Surface Decorations Research Articles

Authenticity of Benin metalworks evaluated by inductively coupled plasma mass spectrometry and lead isotope analyses

Two metal plaques and a cock statuette belonging to a private collection and stylistically consistent with the Royal Art of Benin (Nigeria) were investigated in order to verify their authenticity. The characterization of alloys and patinas were carried out by inductively coupled plasma mass spectrometry, optical microscopy, scanning electron microscopy and energy dispersion spectroscopy, and X-Ray diffraction spectrometry. Furthermore, thermal ionization mass spectrometry was used to assess the abundances of lead isotopes and to attempt a dating by the measurement of 210Pb/204Pb ratio.The results showed that all three artefacts were mainly composed of low lead-brass alloys, with relatively high concentrations of zinc, antimony, cadmium and aluminum in the solid copper solution. Microstructures were mostly dendritic, typical of as-cast brasses, and characterized by recrystallized non-homogeneous twinned grains in areas corresponding to surface decorations, probably due to multiple hammering steps followed by partial annealing treatments. The matrix was composed of a cored α-Cu solid solution together with non-metallic inclusions, lead globules and Sn-rich precipitates in interdendritic spaces. On the surface of all metalworks, both copper and zinc oxides, a non-continuous layer of sulphur-containing contaminants and chloride-containing compounds, were identified. The lead isotope results were consistent with brasses produced shortly before or after 1900CE. Overall, the data obtained by different techniques supported the hypothesis that the three artefacts were not authentic.

Hierarchical Supramolecular Cross-Linking of Polymers for Biomimetic Fracture Energy Dissipating Sacrificial Bonds and Defect Tolerance under Mechanical Loading.

Biological structural materials offer fascinating models how to synergistically increase the solid-state defect tolerance, toughness, and strength using nanocomposite structures by incorporating different levels of supramolecular sacrificial bonds to dissipate fracture energy. Inspired thereof, we show how to turn a commodity acrylate polymer, characteristically showing a brittle solid state fracture, to become defect tolerant manifesting noncatastrophic crack propagation by incorporation of different levels of fracture energy dissipating supramolecular interactions. Therein, poly(2-hydroxyethyl methacrylate) (pHEMA) is a feasible model polymer showing brittle solid state fracture in spite of a high maximum strain and clear yielding, where the weak hydroxyl group mediated hydrogen bonds do not suffice to dissipate fracture energy. We provide the next level stronger supramolecular interactions toward solid-state networks by postfunctionalizing a minor part of the HEMA repeat units using 2-ureido-4[1H]-pyrimidinone (UPy), capable of forming four strong parallel hydrogen bonds. Interestingly, such a polymer, denoted here as p(HEMA-co-UPyMA), shows toughening by suppressed catastrophic crack propagation, even if the strength and stiffness are synergistically increased. At the still higher hierarchical level, colloidal level cross-linking using oxidized carbon nanotubes with hydrogen bonding surface decorations, including UPy, COOH, and OH groups, leads to further increased stiffness and ultimate strength, still leading to suppressed catastrophic crack propagation. The findings suggest to incorporate a hierarchy of supramolecular groups of different interactions strengths upon pursuing toward biomimetic toughening.

Transport of nanoparticles across pulmonary surfactant monolayer: a molecular dynamics study.

