Rich Core Research Articles

Manipulation of defect state emission in Zn chalcogenide quantum dots and their effects on chlorophyll spectral response

Water soluble Zn based quantum dots (QDs) are of interest due to their biocompatibility and less toxic features. They have been frequently used in studies related to biotechnology, especially in agriculture studies. However, to control the optical properties of Zn based QDs has still been a challenge. In this work, the defect state emission of ZnSe QDs was successfully controlled through two different routes; 1) By creating a sulfur rich outer region around the Se rich core 2) By changing the capping agent. Gradient alloyed ZnSeS QDs with Se rich core and S rich outer region were successfully synthesized with two different capping agents; N-Acetyl-L-Cysteine (NAC) and 3-Mercaptopropionic Acid (3-MPA). The contribution of emission originated from surface-defects almost disappeared in NAC capped ZnSeS QDs, with causing a significant increase in photoluminescence quantum yield. The interaction between Zn based QDs with chlorophyll molecules was also investigated. The absorption capacity of chlorophylls significantly enhanced upon interaction with 3-MPA capped ZnSeS QDs. Also, the spectral response of chlorophylls could be modulated through interaction with 3-MPA capped ZnSeS QDs, which could be manipulated by using ZnSeS QDs with different chemical composition. Our results indicated that ZnSeS QDs have potential to be used in agriculture, which could act as a modulator of light-harvesting capacity of chlorophylls. The ability to modulate chlorophyll spectral responses through QD interaction opens new possibilities for optimizing light utilization in photosynthetic organisms, thereby contributing to enhanced crop yields and more efficient use of light energy in natural and artificial ecosystems.

Diagnostic accuracy of carotid plaque magnetic resonance imaging compared to histopathology in symptomatic carotid artery stenosis

IntroductionVulnerable plaques have been shown to predict ipsilateral cerebral ischemic events and identifying them leads to appropriate secondary stroke prevention strategies. We evaluated the diagnostic accuracy of MR carotid plaque imaging in identifying plaque vulnerability when compared with histopathological findings in patients with symptomatic carotid stenosis who underwent carotid endarterectomy (CEA). MethodsA prospective cohort of forty-five consecutive patients with moderate to severe symptomatic carotid stenosis who underwent CEA at a tertiary Indian hospital had 3 T MRI plaque imaging with multi-parametric protocol between November 2021 and December 2022. Images were analyzed by a vascular radiologist blinded to histopathological data. High-risk plaque characteristics such as lipid rich necrotic core (LRNC), intraplaque hemorrhage (IPH), thin fibrous cap and ulceration were assessed and correlated with histopathological findings as per American Heart Association (AHA) classification using Cohen’s kappa statistics to obtain diagnostic accuracies. ResultsOf the 45 patients, 38(84 %) were males. The mean age was 65 ± 7.7 years and mean duration to CEA from the most recent event was 57 days (57 ± 46 days). A significant correlation between MR plaque imaging and histopathology was noted for IPH (sensitivity-91 %, specificity-86 %, κ = 0.774, p < 0.001), LRNC (sensitivity-92.1 %, specificity-85.7 %, κ = 0.697, p < 0.001), and plaque ulceration (sensitivity-84.6 %, specificity-78.1 %, κ = 0.563, p < 0.001). MRI had an overall sensitivity and specificity of 92.3 % and 84.2 % respectively (κ = 0.77, p < 0.001) in discriminating high risk plaques. ConclusionMR plaque imaging shows a very good correlation with histopathology and can identify unstable high-risk plaques with high accuracy. This may have implication in selection of patients for carotid revascularization in symptomatic carotid stenosis.

