Experimental Model For Study Research Articles

Experimental and kinetic modeling study of tar partial oxidative reforming by dielectric barrier discharge plasma using toluene as a model compound

In this study, partial oxidation of toluene as a biomass tar surrogate was carried out in a dielectric barrier discharge (DBD) plasma reactor. In order to understand the reaction characteristics and thus potential of the approach, the effect of reaction temperature, O2/toluene molar ratio (OTR) and discharge power on performances was investigated by experiments and kinetic modeling. The results showed that the three factors could change the E/n and hence the G-values of species, as well as alter O2 concentration in background gas and input energy, leading to the variation in active species production and thus, the performance. Appropriate high temperatures, as well as higher OTRs and discharge power obtained better performances by promoting toluene destruction and gas product production. Excited N2 species play a crucial role in the process, by means of participating in reactions directly and strongly influencing on the production of secondary active species. At 300 °C, the highest toluene conversion of 100.0 % with an energy efficiency of 25.7 g/kWh was achieved without catalysts usage, a comparable performance as compared to the steam reforming by plasma catalysis, demonstrating the potential of this method for the purification of gasification gases. Furthermore, based on the rate of production (ROP) and sensitivity analyses of the model developed, as well as experimental results, the reaction mechanism was proposed.

Experimental study of a multimechanism formation pressure prediction model influenced by shale content

The precise prediction of abnormally high-pressure formations has always been a hot topic in oil and gas exploration and development. In the Yingqiong Basin of the South China Sea, abnormally high-pressure formations are widespread, with narrow drilling safety windows and frequent accidents caused by the limited accuracy of formation pressure prediction. To improve the prediction accuracy of formation pressure, based on the characterization and classification method of the pressure forming mechanism of sediment and mechanics and considering the influence of shale content on pore pressure, in this study, soil consolidation acoustic experiments were carried out using real rock debris soil in a block of strata in this area. We obtained the response laws of parameters such as acoustic velocity and density under different pressure-forming mechanisms and established an acoustic density intersection chart exhibiting the influence of shale content. The experimental results show that under the same loading mechanism and conditions, the higher the shale content in the core is, the smaller the density, the smaller the acoustic velocity, and the smoother the trend line of the acoustic density intersection chart. When the shale content ≥0.5, under the unloading mechanism, the higher the shale content of the rock is, the further away the unloading trend line is from the loading trend line, and the greater the difference in the changes in the acoustic properties of the rock compared to the density properties. Moreover, the experimental conclusion also verified why the pressure formation mechanism in non-shale formations is difficult to determine. Based on the experimental results, the traditional Bowers model was improved, and a multimechanism formation pressure prediction model for the influence of shale content was established. The established model was validated and compared. The evaluation results showed that compared to the traditional model, the maximum prediction error of the multimechanism prediction model was reduced by approximately 20%, and the average prediction error was approximately 3%. This model effectively improved the prediction accuracy of the formation pore pressure.

Germination of bean seeds (Vigna unguiculata L. Walp.) in strong electric fields

This paper presents a tutorial for the germination of bean seeds (Vigna unguiculata L. Walp.) in strong electrostatic fields up to 1240 V/cm. The seeds were allowed to germinate under different electric field strengths for 48 h. Although most of such germination experiments did not show any visible effect, the field strength of 945 V/cm strongly increased the seedling's vigor during the early growth stage. In the end, 30 % more yield was obtained from stimulated seeds when compared to the control group. This article postulates for the first time a hypothesis of the mechanism of action of the electric field during germination. In biological cells of any species, water confined between narrow surfaces can undergo a phase transition that shifts its melting point to higher temperatures when an external electric field is applied. This effect has already been known as electrofreezing, and has been confirmed by several experimental and molecular modeling studies. As a consequence, the transport kinetics of molecules across cell organelle membranes might be altered, which in turn leads to different plant properties.With emphasis on the presented method, this work reports:•An inexpensive electric circuit for the generation of strong electric fields•Instructions regarding the setup and operation of an adequate germination chamber

An experimental and kinetic modeling study of CO2 hydrogenation to CO over Cu-Al catalyst utilizing MFB-TGA-MS

