Understanding Nanomaterial Biotransformation: An Unmet Challenge to Achieving Predictive Nanotoxicology

More than a decade has passed since the first concepts of predictive nanotoxicology were formulated. During this time, many advancements have been achieved in multiple disciplines, including the success stories of the fiber paradigm and the oxidative stress paradigm. However, important knowledge gaps are slowing down the development of predictive nanotoxicology and require a mutidisciplinary effort to be overcome. Among these gaps, understanding, reproducing, and modeling of nanomaterial biotransformation in biological environments is a central challenge, both in vitro and in silico. This dynamic and complex process is still a challenge for today's bioanalytics. This work explores and discusses selected approaches of the multidisciplinary efforts taken in the last decade and the challenges that remain unmet, in particular concerning nanomaterial biotransformation. It highlights some future advancements that, together, can help to understand such complex processes and accelerate the development of predictive nanotoxicology.     

Porous Silicon Nanoparticle Delivery of Tandem Peptide Anti‐Infectives for the Treatment of Pseudomonas aeruginosa Lung Infections

There is an urgent need for new materials to treat bacterial infections. In order to improve antibacterial delivery, an anti‐infective nanomaterial is developed that utilizes two strategies for localization: i) a biodegradable nanoparticle carrier to localize therapeutics within the tissue, and ii) a novel tandem peptide cargo to localize payload to bacterial membranes. First, a library of antibacterial peptides is screened that combines a membrane‐localizing peptide with a toxic peptide cargo and discovers a tandem peptide that displays synergy between the two domains and is able to kill Pseudomonas aeruginosa at sub‐micromolar concentrations. To apply this material to the lung, the tandem peptide is loaded into porous silicon nanoparticles (pSiNPs). Charged peptide payloads are loaded into the pores of the pSiNP at ≈30% mass loading and ≈90% loading efficiency using phosphonate surface chemistry. When delivered to the lungs of mice, this anti‐infective nanomaterial exhibits improved safety profiles over free peptides. Moreover, treatment of a lung infection of P. aeruginosa results in a large reduction in bacterial numbers and markedly improves survival compared to untreated mice. Collectively, this study presents the selection of a bifunctional peptide‐based anti‐infective agent and its delivery via biodegradable nanoparticles for application to an animal model of lung infection.     

Predicting the Fatigue Life of Different Composite Materials Using Artificial Neural Networks

Artificial Neural Networks (ANN) have been recently used in modeling the mechanical behavior of fiber-reinforced composite materials including fatigue behavior. The use of ANN in predicting fatigue failure in composites would be of great value if one could predict the failure of materials other than those used for training the network. This would allow developers of new materials to estimate in advance the fatigue properties of their material. In this work, experimental fatigue data obtained for certain fiber-reinforced composite materials is used to predict the cyclic behavior of a composite made of a different material. The effect of the neural network architecture and the training function used were also investigated. In general, ANN provided accurate fatigue life prediction for materials not used in training the network when compared to experimentally measured results.     

人工神经网络在材料性能研究中的应用

人工神经网络技术广泛应用于复杂系统的建模中,已成为材料科学研究中常用的建模方法.介绍了BP神经网络及其建模的重要特征,综述了神经网络技术在材料性能预测方面的研究情况.     

Preparation of Nano/Micron Composite Materials by Process Method

This thesis put forward a method that controls the process of synthesizing nanomaterial to realize the composite of nanomaterial and micronmaterial. This thesis realizes the composite of nanomaterial and micronmaterial by adding micronmaterial during production of nanomaterial through sol-gel method, also introduces the technique and experiment's process preparation of nanocomposite material, and successfully prepared nanocomposite materials with nano-PbTiO3 covered on the surface of micron-Ni. According to the sample's SEM-pictures, the core-shell can be observed plate microstructure, and it is uniform, tight, full and good.     

Hybrid Data-Driven and Mechanistic Modeling Approaches for Multiscale Material and Process Design

The world’s increasing population requires the process industry to produce food, fuels, chemicals, and consumer products in a more efficient and sustainable way. Functional process materials lie at the heart of this challenge. Traditionally, new advanced materials are found empirically or through trial-and-error approaches. As theoretical methods and associated tools are being continuously improved and computer power has reached a high level, it is now efficient and popular to use computational methods to guide material selection and design. Due to the strong interaction between material selection and the operation of the process in which the material is used, it is essential to perform material and process design simultaneously. Despite this significant connection, the solution of the integrated material and process design problem is not easy because multiple models at different scales are usually required. Hybrid modeling provides a promising option to tackle such complex design problems. In hybrid modeling, the material properties, which are computationally expensive to obtain, are described by data-driven models, while the well-known process-related principles are represented by mechanistic models. This article highlights the significance of hybrid modeling in multiscale material and process design. The generic design methodology is first introduced. Six important application areas are then selected: four from the chemical engineering field and two from the energy systems engineering domain. For each selected area, state-of-the-art work using hybrid modeling for multiscale material and process design is discussed. Concluding remarks are provided at the end, and current limitations and future opportunities are pointed out.     

