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1.
A sodium copper formate, first described in 2002, can also form on copper alloys with sodium originating from soda glass hydrolysis. The frequent occurrence (50% of 250 cases of glass-induced metal corrosion) is due to the presence of formaldehyde emissions in storage and its direct reaction to formate in the alkaline surface films. The compound can be produced without the presence of acetate when chalconatronite or metal coupons immersed in soda solution are exposed to formaldehyde vapours. The crystal structure, derived from X-ray powder diffraction, yielded the sum formula Cu4Na4O(HCOO)8(OH)2·4H2O. Except for the absence of acetate in the structure, this is in good agreement with the 2002 publication. To assess which kind of combined glass/metal objects are affected, a number of large museum collections were surveyed. Sodium copper formate was detected as a corrosion product using mainly micro-Raman spectroscopy, for instance, on 18 painted Limoges enamels, eight glass vessels with metal mountings, glass beads on metal wire from 11 bridal crowns, nine Christmas tree balls with wire decoration, 40 pieces of jewellery with glass gems, three daguerreotypes, and one miniature with cover glasses.  相似文献   

2.
《文物保护研究》2013,58(2):104-112
Abstract

An exhibition case displaying ancient bronzes was found to have a high leak-rate and was subject to a variety of environmental factors. Because of the original case design, passive means of control were not proving effective. A simple, low-output (below 28l.min?1) drying system based on hollow fibre (polysulfone) technology was tested and installed in the case to maintain the microenvironment below 43% relative humidity (RH). The membrane was tested below industrially-specified pressure parameters (less than 4 bar) and found to produce a range of consistent RH outputs suited to museum use. After some years in service, the system has proved reliable and simple to operate; optimum performance was achieved with more continuous operation.  相似文献   

3.
《文物保护研究》2013,58(3):169-173
Abstract

A complete summary of equations for leakage of enclosures is given, including vapour diffusion through still air in openings, and infiltration of air/vapour/particulate mixture. Stack pressure due to temperature and relative humidity difference drives most infiltration. Experiments confirmed the diffusion and infiltration equations for small and medium-size enclosures. Leakage for a carefully made display case with ordinary materials has been reduced to the microbarometric limit of about 0·03 of an air change per day. Simplified tables and charts of leakage are given for 0·1, 1·0 and 10m enclosures, as a function of crack width, hole width, and wall permeability.  相似文献   

4.
ABSTRACT

Chalconatronite, Na2[Cu(CO3)]2·3H2O, is formed as a corrosion product when copper alloys are exposed to sodium carbonate solutions in the air. This also happens when metals come into contact with corroding soda glass which forms alkaline surface films in reaction with humidity from clean air. More often, substantial amounts of formaldehyde are present indoors which react to formate via the Cannizzarro reaction and accumulate over time in the films. Twenty cases of chalconatronite (including two mentioned in the literature) are reported as occurring on heritage objects with glass in contact with copper alloys: Baroque reliquaries with set glass gems, enamel on metal (sixteenth century and a modern replica of intentionally unstable composition), Christmas tree glass baubles with wires, glass buttons with metal shanks, a glass figure with a wire support, miners’ lamps, and a glass framed daguerreotype. These confirmed identifications might help conservators in investigating similar cases to shed more light on the formation conditions.  相似文献   

5.
ABSTRACT

Historic buildings in Denmark have a high relative humidity (RH) all year, so the interiors are exposed to biological degradation. The acceptable range for RH is 60–70%, which is higher than the usual recommendations for museums and galleries. There are two options for humidity control: conservation heating or mechanical dehumidification. Calculation of the energy performance of a generic building was used to determine which method is the most efficient. Studies of a cottage in Liselund Park, and of two medieval churches in Hellerup and Vemb have confirmed these predictions: dehumidification is less energy consuming than conservation heating in buildings with poor thermal insulation and a moderate air infiltration rate (AER?<?0.6?h?1). Dehumidification is suitable for historic buildings, where heating is not needed for human comfort. A condensing dehumidifier uses less than half the energy per kg water compared to an absorption dehumidifier. But it does not work at temperatures below 2°C. The combination of a condensing dehumidifier and a little heating to prevent frost is the most energy efficient solution for humidity control. These results are only valid in mild and humid climatic conditions similar to Denmark.  相似文献   

