Nuclear Spectroscopy Research Articles

First Stability Characterization for a CZT Detection System in an e+e− Collider Environment

The SIDDHARTA-2 collaboration has developed a novel X-ray detection system based on cadmium-zinc-telluride (CZT, CdZnTe), marking the first application of this technology at the DAΦNE electron-positron collider at INFN-LNF. This work aims to demonstrate the stability of the detectors’ performance in terms of linearity and resolution over short and long periods, thereby establishing their suitability for precise spectroscopic measurements within a collider environment. A reference calibration spectrum is presented in association with findings from assessments of linearity and resolution stability. Additionally, this study introduces a validated model of the response function of the detector. The relative deviations from the nominal values for the source transitions, obtained by fitting the entire spectrum with a background function and the previously introduced response function, are reported. Finally, a comparison of the calibration performance with and without beams circulating in the collider’s rings is presented. These promising results pave the way for applying CZT detectors in kaonic atom studies and, more generally, in particle and nuclear physics spectroscopy.

Synthesis, characterization, theoretical, and evaluation of eco-friendly phenytoin-based corrosion inhibitors for mild steel

This study explores the corrosion inhibition potential of two newly synthesized phenytoin-based compounds, (E)-2-(2-(2-chlorobenzylidene)hydrazineyl)-5,5-diphenyl-3,5-dihydro-4H-imidazol-4-one (2-ClPh-DDI) and (E)-2-(2-(2,4-dichlorobenzylidene)hydrazineyl)-5,5-diphenyl-3,5-dihydro-4H-imidazol-4-one (2,4-diClPh-DDI), in 1 M HCl solution. Both compounds exhibited remarkable inhibition efficiencies, reaching 97.7 % and 98.6 %, respectively. Comprehensive structural characterization was conducted using fourier-transform infrared spectroscopy, nuclear magnetic spectroscopy, and high-resolution mass spectrometry, both inhibitors demonstrated high purity and stability. Theoretical evaluations, including Monte Carlo simulation and density functional theory calculations, confirmed high reactivity and strong inhibition capabilities. Electrochemical measurements demonstrated a concentration-dependent inhibition effect, sustained up to 328 K. Adsorption isotherms revealed that these inhibitors effectively displace water molecules, forming a robust adsorbed layer that protects the mild steel surface. Surface analysis using microscopy confirmed the formation of protective layers and the presence of iron-inhibitor complexes, highlighting the compounds’ effectiveness in mitigating corrosion. The combined experimental and theoretical insights underscore the promising role of these phenytoin derivatives as eco-friendly corrosion inhibitors for mild steel.

Role of chirality in photoinduced electron transfer in pentapeptide (L)-His-(L/D)-Asp-(L/D)-Ser-Gly-(L)Tyr in solutions

Factors governing electron transfer (ET) in proteins and peptides are widely studied due to the role of ET in biologically important processes. One of them is the influence of the optical configuration of amino acids on the ability of peptides to aggregate into ensembles: dimers, oligomers, fibrils. Such assemblies, called amyloids, are known to contain D-isomers of asparagine and serine, and their presence in aging living organisms leads to a number of diseases, including Alzheimer’s disease. However, how these amino acids affect the structure and properties of peptides have not yet been established. Using the example of the pentapeptide (PP)-(L)histidine-(L)asparagine-(L)serine-glycine-(L)tyrosine and its analogues with D-asparagine and D-serine, this article studies the comparative reactivity of optical isomers in photoinduced ET using chemically induced dynamic nuclear polarization (CIDNP), fluorescence spectroscopy and quantum chemical calculations. The CIDNP method was chosen because it had previously demonstrated high sensitivity to ET processes in chiral dyads linked by non-covalent interactions. ET involving Tyr and His residues of PP was detected under UV irradiation both in the presence of an electron acceptor, naproxen, and during photolysis of PP itself. It was shown that the efficiency of ET and PP fluorescence quenching differ for optical isomers of asparagine and serine. In addition, the dependence of the CIDNP efficiency on the PP concentration showed that ET between Tyr and peptide bonds can occur in the dimer of the PP. Quantum chemical calculation confirm the possibility of PP self-association.

