Chemical Configuration Research Articles

Unlocking efficiency in oxygen reduction reaction: Synergistic edge dopants of nitrogen and boron in carbon nano onions

Oxygen reduction reaction (ORR) is a crucial process for energy conversion and storage devices. Despite platinum (Pt) being the state-of-the-art material for ORR, the limited performance of Pt-based catalyst, Pt scarcity, and vulnerability of global supply chains for critical minerals, have made it imperative to develop alternative electrocatalysts that either contain no precious metals at all or require only a very low loading of these valuable resources. In this study, we demonstrate that the incorporation of co-dopants, nitrogen (N) and boron (B), with a dissimilar electronegativity is a promising approach to develop metal-free electrocatalysts for ORR. We discovered that the interaction between N and B plays a vital role in both (i) incorporating the dopants in high-curvature carbon nano-onions (CNOs) and (ii) promoting ORR performance. Tuning the annealing temperature was crucial to achieve a desirable N-B chemical configuration and synergistic effects of N and B on ORR catalysis. Our investigation revealed that N,B-doped CNOs prepared at 700 °C exhibit the best ORR performance in 0.1 M KOH with a dominant 4-electron pathway and excellent durability. Based on X-ray photoelectron spectroscopy (XPS), Raman analysis, and high-resolution scanning transmission electron microscopy (HR-STEM), we conclude that abundant N and B sites, especially N-C-B (isolated) sites, at the edges in conjunction with high surface activity of CNOs are responsible for such outstanding performances. This study provide insights into the design of metal-free catalysts for efficient ORR catalysis, and the importance of alternative electrocatalysts in the current global supply chain disrutipn scenario.

Diastereoselective Cascade Cyclization of Diazoimides with Alkylidene Pyrazolones for Preparation of Pyrazole-Fused Oxa-Bridged Oxazocines.

Under the catalysis of Rh2(OAc)4 (10 mol%) and binapbisphosphine ligand (±)-L3 (20 mol%) in DCE at 80 °C, the cascade cyclization of diazoimides with alkylidenepyrazolones underwent stereoselectively (dr > 20:1), affording pyrazole-fused oxa-bridged oxazocines in reasonable chemical yields. The chemical structure and relative configuration of title products were firmly identified by X-ray diffraction analysis.

Advancements in Laser Powder Bed Fusion of Carbon Nanotubes-Reinforced AlSi10Mg Alloy: A Comprehensive Analysis of Microstructure Evolution, Properties, and Future Prospects

Laser powder bed fusion (L-PBF) stands out as a promising approach within the realm of additive manufacturing, particularly for the synthesis of CNT-AlSi10Mg nanocomposites. This review delves into a thorough exploration of the transformation in microstructure, the impact of processing variables, and the physico-mechanical characteristics of CNT-AlSi10Mg nanocomposites crafted via the L-PBF technique. Moreover, it consolidates a substantial corpus of recent research, proffering invaluable insights into optimizing L-PBF parameters to attain the desired microstructures and enhanced properties. The review centers its attention on pivotal facets, including the dispersion and distribution of CNTs, the formation of porosity, and their subsequent influence on wear resistance, electrical and thermal conductivity, tensile strength, thermal expansion, and hardness. In line with a logical progression, this review paper endeavors to illuminate the chemical composition, traits, and phase configuration of AlSi10Mg-based parts fabricated via L-PBF, juxtaposing them with their conventionally manufactured counterparts. Emphasis has been placed on elucidating the connection between the microstructural evolution of these nanocomposites and the resultant physico-mechanical properties. Quantitative data culled from the literature indicate that L-PBF-produced parts exhibit a microhardness of 151 HV, a relative density of 99.7%, an ultimate tensile strength of 70×103 mm3N.m, and a tensile strength of 756 MPa.

