Attenuated Total Reflection Infrared Research Articles

Internal structural changes in age-related curved hair due to cyclical extension: An IR spectroscopy study.

This study aimed to identify structural changes in age-related curved hair (referred to as "YUGAMI" hair in Japanese) induced by cyclical extension using infrared (IR) spectroscopy coupled with chemometrics, such as multivariate curve resolution (MCR) and two-dimensional correlation spectroscopy (2DCOS). The hair fibres were stretched at a strain level of 0.3-N, and this operation was counted as one cycle and was repeated 500 cycles. Every 25 cycles, IR spectra were obtained using an attenuated total reflection IR (ATR-IR) microscope. The spectra were analysed by MCR to investigate the structural changes of keratin protein inside of the hair. 2DCOS was conducted to investigate the genesis pathway of SO3H in the 1000-1150 cm-1 range and the change in the secondary structure of keratin protein of hair in the 1600-1700 cm-1 range. For age-related curved hair, 0.3-N strain levels increased the CH2 and C=O signals after 125 cycles and the SO3H signal after 225 cycles, but no architectural modifications were observed in straight hair. Two results were obtained from 2DCOS. One was cyclical extension increased the S-SO3H signal, followed by SO3H signal. The other in the 1600-1700 cm-1 range indicated an increase in the secondary structural motif and β-structure after the formation of SO3H. This study shows that the process of internal transformations can be split into three steps in age-related curved hair caused by cyclical extension. The first step is the surface transfer of internal lipids, and the second step is two distinct patterns of disulfide bond cleavage: C-S and S-S fission. The final step is further transformation of the unravelled α-helices into β-structures which occurs above roughly 225 stretched. Our findings can be an effective factor in care the increase of curvature by cyclical extension such as everyday grooming.

Unlocking the access to nature-identical vanillin via isoeugenol ozonation: in situ ATR-IR monitoring and safety evaluation.

The transformation of renewable feedstocks into aromatic chemicals holds immense potential for advancing a green, low-carbon economy and fostering sustainable development. Herein, we present a novel approach for the conversion of isoeugenol, a renewable lignin derivative, into the valuable flavoring agent vanillin, utilizing ozone as an environmentally benign oxidant. The process optimization was significantly enhanced by the integration of in situ Attenuated Total Reflectance Infrared (ATR-IR) monitoring. The introduction of H2O not only accelerated the decay of carbonyl oxides (Criegee intermediates) but also mitigated safety hazards stemming from the vigorous decomposition and heat release of secondary ozonides. Compared to the conventional Thin Layer Chromatography (TLC) method, ATR-IR monitoring demonstrated superior sensitivity and precision in determining the reaction endpoint, leading to a remarkable vanillin yield of 96.86% upon complete conversion of isoeugenol. Additionally, a comparative assessment of the sustainability of our approach with existing methods was undertaken, and valuable recommendations for safety assessments were provided to ensure the inherent safety of chemical engineering reactions. The present study serves as a pioneering effort in facilitating the implementation of a scalable, economically feasible and environmentally sustainable strategy for biomass flavor production, while contributing to the broader adoption of in situ spectroscopic technology within the larger economy.

IR spectroscopy, thermal characterization and X-ray diffraction of Cd microparticles doped PLA/PHA composite films

In this study, shape-memory and biodegradable poly lactic acid (PLA) and poly hydroxy alkanoate (PHA) were mixed in a 1:1 ratio and films were obtained by solvent casting method. Then, cadmium (Cd) microparticles were added to the PLA/PHA blend at different rates and the composite films were prepared using the same method. PLA/PHA/Cd composite films were characterized by Attenuated Total Reflection-Infrared (ATR-IR) spectroscopy, Thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD). Finally, in the study, the crystallinity values obtained from the XRD patterns of the pure blend film and the composite films were compared.

