Amber Samples Research Articles

Extraction and Evaluation of the Effectiveness of Chitosan as Insecticides on the Immature Stages of the Saw-Toothed Grain Beetle Oryzaephilus Surinamensis L. (Coleoptera: Silvanidae)

This study aimed to collect samples of amber rice infected with the saw-toothed grain beetle from local markets in Kirkuk city during 13 December 2023 to 25 April 2024, and the experiments were conducted in the laboratories of the College of Education for Pure Sciences at Kirkuk University from February to April 2024. The toxic effects of chitosan were studied at three different concentrations: 0.5, 1.0, and 1.5 ppm on the immature stages of the saw-toothed grain beetle. The substance exhibited significant effects on the immature stages of the insect , recording the shortest egg incubation period with an average of 8.17 days, while chitosan treatment showed a significantly longer periods of 9.66, 11.69, and 14.00 days for concentrations of 0.5, 1.0, and 1.5 ppm respectively. The larval stage duration had a direct proportionality with the chitosan concentrations, where the 1.5 ppm concentration registered the longest larval period of 22.00 days, as opposed to the control which recorded the shortest period of 13.56 days, and the 0.5 and 1.0 ppm concentrations recorded durations of 17.19 and 19.66 days respectively. In the pupal stage, significant differences were found when the chitosan concentration was increased, with the control treatment having the shortest pupal stage duration of 4.33 days; a direct correlation was found between the concentrations and the pupal stage duration, which decreased to 6.00, 7.59, and 9.07 days for the 0.5, 1.0, and 1.5 ppm concentrations, respectively.

Analysis of Mexican Amber and Natural Resins Using Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy

Amber is a semi-precious gemstone, it is a natural resin formed as a fossil and consists of labdanoid diterpenes. This study involves a compositional analysis of Mexican amber using FTIR Spectroscopy and Raman Spectroscopy, comparing it with resins mixed with sulphur, copal, and rosin, to determine the main spectral features of Mexican amber and identify differences from other fake amber resins. Samples of yellow, red, and green amber were utilised. The equipment used included an ATR FTIR spectrometer and a Raman spectrometer with a 785 nm laser source. In the FTIR analysis, the results reveal that the colour variations in Mexican amber do not reflect structural differences. The ester group is identified in amber through the C=O carbonyl bond at 1727 cm-1, confirmed by a band at 1243 cm-1 and a set of bands between 1200-1060 cm-1 corresponding to C-O-H and O-C-C bonds, respectively. The range between 1000-600 cm-1 is identified as the most crucial for distinguishing authentic amber and determining whether the resin is young or fossilised. In Raman, the main peaks to identify amber are at 1646 cm-1 and 1450 cm-1 with which the ratio of intensities was quantified to determine the maturity of the fossil resin.

Development of a method based on ATR-FTIR spectroscopy to detect maple syrup adulterated with added syrups.

Food adulteration is a global concern, whether it takes place intentionally or incidentally. In Canada, maple syrup is susceptible to being adulterated with cheaper syrups such as corn, beet, cane syrups, and many more due to its high price and economic importance. In this study, the use of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was investigated to detect maple syrups adulterated with 15 different sugar syrups at different concentration levels. The spectra were collected in the range of 4000-650 cm-1 in the absorbance unit. These spectra were used to build six libraries and three models. A method that is capable of performing a qualitative library search using a similarity search, which is based on the first derivative correlation search algorithm, was developed. This method was further evaluated and proved to be able to capture adulterated and reject non-adulterated maple syrups, belonging to the color grades golden and amber maple syrups, with an accuracy of 93.9% and 92.3%, respectively. However, for the maple syrup belonging to the dark color grade, this method demonstrated low specificity of 33.3%, and for this reason it was only able to adequately detect adulterated samples from the non-adulterated ones with an accuracy of 81.4%. This simple and rapid method has strong potential for implementation in different stages of the maple syrup supply chain for early adulteration detection, particularly for golden and amber samples. Further evaluation and improvements are required for the dark color grade. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Electron withdrawing group-dependent substrate inhibition of an α-ketoamide reductase from Saccharomyces cerevisiae

