Oxygen Emission Research Articles

NIR light-triggered photodynamic antibacterial nanofiber membrane based on polycaprolactone and phthalocyanine derivative for biomedical applications.

Photodynamic therapy (PDT) is gaining recognition as a promising alternative method for the treatment of diverse biomedical applications. Toward this goal, we report herein the fabrication of an electrospun membrane utilizing polycaprolactone (PCL), and a phthalocyanine derivative, namely 1,4,8,11,15,22,25-octabutyloxy-29H,31-phthalocyanine (OBuPc). The designed OBuPc-PCL membrane aims to function as a dressing with the potential to facilitate the management of wound healing. The absorption and fluorescence studies of OBuPc have been examined by the steady-state and time-resolved absorption and fluorescence techniques. From direct detection of the weak emission of the singlet oxygen in the NIR region (at 1270 nm), the quantum yield of singlet oxygen was determined to be 0.05. The physiochemical properties of the nanofibers and membranes that were prepared were determined. The photo-activity of all the modified PCL nanofibers against Gram-positive S. aureus and Gram-negative E. coli was observed. The PCL/4.8 OBuPc nanofiber exhibited the highest effectiveness, primarily attributed to the enhanced effect of photosensitizer OBuPc as its concentration increased within the fibre. This resulted in S. aureus bacterial inhibition% of 62.5% ± 0.38 and 78.5% ± 0.49 after exposure to near infrared emission NIR at 630 nm for 15 minutes and 30 minutes, respectively. The inhibition of E. coli bacteria was observed to be 51.51% ± 0.49 and 62.44% ± 0.12% after exposure to near infrared (NIR) emission at a wavelength of 630 nm for durations of 15 minutes and 30 minutes, respectively. Additionally, it was observed that the membranes displayed dark bacterial inhibition. These unique features of the examined nanofibers render them a potential photodynamic antibacterial nanofiber membrane for efficient wound healing treatment and practical antibacterial uses.

The Investigation Of Performance And Emission Characteristics Of Waste Transmission Oil On A Diesel Engine

Environmental issues such as ever-increasing energy demand, declining fossil fuel deposits, global warming and higher levels of air pollution necessitate the transition to renewable fuels. It is necessary to develop a cleaner, safer, sustainable and renewable alternative for fossil fuels. For the production of such fuels using thermochemical processes, it is important to use products with a fuel potential in a waste state. In this context, it is proposed to convert waste transmission oil. Accordingly, in the study, diesel fuel was produced from waste transmission oil by pyrolysis method. The fuel produced is a mixture of diesel with waste transmission oil, 80% diesel and 20% waste transmission oil. Engine tests were carried out with the use of the produced mixture fuel and pure diesel fuel in a diesel generator engine and the necessary comparisons were carried out. In the study, emission tests were performed. In the scope of emission tests, the changes of carbon monoxide (CO), carbon dioxide (CO2), hydrocarbons (HC), nitrogen oxides (NOX) and Oxygen (O2) emissions depending on the engine load were investigated. Finally, in order to determine the performance parameters of the fuels, tests were performed for three different parameters. These tests are listed as fuel consumption, specific fuel consumption and effective efficiency measurement and calculation. According to the test results obtained, it can be said that the waste transmission oil-doped mixture fuel produced can be used instead of diesel fuel for its intended purpose.

PSXII-25 Examining Relationships Between Residual Feed Intake Classification, Enteric Emissions, and Apparent Total Tract Digestibility in Yearling Beef Heifers

