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To filter out the phase noise of the $\Phi $ -OTDR system, a method based on empirical mode decomposition and Pearson correlation coefficient fusion (EMD-PCC) is proposed. First, the EMD-PCC method is simulated. The experimental results show that the SNR increases from 7.32 dB to 13.68 dB. Second, the beat signal detected by the $\Phi $ -OTDR system is demodulated by the I/Q quadrature demodulation method. Finally, the phase signal is decomposed by empirical mode decomposition to obtain the modal function and residual component. The Pearson correlation coefficient with the phase signal is calculated. Then, the threshold value is 0.4–1.0. The modal function within the threshold is superimposed with the residual component signal. In this paper, the experimental verification of PZT analog disturbance signal frequencies of 200 Hz, 300 Hz, 400 Hz and 500 Hz is performed. Then, wavelet denoising and EMD-soft denoising are compared with EMD-PCC denoising. Experimental results show that the proposed method can accurately restore the disturbance signal. The experiment of sawtooth disturbance signal frequencies of 400 Hz and 500 Hz verifies the applicability of the algorithm and shows that the method is suitable for other arbitrary forms of disturbance signals. The $\Phi $ -OTDR system has an important application in the field of oil and gas exploration. This method provides a good theoretical basis for the exploration field.

To improve the signal-to-noise ratio (SNR) of vibration location information in $\Phi $ -OTDR system, a variable step size normalized least mean square (VSS-NLMS) denoising method is proposed in the article. First, the mathematical principle of VSS-NLMS method is established. The method can adaptively filter the input signal and adjust the parameters. It can also update the step factor adaptively. The simulation results show that the SNR of this method is improved from −1.16 dB to 12.01 dB. Second, a heterodyne coherent optical system is built. After the detected beat signal is demodulated by $\textit {I/Q}$ quadrature demodulation, the amplitude signal and phase signal of the Rayleigh backscattered light are acquired. The amplitude signal determines the location information and the phase signal determines the vibration signal. Finally, the wavelet denoising method, the empirical mode decomposition soft threshold (EMD-soft) denoising method and the variational mode decomposition nonlinear wavelet threshold (VMD-NWT) denoising method are compared with the VSS-NLMS denoising method in the experiment. The experimental results show that the location information SNR of the VSS-NLMS denoising method is improved to 59.31 dB, 46.81 dB, 50.14 dB, 34.00 dB and 67.09 dB for 5 groups of 100 Hz - 500 Hz vibration events at the location of the 10.14 km sensing fiber. At the same time, the vibration signals of 5 groups are demodulated. This method has laid a foundation for the application of oil and gas pipelines.

To evaluate the detection and recognition ability of infrared imaging systems in the field, it is necessary to establish a high-precision infrared simulation system that can generate multiple object types. Therefore, a dual-closed-loop temperature control method and system for high-precision infrared objects based on dual sensors are developed. First, the heat exchange model of infrared target system is established by studying the mechanism of infrared radiation. Second, an ADT7420 digital sensor and a Pt100 analogue sensor are used as dual sensors, in which the temperature measurement results of the digital sensor are used as a coarse reference, and then the temperature measurement results of the analogue sensor are used to achieve fine adjustment. Third, a predictive proportional-integral- derivative (PID) control algorithm for real-time tuning of online parameters is designed in detail, and online information control based on dual sensors is realized once. The temperature is calibrated based on a high-precision infrared thermal imager to realize secondary control of the temperature information, thereby forming internal and external dual-closed-loop temperature measurement control. The specific performance is as follows: in the inner closed loop, the main control computer realizes the temperature control of the heater by controlling the target element controller, and the temperature control situation is displayed on the main control computer. In the outer closed loop, the temperature data of each target element are collected by a high-precision infrared camera, and the target system is calibrated in real time by the master control computer. Finally, the system is verified by comprehensive experiments. The results show that the applicable temperature range of the system is −15 ~ +50 °C. The temperature control accuracy is ≤ 0.5 °C, and the repeatability error is less than 1.5% within the ambient temperature ±10 °C. The system control period is less than 60 s when the temperature difference is 2 °C. The system can simulate large-area and high-precision infrared targets in the field environment. It can be remotely controlled by computer terminals. Point or surface objects can be generated as needed in the system. At the same time, the system can continue to expand the number of target elements to achieve larger and more complex object targets, which has important engineering application value.