Aldo-keto reductases remain enzymes of interest in biocatalysis due to their ability to reduce carbonyls to alcohols stereospecifically. Based on genomic sequence, we identified aldo-keto reductases of a S. cerevisiae strain extracted from an ancient amber sample. One of the putative enzymes, AKR 163, displays 99% identity with α-amide ketoreductases from the S288C and YJM248 S. cerevisiae strains, which have been investigated for biocatalytic applications. To further investigate AKR 163, we successfully cloned, expressed in E.coli as a glutathione-S-transferase fusion protein, and affinity purified AKR 163. Kinetic studies revealed that AKR 163 experiences strong substrate inhibition by substrates containing halogen atoms or other electron withdrawing groups adjacent to the reactive carbonyl, with Ki values ranging from 0.29 to 0.6 mM and KM values ranging from 0.38 to 0.9 mM at pH 8.0. Substrates without electron withdrawing groups do not display substrate inhibition kinetics and possess much larger KM values between 83 and 260 mM under the same conditions. The kcat values ranged from 0.5 to 2.5s−1 for substrates exhibiting substrate inhibition and 0.22 to 0.52s−1 for substrates that do not engage in substrate inhibition. Overall, the results are consistent with rate-limiting dissociation of the NADP+ cofactor after hydride transfer when electron withdrawing groups are present and activating the reduction step. This process leads to a buildup of enzyme-NADP+ complex that is susceptible to binding and inhibition by a second substrate molecule.

Differentiation between copal and amber by their structure and thermal behaviour

The relationships between the polymerization related to structure and the composition of different types of natural resins were determined. Analyses were carried out by Fourier transform infrared spectroscopy (FTIR), differential thermal analysis–thermogravimetry (DTA-TG) and hot stage microscopy (HSM). Copal specimens were collected from the Mai-Ndombe Lake, Democratic Republic of Congo, and amber pieces that came from Bitterfeld, Germany, and from Kaliningrad, Russia. FTIR spectra of copal show a vibrational band at 1643 cm−1 (C=O stretching) attributed to communic acids, while amber shows a band at 1735 cm−1 associated with ester-group vibrations and a shoulder at about 3340 cm−1, suggesting partial oxidization. DTA shows the main exothermic peak, related to the combustion, at 546–552 °C in amber and at 518 °C in copal. The derivative thermogravimetry (DTG) peaks vary in the different resin types; in amber, they occur at 333–335, 401–404 and 548–555 °C and are related to mass losses of 31, 26 and 39 mass%, respectively; copal peaks are at 394 and 507 °C, with mass losses of 71 and 27 mass%, respectively. In copal, hot stage microscopy (HSM) shows the start of sintering at 131 °C, followed by an expansion produced by the material decomposition and the generation of gases that cannot be released because of the material plastic behaviour. Finally, the increase in pressure produces an explosion that results in a lower viscosity of the liquid, which at this point can no longer support the internal pressure of gases. In amber samples, a smaller decrease in viscosity is observed and the start of sintering occurs at 150 °C with no significant change in their morphology.

Algorithm for the formation of price lists for raw amber taking into account individual consumer characteristics

Purpose. Development of an algorithm for the formation of price-lists for raw amber, taking into account its individual consumer characteristics, which is based on the principle of inheritance of properties. Methodology. In the course of the study, general scientific and special research methods were used: analytical, dialectical, comparative-evaluative, gemmological-economic, comparative-legal, systemic-structural. The main part of the work is based on the practical results of previous studies and expert assessments. Findings. A critical analysis of modern gemmological terminology, which is used in the geological, mineralogical and expert-evaluative study on the individual characteristics of raw amber samples, is carried out, and its content has a direct impact on its further pricing. The specifics of the relationship between the raw, appraisal and consumer amber markets, the subjective features of the gemmological interests of the manufacturer (seller), expert (appraiser) and consumer (buyer) are disclosed. The authors’ method of establishing the relationship of individual consumer characteristics between raw materials and products is proposed, which is based on the principle of inheritance of decorative, geometric and weight characteristics of raw amber. The concept of “individual consumer characteristics of amber” is formulated. Originality. An algorithm for the formation of price-lists for raw amber has been developed, taking into account the individual consumer characteristics of samples, which is based on the principle of inheritance of amber properties formulated by the authors, according to which its natural decorative characteristics are related to direct criteria for evaluating amber, whereas the transformable geometric and weight characteristics of samples are indirect. Practical value. The practical significance of the results obtained lies in the fact that they can be used in research and educational activities by scientists and applicants of higher education, business and financial-and-economic activities of subjects of gemmological relations, law-making and law enforcement activities of public authorities in the process of improving national legislation.

