bluuebunny/crossref_metadata_2025 huggingface dataset:
Diel changes of nitrogen species in surface and overlying water of an estuarine lake in summer: Evidence for benthic‐pelagic coupling
Authors: Yamamuro Masumi , Koike Isao
Published: May 2010

Diel changes in the concentration of nitrogen species [ammonium, nitrite, nitrate, dissolved organic N, and particulate organic N (PON)] and some biological parameters were monitored in the water column of Lake Shinji, a shallow estuarine lake in Japan. The sediment of the lake was densely inhabited by the filter‐feeding bivalve Corbicula japonica. An overlying water sampler showed that PON at the sediment‐water interface (less than a few millimeters above the sediment) was not depleted; nevertheless, active uptake of PON by C. japonica (10.4 mg‐atoms N m−2 (1−1) is reported. Dissolved and particulate N species showed vertically uniform profiles at night, which we attributed to nocturnal water mixing associated with cooling surface water. These observations suggest benthic‐pelagic coupling between filter‐feeding bivalves and phytoplankton which enables the removal of nitrogen from the eutrophic lake through fisheries yield of bivalves.
Temporal variability in settlement of a coastal fish (Sillaginodes punctata) determined by low‐frequency hydrodynamics
Authors: Jenkins Gregory P. , Black Kerry P.
Published: May 2010

The temporal pattern of settlement of King George whiting (Sillaginodes punctata) in Port Phillip Bay, Australia, was compared with the temporal ingress of passive particles to the bay from adjacent coastal waters, predicted by a numerical hydrodynamic and dispersal model. The settlement data and the numerical model showed significantly correlated pulsing on an approximate 10–14‐d period. Pulsing was not obviously associated with individual oceanographic or climatic variables but was most likely caused by a combination of factors related to the passage of pressure systems and associated rotating winds that occur on a 7–14‐d cycle in this region. Such factors may include low‐frequency oscillations related to barometric pressure, reversals in longshore currents, and coastal trapped waves. Additionally, these processes would interact with the spring‐neap tidal cycle. The strong tidal currents in the region of settlement may overwhelm the behavioral responses of larvae and cause them to act as passive particles. High interannual variability in recruitment of S. punctata may relate to variation in the frequency and timing of hydrodynamic events that allow transport of larvae to juvenile habitats.
Plaster standards to measure water motion
Authors: Thompson T. Lewis , Glenn Edward P.
Published: May 2010

Plaster of paris blocks (clod cards) were re‐evaluated as devices to measure water motion in freshwater and marine environments. Clod cards, developed in 1971, have only been used as indicators of relative water motion. We generated standard curves relating the dissolution rates of clod cards to water speed, temperature, and salinity by attaching the cards to a mechanical arm rotating in a tank of water. Free convection experiments were also conducted by suspending clod cards in quiescent solutions held in ice chests. We describe calibration methods that use either forced convection or free convection to correct field results for the effects of temperature and salinity on dissolution rates of clod cards. Although dissolution rates were lower in freshwater than brackish or seawater, salinity in the range of 20–40‰ did not greatly affect dissolution. Properly calibrated, clod cards now offer a simple, practical method for measuring integrated water motion, expressed in readily visualized rate units, over a wide range of temperatures, salinities, and water speeds.
Role of Belostoma bakeri (Heteroptera) in the trophic ecology of a fishless desert spring
Authors: Runck Clay , Blinn Dean W.
Published: May 2010

We examined the foraging and production ecology of a top predator (Belostoma bakeri, Belostomatidae) in the fishless, thermally constant aquatic ecosystem of Montezuma Well, Arizona. Our results highlight the importance of prey behavior in energy flow in aquatic ecosystems. B. bakeri captured more amphipods (Hyalella montezuma) than damselfly nymphs (Telebasis salva) in laboratory experiments; H. montezuma spent significantly more time moving than damselfly nymphs did. Also, B. bakeri captured significantly more adult (≥ 3 mm) amphipods than juveniles (<3 mm) in the light but not in dark treatments. Production by B. bakeri was 2.8 g dw m−2 yr−1 (±2 SE = 0.3). Mean annual standing stock was 0.214 g m−2, annual P:B̄ ratio was 13.3, cohort P:B̄ was 4.7, and annual energy production was 5.88 × 104 J m−2 yr−1. Ecological efficiency was 13.2% between primary producers and amphipods in Montezuma Well, 5.1% between amphipods and damselfly nymphs, and 2.7% between lower levels and aquatic heteropterans. Production by B. bakeri made up 25% of the total energy incorporated in secondary consumer production and accounted for 72% of the production by the top predators in Montezuma Well.
CO2 availability, carbonic anhydrase, and the annual dinoflagellate bloom in Lake Kinneret
Authors: Berman-Frank Ilana , Zohary Tamar , Erez Jonathan , Dubinsky Zvy
Published: May 2010