Man-made ancient Chinese barium copper silicate pigments: Chinese (Han) Purple, BaCuSi2O6; Chinese (Han) Blue, BaCuSi4O10; Chinese Dark Blue, BaCu2Si2O7(in summary called Chinese blues), and platelet-like crystals of BaSnSi3O9were detected on mural paintings of a tomb in Luoyang City, Henan Province, China, dated to Western Han Dynasty (206 BC–8 AD). The pigments of the LY01 and LY02 samples were analyzed by archaeometrical methods: powder X-ray diffractometry (XRD), scanning electron microscopy (SEM–EDX) and micro-Raman spectroscopy. While the artificial nature of the ancient barium copper silicates was undoubted, the synthetic or mineral origin of BaSnSi3O9of these murals had to be clarified. Involvement of the rare mineral pabstite Ba(Sn,Ti,Zr)Si3O9from the Tian Shan mountains could be ruled out due to absence of Ti and Zr in the elemental composition. Tin compounds as admixtures to the lead minerals—the latter required as flux additive for the preparation of the Chinese blues—or tin admixtures to pristine barium starting minerals could be excluded, as well as the use of tin containing mineral mushistonite (CuSn(OH)6), primarily intended to be applied as copper source. Related to the findings for the production of Egyptian Blue (CaCuSi4O10), bronze or bronze scrap including also corroded material was used intending copper recycling. For the synthesis of the Luoyang Chinese blues only low amounts of bronze or bronze scrap were required providing the additional advantage to form in presence of air a tin/lead oxide flux with lowered vitrification temperatures and viscosities. This marked the advent of an ‘innovative production technology’ avoiding addition of large amounts of lead minerals as an effective lead-only flux. Despite of the chemical similarity to production of Egyptian Blue, the tin/lead based developments for the Chinese blues were anticipated to be independent excluding technology transfer from ancient Egypt. For further substantiation of the appearance of pabstite in the Luoyang Chinese blues a contemporary independent synthesis was sought, carried out under conditions similar to those of the barium copper silicate syntheses (1000 °C, but absence of a flux) starting from cassiterite (SnO2), quartz (SiO2) and witherite (BaCO3).

Red discolorations are an effloresce phenomenon detect on the surface of stone objects and considered as damage factor in both esthetic and conservation points of view. It is very difficult to remove and seldom report about their weathering mechanism. Recently, numerous of red discolorations have affected the limestone objects of Lingyan Temple in Shandong province, one of the most important building materials in China. In order to set up the appropriate conservation remedy, it is essential to identify the origin, characteristics, composition, and the formation process of red discolorations. Several analytical and investigation techniques, such as X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), Micro-Raman spectroscopy (Raman), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) were used to better understand the red discolorations. The results demonstrated that the discolorations on limestone surface have been caused by carbonic acid weathering process. The red discolorations consisted mainly of kutnohorite (Ca(Fe,Mg,Mn)CO3) and iron oxides. They showed tabular, lamellar, and granular morphologies, which originated from the in situ carbonic acid weathering of kutnohorite. After rainfall, the Ca, Mg, Mn ions with relatively high solubility were primarily leached from carbonatite phases. It was resulting in the sedimentation of red iron oxides through a chemical reaction and physical adhesion. Based on those analyses, a chelating agent (ethylenediamine tetraacetic acid disodium salt) was chosen to remove theses red discolorations on the stone object.

