Micro-infrared Spectroscopy Research Articles

Fabrication of metal-organic frameworks containing Cu2+ coated medical PVC catheters with durable antiplatelet and antibacterial activities

Polyvinyl chloride (PVC) catheters are widely used in medical environments especially in blood-contacting devices. In this study, a copper containing MOF material was coated on a PVC catheter to endow it with antiplatelet adhesion and antibacterial activity for potential clinical applications. The immobilization of the coordination polymer containing Cu2+ (Cu-MOF) on the inner surface of PVC catheters was carried out using a bioinspired coating combined with a layer-by-layer self-assembly strategy. Characterization of the Cu-MOF modified surfaces was confirmed using micro-infrared spectroscopy (MIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and water contact angle measurements (WCA). The resultant modified surfaces significantly reduced non-specific adsorption to model proteins with excellent anti-biofouling activity, as well as significantly inhibited the platelet adhesion and activation with superior antiplatelet activity. In vitro whole blood circulation test using a peristaltic pump also showed good antithrombotic properties. Besides, the Cu-MOF modified surfaces exhibited good hemocompatibility (hemolysis ratio < 5 %) and excellent antibacterial activity (approximately 97 % against S. auerus and E. coli). This study develops a simple and effective method for the surface modification of medical PVC catheter as potential blood-contacting biomaterials.

Distribution characterization of MPs and DOM in ice-covered season in a saline-alkaline Lake in Daihai with an innovative analysis using 2DCOS and structural equation modelling

Due to the characteristics of low density, light weight, and strong hydrophobicity, microplastics (MPs) can adsorb dissolved organic matter (DOM) in lake water to jointly accomplish migration and transformation in the ice/water medium, which causes serious pollution to the lake during the ice period through accumulation. In this study, the distribution of Daihai Lake MPs and DOM was studied by fluorescence excited emission matrix (EEM) and micro-infrared spectroscopy, and the relationship between them was examined by two-dimensional correlation spectroscopy (2DCOS) and structural equation modelling (SEM) to obtain the influencing factors of pollution. The results indicate that the concentration of MPs in the surface ice layer is 1.35 times more than in the water and in the surface and bottom ice layers 1–2 times more than the middle layer. DOM in the ice cover is mainly protein-like (73.33%), and humus-like DOM (44.8%) is dominant in the water under the ice that is consistent with the distribution of MPs in the ice and water layer. As a result, MPs are more prospective to adsorb humus-like substances into the ice during migration. Through SEM analysis, it was concluded that human activities and the degree of economic development seriously affect the pollution level and the type of MPs and DOM in lakes. One of the most important factors in winter is the ice cover, and there is a strong correlation between the MPs and DOM in different ice layers. Combined with experimental data, it was concluded that the ice layer influences the distribution characteristics of the pollutants in lakes as well as the direction of migration. However, the adsorption mechanism of the ice is not clear, which will be a key direction for future research on microplastics in ice-covered lakes.

Study on the inhibition of dexmedetomidine (DEX) on malignant development of breast cancer by synchrotron radiation infrared spectroscopy

ObjectivesThe topic of the relationship between analgesia and cancer recurrence inoncology surgery is a subject of debate in the field. Administering analgesic drugs after breast cancer surgery could potentially impact the long-term outcomes for patients. During breast cancer surgery, DEX, a potent α2 adrenergic receptoragonist, is often administered as an analgesic. Despite its common use, the analgesic effect of DEX and its potential impact on the progression of breast cancer remain uncertain. MethodsTo investigate the impact of DEX on breast cancer cells, cells exposed to DEX were collected and analyzed through cell apoptosis detection and synchrotron radiation micro-infrared spectroscopy. ResultsFollowing DEX treatment, the absorption peaks of MDA-MB-231 and MCF-7 cell lines showed significant redshift at 1230–1250 cm−1 and 1380–1420 cm−1 bands (p<0.05). The absorption peak in the 1500–1700 cm−1 band decreased (p<0.05), while the 2910–2990 cm−1 absorption peak increased, along with other apoptotic characteristics (p<0.05). Our cell experiment results demonstrated that DEX was capable of protecting cell immunity via the down-regulation of TLR-4 receptor and effectively hindered the growth of breast cancer cells. ConclusionThe cell and spectrum experiments' results indicate that DEX can encourage tumor cell apoptosis. These findings suggest that DEX is safe to use for breast cancer surgery and pain management.