Plant-inspired modification strategy for the large-scale, versatile preparation of cellulose-based products with highly effective and durable UV-protective, antimicrobial, and antiviral performance

Cellulose is a versatile and renewable material used in clinical settings for dressings, masks, and bedding. However, adding functions like UV-shielding, antiviral, and antibacterial properties can be challenging due to its poor adhesion and reduced effectiveness over time. Inspired by the natural structure of plant cell walls, we propose a scalable and versatile strategy by introducing curcumin and lysine to the cellulose surface via the Mannich reaction to achieve a durable antimicrobial and UV-protective cellulose surface. The ensuring chemical configuration was characterized through Nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Additionally, X-ray diffraction analysis confirmed that the modification occurred exclusively at the cellulose surface. We found curcumin-modified sulfated nanocellulose nanofibrils (CL-SCNF) entirely block ultraviolet rays at wavelengths of 200–400 nm (UVA, UVB, and UVC) while providing 82.1 % transparency in the visible spectrum. The resultant silver bonding cellulose products exhibit high antiviral, antibacterial, and antifungal performance against bacterial phage-X174, Escherichia coli, Staphylococcus aureus, and Candida albicans. Furthermore, the strong coordination bonding of silver ions with the β-diketone system endows the final textiles with good washing stability, which can maintain 99 % of antimicrobial activity after repeated washing. This eco-friendly and highly scalable method for fabricating antimicrobial cellulose surfaces will be attractive to manufacturers of protective equipment and textiles, as it offers great potential for applications in a wide range of fields.

Effect of pre-annealing on chemical configuration and heteroatom doping of highly active carbon catalysts for the oxygen reduction reaction

Heteroatom-doped carbon catalysts are promising alternatives to platinum group metal-free catalysts for oxygen reduction reaction (ORR). To enhance the ORR activity of carbon-based catalysts, the break of electroneutrality and number of active sites must be maximized. In this study, an annealing process at a mild temperature was introduced before heteroatom doping to control the content and configuration of the oxygen functional groups on the graphene oxide (GO). Pre-annealing affects the chemical configuration and the porosity of GO such that the epoxy groups are converted into carbonyl groups accompanying the defect formation. Interestingly, The carbonyl-enriched environment allowed ammonia borane, as a dopant with nitrogen and boron atoms, the enhanced doping performance, inducing the formation of higher number of heteroatom doping sites and additional defects in the graphene lattice. The aBNG-150 catalyst demonstrated outstanding ORR activity in both half- and single-cell evaluations because it had the highest heteroatom content and meso/macropores derived from the elimination of oxygen functional groups, which can facilitate ORR catalytic activity and O2 diffusion pathway. Therefore, we believe that this approach provides an effective route for synthesizing carbon-based catalysts with remarkable ORR performances.

Visualizing Penetration of Fluorescent Dye through Polymer Coatings.

Understanding how small molecules penetrate and contaminate polymer films is of vital importance for developing protective coatings for a wide range of applications. To this end, rhodamine B fluorescent dye is visualized diffusing through polystyrene-polydimethylsiloxane block copolymer (BCP) coatings using confocal microscopy. The intensity of dye inside the coatings grows and decays non-monotonically, which is likely due to a combination of dye molecule transport occurring concurrently in different directions. An empirical fitting equation allows for comparing the contamination rates between copolymers, demonstrating that dye penetration is related to the chemical makeup and configuration of the BCPs. This work shows that confocal microscopy can be a useful tool to visualize the transport of a fluorophore in space and time through a coating.

Novel Electrospun Polymeric Nanofibers Loaded Different Medicaments as Drug Delivery Systems for Regenerative Endodontics.