6.
《文物保护研究》2013,58(3):201-210
Abstract

Thirty artists' colors have been exposed for 12weeks to 120ppb of formaldehyde in purified air as well as to purified air alone (control experiment). The exposure was carried out in the dark at ambient temperature (19 ± 2°C) and humidity (RH 44–52%). Color change (?E) was measured using a reflectance color analyzer after one, two, three, four, six, eight, 11 and 12 weeks of exposure. Color parameters (x, y, X, Y, Z, L*, a*, b* and ?E)"were also calculated from the 380–700nm spectra, recorded with a reflectance spectrophotometer, of unexposed colorants and of colorants exposed for 12 weeks to purified air and to formaldehyde. Regression analysis of the two data sets indicated that the color changes measured by these two methods were in excellent agreement (nearunity slopes, with correlation coefficients > 0.99). Exposure to either formaldehyde or pure air on watercolor paper resulted in little or no color change for all the colorants tested, including inorganic colorants, alizarin lakes, quinacridones, triphenyl methanes, indigo derivatives, arylamides and natural colorants such as curcumin. Formaldehyde, which is ubiquitous in indoor air, including museum air, does not appear to be a major threat to colorants in museum collections.  相似文献   

7.
ABSTRACT

Sandstone is a common sedimentary rock that is easily carved due to its weakly cemented fine grains and relatively low strength. Therefore, numerous large-scale grottoes in China are made of sandstone. However, these sandstone cultural heritage structures are often seriously damaged due to temperature and humidity changes, air pollution, biodeterioration, and repeated dissolution and crystallization of soluble salts. In general, it is imperative that a consolidant capable of providing cohesion by infilling pores between the stone grains is synthesized. In recent years, it has been reported that using organic consolidation materials for sandstone protection comes with various negative effects, such as a short lifetime, poor compatibility, and preservation damage. Using inorganic consolidation materials to protect sandstone seems to be one of the research trends for the future. Herein, this paper introduces a permeable, inorganic magnesium-based material (MMH solution) for silica sand consolidation. To assess this consolidant, the paper investigates the influence of varying molar ratios of MgO:MgCl2·6H2O:H2O on properties such as penetration depth, consolidation weight, colour variation, and compressive strength. The results demonstrate that the molar ratios of MgO:MgCl2·6H2O:H2O can significantly affect the consolidation performance. Additionally, it is believed that the MMH solution of MgO:MgCl2·6H2O:H2O?=?5:1:16 can be successfully used for the consolidation of silica sand, as the cubic specimens’ surface micrographs show good compatibility between the consolidation product and sand grains. Experiments (i.e. weight loss rate and mineralogical compositions analysis) are performed to evaluate the cubic specimens’ water resistance properties after being immersed in water. Furthermore, the consolidation material’s failure mechanism as a self-sacrificing material is preliminarily analyzed. Results indicate that MMH solution is a promising conservation material that shows great potential for consolidating severely weathered sandstone.  相似文献   

8.
Abstract

The objective of the study presented here was to determine the socio-cultural factors that enhanced the use and transfer of scientific information among agricultural scientists in south eastern Nigeria. The implications of some of these factors for agricultural development are highlighted.

Structured questionnaires were distributed to a stratified random sample of 300 scientists. Two hundred and ten (210) questionnaires were mailed while 90 were self-administered. Two hundred and forty-five (81·6%) usable responses were received and analysed. Data were also generated from interviews with selected members of the stratified random sample. Analyses focused on social and cultural factors of (1) motivation, (2) computer appreciation, (3) choice of media for research communication, (4) recipients of research communications, and (5) scientists' activities considered for assessment and reward. Frequency counts were the presentation techniques used to elucidate results.