Paulje, mound XI (mound K): new absolute dates and provenience of the earliest amber finds in Serbia

This paper presents three new absolute dates for the central grave of mound XI (K) at the Paulje necropolis in the lower Drina valley. Also, we present the results of FTIR spectroscopy for the amber finds from the 4 mounds in the necropolis, including mound XI (K). In general the results confirm the earlier assumed chronology of the site - the 14C AMS dates fit the timeframe – the central grave fits ideally the previous timeframe for the Brezjak culture, i.e. the 15th and 14th century BC, and all of the amber samples are definitely of Baltic origin. These two facts clearly suggest that the amber finds from the lower Drina could mark one of the earliest appearances of Baltic amber in the Central Balkans.

Evaluation of Fossil Amber Birefringence and Inclusions Using Terahertz Time-Domain Spectroscopy.

Using a cross-polarization transmission geometry, stress maps for the normalized birefringence and intrinsic stress direction of polymeric materials may be obtained using terahertz nondestructive evaluation. The analysis method utilizes a deconvolution method to determine the arrival times and amplitude of the cross-polarized terahertz pulses through a birefringent material. Using amber (a naturally occurring polymer) as a material of interest, stress maps show that inclusion-free Lebanese amber samples behave as classic uniaxial birefringent (photoelastic) materials whose principal stress directions, as inferred in the terahertz spectral range, agree well with visible photoelasticity measurements. Since amber samples, depending upon their source, may be either transparent or opaque to visible light, comparing birefringence measurements in the visible and terahertz spectral ranges cross-validates the stress measurements, thereby establishing a strong and unique stress analysis methodology for visibly opaque samples. While the material of interest for this paper is amber, the method is generally applicable for any terahertz-transparent polymer. The cross-polarization experimental configuration enables stress levels within the amber matrix to be visualized while also outlining highly localized regions of stress surrounding inclusions. Birefringence stress maps clearly show localized increases in stress magnitude and directional changes surrounding inclusions.

Microfossils in resin from the middle Eocene Buchanan Lake Formation, Napartulik, Axel Heiberg Island, Nunavut, Canada

During the warm middle Eocene (ca 45 Ma), the Napartulik area (also called ‘the Geodetic Hills’), Axel Heiberg Island, northern Canada (Nunavut), was vegetated with mixed broad-leaved deciduous angiosperm and evergreen conifer forests over extensive floodplain and forested wetland habitats. Massive organic rich sedimentary successions and encapsulated in-situ tree trunks suggest these forests were drowned by frequent flooding events. The sedimentary layers contain sub-fossil amber that was produced by representatives of the Pinaceae such as Pseudolarix. The amber offered an opportunity to investigate aerial plankton and thus the chance to discover microfossils, which could provide evidence of biotic interactions associated with, or the cause of, the forest die-offs. Fifty-four amber samples were subjected to a solvent treatment for microfossil extraction followed by light microscopy, resulting in the discovery of several hundred microfossils. Unexpectedly, one-quarter of the microfossils were diatoms, which may predominantly have lived on the tree bark. Fungal spores were rare, and the pollen grains found corroborated earlier findings in litter or coal. The records of fungal spores and arthropod remains were insignificant and could, therefore, not substantially have been contributing to the forest die-offs. More resin analyses from the complete sedimentary profile would be needed to get a clearer picture of putative forest pests and prevailing environmental conditions

Evaluation of natural ageing responses on Burmese amber durability by FTIR spectroscopy with PLSR and ANN models