Pulmonary nanodrug delivery is an emerging concept, especially for targeted lung cancer therapy. Once inhaled, the nanoparticles (NPs) acting as drug carriers need to efficiently cross the pulmonary surfactant monolayer (PSM) of lung alveoli, which act as the first barrier for external particles entering the lung. Herein, by performing molecular dynamics simulations, we study how inhaled NPs interact with the PSM, particularly focusing on the transport of NPs with different properties across the PSM. While hydrophilic NPs translocate directly across the PSM, transport of hydrophobic NPs is achieved as the PSM wraps them. Intriguingly, when hydrophilic NPs are decorated with lipid molecules (LCNPs), they are wrapped by the PSM efficiently with mild PSM perturbation. Moreover, the structure formed is like a vesicle, which will likely fuse with cell membranes to accomplish the transport of hydrophilic NPs into secondary organs. This behavior makes the LCNP a prospective candidate for pulmonary nanodrug delivery. Herein, the effects of the physical properties of LCNPs on their transport are investigated. Increasing the LCNP size promotes its wrapping by reducing the PSM bending energy. The binding energy that drives transport can be strengthened by increasing the lipid coating density and the lipid tail length, both of which also reduce the risk of PSM rupture during transport. These results should help researchers understand how to better use surface decorations to achieve efficient pulmonary entry, which may provide useful guidance for the design of nano-based platforms for inhaled drug delivery.

Investigation of Pottery from Different Neolithic Sites in Southeast Albania Using Various Analytical Techniques

In this paper we will consider the results of the investigation of ceramic shards from four Neolithic sites located in the south-east of Albania using different analytical methods. The sites of Vashtemi, Podgori, Dunavec and Maliq, situated at the plateau of Korca, represent the Neolithic culture at the different stages from Early Neolithic to Eneolithic. The application of EDXRF, micro-XRF, XRD and Optical Microscopy (OM) allowed us to collect data on the mineralogical and elemental composition of the ceramics and the materials used for the external decorations. The results indicate that coarse to medium coarse, non-calcareous clays were used for the ceramic manufacture in all the sites. Mineral inclusions rich in Si, Ca, K, and Fe were identified, some of which could have been intentionally added to the clays during the production process. The similarities of the elemental composition of the shards indicate that the ceramics in each site were prepared from different clay deposits that should have been close to each site. Minerals rich in Ca, Fe and Mn have been used respectively for the white, red and dark brown surface decorations, while bitumen has been applied after the firing in a black decoration.

Unraveling deformation mechanisms around FCC and BCC nanocontacts through slip trace and pileup topography analyses

Nanocontact loadings offer the potential to investigate crystal plasticity from surface slip trace emissions and distinct pileup patterns where individual atomic terraces arrange into hillocks and symmetric rosettes. Our MD simulations in FCC Cu and Al nanocontacts show development of specific dislocation interception, cross-slip and twin annihilation mechanisms producing traces along characteristic <011> and <112> directions. Although planar slip is stabilized through subsurface dislocation interactions, highly serrated slip traces always predominate in Al due to the advent of cross-slip of the surfaced population of screw dislocations, leading to intricate hillock morphologies. We show that the distinct wavy hillocks and terraces in BCC Ta and Fe nanocontacts are due to dislocation double-kinking and outward spreading of surfaced screw segments, which originate from dislocation loops induced by twin annihilation and twin-mediated nucleation processes in the subsurface. Increasing temperature favors terrace formation in BCCs whereas the enhancement of surface decorations in FCCs limits hillock definition. It is found that material bulging against the indenter-tip is a distinctive feature in nanocontact plasticity associated with intermittent defect bursts. Bulging is enhanced by recurrent slip traces introduced throughout the contact surface, as in the case of the strongly linear defect networks in FCC Al, and by specific twin arrangements at the vicinity of BCC nanocontacts. Defect patterning also produces surface depressions in the form of vertexes around FCC nanoimprints. While the rosette morphologies are consistent with those assessed experimentally in greater FCC and BCC imprints, local bulging promoted during tip removal becomes more prominent at the nanoscale.

