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Cellulose and lignocellulose have great potential as nanomaterials because they are abundant, renewable, have a nanofibrillar structure, can be made multi¬functional and self-assemble into well-defined architectures. New methods for liberating these materials, including nanodimensional cellulose fibrils, macromolecules and nanominerals will be needed in order to use the techniques developed for other nanomaterials as platforms for creating new wood-based materials and products. Research findings showed promising results in application of nanotechnology at different aspects of papermaking. Electrospinning; chemical treatment followed by mechanical techniques; or mechanical isolation methods were applied by different research groups to prepare cellulose nanofibres.

The introduction of nanoparticles (NPs) and nanostructured materials (NSMs) in papermaking originally emerged from the perspective of improving processing operations and reducing material consumption. However, a very broad range of nanomaterials (NMs) can be incorporated into the paper structure and allows creating paper products with novel properties. This review is of interdisciplinary nature, addressing the emerging area of nanotechnology in papermaking focusing on resources, chemical synthesis and processing, colloidal properties, and deposition methods. An overview of different NMs used in papermaking together with their intrinsic properties and a link to possible applications is presented from a chemical point of view. After a brief introduction on NMs classification and papermaking, their role as additives or pigments in the paper structure is described. The different compositions and morphologies of NMs and NSMs are included, based on wood components, inorganic, organic, carbon-based, and composite NPs. In a first approach, nanopaper substrates are made from fibrillary NPs, including cellulose-based or carbon-based NMs. In a second approach, the NPs can be added to a regular wood pulp as nanofillers or used in coating compositions as nanopigments. The most important processing steps for NMs in papermaking are illustrated including the internal filling of fiber lumen, LbL deposition or fiber wall modification, with important advances in the field on the in situ deposition of NPs on the paper fibers. Usually, the manufacture of products with advanced functionality is associated with complex processes and hazardous materials. A key to success is in understanding how the NMs, cellulose matrix, functional additives, and processes all interact to provide the intended paper functionality while reducing materials waste and keeping the processes simple and energy efficient.

The formation of nanogold and nanosilver composites with cellulose paper fibres and the associated lignin component together with their antimicrobial properties are presented. This follows on from the proprietary technology of Johnston et al. [1] wherein they used nanogold and nanosilver entities in wool fibres to provide novel colourfast colourants in textiles with additional effective antimicrobial and catalytic properties. The nanogold and nanosilver are formed and bound directly onto the unbleached lignin-containing paper fibres without the use of an external linker molecule. For this, the lignin was found to play an essential role and hence the methodology presented is applicable only to cellulose in the form of unbleached kraft fibres and mechanical pulp. The phenol and possibly the aromatic methoxy groups of the lignin are considered to reduce Au3+ to Au0 and Ag+ to Ag0, respectively, and bind the nanogold and nanosilver to the fibre surface. SEM images and UV–Visible spectra confirm the formation of nanogold and nanosilver on the fibre surface. Changes in the IR spectra are consistent with the above role of the phenol and methoxy groups. The resulting nanogold—unbleached kraft fibres are purple and the nanosilver—unbleached kraft fibres are yellow due to the surface plasmon resonance effects of nanogold and nanosilver respectively. The nanogold—unbleached kraft fibres and particularly the nanosilver—unbleached kraft fibres exhibit very effective antimicrobial properties at low levels of gold and at very low levels of silver. In this way we have been able to produce novel nanogold paper and nanosilver paper fibres and products which collectively exhibit the properties of the nanomaterials and the fibre substrates in a synergistic way. This provides the opportunity for developing new functional paper products for antimicrobial packaging, medical dressings, and clothing.

Effective point-of-use devices for providing safe drinking water are urgently needed to reduce the global burden of waterborne disease. Here we show that plant xylem from the sapwood of coniferous trees - a readily available, inexpensive, biodegradable, and disposable material - can remove bacteria from water by simple pressure-driven filtration. Approximately 3 cm3 of sapwood can filter water at the rate of several liters per day, sufficient to meet the clean drinking water needs of one person. The results demonstrate the potential of plant xylem to address the need for pathogen-free drinking water in developing countries and resource-limited settings., Comment: 11 pages, 4 figures