Carbon capture, utilization, and storage (CCUS) are essential technologies for realizing carbon neutrality in the context of fossil fuel decarbonization. Integrated carbon capture and utilization, in conjunction with the reverse water gas shift reaction (ICCU-RWGS), presents a promising strategy for the in-situ conversion of CO2. This approach mitigates the energy penalties associated with CO2 capture and eliminates the additional costs associated with storage and transportation. In this study, we employed a Cu-Al composite catalyst, prepared using the impregnation method, for ICCU-RWGS, with a specific focus on CO2 hydrogenation. The kinetics of hydrogenation for the Cu-Al catalyst were comprehensively investigated using micro-fluidized bed thermogravimetric analysis coupled with mass spectrometry (MFB-TGA-MS). The results indicate that, when subjected to experimental conditions involving 800 °C, 20 vol.% CO2, 30 vol.% H2, and a sample mass of 1 g, the comprehensive evaluation reveals a CO2 conversion rate of 43.67 %. This conversion is accompanied by 100 % CO selectivity and a reaction rate of 0.10 mmol·g−1·s−1, respectively. Furthermore, we calculated the kinetic parameters for the CO2 hydrogenation by analyzing the MFB-TGA-MS data, utilizing the simplified K-L model for fluidized beds. The results indicated an activation energy of 55.8 kJ∙mol−1. These findings highlight the effectiveness of ICCU-RWGS methodologies, especially concerning CO2 hydrogenation, and present a compelling case for their further commercialization.

Role of O2 on nitrous oxide fuel blend ethylene auto-ignition sensitivity

An experimental and kinetic modeling study of the influence of O2 addition on the ignition behaviors of Ar diluted nitrous oxide/ethylene blend was performed. Ignition delay time (IDT) measurements were taken by detecting pressure evolution profiles in a heated rapid compression machine (RCM) at temperatures and pressures ranging from 910–1500 K to 35–45 bar. Results show that the addition of O2 significantly promotes the ignition of N2O/C2H4/Ar blend. With the O2 blending ratio increase from 10 % to 100 %, the IDT first decreases and then increases. Subsequently, the IDT data were employed to validate several kinetic models in literature. A reaction model developed in our previous work [Combustion and Flam, 2020, 221: 64-73] can reproduce the measured data and predict the promotion effect of O2 on N2O/C2H4/Ar blend well. Reaction pathway and rate of production (ROP) analyses show that high decomposition temperature of N2O inhibits the ignition of N2O/C2H4/Ar blend, whose ignition is mainly driven by reactions of N2O (+M) = N2 + O (+M) and N2O + H = N2 + OH. The dominant pathway is chain branching process: C2H4 + H/OH→C2H3 (+M)→C2H2 + O→HCCO + H2→CH2CO + H→CH3CO (+M)→CO + CH3. However, the presence of O2 in mixture induces reaction flux changes and decreases the global activation energy for chemical reaction. C2H3 radical is the main intermediate product during the ignition initial stage of C2H4 blends, whose ROP can reflect ignition process of C2H4 blends. For N2O/C2H4/O2/Ar and C2H4/O2/Ar ignition, C2H3 radical pool can be rapidly established via H-abstraction reaction of C2H4. However, the reaction of N2O + H = N2 + OH enhances the ROP of OH radical in N2O/C2H4/O2/Ar blends, resulting in C2H3 radical pool rapid establishment and a faster ignition.

Experimental and thermodynamic modeling study of phase equilibria in the PbO–NiO–SiO2 system

AbstractAn integrated experimental and thermodynamic modeling investigation of the phase equilibria in the PbO–NiO–SiO2 system in air and also in equilibrium with liquid metal has been undertaken to better characterize the chemical reactions taking place in the Ni‐containing Pb processing slags. New experimental phase equilibria data at 720°C–1740°C were obtained for this system using high‐temperature equilibration of synthetic mixtures with predetermined compositions in sealed silica ampoules or in Au/Pt–Ir foils, a rapid quenching technique, and electron probe x‐ray microanalysis of the equilibrated phase compositions. Phase equilibria and liquidus isotherms in the quartz/tridymite/cristobalite (SiO2), olivine (Ni2SiO4), monoxide (NiO), Ni‐barysilite (Pb8NiSi6O21), massicot (PbO), and di‐lead silicate (Pb2SiO4) primary phase fields were revealed and the extent of the high‐SiO2 two‐liquid immiscibility gap in equilibrium with cristobalite was determined. New experimental data were used in the development of a thermodynamic database describing this ternary system. Also, modeling revision of the NiO–SiO2 binary system was conducted, resulting in a smaller miscibility gap in ternary systems that was closer to the experimental results.

