Metallography of ancient bronzes: Study of pre-roman metal technology in the Iberian Peninsula

The metallographic examination of 26 bronze archaelogical objects is discussed together with the routine developed for this. The main aim was to define the bronze technology known by the Vaccei (a Celtiberian culture from Spain). All of the objects studied here come from cremation graves and their chronologies cover the last five centuries BC. The older objects have reflected great skill in forging, which compensated for casting problems. These casting problems decreased gradually, but were still important until the Roman conquest, when a real advance in casting techniques can be recorded. Since we were not authorized to cut or mount the objects in plastic, we had to hold them in our bare hands and polish only their outer surfaces, which caused many scratches and other marks. This report also illustrates some of the technical problems that might arise when studying archaeological materials.     

Study of ancient lead materials: A gallo-roman sarcophagus—contribution of the electrolytic treatment to its restoration

The restoration of metallic archaeological artefacts needs the knowledge of ancient materials—their composition, their state of conservation and their manufacturing process—to avoid any inappropriate action in the restoration process. This paper is devoted to the study of a lead gallo-roman sarcophagus, found in a much corroded state after a long burial in a calcareous soil in the banks of the Rhône River at Lyon (France). From the metallographic observations, it was found that the lead sheets constituting the sarcophagus have been directly cast on a table covered with a bed of sand. In addition, the presence of a thick corrosion layer consisting of lead oxide, lead carbonates and some important penetrations of PbO in the metal explain the loss of lead ductility and the important brittleness of this ancient material. The mechanism of formation and growth of this PbO layer in a carbonated medium was studied using electrochemical experiments and metallographic observations. Finally, the comprehensive study of this complex material consisting of lead metals, a PbO/lead carbonate layer and some compounds of the soil allowed the setting up of a restoration process based on an electrochemical reduction method.     

Study on the inhibiting behavior of AMT on bronze in 5% citric acid solution

The corrosion behavior of bronze in the presence of 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) has been investigated in 5% citric acid by electrochemical measurements such as potentiodynamic polarization method and electrochemical impedance spectroscopy (EIS). It has been revealed that AMT is a good inhibitor for bronze. Both cathodic process and anodic process on bronze treated with AMT were different from that on the bronze without AMT treatment. Fourier transform infrared (FTIR) analysis was carried out to characterize the protective film, which revealed that the composition of the protective film was polymeric Cu(I)-inhibitor complex. AMT acted as bidentate ligand through the aminic nitrogen atom and the closed ring nitrogen in the complex.     

Influence of the nature of microconstituents on the tensile properties of a zinc-based alloy and a leaded-tin bronze at different strain rates and temperatures

An attempt has been made to study the influence of the nature of microconstituents, strain rate and test temperature on the tensile properties of a zinc-based alloy (ZA 27). The properties of the alloy have been compared with those of a (leaded-tin) bronze (SAE 660) under similar test conditions. In the latter case, one of the phases (lead) has rather poor compatibility with the matrix. Properties such as hardness, density and electrical conductivity of the alloys have also been measured. The microstructure of the zinc-based alloy revealed primary α-dendrites surrounded by the eutectoid α+η in the interdendritic regions. The metastable ε phase was also present. The bronze revealed primary α-dendrites together with the Cu–Sn intermetallic in the interdendritic regions. Discrete particles of lead were also observed in the microstructure of the bronze. Increasing test temperature caused a reduction in the ultimate tensile strength (UTS) and an increase in the ductility of the alloys, the zinc-based alloy being much more influenced than the bronze. Higher strain rates revealed improved strength and percentage elongation in which the zinc-based alloy was once again influenced more than the bronze. A comparison of the tensile properties revealed the UTS of the zinc-based alloy to be higher than that of the bronze at lower test temperatures while the trend reversed at higher temperatures. However, the percentage elongation of the former was always higher. Tensile fractured surfaces revealed the occurrence of material failure by a mixed mode, i.e. ductile and brittle type. The bronze specimens exhibited microcracking along the lead/matrix interfacial regions at low test temperatures. Fracture of lead was also observed in this case. However, this tendency was somewhat suppressed at higher test temperatures. The contribution of ductile fracture in the case of the zinc-based alloy was more than the bronze in general, whose extent increased at higher test temperatures. Coarsening of the dimples was another observation made at elevated test temperatures in the case of the zinc-based alloy. The behaviour of the alloys has been explained in terms of their microstructural and fractographic features. An attempt has also been made to understand the mechanisms of material failure. This revised version was published online in November 2006 with corrections to the Cover Date.     