β‐Sheets Orientation in Physisorbed Protein Layers

AbstractPhysisorption of antibodies onto surfaces is a low‐cost, rapid, and effective approach for immobilizing bioreceptors in applications such as bioelectronic sensors. However, there is a prevailing notion that physisorbed protein layers lack structural order, thus potentially compromising their stability and sensitivity compared to antibody films that are covalently attached to the substrate surface. This study demonstrates the preferential orientation of β‐sheets within the secondary structure of protein layers, specifically anti‐immunoglobulin G (anti‐IgG) and bovine serum albumin (BSA), when physisorbed onto gold (Au) thin films. Using polarization modulation infrared reflection‐absorption spectroscopy (PM‐IRRAS) and infrared attenuated total reflection (IR‐ATR) spectroscopy, it has been confirmed that the β‐strands in these protein layers are tilted relative to the surface normal by average angles of 75.3° ± 0.4° for anti‐IgG and of 79.3 ± 0.2° for BSA. These results are obtained by analyzing the orientation of the transition dipole moments (TDMs) associated with the amide I molecular vibrations derived from a comparison between experimental and simulated mid‐infrared spectra assuming isotropically oriented TDMs. The simulations incorporate refractive and absorption index dispersions obtained from the IR‐ATR spectra. Thus obtained findings offer valuable molecular‐level insights facilitating the design and optimization of biofunctionalized interfaces in advanced biomedical and biosensing applications.

Engineered Recombinant Hagfish Intermediate Filament Proteins: Unraveling Domain Roles in Synthetic Fiber Formation and Mechanics.

Hagfish intermediate filament (HIF) proteins, consisting of α and γ subunits, have been previously recombinantly expressed, purified, and utilized to form dry fibers with impressive mechanical properties. HIFα and HIFγ consist of three protein domains (N-termini, C-termini, and central rod domain). To begin to understand the structure-function relationship between the protein domains in fiber formation and properties in a synthetic fiber spinning system, we designed recombinant protein constructs with varying combinations of the N-terminus, central rod domain (CRD), and C-terminus for both the α and γ proteins. The constructs, for both α and γ, were expressed, purified, and spun into dry fibers, which were then tested and analyzed for mechanical and structural properties. Mechanical testing revealed that the α constructs had the highest tensile strength when both termini were removed while including either terminus improved strain and toughness compared to α CRD constructs. The γ constructs displayed improved tensile strength and elastic modulus when only the N-terminus was present. Mixing the α and γ constructs generally enhanced the mechanical properties compared to the full-length rHIFα and rHIFγ. Fourier transform infrared-attenuated total reflection (FTIR-ATR) analysis indicated that the CRD contributes more to the β-sheet content in the stretched fibers, while the termini contribute more to the α-helical/random coil regions. These findings provide valuable insights into the roles of the different protein domains in the assembly and mechanical performance of rHIF and other recombinantly expressed IF. By understanding these structure-function relationships, functionally tailored recombinant IF proteins can be designed for specific applications in biomaterials developments.

Fast spectroscopic and multisensor methods for analysis of glucosamine and hyaluronic acid in dietary supplements

There is a lack of fast and inexpensive analytical methods for quantification of key ingredients in dietary supplements. Here we explore the potential of near infrared (NIR) spectrometry, attenuated total reflection infrared (ATR-IR) spectrometry and potentiometric multisensor system (MSS) in quantitative determination of glucosamine and hyaluronic acid in commercial samples of dietary supplements. All three methods have demonstrated their applicability for this task when combined with chemometric data processing. Principal Component Analysis (PCA) revealed similarities across the three techniques, indicating the presence of distinct sample composition. Partial least squares (PLS) models were constructed for glucosamine and hyaluronic acid quantification. The root mean square error of cross validation (RMSECV) for glucosamine quantification varied between 7.7 wt% and 8.9 wt%. NIR spectrometry has demonstrated the best accuracy for hyaluronic acid (RMSECV = 9.9 wt%), while ATR-IR and MSS yielded somewhat worse performance with RMSECV values of 12.1 and 11.3 wt%, respectively. The findings of this study indicated that NIR, ATR-IR and MSS exhibit reduced accuracy in comparison to complex and high-precision analytical techniques. However, they can be employed for the rapid, semi-quantitative evaluation of glucosamine and hyaluronic acid in dietary supplements, with the possibility of integration into routine quality control procedures.