Mineralogical classification and crystal water characterisation of beryl from the W–Sn–Be occurrence of Xuebaoding, Sichuan province, western China

AbstractBeryl from Xuebaoding, Sichuan Province, western China is known for its unusual tabular habit and W–Sn–Be paragenesis in a greisen-type deposit. The crystals are typically colourless transparent to pale blue, often with screw dislocations of hexagonal symmetry on the (0001) crystal faces. Combining electron microprobe analyses and laser ablation inductively coupled plasma mass spectrometry with single-crystal X-ray diffraction (XRD), correlated with Raman and micro-infrared (IR) spectroscopy and imaging, the crystal chemical characteristics are determined. The contents of Na+ (0.24–0.38 atoms per formula unit (apfu)) and Li+ up to 0.38 apfu are at the high end compared to beryl from other localities worldwide. Li+ substitution for Be2+ on the tetrahedral (T2) site is predominantly charge balanced by Na+ on the smaller channel (C2) site, with Na+ ranging from 91.5% to 99.7% (apfu) of the sum of all other alkali elements. Cs+ and minor Rb+ and K+ primarily charge balance the minor M2+ substitution for Al3+ at the A site; all iron at the A site is suggested to be trivalent. The a axis ranges from 9.2161(2) to 9.2171(4) Å, with unit-cell volume from 678.03(3) to 678.48(7) Å3. The c/a ratio of 1.0002–1.0005 is characteristic for T2-type beryl with unit-cell parameters controlled primarily by Be2+ substitution. Transmission micro-IR vibrational spectroscopy and imaging identifies coordination of one or two water molecules to Na+ (type IIs and type IId, respectively) as well as alkali free water (type I). Based on IR absorption cross section and XRD a C1 site water content of 0.4–0.5 apfu is derived, i.e. close to 50% site occupancy. Secondary crystal phases with a decrease in Fe and Mg, yet increase in Na, suggest early crystallisation of aquamarine, with goshenite being late. With similar crystal chemistry to beryl of columnar habit from other localities worldwide, the tabular habit of Xuebaoding beryl seems to be unrelated to chemical composition and alkali content.

Synthesis of a Series of Dual-Functional Chelated Titanate Bonding Agents and Their Application Performances in Composite Solid Propellants.

Titanate-based bonding agents are a class of efficient bonding agents for improving the mechanical properties of composite solid propellants, a kind of special composite material. However, high solid contents often deteriorate the rheological properties of propellant slurry, which limits the application of bonding agents. To solve this problem, a series of long-chain alkyl chelated titanate binders, N-n-octyl-N, N-dihydroxyethyl-lactic acid-titanate (DLT-8), N-n-dodecyl-N, N-dihydroxyethyl-lactic acid-titanate (DLT-12), N-n-hexadecyl-N, N-Dihydroxyethyl-lactic acid-titanate (DLT-16), were designed and synthesized in the present work. The infrared absorption spectral changes of solid propellants caused by binder coating and adhesion degrees of the bonding agents on the oxidant surface were determined by micro-infrared microscopy (MIR) and X-ray photoelectron spectroscopy (XPS), respectively, to characterize the interaction properties of the bonding agents with oxidants, ammonium perchlorate (AP) and hexogen (RDX), in solid propellants. The further application tests suggest that the bonding agents can effectively interact with the oxidants and effectively improve the mechanical and rheological properties of the four-component hydroxyl-terminated polybutadiene (HTPB) composite solid propellants containing AP and RDX. The agent with longer bond chain length can improve the rheological properties of the propellant slurry more significantly, and the propellant of the best mechanical properties was obtained with DLT-12, consistent with the conclusion obtained in the interfacial interaction study. Our work has provided a new method for simultaneously improving the processing performance and rheological properties of propellants and offered an important guidance for the bonding agent design.