Interrogating stonefish venom: small molecules present in envenomation caused by Synanceia spp.

The stonefish Synanceia verrucosa and Synanceia horrida are arguably the most venomous fish species on earth and the culprits of severe stings in humans globally. Investigation into the venoms of these two species has mainly focused on protein composition, in an attempt to identify the most medically relevant proteins, such as the lethal verrucotoxin and stonustoxin components. This study, however, focused on medically relevant small molecules, and through nuclear magnetic resonance, mass spectroscopy, and fractionation techniques, we discovered and identified the presence of three molecules new to stonefish venom, namely γ-aminobutyric acid (GABA), choline and 0-acetylcholine, and provide the first report of GABA identified in a fish venom. Analysis of the crude venoms on human nicotinic acetylcholine receptors (nAChRs) and a GABAA receptor (GABAAR) showed S. horrida venom could activate neuronal (α7) and adult muscle-type (α1β1δε) nAChRs, while both crude S. horrida and S. verrucosa venoms activated the GABAAR (α1β2γ2). Cytotoxicity studies in immunologically relevant cells (human PBMCs) indicated the venoms possess cell-specific cytotoxicity and analysis of the venom fractions on Na+ channel subtypes involved in pain showed no activity. This work highlights the need to further investigate the small molecules found in venoms to help understand the mechanistic pathways of clinical symptoms for improved treatment of sting victims, in addition to the discovery of potential drug leads.

Comparative Analysis of Bare and Quercetin-Loaded Nonionic Block Copolymer Micelles in an Artificial Gastrointestinal Medium.

Block copolymer micelles have been increasingly used for the solubilization and delivery of hydrophobic drugs. There exists a possibility of dissociation of micelles and formation of other association structures in contact with the gastrointestinal fluid. In this study, we demonstrated the effect of the fed-state intestinal fluid (FeSSIF) upon characteristics of bare and quercetin (QCT)-loaded pluronic 123 (P123) micelles. Characterizations were performed using dynamic light scattering (DLS), 1H NMR, heteronuclear single-quantum coherence (HSQC), two-dimensional 1H-1H nuclear Overhauser effect spectroscopy (2D-NOESY), and diffusion-ordered spectroscopy (DOSY). In the case of bare micelles, we found copolymer-bile salt mixed aggregates without any noticeable change in size. DOSY data revealed that lecithin formed a separate aggregate in the FeSSIF. Complete micellar solubilization of QCT could be verified by the disappearance of its proton signals. At higher dose levels, the diffusion coefficient of micelles increased in the FeSSIF. We speculate that QCT-induced hydrophobicity and availability of FeSSIF components would have driven the formation of small-sized mixed assemblies. On the contrary, the diffusion coefficient of micelles decreased with an increase in the QCT load in the medium devoid of FeSSIF components. We deduce that lack of lecithin and bile salts precluded the formation of mixed assemblies in this case, and therefore, micelles turned heavier at higher QCT loads. Such insights on self-assembled formulations can be valuable in improving their biological performance.

A high-molecular-weight flame retardant derived from bis[tetrakis(hydroxymethyl)phosphonium] sulfate for cotton fabrics

A high-molecular-weight flame retardant, bis[tetrakis(hydroxymethyl)phosphonium] (THPS)-urean-(PO3)(NH4)2, was synthesized for cotton fabrics. Fourier-transform infrared spectroscopy, nuclear magnetic spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy analyses confirmed that (THPS-urea)n-(PO3)(NH4)2 effectively infiltrated the fibers and grafted onto cellulose through N–P(=O)–O–C covalent bonds. The fabric treated with 30 wt% of (THPS-urea)n-(PO3)(NH4)2 (C30) had a limiting oxygen index of 46.8 %. Even after 50 laundering cycles according to the AATCC 61-2013 3A standard, C30 maintained a limiting oxygen index of 39.8 %. Thermogravimetric-Fourier-transform infrared spectrometry, thermogravimetry, and cone calorimetry tests revealed that C30 exhibited excellent flame retardancy. Upon exposure to flame, C30 formed a stable char layer, which prevented the spread of heat and combustible gases. Additionally, C30 was free of formaldehyde, making it suitable for producing infant textiles. After grafting with the flame retardant, C30 retained its mechanical properties. The high-molecular-weight flame retardant enhanced the flame resistance and durability of cotton materials owing to its numerous N–P(=O) (ONH4)2 groups, which facilitated a condensed-phase flame retardancy mechanism.