Infrared biospectroscopy as a rapid screening tool for COVID-19 diagnosis

BackgroundAdvanced screening technologies, particularly biospectroscopic techniques like infrared attenuated total reflection (IR-ATR) spectroscopy, are gaining significance for their potential to offer fast, reliable, and specific diagnostic methods. These techniques, combined with chemometric approaches, have been increasingly applied for identifying bacterial and viral infections, cancer screening, and are now reported as useful in the context of COVID-19 and Long-COVID. The application IR-ATR, in point-of-care settings is crucial across various contexts. The ongoing progress in deploying IR-ATR in clinical settings represents a significant advancement in infectious disease screening.ObjectiveThe main objective of this study is to demonstrate the efficacy of IR-ATR as a rapid, sensitive, and specific tool for pathogen detection and infection monitoring at the clinical level, in agreement with existing literature.MethodsThe present study applied IR-ATR spectroscopy as a direct screening methodology that discriminates between patients infected with the SARS-CoV-2 virus and healthy subjects via dried serum samples.ResultsThe chemometric analysis through PCA presented an accuracy of 99.18% with a sensitivity and specificity of 98.83% and 97.32% respectively.ConclusionsThis approach supports the potential of IR-ATR for pathogen detection -SARS-CoV-2- in clinical settings as a rapid, sensitive, specific and minimally invasive technique that could be valuable for the deployment of rapid platforms for pathogen identification and viral infection monitoring.

Rapid Screening of Methane-Reducing Compounds for Deployment in Livestock Drinking Water Using In Vitro and FTIR-ATR Analyses

Several additives have been shown to reduce enteric methane emissions from ruminants when supplied in feed. However, utilising this method to deliver such methane-reducing compounds (MRCs) in extensive grazing systems is challenging. Use of livestock drinking water presents a novel method to deliver MRCs to animals in those systems. This work evaluated 13 MRCs for suitability to be deployed in this manner. Compounds were analysed for solubility and stability in aqueous solution using Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. Furthermore, aqueous solutions of MRCs were subjected to variations in temperature and starting pH of water used to assess solubility and stability of the MRCs in simulated water trough conditions, also using FTIR-ATR spectroscopy. In vitro batch culture fermentations were carried out using a medium-quality tropical grass feed substrate, to simulate pastures consumed by cattle in extensive grazing systems. Measurements were made of total gas and methane production, in vitro dry matter digestibility (IVDMD), and volatile fatty acid (VFA) concentration. Of the MRCs tested, 12 were found to be soluble and stable in water using the FTIR method employed, whilst the other could not be measured. Of the 12 soluble and stable MRCs, one containing synthetic tribromomethane (Rumin8 Investigational Veterinary Product) reduced methane production by 99% (p = 0.001) when delivered aqueously in vitro, without a reduction in IVDMD (p = 0.751), with a shift towards decreased acetate and increased propionate production and decreased total VFA production (p < 0.001). Other compounds investigated also appeared suitable, and the methods developed in this study could be used to guide future research in the area.

Plant Factory Speed Breeding Significantly Shortens Rice Generation Time and Enhances Metabolic Diversity

Rice (Oryza sativa L.) plays a pivotal role in global food security, yet its breeding is constrained by its long generation time and seasonality. To enhance rice breeding efficiency and meet future food demands, we have developed a vertical hydroponic breeding system integrated with light-emitting diodes (LEDs) lighting in a closed plant factory (PF), which significantly accelerates rice growth and generation advancement. The results show that indica rice can be harvested as early as after 63 days of cultivation, a 50% reduction compared with field cultivation, enabling the annual harvesting of 5–6 generations within the PF. A hyperspectral imaging system (HSI) and attenuated total reflectance infrared (ATR-IR) spectroscopy were further employed to characterize the chemical composition of the PF- and field-cultivated rice. Metabolomics analysis with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) revealed that, compared with the field-cultivated rice, the PF-cultivated rice exhibited an up-regulation of total phenolic acids along with 68 non-volatile and 19 volatile metabolites, such as isovitexin, succinic acid, and methylillicinone F. Overall, this study reveals the unique metabolic profile of PF-cultivated rice and highlights the potential of PFs to accelerate the breeding of crops such as rice, offering an innovative agricultural strategy to support food security in the face of global population growth and climate change.