Beneficial Effect of Surface Decorations on the Surface Exchange of Lanthanum Strontium Ferrite and Dual Phase Composites

Perovskites within the (La,Sr)(Fe,Co)O3 class of materials show variations in the oxygen stoichiometry depending on temperature and oxygen activity and can potentially be used as catalysts, electrodes in high-temperature solid oxide fuel cells, gas sensors or for oxygen transport membranes. These perovskites possess a mixed ionic and electronic conductivity (MIEC), which can be highly beneficial for the processes on oxygen electrode surfaces. The oxygen transport through a MIEC is determined by the rate of the oxygen exchange over the gas-solid interface and the diffusivity of oxide ions and electrons (or holes) in the bulk. The oxygen exchange process over the surface in general involves several reaction steps, O2 adsorption, dissociation, charge transfer and incorporation of ionic species. The Co-free end member of the material class; LSF (e.g. (La0.6Sr0.4FeO3-δ ) is fairly low cost and chemically stable in both mildly reducing and oxidizing atmosphere. The electronic conductivity is excellent (283 S/cm at 800 °C) but the ionic conductivity especially at low temperature is limited (0.014 S/cm, 800 °C). Due to these properties the material is a candidate for use in composite membranes in combination with a better ionic conducting material like CGO. Such systems are also excellent model systems for fundamental studies of the oxygen exchange process.The aim of this study is to characterize the oxygen transport properties of a dual-phase composite system as a function of temperature, and to elucidate the origin of the enhancement of the surface exchange reaction that has been reported to occur in such systems1by increasing the amount of ionic conductor. Additionally, the effect of surface decorations (desired) and impurities (undesired) on the surface exchange was studied to illustrate the importance of controlled conditions for the sample preparation and measurements. Electrical Conductivity Relaxation (ECR) was used to study the surface exchange reaction and the oxygen ion diffusion of single phase (La0.6Sr0.4)0.98FeO3-δ and dual phase composites of (La0.6Sr0.4)0.98FeO3-δ – Ce0.9Gd0.1O1.95 (LSF-CGO). From the relaxation curves, fitted by using Fick’s Laws of diffusion with appropriate boundary conditions, both the oxygen surface exchange coefficient (k ex) and the oxygen chemical diffusion coefficient (D chem) was derived. The results of ECR clearly show that the CGO surface is involved in the surface exchange reactions on the composite and that by increasing the fraction of CGO the surface exchange is significantly enhanced. The involvement of CGO in the surface exchange can arise from fast exchange in the triple phase boundaries and/or the spillover of oxygen ions from LSF to CGO, where they incorporate. Additional effects can also originate from the fact that LSF scavenges impurities from CGO and therefore activate the CGO surface for the surface exchange reaction as proposed by Druce et al. 2. This was separately studied by coating of the surface of the single phase LSF and the composite with different elements/oxides regarded as potential impurities. However, opposite to the trivial anticipation a strong positive influence of secondary phases (not normally considered to be good oxygen reduction catalysts) on the surface exchange coefficient was observed. For example depositing CaO/CaCO3 on the surface led to an enhancement of the oxygen incorporation rate for 3.4 times at 750 °C.The study concludes that the formation of a composite of MIEC and ionic conductor and controlled coating with a range of secondary phases on the surface (e.g. CaO, …) is highly beneficial for the oxygen reduction process.1. Hu, B.; Wang, Y.; Xia, C., J. Power Sources 2014, 269, 180-1882. Druce, J.; Kilner, J. A., J. Electrochem. Soc. 2014 , 161, F99-F104.

Enhancement of oxygen surface exchange on epitaxial La0.6Sr0.4Co0.2Fe0.8O3-δ thin films using advanced heterostructured oxide interface engineering

Engineering of a novel heterostructured oxide interface was used to enhance the oxygen surface exchange kinetics of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF113) thin films. A single-layer decoration of mixed (LaSr)2CoO4±δ (LSC214) and La1-xSrxCoO3-δ (LSC113) and a double-layer decoration of stacked LSC214 and LSC113 grown on the LSCF113 markedly enhanced the surface exchange coefficients of the LSCF113 by up to -1.5 orders of magnitude relative to the undecorated LSCF113. It is hypothesized that two different types of surface decorations can enable Sr segregation at the interface and surfaces of LSC113 and LSC214, leading to enhancement of the oxygen surface exchange kinetics of decorated LSCF113.

Orthogonal Click Conjugation to the Liposomal Surface Reveals the Stability of the Lipid Anchorage as Crucial for Targeting.