Structural characterization and physicochemical properties of different hydrophilic natural deep eutectic solvents.

To overcome the toxic nature of organic solvents, scientific interest in the use of green solvents, particularly natural deep eutectic solvents (NADES), has increased over the past decade, leading to new applications in the food, nutraceutical, pharmaceutical, and cosmetic industries. Understanding the physicochemical properties and molecular interactions of NADES is essential for uncovering new potential applications in these fields. In this study, several lactic and citric acid-based NADES, as well as chloride choline- and urea-based NADES, were evaluated for their physicochemical properties, including density, pH, viscosity, conductivity, and refractive index. Additionally, nuclear magnetic resonance (NMR), and in particular nuclear Overhauser enhancement spectroscopy (NOESY), was employed to investigate the intermolecular interactions between the NADES components to confirm the formation of the eutectic mixture. The extraction efficiency of the confirmed NADES was tested for extracting polyphenols as a proof of concept to highlight their relationship with the measured properties. Lactic and choline chloride-based NADES provided the highest extraction yields. These results were also compared with the predicted extraction capabilities of each NADES provided by the COSMO-RS software.

Homonukleare Super‐Resolution NMR‐Spektroskopie

AbstractIn homonuklearen 1H NMR ‐Spektren wie dem [1H,1H]‐NOESY‐Spektrum (Nuclear Overhauser Enhancement Spectroscopy), einem historischen Eckpfeiler der biomolekularen NMR‐Strukturbiologie, treten innerhalb eines Quadrats von etwa 100 ppm2 hunderte bis tausende von Kreuzpeaks auf, was zu einer starken Signalüberlappung führt. Die spektrale Auflösung ist daher ein limitierender Faktor für die eindeutige Zuordnung der chemischen Verschiebung und die Interpretation der Daten für die Dynamik und Strukturaufklärung. Die Aufnahme der Spektren bei höheren Magnetfeldern, z. B. bei einer 1.2 GHz 1H‐Frequenz, hilft, die spektrale Überlagerung zu verringern, da die Auflösung proportional zur Magnetfeldstärke skaliert. Hier zeigen wir, dass die Linienbreiten von Kreuzpeaks in [1H,1H]‐NOESY‐ und [1H,1H]‐TOCSY‐Spektren durch Super‐Resolution Spektroskopie in jeder Dimension um einen Faktor 2 bis 3 weiter reduziert werden können. In der indirekten Dimension wird eine zusammengesetzte, exponentiell‐kosinus‐gewichtete Anzahl von Scans entlang der Zeitinkremente gemessen und durch eine Windowfunction digital geglättet, während in der direkten Dimension ein Produkt aus Exponential‐ und Kosinusfunktion alsApodisierungsfunktion angewendet wird. Darüber hinaus wird eine Zeitersparnis bei der Messung durch Reduced‐Acquired Super‐ Resolution (RASR) eingeführt. Die Anwendung auf das 20 kDa Protein KRAS zeigt, dass hochaufgelöste NMR‐Spektren, die sich für eine automatisierte Analyse eignen, in weniger als 3 Stunden aufgenommen werden können. Die Methode eröffnet einen Weg zur automatisierten Zuordnung chemischer Verschiebungen, Dynamik und Strukturbestimmung von unmarkierten kleinen und mittelgroßen Proteinen innerhalb von 24 Stunden.

Deciphering the Influence of Zwitterionic Surfactants on Pluronic Co-assemblies: A Synergistic Odyssey through Spectroscopic, Microscopic, and Scattering Techniques.