Mussel-inspired bifunctional coating for long-term stability of oral implants

Peri-implantitis and osseointegration failure present considerable challenges to the prolonged stability of oral implants. To address these issues, there is an escalating demand for a resilient implant surface coating that seamlessly integrates antimicrobial features to combat bacteria-induced peri‑implantitis, and osteogenic properties to promote bone formation. In the present study, a bio-inspired poly(amidoamine) dendrimer (DA-PAMAM-NH2) is synthesized by utilizing a mussel protein (DA) known for its strong adherence to various materials. Conjugating DA with PAMAM-NH2, inherently endowed with antibacterial and osteogenic properties, results in a robust and multifunctional coating. Robust adhesion between DA-PAMAM-NH2 and the titanium alloy surface is identified using confocal laser scanning microscopy (CLSM) and attenuated total reflectance-infrared (ATR-IR) spectroscopy. Following a four-week immersion of the coated titanium alloy surface in simulated body fluid (SBF), the antimicrobial activity and superior osteogenesis of the DA-PAMAM-NH2-coated surface remain stable. In contrast, the bifunctional effects of the PAMAM-NH2-coated surface diminish after the same immersion period. In vivo animal experiments validate the enduring antimicrobial and osteogenic properties of DA-PAMAM-NH2-coated titanium alloy implants, significantly enhancing the long-term stability of the implants. This innovative coating holds promise for addressing the multifaceted challenges associated with peri‑implantitis and osseointegration failure in titanium-based implants. Statement of significanceProlonged stability of oral implants remains a clinically-significant challenge. Peri-implantitis and osseointegration failure are two important contributors to the poor stability of oral implants. The present study developed a mussel-bioinspired poly(amidoamine) dendrimer (DA-PAMAM-NH2) for a resilient implant surface coating that seamlessly integrates antimicrobial features to combat bacteria-induced peri‑implantitis, and osteogenic properties to promote bone formation to extend the longevity of oral implants.

Isolation and Electronic Structures of Lanthanide(II) Bis(trimethylsilyl)phosphide Complexes.

While lanthanide (Ln) silylamide chemistry is mature, the corresponding silylphosphide chemistry is underdeveloped, with [Sm{P(SiMe3)2}{μ-P(SiMe3)2}3Sm(THF)3] being the sole example of a structurally authenticated Ln(II) silylphosphide complex. Here, we expand the Ln(II) {P(SiMe3)2} chemistry through the synthesis and characterization of nine complexes. The dinuclear "ate" salt-occluded complexes [{Ln[P(SiMe3)2]3(THF)}2(μ-I)K3(THF)] (1-Ln; Ln = Sm, Eu) and polymeric "ate" complex [KYb{P(SiMe3)2}3{μ-K[P(SiMe3)2]}2]∞ (2-Yb) were prepared by the respective salt metathesis reactions of parent [LnI2(THF)2] (Ln = Sm, Eu, Yb) with 2 or 3 equiv of K{P(SiMe3)2} in diethyl ether. The separate treatment of these complexes with either pyridine or 18-crown-6 led to the formation of the mononuclear solvated adducts trans-[Ln{P(SiMe3)2}2(py)4] (3-Ln; Ln = Sm, Eu, Yb) and [Ln{P(SiMe3)2}2(18-crown-6)] (4-Ln; Ln = Sm, Eu, Yb), with concomitant loss of K{P(SiMe3)2}. The complexes were characterized by a combination of NMR, electron paramagnetic resonance (EPR), attenuated total reflectance infrared (ATR-IR), electronic absorption and emission spectroscopies, elemental analysis, SQUID magnetometry, and single crystal X-ray diffraction. We find that these complexes contrast with those of related Ln(II) bis(silyl)amide complexes due to differences in ligand donor atom hardness and ligand steric requirements from Ln-P bonds being longer than Ln-N bonds. This leads to higher coordination numbers, shorter luminescence lifetimes, and smaller easy-axis magnetic anisotropy parameters.

Early and swift identification of fungal-infection using infrared spectroscopy

Fungal pathogens pose significant threats to agricultural crops and food products, leading to economic losses, compromised food quality, and health hazards. Early detection is crucial for effective control and treatment. This study explores Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy for rapid fungal detection in bread. Using a machine learning algorithm (Random Forest), FTIR-ATR accurately distinguished between pure and infected bread samples, achieving 86% overall accuracy and 84% accuracy in identifying specific fungi like Rhizopus and Aspergillus on the first day of infection. These findings highlight FTIR-ATR’s potential for early fungal infection detection, promising improved food quality and reduced economic losses through timely intervention.

Antibody-Based Array for Tacrolimus Immunosuppressant Monitoring with Planar Plastic Waveguides Activated with an Aminodextran-Lipase Conjugate.