Toxicity of Metal Oxide Nanoparticles: Mechanisms,Characterization, and Avoiding Experimental Artefacts

Metal oxide nanomaterials are widely used in practical applications and represent a class of nanomaterials with the highest global annual production. Many of those, such as TiO₂ and ZnO, are generally considered non‐toxic due to the lack of toxicity of the bulk material. However, these materials typically exhibit toxicity to bacteria and fungi, and there have been emerging concerns about their ecotoxicity effects. The understanding of the toxicity mechanisms is incomplete, with different studies often reporting contradictory results. The relationship between the material properties and toxicity appears to be complex and diifficult to understand, which is partly due to incomplete characterization of the nanomaterial, and possibly due to experimental artefacts in the characterization of the nanomaterial and/or its interactions with living organisms. This review discusses the comprehensive characterization of metal oxide nanomaterials and the mechanisms of their toxicity.     

滴加方式对NAC-FAS工艺制备ZnO-TiO_2复合纳米晶的影响

以硫酸氧钛、二水合乙酸锌、氢氧化钠为原料,研究了不同的滴加方式对NAC-FAS工艺制备ZnO-TiO_2复合纳米晶的影响,利用X射线衍射仪(XRD)、透射电子显微镜(TEM)对样品的结构、形貌进行了表征。结果表明:通过NAC-FAS工艺预制TiO_2纳米晶可以制备得到复合ZnO-TiO_2纳米晶,其平均粒径为15nm,复合纳米晶呈球状。通过NAC-FAS工艺直接滴加反应溶液,不能制备得到ZnO-TiO_2,只能制备得到单一晶相或非晶相。     

Implementation of nanotechnology in improving the environmental compliance of construction projects in the United States

Nanotechnology, defined as the science of very small matter called nanomaterial, comprises the study of chemical and physical properties of particles which are structured in sizes ranging from 1 to 100?nm. At this size range, nanomaterial exhibits superior chemical and physical characteristics as compared to those displayed while existing in normal size. To date, multiple nanotechnology research centers within the United States are investigating the potential use of different types of nanoparticles as titanium dioxide (TiO₂) in the construction industry to attain superior characteristics of building materials, improve their rating as environmentally friendly material, and improve the overall LEED rating of construction projects.

The major impediments to the widespread implementation of nanotechnology include high nanomaterial cost, lack of industrial experience, and absence of standard specifications for building materials incorporating nanoparticles. This research article presents a research effort performed to improve the ability of construction material to attain self-cleaning properties through the incorporation of TiO₂ particles in the concrete surface layers. Nanosized TiO₂ particles were able to dissolve induced stains in the presence of sunlight. This chemical reaction, known as photocatalysis, can be successfully used in improving the environmental compliance of construction projects at the US market.     

The radiological properties of a novel lung tissue substitute

Lung phantoms have been manufactured using commercially available, polyurethane foam products. Some of these materials are no longer available; therefore, a new lung tissue substitute was developed. The elemental composition and radiological properties of the new lung tissue substitute are described in this paper. Because the lung tissue substitute will be used to manufacture phantom lungs that will be used to evaluate chest counting systems, it is necessary to know the radiological properties of the material. These properties must be compared with reference materials and materials that have been used for lung phantoms in the past. The radiological properties of interest include the electron density, mean excitation energy, electron stopping power and photon mass attenuation coefficients. In all these properties, the calculated values for the new lung tissue substitute closely matched the calculated values of ICRU Publication 44 lung tissue. Good agreement was also found when the new lung tissue substitute was compared with the Griffith lung tissue substitute described by the ICRU. The new material was determined to be an excellent lung tissue substitute.     