Synthetic access to multiple surface decorations are a bottleneck in the development of liposomes for receptor mediated targeting. This opens a complex multiparameter space, exploration of which is severely limited in terms of sample numbers and turnaround times. Here, we unlock this technological barrier by a combination of a milligram-scale liposome formulation using dual centrifugation and orthogonal click chemistry on the liposomal surface. Application of these techniques to conceptually new amphiphilic compounds, which feature norbornene and alkyne groups at the apex of sterically stabilizing, hyperbranched polyglycerol moieties, revealed a particular influence of the membrane anchor of functional amphiphiles. Folic acid residues clicked to cholesterol-based amphiphiles were inefficient in folate-mediated cell targeting, while dialkyl-anchored amphiphiles remained stable in the liposomal membrane and imparted efficient targeting properties. These findings are of specific importance considering the popularity of cholesterol as a lipophilic anchor.

Electronic structure and topological features of tin-based binary nanosheets and their hydrogenated/fluorinated derivatives: A first-principles study

Utilizing first-principles calculations, we have investigated the structural, electronic and topological properties of binary SnSi and SnGe nanosheets as well as their H-/F-derivatives. It is found that all these systems have chair-like buckled configurations with robust structural stabilities. Unlike the elemental group-IV sheets, SnSi and SnGe sheets are narrow-band-gap semiconductors, which have a gapped Dirac cone with massive Fermions. Under the strains, a direct-to-indirect band gap transition and a semiconductor-to-metal transition would occur in these systems. Although these binary systems are trivial band insulators with ℤ2=0, their topological features can be altered by the surface decorations. Particularly, the fluorinated SiGe sheet becomes a topological insulator with ℤ2=1, and such non-trivial state can also be found in the strained fluorinated SnSi and hydrogenated SnGe sheets. Large non-trivial SOC band gaps of 0.09–0.17eV are obtained in these 2D topological insulating systems, which will be beneficial for realizing the room-temperature quantum spin Hall effect. Our study demonstrates that binary Sn-based nanomaterials possess tunable electronic and topological properties, which have potential applications in low-power nano-electrics and devices.

Teichoic Acid Polymers Affect Expression and Localization of dl-Endopeptidase LytE Required for Lateral Cell Wall Hydrolysis in Bacillus subtilis.

In Bacillus subtilis, the dl-endopeptidase LytE is responsible for lateral peptidoglycan hydrolysis during cell elongation. We found that σ(I)-dependent transcription of lytE is considerably enhanced in a strain with a mutation in ltaS, which encodes a major lipoteichoic acid (LTA) synthase. Similar enhancements were observed in mutants that affect the glycolipid anchor and wall teichoic acid (WTA) synthetic pathways. Immunofluorescence microscopy revealed that the LytE foci were considerably increased in these mutants. The localization patterns of LytE on the sidewalls appeared to be helix-like in LTA-defective or WTA-reduced cells and evenly distributed on WTA-depleted or -defective cell surfaces. These results strongly suggested that LTA and WTA affect both σ(I)-dependent expression and localization of LytE. Interestingly, increased LytE localization along the sidewall in the ltaS mutant largely occurred in an MreBH-independent manner. Moreover, we found that cell surface decorations with LTA and WTA are gradually reduced at increased culture temperatures and that LTA rather than WTA on the cell surface is reduced at high temperatures. In contrast, the amount of LytE on the cell surface gradually increased under heat stress conditions. Taken together, these results indicated that reductions in these anionic polymers at high temperatures might give rise to increases in SigI-dependent expression and cell surface localization of LytE at high temperatures. The bacterial cell wall is required for maintaining cell shape and bearing environmental stresses. The Gram-positive cell wall consists of mesh-like peptidoglycan and covalently linked wall teichoic acid and lipoteichoic acid polymers. It is important to determine if these anionic polymers are required for proliferation and environmental adaptation. Here, we demonstrated that these polymers affect the expression and localization of a peptidoglycan hydrolase LytE required for lateral cell wall elongation. Moreover, we found that cell surface decorations with teichoic acid polymers are substantially decreased at high temperatures and that the peptidoglycan hydrolase is consequently increased. These findings suggest that teichoic acid polymers control lateral peptidoglycan hydrolysis by LytE, and bacteria drastically change their cell wall content to adapt to their environment.