30-Day Risk Score for Mortality and Stroke in Patients with Carotid Artery Stenosis Using Artificial Intelligence Based Carotid Plaque Morphology

The gold standard for determining carotid artery stenosis intervention is based on a combination of percent stenosis and symptomatic status. Few studies have assessed plaque morphology as an additive tool for stroke prediction. Our goal was to create a predictive model and risk score for 30-day stroke and death inclusive of plaque morphology. Patients with a computed tomographic angiography head/neck between 2010 and 2021 at a single institution and a diagnosis of carotid artery stenosis were included in our analysis. Each computed tomography was used to create a three-dimensional image of carotid plaque based off image recognition software. A stepwise backward regression was used to select variables for inclusion in our prediction models. Model discrimination was assessed with area under the receiver operating characteristic curves (AUCs). Additionally, calibration was performed and the model with the least Akaike Information Criterion (AIC) was selected. The risk score was modeled from the Framingham Study. Primary outcome was mortality/stroke. We created 3 models to predict mortality/stroke from 366 patients: model A using only clinical variables, model B using only plaque morphology and model C using both clinical and plaque morphology variables. Model A used age, sex, peripheral arterial disease, hyperlipidemia, body mass index (BMI), chronic obstructive pulmonary disease (COPD), and history of transient ischemia attack (TIA)/stroke and had an AUC of 0.737 and AIC of 285.4. Model B used perivascular adipose tissue (PVAT) volume, lumen area, calcified volume, and target lesion length and had an AUC of 0.644 and AIC of 304.8. Finally, model C combined both clinical and software variables of age, sex, matrix volume, history of TIA/stroke, BMI, PVAT, lipid rich necrotic core, COPD and hyperlipidemia and had an AUC of 0.759 and an AIC of 277.6. Model C was the most predictive because it had the highest AUC and lowest AIC. Our study demonstrates that combining both clinical factors and plaque morphology creates the best predication of a patient's risk for all-cause mortality or stroke from carotid artery stenosis. Additionally, we found that for patients with even 3 points in our risk score model has a 20% chance of stroke/death. Further prospective studies are needed to validate our findings.

Mineral chemistry of chrome-diopside bearing lamprophyre from Mesoproterozoic Settupalle igneous complex of Prakasam alkaline province: insights on the magma dynamics at shallow lithospheric mantle beneath the NE margin of the Cuddapah basin, Southern India

The Eastern Dharwar Craton shows considerable variations in the activity of kimberlite, lamproite and lamprophyre and their related lithospheric thickness, thermal structure and magmatic source characteristics from the innermost core to the margin. These variations have been revealed through seismic studies and the analysis of xenoliths, and xenocrysts carried in alkaline magmas, particularly kimberlites. This study reports the occurrence of chrome-diopside phenocrysts from a lamprophyre of the Settupalle pluton, located on the northeastern margin of the Cuddapah basin, Prakasam alkaline province in South India. Studied lamprophyre are characterized by phenocrystic clinopyroxene (Cpx) and biotite, embedded in a groundmass of amphibole, biotite, opaques, calcite, feldspar, nepheline and sodalite, with the latter minerals forming ocellar structures. Clinopyroxene displays normal zoning, with a high Mg–Cr rich diopside core (up to 1.92 wt%) and a Na 2 O-, Al 2 O 3 , FeO and TiO 2 -enriched salite rim. These chemical variations, along with elemental substitutions from core to rim, indicate the significant role of fractionation in the evolution of lamprophyre magma. The lack of chemical disparity among the studied Cpx suggests closed system fractionation, under high oxygen fugacity conditions. Thermobarometry results indicate polybaric crystallization for the Cpx (1206–1269°C, 11.82–18.04 kbar) and biotite (825–856°C, 3.49–6.94 kbar). The gradient inferred from the pressure of the Cpx suggests that its crystallization occurred at a depth of 43–66 km, implying shallow lithospheric magma contribution for the genesis of the lamprophyre magma.

The Vitality of Open Source Software

Open Source Software (OSS) is a cornerstone of modern technology, embodying principles of collaboration, transparency, and accessibility. This article explores the rich history, core principles, and significant impact of open source software across various domains. From its inception in the early days of computing to its current role in shaping modern computing paradigms, we delve into the dynamics that make OSS a vibrant ecosystem. Through case studies, discussions on challenges, and prospects for the future, we highlight the enduring vitality of open source software.