Amber ageing is an inevitable process, which is very important in precious organic gemstone relics protection. In order to explore the mechanism of amber ageing and estimate the durability of Burmese amber, this research investigates the changing spectral features of Burmese ageing amber via Fourier Transform Infrared Spectroscopy (FTIR) and solid 13C Nuclear Magnetic Resonance spectroscopy (NMR) and develops the regression models for its micro-hardness by micro-FTIR spectra. The Partial Least Squares Regression (PLSR) and Artificial Neural Networks (ANN) methods as well as Competitive Adaptive Reweighted Sampling (CARS) algorithm for wavelength variables selection have been applied to predict and assess the Vickers hardness of amber samples with different ageing degrees. As a result, the FTIR and the solid 13C NMR spectra reveal that the contents of CO groups (of esters) increase substantially, and which of the other oxygenic groups (CO (of acids), COC, COCC) increase modestly in amber ageing. When comparing with the results of four different models (PLSR, ANN, CARS-PLSR and CARS-ANN), the CARS-PLSR model obtained the optimal results as follows: the squared correlation coefficient of calibration(R2cal) is 0.9230 and the root mean square error of calibration (RMSEC) is 1.2977 HV; the squared correlation coefficient of prediction (R2pre) is 0.7762 and the root mean square error of prediction (RMSEP) is 2.2208 HV. The overall results sufficiently demonstrate that FTIR spectroscopy technique coupled with appropriate chemometrics methods are very promising tools to estimate and predict the hardness property of Burmese ageing amber.

Fourier transform infrared spectroscopy (FTIR) characteristics of ancient amber artifacts of the Han Dynasty from Hunan, China

Here we analyze four ancient amber artifacts of the Han Dynasty (202 BCE–220 CE) by using Fourier transform infrared spectroscopy to reveal their origins. The FTIR results showed the presence of the Baltic shoulder band between 1210–1150 cm-1 and the weak absorption peak near 888 cm-1, so all amber artifacts analyzed here can be classified as succinite originating from the Baltic Sea area (or also Bitterfield or Ukrainian ambers which are Baltic amber coevals). Ancient amber could have been traded from the Baltic area to the Mediterranean via the amber road, and then to the East Asia along the Silk Road. Such exotic materials represent a key for the study of long-distance trade across cultures during ancient times. Very few ancient amber samples excavated in China have been analyzed scientifically so far, and more work is required.

Method of price formation of amber samples on the basis of gemmological-consumer indicators


 
 
 Analysis of existing systems for expert grading of amber samples showed that their main disadvantages are, in general, consideration of only standard quality criteria (weight, colour, inclusions), as well as the lack of evaluation of rare and unique samples. Today in Ukraine there is, in fact, a state monopoly of pricing in the form of an official price-list for raw amber, developed by the State Gemmological Center based on the global market prices. The authors believe that this document does not fully take into account the costs associated with exploration, mining and taxation on the amber market. This deprives the direct users of the amber-bearing areas themselves of the opportunity to determine the criteria for the quality of rough amber and to develop the corresponding price lists. The created method of gemmological-consumer indicators allows for a transparent and understandable formation of the cost of individual amber samples. The value of raw amber determined in this way corresponds to the consumer values of the product, not taking into account processing costs. The sum of consumer properties of amber in items (shape, size, colour, transparency, presence of inclusions, quality of processing – polishing, artistry, etc.) is taken into account, thus satisfying the physiological and aesthetic needs of consumers for the product. To make the consumer properties of amber identifiable, it is necessary to provide the sample with a marketable condition. The criteria for the quality of amber in products have been developed. It is shown that each type of product is characterized by a set of properties that are criteria for product quality. In fact, this is a tool with which one can determine the type of product in the raw material, having previously determined its quality. Comparing the obtained data on the quality of raw materials with the criteria for the quality of products, it is possible to predict the type of product. The operation of the technique is illustrated by examples of two samples of amber containing inclusions. A method for determining the cost of individual samples of amber has been developed, the essence of which is the sequential fixation of gemmological and consumer properties of the sample with their subsequent transformation into an alphanumeric code, the total value of which forms an individual indicator of the sample (a set of individual qualities of the sample), which correlates with its cost. During the expert assessment of rare and unique samples of amber, their scientific, collection, aesthetic and artistic features must additionally be taken into account, establishing the uniqueness of these objects of examination. The method is designed for the symbiosis of individual natural (gemmological) parameters of the sample (size, beauty, presence of inclusion) with a set of consumer properties: shape, size, weight, colour, transparency, fracturing, presence of inclusion, presence of inclusions, polishability, value for science, collection, artistry, etc. The method covers the entire life cycle of amber from raw material to the final product, for which the sample is chosen as optimal in terms of economic, technological and gemmological-consumer indicators.
 