Abstract Improving feed efficiency in beef heifers may help reduce enteric emissions and improve economic returns for producers. The objective of this project is to assess the relationship between traditional residual feed intake (RFI) efficiency classification, enteric gas emissions, and apparent total tract nutrient digestibility in growing yearling heifers. Angus crossbred heifers (n = 74, BW = 408 ±27.1 kg) were blocked by BW and randomly assigned to pen groups. All heifers were fed a common haylage-based diet for ad libitum intake. Insentec feeding stations (Insentec B.V., Marknesse, The Netherlands) were used to measure individual feed intake and feeding behavior data. To measure enteric gas emissions of methane (CH4), carbon dioxide (CO2), and oxygen (O2), heifer groups were rotated through pens with GreenFeed trailers (C-Lock Inc., Rapid City, SD, USA) weekly. Apparent total tract digestibility was determined by collecting fecal samples from each heifer every 9 h over three days, composited and dried at 65 °C for 96 h, and analyzed for nutrient values (A&L Canada Laboratories, London, ON, Canada). Nutrient digestibility was determined for each heifer using acid-insoluble ash (AIA) and undigestible neutral detergent fiber (uNDF) as internal markers. RFI was determined using a regression of midpoint BW and ADG and then heifers were ranked by RFI quartile group. Data were analyzed using PROC GLIMMIX in SAS, with efficiency quartile group as the fixed effect and pen as a random effect, comparisons between quartile groups were assessed with a Tukey test. As expected, efficient (least RFI) heifers had decreased dry matter intake (8.5 vs 10.1 ± 0.20 kg/d, P < 0.01), less bunk visits (70 vs 112 ± 6 visits/day, P < 0.01), spent greater time per visit (2.46 vs 1.31 ± 0.249 min/visit, P < 0.01), and consumed more feed per visit (145 vs 104 ± 11.9 g DM/visit, P < 0.03), which resulted in a faster eating rate (65 vs 98 ± 5.0 g DM/min, P < 0.01), and produced decreased enteric CO2 emissions (7,653 vs 8,120 ±122.6 g/d, P = 0.05) compared with inefficient (greatest RFI) heifers. Additionally, when using AIA as the internal marker, efficient heifers showed greater digestibility of organic matter (89.8 vs 91.4 ± 0.49 %, P = 0.02) and NDF (20.2 vs 30.0 ± 2.66 %, P = 0.04) apparent total tract digestibility, while using uNDF as the internal marker showed no difference (P > 0.20) between efficiency groups. These data indicate that more efficient yearling heifers consume less feed, have reduced enteric gas emissions, and have improved organic matter and NDF apparent total tract digestibility.

PSXII-24 Examining Relationships Between Residual Feed Intake Classification, Enteric Emissions, and Apparent Total Tract Digestibility in Late Gestation Beef Heifers

Abstract Improving feed efficiency on forage-based systems can be an important tool for beef producers to reduce their environmental footprint. The objective of this project is to assess the relationship between traditional residual feed intake (RFI) efficiency classification, enteric gas emissions, and apparent total tract nutrient digestibility in late gestation beef heifers. Pregnant Angus crossbred heifers in late gestation (n = 72, BW = 576 ± 45.8 kg) were blocked by expected calving date and randomly assigned to pen groups. Heifers had ad libitum access to a common haylage-based diet formulated to meet nutritional requirements for the last eight weeks of gestation. Individual feed intake and behavior data were recorded daily using Insentec feeding stations (Insentec B.V., Marknesse, The Netherlands). Groups of heifers were rotated through pens with access to GreenFeed trailers (C-Lock Inc., Rapid City, SD, USA) to measure enteric gas emissions of methane (CH4), carbon dioxide (CO2), and oxygen (O2). To determine individual apparent total tract digestibility, fecal samples were collected from each heifer every 9 h over three days, mixed, dried at 65 °C for 96 h, and analyzed for nutrient values (A&L Canada Laboratories, London, ON, Canada). Nutrient digestibility was determined for each heifer using acid-insoluble ash (AIA) and undigestible neutral detergent fiber (uNDF) as internal markers. Heifer RFI was determined using predicted DM intake as a regression of midpoint BW and ADG, and heifers were classified by RFI quartile group. Data were analyzed using PROC GLIMMIX in SAS, with efficiency quartile group as the fixed effect and pen as a random effect, comparisons between quartile groups were assessed with a Tukey test. Heifers classified as efficient (lowest RFI) had decreased DMI (8.2 vs 10.7 ± 0.21 kg/d, P < 0.01), less bunk visits (43 vs 64 ± 5 visits/day, P < 0.01) and greater time per visit (4.8 vs 3.0 ± 0.53 min/visit, P = 0.05). Efficient heifers also had reduced CH4 (219 vs 245 ± 6.2 g/d, P = 0.03) and CO2 (7,517 vs 8,074 ± 165.9 g/d, P = 0.01) emissions compared with inefficient (greatest RFI) heifers. However, apparent total tract digestibility of organic matter, crude protein, NDF, ADF, starch, and sugar using AIA (P > 0.08) or uNDF (P > 0.06) as internal markers were not correlated with heifer efficiency. These data indicate that more efficient heifers in late gestation consume less feed and have reduced enteric emissions, despite no differences in apparent total tract digestibility.