Results showed that scientists were motivated more in the use and transfer of scientific information by social factors of self-development (53·3%) and job security (12·9%) than by social factors of scientific problem solution (19·6%) and intellectual contribution (12·6%).

Cultural factors of development in information technology (36·8%), adequate and relevant information resources (12·6%) and previous information attitudes (24·5%) also influenced scientists. Although five types of recipient groups of research communications were identified, the study noted that there was a disproportionately inadequate diffusion of research communications to two important groups of “national planners” and “external aid bodies”, who plan and finance agricultural development. Only 5% of scientists sent research communications to national planners and only 3·7% of scientists sent research communications to external aid bodies.

Strategies for assessing other quantifiable elements of productivity by scientists outside journal publications and for diffusing adequate scientific information to national planners and external aid bodies are deemed necessary.  相似文献   

9.
《文物保护研究》2013,58(4):229-240
Abstract

This paper describes a novel technique to stabilize the relative humidity (RH) of the air inside museum showcases by using a synthetic hydrophobic membrane coupled with a hygroscopic solution in a membrane contactor. RH-monitoring data for two identical test cases, one of them controlled by a set-up with a plane-plate membrane contactor crossed by forced air and lithium chloride (LiCl) solution flows, show a significant stabilizing effect on RH fluctuations. A theoretical model permits forecasts in close agreement with the experimental RH data. Further calculations carried out over a one-year period show that notable damping of external RH variations can be obtained by using a low air circulation rate, small membrane surface area and low solution mass per unit case volume. A more general analytical solution in harmonic conditions is derived and discussed.  相似文献   

10.
《文物保护研究》2013,58(2):100-106
Abstract

The paper discusses the methodology adopted for and the results derived from a pilot project to conserve the lead and lead alloy communion tokens in the collections of St Andrews University. For the project a new conservation process, ‘potentiostatic reduction’, was developed, involving reduction of the tokens at ?1·2V vs. SCE (saturated calomel electrode) in 0·5M H2SO4, The aim of the pilot project was to test the effectiveness of the new process in tackling a largescale conservation problem by observing its effects on a wide range of tokens made of various alloys and suffering from varying degrees of corrosion. The results of the pilot project indicated that potentiostatic reduction is as effective as standard electrolytic reduction. Since the new technique greatly reduces the time required for the conservation of individual artifacts, there are substantial savings in conservation costs.  相似文献   

11.
《文物保护研究》2013,58(4):170-175
Abstract

The construction of a 1·80 × 3·00 m vacuum table is described. Instead of fabricreinforced neoprene rubber type blankets, electric radiant heat panels are used to reach a maximum of 95°C. Heating takes approximately one hour.  相似文献   

12.
ABSTRACT

Adsorbent materials can be used for the removal of organic acids from air in storage rooms with heritage collections. The organic acid removal efficiency of two commercially available activated carbon air-filters were tested in situ in two unoccupied stores with densely packed collections. One filter was designed for outdoor type pollutants (Filter A), while the other was designed for organic acids in indoor air (Filter B). Furthermore, the acetic acid removal efficiency of a desiccant silica gel rotor used for dehumidification was measured in a laboratory at different relative humidity levels. Finally, passive removal of acetic acid by silica gel and unfired clay brick were tested in a chamber, and for clay brick at room level as well. Filter B had the highest removal efficiency. The removal efficiency of both filter types depended on the airflow and the filter performance varied considerably in situ from the values reported from standard laboratory tests. Increasing the filter airflow reduced the removal efficiency from 77% and down to 7% for Filter A, and from 92% to 24% for Filter B. There was almost no effect of active air filtration on the concentration of organic acids when this was measured in the middle and in the corner of the storage rooms away from the ventilation inlets. The desiccant dehumidifier removed 98–100% of the acetic acid from the air, independently of the relative humidity. The desiccant rotor will, however, only be running when there is a need for dehumidification and as a result will only periodically remove pollutants. The high acid removal efficiency by dry silica gel was furthermore demonstrated in a chamber test. A clay brick wall in a test room established a concentration gradient across the room and reduced the concentration of organic acids by 56% compared to close to the emission source.  相似文献   