In this paper, we review recent research developments regarding the tribological performances of a series of inorganic nano-additives in lubricating fluids. First, we examine several basic types of inorganic nanomaterials, including metallic nanoparticles, metal oxides, carbon nanomaterials, and “other” nanomaterials. More specifically, the metallic nanoparticles we examine include silver, copper, nickel, molybdenum, and tungsten nanoparticles; the metal oxides include CuO, ZnO, Fe3O4, TiO2, ZrO2, Al2O3, and several double-metal oxides; the carbon nanomaterials include fullerene, carbon quantum dots, carbon nanotubes, graphene, graphene oxides, graphite, and diamond; and the “other” nanomaterials include metal sulfides, rare-earth compounds, layered double hydroxides, clay minerals, hexagonal boron nitride, black phosphorus, and nanocomposites. Second, we summarize the lubrication mechanisms of these nano-additives and identify the factors affecting their tribological performance. Finally, we briefly discuss the challenges faced by inorganic nanoparticles in lubrication applications and discuss future research directions. This review offers new perspectives to improve our understanding of inorganic nano-additives in tribology, as well as several new approaches to expand their practical applications.

Two-dimensional (2D) layered nanomaterials, including layered double hydroxides, graphene, montmorillonite, expandable graphite and molybdenum disulfide, as additives to prepare polymer-based flame retardant nanocomposites, have received much interest in the scientific community in recent years. Based on some unique properties of these layered nanomaterials, as well as different flame-retarding mechanisms, various multifunctional nanocomposites can be designed and fabricated. In this paper, first the flame-retarding mechanisms are discussed. Then, the recent progress in polymer-based flame retardant nanocomposites modified by various 2D layered nanomaterials, including the modification methods, are reviewed. The present status and prospective are also discussed.

In the present work, novel CuS superstructures composed of intersectional CuS nanoplates (CuS i-nanoplates) and snowflake-like CuS nanoplates (CuS s-nanoplates) were successfully synthesized at a low temperature (80 °C) by a simple chemical precipitation method. It has been found that the as-synthesized CuS superstructures were formed by the growth of CuS i-nanoplates along the direction perpendicular to the basal nanoplate with a thickness of 29.64 ± 3.16 nm and CuS s-nanoplates were prepared with the snowflake-like morphology with a thickness of 16.82 ± 3.62 nm. Subsequently, a new transparent heat insulation coating with CuS superstructures composed of CuS i-nanoplates as NIR shielding agent (coded as H–X coating) was prepared by mixing with acrylic-amino-alkyd baking varnish and coating to ordinary glass substrates. Simultaneously, another transparent heat insulation coating with s-nanoplates (coded as S–X coating) was also synthesized. Optical properties of those coatings were studied as a function of the CuS content by using ultraviolet–visible–near-infrared spectrophotometer. And the H–X coatings were shown to have a higher selective shielding ability for solar light than S–X coatings since the shielding ability of S–X coatings in the region of 1180–2500 nm rapidly weakened with increasing wavelength. The comparative study on the properties of nanomaterials with different morphologies in this paper may provide some new guidance for material design to improve its performance. Moreover, the CuS superstructure-based transparent heat insulation coatings with excellent NIR shielding property have a potential application in energy-saving windows for architectures and vehicles.

Multifunctional antireflective (AR) coatings are widely used in fields of optical devices, flat-panel displays, windows and solar cell devices. In this paper, silica (SiO2) and titanium dioxide (TiO2) nanomaterials were used as building blocks to construct multifunctional AR coatings. The surface of the SiO2 coating derived from SiO2 nanoparticles consists of a large number of nanopores, and its refractive index is tuned conveniently from 1.19 to 1.45 by controlled incorporation of TiO2 into these nanopores through a surface sol-gel process. By tuning the coating structure, substrates with double-layer TiO2 SiO2 coatings presented a maxium transmittance of 98.4% and average transmittance as high as 97.7% over the visible and near infrared region. The nanocomposite TiO2 SiO2 coatings demonstrated a good hydrophilicity, favorable robustness and high photocatalytic activity. In addition, the double-layer TiO2 SiO2 coatings had a long-term durability after accelerated-aging test, while the porous SiO2 coatings with a great of open nanopores showed a severe decrease. This double-layer TiO2 SiO2 coatings have the benefit of designing, fabricating, and developing multifunctional AR coatings with broadband transmittance, high photocatalytic activity and high environmental stability, which makes them extremely appealing for applications in lenses, solar photovoltaic cells, etc.. Moreover, this work not only provides an alternative way to tune the refractive indices of AR coatings, but also opens up a new avenue towards broadband AR coatings.

