Search results

The purpose of this paper is to identify different automotive coatings using Confocal Raman microscope which could hardly be differentiated with Fourier transform infrared microscope (FTIR).

Raman spectroscopy was used to provide extra vibration information to infrared spectroscopy. Paints preparation was not necessary, and only 30 s was needed for each sample in an optimised method. Paints were first analysed by FTIR and then compared with Raman microscope.

Raman microscope was used to address the lack of ability of FTIR in discriminating four groups of paints in same colours. This study indicated that Raman microscopy is especially effective in sensing pigments and could successfully identify all pigments in the paints.

The two instruments in combination produce accurate results than when used individually, especially in complex and multi-layered paints analysis.

The method proved to be fast, accurate and non-destructive, and it could be easily applied to real cases.

With this method, scientists could discriminate some coating types which were hard to be discriminated by other techniques.

Ballpoint pen ink analysis is important for forensic scientist which can collect valuable information on questioned document. Inks widely used now constitute many substances to improve needed ink characteristics, including the coloring material (dyes or pigments), inks, solvents and resins. The complex components of the inks confront forensic ink chemists with a big challenge to carry out this analysis. However, because of the great importance of determining whether two pieces of written text originated from the same ink, therefore, comparison of different writing inks on a document to forensic scientist, many techniques have been tentatively employed in the ink analysis. In this study, Raman microscope was employed successfully in the analysis of inks. The paper aims to discuss these issues.

Damped or wet samples cannot be analyzed by IR if dehydration is not carried out FTIR observation, because of the extremely strong absorbance of water. Raman spectroscopy can cover the shortage of FTIR spectroscopy because water has weak absorbance in Raman spectroscopy. Raman shifts can give extra peak information because it usually has different positions with FTIR spectroscopy. A Renishaw inVia confocal Raman microscope system with two lasers emitting at 532/633 nm, charge-coupled device detector was employed collecting the Raman spectrum. Laser was chosen for emission in 1-100 percent power depending on the proper energy to get signal strong enough and protect the samples from burning. At least triple-tests were performed for each sample.

The result indicated that Raman spectroscopy could easily remove the interference caused by the paper which could hardly be removed with infrared spectroscopy. No sample preparation was required and only 30 s was needed for each sample in the optimized method. The method proved to be fast, accurate, non-destructive and could be easily applied to the real cases. The primary survey on inks from different market indicated five kinds of inks could be identified. The indicative peaks of each kind of ink (693, 1,150-1,210, 1,280-1,300, 1,360-1,400 and 1,531 cm−1) were summarized. The distributions of the inks in markets were also illustrated. Ink using alkyd resin as connecting materials or copper phthalocyanine as pigment decreased significantly. The data in this study would be helpful for the forensic scientists to identify these inks and examine the questioned document.

No previous studies on the analysis of inks in China market were found to the authors’ best, so the forensic scientists have no idea about the method using Raman for discrimination which proved to be effective, accurate and fast, the indicative peaks of each inks, the distributions in the markets, and therefore, the possibility to encounter specific ink in cases The data in this study would be helpful for the forensic scientists to identify these inks and examine the questioned document.

The purpose of this paper is to introduce an effective method to discriminate seal inks with Raman microscopy.

Raman spectra could effectively avoid interference from the paper and give extra peak information in the inks discrimination and identification. Thus, a Renishaw invia confocal Raman microscope system was employed for ink analysis in this study. A total of 12 representative seal ink samples, widely used in seven Chinese provinces, were investigated using the latest model of Renishaw Raman microscope.

Four types of inks were identified and discriminated successfully. Popular pigments such as Pigment Scarlet Powder, Pigment Yellow 55, phthalocyanine blue, Bronze red C and PbCrO3 were all identified in these seal ink samples. The indicative peaks to identify and discriminate the inks were also summarised and tentatively interpreted.

More ink samples were needed to establish a useful library. Many other pigments used in inks were still unknown.

This method was proved to be fast, accurate and non-destructive, and it could be more easily applied in real cases than Fourier transform infrared spectroscopy.

This method can help scientists discriminate some inks, which can hardly be discriminated by other techniques. The results are useful for the ink analysis and discrimination in forensic (document examination and file source identification), polymer and pigment fields.

This study aims to using Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and scanning electron microscope/energy dispersive Xray spectrometer to identify different automotive coatings for forensic purpose.

Two four-layered samples in a hit-and-run case were compared layer by layer with three different methods. FTIR spectroscopy was used to primarily identify the organic and inorganic compositions. Raman spectrum and scanning electron microscope/energy dispersive Xray spectrometer (SEM-EDS) were further used to complement the FTIR results.