Fundamental investigations into the photophysical properties and microenvironmental features of pluronic-zwitterionic surfactant mixed assemblies are essential for advancing our understanding of molecular interactions at the nanoscale, setting the stage for innovative solutions in drug delivery, diagnostics, and other applications of pluronic-zwitterionic surfactant assemblies. This investigation explores the intricate photophysics of pluronic-zwitterionic surfactant mixed assemblies, utilizing the twisted intramolecular charge transfer state forming styryl dye trans-2-[(4-dimethylamino) styryl] benzothiazole as a probe. By comparing the behaviors of two distinct poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) block copolymers with block composition of (PEO)132-(PPO)50-(PEO)132 [F108] and (PEO)100-(PPO)65-(PEO)100 [F127] at concentrations of 5 and 10 wt %, this study systematically examines the impact of the addition of zwitterionic surfactants. Through a comprehensive set of analytical techniques, including UV-visible absorption, steady-state emission, and time-resolved fluorescence emission studies, significant alterations in the emission spectra and quantum yields were observed upon the addition of zwitterionic surfactants. These modifications suggest a dynamic equilibrium for the transitioning of dye molecules between various microenvironments within the assemblies. Additionally, dynamic light scattering, zeta potential (ζ), nuclear Overhauser effect spectroscopy, small-angle neutron scattering, cryogenic transmission electron microscopy, field emission scanning electron microscopy, and fluorescence lifetime imaging microscopy analyses have shed light on the substantial impact of surfactant incorporation on the structural properties of assemblies.

Phytochemical Analysis and Biological Evaluation of Carob Leaf (Ceratonia siliqua L.) Crude Extracts Using NMR and Mass Spectroscopic Techniques.

Carob leaves have gained attention for their bioactive properties and traditional medicinal uses, including as treatment for diabetes, digestive disorders, and microbial infections. The aim of this study was to explore the phytochemical composition of carob leaf acetone extracts using advanced spectroscopic techniques. The combined use of heteronuclear nuclear magnetic resonance (NMR) experiments with 1D selective nuclear Overhauser effect spectroscopy (NOESY) offers detailed structural insights and enables the direct identification and quantification of key bioactive constituents in carob leaf extract. In particular, the NMR and mass spectrometry techniques revealed the presence of myricitrin as a predominant flavonoid, as well as a variety of glycosylated derivatives of myricetin and quercetin, in acetone extract. Furthermore, siliquapyranone and related gallotannins are essential constituents of the extract. The potent inhibitory effects of the carob leaf extract on Staphylococcus aureus (MIC = 50 μg mL-1) and a-glucosidase enzyme (IC50 = 67.5 ± 2.4 μg mL-1) were also evaluated. Finally, the antibacterial potency of carob leaf constituents were calculated in silico; digalloyl-parasorboside and gallic acid 4-O-glucoside exert a stronger bactericidal activity than the well-known myricitrin and related flavonoids. In summary, our findings provide valuable insights into the bioactive composition and health-promoting properties of carob leaves and highlight their potential for pharmaceutical and nutraceutical applications.

Homonuclear Super-Resolution NMR Spectroscopy.

In homonuclear 1H NMR (nuclear magnetic resonance) spectra such as [1H,1H]-NOESY (Nuclear Overhauser Enhancement spectroscopy), which is a historic cornerstone spectrum for biomolecular NMR structural biology, hundreds to thousands of cross peaks are present within a square of approximately 100 ppm2 leading to a lot of signal overlap. Spectral resolution is thus a limiting factor for unambiguous chemical shift assignment and data interpretation for dynamics and structure elucidation. Acquiring the spectra at higher magnetic fields such as at a 1.2 GHz 1H frequency helps to reduce spectral crowding, since resolution scales proportionally to the magnetic field strength. Here, we show that the linewidths of cross peaks in [1H,1H]-NOESY and [1H,1H]-TOCSY spectra can be further reduced by a factor of 2-3 in each dimension by super-resolution spectroscopy. In the indirect dimension a composite exponential-cosine weighted number of scans along the time increments are recorded and digitally smoothened by a window function, while in the direct dimension an exponential-cosine window function is applied. Furthermore, measurement time saving by reduced-acquisition super-resolution (RASR) is introduced. Application to the 20 kDa protein KRAS shows that highly resolved NMR spectra suitable for automated analysis can be acquired within less than 3 hours. The method opens an avenue towards automated chemical shift assignment, dynamics and structure determination of unlabeled small and medium size proteins within 24 hours.