The spontaneous degradation of pigments in painting may occur depending on environment, especially the surrounding condition of high humidity and soluble salts. Even some of these are well studied, more investigations are still in need for heritage science. Paint cross sections from Vairocana Statue in Dazu Rock Carvings, one of World Cultural Heritage, Chongqing, China are studied by optical microscopy (OM), Raman spectroscopy (Raman) and mapping, and scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM–EDS). Ultramarine blue, emerald green, synthetic atacamite, vermilion, red lead, gold foil, orpiment, cerussite, gypsum and barite are identified as pigments. Moreover, lavendulan (NaCaCu5(AsO4)4Cl·5H2O) and mimetite (Pb5(AsO4)3Cl) are degradation products of emerald green (Cu(C2H3O2)2·3Cu(AsO2)2) and cerussite(PbCO3) originally used as green pigment with mixture. These secondary products is formed via multistep progresses as degradation of emerald green and cerussite, oxidation of arsenite ((AsO2)-), migration of arsenate ((AsO4)3-) and precipitation reaction of these ions with other necessary ions from environmental conditions. Based on the pigment and paint layer stratigraphy analysis, the paintings of the statue have been executed at least four times and the most recent may be after 1850s. The formation of lavendulan give rise to a highlight for identification of green copper-arsenic containing pigments and characterization of degradation in complex conditions.

Compared with other wall paintings, tomb murals are rarely and have been most seriously damaged by natural weathering, erosion of bacteria and vandalism. Traditional identification methods are time-consuming, laborious, and confined to the visible light range, which mainly relies on expert's experience, analogy and visual color. This calls for new recording methods for mural site protection, relics restoration and repairs. Hyperspectral imaging can capture pictures of spectral range from visible to near infrared light, which render visual enhancement of faded tomb murals. This paper presents a method that can extract faded mural pattern from the hyperspectral images of mural, taking the leaf-like mural patterns in typical Tang dynasty tomb in China as an example. In the method, the faded leaf-like patterns are highlighted through normalization of sensitive spectral bands and extracted by density slice and masking on image space. The result shows that the method can extract the target pattern efficiently with the simple operations.

Honglvcai (also named red and green porcelain) was prosperous in Jin Dynasty (1115–1234 AD) and had played a pivotal role in ancient ceramic development history in China, connecting with former glazed pottery Tang Sancai and later polychrome porcelain like Wucai and Doucai, but little scientific analysis has been reported up until the present day. In this research, one precious sherd unearthed from Linshui (one major site of Cizhou kiln system) in Hebei province was adopted as specimen for compositional and micro-structural analysis. Optical microscope (OM), X-ray fluorescence spectrometry (XRF) and energy dispersive spectrometry (EDS) in association with scanning electron microscope (SEM) were employed for investigation of the multi-colour decors and black outline. The extensive data reveal that although high lead content has been detected by surface analysis and the iron-rich pigment particles do locate in the middle of the whole vitrified region, the black outline in fact belongs to high temperature fired under-glaze painted decoration, rather than the deceptive low temperature fired lead based over-glaze decor or the generally believed ‘sandwich’ (glazed twice) structure. Furthermore, a corresponding criterion then has been established for differentiation among three main decorating methods, especially for the puzzling ‘sandwich’ effect scenario. Moreover, once this ongoing vexed debate over the nature of the black decoration in Cizhou kiln system has been clarified, it is then reasonable to deduce that, from idealistic and technical point of view, there is no difference between producing prototype like this sherd and real Doucai in Ming dynasty (1365–1644 AD) except for the types of under-glaze pigment. Overall, all these results together firstly provide realising scientific proofs for the origin of Doucai.

This study devised an effective method for the direct production of hydroxyfatty acids (HFAs) from free fatty acids (FFAs) using Escherichia coli. By employing fatty acid hydroxylase P450BM3 and glucose dehydrogenase (GDH) to convert FFAs to HFAs, high-specificity production of C12 HFAs was achieved. By further knocking out the endogenous fadD gene of E. coli, an engineered strain capable of producing 702.3 mg/L C12 HFA was finally obtained, accounting for 92.9% of the total HFAs production, representing a higher titre reported in shake flask so far. This study provides an attractive strategy for increasing HFAs production in E. coli by increasing NADPH accumulation.