For the most part, the fabrication of nanostructures has been limited to some certain materials. In fact, many researchers view alloys as the last piece of the materials puzzle in the field of nanotechnology. This is the first paper to report on the creation of metallic nanotube arrays (MeNTAs) with highly-ordered periodicity using ferrous (stainless steel) and nonferrous (Cu-, Ni-, Al-, and Ti-based) alloys, as well as elemental metals (Cu, Ag, and Au). The proposed 7 mm × 7 mm MeNTAs were fabricated via sputtering over a contact-hole array template created in photoresist. Extensive analysis revealed many properties typical of nanostructures, including enhanced surface-enhanced Raman scattering (SERS) and high hydrophobicity. The proposed nanotubes can be fabricated over a wide range of heights and diameters (from a few hundred nm to 10 µm) in a variety of shapes, including tall cylinders and dishes. MeNTAs could potentially be used as a platform for the development of nanohybrids in conjunction with nanomaterials such as ZnO nanowires.

Three-dimensional (3D) network structure nanomaterials (NMs) show excellent catalytic performance due to the larger active surface area. A glucose-directed, surfactant-free and one-step direct chemical co-reduction method for synthesis of Pt-Cu alloy nanowires (NWs) under room temperature was demonstrated in present paper. The Pt-Cu NWs were obtained through the co-reduced of CuCl2 and H2PtCl6 by sodium borohydride in the presence of glucose, the glucose in which not only acted as one-dimensional (1D) growth-directing agent, also as the stabilizing agent. The average diameter of NWs was about 3.1 nm and NWs showed typical face-centered-cubic (fcc) alloy crystal structure. The influence of Pt/Cu ions ratios in precursor solution on the bimetallic composition of NWs had been studied, and NWs displayed the feature of composition-tuning. The electro-catalytic activity of Pt-Cu alloy NWs for ethylene glycol oxidation reaction (EGOR) in alkaline medium was strongly related on their compositions. The Pt31Cu69 NWs exhibited about 1.8 times higher than that of commercial Pt/C and higher durability. The enhanced catalytic performance of Pt-Cu alloy NWs was mainly attributed to their unique 3D network structure and the synergetic effects between Pt and Cu.

The paper presents results of optical and surface morphology investigations of semitransparent silver single thin films deposited on glass substrate in relation to their heat radiation treatment. The thickness of 15 nm for the silver thin films was selected using computer designing of optical spectra and the films were deposited using electron beam evaporation process. Optical transmission and reflection were investigated for as deposited samples and after exposition to heat radiation from quartz-halogen lamp. The changes in the optical spectra were observed which suggested degradation of deposited heat mirrors. Structure and surface morphology studies performed using scanning electron microscopy, X-ray photoelectron spectroscopy and atomic force microscopy allowed us to conclude about formation of nanometric silver islands, regularly distributed over the surface of the glass substrate after exposure to heat treatment.

The paper presents the results of an experimental activity aimed at producing and characterizing a nano-encapsulated PEG600 (PCMs) into a silica shell. The nano-encapsulation was meant to be useful to improve the material's suitability to integration in building components. The (300 ± 15) nm nanoparticles that were produced underwent a full characterization of their thermal performances. An enthalpy of fusion as high as 66.24 kJ/kg, in a tight melting temperature range (20–21 °C) was obtained, making the material suitable for thermal energy storage in buildings. In order to demonstrate the benefits of such as this technology on the reduction of heating and cooling demand of buildings, a concentration of 50% in weight of nanoparticles was, then, embedded into a gypsum plasterboard and used for all indoor plastered surfaces of a reference residential buildings. A saving of respectively up to 4.3% and up to 1.1% of heating and cooling energy demand was predicted in comparison to the ones of a building without PCM. Finally, the material underwent a full toxicological characterization exposing human alveolar basal epithelial cells to nanoparticles. The results showed that there were no toxic effects on cell morphology.

In this paper, a mesoporous γ-alumina membrane coated on a macroporous α-alumina support via sol-gel method has been reported. A crack-free γ-alumina membrane was obtained by adding PVA to the alumina solution and optimum parameters of roughness, temperature and porosity were achieved. The support was dip-coated in different solutions using two new different solvents with different particle size distributions. Using these two solvents led to the uniform distribution of pore size in the final membrane. The alumina sols showed particle size distributions in the range of 20 to 55 nm which was measured by a DLS Zeta Sizer. X-ray diffraction technique, atomic force microscopy and scanning electron microscopy were used to characterize the membrane layer. XRD and DTA data for the γ-alumina membrane showed its thermal stability up to around 600 °C. The thickness of the mesoporous γ-alumina membrane was about 4 μm with 16 nm of surface roughness and 5 nm pore size. The resultant crack-free mesoporous membrane shows that the membrane preparation procedure was optimum. In this work, it has been investigated the performance of γ-alumina membranes for single gas permeation and separation of binary gas mixtures.