Screening Ba0.9A0.1MnO3 and Ba0.9A0.1Mn0.7Cu0.3O3 (A = Mg, Ca, Sr, Ce, La) Sol-Gel Synthesised Perovskites as GPF Catalysts.

Ba0.9A0.1MnO3 (BM-A) and Ba0.9A0.1Mn0.7Cu0.3O3 (BMC-A) (A = Mg, Ca, Sr, Ce, La) perovskite-type mixed oxides were synthesised, characterised, and used for soot oxidation in simulated Gasoline Direct Injection (GDI) engine exhaust conditions. The samples have been obtained by the sol-gel method in an aqueous medium and deeply characterised. The characterization results indicate that the partial substitution of Ba by A metal in BaMnO3 (BM) and BaMn0.7Cu0.3O3 (BMC) perovskites: (i) favours the hexagonal structure of perovskite; (ii) improves the reducibility and the oxygen desorption during Temperature-Programmed Desorption (O2-TPD) tests and, consequently, the oxygen mobility; (iii) mantains the amount of oxygen vacancies and of Mn(IV) and Mn(III) oxidation states, being Mn(IV) the main one; and (iv) for Ba0.9A0.1Mn0.7Cu0.3O3 (BMC-A) series, copper is partially incorporated into the structure. The soot conversion data reveal that Ba0.9La0.1Mn0.7Cu0.3O3 (BMC-La) is the most active catalyst in an inert (100% He) reaction atmosphere, as it presents the highest amount of copper on the surface, and that Ba0.9Ce0.1MnO3 (BM-Ce) is the best one if a low amount of O2 (1% O2 in He) is present, as it combines the highest emission of oxygen with the good redox properties of Ce(IV)/Ce(III) and Mn(IV)/Mn(III) pairs.

Oxygen Demand Forecasting and Optimal Scheduling of the Oxygen Gas Systems in Iron- and Steel-Making Enterprises

Due to the imbalance between the supply and demand of oxygen, the oxygen systems of iron- and steel-making enterprises in China have problems with high oxygen emissions and high pressure in the pipelines, resulting in the energy consumption of oxygen production being high. To reduce the energy consumption of oxygen systems, this study took a large-scale iron- and steel-making enterprise as a case study and developed a two-stage forecasting and scheduling model. The novel aspect and progressiveness of this work are as follows: First, an oxygen demand forecasting model was developed based on the backpropagation neural network with genetic algorithm optimization (GABP) and is driven only by historical data. Compared with some complex models in the literature, although the accuracy of this model has been reduced, the model does not need to consider production plans for other process steps, making it more practical and feasible. Second, different from the existing literature, an oxygen production scheduling model was developed for load-variable ASUs with an internal compression process, and both the oxygen emissions and pipeline pressure are included in the objective function. The case study showed that based on the oxygen demand forecast and optimal scheduling, the oxygen emissions and pipeline pressure in the studied iron- and steel-making enterprise can be significantly reduced, thereby achieving considerable energy-saving effects and economic benefits. Specifically, the following conclusions were obtained: (1) For the oxygen demand forecast, the prediction accuracy of the GABP model was better than that of the ARIMA model. The average MAPE of the 12 sets of data of the ARIMA and GABP models was 23.8% and 20.2%, respectively. (2) By comparing the scheduling results and the field data, it was found that after scheduling, the amount of oxygen emissions decreased by 6.32%, the pipeline pressure decreased by 0.61%, and the energy consumption of oxygen compression decreased by 1.6%. Considering both the oxygen emission loss and the energy consumption of oxygen compression, the total power consumption of the studied oxygen system was reduced by 1.38%, resulting in electricity cost savings of approximately 9.03 million RMB per year.

Imidazolium-Based Heavy-Atom-Free Photosensitizer for Nucleus-Targeted Fluorescence Bioimaging and Photodynamic Therapy.