An experimental and detailed kinetic modeling study of the auto-ignition of NH3/diesel mixtures: Part 2- Wide pressures up to 120bar

Ammonia (NH3) blending combustion strategy has been regarded as a high-efficient form of NH3 utilization. To understand the high-pressure gas-phase auto-ignition characteristics of NH3 blending with diesel, the ignition delay times of NH3/diesel mixtures with high NH3 energy fractions of 70%, 80% and 90% were measured in an ultrahigh-pressure rapid compression machine, at high pressures of 50–120 bar, temperatures of 755–996 K, and equivalence ratios of 0.5–1.5. As a consecutive study of Part 1 (Combust. Flame, 251 (2023), 112391), this study mainly focuses on the auto-ignition characteristics and oxidation mechanism of NH3/diesel mixtures at pressures higher than 50 bar. The ignition-promoting effect of increasing pressure from 50 to 120 bar was experimentally confirmed. Moreover, the increase of the diesel energy fraction, equivalence ratio, and oxygen concentration was found to decrease the ignition delay time of the NH3/diesel mixtures. The chemical reaction mechanism proposed in Part 1 was utilized to simulate the auto-ignition of the NH3/diesel mixtures. Simulation results show that the mechanism was able to quantitatively capture the ignition delay times of the NH3/diesel mixtures at the wide pressures. The cross-reactions between NH3 and diesel, especially reaction RH + NH2 = R + NH3, was found to play a key role in the correct prediction of auto-ignition at high pressure. In addition, it is revealed the effect of pressure is closely related to OH production reactions 2OH (+M) = H2O2 (+M) and NO + HO2 = NO2 + OH, the rate of which increase with rising pressure. The reaction H2NO + O2 = HNO + HO2 is an important pathway where oxygen concentration affects NH3/diesel mixture auto-ignition.

Direct probing of acylperoxy radicals during ozonolysis of α-pinene: constraints on radical chemistry and production of highly oxygenated organic molecules

Abstract. Acylperoxy radicals (RO2) are key intermediates in the atmospheric oxidation of organic compounds and different from the general alkyl RO2 radicals in reactivity. However, direct probing of the molecular identities and chemistry of acyl RO2 remains quite limited. Here, we report a combined experimental and kinetic modeling study of the composition and formation mechanisms of acyl RO2, as well as their contributions to the formation of highly oxygenated organic molecules (HOMs) during ozonolysis of α-pinene. We find that acyl RO2 radicals account for 67 %, 94 %, and 32 % of the highly oxygenated C7, C8, and C9 RO2, respectively, but only a few percent of C10 RO2. The formation pathway of acyl RO2 species depends on their oxygenation level. The highly oxygenated acyl RO2 (oxygen atom number ≥6) are mainly formed by the intramolecular aldehydic H shift (i.e., autoxidation) of RO2, while the less oxygenated acyl RO2 (oxygen atom number <6) are basically derived from the C–C bond cleavage of alkoxy (RO) radicals containing an α-ketone group or the intramolecular H shift of RO containing an aldehyde group. The acyl-RO2-involved reactions explain 50 %–90 % of C7 and C8 closed-shell HOMs and 14 % of C10 HOMs, respectively. For C9 HOMs, this contribution can be up to 30 %–60 %. In addition, acyl RO2 contribute to 50 %–95 % of C14–C18 HOM dimer formation. Because of the generally fast reaction kinetics of acyl RO2, the acyl RO2 + alkyl RO2 reactions seem to outcompete the alkyl RO2 + alkyl RO2 pathways, thereby affecting the fate of alkyl RO2 and HOM formation. Our study sheds lights on the detailed formation pathways of the monoterpene-derived acyl RO2 and their contributions to HOM formation, which will help to understand the oxidation chemistry of monoterpenes and sources of low-volatility organic compounds capable of driving particle formation and growth in the atmosphere.

Insulin and aging - a disappointing relationship.