A novel physically cross-linked pH-responsive hydrogel with enhanced mechanical performance (PCAD) was prepared from chitosan (CS), acrylic acid (AA) and (2-dimethylamino) ethyl methacrylate (DMAEMA) via in situ free radical polymerization for controlled drug delivery. The successful fabrication of the hydrogels was verified by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurements. Scanning electron microscopy (SEM) and mechanical analyses demonstrated that the morphological and mechanical behaviors of the resultant hydrogels were strongly affected by the content of AA and DMAEMA. Moreover, the swelling properties of these hydrogels were systematically investigated, and the results indicated that they exhibited strong pH sensitivity. The drug delivery applications of such fabricated hydrogels were further evaluated, from which Bovine serum albumin (BSA) and 5-fluorouracil (5-Fu) were chosen as the model drugs for in vitro release. The results showed that the amount of 5-Fu and BSA released can be tuned by changing the composition of the hydrogel and the pH of the medium. Toxicity assays confirmed that the blank hydrogels had negligible toxicity to normal cells, whereas the 5-Fu-loaded hydrogels remained high in cytotoxicity for LO2 and HepG-2 cancer cells. As seen from the results, PCAD hydrogels seem to have a potential application in drug-delivery systems controlled by the external pH value for cancer therapy.

Research on corrosion of archaeological porcelain glaze has rarely been carried out in the past, although corrosion damage precious heritage items continuously. A group of black-glazed porcelains from the Song Dynasty was excavated at a poor conservation site in Chongqing, and one of their fragments was investigated with optical microscope, SEM-EDX, FTIR and Raman spectroscopy. The results showed that the alteration crust of the glaze mainly consisted of silica-rich gel and contained a variety of heterogeneous phases, including the liquid phase separation structure and different crystals. The crystals mainly include hematite, magnetite, rutile, pseudobrookite and silicon dioxide. The inter-diffusion reaction between alkalis in glaze and hydrogenated species in contact solution was the main reaction, which led to the formation of silicon-rich hydrate layers. The amorphous layers eventually transformed into acicular silica crystals under long exposure to environment.

A pH-, temperature- and salinity responsive hydrogel with enhanced mechanical performance was developed based on semi interpenetrating network that was formed as a result of concurrent free radical polymerization of acrylic acid (AA), oligo(ethylene glycol) methacrylate (OEGMA) and 2-(2-methoxyethoxy) ethyl methacrylate (MEO2MA) along with chitosan (CS) for controlled drug delivery. The mechanical behaviors and swelling properties of these hydrogels were systematically investigated, and the results indicated that they were strongly affected by the content of AA and MEO2MA and exhibited strong pH-, temperature and salinity sensitivity. Bovine serum albumin (BSA) and 5-Fluorouracil (5-Fu) were used as the model drugs to evaluate the sustained release of the hydrogel. The result indicated that the amount of both drugs released was relatively low in acidic condition (pH 1.2) but high in neutral environment (pH 7.4), and the release rate of the drugs was slower at 37 °C than that at 25 °C. Cytotoxicity results suggested that the blank hydrogels had negligible toxicity to normal cells, whereas the 5-Fu-loaded hydrogels remained high in cytotoxicity for LO2 and HepG2 cancer cells. These results suggest that the synthesized hydrogels have the potential to be used as an effective pH/temperature sustainable site-specific oral drug delivery in intestine and colon.