The development of heavy-atom-free photosensitizers (PSs) for photodynamic therapy (PDT) has encountered significant challenges in achieving simultaneous high fluorescence emission and reactive oxygen species (ROS) generation. Moreover, the limited water solubility of these PSs imposes further limitations on their biomedical applications. To overcome these obstacles, this study presents a molecular design strategy employing hydrophilic heavy-atom-free PSs based on imidazolium salts. The photophysical properties of these PSs were comprehensively investigated through a combination of experimental and theoretical analyses. Notably, among the synthesized PSs, the ethylcarbazole-naphthoimidazolium (NI-Cz) conjugate exhibited efficient fluorescence emission (ΦF = 0.22) and generation of singlet oxygen (ΦΔ = 0.49), even in highly aqueous environments. The performance of NI-Cz was validated through its application in fluorescence bioimaging and PDT treatment in HeLa cells. Furthermore, NI-Cz holds promise for two-photon excitation and type I ROS generation, nucleus localization, and selective activity against Gram-positive bacteria, thereby expanding its scope for the design of heavy-atom-free PSs and phototheranostic applications.

Biotechnical approach for a continuous simultaneous increase of indoor and outdoor air quality

Phytofiltration is the most sustainable way to achieve a better quality of inlet air in buildings in a polluted environment. But they don’t take into account the biorhythms of plants and pollute the inlet air with CO2 during breathing only time. We collected and analysed data about the biorhythms of plants. As a result, a new bi-directional phytofilter was offered for cleaning and oxygenation of the inlet ventilation air, and also to protect the environment by cleaning the exhaust air from different pollutants. The device has spaces with shifted illumination rhythms and a valve system. A controller directs the inlet air to the space(s), where plants release CO2. The outlet air runs through other spaces. Literature data show that in the less favourable case, the CO2 and oxygen emissions are balanced per day without overall CO2 gain to the environment. When plants are growing, they sequestrate CO2 to catch greenhouse gas emissions. Either natural light, artificial light, or a combination of the two can be used. While the second option simply demands one plant metabolism type, the first option needs a combination of CAM metabolism and other plants

THE INFLUENCE OF INTAKE VALVE CLOSE TIMING ON THE ENVIRONMENTAL PERFORMANCE OF A SPARK IGNITION ENGINE USING GASOLINE AND NATURAL GAS

The tightening of environmental requirements has forced car manufacturers to look for various ways to reduce exhaust gas emissions. The existing structural solutions of internal combustion engines allow this type of pollution to be reduced by adjusting the intake valve timing. This is especially relevant when it comes to reducing spark ignition engine emissions when using natural gas as fuel. In this study, a wide range of intake valve timing adjustments from 24° to 54° every six crank angle degrees was taken at a constant engine speed (n = 2500 rpm) and different loads and fixed excess air ratios (λ = 1). The changes in oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), nitrous oxide (NOx), methane (CH4), and propane (C3H8) gas emissions were observed in the aforementioned intake valve timing range.

Investigation of the effect of advance angle on performance and emissions (exhaust, vibration, noise) in a single‐cylinder diesel engine whose fuel system is converted to common rail

AbstractIn diesel engines, the most important parameter affecting the combustion performance is the injection advance. Since the injection advance directly affects the combustion quality, it also directly affects the outputs, such as ignition delay, in‐cylinder pressure, fuel consumption, and emission values. Therefore, setting the advance angle correctly is exceedingly significant for the optimum operation of the engine in all conditions. In this study, a single‐cylinder diesel engine with a mechanical fuel system was converted to a common rail fuel system by revising its fuel system. Experiments were carried out with the converted engine at a constant speed (1850 rpm), at different loads (3–4.5–6–7.5–9 Nm), and at different advance angles (10, 12, 14, 16, 18°). In the experiments, engine performance and emission (exhaust, vibration, noise) data were examined. When the cylinder pressure data is evaluated, the maximum in‐cylinder pressure approaches the top dead point in parallel with the increase in the advance angle. Specific fuel consumption occurred at a minimum advance angle of 10° under all load conditions. In exhaust emissions, minimum values at 10° advance angle were obtained for all emissions except for oxygen emissions. Vibration emissions were reduced by 6% at a 10° advancing angle compared to 18° advancing angle at 3 Nm load. It was determined that noise emissions decreased by 1.76% in the same experimental parameters. When all data are evaluated, the optimum advance angle for the revised fuel system has been determined as 10°.