13.
Case files are voluminous and present challenges to archivists, government departments, and other institutions that are charged with the responsibility of managing these records either throughout or at various stages of their life cycle. To date, archivists and records administrators, both in Canada and worldwide, have recognized the case file challenge and are rethinking solutions for dealing with this persistent problem. This article argues that by building on our cumulative knowledge acquired through years of applying macroappraisal and functional analysis to the appraisal of government records, and staking out a modern definition of “case file records” based on their transactional characteristics, we indeed do have the skills and the expertise to tackle the problem and develop a new solution for case file records. Rather than taking a piecemeal approach or relying on sampling techniques, Library and Archives Canada (LAC) Case Files Appraisal Working Group (CFAWG)1 demonstrates how to consistently make keep-destroy appraisal decisions for the disposition of operational case file records.2  相似文献   

14.
Lead white is widely used as a white pigment in the history of Persian painting. This paper focuses on three Persian treatises dated between the twelfth and the sixteenth century, which explained different manufacturing methods of lead white or sefidāb-i-sorb. Experimental reconstruction of each recipe to access the comprehensive meaning of the text and analytical studies with X-ray powder diffraction on products of recipes revealed white compounds other than the previously known products of hydrocerussite (Pb(OH)2?·?PbCO3) and cerussite (PbCO3) in samples. Chlorine-containing raw materials mentioned in these recipes lead to the chemical products of laurionite (Pb(OH)Cl), blixite (Pb8O5(OH)2Cl4), and phosgenite (Pb2Cl2(CO)3) in the final products. These data lead to the hypothesis of the discrepancy of the lead white pigment between Iran and Europe and a marked probability of other compounds in historic Persian lead white samples.  相似文献   

15.
* The Government White Paper and the eight working papers which have followed it, despite the lack of detail, constitute the most radical in the recent series of NHS reorganizations, 1974–88. Each of the papers covers a major issue. A good summary of all eight was published in The Health Service Journal, 1989, 2 March, 254–7.
is likely to have a number of implications for library services in the National Health Service once the proposals are implemented. Here three librarians—Michael Carmel ? ? Michael Carmel's paper first appeared in the BPMF Medical Library Bulletin for May 1989.
, Roy Tabor ? ? The papers by Roy Tabor and Anne Willis are based on papers presented at a meeting of LAMHWLG at LAHQ, London, 8 June 1989.
, and Anne Willis ? ? The papers by Roy Tabor and Anne Willis are based on papers presented at a meeting of LAMHWLG at LAHQ, London, 8 June 1989.
—describe the ways in which they feel libraries and librarians may be affected by the changes and highlight the issues which will be of increasing importance for both, such as medical audit, performance indicators and quality measures. The common themes which emerge are an acknowledgement that the changes herald risks as well as opportunities, and that it is essential for librarians to adopt a positive and constructive approach to them and ensure that they are fully involved with developments.
  相似文献   

16.
The h index is a widely used indicator to quantify an individual's scientific research output. But it has been criticized for its insufficient accuracy—the ability to discriminate reliably between meaningful amounts of research output. As a single measure it cannot capture the complete information on the citation distribution over a scientist's publication list. An extensive data set with bibliometric data on scientists working in the field of molecular biology is taken as an example to introduce two approaches providing additional information to the h index: (1) h2 lower, h2 center, and h2 upper are proposed, which allow quantification of three areas within a scientist's citation distribution: the low impact area (h2 lower), the area captured by the h index (h2 center), and the area of publications with the highest visibility (h2 upper). (2) Given the existence of different areas in the citation distribution, the segmented regression model (sRM) is proposed as a method to statistically estimate the number of papers in a scientist's publication list with the highest visibility. However, such sRM values should be compared across individuals with great care.  相似文献   