BACKGROUND Although methyl acrylate has been graft polymerized from cellulose and functionalized with hydrazine and hydroxylamine for removal of copper and nickel ions, the adsorption capacity was less than 80 mg g−1. The present work reported hydrazinolysis of cellulose-graft-polymethyl acrylate and remarkably improved adsorption capacity for Cu(II) and Ni(II) in aqueous solution. RESULTS Hydrazinolyzed cellulose-graft-polymethyl acrylate (Cell-g-PMA-HZ) has been prepared by ceric salt-initiated graft polymerization of methyl acrylate from microcrystalline cellulose surface and subsequent hydrazinolysis with hydrazine hydrate. The successful synthesis was confirmed by Fourier-transform infrared spectroscopy, 13C-NMR, elemental analysis, scanning electron microscopy and thermogravimetric analysis. Adsorption behavior of Cell-g-PMA-HZ for Cu(II) and Ni(II) were studied through batch static adsorption processes and column chromatography methods. The influences of graft yield, initial pH, contact time and temperature on adsorption capacity of Cell-g-PMA-HZ as well as adsorption equilibrium, kinetic and thermodynamic properties were studied in detail. Kinetic adsorption can be explained by pseudo-second-order and adsorption isotherms fitted with Langmuir isotherm model, from which maximum equilibrium adsorption capacity can be derived as 229.36 mg g−1 for Cu(II) and 173.91mg g−1 for Ni(II) at 28°C. Further thermodynamic investigation indicated that adsorption of Cu(II) and Ni(II) by adsorbent Cell-g-PMA-HZ was exothermic and spontaneous under the studied conditions. CONCLUSIONS Hydrazinolysis of cellulose-graft-polymethyl acrylate has been accomplished. As an adsorbent, the prepared Cell-g-PMA-HZ was reusable and fairly efficient for removal of Cu(II) and Ni(II) from aqueous solution. © 2015 Society of Chemical Industry

Cobalt blue is a famous pigment in human history. In the past decade it is widely reported that the cobalt aluminate has been detected in ancient ceramics as blue colorant in glaze, yet the acquired Raman spectra are incredibly different from that of synthesised references, necessitating a reassessment of such contradictory scenario with more accurate analytic strategies. In this study, micro-Raman spectroscopy (MRS) and scanning electron microscopy (SEM) in association with energy dispersive spectrometry (EDS) were performed on under-glaze cobalt pigments from one submerged blue and white porcelain shard dated from Wanli reign (1573–1620 CE) of Ming dynasty (1365–1644 CE) excavated at Nan'ao I shipwreck off the southern coast of China. The micro-structural inspection reveals that the pigment particles have characteristics of small account, tiny size, heterogeneously distribution, and more importantly, been completely enwrapped by well-developed anorthite crystals in the glaze, indicating that the signals recorded in previous publications are probably not from cobalt pigments themselves but from outside thickset anorthite shell. The further spectromicroscopic analyses confirm this presumption when the accurate spectra of cobalt aluminate pigment and surrounding anorthite were obtained separately with precise optical positioning. Accordingly, we reassess and clarify the previous Raman studies dedicated to cobalt blue pigment in ancient ceramics, e.g. cobalt blue in celadon glaze, and in turn demonstrate the superiority and necessity of coupling spectroscopic analysis with corresponding structure observation, especially in the characterization of pigments from complicated physico-chemical environment like antiquities. Thus, this study promotes a better understanding of Raman spectroscopy study of cobalt blue pigments in art and archaeology field.

Laser ablation coupled to multicollector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) allows accurate and precise isotope ratio determination of solid samples in a quasi-nondestructive manner, making the technique interesting for isotopic provenance studies of valuable historical artifacts. In order to enable LA-MC-ICPMS analysis of objects that cannot be transported to the laboratory for analysis, a portable laser ablation sampling device was applied. Ablated material was collected on filters, which were subsequently analyzed in the laboratory by means of MC-ICPMS. Filters were analyzed by: (I) acid digestion followed by solution nebulization MC-ICPMS and (II) fast scanning filter ablation coupled to MC-ICPMS. For both procedures, the analytical performance was investigated for lead isotope ratio measurements in ceramics, lead ore (galena) and the metallic lead standard NIST SRM 981. Filter digestion followed by solution analysis allowed determination of lead isotope ratios with external precisions of better than 0.10‰. Mass-dependent deviations towards lighter isotope ratios of 0.10‰ per u were observed for metallic lead, which indicates to a low extent isotopic fractionation during the sampling procedure. Filter ablation coupled to MC-ICPMS resulted in reduced precision compared to the solution measurements. However, it enabled straightforward simultaneous isotopic and elemental analysis by splitting the carrier gas flow to a MC-ICPMS and quadrupole ICPMS. In summary, portable LA sampling followed by MC-ICPMS analysis was shown to enable lead isotope ratio determinations of objects in the field with an analytical performance similar to a laboratory-based analysis. The approach was applied to lead isotope provenancing of ancient Chinese ceramics.