Two-stage distributionally robust integrated scheduling of oxygen distribution and steelmaking-continuous casting in steel enterprises

In the steel industry, the imbalance between fluctuating oxygen demand and stable supply generally results in excessive oxygen emissions and power waste. Independent optimal scheduling of oxygen distribution (OD) or steelmaking-continuous casting (SCC) has limited ability to handle this issue. To address this challenge, we propose an integrated scheduling model that allows for flexible interaction between OD and SCC. We first develop an SCC scheduling model that applies to machine sharing of duplex and conventional smelting, and derive an OD scheduling model. A critical demand interface is further designed to connect the scheduling models of SCC and OD, resulting in a mixed integer linear programming-based integrated scheduling model. Existing research overlooks the probability information of demand uncertainty posed by unpredictable interferences, which limits the ability to handle uncertain demands. To address this limitation, we embed demand probability distribution via a data-driven ambiguity set and upgrade the deterministic integrated scheduling model via two-stage distributionally robust optimization. Our model was tested with real data and resulted in a 15% reduction in total costs compared to independent scheduling of OD and SCC. Additionally, it effectively reduced uncertainty risk to 8.3% with low conservativeness, demonstrating superior performance compared to recent methods.

Small Region, Big Impact: Highly Anisotropic Lyman-continuum Escape from a Compact Starburst Region with Extreme Physical Properties

Extreme, young stellar populations are considered to be the primary contributor to cosmic reionization. How the Lyman continuum (LyC) escapes these galaxies remains highly elusive, and it is challenging to observe this process in actual LyC emitters without resolving the relevant physical scales. We investigate the Sunburst Arc, a strongly lensed LyC emitter at z = 2.37 that reveals an exceptionally small-scale (tens of parsecs) region of high LyC escape. The small (<100 pc) LyC-leaking region has extreme properties: a very blue UV slope (β = −2.9 ± 0.1), a high ionization state ([O iii] λ5007/[O ii] λ3727 = 11 ± 3 and [O iii] λ5007/Hβ = 6.8 ± 0.4), strong oxygen emission (EW([O iii]) = 1095 ± 40 Å), and a high Lyα escape fraction (0.3 ± 0.03), none of which are found in nonleaking regions of the galaxy. The leaking region’s UV slope is consistent with approximately “pure” stellar light that is minimally contaminated by the surrounding nebular continuum emission or extinguished by dust. These results suggest a highly anisotropic LyC escape process such that LyC is produced and escapes from a small, extreme starburst region where the stellar feedback from an ionizing star cluster creates one or more “pencil-beam” channels in the surrounding gas through which LyC can directly escape. Such anisotropic escape processes imply that random sight-line effects drive the significant scatters between measurements of galaxy properties and LyC escape fraction, and that strong lensing is a critical tool for resolving the processes that regulate the ionizing budget of galaxies for reionization.

Artificial Post-Cycled Structure Modulation Towards Highly Stable Li-Rich Layered Cathode.

High-capacity Li-rich layered oxides (LLOs) suffer from severe structure degradation due to the utilization of hybrid anion- and cation-redox activity. The native post-cycled structure, composed of progressively densified defective spinel layer (DSL) and intrinsic cations mixing, is deemed as the hindrance of the rapid and reversible de/intercalation of Li+ . Herein, the artificial post-cycled structure consisting of artificial DSL and inner cations mixing is in situ constructed, which would act as a shield against the irreversible oxygen emission and undesirable transition metal migration by suppressing anion redox activity and modulating cation mixing. Eventually, the modified DSL-2% Li-rich cathode demonstrates remarkable electrochemical properties with a high discharge capacity of 187 mAh g-1 after 500 cycles at 2 C, and improved voltage stability. Even under harsh operating conditions of 50 °C, DSL-2% can provide a high discharge capacity of 168 mAh g-1 after 250 cycles at 2 C, which is much higher than that of pristine LLO (92 mAh g-1 ). Furthermore, the artificial post-cycled structure provides a novel perspective on the role of native post-cycled structure in sustaining the lattice structure of the lithium-depleted region and also provides an insightful universal design principle for highly stable intercalated materials with anionic redox activity.

MASTER OT J030227.28+191754.5: A Dwarf Nova at a Massive Oxygen–Neon White Dwarf System?