The preparation process of porous Cu35Ni15Cr alloy was studied in this paper. The effect of ball milling time and sintering temperature on the porosity of Cu35Ni15Cr alloy was identified. It was found that 18 h ball milling and 950 °C sintering are the most promising parameters for the preparation of porous Cu35Ni15Cr alloy. The products have a ~62 % porosity. The alloy consists of an α phase and β phase. The influence of deformation temperature and loading rate on the mechanical properties of Cu35Ni15Cr alloys was investigated. The results show that with decreasing deformation temperature, the yield strength and elastic modulus of the porous alloy increase. With the increase of loading rate, the yield strength of these alloys shows an increasing trend, but the elastic modulus is on a steady level.

The paper presents an investigation on crystalline, elastic and electronic structure in addition to the thermodynamic properties for a CeRu4P12 filled skutterudite device by using the full-potential linear muffin-tin orbital (FP-LMTO) method within the generalized gradient approximations (GGA) in the frame of density functional theory (DFT). For this purpose, the structural properties, such as the equilibrium lattice parameter, bulk modulus and pressure derivatives of the bulk modulus, were computed. By using the total energy variation as a function of strain we have determined the independent elastic constants and their pressure dependence. Additionally, the effect of pressure P and temperature T on the lattice parameters, bulk modulus, thermal expansion coefficient, Debye temperature and the heat capacity for CeRu4P12 compound were investigated taking into consideration the quasi-harmonic Debye model.

The synthesis of trimetallic nanoparticles represents an emerging strategy to maximize catalytic performances in noble metal-based catalysts. However, the controllable synthesis of trimetallic nanomaterials as well as the exact role played by the addition of a third metal in their composition over catalytic performances remains unclear. In this paper, we describe the synthesis of trimetallic nanoshells having AgAuPd, AgAuPt, and AgPdPt compositions by a sequential galvanic replacement reaction approach between Ag nanospheres as sacrificial templates and the corresponding metal precursors, i.e., AuCl4 − (aq), PdCl4 2− (aq), and/or PtCl6 2− (aq). In each of these systems, the composition could be systematically tuned by varying the molar ratios between Ag and each metal precursor. Nanoshells having Ag56Au28Pd16, Ag78Au9Pt13, and Ag71Pd16Pt13 compositions were employed as model systems to investigate the effect of the addition of the third metal in their composition over the catalytic activities toward the 4-nitrophenol reduction. Our data demonstrate a significant enhancement in conversion percentages and thus the catalytic activities relative to the sum of their bimetallic counterparts, and this increase was dependent on the nature of the metals, corresponding to 826, 135, and 56 % for Ag56Au28Pd16, Ag78Au9Pt13, and Ag71Pd16Pt13 nanoshells relative to their bimetallic analogs. The results presented herein demonstrate the strong correlation between catalytic activity and composition in multimetallic nanoshells, and that the incorporation of a third metal may represent a promising approach to boost catalytic activities for a variety of transformations.

This paper reports the successful synthesis of nanostructured forsterite (Mg2SiO4) scaffold with high compressive strength for tissue engineering application. Forsterite slurry was prepared and pre-cut foams were immersed in the slurry for 5 min. The saturated foams were then annealed at various times and temperatures using the two step sintering method. The compressive strength and porosity of the scaffolds were in the range of 0.03–24.16 MPa and 58–88% depends on the heat treatment process, respectively. The 15-60-3 sample consisted of grains in the range of 24–35 nm and micron size pores that could be detected by SEM observation.

Nano has now become a theme in almost all the established discipline. The confluence of innovative methodologies, sophisticated characterisation techniques, and potential technological utility has resulted in intense research activity in the field of polymer nano composites. Polymer composites made out of nano materials display unique properties in terms of improved tensile strength, flexibility, and flexural endurance. The paper discusses the development of polymerclay nano composites, both from the conceptual point of view as well as practical methods for the synthesis of nano composites. These are monomer intercalation, monomer modification, common solvent, and melt-intercalation methods. Various models have been discussed that describe improvements in mechanical and barriers properties due to the incorporation of nano materials. Ongoing R&D work in the two DRDO laboratories on the development of nano composites has been briefly mentioned. The emerging use of polymer-nano composites has also been described.