Democracy in India is at Stake: Image of the Last Decade

Indian democracy is going to step its 75 years of journey. Indian democracy is still singing even after happening many ups and downs in the country and in the world. Ours is a world largest democracy. We are really, proud of it. Democracy has a long tradition and rich history in India. That means the idea that democratic ethos and principles are not new to the Indian subcontinent. Our rich democratic heritage, sets a precedent a for promoting civic culture, political participation, and a well understanding of democratic principles among its citizens. In recent, India's G20 presidency reflects its commitment to democratic values and international cooperation. The country sets an example to promote global democratic principles. The Parliament 20 (P20) Summit in New Delhi put forwards India's rich democratic heritage and core values to the world. The inclusivity, equality, and harmony are central to Indian democracy. But the scholars and theorists of Indian democracy come to realize that, the picture of our democracy of the last one decade is not so satisfactory. Democracy-watching organizations categorize democracies differently. They all classify India today as a “hybrid regime”—that is, neither a full democracy nor a full autocracy. And this is new one. In 2021, in view of Freedom House, India’s freedom rating is Partly Free (the only remaining category is Not Free). That same year, the Varieties of Democracy (V-Dem) project India as “electoral autocracy” on its scale of closed autocracy, electoral autocracy, electoral democracy, or liberal democracy. And the Economist Intelligence Unit stated India to be “flawed democracy” on its scale of full democracy, flawed democracy, hybrid regime, and authoritarian regime. Keeping all these things in mind, in this paper, I have tried to critically examine the Indian democracy of the last one decade on the basis of a small ground level study.

Tumor-activated targetable photothermal chemotherapy using IR780/zoledronic acid-containing hybrid polymeric nanoassemblies with folate modification to treat aggressive breast cancer.

To effectively treat aggressive breast cancer by tumor-activated targetable photothermal chemotherapy, in this work, folate (FA)-modified hybrid polymeric nanoassemblies (HPNs) with a poly(ethylene glycol) (PEG)-detachable capability are developed as vehicles for tumor-targeted co-delivery of IR780, a lipophilic photothermal reagent, and zoledronic acid (ZA), a hydrophilic chemotherapy drug. Through hydrophobic interaction-induced co-assembly, IR780 molecules and ZA/poly(ethylenimine) (PEI) complexes were co-encapsulated into a poly(lactic-co-glycolic acid) (PLGA)-rich core stabilized by the amphiphilic FA-modified D-α-tocopheryl poly(ethylene glycol) succinate (FA-TPGS) and acidity-sensitive PEG-benzoic imine-octadecane (C18) (PEG-b-C18) conjugates. The developed FA-ZA/IR780@HPNs with high ZA and IR780 payloads not only showed excellent colloidal stability in a serum-containing milieu, but also promoted IR780-based photostability and photothermal conversion efficiency. Furthermore, for FA-ZA/IR780@HPNs under simulated physiological conditions, the premature leakage of IR780 and ZA molecules was remarkably declined. In a mimetic acidic tumor microenvironment, the uptake of FA-ZA/IR780@HPNs by FA receptor-overexpressed 4T1 breast cancer cells was remarkably promoted by PEG detachment combined with FA receptor-mediated endocytosis, thus effectively hindering migration of cancer cells and augmenting the anticancer efficacy of photothermal chemotherapy. Notably, the in vivo studies demonstrated that the FA-ZA/IR780@HPNs largely deposited at 4T1 tumor sites and profoundly suppressed tumor growth and metastasis without severe systemic toxicity upon near infrared (NIR)-triggered IR780-mediated hyperthermia integrated with ZA chemotherapy. This work presents a practical strategy to treat aggressive breast tumors with tumor-triggered targetable photothermal chemotherapy using FA-ZA/IR780@HPNs.

Tuning the morphology and chemical distribution of Ag atoms in Au rich nanoparticles using electrochemical dealloying.