Optical-vibration properties of Li2ZnGeO4 dielectric ceramics

This work reports on the optical-vibration properties of Li2ZnGeO4 ceramics prepared by solid-state reactions. Single-phase, high-purity materials belonging to the monoclinic P21/n space group were obtained. Micro-Raman scattering and micro-infrared spectroscopy, besides group-theory calculations, were employed to determine and assign the phonon modes. Polarized Raman scattering was able to discern and assign a total of 36 modes, in good agreement with theoretical predictions (48 phonons were foreseen). Micro-infrared spectroscopy in the frequency range 50−4000 cm−1 was applied on sintered, polished samples and a total of 30 polar modes were identified (among the 45 infrared modes predicted by group-theory calculations). Detailed dispersion analyses were conducted by using Kramers-Krönig relations as well as the Lorentz model. Intrinsic dielectric constant and quality factor were calculated as 6.2 and 387 THz, respectively. The promising results obtained in the present work showed that monoclinic Li2ZnGeO4 ceramics are suitable for applications in wireless communication devices.

One-pot synthesis of bio-supported Pd nanoparticles by using clove leaf and their catalytic performance for Suzuki coupling reaction

Bio-supported palladium nanoparticles (PdNPs/RCL-b) were synthesized by one-pot method without adding any chemical reducing and stabilizing agents. In the preparation process, Clove leaf (CL) was used as carrier, reducing and stabilizing agents. The extraction of reducing compounds from CL, the reduction and stabilization of Pd2+, and palladium nanoparticles (PdNPs) loading on the extraction residue of CL (RCL) were accomplished simultaneously, avoiding the agglomeration of PdNPs and ensuring PdNPs loading evenly on RCL. The prepared PdNPs/RCL-b catalysts were characterized by XRD, UV–Vis, Micro-infrared spectroscopy, FT-IR and TEM. The hydroxyl groups and other reductive groups which exist in polyphenols and flavonoids reduced Pd2+ to PdNPs, while the CO, C–O and other groups containing O served as good protective agents and stabilizers for the formation of PdNPs. The PdNPs had a face-centered cubic structure with a particle size distribution of 1.26–8.78 nm and an average particle size of 4.49 nm, and uniformly dispersed on the surface of RCL. The results of catalytic Suzuki coupling reaction between 4-bromonitrobenzene and phenylboronic acid over PdNPs/RCL-b at 60 °C showed that the yield was 96.22% for 20 min and the value of TOF was 5773.2 h−1. After the reaction between 4-bromotoluene and phenylboronic acid repeated for 8 times, the yield remains above 91%. This method provides a more facile, efficient and green approach to the preparation of supported nano-palladium catalysts.

Chemical mapping analysis of compatibility in gelatin and hydroxypropyl methylcellulose blend films

Blending different polymers for composite formulations can improve the functionalities of the products. The compatibility between hydroxypropyl methylcellulose (HPMC) and gelatin was studied using Chemical mapping analysis such as synchrotron micro-infrared spectroscopy (μSR-FTIR) and confocal Raman microscopy. The interface and phase composition of the blend films with varying ratios of gelatin and HPMC were analyzed in detail. It was found that the distribution patterns of continuous matrices and dispersed phases changed with varying concentrations of the components. Raman spectroscopy based imaging analysis showed that HPMC easily aggregated to form continuous phases. Both μSR-FTIR and Raman microscopic analysis confirmed the existence of intermediate phases in the composites from the molecular interactions between the two components. Overall, the Chemical mapping techniques were useful to study the phase composition of composites of polysaccharides and proteins.

Effect of LPHT annealing on interface characteristics between HPHT Ib diamond substrates and homoepitaxial CVD diamond layers

Abstract

Release of Ceramide Molecules from Ceramide-Containing UV-curable Acrylic Adhesive Gel Sheet Affixed to Human Skin

Ceramide, an intercellular lipid of the stratum corneum, plays an essential role in making the skin barrier. One problem with the use of medical adhesive tape or sheets for skin is that their repeated attachment and detachment may cause some damage to the skin. An attempt has been made to eliminate this problem by mixing ceramide into the adhesive of sheets, and has delivered excellent clinical results. This study aimed to investigate whether ceramide is transferred from the adhesive with added ceramide to the skin. An adhesive sheet was prepared by adding synthetic ceramide (CER) to UV-curable acrylic adhesive gel. After affixing the adhesive sheet to human skin for a certain period, it was peeled off and cut perpendicular to the adhesive surface. Synchrotron micro-infrared spectroscopy of the sectioned samples showed that the ceramide concentration in the gel sheet decreases as the application time to human skin increases. This is thought to be due to the release of CER from the gel sheet.