17.
《文物保护研究》2013,58(3):148-152
Abstract

Mineralogical changes which occur during the reaction of copper(II) chloride with carbonate in aqueous solution have been investigated, and compared with those involving copper(I) chloride, nantokite, CuCI, and copper artifacts coated with malachite, CU2CO3(OH)2 The reactions observed and the products obtained are seen to have implications with respect to the use of aqueous sodium carbonate solutions to stabilize archaeological copper objects. The frequent observation of the mineralogically rare species chalconatronite, Na2Cu(CO3)2·3H2O, on the surface of treated objects is readily explained by known reaction chemistry. Its formation can be minimized by washing the object after treatment.  相似文献   

18.
《文物保护研究》2013,58(3):165-184
Abstract

This study investigates the effects of a selection of alkaline reagents, including solutions, pastes and soap gels, used to remove an artificially aged mastic film applied over a primed canvas. Surface changes were examined using visible light and scanning electron microscopy (SEM). Ammonia, whether in solution or gelled with hydroxypropylmethylcellulose (HPMC), required a pH of 10 or higher to remove varnish at an appreciable rate, whereas ammonia in wax paste worked at pH 9. Soap gels based on deoxycholic acid (DCA) were effective at pH 9·5. The rate of removal increases significantly with the addition of benzyl alcohol, while anthracene-9-carboxylic acid (A9C) and 9-fluorenone-4-carboxylic acid (9FOC) soap gels of pH 7·9 worked quickly without the addition of alcohol. Where reagents with a pH of more than 9 were used, some erosion of the priming was observed under SEM. Examination of the topography of residual varnish after treatment and Fourier transform infrared spectroscopy (FTIR) measurements provided evidence in support of models for the mode of action of reagents and soap gels on aged varnish. Ammonia, whether in solution, gel or paste, removes varnish by fracturing on a multi-molecular scale; soap gels not -specifically tailored to remove the varnish act similarly. A9C and 9FOC gels remove the varnish by thinning from the upper surface without fracturing.  相似文献   

19.
《文物保护研究》2013,58(2):137-138
Abstract

Ancient bronzes in the collection of the J. Paul Getty Museum are maintained in low-humidity environments to eliminate the possibility of recurring chloride corrosion. A small, low-power, solid-state air drier was considered as an option to silica gel. This relatively new technology combines electrolytic dissociation of water molecules to hydrogen and oxygen with membrane separation. Hydrogen atoms formed on the anodic side penetrate the membrane and combine with oxygen on the cathodic side to form water. Oxygen atoms that remain on the anodic side recombine to form oxygen molecules. The process of water removal was found to be very efficient, but it is suggested that a portion of the oxygen atoms might react further to form ozone, a reactive molecule generally regarded as a deleterious pollutant in museum atmospheres. This was confirmed by passive sampling for ozone using diffusion tubes. While control levels after 60 days ranged from 0.43 to 1.25 parts per billion (ppb), samplers in the test environment recorded a level of 10.5 ppb, an increase of approximately 10 to 25 times. Developments in solid-state driers may overcome this problem in the future.  相似文献   

20.
This paper proposes to use random walk (RW) to discover the properties of the deep web data sources that are hidden behind searchable interfaces. The properties, such as the average degree and population size of both documents and terms, are of interests to general public, and find their applications in business intelligence, data integration and deep web crawling. We show that simple RW can outperform the uniform random (UR) samples disregarding the high cost of UR sampling. We prove that in the idealized case when the degrees follow Zipf’s law, the sample size of UR sampling needs to grow in the order of O(N/ln 2 N) with the corpus size N, while the sample size of RW sampling grows logarithmically. Reuters corpus is used to demonstrate that the term degrees resemble power law distribution, thus RW is better than UR sampling. On the other hand, document degrees have lognormal distribution and exhibit a smaller variance, therefore UR sampling is slightly better.  相似文献   

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