Steel making in the ancient Korean Kingdom of Koguryo

Five iron artifacts excavated from the same spot in a military fortress of the former Korean kingdom, Koguryo (37 BCE–668 CE), have been metallographically examined. The result shows that they comprise two pieces of white cast iron, one piece of wrought iron and two pieces with microstructures consisting of high C steel buried in white cast iron or white cast iron buried in high C steel. This provides direct material evidence of both white cast iron and wrought iron being combined to form steel. This article is to present the detailed account of metallurgical microstructures observed in the rare archaeological evidence of the unique ancient steel making process involving liquid cast iron.     

Experimental and theoretical studies of palygorskite clays

We have studied the structure and properties of palygorskite clays. A structure analysis was performed using two different models to reproduce the monoclinic and orthorhombic lattices, using the atomic positions and cell parameters of palygorskite structure suggested by several authors, we simulated structures using Molecular Dynamics and Quantum Mechanics. Modifications on the structure and elemental atom changes were made to obtain more stable configurations. X-ray diffraction patterns and high resolution electron microscopy images from simulated structures were compared with experimental results. It could be observed that orthorhombic model shows a better fitting than monoclinic models. These results might help to understand many of the properties of archaeological pigments, such as, Maya Blue, in which palygorskite clay was the main component.     

Investigation of multilayer silicon structures with buried iron silicide nanocrystallites: growth, structure, and properties

The growth of nanosize islands of iron silicides on Si(100) substrates and epitaxial silicon overgrowth atop them have been studied by low energy electron diffraction and reflectance high energy electron diffraction methods. The near optimal formation conditions of iron silicide islands with high density and minimal sizes have been determined by using of atomic force microscopy. Multilayer (8-10) monolithic structures with buried iron silicide nanocrystallites have been grown after the definition of monocrystalline burying conditions of iron silicides nanocrystallites in silicon lattice. The structure of buried nanocrystallites has been studied in multilayer monolithic heterostructures by high resolution transmission electron microscopy. It was established that in multilayer samples the majority of nanocrystallites have beta-FeSi2 structure, but some of them have gamma-FeSi2 structure. It was observed an influence of additional annealing at 850 degrees C on the morphology and structure of nanocrystallites. By means of deep level transient spectroscopy data one and two trap levels have been observed in multilayer structures (without and with additional annealing, respectively). Photoluminescence spectra have been studied at 4.2 K and the causes of its absence from buried beta-FeSi, NC have been analyzed.     

A study of defects and impurities in doped detonation nanodiamonds by EPR,Raman scattering,and XRD methods

Samples of detonation nanodiamonds modified during the synthesis by adding doping elements in various ways have been studied by spectroscopic methods (electron paramagnetic resonance, Raman scattering, and X-ray diffraction). For the first time, the presence of P1 centers in detonation nanodiamond crystals has been indirectly demonstrated. The authors discuss the nature and distribution of spins as observed by the electron paramagnetic resonance, the composition of phases and size of the coherent scattering region, and crystal density (calculated by the X-ray method) of the detonation nanodiamond samples at hand.     

Physical Properties of NaNbO3–A2+TiO3and NaNbO3–A2+Nb2O6Solid Solutions

Solid solutions of compounds with the ilmenite, columbite, or potassium tungsten bronze structure in the perovskite compound NaNbO₃were studied. The observed property–structure–composition relations were used to choose promising compositions for designing new piezoelectric ceramics.     

Modifying the composition of a brass and bronze surface layer under a high power ion beam of a nanosecond duration

The change in the composition of the surface layers of brass LS59-1 and bronze BrOS10-10 under the action of a high power ion beam has been studied. Zinc depletion of the brass surface at a beam current density of j ～50 A/cm² is shown; zinc enrichment of the surface layer is observed at j > 150 A/cm², and a thin zinc layer is found to be formed across the entire surface. For bronze BrOS10-10, tin enrichment of the surface is registered only under a multiple effect of the beam at j >150 A/cm². Various mechanisms of modifying the elemental composition are considered.     

Dynamical behaviour of fine granular glass/bronze mixtures under vertical vibration

It has recently been reported that mixtures of fine equal-sized bronze and glass spheres separate into glass-rich and bronze-rich regions under sinusoidal vertical vibration [Burtally et al., Science 295, 1877 (2002)]. Here we report a study of these separation effects, varying both the bronze/glass size ratio and the composition of the mixture. For a wide range of mixtures we observe separation into bronze-rich and almost pure glass regions separated by extremely sharp boundaries. Either a bronze-rich region forms above a glass layer or a bronze-rich layer is sandwiched between two glass layers. Convection exists within each layer but does not act to cause mixing of the two regions. The separation into two regions is maintained even in the presence of a variety of spatial oscillations. The variations of behaviour with differing glass/bronze size ratios support the proposal of a differential air-damping separation mechanism, while experiments using a porous bottomed box indicate that separation requires air to be driven through the granular bed by the vibration.     