Two weak and tiny peaks in one layer found between two samples by FTIR, Raman microscope and SEM-EDS verified the result of differences. The study used the three instruments in combination and found it’s effective in sensing coatings, especially in the inorganic additives.

Using these three instruments in combination is more accurate than individually in multilayered coating analysis for forensic purpose.

The three different instruments all present unique information on the composition, and provided similar and mutually verifiable results on the two samples.

With this method, scientists could identify and discriminate important coating evidences with tiny but characteristic differences.

This paper aims to provide a technical insight into recent molecular sensor developments involving nanophotonic materials and phenomena.

Following an introduction, this highlights a selection of recent research activities involving molecular sensors based on nanophotonic technologies. It discusses chemical sensors, gas sensors and finally the role of nanophotonics in Raman spectroscopy. Brief concluding comments are drawn.

This shows that nanophotonic technologies are being applied to a diversity of molecular sensors and have the potential to yield devices with enhanced features such as higher sensitivity and reduced size. As several of these sensors can be fabricated with CMOS technology, potential exists for mass-production and significantly reduced costs.

This article illustrates how emerging nanophotonic technologies are set to enhance the capabilities of a diverse range of molecular sensors.

The purpose of this study is to explore the feasibility of utilizing agricultural (almond shell, rice husk and wood) waste biochars for partial cement replacement by evaluating the relationships between the physiochemical properties of biochars and the early-age characteristics of cement pastes.

Biochars are prepared through the thermal decomposition of biomass in an inert atmosphere. Using varying percentages, biochars are used to replace ordinary Portland cement (OPC) in cement pastes at a water/binder ratio of 0.35. Characterization methods include XPS, FTIR, SEM, TGA, BET, Raman, loss-on-ignition, setting, compression and water absorption tests.

Accelerated setting in biochar-modified cement pastes is attributed to chemical interactions between surface functional groups of biochars and calcium cations from OPC, leading to the early development of metal carboxylate and alkyne salts, alongside the typical calcium-silicate-hydrate (C-S-H). Also, metal chlorides such as calcium chlorides in biochars contribute to the accelerate setting in pastes. Lower compression strength and higher water absorption result from weakened microstructure due to poor C-S-H development as the high carbon content in biochars reduces water available for optimum C-S-H hydration. Amorphous silica contributes to strength development in pastes through pozzolanic interactions. With its optimal physiochemical properties, rice-husk biochars are best suited for cement replacement.

While biochar parent material properties have an impact on biochar properties, these are not investigated in this study. Additional investigations will be conducted in the future.

Carbon/silicon ratio, oxygen/carbon ratio, alkali and alkaline metal content, chlorine content, carboxylic and alkyne surface functional groups and surface areas of biochars may be used to estimate biochar suitability for cement replacement. Biochars with chlorides and reactive functional groups such as C=C and COOH demonstrate potential for concrete accelerator applications. Such applications will speed up the construction of concrete structures and reduce overall construction time and related costs.

Reductions in OPC production and agricultural waste deterioration will slow down the progression of negative environmental and human health impacts. Also, agricultural, manufacturing and construction employment opportunities will improve the quality of life in agricultural communities.

Empirical findings advance research and practice toward optimum utilization of biomass in cement-based materials.

This study aims to systematically investigate the tribological behaviors of metal and polyethylene using lubricants composed of four synovial fluid (SF) components. In addition, the changes in protein conformation during wear were analyzed to establish the correlation between protein conformation and tribological properties.

A pin-on-disk tester with multidirectional sliding motion was used for tribological properties observation between metal and polyethylene pairs. Simulated SFs with four main constituents were used as the testing lubricants. Differential scanning calorimetry and Raman were used to characterize the changes in protein conformation during wear.

The coupling of lipids and hyaluronic acid further suppressed protein denaturation. The protein structures of the adsorption film and the ensnared protein chains in the friction zone were maintained to a certain extent, thus improving the friction and wear of polyethylene.

These findings established the correlation between protein conformation and friction and wear, promoting the understanding of the lubrication mechanism of artificial joints.

The curved and tribologically highly stressed surfaces of bearing components pose a major challenge for steel alloys or tribological resistant coatings like tetrahedral amorphous carbon (ta-C) coatings which in particular have an increased risk of delamination due to the significantly increased residual stresses. A possibility to prevent coating failure is the use of dopants while maintaining or even increasing tribological properties. This study aims to compare the tribological behavior of several doped diamond-like-carbon coatings with an undoped ta-C coating under varying slip conditions and Hertzian pressure up to 1800 MPa.

For this purpose, the tribological behavior was studied using of a ball-on-disc tribometer and a two-disc test rig under mixed/boundary conditions. The tests were conducted with coated specimens against uncoated 100Cr6 steel. Additionally, the influence of lubrication additives was studied due to the use of two fully formulated PAO-based oils, one without and one with molybdenum containing additives. The friction was measured in situ, and the wear was analyzed trough laser scanning microscopy and tactile measurement.