A combination of antibiotics, including metronidazole (MET), ciprofloxacin (CIP), and minocycline (MINO), has been demonstrated to disinfect bacteria in necrotic teeth before regenerative processes. It has been presented clinically that antibiotic pastes may drive to possible stem cell death, creating difficulties in removing from the canal system, which can limit the regenerative procedure. This study was designed to (1) synthesize nanofibrous webs containing various concentrations of different medicaments (triple, double, and calcium hydroxide, Ca(OH)2), and (2) coat the electrospun fibrous gutta-percha (GP) cones. Poly(vinylpyrrolidone) (PVP)-based electrospun fibrous webs were processed with low medicament concentrations. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS) were carried out to investigate fiber morphology and antibiotic incorporation, and characterize GP-coated fibrous webs, respectively. The chemical and physical properties of dentine were determined via fourier transform infrared spectroscopy (FTIR) and Nano-SEM, respectively. The antimicrobial properties of the different fibrous webs were assessed against various bacteria by direct nanofiber/bacteria contact. Cytocompatibility was measured by applying the MTT method. The mean fiber diameter of the experimental groups of medicament-containing fibers ranged in the nm scale and was significantly smaller than PVP fibers. EDX analysis confirmed the presence of medicaments in the nanofibers. XPS analysis presented a complete coating of the fibers with GPs; FTIR and Nano-SEM showed no chemical and physical configuration of intracanal medicaments on the dentine surface. Meanwhile, nanofibrous webs led to a significant reduction in the percentage of viable bacteria compared to the negative control and PVP. Our findings suggest that TA-NFs, DA-NFs, and Ca(OH)2)-NFs coated GP cones have significant potential in eliminating intracanal bacteria, having cell-friendly behavior and clinical usage features.

Stimuli-Responsive Design of Metal-Organic Frameworks for Cancer Theranostics: Current Challenges and Future Perspective.

Scientific fraternity revealed the potential of stimuli-responsive nanotherapeutics for cancer treatment that aids in tackling the major restrictions of traditionally reported drug delivery systems. Among stimuli-responsive inorganic nanomaterials, metal-organic frameworks (MOFs) have transpired as unique porous materials displaying resilient structures and diverse applications in cancer theranostics. Mainly, it demonstrates tailorable porosity, versatile chemical configuration, tunable size and shape, and feasible surface functionalization, etc. The present review provides insights into the design of stimuli-responsive multifunctional MOFs for targeted drug delivery and bioimaging for effective cancer therapy. Initially, the concept of cancer, traditional cancer treatment, background of MOFs, and approaches for MOFs synthesis have been discussed. After this, applications of stimuli-responsive multifunctional MOFs-assisted nanostructures that include pH, light, ions, temperature, magnetic, redox, ATP, and others for targeted drug delivery and bioimaging in cancer have been thoroughly discussed. As an outcome, the designed multifunctional MOFs showed an alteration in properties due to the exogenous and endogenous stimuli that are beneficial for drug release and bioimaging. The several reported types of stimuli-responsive surface-modified MOFs revealed good biocompatibility to normal cells, promising drug loading capability, target-specific delivery of anticancer drugs into cancerous cells, etc. Despite substantial progress in this field, certain crucial issues need to be addressed to reap the clinical benefits of multifunctional MOFs. Specifically, the toxicological compatibility and biodegradability of the building blocks of MOFs demand a thorough evaluation. Moreover, the investigation of sustainable and greener synthesis methods is of the utmost importance. Also, the low flexibility, off-target accumulation, and compromised pharmacokinetic profile of stimuli-responsive MOFs have attracted keen attention. In conclusion, the surface-modified nanosized design of inorganic diverse stimuli-sensitive MOFs demonstrated great potential for targeted drug delivery and bioimaging in different kinds of cancers. In the future, the preference for stimuli-triggered MOFs will open a new frontier for cancer theranostic applications.

A Concise Review of Common Plant-derived Compounds as a Potential Therapy for Alzheimer's Disease and Parkinson's Disease: Insight into Structure-Activity-Relationship.