Dealloying of Ag-Au alloy nanoparticles (NPs) strongly differs from the corresponding bulk alloy materials. Here, we have investigated the effects of potentiodynamic and potentiostatic dealloying on structure and distribution of residual Ag atoms for Au rich NPs. Two different sizes of Ag rich alloy NPs, 77 ± 26 nm Ag77Au23 and 12 ± 5 nm Ag86Au14, were prepared. 77 nm Ag77Au23 NPs form a homogeneous alloy, while 12 nm Ag86Au14 NPs show an Ag rich shell-Au rich core arrangement. The two groups of as-prepared NPs were dealloyed either under potentiodynamic (0.2-1.3 VRHE) or potentiostatic (0.9, 1.2, and 1.6 VRHE) conditions in 0.1 M HClO4. For the initial 77 nm Ag77Au23 NPs, both dealloying protocols lead to pore evolution. Interestingly, instead of homogenous Ag distribution, numerous Ag rich regions form and locate near the pores and particle edges. The critical dealloying potential also differs by ∼500 mV depending on the dealloying method. The initial 12 nm Ag86Au14 NPs remain dense and solid, but Ag distribution and thickness of the Au passivation layer vary between both dealloying protocols. When the Au passivation layer is very thin, the residual Ag atoms tend to segregate to the particle surface after dealloying. Due to the size effect, small NPs are less electrochemically stable and show a lower critical dealloying potential. In this systematic study, we demonstrate that the mobility of Au surface atoms and dealloying conditions control the structure and residual Ag distribution within dealloyed NPs.

Probing the Behavior of Composition‐Tunable Ultrathin PtNi Nanowires for CO Oxidation and Small‐Molecule Electrocatalytic Reactions

AbstractWe have successfully synthesized ultrathin nanowires of pure Pt, Pt99Ni1, Pt9Ni1, and Pt7Ni3 using a modified room‐temperature soft‐template method. Analysis of both methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) results found that the Pt7Ni3 samples yielded the best performance with specific activities of 0.36 and 0.34 mA/cm2 respectively. Additionally, formic acid oxidation reaction (FAOR) tests noted that both Pt and PtNi nanowires oxidize small organic molecules (SOMs) via an indirect pathway. CO oxidation data suggests little measurable performance without any pre‐reduction treatment; however, after annealing in H2, we detected significantly improved CO2 formation for both Pt9Ni1 and Pt7Ni3 motifs. These observations highlight the importance of pre‐treating these nanowires under a reducing atmosphere to enhance their performance for CO oxidation. To explain these findings, we collected extended x‐ray adsorption fine structure (EXAFS) spectroscopy data, consistent with the presence of partial alloying with a tendency for Pt and Ni to segregate, thereby implying the formation of a Pt‐rich shell coupled with a Ni‐rich core. We also observed that the degree of alloying within the nanowires increased after annealing in a reducing atmosphere, a finding deduced through analysis of the coordination numbers and calculations of Cowley's short range order parameters.

Influence of wall shear and structural stress on plaque progression of different phenotype in human coronary arteries

Abstract Introduction Atherosclerotic plaque progression is affected by local wall shear stress (WSS), .i.e. the frictional force of the blood at the vessel wall [1,2]. However, the blood pressure also induces stress inside the vessel wall (wall stress, WMS) and is mainly studied for plaque rupture [3]. Little is known on the impact of WMS on plaque progression. Purpose In order to have a comprehensive understanding of the involvement of the biomechanical factors (WSS and WMS) in atherosclerotic artery disease, we studied the individual and combined effects of WMS and WSS in plaque free as well as in atherosclerotic coronary segments. Methods Forty non-stented, non-culprit human coronary arteries (IMPACT study) were imaged with near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) and optical coherence tomography (OCT) at the baseline and after 12 months [3]. The 2D and 3D lumen, vessel wall and lipid-rich necrotic core (LRNC) geometries were reconstructed based on the co-registration of NIRS-IVUS and OCT. WSS was computed with Computational Fluid Dynamics [3]. The WMS on the peri-luminal region was calculated via ABAQUS with hyperelastic material models [4] using intraluminal pressure of 120mmHg. The vessels were divided into 1.5mm/45° sectors. In each sector wall growth was quantified as plaque burden (plaque area/total vessel area*100%) change over time. Plaque was defined as wall thickness &amp;gt; 0.5 mm. The sectors were categorized as "plaque with lipid rich necrotic core (LRNC)", "plaque w/o lipid rich necrotic core (LRNC)", or "plaque free wall". The individual and combined effect of WSS and WMS on plaque progression was evaluated using Linear Mixed Model in SPSS and all stress metrics were divided into artery-based tertiles. Results Vessel sectors exposed to low WSS at baseline demonstrated a higher plaque burden increase over the follow up period compared to the vessel sectors exposed to mid or high WSS (Fig.1), which was significantly different for all the 3 categories (Plaque free wall, Plaque without LRNC, Plaque with LRNC). Vessel sectors exposed to increasing WMS demonstrated increasing plaque progression (Fig.1) Sectors that were simultaneously exposed to low WSS and high WMS revealed the highest change in plaque size and in particular in plaque sectors that were lipid rich (Fig.2). Conclusion Our findings suggest that the local atherosclerotic disease progression in coronary arteries is not only associated with the well-known WSS, but also with WMS. Moreover, our results show that there is an complex interplay between WSS, WMS and plaque composition, such that lipid rich plaques exposed to low WSS and high WMS demonstrated the highest plaque progression.Figure 1Figure 2