Cyclic olefin copolymers (COC; e.g., Zeonor, Topas, Arton, etc.) are materials with outstanding properties for developing point-of-care systems; however, the lack of functional groups in their native form makes their application challenging. This work evaluates different strategies to functionalize commercially available Zeonor substrates, including oxygen plasma treatment, photochemical grafting, and direct surface amination using an amino dextran-lipase conjugate (ADLC). The modified surfaces were characterized by contact angle measurements, Fourier transform infrared-attenuated total reflection analysis, and fluorescence assays based on evanescent wave excitation. The bioaffinity activation through the ADLC approach results in a fast, simple, and reproducible approach that can be used further to conjugate carboxylated small molecules (e.g., haptens). The usefulness of this approach has been demonstrated by the development of a heterogeneous fluorescence immunoassay to detect tacrolimus (FK506) immunosuppressant drug using an array biosensor platform based on evanescence wave laser excitation and Zeonor-ADLC substrates. Surface modification with ADLC-bearing FK506 provides a 3D layer that efficiently leads to a remarkably low limit of detection (0.02 ng/mL) and IC50 (0.9 ng/mL) together with a wide dynamic range (0.07-11.3 ng/mL).

A novel intralamellar semi‐bioresorbable keratoprosthesis—Part B: Surface functionalization and physico‐chemical characterization toward site‐specific cellular activity

AbstractIn this article, site‐specific functionalized keratoprosthesis (KPro) was accomplished to meet epithelial on‐growth on the anterior optical surface, inhibit cell adhesion on the posterior optic surface, and promote cell ingrowth at the peripheral tissue‐haptic‐flange interface toward tissue integration. Gelatin immobilization on PC4 hydrogel surfaces was achieved through acid hydrolysis followed by EDC/NHS chemistry, and polyethylene glycol‐diacrylate (PEGDA)‐modified inter‐penetrating network (IPN) surfaces were prepared using photo‐polymerization of ethylene glycol‐diacrylate (EGDA) for enhancing and inhibiting cellular growth, respectively. The surface chemical structures of modified hydrogels were characterized using attenuated total reflectance‐infrared (ATR‐IR) spectroscopy and a bicinchoninic acid (BCA) protein adsorption assay. Further, suitable differentially functionalized surfaces were prepared and characterized using the universal testing machine (UTM), refractometer, atomic force microscopy (AFM), and contact angle measurements to understand mechanical, optical, surface morphological, and wettability properties, respectively. Finally, in vitro site‐specific cell adhesion, cell inhibition, and cell ingrowth functionalities were tested using isolated goat corneal limbal epithelial stem cells and corneal stromal fibroblast cells, respectively. Overall, the two connective articles represent a successful endeavor to develop a more esthetically pleasing, mechanically stable, tissue‐free hydrogel KPro with site‐specific surface functionality nearly mimicking the cornea's functionality. A further pre‐clinical investigation is necessary to advance this functional novel KPro to reality, especially the tissue integration aspect.

Ruminal CO2 Holdup Monitoring, Acidosis Might Be Caused by CO2 Poisoning

The ruminal buffering system is composed of bicarbonate (HCO3-) and dissolved CO2 (dCO2). While low pH indicates high dCO2 formation, the pH scale is a ratio between acids and bases in a solution, i.e. HCO3- and dCO2, and fail to provide individual component concentrations. For instance, modern feeding practices can reduce CO2 gas fugacity from the ruminal fluid or "CO2 holdup". Under those conditions, not only dCO2 can reach critical concentrations, but the buffering system might favour HCO3- formation resulting in normal ruminal pH values, the quotient, regardless of the harmful dCO2 accumulation. Consequently, subacute ruminal acidosis (SARA), traditionally associated with low or variable pH, might be triggered by CO2 holdup. This observational study aimed to continuously monitor ruminal dCO2 and characterised CO2 holdup within the ruminal fluid targeting the specific infrared signal of dCO2 with an attenuated total reflectance infrared (ATR-IR) spectrometer. Three lactating dairy cattle were longitudinally exposed to diets designed to elevate both ruminal dCO2 and SARA risk. Indwelling pH sensors and ruminal fluid samples served as references for dCO2 analysis, while a categorical analysis detected CO2 holdup from the output of the ATR-IR sensor. Milk yield, milk components, and feed intake supported the known positive role for high dCO2 in rumen function. However, SARA was associated with ruminal CO2 holdup, suggesting that prolonged exposure to critical dCO2 concentrations during extended postprandial periods might trigger SARA. Continuous dCO2 monitoring with the proposed methodology and analysis may offer a valuable tool for optimising rumen function and prevent SARA risk.