Alzheimer's disease (AD) and Parkinson's disease (PD) are the two most common neurological illnesses that affect people in their later years. Memory loss is the hallmark of Alzheimer's disease, while dyskinesia, or loss of mobility, is associated with muscle rigidity and tremors in PD. Both diseases are unrelated, however, they do have a few similarities associated with extrapyramidal abnormalities, particularly stiffness, which has been linked to concomitant PD in many AD patients. Increased levels of IL-1, IL-6, and TNF in the AD and PD patients can be regarded as evidence of systemic inflammation associated with each of these neurodegenerative disorders. One of the primary variables in the progression of neurodegenerative disorders is oxidative stress. Many medicinal plants and their secondary metabolites have been claimed to be able to help people with neurodegenerative disorders like AD and PD. Anti-inflammatory, antioxidant, antiapoptotic, monoamine oxidase inhibition, acetylcholinesterase, and neurotrophic pursuits are among the major mechanisms identified by which phytochemicals exert their neuroprotective effects and potential maintenance of neurological health in old age. In regard to neurodegenerative disorders, numerable plant-based drugs like alkaloids, iridoids, terpenes, and flavones are employed for the treatment. Structure-activity relationships (SAR) and quantitative structure-activity relationships (QSAR) are used to investigate the link between bioactivity and the chemical configuration of substances. The SAR and QSAR of natural plant components employed in AD and PD are discussed in the current review.

Effect of Structural Changes at Various Length Scales in SiVOC Ceramic Nanocomposites on Electrocatalytic Performance for the Oxygen Reduction Reaction.

Polymer-derived processing of ceramics (PDC) is an efficient technique to prepare porous nanocomposites with precise control over their phase composition and in relation to the Si-based ceramic matrix containing free carbon. The microstructure of these nanocomposites can be fine-tuned at the molecular scale for obtaining necessary properties by tailoring the chemical configuration of the preceramic polymer. In the present work, vanadium-based nanocomposites were synthesized as oxygen reduction reaction (ORR) catalysts with the objective of elucidating the effect of microstructure changes on catalytic efficiency. For this purpose, a single-source precursor (SSP) was synthesized by crosslinking phenyl- and hydrido-substituted polysiloxane and vanadium acetylacetonate followed by pyrolysis at 1100 °C. The resulting solid was composed of sparsely distributed nanodomains of vanadium carbide (VC) crystals precipitated within an amorphous silicon oxycarbide (-Si-O-C-) matrix. High-temperature treatment of the pyrolyzed samples beyond 1300 °C induced the crystallization of β-SiC as well as VC. Furthermore, Raman spectroscopy confirmed the segregation of sp2-hybridized, turbostratic free carbon. The samples exposed to 1300 °C revealed a specific surface area of 239 m2/g. The electrocatalytic activity of the sample heat-treated at 1300 °C showed the best performance with respect to the ORR performance with onset potential (Eo) and half-wave potential (E1/2) values of 0.81 and 0.72 V, respectively. In addition, improved kinetics with a Tafel slope of 57 mV/dec and enhanced current density in the diffusion-controlled region (Id) of 3.7 mA/cm2 were observed for this sample. The increase in Eo was attributed to the optimal interfacial characteristics between the VC and SiOC matrix with better embedment of VC with free carbon through V-C bonds. The higher E1/2 and faster kinetics are because of the higher electronic conductivity caused by the free carbon effectively connecting metallic VC crystallites. Besides, the higher specific surface area of this sample enhanced Id.

Ultrasound-Auxiliary Preparation of Antifouling Cu-Enriched Titanium Oxide Ceramic Layer

The limited antifouling capability of Ti-based components could jeopardize their applications in petroleum engineering. In this work, a Cu-enriched TiO2 coating has been fabricated using an ultrasound-auxiliary micro-arc oxidation (UMAO) method. The Cu enrichment of TiO2 affects its morphology, phase component and chemical configuration, leading to the slightly enhanced corrosion resistance of the Cu-enriched TiO2 coating relative to that free of Cu. Finally, the antifouling capability against sulphate-reducing bacteria (SRB) is significantly improved by preventing the formation of biofilm after the Cu enrichment of TiO2, which potentially widens its application in petroleum engineering.