Abstract 17381: Relationship Between Amaurosis Fugax and Intraplaque Hemorrhage in Patient With Carotid Plaques

Introduction: The term amaurosis fugax is often used interchangeably to describe transient visual loss. However, it is employed widely in medicine to refer to any cause of transient monocular visual loss. Amaurosis fugax is associated with an imminent stroke and it could be linked to vascular thromboembolic events arising from the internal carotid arterial system. The aims of the study are to determine the plaque characteristics of patients who underwent carotid artery revascularization and the relationship of plaque characteristics with amaurosis fugax. Methods: Before elective carotid revascularization 44 patients (mean age 72±8 years; 25 males, 19 females) underwent 3-T MRI. After localization of the carotid bifurcation using phase contrast imaging, Time-of-Flight, 3D T1 weighting, transverse T1 and T2 weightings and proton density sequences were acquired. The different plaque components: lipid rich core, intraplaque hemorrhage, calcification and the characterization of the fibrous cap were assessed. Results: Carotid plaque samples had the following characteristics: Intraplaque hemorrhage (59%), surface defects (38.6%), stable fibrous cap (27.3%), lipid rich necrotic core (18%), and calcifications (11.4%). Amaurosis fugax history was identified in 7 patients (15.9%). Plaque samples from all 7 patients who had experienced amaurosis fugax revealed intraplaque hemorrhage. MRI revealed intraplaque hemorrhage in 19 (51%) patients without history of amaurosis fugax (p=0.016). The rest of the plaque characteristics did not show any statistically significant relationship with history of amaurosis fugax. Conclusions: This study demonstrated that intraplaque hemorrhage may be correlated to amaurosis fugax.

Development of a sustained release implant of benzathine penicillin G for secondary prophylaxis of rheumatic heart disease

BackgroundRegular intramuscular (i.m.) benzathine penicillin G (BPG) injections have been the cornerstone of rheumatic heart disease (RHD) secondary prophylaxis since the 1950s. Patient adherence to IM BPG is poor, largely due to pain, the need for regular injections every 3–4 weeks and health sector delivery challenges in resource-limited settings. There is an urgent need for new approaches for secondary prophylaxis, such as an implant which could provide sustained penicillin concentrations for more than 6 months. MethodsIn this study we developed and evaluated a slow release implant with potential for substantially extended treatment. The side wall of a solid drug rich core was coated with polycaprolactone which acts as an impermeable barrier. The exposed surfaces at the ends of the implant defined the release surface area, and the in vitro release rate of drug was proportional to the exposed surface area across implants of differing diameter. The in vivo pharmacokinetics and tolerability of the implants were evaluated in a sheep model over 9 weeks after subcutaneous implantation. ResultsThe absolute release rates obtained for the poorly water-soluble benzathine salt were dependent on the exposed surface area demonstrating the impermeability of the wall of the implant. The implants were well-tolerated after subcutaneous implantation in a sheep model, without adverse effects at the implantation site. Gross structural integrity was maintained over the course of the study, with erosion limited to the dual-exposed ends. Steady release of penicillin G was observed over the 9 weeks and resulted in approximately constant plasma concentrations close to accepted target concentrations. ConclusionIn principle, a long acting BPG implant is feasible as an alternative to i.m. injections for secondary prophylaxis of RHD. However, large implant size is currently a significant impediment to clinical utility and acceptability.