Simple power-efficient preamplifier-shaper channel for readout interface of silicon detectors

This paper presents the design and characteristics of a front-end readout system for silicon sensors used in nuclear spectroscopy studies. Furthermore, the study proposes circuit topologies that combine gain-boosting and class-AB techniques featuring a good performance regarding gain, accuracy, speed, linearity, and power consumption, meeting the stringent requirements of deep submicrometer CMOS technologies. The readout channel comprises a charge-sensitive amplifier with a tunable discharge time, pole-zero cancellation circuit, and first-order unipolar shaper with a peaking time of 90 ns. The building blocks are made up of single-stage op-amps, thus not requiring compensation. Furthermore, the circuit is optimized for a detector capacitance of 5 pF, and the noise performance is discussed. Experimental results in a 180 nm CMOS process and a supply voltage of ±0.9 V validate the designed front-end channel. The total area of the chip obtained was 0.028 mm2. The conversion gain was 3.1 mV/fC, and the system maintained linearity up to an input charge range of 150 fC with a maximum output swing of 460 mV and recovered to the baseline within 400 ns. The compact design and the power consumption of only 1.97 mW provided a feasible solution for current radiation detectors coupled to many highly dense electronic channels.

Regulation of Microlocalization of Antioxidants by Surfactant Micelles in Oil-in-Water Emulsions.

The mass transport effect of aqueous micelles on antioxidants and oxidation products in emulsions may alter the rate, degree, and pathway of lipid oxidation. In this study, the dynamic mass transport of oxidation products and endogenous tocopherol during storage at different micelle concentrations was monitored by UV-vis spectrophotometry and high-performance liquid chromatography. Furthermore, the microlocalization of tocopherol in micelles was investigated using 1H nuclear magnetic resonance and nuclear Overhauser effect spectroscopy, fluorescence measurements, and molecular dynamics simulation. It was demonstrated that high-concentration micelles enhanced the emulsion stability by promoting the mass transport of hydroperoxides and endogenous antioxidants. The enhancement of micelles was a superposition effect of concentration, interaction sites, and binding force between tocopherols and Tween 20 molecules. Tween 20 concentration-induced favorable changes of microlocalization of tocopherol and dynamic mass transport demonstrated a new integrated perspective to control lipid oxidation.

Quantitative estimation and validation of Alectinib hydrochloride drug substance using quantitative nuclear magnetic resonance spectroscopy

Nuclear magnetic resonance spectroscopy has been recently used for quantitative estimation of drug substance which has numerous merits in pharmaceutical applications when compared to traditional methods of chromatography. Present study focuses on method development and validation of quantitative proton nuclear magnetic spectroscopy method for estimation of alectinib hydrochloride drug substance. This method involves use of internal standard in presence of alectinib hydrochloride. For quantitation, 1H NMR signals at 8.4 ppm and 6.7 ppm corresponding to analyte proton of alectinib and ethyl 4-(dimethyl amino) benzoate internal standard respectively were used. Moreover, this method was validated as per ICH guidelines for accuracy, precision, linearity, limit of detection, limit of quantitation, range and robustness. Assay estimation by Q-NMR is facile and time-efficient which does not require reference standard of analyte and yet accurate and precise alternative as compared to estimation by other chromatographic techniques.

Metabolomics-Based Machine Learning for Predicting Mortality: Unveiling Multisystem Impacts on Health.

Reliable predictors of long-term all-cause mortality are needed for middle-aged and older populations. Previous metabolomics mortality studies have limitations: a low number of participants and metabolites measured, measurements mainly using nuclear magnetic spectroscopy, and the use only of conventional statistical methods. To overcome these challenges, we applied liquid chromatography-tandem mass spectrometry and measured >1000 metabolites in the METSIM study including 10,197 men. We applied the machine learning approach together with conventional statistical methods to identify metabolites associated with all-cause mortality. The three independent machine learning methods (logistic regression, XGBoost, and Welch's t-test) identified 32 metabolites having the most impactful associations with all-cause mortality (25 increasing and 7 decreasing the risk). From these metabolites, 20 were novel and encompassed various metabolic pathways, impacting the cardiovascular, renal, respiratory, endocrine, and central nervous systems. In the Cox regression analyses (hazard ratios and their 95% confidence intervals), clinical and laboratory risk factors increased the risk of all-cause mortality by 1.76 (1.60-1.94), the 25 metabolites by 1.89 (1.68-2.12), and clinical and laboratory risk factors combined with the 25 metabolites by 2.00 (1.81-2.22). In our study, the main causes of death were cancers (28%) and cardiovascular diseases (25%). We did not identify any metabolites associated with cancer but found 13 metabolites associated with an increased risk of cardiovascular diseases. Our study reports several novel metabolites associated with an increased risk of mortality and shows that these 25 metabolites improved the prediction of all-cause mortality beyond and above clinical and laboratory measurements.