In situ Study on the Diffusion Kinetics of Seal Ink by Microinfrared Spectroscopy.

In document examination, it is of great importance to determine the composition of seal ink with different imprint times, and spectroscopic methods are widely used today. In this research, the diffusion of seal inks from three different brands on the same type of paper is monitored insitu by microinfrared spectroscopy and microinfrared imaging technology. The area of the absorption peak at 1743cm-1 gradually decreases with increasing diffusion time. The diffusion kinetics of seal ink on paper are also studied by analyzing the infrared spectra of seal inks at the same measuring point with different diffusion times. The research provides a basic study in understanding the diffusion behavior of seal ink on paper over short time spans.

High-throughput NIR spectroscopic (NIRS) detection of microplastics in soil.

The increasing pollution of terrestrial and aquatic ecosystems with plastic debris leads to the accumulation of microscopic plastic particles of still unknown amount. To monitor the degree of contamination, analytical methods are urgently needed, which help to quantify microplastics (MP). Currently, time-costly purified materials enriched on filters are investigated both by micro-infrared spectroscopy and/or micro-Raman. Although yielding precise results, these techniques are time consuming, and are restricted to the analysis of a small part of the sample in the order of few micrograms. To overcome these problems, we tested a macroscopic dimensioned near-infrared (NIR) process-spectroscopic method in combination with chemometrics. For calibration, artificial MP/ soil mixtures containing defined ratios of polyethylene, polyethylene terephthalate, polypropylene, and polystyrene with diameters < 125μm were prepared and measured by a process FT-NIR spectrometer equipped with a fiber-optic reflection probe. The resulting spectra were processed by chemometric models including support vector machine regression (SVR), and partial least squares discriminant analysis (PLS-DA). Validation of models by MP mixtures, MP-free soils, and real-world samples, e.g., fermenter residue, suggests a reliable detection and a possible classification of MP at levels above 0.5 to 1.0 mass% depending on the polymer. The benefit of the combined NIRS chemometric approach lies in the rapid assessment whether soil contains MP, without any chemical pretreatment. The method can be used with larger sample volumes and even allows for an online prediction and thus meets the demand of a high-throughput method.

Concoction Component Analysis of Electrical Treeing in Polyethylene by Micro-Infrared Spectroscopy

Regular infrared spectroscopy is utilized to research the debasement locale after electrical treeing in polymers. Be that as it may, the measurement of the infrared light spot is too vast contrasted and the tree channel and the position of the light spot is uncertain. Thusly, the smaller scale infrared spectroscopy is proposed in this paper, which is plan to do synthetic investigation for electrical tree range in polyethylene at a micrometer scale. An inclined air conditioning voltage was connected for electrical tree initiation in polyethylene, using a wire-plane terminal structure. Cuts of tests with electrical trees were then examined through small scale infrared spectroscopy. The trademark bunch dispersion inside a chose treeing zone was given through smaller scale infrared mapping. The examination comes about demonstrated the presence of C=O, C-OH and C-O-C gatherings, and the substance of C-OH and C-O-C gatherings was more than C=O gathering. The presence of C=O gathering was went with the C-OH gathering, and the last absorbance is higher, so it is construed the C=O assemble have a tendency to debase additionally as per the Norrish sort II administration. What's more, not all the electrical tree region had the oxygen containing gatherings. The material corruption amid electrical treeing was examined with and without oxygen.

Lead soaps in paintings: Friends or foes?