Determination of parameters for local electrolytic treatment of corroded lead and lead-tin alloys

Abstract A new electrolytic pencil (composed of a pseudo-electrode and a counter electrode contained in a nozzle enclosed by a microporous sponge pad in contact with a metallic object) was tested on its capacity to reduce the lead carbonates, which develop on lead and lead-tin objects exposed to corrosive organic acid vapors. Pure lead and two lead-tin alloys (5 and 50% of tin) were considered. Treatment parameters were defined by an electrochemical study on artificially corroded samples. Lead carbonate reduction is usually carried out at −1.3 V versus a mercury saturated sulfate electrode (SSE). In the case of lead-tin alloys, a second reaction exists in the cathodic field corresponding to tin oxide (SnO 2 ) reduction, which starts at −1.7 V/SSE. Thus, it is possible to realize a selective treatment, reducing only lead carbonates. The potential value depends on the reference electrode and the ohmic drop induced by the configuration of the electrolytic pencil, the Pleco. The pseudo-reference electrode can be a glassy carbon electrode (GC) or a tungsten electrode (W). Treatment parameters were determined with the Pleco using the two above-mentioned reference electrodes: lead carbonate reduction is at −1.5 V/GC or −1.4 V/W. Reduction of lead carbonates was done successfully with Pleco: overall thickness of lead carbonates was reduced without affecting their original shape, thereby ensuring the preservation of surface details and decorations. This local treatment was also tested on the interface between the metal and cord parts of seals attached to parchment: the cords are better protected while the other parts of the seals will undergo electrolytic treatment by immersion. Corrosion products were reduced without degrading the threads. Finally, a reduction treatment was performed on a lead seal belonging to the Departmental Archives of Loire-Atlantique (France).

Small is beautiful: Surprising nanoparticles

In the preparation of nanoparticles for drug delivery, it is well known that their size as well as their surface decorations can play a major role in interaction with living media. It is less known that their shape and internal structure can interplay with cellular and in vivo fate. The scientific literature is full of a large variety of surprising terms referring to their shape and structure. The aim of this review is to present some examples of the most often encountered surprising nanoparticles prepared and usable in the pharmaceutical technology domain. They are presented in two main groups related to their physical aspects: 1) smooth surface particles, such as Janus particles, “snowmen”, “dumbbells”, “rattles”, and “onions” and 2) branched particles, such as “flowers”, “stars” and “urchins”. The mode of preparation and potential applications are briefly presented. The topic has a serious, wider importance, namely in opportunity these structures have to allow exploration of the role of shape and structure on the utility (and perhaps toxicity) of these nanostructures.

"Flash" preparation of strongly coupled metal nanoparticle clusters with sub-nm gaps by Ag+ soldering: toward effective plasmonic tuning of solution-assembled nanomaterials.

Noble metal nanoparticle oligomers are important in applications including plasmonics, catalysis, and molecular sensing. These nanostructural units featuring abundant inter-particle junctions are helpful for a physical/chemical understanding of structure-activity relationships of self-assembled metamaterials. A simple, rapid, and potentially general strategy for the preparation of monodisperse nanoparticle clusters in a homogeneous solution is highly desired for fundamental research toward liquid metamaterials and chemical/biological applications, but this is however very challenging. Here we report an Ag+ soldering strategy to prepare strongly coupled plasmonic (Au) and catalytic (Pt, Au@Pd (Au core with a Pd shell)) nanoparticle clusters almost instantly (<1 min) in a solution without special synthetic efforts, complicated surface decorations, or structure-directing templates. The resulting clusters are isolatable by agarose gel electrophoresis, resulting in mechanically stable products in high purity. The optical extinctions of Au nanodimers (the simplest and most basic form of a coupled structure) exhibit prominent longitudinal plasmonic coupling for nanoparticles down to 13.3 nm in diameter. Theoretical simulations attribute the strong coupling to the existence of a sub-nm gap (c.a. 0.76 nm) between soldered particles, suggesting an ideal (stable, soluble, monodisperse, and weakly passivated) substrate for surface enhanced Raman scattering (SERS) applications.