Lignin‐based nitrogen and phosphorus‐containing polylactic acid with flame‐retardant performances

AbstractPolylactic acid (PLA) is a new type of biodegradable material that has been applied in many fields such as extrusion, injection molding, film drawing, and spinning. In contrary, it does not have flame retardancy. In this paper, N‐PCDL was synthesized by amidation reaction between COOH of PCDL and NH2 of tetraethylenepentamine (TEPA), followed by an Atherton‐Todd reaction of unreacted NH2 at the other end of TEPA with PH of DOPO to prepare a novel lignin‐based flame retardant containing nitrogen and phosphorus (NP‐PCDL). The Fourier transform infrared spectroscopy (FT‐IR) and nuclear magnetic hydrogen spectroscopy (1H NMR) analysis results showed that proton peaks of CONH, PN, and NH appeared in the NP‐PCDL spectrum, while the characteristic absorption peak of PH bond disappeared in DOPO, the X‐ray photoelectron spectroscopy (XPS) results showed that the degraded lignin consisted of elements C and O, while NP‐PCDL consisted of elements C, O, N and P. The above results indicated that NP‐PCDL was successfully prepared. NP‐PCDL accounted for 3% (mass percentage, the same below), 5% and 10% of PLA, then lignin based flame‐retardant PLA composites were prepared by internal mixing and injection molding. Thermogravimetric analysis (TGA) showed that the residual carbon of PLA/3% NP‐PCDL, PLA/5% NP‐PCDL and PLA/10% NP‐PCDL at 800°C were higher than that of pure PLA, with the increase of 56.56%, 97.54%, and 301.64%, respectively; The analysis of SEM, XPS, and Raman showed that PLA/NP‐PCDL formed dense, regular and highly graphitized residual carbon with phosphorus nitrogen structure during the combustion process. At the same time, NH3, H2O and PO˙ free radicals were released, which could dilute combustible gases, destroy free radical chain reaction, isolate combustible gases and heat, so as to play a flame‐retardant role.

Observation of dynamic nuclear polarization echoes.

It is demonstrated that the time evolution of the electron-nuclear polarization transfer process during pulsed dynamic nuclear polarization (DNP) can be reversed on a microsecond timescale, leading to the observation of DNP echoes. The DNP echoes are induced by consecutive application of two pulse trains that produce effective Hamiltonians that differ only in the sign of the effective hyperfine coupling. The experiments have been performed on a frozen solution of trityl radicals in water/glycerol on a homebuilt X-band electron paramagnetic resonance/DNP spectrometer at 80 kelvins. We envisage that DNP echoes will play an important role in future development of pulsed DNP for sensitivity-enhanced nuclear magnetic resonance, hyperfine spectroscopy, and quantum sensing.

A novel and sustainable approach to efficiently modify cotton material via a physical flash-explosion with sub- or SCF-CO2 as medium