Covering All the Bases: Type-Based Verification of Test Input Generators

Test input generators are an important part of property-based testing (PBT) frameworks. Because PBT is intended to test deep semantic and structural properties of a program, the outputs produced by these generators can be complex data structures, constrained to satisfy properties the developer believes is most relevant to testing the function of interest. An important feature expected of these generators is that they be capable of producing all acceptable elements that satisfy the function’s input type and generator-provided constraints. However, it is not readily apparent how we might validate whether a particular generator’s output satisfies this coverage requirement. Typically, developers must rely on manual inspection and post-mortem analysis of test runs to determine if the generator is providing sufficient coverage; these approaches are error-prone and difficult to scale as generators become more complex. To address this important concern, we present a new refinement type-based verification procedure for validating the coverage provided by input test generators, based on a novel interpretation of types that embeds “ must -style” underapproximate reasoning principles as a fundamental part of the type system. The types associated with expressions now capture the set of values guaranteed to be produced by the expression, rather than the typical formulation that uses types to represent the set of values an expression may produce. Beyond formalizing the notion of coverage types in the context of a rich core language with higher-order procedures and inductive datatypes, we also present a detailed evaluation study to justify the utility of our ideas.

From AuPd Nanoparticle Alloys towards Core‐Shell Motifs with Enhanced Alcohol Oxidation Activity

AbstractThe best activity of bimetallic AuPd nanoparticles for alcohol oxidation reaction is usually achieved by adjusting the Au/Pd molar ratio. Herein, alloy AuPd nanoparticles of ∼2.5–3.5 nm, ranging from Au‐rich to Pd‐rich compositions, were synthesized through a sol‐immobilization method. A calcination step under air conditions caused an increase in size up to 5.5 nm, but also driven the segregation of Pd to the surface, which generated an Au rich core with Pd on the shell. At high Pd content, the shell structure is formed by PdO. The catalytic activity of Pd‐rich samples (1 : 1, 1 : 2 and 1 : 4 Au : Pd) for benzyl alcohol oxidation increased ∼4‐fold after calcination. Upon reduction with H2, surface PdO motifs are reduced to Pd that did not dissolve back into the AuPd alloy core, maintaining the metallic Pd shell. The catalytic activity decreased. Therefore, restructuring alloyed AuPd nanoparticles into core‐shell like structures with PdO in the shell is beneficial to the catalytic activity, but reduction of PdO layer was detrimental. These results provide new insights on the optimization of AuPd catalysts, considering not only the Au/Pd molar ratio, but also the importance of PdO, which was not anticipated in the previous literature.

Detection of complex nitrogen-bearing molecule ethyl cyanide towards the hot molecular core G10.47 + 0.03

The studies of the complex organic molecular lines towards the hot molecular cores at millimeter and submillimeter wavelengths provide instructive knowledge about the chemical complexity in the interstellar medium (ISM). We present the detection of the rotational emission lines of the complex nitrogen-bearing molecule ethyl cyanide (C2H5CN) towards the chemically rich hot molecular core G10.47 + 0.03 using the Atacama Large Millimeter/Submillimeter Array (ALMA) band 4 observations. The estimated column density of C2H5CN towards the G10.47 + 0.03 is (7.7 ± 0.5) × $10^{16}\text{ cm}^{-2}$ with the high rotational temperature of 352.9 ± 66.8 K. The estimated fractional abundance of C2H5CN with respect to H2 towards the G10.47 + 0.03 is 5.70 × $10^{-9}$ . We observe that the estimated fractional abundance of C2H5CN is similar to the existing three-phase warm-up chemical modelling abundance of C2H5CN. We also discuss the possible formation mechanism of C2H5CN towards the hot molecular cores, and we claim the barrierless and exothermic radical-radical reaction between CH2 and CH2CN is responsible for the production of low abundance of C2H5CN ( ${\sim} 10^{-9}$ ) in the grain surface of G10.47 + 0.03.