ChemInform Abstract: III—V Nanowires: Synthesis, Property Manipulations, and Device Applications

AbstractReview: 61 refs.

Wood flour modified by hierarchical Ag/ZnO as potential filler for wood–plastic composites with enhanced surface antibacterial performance

In order to extend application potential of wood–plastic composites (WPC) in interiors with respect to hygienic requirements, wood flour (WF) was modified by nanosilver, nanostructured ZnO and hybrid nanostructured Ag/ZnO surface decorations. A microwave assisted solvothermal synthesis method was employed starting from soluble precursors. Composition of source chemicals and synthesis protocol were intentionally varied to prepare different materials and elucidate the reaction mechanism. Obtained modified wood flour were compounded into a model PVC matrix to assess their antibacterial performance. The surface antibacterial activity was tested according to ISO 22196: 2007 (E) standard. Single silver or ZnO modified WF have significantly lower efficiency than hybrid Ag/ZnO decorating the surface of WF particles. A simple variation of the synthesis method by additional ammonia precipitation step increased largely the performance of the material and excellent efficiency comparable with contemporary medical grade materials was achieved, suggesting the great application potential of investigated systems in WPC-based materials.

Surface Decorations of Al-Cu-Fe and Al-Cu-Co Single Quasicrystals

We studied surface decorations of faceted icosahedral Al Cu Fe and decagonal Al Cu Co single quasicrystals by the scanning electron microscopy using primary and secondary electrons. Both types of single quasicrystals exhibited decorations on their facets, however the character of the decorations was totally di erent. Three kinds of decorations has been developed. On icosahedral Al60Cu26Fe14 quasicrystals we found three kinds of decorations: cellular, cavity type and fractal-like. There was no evident di erence in chemical composition between the inner dodecahedra and the decorations of all types. Surface decorations found on decagonal Al73.5Cu17.5Co9 quasicrystals formed a kind of irregular dendritic stars on the separate bright islands.

Catalysts for selective propane oxidation in the presence of carbon monoxide: Mechanistic aspects

The competitive combustion of propane and carbon monoxide was investigated with regard to its selectivity for propane oxidation. Based on variations in the sol–gel synthesis and the composition, the TiCrOx catalysts were optimized. Specifically, the addition of small amounts of cerium led to a catalyst, which converted 89% propane at 375°C but no carbon monoxide. The origin of this excellent and unusual selectivity has been investigated. The method of choice was diffuse reflectance infrared Fourier transformed spectroscopy (DRIFTS), which allowed recording adsorbed species on the catalysts surface. Hopcalite was taken as reference catalyst due to its selectivity (although opposite to TiCrOx) for the combustion of carbon monoxide in the presence of hydrocarbons. The spectroscopic investigations showed that carbon monoxide is linearly adsorbed on Cu+ at lower temperatures and formed carbonates at higher temperatures, whereas propane formed no detectable adsorbed species on hopcalite. The TiCrOx catalyst formed formate species with carbon monoxide above 250°C and carboxylates with propane above 150°C. The mixture of propane and carbon monoxide led to the formation of both species. By the addition of oxygen to the gas feed, only propane formed adsorbates on the catalysts surface, whereas CO seemed not to interact with the surface. Pre-adsorbed oxygen probably inhibits the adsorption of carbon monoxide but is not necessary for propane activation. The formation of carboxylates from propane also takes place in the absence of molecular oxygen, pointing to a Mars-van-Krevelen-like mechanism, in which lattice oxygen is involved in the oxidation process. A physical mixture of TiO2 and Cr2O3 showed no catalytic activity, and spectroscopic investigations showed no adsorbates on the sole oxides. Since only anatase and eskolaite could be identified in the powder diffraction patterns of the catalysts, a third phase has to be responsible for the propane oxidation, most likely surface decorations or solid solutions of the metal ions.