A novel and eco-friendly approach to modify natural cotton fiber by flash-explosion with a sub- or supercritical fluid of carbon dioxide (sub- or SCF-CO2) for improving its structure and properties was constructed for the first time. The achieved results demonstrate that remarkable improvements in the coloration performance of cotton fiber by 71.1 % and the water retention by 1001.2 % against the control could be readily available by employing the flashily-explosion method at a recommended condition with 4-cycle explosion in sub- or SCF-CO2, and system temperature, fluid treatment duration and explosion number exhibited much more pronounced positive influences among all parameters. Additionally, minimal influences from the supercritical explosion on cotton fiber micronaire value, thermal property and tensile breaking strength were also observed. The scanning electron microscopy (SEM) and porosity investigations clearly show that plenty of micropores and/or strip fissures were formed on the fiber surfaces and their inner phases, and notably improved fiber surface area, pore volume and size were also obtained after a subsupercritical flash-explosion. Nuclear magnetic resonance hydrogen spectroscopy (1H NMR) and Fourier transform infrared spectroscopy (FT-IR) analysis disclose that numbers of hydrogen bonds between the fiber macrochains and/or from their intramolecular chains were broken by generating numerous free hydroxyl groups, which reasonably supported the improvements of the dye uptake behaviors and water retention properties, etc. The Energy-dispersive X-ray spectroscopy (EDS) analysis on the fiber cross-sections further confirms that a loosening of the inner aggregation structure of the cotton fiber was achieved after a flash explosion by significantly enhancing its coloration performance, etc. This innovative approach provides a promising idea and possibility as an alternative to chemical methods via mechanically and physically modifying fiber or other materials with sub- or SCF-CO2 fluid in an eco-friendly and sustainable manner.

Anomalous release of indoles from amorphous solid dispersion formed with a polymeric network

AbstractAmorphous solid dispersion (ASDs) is a technique used in the pharmaceutical industry to enhance the solubility, dissolution rate, and bioavailability of poorly soluble drugs. Polymeric materials, and recently polymer gels form and stabilize the amorphous structure by inhibiting the aggregation/precipitation of such drugs. In this work indole, 5-aminoindole and 5-hydroxyindole loaded poly (N-isopropylacrylamide) (PNIPA) hydrogels were studied. Swelling and uptake measurements, X-ray diffraction (XRD), liquid and solid phase nuclear magnetic spectroscopy (NMR) and high sensitivity differential scanning calorimetry (DSC) were applied to understand the drug – matrix interactions affecting the release. We confirmed that the hydrogel fostered the fine uniform distribution of the hydrophobic probe molecules and successfully prevented any crystalline or amorphous phase formation during water removal, leading to a glassy solution, a special form of ASD. Despite the limited difference between their chemical composition the probe molecules showed dissimilar drug release behavior from dried loaded gel disks. While Nuclear Overhauser Enhancement Spectroscopy (NOESY) measurements revealed a “bidental” interaction between 5-hydroxiindole and the polymer, no localized interactions were found for indole. The release of the bidentally linked derivatives is rapid and complete: they act as molecular spacers, promoting the rehydration of the chains. In contrast, part of the indole remains irreversibly trapped being confined between the chains without any orientation, shedding light on the role of the steric consequences of the interaction. Our findings also indicate that such drug delivery compositions should be treated as ternary systems (carrier + drug + liquid) already in the design stages of drug release systems.

A novel biobased prepreg from flax and thermosetting poly(lactic acid): Synthesis, curing and processing

Flax fiber-reinforced thermosetting poly (lactic acid) (PLA) composites, a fully degradable plant fiber-reinforced composites, were prepared by hot-melt pre-impregnation, which consists of two processes, the preparation and curing of the prepreg. Firstly, thermosetting PLA with intrinsic flame-retardancy was synthesized and its molecular structure was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. The non-isothermal viscosity of the thermosetting PLA resin system was investigated to determine the film-formation temperature (55°C) and the impregnation temperature (65°C) during the preparation of the prepreg. On this basis, novel flax fiber-reinforced thermosetting PLA prepreg was prepared and its curing kinetics was investigated using differential scanning calorimetry (DSC). A curing simulation model of the prepreg was developed using the finite difference method, which was used to design and optimize the curing cycle of the flax fiber-reinforced thermosetting PLA prepreg. Finally, the flax fiber-reinforced thermosetting PLA composites with different lay-ups were prepared using the optimal curing cycles and their mechanical and flame retardant properties were investigated, with tensile and flexural strengths up to 128 MPa and 98.8 MPa, and flame retardant ratings up to UL-94 V-1. Overall, the results of this study can provide an important basis for expanding the application of flax fiber reinforced thermosetting PLA composites.