Leaner lifted-flame combustion with ducted fuel injection: The key role of forced two-stage mixing

Ducted fuel injection (DFI) is a new approach to realize low-soot combustion for mixing-controlled ignition engines, while the underlying physics still remains inadequately understood. In this work, a high-fidelity LES of the combustion process with DFI was performed under engine-relevant conditions, with a particular interest in understanding the formation of the leaner lifted-flame combustion. Results show that, compared to free spray, both the ignition delay time and the quasi-steady flame lift-off length of DFI are prolonged, while the relative flame lift-off length from the duct outlet is shortened. The ignition process of DFI is typically two-staged in the mixture fraction space, which is fundamentally determined by the duct-forced, two-stage mixing process in the physical space. The mean soot volume fraction is synergistically controlled by the mixture fraction and the dissipation rate at the duct outlet and shows a nonmonotonic variation of “decrease-increase” with increasing duct length. To achieve leaner lifted-flame combustion, the duct outlet should pursue a balance between a globally rich (to avoid pre-ignition in the duct), spatially uniform (to avoid an excessively rich spray core) mixture and a certain large scalar dissipation rate (to extend the flame lift-off length). Compared to the conventional rich lifted flame of free spray, the leaner lifted flame structure of DFI exhibits a broader high-temperature-induced mode region, and the low-temperature flame is no longer circumferentially surrounded by the high-temperature flame. The decrease of the peak mixture fraction in the quasi-steady flame avoids soot formation especially under high-dissipation-rate conditions, and a conceptual model is presented to describe key features of DFI.

A novel single sensor hemoglobin domain from the thermophilic cyanobacteria Thermosynechococcus elongatus BP-1 exhibits higher pH but lower thermal stability compared to globins from mesophilic organisms

Thermosynechococcus elongatus-BP1 belongs to the class of photoautotrophic cyanobacterial organisms. The presence of chlorophyll a, carotenoids, and phycocyanobilin are the characteristics that categorize T. elongatus as a photosynthetic organism. Here, we report the structural and spectroscopic characteristics of a novel hemoglobin (Hb) Synel Hb from T.elongatus, synonymous with Thermosynechococcus vestitus BP-1. The X-ray crystal structure (2.15 Å) of Synel Hb suggests the presence of a globin domain with a pre-A helix similar to the sensor domain (S) family of Hbs. The rich hydrophobic core accommodates heme in a penta-coordinated state and readily binds an extraneous ligand (imidazole). The absorption and circular dichroic spectral analysis of Synel Hb reiterated that the heme is in FeIII+ state with a predominantly α-helical structure similar to myoglobin. Synel Hb displays higher resistance to structural perturbations induced via external stresses like pH and guanidium hydrochloride, which is comparable to Synechocystis Hb. However, Synel Hb exhibited lower thermal stability compared to mesophilic hemoglobins. Overall, the data is suggestive of the structural sturdiness of Synel Hb, which probably corroborates its origin in extreme thermophilic conditions. The stable globin provides scope for further investigation and may lead to new insights with possibilities for engineering stability in hemoglobin-based oxygen carriers.

In Situ LA-ICP-MS of Zoned Garnets from the Huanggang Skarn Iron–Tin Polymetallic Deposit, Southeastern Mongolia, Northern China