Experimental studies in animal models of aging such as nematodes, fruit flies or mice have observed that decreased levels of insulin or insulin signaling promotes longevity. In humans, hyperinsulinemia and concomitant insulin resistance are associated with an elevated risk of age-related diseases suggestive of a shortened healthspan. Age-related disorders include neurodegenerative diseases, hypertension, cardiovascular disease, and type 2 diabetes. High ambient insulin concentrations promote increased lipogenesis and fat storage, heightened protein synthesis and accumulation of non-functional polypeptides due to limited turnover capacity. Moreover, there is impaired autophagy activity, and less endothelial NO synthase activity. These changes are associated with mitochondrial dysfunction and oxidative stress. The cellular stress induced by anabolic activity of insulin initiates an adaptive response aiming at maintaining homeostasis, characterized by activation of the transcription factor Nrf2, of AMP activated kinase, and an unfolded protein response. This protective response is more potent in the long-lived human species than in short-lived models of aging research resulting in a stronger pro-aging impact of insulin in nematodes and fruit flies. In humans, resistance to insulin-induced cell stress decreases with age, because of an increase of insulin and insulin resistance levels but less Nrf2 activation. These detrimental changes might be contained by adopting a lifestyle that promotes low insulin/insulin resistance levels and enhances an adaptive response to cellular stress, as observed with dietary restriction or exercise.

Technological Innovations in Shoulder Replacement: Current Concepts and the Future of Robotics in Total Shoulder Arthroplasty.

Total shoulder arthroplasty (TSA) has been rapidly evolving over the last several decades, with innovative technological strategies being investigated and developed in order to achieve optimal component precision, joint alignment and stability, preserve implant longevity, and improve patient outcomes. Future advancements such as robotic-assisted surgeries, augmented reality, artificial intelligence, patient-specific instrumentation (PSI) and other peri/preoperative planning tools will continue to revolutionize TSA. Robotic-assisted arthroplasty is a novel and increasingly popular alternative to the conventional arthroplasty procedure in the hip and knee but has not yet been investigated in the shoulder. Therefore, the purpose of this study was to conduct a narrative review of the literature on the evolution and projected trends of technological advances and robotic assistance in total shoulder arthroplasty. A narrative synthesis method was employed for this review, rather than a meta-analysis or systematic review of the literature. This decision was based on two primary factors: (1) the lack of eligible, peer-reviewed studies with high quality level of evidence available for review on robotic-assisted shoulder arthroplasty, and (2) a narrative review allows for a broader scope of content analysis, including a comprehensive review of all technological advances-including robotics-within the field of TSA. A general literature search was performed using PubMed, Embase, and Cochrane Library databases. These databases were queried by two independent reviewers from database inception through November 11, 2022, for all articles investigating the role of robotics and technology-assistance in total shoulder arthroplasty. Inclusion criteria included studies describing "shoulder arthroplasty" and "robotics". After exclusion criteria were applied, four studies on robotic-assisted TSA were described in the review. Given the novelty of this technology and limited data on robotics in TSA, these studies consisted of a literature review, non-validated experimental biomechanical studies in sawbones models, and preclinical proof-of-concept cadaveric studies using prototype robotic technology primarily in conjunction with patient specific instrumentation (PSI). The remaining studies described the technological advancements in TSA, including PSI, computer-assisted navigation (CAS), artificial intelligence, machine learning, and virtual/augmented/mixed reality. Although not yet commercially available, robotic-assisted TSA confers the theoretical advantages of precise humeral head cuts for restoration of proximal humerus anatomy (RPHA), more accurate glenoid preparation, and improved soft-tissue assessment in limited early studies. The evidence for the use of robotics in THA and TKA demonstrates improved component accuracy, more precise radiographic measurements, and improved early/mid-term patient-reported and functional outcomes. While no such data currently exists for shoulder arthroplasty given that the technology has not yet been commercialized, the lessons learned from robotic hip and knee surgery in conjunction with its rapid adoption suggests robotic-assisted TSA is on the horizon of innovation. By achieving a better understanding of the past, present and future innovations in TSA through this narrative review, orthopedic surgeons can be better prepared for future applications.