The origin(s) and role(s) of metal soaps in paints are a worldwide concern today. These hybrid compounds, containing both fatty acid chains and metals associated with a carboxylate function, are increasingly identified in paints. As reviewed in the first part of this work, the presence of metal soaps in paints is differently interpreted in scientific publications: metal soaps are sometimes considered to play a positive role as anchor points, during paint drying processes; they can also be considered as responsible for many degradation processes (protrusions, efflorescences, darkening, etc.). Their origins are also interpreted in various ways. In some paintings (in particular from the twentieth century), they have sometimes introduced on purpose, as additives, to modify the physical properties of the painting materials. In older paintings, metal soaps are usually thought to result from an uncontrolled reaction of oil with lead-based pigments, in particular lead white, red lead, and lead tin yellow. In the second part of this work, the review of historical recipes of lead-based paint shows an important number of recipes based on controlled mixing of oil with lead driers. In the third part, the experimental reproduction of such traditional recipes using walnut oil and litharge (PbO) shows that lead soaps can be formed, both in about one hour at ∼100°C, or in about one month at room temperature. It shows as well that after a few years, litharge is no longer detected in the paint medium, while different lead carbonates are. Finally, the micro-infrared spectroscopy and micro-X-ray diffraction re-analysis of protrusions from a nine-year model painting shows together with lead soaps, the presence of Pb5(CO3)3(OH)2O (‘synthetic plumbonacrite’), an unusual phase recently observed in a protrusion from a painting by Vincent Van Gogh. This work highlights (i) the multiple origins and roles of metal soaps in paints and (ii) the importance of combining the analysis of fragments from historical paintings with the analysis and reproduction of historical recipes. In particular, we show that the components detected today in historical paintings may severely differ from those originally used or prepared by the painter, complicating the assessment of the painter's intentions. More than the presence of metal soaps, the key questions to be tackled should be about their origins and (re)mobilization.

Analytical investigation of Mudéjar polychrome on the carpentry in the Casa de Pilatos palace in Seville using non-destructive XRF and complementary techniques

The pigments, execution technique and repainting used on the polychrome wood ceilings and doors in the Casa de Pilatos (Seville, Spain) were studied using portable X-ray fluorescence equipment. Cross-sections of small samples were also analysed by optical microscopy, SEM with EDX analysis, micro-Raman and micro-infrared spectroscopy and X-ray diffraction. These carpentry works are magnificent examples of the Mudéjar art made in Spain in the early 16th century. Portable X-ray fluorescence gave good information on the different components of the polychrome. The SEM-EDX study of the surfaces of small samples gave information on their components and also characterized the compounds that had been deposited or formed by environmental contamination or by the alteration of some pigments. The SEM-EDX study of cross-sections facilitated the characterization of all layers and pigments from the support to the most external layer. The following pigments were characterized: red (cinnabar/vermillion, lead oxide, iron oxides and orpiment/realgar), black (carbon black), white (white lead and titanium barium white), yellow-orange-red-brown (orpiment/realgar and iron oxides), green (chromium oxide), blue (indigo blue and ultramarine blue), and gilding (gold leaf on bole). False gold, bronze and brass were also found. The pigments were applied with the oil painting technique over a support layer that had been primed with animal glue. This support layer was gypsum in some cases and white lead in others. This study is essential to the polychrome conservation of the studied artwork, and it will help clarify uncertainties in the history and painting of Mudéjar art.

Chemical component analysis of electrical treeing in polyethylene by micro-infrared spectroscopy

Conventional infrared spectroscopy is used to investigate the degradation region after electrical treeing in polymers. However, the dimension of the infrared light spot is too large compared with the tree channel, and the position of the light spot is imprecise. Consequently, the micro-infrared spectroscopy is proposed in this paper, which is aim to do chemical analysis for electrical tree area in polyethylene at a micrometer scale. A ramped ac voltage was applied for electrical tree inception in polyethylene, utilizing a wire-plane electrode structure. Slices of samples with electrical trees were then analyzed through micro-infrared spectroscopy. The characteristic group distribution within a selected treeing area was provided through micro-infrared mapping. The experiment results indicated the existence of C=O, C-OH and C-O-C groups, and the content of C-OH and C-O-C groups was more than C=O group. The appearance of C=O group was accompanied with the C-OH group, and the latter absorbance is higher, so it is inferred the C=O group tend to degrade further according to the Norrish type II regime. In addition, not all the electrical tree area had the oxygen containing groups. The material degradation during electrical treeing was discussed with and without oxygen.

