs’ surface ligands with the polymer matrix should be ensured, otherwise the poor compatibility can lead to agglomeration or surface damage of QDs. Besides, combination of QDs–polymer with LED chip is a key step that converts part of blue light into other wavelengths (WLs) of light, so as to generate white light in the end. Since QD-LEDs consist of three or more kinds of QDs, the spectra distribution should be optimized to achieve a high color-rendering ability. This requires both theoretical spectra optimization and experimental validation. In addition, to prolong the reliability and lifetime of QD-LEDs, QDs have to be protected from oxygen and moisture penetration. And the heat generation inside the package should be well controlled because high temperature results in QDs’ thermal quenching, consequently deteriorates QD-LEDs’ performance greatly. Overall, QD-LEDs’ packaging and applications present the abovementioned technical challenges. A profound and comprehensive understanding of these problems enables the advancements of QD-LEDs’ packaging processes and designs. In this review, we summarized the recent progress in the packaging of QD-LEDs. The wide applications of QD-LEDs in lighting and display were overviewed, followed by the challenges and the corresponding progresses for the QD-LEDs’ packaging. This is a domain in which significant progress has been achieved in the last decade, and reporting on these advances will facilitate state-of-the-art QD-LEDs’ packaging and application technologies. [DOI: 10.1115/1.4033143]

Quantum Dots-Converted Light-Emitting Diodes Packaging for Lighting and Display: Status and Perspectives

The present study reports the structural and magnetic characterization of spinel zinc chromite (ZnCr2O4) nanocrystallines synthesized by thermal treatment method. The samples were calcined at different temperatures in the range of 773 to 973K. Polyvinylpyrrolidone was used to control the agglomeration of the nanoparticles. The average particle size of the synthesized nanocrystals was determined by powder X-ray diffraction which shows that the crystallite size increases from 19 nm at 773K to 24 nmat 973 K and the result was in good agreement with the transmission electronmicroscopy images. The elemental composition of the samples was determined by energy dispersed X-ray spectroscopy which confirmed the presence of Zn, Cr, and O in the final products. Fourier transform infrared spectroscopy also confirmed the presence of metal oxide bands for all the samples calcined at different temperature. The band gap energy was calculated from UV-vis reflectance spectra using the Kubelka-Munk function and the band gap energy of the samples was found to decrease from 4.03 eV at 773 K to 3.89 eV at 973 K. The magnetic properties were also demonstrated by electron spin resonance spectroscopy, the presence of unpaired electrons was confirmed, and the resonant magnetic field and the g-factor of the calcined samples were also studied.

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Structural, optical, and magnetic characterization of spinel zinc chromite nanocrystallines synthesised by thermal treatment method

Structural, morphological and optical behaviour of PVP capped binary (ZnO)0.4 (CdO)0.6 nanoparticles synthesised by a facile thermal route

Silver/polyvinyl alcohol (PVA) nanocomposites are prepared via quick precipitation method, using hydrazine as a reducing agent. Preparing of silver/PVA nanocomposites by this method is done for the first time. The samples are characterized by Uv-Visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM). Nonlinear optical properties are carried out by Z-scan technique using a blue CW laser beam operated at wavelength 405 nm. It is shown that the synthesized samples have negative nonlinear refractive index and the magnitude is in the order of 10^-8. The nonlinear refractive index increases as amount of reducing agent increases.

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Synthesis, characterization and nonlinear optical properties of silver/PVA nanocomposites

Monodispersed spherical CdS nanoparticles embedded into polyvinyl alcohol (PVA) films are synthesized by using an in-situ gamma-irradiation-induced method. The formation mechanism of CdS nanoparticles capped by two united cells of PVA is purposed by means of surrounding the CdS nanoparticles with OH bonds of the PVA chain. CdS nanoparticles are found to possess an unusual orthorhombic structure in monoclinic crystalline PVA. The polymer matrix affords protection from agglomeration and controls the particle size. It is found that the distribution of the prepared nanoparticles increases and a narrower size distribution is observed when the gamma radiation is varied from 10 to 50 kGy. While the average size of the nanoparticles is found to be less affected by the variation of the gamma radiation doses. The size range of the synthesized nanoparticles is 14±1 nm. The optical absorption spectra of synthesized CdS nanoparticles in a polymer matrix reveal the blue shift in the band gap energy with respect to CdS bulk materials owing to quantum confinement effect. The photoluminescence study of nanocomposite films shows the green emission arising from the crystalline defects.

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Alireza Kharazmi

Papers

Structural, optical, opto-thermal and thermal properties of ZnS-PVA nanofluids synthesized through a radiolytic approach.

Structural, optical, and magnetic characterization of spinel zinc chromite nanocrystallines synthesised by thermal treatment method

Structural, morphological and optical behaviour of PVP capped binary (ZnO)0.4 (CdO)0.6 nanoparticles synthesised by a facile thermal route

Synthesis, characterization and nonlinear optical properties of silver/PVA nanocomposites

Optical Properties of CdS/PVA Nanocomposite Films Synthesized using the Gamma-Irradiation-Induced Method