 

Non-destructive comparative evaluation of fossil amber using terahertz time-domain spectroscopy.

Fossilized plant resins, or ambers, offer a unique paleontological window into the history of life. A natural polymer, amber can preserve aspects of ancient environments, including whole organisms, for tens or even hundreds of millions of years. While most amber research involves imaging with visual light, other spectra are increasingly used to characterize both organismal inclusions as well as amber matrix. Terahertz (THz) radiation, which occupies the electromagnetic band between microwave and infrared light wavelengths, is non-ionizing and frequently used in polymer spectroscopy. Here, we evaluate the utility of amber terahertz spectroscopy in a comparative setting for the first time by analyzing the terahertz optical properties of samples from 10 fossil deposits ranging in age from the Miocene to the Early Cretaceous. We recover no clear relationships between amber age or botanical source and terahertz permittivity; however, we do find apparent deposit-specific permittivity among transparent amber samples. By comparing the suitability of multiple permittivity models across sample data we find that models with a distribution of dielectric relaxation times best describe the spectral permittivity of amber. We also demonstrate a process for imaging amber inclusions using terahertz transmission and find that terahertz spectroscopy can be used to identify some synthetic amber forgeries.

Organic inclusions in Brazilian Cretaceous amber: The oldest ostracods preserved in fossil resins

Fossil resins and ostracods are well-known in Brazilian Cretaceous sedimentary Basins, especially in the Araripe Basin. The present work reports several ostracods encapsulated in an amber sample recovered from limestones of the Crato Formation (Araripe Basin, Northeastern Brazil). The amber was analyzed under optical and eletronic microscopy revealing several ostracod specimens. Considering the general morphology, the recovered specimens were attributed to the freshwater to brackish genera Pattersoncypris Bate, 1972 and Damonella Anderson, 1966 in the superfamily Cypridoidea. Additionally, palynological analyses of the limestone rock around the amber demonstrate the predominance of pollen grains of the Classopolis genus, produced by conifers of Cheirolepidiaceae family, suggesting this family as possible botanical source of the fossil resin. The proposed interpretation for this preservation is as follow: (i) the lake level variations transported the ostracods to the margin; (ii) drops of resin exuded from the trunk fell to the margin on the dead ostracods; (iii) the exposed resin underwent polymerization preserving the ostracods; (iv) and finally, the amber was preserved in the laminated calcareous deposit. The record described here provides a detailed study of organisms fossilized in Brazilian amber as well as it reports the oldest record of ostracods enclosed in fossil resins (Aptian age).

Petrographical-geochemical characteristics and floral-faunal compositions of the Valia lignite deposits from Cambay Basin (Gujarat), western India