Superhydrophobic Conductive Suede Fabrics Based on Carboxylated Multiwalled Carbon Nanotubes and Polydopamine for Wearable Pressure Sensors

Textile-based pressure sensors have attracted considerable attention due to their potential to detect vital signals in humans, enhance sports performance, and facilitate human–machine interactions. However, practical challenges, such as unstable assembly structures, weak interfacial bonds with functional materials, and incompatibility with current established finishing technologies in production, remain significant obstacles to their widespread applications. This research explores commercially available suede fabric as a promising substrate for pressure sensing. The conductive suede sensor was readily by integrating carboxylated multiwalled carbon nanotubes (C-MWCNTs) and polydopamine (PDA) and subsequently modifying it with hexadecyltrimethoxysilane to achieve a superhydrophobic surface. The resulting suede sensor, featuring a robust PDA-(C-MWCNTs)-HDTMS chemical configuration, exhibited satisfactory hydrophobicity, excellent stability, and repeatability, capable of detecting pulse, throat movement, and daily human motions. Furthermore, the properties of the suede sensor can be well preserved after 60 min of machine washing and ultrasonic cleaning, highlighting its potential in practical applications. This study provides an environmentally stable, lightweight, and well-structured substrate for high-performance electronic textiles suitable for large-scale production.

Giant Negative Thermopower Enabled by Bidirectionally Anchored Cations in Multifunctional Polymers.

The lack of high-quality ionic thermoelectric materials with negative thermopowers has stimulated scientists' broad research interest. The effective adjustment of the interaction between ions and a polymer network is an important way to achieve high-quality ion thermoelectric properties. Integrating different types of ion-polymer interactions into the same thermoelectric device seems to lead to unexpected gains. In this work, we propose a strategy for bidirectionally anchoring cations to synergistically generate a giant negative thermopower and high ionic conductivity. This is mainly achieved through synergistic ion-polymer coordination and Coulomb interactions. An ionic thermoelectric material was prepared by infiltrating a polycation electrolyte [poly(diallyldimethylammonium chloride)] with CuCl2 into the poly(vinyl alcohol)-chitosan aerogel. The confinement effect of copper-coordinated chitosan on cations, the repulsive property of the polycationic electrolyte on cations, and the unique chemical configuration of a transition metal chloride anion ([CuCl4]2-) are the fundamental guarantees for achieving a thermopower of -28.4 mV·K-1. Moreover, benefiting from the high charge density of the polycationic electrolyte, we obtain an ionic conductivity of 40.5 mS·cm-1. These findings show the application prospect of synergistic different types of ion-polymer interactions in designing multifunctional ionic thermoelectric materials.

Fouling resistance study in industrial tubular reactor for low density polyethylene production

Fouling is the development and buildup of unwelcome elements on the surface of processing equipment. Fouling study in LDPE production via tubular reactor is very important with regard to safety, economic and productivity. However, the fouling study in LDPE production was rarely reported in the literature due to complex chemical reaction and reactor configuration. In this work, the overall heat transfer coefficient (U) computed by component’s physical properties (method 1) and log mean temperature difference of plant data (method 2) were studied. The U obtained from the correlation method is larger than plant data. The U variations obtained from industrial data were employed in this work to determine the maximum reactor fouling resistance Rfmax. The Rf reaction zone is significantly lesser than the Rf cooling zone.The fouling investigation utilized fouling resistance (Rf) as the fouling measurement. Rf is signified by the alteration of U dynamically over ten hours. The Rfmax achieved is 50.0 cm2.s.K/cal. The Rfmax value obtained were then applied as a constraint for the optimization study.

Potential Role of Carbon Nanomaterials in the Treatment of Malignant Brain Gliomas.