It was shown that the use of doped ta-C coatings exhibited a tendency for a more favorable tribological behavior compared to undoped ta-C coatings, with no general dependence on the lubricants used. The use of the most suitable coatings reduced the wear of the steel counter-body considerably.

To the best of the authors’ knowledge, this is the first approach of testing the tribological behavior of these doped ta-C coatings, developed for friction efficiency, in dependency on lubrication additives under the given load collective. The approach is relevant to determine whether the friction reduction and the wear inhibition of these coatings are suitable for higher contact pressures and load cycles.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2022-0336/

Identification and characterization of organic pigments and dyes used in works of art and cultural heritage material such as prints, drawings, manuscripts, paintings, and textiles can provide important information for dating, authentication, and conservation treatment of these objects and studying art history in general. Applications of surface‐enhanced Raman scattering (SERS) for this purpose have recently attracted increasing attention of both academic scientists and museum researchers. This paper aims to review the latest development involving the emerging applications of SERS for the analysis of organic pigments and dyes used in works of art and cultural heritage material.

First, the importance of organic pigments and dyes in the studies of works of art and cultural heritage material and the challenges in their identification and characterization are briefly summarized. This is followed by a discussion on sampling considerations in the context of art and archaeology. Then the fundamental principle of SERS, SERS instrumentation and different types of SERS substrates are reviewed. Finally, selected examples of SERS applications to the identification of organic pigments and dyes, including the analysis of a couple of samples of artistic and archaeological interest, are presented and discussed.

The last few years have witnessed the emergence of SERS as a non‐destructive or micro‐destructive technique for the characterization of organic pigments and dyes found in artistic and archaeological objects. Spectroscopic and microscopic measurements using SERS have provided some novel information and answers to a wide variety of questions. However, SERS application to the field of art and archaeology is still in the fledging stage of development and requires closer collaboration between academic scientists and museum researchers. But the range of possible applications is broad. Future trends point to a strong need for the development of portable instruments for field applications.

By compiling this review, the authors hope to direct more attention toward SERS and bring together the expertise in the scientific, museum and art community to further explore the possibilities of SERS in rapid and direct identification of pigments and dyes under field conditions.

Dyeing and printing are important steps in textile manufacturing. After the process completion, these dyes are released in the effluent. These dyes impart an unacceptable appearance but are also toxic to the soil and water bodies. The present research has been carried out to study the rate of photocatalytic degradation of an azo dye, namely, CI Direct Green 26, using titania nanoparticles under ultra violet (UV) irradiation as a function of temperature and time. Azo dyes account for the majority of all dyestuffs are produced and extensively used in the textile, paper, food, leather, cosmetics and pharmaceutical industries. Titania nanoparticles have been found to successfully degrade these dyes in the presence of UV light. The purpose of the present paper was to study the photodegradation of azo dyes using titania nanoparticles at different temperatures and time periods.

Titania nanoparticle concentration of 0.1% (w/v) was dispersed in distilled water by sonication for 1 h in sonication bath. The of rate of degradation of Direct Green 26 dye in the titania nanoparticle dispersion, under UV-A exposure was studied at different temperatures ranging from 25°C to 65 °C for time periods ranging from 1 h to 6 h. Photocatalytic degradation tests were performed in a specially designed UV reactor chamber. Raman spectroscopy of Titania nanoparticles, dye and titania/dye mixture before and after UV exposure was carried out using Confocal Laser Dispersion Raman Microscope (Renishaw, UK) with 785 nm excitation laser.

Titanium dioxide is an efficient photocatalyst for decolourisation of direct dye. The photodegradation of the direct Green dye was found to follow the pseudo first-order reaction. The Arrhenius activation energy was found to be 24.8 kJ/mol with A value of 0.0013 for the photocatalytic degradation of the dye. Raman spectroscopy also confirmed the adsorption of dye on titania nanoparticle and its complete degradation on exposure to UV light.

This research highlights the application of titania nanoparticles for the effective degradation of dye in the effluent from textiles, clothing, paper and any kind of dyeing process. Azo dyes account for the majority of all dyestuffs are produced and extensively used in the textile, paper, food, leather, cosmetics and pharmaceutical industries. Titania nanoparticles have been found to successfully degrade these dyes in the presence of UV light which can be very beneficial for the effluent treatment plants in textile and other industries.

Azo dyes are one of the harmful pollutants released in textile waste water. The degradation and removal of the coloured waste in the textile effluent is an important environmental concern and needs to be investigated. The research is one of the first to investigate and understand the mechanism of the degradation of an azo dye in the presence of titania nanoparticles by Raman spectroscopy.