Corrosion Behavior of 3104 Aluminum Cans When Used as Packaging for Chinese Liquor.

Aluminum cans are commonly used for packaging soft drinks and low-alcohol beverages due to their good recyclability. To enhance the economic cycle and expand the packaging of liquors, the feasibility of commercial 3104 aluminum cans for packaging Chinese liquor was studied. The aluminum's migration into alcoholic solutions was studied using inductively coupled plasma emission spectroscopy (ICP-OES). Electrochemical impedance spectroscopy (EIS) was used to study the corrosion process of epoxy coatings on the aluminum cans. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), infrared attenuated total reflection (IR-ATR), and X-ray diffraction (XRD) were used to determine the inner coatings and adhering surfaces of the cans and the corrosion process. The results showed that the maximum aluminum migration in Chinese liquor was 4.3572 mg/kg at 60 °C for 30 days. The epoxy coating was corroded enough to decrease the coating impedance and expose the metal substrate after 25 days. Permeation and aging degradation of coatings are the main factors to consider when packaging liquor.

Ligand-Engineered Structural and Physiochemical Properties of 1D Molybdenum-MOFs: A Seldom Explored System for Photocatalytic Applications.

As one of the seldom explored systems, molybdenum-based metal-organic frameworks (Mo-MOFs) with different ligands such as terephthalic acid (Mo-TA), 2-aminoterephthalic acid (Mo-ATA), benzenetricarboxylic acid (Mo-BTC), 2-methylimidazole (Mo-2MI), 2-bipyridine (Mo-2bpy), and 4-bipyridine (Mo-4bpy) were developed in this study. X-ray diffraction (XRD), Raman, and attenuated total reflectance-infrared (ATR-IR) analyses confirmed the ligand-dependent crystal structure of the Mo-MOFs along with the characteristic functional groups present in the respective systems. Interestingly, the morphology of all of these the developed Mo-MOFs was found to be a one-dimensional rod-like structure, which was attributed to the binding nature of the ligands onto the growing Mo-frameworks. Optical analysis indicated that all these Mo-MOFs exhibit ultraviolet (UV) light absorption properties with band gap energy in the range of 3.47-3.03 eV. Among the various Mo-MOFs developed, Mo-4bpy MOF degraded a maximum of ∼76 and 62% of malachite green and Congo red dyes, respectively, under sunlight irradiation. The observed improved photocatalytic efficiency of Mo-4bpy MOF was attributed to its appropriate band edge potential, confirmed by Mott-Schottky analysis, improved carrier lifetime (∼34.6 ns) estimated using the time-resolved photoluminescence (TRPL) spectrum, presence of elements with stable oxidation states in the system confirmed by X-ray photoelectron spectroscopy (XPS), improved charge transfer characteristics, and decreased recombination resistance, as confirmed by impedance and PL analyses, respectively. The degradation of Mo-4bpy MOFs mediated by superoxide (•O2-) and hydroxyl radicals (OH•) was further confirmed by scavenger studies. Cyclic studies performed for up to 5 cycles suggested that the degradation efficiency of the Mo-4bpy MOF was stable, attributed to its excellent structural, optical, and morphological features confirmed via postcharacterization of the recycled photocatalyst.

Kraft lignin-based polyurethanes: Bulk properties, stability and adhesion to native aluminum surfaces