Malignant gliomas are the most common primary brain tumors in adults up to an extent of 78% of all primary malignant brain tumors. However, total surgical resection is almost unachievable due to the considerable infiltrative ability of glial cells. The efficacy of current multimodal therapeutic strategies is, furthermore, limited by the lack of specific therapies against malignant cells, and, therefore, the prognosis of these in patients is still very unfavorable. The limitations of conventional therapies, which may result from inefficient delivery of the therapeutic or contrast agent to brain tumors, are major reasons for this unsolved clinical problem. The major problem in brain drug delivery is the presence of the blood-brain barrier, which limits the delivery of many chemotherapeutic agents. Nanoparticles, thanks to their chemical configuration, are able to go through the blood-brain barrier carrying drugs or genes targeted against gliomas. Carbon nanomaterials show distinct properties including electronic properties, a penetrating capability on the cell membrane, high drug-loading and pH-dependent therapeutic unloading capacities, thermal properties, a large surface area, and easy modification with molecules, which render them as suitable candidates for deliver drugs. In this review, we will focus on the potential effectiveness of the use of carbon nanomaterials in the treatment of malignant gliomas and discuss the current progress of in vitro and in vivo researches of carbon nanomaterials-based drug delivery to brain.

Synthesis of Ammonium-Based ILs with Different Lengths of Aliphatic Chains and Organic Halogen-Free Anions as Corrosion Inhibitors of API X52 Steel.

In the present work, synthesis and characterization of 15 ionic liquids (ILs) derived from quaternary ammonium and carboxylates were carried out in order to proceed to their evaluation as corrosion inhibitors (CIs) of API X52 steel in 0.5 M HCl. Potentiodynamic tests confirmed the inhibition efficiency (IE) as a function of the chemical configuration of the anion and cation. It was observed that the presence of two carboxylic groups in long linear aliphatic chains reduced the IE, whereas in shorter chains it was increased. Tafel-polarization results revealed the ILs as mixed-type CIs and that the IE was directly proportional to the CI concentration. The compounds with the best IE were 2-amine-benzoate of N,N,N-trimethyl-hexadecan-1-ammonium ([THDA+][-AA]), 3-carboxybut-3-enoate of N,N,N-trimethyl-hexadecan-1-ammonium ([THDA+][-AI]), and dodecanoate of N,N,N-trimethyl-hexadecan-1-ammonium ([THDA+][-AD]) within the 56-84% interval. Furthermore, it was found that the ILs obeyed the Langmuir adsorption isotherm model and inhibited the corrosion of steel through a physicochemical process. Finally, the surface analysis by scanning electron microscopy (SEM) confirmed less steel damage in the presence of CI due to the inhibitor-metal interaction.

Rheological modeling and microstructural evaluation of oily sludge modified bitumen

The disposal of oily sludge (OS) and depletion of crude oil reservoirs has become a global problem for the petroleum industries. The rising cost of bituminous materials is also attributed to the depletion of crude oil reservoirs. Incorporating OS in the production of bitumen can reduce waste generation, thereby ensuring sustainability in petroleum industries. This study carried out a series of physicochemical, rheological and morphological tests to examine the suitability of OS as a bitumen modifier. OS and binders were subjected to Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) to characterize their morphological and chemical configuration. Using a dynamic shear rheometer (DSR) and response surface methodology (RSM), the performance characteristics of binders were analyzed and modeled. FTIR showed the identical functional groups responsible for the compatibility of OS and bitumen. Fit statistics and diagnostic graphs showed the significance and adequacy of the quadratic model for rutting and fatigue factors. Response surface plots showed that OS improved the fatigue resistance of bitumen. The OS up to 8 % addition improves fatigue resistance while keeping the performance grade (PG) identical to that of base bitumen.