УВЕЛИЧЕНИЕ ЭНЕРГОЕМКОСТИ ЗАБИВКИ И СОПРОТИВЛЯЕМОСТИ МОДЕЛИ СВАИ С УШИРЕНИЯМИ ПРИ ПОДСЫПКЕ СЫПУЧИХ МАТЕРИАЛОВ

The results of experimental studies of models of piles with 4 widenings performed under laboratory conditions with the addition of bulk materials are presented. It was revealed that the introduction of bulk materials increases the energy costs of clogging models up to 1.14-1.66 times. At the same time, the type of filling material affects the energy intensity of pile driving. It was also found that the resistance of pile models to static vertical loads increased up to 1.15-1.68 times when introducing bulk materials during clogging. It is shown that the type of filling material influences the resistance of pile models to the action of vertical static load.

УВЕЛИЧЕНИЕ ЭНЕРГОЕМКОСТИ ЗАБИВКИ И СОПРОТИВЛЯЕМОСТИ МОДЕЛИ СВАИ С УШИРЕНИЯМИ ПРИ ПОДСЫПКЕ СЫПУЧИХ МАТЕРИАЛОВ

The results of experimental studies of models of piles with 4 widenings performed under laboratory conditions with the addition of bulk materials are presented. It was revealed that the introduction of bulk materials increases the energy costs of clogging models up to 1.14-1.66 times. At the same time, the type of filling material affects the energy intensity of pile driving. It was also found that the resistance of pile models to static vertical loads increased up to 1.15-1.68 times when introducing bulk materials during clogging. It is shown that the type of filling material influences the resistance of pile models to the action of vertical static load.

Experimental and kinetic modeling studies on oxidation of methanol and di-tert-butyl peroxide in a jet-stirred reactor

Methanol is a potential carbon neutral fuel, but it faces the challenge of ignition difficulties in engines. Di-tert-butyl peroxide (DTBP), a cetane number improver, is considered to be added into methanol to improve ignition. However, there is currently no research of experiments and simulations on the kinetic model of methanol and DTBP. Therefore, the oxidation characteristics of methanol and DTBP were experimentally studied in a jet-stirred reactor under temperatures of 400–1000 K and pressures of 1.03 atm, with equivalence ratios of 0.5, 1 and 2 for pure methanol, pure DTBP, blended fuel (97 % CH3OH + 3 % DTBP; 94 % CH3OH + 6 % DTBP). Then, a new reduced CH3OH-DTBP mechanism containing 75 species and 443 reactions was proposed, which was widely validated by experimental data of ignition delay times, laminar flame speeds and species concentration profiles. Next, the simulations were conducted with CHEMKIN PRO to analyze the effect of DTBP on methanol. The major findings are as follows. After adding DTBP, methanol can react at a lower temperature (550 K), which is due to CH3 generated by decomposition of DTBP promotes the enrichment of OH, thereby promoting the oxidation of methanol. The source of OH at 650 K is CH3 → CH3O2 → CH3O2H → CH3O. At 850 K, the early OH comes from R27 (CH3 + HO2=CH3O + OH), while the later OH comes from the decomposition of H2O2. When the temperature is above 850 K, the addition of DTBP has only a slight effect on the oxidation of methanol. As the temperature increases, the effect of DTBP on shortening the ignition delay time weakens. As DTBP concentration increases, the effect also shows a weakening trend. At low temperatures, the contribution of thermal effects caused by DTBP is greater. As DTBP concentration increases, the proportion of thermal effect contribution increases.

Mango extract behavior as a potent corrosion inhibitor against simulated chloride-contaminated concrete pore solution; coupled experimental and computer modeling studies

Plants extracts are nominated as reliable green sources among all classes of effective materials for metals' corrosion mitigation in various aggressive media. Herein, Mango extract was announced as a potential candidate for declining the corrosion rate of mild steel in the simulated concrete pore solution (CPS). With aiding polarization and EIS tests, the mechanism and anti-corrosion performance of the inhibitor were investigated. Surface studies were also performed for studying the inhibitors' impact on the metal surface morphology after immersion in CPS. Besides, Quantum chemistry and atomistic simulations are covered to clarify the mechanism of protection on an atomic scale. The electrochemical claims represented the mixed type inhibition and slight anodic inhibition dominancy. 2 wt.% Mango extract could diminish metal corrosion rate in the harsh CPS by around 98% index. Also, molecular simulations (Monte Carlo, MC and Molecular Dynamics, MD) represented the spontaneous absorption of the complexed heavy molecules (coordination compounds of extract molecules and inorganic cations) owing to the negative adsorption energy. Additionally, the electronic-scale quantum chemistry modeling illustrated that the adsorption of complexes mainly happened through their electron-rich sites.