Material Selection for Ceramic Gun Tube Liner

The U.S. Army Research Laboratory is investigating the application of ceramics as bore materials in advanced gun systems. The lower mass and improved high temperature performance of ceramics over traditional gun steels could produce new barrels with improved service life and lower weight while enabling the use of new propellants. Several different ceramics have been researched into which material would best survive the interior ballistic conditions for a variety of different caliber systems. The candidate materials are commercially available monolithic ceramics. Alumina, zirconia, three silicon carbide compositions, two silicon nitride compositions, and a SiAlON material were initially selected. A coupled approach of modeling and experimental verification led to the downselection of the silicon nitride and SiAlON materials as the most capable of surviving the interior ballistic conditions and functioning as a barrel liner. This paper describes the tests, presents the results, and discusses the reasons for these selections.     

Agent-based computational modeling of wounded epithelial cell monolayers

Computational modeling of biological systems, or in silico biology, is an emerging tool for understanding structure and order in biological tissues. Computational models of the behavior of epithelial cells in monolayer cell culture have been developed and used to predict the healing characteristics of scratch wounds made to urothelial cell cultures maintained in low- and physiological [Ca/sup 2+/] environments. Both computational models and in vitro experiments demonstrated that in low exogenous [Ca/sup 2+/], the closure of 500-/spl mu/m scratch wounds was achieved primarily by cell migration into the denuded area. The wound healing rate in low (0.09 mM) [Ca/sup 2+/] was approximately twice as rapid as in physiological (2 mM) [Ca/sup 2+/]. Computational modeling predicted that in cell cultures that are actively proliferating, no increase in the fraction of cells in the S-phase would be expected, and this conclusion was supported experimentally in vitro by bromodeoxyuridine incorporation assay. We have demonstrated that a simple rule-based model of cell behavior, incorporating rules relating to contact inhibition of proliferation and migration, is sufficient to qualitatively predict the calcium-dependent pattern of wound closure observed in vitro. Differences between the in vitro and in silico models suggest a role for wound-induced signaling events in urothelial cell cultures.     

Rising Up: Hierarchical Metal–Organic Frameworks in Experiments and Simulations

Controlled synthesis across several length scales, ranging from discrete molecular building blocks to size‐ and morphology‐controlled nanoparticles to 2D sheets and thin films and finally to 3D architectures, is an advanced and highly active research field within both the metal–organic framework (MOF) domain and the overall material science community. Along with synthetic progress, theoretical simulations of MOF structures and properties have shown tremendous progress in both accuracy and system size. Further advancements in the field of hierarchically structured MOF materials will allow the optimization of their performance; however, this optimization requires a deep understanding of the different synthesis and processing techniques and an enhanced implementation of material modeling. Such modeling approaches will allow us to select and synthesize the highest‐performing structures in a targeted rational manner. Here, recent progress in the synthesis of hierarchically structured MOFs and multiscale modeling and associated simulation techniques is presented, along with a brief overview of the challenges and future perspectives associated with a simulation‐based approach toward the development of advanced hierarchically structured MOF materials.     

Nano/Micro‐Manufacturing of Bioinspired Materials: a Review of Methods to Mimic Natural Structures

Through billions of years of evolution and natural selection, biological systems have developed strategies to achieve advantageous unification between structure and bulk properties. The discovery of these fascinating properties and phenomena has triggered increasing interest in identifying characteristics of biological materials, through modern characterization and modeling techniques. In an effort to produce better engineered materials, scientists and engineers have developed new methods and approaches to construct artificial advanced materials that resemble natural architecture and function. A brief review of typical naturally occurring materials is presented here, with a focus on chemical composition, nano‐structure, and architecture. The critical mechanisms underlying their properties are summarized, with a particular emphasis on the role of material architecture. A review of recent progress on the nano/micro‐manufacturing of bio‐inspired hybrid materials is then presented in detail. In this case, the focus is on nacre and bone‐inspired structural materials, petals and gecko foot‐inspired adhesive films, lotus and mosquito eye inspired superhydrophobic materials, brittlestar and Morpho butterfly‐inspired photonic structured coatings. Finally, some applications, current challenges and future directions with regard to manufacturing bio‐inspired hybrid materials are provided.     

In vivo and in vitro tracking of erosion in biodegradable materials using non-invasive fluorescence imaging

The design of erodible biomaterials relies on the ability to program the in vivo retention time, which necessitates real-time monitoring of erosion. However, in vivo performance cannot always be predicted by traditional determination of in vitro erosion, and standard methods sacrifice samples or animals, preventing sequential measures of the same specimen. We harnessed non-invasive fluorescence imaging to sequentially follow in vivo material-mass loss to model the degradation of materials hydrolytically (PEG:dextran hydrogel) and enzymatically (collagen). Hydrogel erosion rates in vivo and in vitro correlated, enabling the prediction of in vivo erosion of new material formulations from in vitro data. Collagen in vivo erosion was used to infer physiologic in vitro conditions that mimic erosive in vivo environments. This approach enables rapid in vitro screening of materials, and can be extended to simultaneously determine drug release and material erosion from a drug-eluting scaffold, or cell viability and material fate in tissue-engineering formulations.     