III–V Nanowires: Synthesis, Property Manipulations, and Device Applications

III–V semiconductor nanowire (NW) materials possess a combination of fascinating properties, including their tunable direct bandgap, high carrier mobility, excellent mechanical flexibility, and extraordinarily large surface‐to‐volume ratio, making them superior candidates for next generation electronics, photonics, and sensors, even possibly on flexible substrates. Understanding the synthesis, property manipulation, and device integration of these III–V NW materials is therefore crucial for their practical implementations. In this review, we present a comprehensive overview of the recent development in III–V NWs with the focus on their cost‐effective synthesis, corresponding property control, and the relevant low‐operating‐power device applications. We will first introduce the synthesis methods and growth mechanisms of III–V NWs, emphasizing the low‐cost solid‐source chemical vapor deposition (SSCVD) technique, and then discuss the physical properties of III–V NWs with special attention on their dependences on several typical factors including the choice of catalysts, NW diameters, surface roughness, and surface decorations. After that, we present several different examples in the area of high‐performance photovoltaics and low‐power electronic circuit prototypes to further demonstrate the potential applications of these NW materials. Towards the end, we also make some remarks on the progress made and challenges remaining in the III–V NW research field.

中国古代泥塑彩绘制作工艺探讨

探讨中国古代泥塑彩绘传统工艺兼具文化遗产传承和文物保护方法研究的双重意义。本文通过文献、史料和实物调查，对泥塑彩绘制作工艺的发展过程进行了梳理。根据泥塑彩绘的土料、掺加料、成型方式、构架，表面修饰、颜料、装饰等方面探讨了泥塑彩绘各项工艺技术的起源。认为中国古代泥塑彩绘工艺的发展大体可以分为三个阶段，约6000年前的原始起步阶段，距今约3000~6000年的初级发展阶段，以及从2000多年前开始的高度发展阶段。中国古代泥塑彩绘制作中对土料等原料的一系列预处理，构件的模块化设计和模制成型，成品的精确组装和精致修饰等，在当时都应是世界领先的工艺技术，值得我们弘扬和保护。The aim of this study was to illustrate the significance of handicraft techniques of the ancient Chi-nese painted clay sculpture in both the cultural heritage inheritance and the conservation metho-dology research. The historical development of the handicraft techniques of the painted clay sculpture were summarized and documented through extensive literature review and actual sam-ple investigations. The origins of those handicraft techniques were discussed by looking at raw soil materials, mixing materials, the ways of molding, architecture, surface modification, applied pigments as well as surface decorations. Historically, the development of handicraft techniques of the ancient Chinese painted clay sculpture could be divided into three stages: the starting stage beginning around 6000 years ago, the early-development stage from 6000 years ago to 3000 years ago, and the well-development stage beginning from around 2000 years ago. Among the various handicraft techniques, the pretreatments of the raw materials including soil, modular design and molding of the parts, precise assembly of the parts as well as delicate decorations on the sculpture, etc., were thought to be world-leading at that time. Nowadays, more efforts are needed to be put on promotion, broadcasting as well as further development of the handicraft techniques.

Surface and size effects on the charge state of NV center in nanodiamonds

Electronic structures and stability of nitrogen–vacancy (NV) centers doped in nanodiamonds (NDs) have been investigated with large-scale density functional theory (DFT) calculations. Spin polarized defect states are not affected by the particle sizes and surface decorations, while the band gap is sensitive to these effects. Induced by the spherical surface electric dipole layer, surface functionalization has a long-ranged impact on the stability of charged NV centers doped in NDs. NV− center doped in DNs is more favorable for n-type fluorinated diamond, while NV0 is preferred for p-type hydrogenated NDs. Therefore, surface decoration provides a useful way for defect state engineering.