Zinc and aging: a narrative review of the effects on hematopoiesis and its link with diseases.

There has been a global increase in the older population in recent decades and, as age advances, complex metabolic and epigenetic changes occur in the organism, and these may trigger some health complications commonly found among this population. Additionally, several changes occur in older people that can reduce the dietary intake or the process of nutrient absorption. In this way, tissues with high nutrient requirements are more affected. Hematopoiesis is the process of formation, development, and maturation of blood cells and is a process with a high turnover. This high demand makes the integrity of the hematopoietic process susceptible to various factors that impair physiological function, such as aging and micronutrient bioavailability. Among these micronutrients, Zinc is considered an important micronutrient, playing diverse roles across various tissues and cell types. Some of the alterations in hematopoiesis that appear as a consequence of aging and due to insufficient micronutrient intake are well described in the literature; however, not much is known about how zinc deficiency contributes towards the development of diseases seen in aging. Considering the importance of zinc to act on several biological processes, this narrative review discusses several studies related to the physiological requirements, deficiency, or excess of zinc, including studies in experimental models and humans, and aimed to shed light on the relationship between zinc and the regulation of hematopoietic tissue, exploring possible links between this mineral with common disorders that appear during aging.

The Dark Side of Energy Drinks: A Comprehensive Review of Their Impact on the Human Body.

In recent years, the consumption of energy drinks by young adults and athletes has risen significantly, but concerns have been raised about the potential health risks associated with excessive consumption. These concerns include cardiovascular problems, nervous system disorders, and the potential for addiction. This review aims to examine the reported effects of acute or chronic abuse of energy drinks on human health. The analysis shows a significant prevalence of adverse effects, particularly on the cardiovascular and neurovegetative systems. In particular, the analysis identified nine cases of cardiac arrest, three of which were fatal. The aetiology of these adverse effects is attributed to the inherent neurostimulant properties of these beverages, of which caffeine is the predominant component. A comparison of documented effects in humans with experimental studies in animal models showed an overlap in results. This review highlights the need for greater rigour in the assessment of sudden cardiac death, particularly in young people, as legal substances such as energy drinks may be involved. We propose stricter limits on the consumption of these beverages than for caffeine, based on the evidence found and the data in the literature. This review also calls for the establishment of regulations governing the consumption of these products in view of their potential impact on human health.

Pentoxifylline and Vitamin E Can Restrict Radiation Necrosis via Vascular Pathways, Experimental Study in an Animal Model

Radiation necrosis (RN) is a long-term side effect of Gamma Knife stereotactic radiosurgery that may require surgical intervention. Pentoxifylline and vitamin E have previously been shown to be effective in the treatment of RN in the published literature, but there are no data on the prophylactic use of these molecules or, more importantly, whether prophylaxis is required. The iatrogenic RN model included 50 Sprague-Dawley rats of both sexes. There were 7 treatment subgroups established. Gamma-Plan 8.32 was used to plan after magnetic resonance scans were performed in a specially designed frame. The injection doses used in the treatment groups were vitamin E (30mg/kg/day in a single dose) and pentoxifylline (50mg/kg/day in 2 doses). Control magnetic resonance scans were performed at the end of a 16-week treatment, and the subjects were decapitated for pathological evaluations. The intensity of hypoxia - inducible factor 1α immunoreactivity is statistically significantly lower in the therapeutic vitamin E, prophylactic pentoxifylline and vitamin E, and therapeutic pentoxifylline and vitamin E groups than in the other groups. Similarly, the intensity of vascular endothelial growth factor immunoreactivity was reduced in the therapeutic vitamin E and prophylactic pentoxifylline and vitamin E treatment modality groups.When compared with other groups, the therapeutic pentoxifylline group had significantly fewer vascular endothelial growth factor-immunoreactive cells in the perinecrotic area, with an accompanying decreased contrast enhancement pattern. Both vitamin E and pentoxifylline are effective for the treatment and/or restriction of RN, either alone or in combination. The use of these molecules as a preventive measure did not outperform the therapeutic treatment.