The evaluation of engineered nanomaterial safety has been hindered by conflicting reports demonstrating differential degrees of toxicity with the same nanoparticles. The unique properties of these materials increase the likelihood that they will interfere with analytical techniques, which may contribute to this phenomenon. We tested the potential for: 1) nanoparticle intrinsic fluorescence/absorbance, 2) interactions between nanoparticles and assay components, and 3) the effects of adding both nanoparticles and analytes to an assay, to interfere with the accurate assessment of toxicity. Silicon, cadmium selenide, titanium dioxide, and helical rosette nanotubes each affected at least one of the six assays tested, resulting in either substantial over- or under-estimations of toxicity. Simulation of realistic assay conditions revealed that interference could not be predicted solely by interactions between nanoparticles and assay components. Moreover, the nature and degree of interference cannot be predicted solely based on our current understanding of nanomaterial behaviour. A literature survey indicated that ca. 95% of papers from 2010 using biochemical techniques to assess nanotoxicity did not account for potential interference of nanoparticles, and this number had not substantially improved in 2012. We provide guidance on avoiding and/or controlling for such interference to improve the accuracy of nanotoxicity assessments.

In this paper, intercalation of nanoclay in the miscible polymer blend of poly(vinylidene fluoride) (PVDF) and acrylic rubber(ACM) was studied. X-ray diffraction was used to investigate the formation of nanoscale polymer blend/clay hybrid. Infrared spectroscopy and X-ray analysis revealed the coexistence of β and γ crystalline forms in PVDF/Clay nanocomposite while α crystalline form was found to be dominant in PVDF/ACM/Clay miscible hybrids. Flory-Huggins interaction parameter (B) was used to further explain the miscibility phenomenon observed. The B parameter was determined by combining the melting point depression and the binary interaction model. The estimated B values for the ternary PVDF/ACM/Clay and PVDF/ACM pairs were all negative, showing both proper intercalation of the polymer melt into the nanoclay galleries and the good miscibility of PVDF and ACM blend. The B value for the PVDF/ACM blend was almost the same as that measured for the PVDF/ACM/Clay hybrid, suggesting that PVDF chains in nanocomposite hybrids interact with ACM chains and that nanoclay in hybrid systems is wrapped by ACM molecules.

In this paper, we describe the effects of the combination of topographical, mechanical, chemical and intracellular electrical stimuli on a co-culture of fibroblasts and skeletal muscle cells. The co-culture was anisotropically grown onto an engineered micro-grooved (10 µm-wide grooves) polyacrylamide substrate, showing a precisely tuned Young's modulus (∼ 14 kPa) and a small thickness (∼ 12 µm). We enhanced the co-culture properties through intracellular stimulation produced by piezoelectric nanostructures (i.e., boron nitride nanotubes) activated by ultrasounds, thus exploiting the ability of boron nitride nanotubes to convert outer mechanical waves (such as ultrasounds) in intracellular electrical stimuli, by exploiting the direct piezoelectric effect. We demonstrated that nanotubes were internalized by muscle cells and localized in both early and late endosomes, while they were not internalized by the underneath fibroblast layer. Muscle cell differentiation benefited from the synergic combination of topographical, mechanical, chemical and nanoparticle-based stimuli, showing good myotube development and alignment towards a preferential direction, as well as high expression of genes encoding key proteins for muscle contraction (i.e., actin and myosin). We also clarified the possible role of fibroblasts in this process, highlighting their response to the above mentioned physical stimuli in terms of gene expression and cytokine production. Finally, calcium imaging-based experiments demonstrated a higher functionality of the stimulated co-cultures.

Carbon nanotubes (CNTs) are often used as conductive fillers in composite materials, but electrical conductivity is limited by the maximum filler concentration that is necessary to maintain composite structures. This paper presents further improvement in electrical conductivity by precipitating gold nanoparticles onto CNTs. In our composites, the concentrations of CNTs and poly (vinyl acetate) were respectively 60 and 10 vol%. Four different gold concentrations, 0, 10, 15, or 20 vol% were used to compare the influence of the gold precipitation on electrical conductivity and thermopower of the composites. The remaining portion was occupied by poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), which de-bundled and stabilized CNTs in water during synthesis processes. The concentrations of gold nanoparticles are below the percolation threshold of similar composites. However, with 15-vol% gold, the electrical conductivity of our composites was as high as ∼6×10(5) S/m, which is at least ∼500% higher than those of similar composites as well as orders of magnitude higher than those of other polymer composites containing CNTs and gold particles. According to our analysis with a variable range hopping model, the high conductivity can be attributed to gold doping on CNT networks. Additionally, the electrical properties of composites made of different types of CNTs were also compared.