The Huanggang deposit is the most important and largest skarn Fe–Sn polymetallic deposit in the Southern Great Xing’an Range of Northeast China. Cassiterite, magnetite, and other metal minerals are related to the garnets within skarn systems. The zoned garnets from various skarn stages are able to record numerous geological and mineralizing processes including variations in physicochemical conditions and hydrothermal fluid evolution. In this contribution, we present the mineralogy, systematic major, trace, and rare earth element (REE) concentrations of zoned garnets from the Huanggang Fe–Sn polymetallic skarn deposit. The in situ analytical results of garnets in the prograde skarn stage from andradite core (Grt I) to grossular rim (Grt II) reveal that core sections were formed from a fluid that was generally LREE-rich, with relatively high ∑REE, high LREE/HREE ratios, and weak negative Eu anomalies, whereas rim sections were crystallized from a fluid that was typically HREE-rich, with relatively low ∑REE, low LREE/HREE ratios, and obviously negative Eu anomalies. The garnets of the retrograde skarn stage from Fe3+-rich andradite core (Grt III) to andradite rim (Grt IV) demonstrate that the core sections have a flat trend with high ∑REE and obvious negative Eu anomalies, whereas rim sections were formed from a fluid with relatively low ∑REE, HREE-rich and obviously negative Eu anomalies. The garnets from the prograde skarn stage principally display relatively lower U and higher Y and F concentrations than those from the retrograde skarn stage. Based on optical and textural characteristics, REE patterns, Eu anomalies, and trace element variations in zoned garnets, it can be shown that, during skarn formation, Huanggang hydrothermal fluids shifted from near-neutral pH, oxidizing conditions, and high W/R ratios with relatively low LREE/HREE ratios characteristics to acidic, reducing conditions, and low W/R ratios with relatively high LREE/HREE ratios characteristics. We infer that variations in fluid compositions and physicochemical conditions may exert major control on formation and evolution of garnets and skarn hydrothermal fluids.

Soot structure and flow characteristics in turbulent non-premixed methane flames stabilised on a bluff-body

The soot properties of methane in turbulent regimes are not well characterised but are highly desirable. Methane is the main constituent of natural gas that is broadly used in many industrial combustors. Investigation of turbulent methane flames under well-defined boundary conditions is therefore useful for interpreting soot formation in practical burners and can be used for further model development. This study presents a joint experimental and numerical study of a series of turbulent non-premixed bluff-body flames fuelled with pure methane for three values of the momentum flux ratio of fuel jet to co-flowing air. Soot volume fraction (SVF) and flowfield are measured simultaneously using planar laser-induced incandescence (P-LII) and 2D-polarised particle image velocimetry (P-PIV). Additionally, time-averaged temperature, mixture fraction, OH and C2H2 concentrations are estimated numerically using RANS models. The global flame structure for all three flames features a recirculation zone with a double-vortex structure, a jet-propagating zone, and a neck zone connecting the two regions. The soot distribution within the recirculation zone shows clear distinct features, which is attributed to the mean mixture fraction distribution in this zone. Increasing the momentum flux ratio shifts the location of the mean stoichiometric mixture fraction to the rich inner vortex core, leading to a distinct peak of the total integrated soot in the inner vortex of the recirculation zone that is not observed in other cases. Also, it is deduced that the soot inception starts earlier in the recirculation zone for the flame with the highest momentum flux ratio and in the jet zone for the other two flames. Much higher soot concentration and lower intermittency are found with ethylene-based flames stabilised on the same burner and with the same operating conditions. In addition, the study has generated a database of soot and flowfield results, which can be helpful for future model validations.

Strengthening soft poly(vinyl chloride) plastics via three-arm star copolymeric plasticizers

Besides the good flexibility and extensibility, plasticized soft poly(vinyl chloride) (PVC) possessing the extra characteristics of high modulus, tensile strength and toughness are desired for wider applications. Herein, a series of three-arm star copolymers possessing the hard polylactide (PLA)-rich core and the soft poly(ε-caprolactone)-rich (PCL) shell (S3-PLA-PCL) were prepared, which were used as the plasticizers for the preparation of soft PVCs. The monomer ratio of ε-caprolactone to lactide (LA), the average polymerization degree of LA and the type of LA (racemic or L type) were optimized to achieve the best mechanical performance of soft PVCs. With the similar elongation at break, S3-PLA-PCL plasticized PVC exhibited higher modulus, strength and toughness than PVCs plasticized by the corresponding linear PLA-PCL and other traditional low molar-mass and polymeric plasticizers without hard core. This pointed out the importance of the star topology and the hard PLA-rich core of S3-PLA-PCL in strengthening soft PVCs. The transparency of PVC plasticized by S3-PLA-PCL was similar to the neat PVC and PVCs plasticized by the traditional plasticizers. Migration stability tests demonstrated that S3-PLA-PCL had excellent migration resistance in PVC matrix. Moreover, both PLA and PCL are sustainable, biocompatible and biodegradable, hence, the as-prepared S3-PLA-PCLs can be called as high-performance, green polymeric plasticizers for PVC plastics.