Lignite-bearing sequence of the Valia mine, associated with the Cambay Shale Formation (early Eocene) in Cambay Basin of western Indian State Gujarat, has been studied. An integrated approach (including organic petrography, palynofacies, palynology, entomology, geochemistry) has been adopted to assess the origin and characters of lignite deposits and their potential for the hydrocarbon generation, besides to understand the evolution and interaction of different biotic (floral-faunal) groups of the geological time. The studied samples (lignites/shales) are characterized by the domination of huminite group (av. 67 vol.%)/phytoclasts (av. 58%) along with the abundance of short-chain n-alkanes (bacterial activity). The frequencies of detrohuminite sub-group, non-biostructured elements, macrophyte-derived amorphous organic matter (AOM, mainly), and high values of proxy aqueous are indicating the elevated bacterial degradation of the OM and/or also suggest the significant contribution of the herbaceous vegetation/aquatic macrophytes/algal input to the palaeo-peat. The relative abundance of hopanes and low values of the steroids/hopanoids ratios further indicate a high bacterial activity. On the other hand, the contents of telohuminite, liptinite group, and cuticle elements together with the high carbon preference index, low proxy wax, and terrigenous/aquatic ratios confirm both terrestrial and macrophyte contributions during the peat accumulation. Fascinatingly, we have found Dipterocarpus-derived amber (fossil resin) within the lignite seam (lower) with remarkably well-preserved arthropod inclusions consisting of arachnids and insects. Generally, insects have an association with flora and provide important ecosystem functions. In the studied amber samples, the insects to arachnids (spiders and pseudoscorpions) ratio is 3:1. Their quantitative analysis indicates the dominance of the Chironomidae (non-biting midges 32%) followed by Araneae, Myrmicinae, Cecidomyiidae, and Mycetophilidae. A rare entity such as pseudoscorpions has also been found during the investigation.The derived petrographic indices indicate that the peat-forming limno-telmatic vegetation was accumulated mainly in back-barrier settings with high groundwater (mesotrophic to rheotrophic) condition. The contents of pyrite (mainly framboidal) mineral and sulphur (0.69–2.24 wt.%) suggesting that peat had experienced the marine influx. Further, the high occurrence of funginite maceral (among inertinite group), and spores of family Microthyriaceae point towards a warm and moist condition. The plotting of palynofacies data on Tyson's APP diagram, and the values of pristane/phytane ratio suggest that the OM was primarily deposited in dysoxic to suboxic settings. The high incidence of family Chironomidae, non-biostructured and low cuticle contents indicate the proximal settings and a low energy environment like lake/pond or marshlands. However, the occurrence of granular-AOM along with high (relatively) opaque phytoclast contents in the upper part indicates that distal settings were formed at the termination of the OM accumulation. The total organic carbon (TOC) contents and hydrogen index values in the studied samples indicate a good to excellent source for the hydrocarbon generation. However, the low gross calorific value (av. 4467 cal/g), values of Tmax (mostly below 435 °C), and H/C and O/C atomic ratios showing that the samples are of immature (early diagenetic stage; huminite reflectance value: av. 0.28%) nature of the OM. Moreover, the different cross plots (hydrogen index (HI) vs. oxygen index (OI), S2vs. TOC, HI vs. Tmax) indicate that the Valia lignite-bearing succession contains admixed type-III/II kerogen, and can generate gaseous and some liquid hydrocarbons upon maturation or with additional heating.

Molecular Simulation of Resin and the Calculation of Molecular Bond Energy.

In this study, average structural characteristics of amber were researched and used as an example to establish the three-dimensional (3D) average structure of resin. Two coal samples containing solid amber were collected from Fushun and Hunchun in Northeast China, from which pure amber samples were separated and resin was extracted. Solid-state nuclear magnetic resonance (13C NMR) spectroscopy was used to obtain structural information of amber, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry was performed on the resins to determine their molecular mass. The results of these studies revealed that the average structure of amber was dominated by cycloalkane, with a small amount of aromatic carbon, and there were almost no aliphatic chains in the structure. The molecular masses of the compounds in the resin were mainly in the range 99–750 Da, and the average molecular mass was ∼370 Da. To characterize the resin chemical structure, two 3D molecular models based on density functional theory were established taking amber as the example, and the relevant molecular bond energies were calculated. Based on these models, the interactions among the components in oil were studied, and the binding energies of the different molecules were calculated. In summary, in this study, amber was used as a medium to establish an accurate molecular model of resin and proved that compared to hydrocarbon compounds, resin molecules were more likely to interact with bitumen.

Hardness of as-synthesized cubic boron nitride (111) bulk single crystals

The cubic boron nitride is the second most important superhard materials. To date, the effect of crystallographic anisotropy of the {111} plane on the Knoop microhardness of cubic boron nitride single crystals has not been experimentally obtained. Herein, we measure the detailed Knoop hardness and Vickers hardness for the {111} plane of the amber cubic boron nitride. We find that the crystal orientation dependence of Knoop hardness for amber samples is remarkable and has an obvious regular pattern. The Knoop hardness for amber samples shows a minima about 5° from ⟨110⟩ directions, which is different from the traditional viewpoint that the minimum hardness is on ⟨110⟩ directions. Raman spectra of cubic boron nitrides are measured and help us to explain the hardening of samples.