Chemical bath deposition and characterization of electrochromic thin films of sodium vanadium bronzes

Thin yellow-orange films of sodium vanadium oxide bronzes have been prepared from a sodium–vanadium solution (1:1) at 75 °C and pH = 3. The composition, structure and morphology of the films have been studied by XRD, IR spectroscopy, TG and SEM–EDX analyses. It has been established that the prepared films are a phase mixture of hydrated NaV₆O₁₅ (predominant component) and Na_1.1V₃O_7.9 with total water content of 10.58%.The sodium vanadium bronze thin films exhibit two-step electrochromism followed by color change from yellow-orange to green, and then from green to blue. The cyclic voltammetry measurements on the as-deposited and annealed vanadium bronze films reveal the existence of different oxidation/reduction vanadium sites which make these films suitable for electrochromic devices. The annealing of the films at 400 °C changes the composition, optical and electrochemical properties     

Bronzoid phases in the pseudo-binary system AxNbxW1−xO3 with A = K and Cs

The systems A_xNb_xW_1?xO₃, A = K, Cs, have been studied at 1200°C for compositions x < 0.5. Phases with intergrowth tungsten bronze (ITB) structure form for x ～ 0.08 – 0.12 and with hexagonal tungsten bronze (HTB) structure for x ～ 0.20 (with a small homogeneity range). The potassium system contains a tetragonal tungsten bronze (TTB)-type phase at x ～ 0.45 – 0.60 and cesium forms a pyrochlore phase at x～0.35 – 0.40. The alkali contents of the HTB and pyrochlore phases are considerably lower than those of phases prepared at 900°C. The tunnel occupancy is approximately the same, ～ 60 %, in the ITB, HTB and pyrochlore phases prepared at 1200°C. Two types of superstructures have been observed in the HTB-type crystals.     

Geophysical Investigations at Cairo’s Oldest,the Church of Abu Serga (St. Sergius), Cairo,Egypt

The results of an integrated geophysical survey at the archaeological site of Abu Serga church, Cairo, Egypt are presented and discussed. The aim was to investigate the ground conditions of the Church of Abu Serga (St. Sergius), the Cairo’s oldest, dated from 4th Century church, which is located at Qasr el-Shama in old Cairo in Egypt. In particular the objective is to study the subsurface geological structures at the location of the church, and to detect and possibly map any ancient remains concealed under the monument. The survey was conducted using two geophysical methods: the ground penetrating radar (GPR), which is a fully non-destructive method, and the electrical resistivity tomographies (ERTs). The usefulness of combining conventional geophysical mapping techniques and high resolution imaging methods in delineating shallow targets of archaeological interest at such complex archaeological sites, is studied. Ground penetrating radar time slices and 3D electrical tomography depth slices were used for the verification of specific anthropogenic anomalies, which were detected on the geophysical maps Processing of geophysical maps included filtering with the gradient and first derivative operators in the space domain and the upward continuation and Butterworth filters in the wave number domain. The integration of the geophysical measurements revealed that the present Crypt is not the original holy Crypt. The anomalous reflector is detected at depth of about 5 m below the sanctuary floor, in the form of buried ceiling of the original Crypt. The present Crypt is just a small low subterranean church belong to the 2nd century. High resistivity anomalies and distinct GPR signals were also observed deeper in the inner parts of the church. They are attributed to possible remains of ancient walls and surrounding tunnels, or other man-made structures concealed under the floor of the monument. The geophysical survey at Abu Serga church also demonstrates that the general features of the foundation soil are heterogeneous with abundance of fractures; the water table is very high at 1.8m below the sanctuary floors. The benefits of combined geophysical surveys in case of archaeological investigations at complex sites are highlighted.     

Microstructure development in Nb3Sn(Ti) internal tin superconducting wire

The authors have studied the phase formation sequences in a Nb₃Sn ‘internal tin’ process superconductor. Heat treatments were performed to convert the starting materials of tin, Ti–Sn, copper and niobium, to bronze and Nb₃Sn. Specimens were quenched at different points of the heat treatment, followed by metallography to identify the phases present and X-ray microtomography (XMT) to investigate the void volume and distribution. An unexpected observation of the microstructure development was the uphill diffusion of tin during the Cu–Sn reactive diffusion. Some defects likely to affect the superconducting performance of the wires were observed. Microscopy revealed the presence of a Ti–Sn intermetallic compound displacing the niobium filaments, and XMT revealed the formation of long pores in the longitudinal direction. Two types of pore formation mechanism, in addition to Kirkendall pores, are proposed. The phase and microstructure development suggests that low-temperature heat treatment (below 415 °C) will have significant influence on optimising the final superconducting properties.     