Combined Experimental and Mechanoelastic Modeling Studies on the Low-Spin Stabilized Mixed Crystals of 3D Oxalate-Based Coordination Materials.

Structural studies involving single-crystal and powder X-ray diffraction analysis have been performed on dehydrated coordination networks of the [NixCo1-x(bpy)3][LiCr(ox)3] series, 0 ≤ x ≤ 1, (bpy = 2,2'-bipyridine). The high-symmetry cubic 3D structure of these materials is formed by oxalate anions bridging alternating Cr3+ and Li+ ions into an anionic framework, which contains large cavities that incorporate the [NixCo1-x(bpy)3]2+ cations. Irrespective of the Co/Ni ratio, all of the mixed samples are phase-pure and retain the high-symmetry cubic structure, with the lattice parameters gradually decreasing upon increasing Ni(II) concentration. The influence of the Ni(II) dilution on the magnetic behavior of these materials is substantial. For pure [Co(bpy)3][LiCr(ox)3], a gradual but incomplete thermal spin-crossover is evident due to the effect of the chemical pressure applied by the [LiCr(ox)3]2- framework, which stabilizes the low-spin (LS) 2E state relative to the high-spin (HS) 4T1 state of the Co(II) ion. Upon increasing the Ni(II) content, the spin-crossover becomes even more gradual and incomplete and eventually is not observed for pure [Ni(bpy)3][LiCr(ox)3]. The average spin-crossover temperature increases with the increasing Ni(II) content, suggesting a higher degree of chemical pressure applied by the oxalate framework manifested by changing the ΔE0HL toward positive values. The magnetic behavior of all these framework materials has been explained by the mechanoelastic model, considering different radii for Co and Ni molecules and different interactions between Co-Co sites and Co-Ni sites. The model reproduced the incomplete transition, with the HS residual fraction at 300 K decreasing with increasing Ni concentration, and provided microscopic snapshots of the systems, showing how the existence of impurities prevented the spreading of Co atoms in the HS state.

Experimental and numerical study of the effect of H2O and CO2 dilution on NH3/CH4 co-oxidation characteristics in a jet-stirred reactor

This work reports an experimental and kinetic modeling study of NH3/CH4 co-oxidation in O2/N2 in a jet-stirred reactor (JSR) covering a reaction temperature of 900–1450 K, equivalence ratio of 0.5–2.0, and dilution degree of 0%–30% with H2O and CO2, respectively. Experimental results show that CO formation is inhibited by H2O dilution while enhanced by CO2 dilution. NO formation is suppressed by either H2O or CO2 dilution under lean condition, however these two diluents generally would accelerate NO formation under stoichiometric and rich conditions. Dong2022 mechanism is selected for further kinetic analysis for NO conversion under stoichiometric condition. It shows that N2H2 plays a more significant role in NO generation in N2/CO2 atmosphere. The reactions of NH + OH ↔ HNO + H and NH2 + O ↔ HNO + H contribute the most for boosting NO formation under both H2O and CO2 dilution conditions.

Latanoprost incorporates in the tear film lipid layer: An experimental and computational model study

Glaucoma is a leading cause of blindness worldwide, with elevated intraocular pressure being a major risk factor for its development and progression. First-line treatment for glaucoma relies on the administration of prostaglandin analogs, with latanoprost being the most widely used. However, before latanoprost reaches the cornea, it must pass through the tear film and tear film lipid layer (TFLL) on the ocular surface. Given the significant lipophilicity of latanoprost, we hypothesize that TFLL could, to a certain extent, act as a reservoir for latanoprost, releasing it on longer time scales, apart from the fraction being directly delivered to the cornea in a post-instillation mechanism. We investigated this possibility by studying latanoprost behavior in acellular in vitro TFLL models. Furthermore, we employed in silico molecular dynamics simulations to rationalize the experimental results and obtain molecular-level insight into the latanoprost-TFLL interactions. Our experiments demonstrated that latanoprost indeed accumulates in the TFLL models, and our simulations explain the basis of the accumulation mechanism. These results support the hypothesis that TFLL can serve as a reservoir for latanoprost, facilitating its prolonged release. This finding could have significant implications for optimizing glaucoma treatment, especially in the development of new drug delivery systems targeting the TFLL.