Volatile and semi-volatile composition of Cretaceous amber

Chemical analysis of amber, copal, and resin is a valuable tool for interpreting the botanic origin of amber and the ecological role of resin in ancient forests. Here we investigated for the first time the volatile and semi-volatile composition of Cretaceous amber, as well as copal and Defaunation resin produced by trees of the family Araucariaceae (Gymnospermae: Pinidae), via solid-phase microextraction gas chromatography-mass spectrometry. Principal component analysis (PCA) revealed a clear distinction between the Pleistocene copal/Defaunation resin and the much older Cretaceous amber samples. However, even among the younger resin samples whose plant producers were identified to the species level, the PCA did not clearly distinguish the groups, either at the species level or at the genus level. Therefore, even with ideal preservation of original chemistry, PCA of SPME GC/MS data will not differentiate varying botanic origins in the Cretaceous amber samples. There was extensive variation observed in the composition of the amber samples, but no separate groups in the PCA. This amber chemistry was most likely influenced by multiple factors, such as variable original resin chemistry and variable maturation as the most relevant. The Cretaceous amber deposits are proposed to represent forests with multiple taxa (even multiple families) of resin-producing trees, which varied over space and time, rather than representing a widespread and homogenous forest. As resin composition is strongly affected by both taxonomy of the resin-producing tree and ecological factors such as herbivory and pathogens, we propose that these forests were exposed to varying combinations of ecological factors.

Electrostatics and Electrochemistry: Mechanism and Scope of Charge-Transfer Reactions on the Surface of Tribocharged Insulators.

The phenomenon of surface electrification upon contact is a long-standing scientific puzzle, with for instance written accounts of charged samples of amber attracting feathers dating back to the 600 B.C. Electrostatic hazards associated with electrical insulators subject to mechanical friction are well documented, and the design of commercial products, such as copiers and laser printers, is based on the static charging of electrical insulators. Nonetheless, the physical-chemical origin of this phenomenon remains debated. This Perspective outlines recent advances in our understanding of the mechanism behind contact electrification, as well as the emerging research area of electrochemistry on insulators. Research is beginning to demonstrate how to exploit static charges present on insulating surfaces, with the goal of driving redox reactivity. These studies have helped to clarify the triboelectrification mechanism and have defined new platforms for electrochemiluminescence, metal nucleation, and mask-free lithography. This Perspective will help researchers working within electrochemistry, physics, green energy, sensing, and materials to gain an understanding of the implications of contact electrification to their respective fields. Special attention is given to the chemical, electronic, and mechanical factors influencing triboelectrochemical reactions, concluding with the perceived challenges facing further development of this field.

Burmese Amber Compared Using Micro-Attenuated Total Reflection Infrared Spectroscopy and Ultraviolet Imaging.

Attenuated Total Reflection (ATR) spectroscopy coupled with a microscope allows for the analysis of specimens without any preparation, spatially correlated with the morphology of the specimen. These characteristics make micro-ATR systems very useful for studying gemstones and in particular amber samples. Indeed, in this report, the micro-ATR technique was used to characterize three Burmite samples, as case studies. Particularly, focusing the ATR crystal spot on the amber surface where a difference in the Ultraviolet (UV) reaction was previously detected, thereby relative differences in the IR spectrum could be analyzed. Here we present a methodology combining the UV imaging technique with the micro-Attenuated total reflection Fourier transform infrared spectroscopy (micro-ATR/FT-IR) analyses, in order to correlate the fluorescence information with the molecular vibrational modes of amber and their relative spatial distribution. Finally, this work is intended as an initial methodology study and part of the amber characterization project, focused on characterizing the Burmese amber collection of the Peretti Museum Foundation from several disciplines (i.e., palaeoentomology, vibrational spectroscopy, neutron tomography, etc.).