We present timing and spectral analysis results of the NICER and NuSTAR observations of the dwarf nova MASTER OT J030227.28+191754.5 during the 2021–2022 outburst. The soft X-ray component was found to be dominated by blackbody radiation with a temperature of ∼30 eV and also showed prominent oxygen and neon emission lines. The blackbody luminosity exceeded 1034 erg s−1, which is consistent with theoretical predictions, and then decreased more than an order of magnitude in 3.5 days. The inferred abundances of oxygen and neon in the optically thin coronal region surrounding the central white dwarf (WD) are several times higher than the respective solar values. Although inconclusive, the abundance enrichment may originate from the WD, indicating that it may be mainly composed of oxygen and neon. Assuming that the blackbody radiation comes from the belt-shaped boundary layer between the WD and the accretion disk, we estimated the WD radius to be (2.9 ± 1.1) × 108 cm, which corresponds to the WD mass range of 1.15–1.34 M ⊙. If the accretion continues for another ∼1 Gyr, the WD may experience an accretion-induced collapse into a neutron star and form a so-called black widow pulsar system.

Examining the Properties of Low-luminosity Hosts of Type Ia Supernovae from ASAS-SN

We present a spectroscopic analysis of 44 low-luminosity host galaxies of Type Ia supernovae (SNe Ia) detected by the All-Sky Automated Survey for Supernovae (ASAS-SN), using hydrogen, oxygen, and sulfur emission lines to measure metallicities and star formation rates. We find no statistically significant evidence that the star formation activity and metallicities of the galaxies in our sample are inconsistent with galaxies of similar luminosities and masses. We identify two 3σ outlier galaxies that have high metallicities for their stellar masses, but find that their other properties are consistent with general galaxies. The overall consistency between our sample and general galaxy samples further strengthens the evidence from more luminous SN Ia host galaxy samples that SN Ia host galaxies are typical.

CO2 as the main parent source of atomic oxygen in comet C/2017 K2 (Pan-STARRS)

C/2017 K2 (Pan-STARRS) is an Oort cloud comet discovered in May 2017. Ground observations have revealed that this long-period comet was active at heliocentric distance of 35 au. At such a distance, activity cannot be driven by the sublimation or the exothermic crystallization of water ice. We assume that the activity of comet C/2017 K2 may be driven by the sublimation of super-volatile ices such as CO and CO2. The nature of parent molecules driving the unprecedented activity of comet C/2017 K2 can be investigated by analyzing its spectrum. In particular, the analysis of atomic oxygen emission lines and the calculation of the green (5577.339 Å) to red (6300.304 and 6363.776 Å) line intensity ratio (hereafter G/R) can reveal the nature of molecules driving cometary activity. We report on the detection of atomic oxygen lines in the spectra of comet C/2017 K2 (Pan-STARRS) from high-resolution spectra obtained at the Telescopio Nazionale Galileo (TNG) on 24 June and 2 July 2022 using the High Accuracy Radial velocity Planet Searcher North (HARPS-N) echelle spectrograph. We found G/R ratios equal to 0.29±0.02 (24 July 2022) and 0.27±0.01 (2 July 2022), which are consistent with a cometary activity driven by CO2, even if located at 2.8 au from the Sun. To better define the nature of the driving molecule, we measured the width of the three oxygen lines and found that the green line in the spectrum of 24 July 2022 is wider than either of the two red lines. This allows us to argue that CO2 is dissociated by highly energetic solar photons that produce O(1S) with a large excess velocity.

Nitrogen enhancements 440 Myr after the big bang: supersolar N/O, a tidal disruption event, or a dense stellar cluster in GN-z11?

ABSTRACT Recent observations of GN-z11 with JWST/NIRSpec revealed numerous oxygen, carbon, nitrogen, and helium emission lines at z = 10.6. Using the measured line fluxes, we derive abundance ratios of individual elements within the interstellar medium (ISM) of this superluminous galaxy. Driven by the unusually-bright N iii] λ1750 and N iv] λ1486 emission lines (and by comparison, faint O iii] λλ1660, 1666 lines), our fiducial model prefers log (N/O) &amp;gt; −0.25, greater than four times solar and in stark contrast to lower-redshift star-forming galaxies. The derived log (C/O) &amp;gt; −0.78, (≈30 per cent solar) is also elevated with respect to galaxies of similar metallicity (12 + log (O/H) ≈ 7.82), although less at odds with lower-redshift measurements. We explore the feasibility of achieving these abundance ratios via several enrichment mechanisms using metal yields available in the literature. Given the long time-scale typically expected to enrich nitrogen with stellar winds, traditional scenarios require a very fine-tuned formation history to reproduce such an elevated N/O. We find no compelling evidence that nitrogen enhancement in GN-z11 can be explained by enrichment from metal-free Population III stars. Interestingly, yields from runaway stellar collisions in a dense stellar cluster or a tidal disruption event provide promising solutions to give rise to these unusual emission lines at z = 10.6, and explain the resemblance between GN-z11 and a nitrogen-loud quasar. These recent observations showcase the new frontier opened by JWST to constrain galactic enrichment and stellar evolution within 440 Myr of the big bang.