Thermoluminescence dating of archaeological artefacts from the Middle Neolithic,Bronze Age and the Roman Empire period

Thermoluminescence (TL) dating was applied for artefacts found near the small village of Michelstetten, Lower Austria. Settlements in this region can be traced hack a long time and, according to archaeologists, the discovered artefacts may be as old as 6000 years. A modified sample preparation technique based on the fine-grain method was developed. This technique results in a higher reproducibility and reduces the overall preparation time. For some artefacts the new information of the TL dating leads to an unforeseen re-interpretation of the archaeological age. Furthermore, an iron furnace from the period of the Roman Empire could be dated. For the first time, it was possible to estimate correctly the point of time of the burn-down of an ancient wooden house via an analysis of the house's clay plaster. The fire took place in the sixth century; this was confirmed by dating ceramic artefacts.     

Identification and Characterization of Buried Unpaired Cysteines in a Recombinant Monoclonal IgG1 Antibody

The heterogeneity in therapeutic antibodies arising from buried unpaired cysteines has not been well studied. This paper describes the characterization of two unpaired cysteines in a recombinant humanized IgG1 monoclonal antibody (referred to as mAb A). The reversed-phase high-performance liquid chromatography (RP-HPLC) analysis of mAb A samples showed three distinct peaks, indicating the presence of three species. The heterogeneities observed in the RP-HPLC have been determined to arise from unpaired cysteines (Cys-22 and Cys-96) that are buried in the V(H) domain. The Fab containing free thiols (referred to as "free-thiol Fab") and the Fab containing the disulfide (referred to as "intact Fab") of mAb A were generated through limited Lys-C digestion and purified with an ion exchange chromatography method. The binding of free-thiol Fab and intact Fab to its antigen was measured in a cell-based binding assay and an enzyme linked immunosorbent assay. The unpaired cysteines in the Fab of mAb A were found to have no significant impact on the binding to its target. Consistent with these Fab binding data, the enriched intact mAb A containing free thiols was determined to be fully active in a potency assay. The data reported here demonstrate that the redox status of cysteines is potentially a major source of heterogeneity for an antibody.     

唐代铜镜装饰艺术研究

目的对唐代铜镜的装饰艺术进行分析。方法通过对中国古代铜镜装饰发展历程的梳理,尤其对唐代铜镜的装饰题材、装饰主题、装饰铭文、装饰布局及构图等方面的研究,揭示中国古代铜镜装饰艺术对现代设计的借鉴作用。结论唐代铜镜纹样表现手段丰富、取材广阔、造型独特,是现代设计可借鉴的宝典,具有广泛的实用价值。     

Piezoelectric photoacoustic evaluation of Si wafers with buried structures

The piezoelectric photoacoustic evaluation of Si wafers with buried structures is studied experimentally and theoretically. In the experiment, the authors have detected and imaged the Sb-doped regions in a Si wafer covered by an epitaxial Si layer with about 10-mum thickness. In order to explain the experimental results, the one-dimensional multilayered model with discontinuous thermal impedance between the neighboring layers is used, and the expressions for the thermal and acoustic fields in the sample and PZT transducer are also presented. Moreover, numerical calculations in accordance with the practical experimental conditions have been carried out.     

三元青铜/环境界面上物质转移的化学行为

用模拟闭塞电池法(O.C.)研究了青铜在模拟环境介质0.028 mol·L-1NaCl 0.01 mol·L-1Na2SO4 0.016 mol.L-1NaHCO3中的局部腐蚀孔内或裂纹内的化学变化.通电32 h后闭塞区内溶液的Ph值由7.00降至5.02,与此同时Cl-和SO24-向闭塞区内迁移,其浓集倍数分别是6.31和2.93;测定了闭塞区内外Cu、Sn、Pb金属离子的浓度,据此计算出溶解因子fsn/Cu小于1,fpb/Cu大于 1,表明青铜中各元素选择性腐蚀的顺序为Pb＞Cu＞Sn,腐蚀速度Pb＞Cu＞Sn;用XRD分析了腐蚀产物的组成,解释了青铜文物表面腐蚀产物的分层现象,即从里到外为CuCl,CuCl和Cu2O,Cu的二价化合物.