Low molecular weight organic acid salts, markers of old fungi activity in wall paintings

Micro-Infrared Spectroscopy (μSR-FTIR) and X-ray diffraction (μSR-XRD) with synchrotron light, Gas Chromatography/Mass Spectrometry (CG/MS), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM/EDS) were used to obtain the distribution of calcium salts of low molecular weight organic acids (LMWOA) in micro-layered micro-samples.

Optimal Sample Preparation for the Analysis of Micrometric Heterogeneous Samples.

Precise microanalytical techniques are essential in many fields such as cultural heritage materials, showing complex layered microstructures containing a wide range of materials of diverse nature and hardness. Noninvasive sample manipulation and preparation is required to avoid, as much as possible, sample contamination, which may strongly limit the materials identification. The method proposed consists in the application of thin gold or carbon protecting layers before embedding the samples in synthetic resin for microtoming. The validity and optimal procedure is checked for those materials most often found on the surface of paintings: varnishes (natural resins and wax). An artwork sample is similarly prepared and analyzed by optical microscopy (OM), scanning electron microscopy (SEM/EDS), micro-infrared spectroscopy (μFTIR/μSR-FTIR), and X-ray diffraction (μSR-XRD) with synchrotron light.

Gate-dependent pseudospin mixing in graphene/boron nitride moiré superlattices

Electrons in graphene are described by relativistic Dirac–Weyl spinors with a two-component pseudospin1,2,3,4,5,6,7,8,9,10,11,12. The unique pseudospin structure of Dirac electrons leads to emerging phenomena such as the massless Dirac cone2, anomalous quantum Hall effect2,3, and Klein tunnelling4,5 in graphene. The capability to manipulate electron pseudospin is highly desirable for novel graphene electronics, and it requires precise control to differentiate the two graphene sublattices at the atomic level. Graphene/boron nitride moiré superlattices, where a fast sublattice oscillation due to boron and nitrogen atoms is superimposed on the slow moiré period, provides an attractive approach to engineer the electron pseudospin in graphene13,14,15,16,17,18. This unusual moiré superlattice leads to a spinor potential with unusual hybridization of electron pseudospins, which can be probed directly through infrared spectroscopy because optical transitions are very sensitive to excited state wavefunctions. Here, we perform micro-infrared spectroscopy on a graphene/boron nitride heterostructure and demonstrate that the moiré superlattice potential is dominated by a pseudospin-mixing component analogous to a spatially varying pseudomagnetic field. In addition, we show that the spinor potential depends sensitively on the gate-induced carrier concentration in graphene, indicating a strong renormalization of the spinor potential from electron–electron interactions.

New insights on blue pigments used in 15th century paintings by synchrotron radiation-based micro-FTIR and XRD

The blue pigments used on altarpieces in the 15th century in Catalonia and Crown of Aragon are principally composed of the azurite mineral. To a lesser extent, lapis lazuli, also of mineral origin, was used and occasionally in the background areas and outlining the principal figures, indigo (of vegetal origin) was used for the chromatic preparation layer. Data from several altarpieces belonging to well-known artists of that time are analysed by synchrotron radiation X-ray diffraction (SR-XRD), micro-infrared spectroscopy (μ-FTIR), synchrotron radiation micro-infrared spectroscopy (μSR-FTIR), Raman spectroscopy, and scanning electron microscopy with X-ray microanalysis (SEM-EDS). X-ray diffraction and infrared spectroscopy in association with synchrotron radiation have proven to be especially useful due to the micron-sized spot size, high brilliance and energy tunability, which help to obtain good separation of signals coming from different phases/substances and determine their localization in the various paint layers. The examples presented illustrate the potential of each analytical technique for the identification of the type of material present in the 15th century paintings. Moreover, the natural origin and composition of the pigments and their distribution in the paint layers are determined and some correlations with other contemporary paintings are proposed. Finally, the alteration compounds related to blue pigments are determined in each case.