ASU model with multiple adjustment types for oxygen scheduling concerning pipe pressure safety in steel enterprises

Steel production requires enough oxygen, which is produced by cryogenic air separation (ASU) with a large load, high power, and slow adjustment. Facing complex oxygen demands, effective ASU scheduling can reduce energy waste and has great potential for low-carbon development. Current ASU scheduling models have only a sole load-adjustment type. To address the limitation, a novel scheduling framework model is researched for ASUs with various load-adjustment types, and is applied to an oxygen system scheduling mode1 for steel enterprises. In addition, current multi-period oxygen scheduling models have an issue that time discretization leads to oxygen pipe pressure deviation between model calculation and practical operation and impacts on system safety. Therefore, a novel method to compensate for pressure boundaries is studied to precisely handle the deviation. Some contrast tests concerning various load-adjustment types of ASU are conducted with simulative and real data. The simulative tests indicate that the framework can both unify multiple adjustment types (MAT) and flexibly migrate among various ASUs. In the real scenario, the oxygen scheduling model with the MAT-ASU avoids oxygen emission and reduces comprehensive cost (including electricity consumption and oxygen release loss) of the manual scheduling by 24%. The MAT enhances the response ability to complicated demands, thereby performing better to optimize the comprehensive cost. Though smaller pipe volume or larger discrete period size increases the pressure deviation, the compensation method perfectly ensures safe system operation.

Multispectral singlet oxygen luminescent dosimetry (MSOLD) for Photofrin-mediated Photodynamic Therapy.

Direct detection of singlet-state oxygen ([1O2]) constitutes the holy grail dosimetric method for type II PDT, a goal that can be quantified using multispectral singlet oxygen dosimetry (MSOLD). However, the short lifetime and extremely weak nature of the singlet oxygen signal produced has given rise to a need to improve MSOLD signal-to-noise ratio. This study examines methods for optimizing MSOLD signal acquisition, specifically employing an orthogonal arrangement between detection and PDT treatment light, consisting of two fiber optics - connected to a 632-nm laser and an InGaAs detector respectively. Light collected by the InGaAs detector is then passed through a filter wheel, where spectral emission measurements are taken at 1200 nm, 1240 nm, 1250 nm, 1270 nm, and 1300 nm. The data, after fitting to the fluorescence background and a gaussian-fit for the singlet oxygen peak, is established for the background-subtracted singlet oxygen emission signal. The MSOLD signal is then compared with the singlet oxygen explicit dosimetry (SOED) results, based on direct measurements of in-vivo light fluence (rate), in-vivo Photofrin concentration, and tissue oxygenation concentration. This study focuses on validating the sensitivity and minimum detectability of MSOLD signal in various in-vitro conditions. Finally, the MSOLD device will be tested in Photofrin-mediated PDT for mice bearing Radiation-Induced Fibrosarcoma (RIF) tumors.

Empirical study of the effect of the air filter on the performance and exhaust emissions of a diesel engine

The results of an experimental study of the effect of the pressure drop of the air filter pf on the operat-ing parameters and exhaust emissions of a modern CI internal combustion engine of a truck equipped with an electronically controlled power system are presented. The tests were carried out for an air filter with a clean filter cartridge Δpf0 = 0,58 kPa and with a cartridge contaminated after a service mileage (about 50 thousand km) ΔpfD = 2,024 kPa. In each test, engine performance, exhaust emissions and relative change in emissions were determined: CO, NOx, HC, CO2, H2O. It was found that an increase in the filter resistance pf causes a decrease in the filling degree by 12%, engine useful power by almost 10%, exhaust gas temperature by a maximum of 30oC and an increase in specific fuel consumption by almost 5%. Air filter resistance has no significant effect on NOx emissions and HC concentration. There is a reduction in H2O emissions by up to 7%, CO by up to 13% and CO2 by up to 4%, and an increase in oxygen emissions by 15%, depending on operating conditions.