Radar Attenuation in Enceladus' Ice Shell: Obstacles and Opportunities for Constraining Shell Thickness, Chemistry, and Thermal Structure

AbstractEnceladus is a dynamic icy moon of Saturn and a leading target for future planetary missions focused on the search for life beyond Earth. For such missions, instruments that can provide geophysical and geochemical context for ice shell and ocean processes are critical to evaluate whether conditions are suitable for life and biosignature detection. Radar sounding is a powerful geophysical technique to probe the thermophysical and chemical properties of icy moons, like Enceladus, and to investigate the subsurface context for the exchange of material and energy between their subsurface oceans, ice shells, and plumes. To inform the scientific potential and instrument performance demands of such a radar‐sounding investigation of Enceladus' ice shell, we adapt and extend previous radar attenuation analysis done for Europa to the configuration and conditions of Enceladus. We also discuss how attenuation (both as an obstacle for the detection of ice shell reflectors and as a signal itself) can help constrain the thermal, physical, and chemical configuration of Enceladus' ice shell and reveal the processes governing the moon's ocean/shell/plume system.

Optical and radiation absorption properties of bismuth-borate glasses doped with Ce4 +, Nd3 +, and Sm3 +

Three bismuth-borate glasses with the chemical configuration 15Bi2O3-75 H3BO2-10CeO2, 15Bi2O3-75 H3BO2-10Nd2O3, and 15Bi2O3-75 H3BO2-10Sm2O3 and coded as BHB-Ce, BHB-Nd, and BHB-Nd were investigated for their optical and gamma-radiation absorption behaviour. Optical parameters of the glasses such as the molar refractivity, Rm, molar polarizability, αm, reflection loss RL, optical transmission T, metallization criterion M, static dielectric constant εstatic, and optical dielectric constant εoptical were calculated using standard theoretical models. The mass attenuation coefficient μ/ρof the glass samples was estimated by FLUKA simulations and XCOM for discrete photon beams with energies of 0.282, 0.662, 1.33, and 2.51 MeV. The value of Vm was 21.35, 22.61, and 19.60 cm3/mol for BHB-Ce, BHB-Nd, and BHB-Sm, respectively. Also, the highest Rm (16.52 cm3/mol) and αm (6.56 ×10−24 cm3) were obtained for BHB-Ce, while the lowest value was recorded for BHB-Nd (12.035 cm3/mol and 4.78 ×10−24 cm3). Other optical parameters varied with the dopant ion. The photon attenuation coefficient obtained from XCOM calculation and simulations agreed within a 2.90% margin. The μ/ρ varied within the interval 0.0422–0.3086 cm2/g for BHB-Ce, 0.0420–0.3005 cm2/g for BHB-Nd and 0.0420–0.3029 cm2/g for BHB-Sm. The half-value layers (HVLs) vary from 0.3948 cm to 2.8854 cm for BHB-Ce, from 0.3782 cm to 2.7063 cm for BHB-Nd and from 0.3223 cm to 2.3252 cm for BHB-Sm. Based on the values of the photon shielding parameters, the investigated glasses showed better ability to absorb photons compared to conventional shields such as barite concrete, ordinary concrete, and some commercial glass shields. The analysis of the optical and radiation absorption parameters shows that the BHB-glasses are useful in optical and gamma-radiation absorption technologies.

Correlation vs. exchange competition drives the singlet-triplet excited-state inversion in non-alternant hydrocarbons.

In this work, we focus on the understanding of the driving force behind the S1-T1 excited-state energy inversion (which would thus violate Hund's rule, making the S1 state lower in energy than the T1 state) of two non-benzenoid non-alternant hydrocarbons, composed of odd-membered rings. The molecules considered here have identical chemical composition but different atomic configuration in space. The delicate interplay between structural and electronic factors that might induce inversion and its energy extension, only by a few meV, is systematically investigated here by state-of-the-art calculations. Qualitative and quantitative accurate predictions are obtained employing post-HF methods, thanks to the balanced and careful inclusion of electron correlation effects. The obtained results might guide and rationalize new searches for molecules violating Hund's rule, concomitantly demonstrating the importance of key contributions from the theoretical method of choice.