Lignin as a byproduct from pulp and paper manufacturing has been extensively investigated as raw material for polymer developments. Although, fundamental topics related to the adhesion mechanisms of lignin-based reactive polyurethanes (LPU) still remain unclear. In this work, LPU thin films on native aluminum surface were prepared and characterized. Diluted in THF, employed as the solvent, reactive mixtures of 4,4′-methylene diphenyl isocyanate (4,4′-MDI) and the soluble fraction of three lignins (liquid hydroxypropylated Kraft lignin and two powder Kraft lignins with different pH) were used for LPU thin film deposition via spin coating on aluminum (PVD layer on silicon wafer). The resulting film thickness ranged from 8 nm to several micrometers. The chemical state of the three LPU compositions was assessed in bulk by infrared attenuated total reflectance (IR-ATR) and in the thin films by infrared external reflection absorption spectroscopy (IR-ERAS). Binding energies of 4,4′-methylene diphenyl diisocyanate with aliphatic and aromatic hydroxyl groups were estimated using Density Functional Theory (DFT) simulations. Thus, besides the elucidation of the bulk chemical state of LPUs, the relation to adhesion and stability of LPUs to a native aluminum surface was evaluated. In addition, film topography and homogeneity were monitored by SFM. All lignin types form uniform and homogeneous films. Results revealed a higher consumption of isocyanate groups (NCO) in the formulation with the alkaline Kraft lignin than with the acid one, despite its lower hydroxyl content. A gradient of unreacted NCO was observed in LPU thin films obtained with the powder Kraft lignin types. Residual NCO is also found in thicker films, while the thinnest films did not contain unreacted NCO anymore, indicating the activating effect of the native aluminum surface on LPU formation.

Rapid Screening of Methane-Reducing Compounds for Deployment via Water with a Commercial Livestock Supplement Using In Vitro and FTIR-ATR Analyses

The addition of methane-reducing compounds (MRCs) to livestock drinking water presents an alternative method for enteric methane mitigation in extensive systems where these compounds cannot be fed through the diet. This work evaluated several such compounds with the potential to be deployed in this manner. Methane-reducing compounds were selected based on the existing literature and likelihood of dissolution when combined with a commercially available water-based nutrient supplement (uPRO) (uPRO ORANGE®, DIT AgTech, QLD, Australia). This, in turn, would demonstrate the capacity for MRCs to be administered through animal drinking water when such supplements are in use. This technique requires the analysis of MRC solubility and stability in solution, which was completed via Fourier transform infrared-attenuated total reflectance spectroscopy. The uPRO supplement is comprised of urea, urea phosphate, and ammonium sulfate, providing nitrogen, phosphorus, and sulfur—limiting nutrients for ruminants grazing extensive systems during drier periods of the year. Accordingly, medium-quality Rhodes grass hay was used in fermentation runs to simulate a basal diet during the dry season. Methane-reducing compounds were assessed in accordance with each variable measured (gas/methane production, dry matter digestibility, stability under different environmental conditions) along with existing research in the field to determine the most suitable compound for co-administration. Whilst most compounds examined in this study appeared to retain their structure in solution with uPRO, fermentation results varied in terms of successful methane mitigation. The additive Agolin Ruminant L emerged as the most promising compound for further in vivo investigation.

Combined bulk nanostructuring and surface modifications of titanium substrate for improved corrosion behavior

Titanium has proven to be a game-changing biomaterial in biomedical engineering. Titanium and its alloys offer superior properties such as machinability, mechanical strength, biocompatibility, and corrosion resistance, making them indispensable for safer and more efficient biomedical treatments. While commercially pure titanium (Cp-Ti) is an exceptional material for medical applications, it has some limitations. Allergic reactions can manifest as localized inflammation around the implant, and corrosion compromises implant stability. Corrosion starts with cracking from the surface and disrupts the protective passive oxide layer when touching body fluids, and failure occurs. This study utilized a combination of techniques including grain refinement of Cp-Ti via equal channel angular pressing (ECAP), two-step anodization (for creating titanium oxide nanotubes coatings), annealing at 450°C and 570°C, and immersion in simulated body fluid (SBF) to create a Hydroxyapatite (HA) film coating. These methods addressed various challenges and provided a positive approach to improving corrosion behavior. The microstructure of Nano-Ti was evaluated by Transmission Electron Microscopy (TEM). The morphology of the as-anodized samples and corroded areas were investigated using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The crystalline phases of titanium nanotubes (TNTs) were evaluated through X-ray diffraction (XRD). The presence of hydroxyapatite particles was analyzed and characterized by FESEM coupled with Energy Dispersive Spectroscopy (EDS) and Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR). The corrosion behavior was evaluated using a potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). Results indicated that grain refinement and successive surface modifications significantly impact corrosion performance. The nanostructured (Nano-Ti) sample, after the final modification stage, exhibited an approximately 11-fold decrease in corrosion rate and over a 450-fold rise in polarization resistance (7.4 MΩ) compared to as-anodized Cp-Ti sample and a 7-fold increase in its Cp-Ti counterpart, and showed excellent adhesion strength compared to other samples.