Copper oxide nanowires: a review of growth

Cuprous oxide (Cu(2)O) and cupric oxide (CuO) nanowires have started playing important roles in energy conversion devices and optoelectronic devices. Although the desired advanced properties have been demonstrated, these materials cannot yet be produced in large-bulk quantities in order to bridge the technological transfer gap for wider use. In this respect, the quest for the most efficient synthesis process which yields not only large quantities but also high quality and advanced material properties continues. This paper gives an extensive review of copper oxide nanowire (NW) synthesis by all methods and routes by which various researchers have obtained their nanomaterial. These methods are critically overviewed, evaluated and compared. Methods of copper oxide NW growth include wet-chemical methods based on pure solution growth, electrochemical and hydrothermal routes as well as thermal and plasma oxidation methods. In terms of advanced nanowire synthesis, the fast thermal method or direct plasma oxidation as well as the combined hybrid wet-chemical method in which copper hydroxide NWs are produced and sequentially transformed by plasma oxidation which produces Cu(2)O NWs are seen as the most promising methods to explore in the near future. These methods not only yield large quantities of NWs, but produce high quality material with advanced properties.     

Metal Ion-induced Gelation of High-concentration Graphite-like Crystalline Nanosheet Aqueous Suspensions

The stability and transformation of nanomaterial aqueous suspensions are essential for their applications. Preparation of high-concentration carbon nanomaterials suspensions remains challenging due to their nonpolar nature. Herein, 200 mg mL⁻¹ carbon nanomaterial aqueous suspensions are achieved by using graphite-like crystalline nanosheets (GCNs) with high hydrophilicity. Furthermore, these high-concentration GCN aqueous suspensions spontaneously transform into gels when induced by mono-, di-, and trivalent metal salt electrolytes at room temperature. Theoretical calculation of potential energy by DLVO theory reveals that the gelatinized GCNs is a new and metastable state between two usual forms of solution and coagulation. It is shown that the gelation of GCNs is due to the preferential orientation of nanosheets in an edge-edge arrangement, which differs from the case of solution and coagulation. High-temperature treatment of GCN gels produces metal/carbon materials with pore structures. This work provides a promising opportunity to create various metal/carbon functional materials.     

Graphene - a promising material for organic photovoltaic cells

As a promising two-dimensional nanomaterial with outstanding electronic, optical, thermal, and mechanical properties, graphene has been proposed for many applications. In this Progress Report we summarize and discuss comprehensively the advances made so far for applications of graphene in organic photovoltaic (OPV) cells, including that for transparent electrodes, active layers and interfaces layer in OPV. It is concluded that graphene may very likely play a major role in new developments/improvements in OPVs. The future studies for this area are proposed to focus on the following: i) improving the conductivity without comprising the transparency as a transparent electrode material; ii) controlling the sheet sizes, band structure and surface morphology for use as a electron acceptor material, and iii) controlling and improving the functionalization and compatibility with other materials as interface layer material.     

Predicting the mechanical properties of ordinary concrete and nano-silica concrete using micromechanical methods

By combining several materials with specific mechanical properties, new materials with unknown mechanical properties are obtained. Various experiments are required to determine the mechanical properties of the produced composite materials. Since conducting experiment processes is costly and time-consuming, comprehensive studies have been conducted in recent years to solve the problem. Fortunately, it is possible to easily predict the mechanical properties of composite materials without the need to construct them, by inspecting their constituent’s properties using micromechanical methods. Although various micromechanical methods have been presented so far, few of them yielded precise predictions of the properties of composite materials. Therefore, selecting a method suitable to predict the properties of composite materials is of much importance. In this study, some micromechanical approaches, including Hirsch, Hansen, Bache, Cavento, Mori–Tanaka, Eshelby, self-consistent, effective interface and double-inclusion models, were employed for the estimation of elasticity modulus and Poisson’s ratio of ordinary and nanomaterial concretes. The results obtained from the micromechanical methods were compared to those obtained from experimental tests. The obtained numerical results showed that Bache’s model is the most accurate micromechanics model for predicting the elastic mechanical properties of ordinary and nanomaterial concretes.