Changes with time in the concentration of inorganic carbon in Lake Kinneret subsurface water were followed throughout two seasonal dinoflagellate blooms. The response of natural populations of the dominant dinoflagellate, Peridinium gatunense, to these changes was recorded by examining fluctuations over time in the activity of the enzyme carbonic anhydrase (CA) and in photosynthetic parameters. Our results show distinct fluctuations of both external and cytoplasmic CA activity in P. gatunense throughout the annual bloom. Higher levels of activity were triggered by the decline of total dissolved inorganic C below 1.8 mM and more specifically by low concentrations of dissolved CO2 (1–10 µM) during the seasonal bloom decline in May–June. Laboratory studies on cultured P. gatunense confirmed our field observations, suggesting that supplemental mechanisms are activated in P. gatunense that enhance inorganic C uptake when CO2 is limiting for photosynthesis.

Eventually, the cellular adaptations of P. gatunense to the declining CO2 concentrations could not prevent decline of photosynthetic rates contributing to the subsequent decrease in P. gatunense biomass in May–June. In Lake Kinneret, P. gatunense is succeeded by Peridiniopsis spp., the photosynthetic rates and external CA activities of which were much higher under environmental conditions typical of the end of the bloom.
Carbon‐isotope fractionation by a marine diatom: The influence of irradiance, daylength, pH, and nitrogen source
Authors: Thompson Peter A. , Calvert Stephen E.
Published: May 2010

We examined the carbon‐isotope composition of Thalassiosira pseudonana grown under different combinations of irradiance and daylength with nitrate or ammonium as the nitrogen source. The relationship between the concentration of dissolved inorganic carbon and δ13C of T. pseudonana strongly suggested that HCO3− was the major source of carbon for growth regardless of pH or nitrogen species. The discrimination against 13C (εp) was significantly influenced by daylength, irradiance, and the interaction of daylength with irradiance. Discrimination was lower when daylengths were 16 : 8 and 20 : 4 L/D. Discrimination was minimal at irradiances of 25–50 µmol photons m−2 s−1. Natural variation in the concentration of CO2(aq) seems unlikely to influence the δ13C of T. pseudonana, whereas daylength and irradiance probably influence the δ13C of natural samples of particulate organic matter. We suggest that geochemical models that use δ13C measurements from sedimented material to hindcast the partial pressure of CO2 may need reevaluation.
Effect of forest and savanna vegetation on the carbon‐isotope composition of sediments from the Sanaga River, Cameroon
Authors: Bird M. I. , Giresse P. , Chivas A. R.
Published: May 2010

The carbon‐isotope composition (δ13C) of organic matter from modern sediments in the Sanaga River basin, Cameroon, shows a progressive downriver decrease in δ13C values. Sediments in tributaries draining montane grassland regions have consistent δ13C values of ∼−19‰, while rivers draining savanna regions have δ13C values of around −22‰. After the river passes through extensively forested regions, the 13C values of the sediments closest to the mouth of the river decrease to −25‰. Samples collected from rivers with entirely forested catchment had low δ13C values (from −27 to −29‰) consistent with a pure C3 vegetation source. The downriver carbon‐isotope trends are consistent with the hypothesis that observed variations are due to changes in the relative proportions of C3 and C4 carbon in the sediments, which are derived from terrestrial vegetation in the river catchment.

Some sediments from the Mbam River, the principal tributary of the Sanaga River, have extremely high δ13C values (up to −16.7‰). These high values may be the result of severe erosion in the densely populated and intensively farmed Bamileke region in the headwaters of the Mbam.

An underrepresentation of C4‐derived carbon in the upper reaches of the Sanaga is possibly due to the damming of the Djerem River at Mbakaou. Since the dam was constructed <25 yr ago, this suggests that the δ13C value of river sediments responds rapidly to changes in the basin.
Increased phototaxis in the field leads to enhanced diel vertical migration
Authors: Ringelberg J. , Flik B. J. G.
Published: May 2010

Downward and upward displacement velocity of diel vertical migration in Lake Maarsseveen by the hybrid Daphnia galeata × hyalina, was correlated with the relative change in light intensity at dawn and dusk, indicating a phototactic basis for these migrations. The significance of the regression function increased over a period of 4 yr. Changes in environmental factors such as water transparency and food concentration are not responsible.
Oligosaccharide degradation by anaerobic marine bacteria: Characterization of an experimental system to study polymer degradation in sediments
Authors: Arnosti C. , Repeta D. J.
Published: May 2010

Enrichment of bacteria from anoxic marine sediments on specific carbohydrates yielded a reproducible model system with which to compare the degradation of a set of structurally related substrates. The goal was to approximate thc diversity of natural mixed microbial populations while reducing the complexity of studying the degradation of specific substrates in sediments. Structurally related substrates were used to compare the influence of substrate size, chemical linkage, and stereochemistry on carbohydrate degradation. Headspace gases (CO2, H2, CH4, H2S) were monitored by gas chromatography, and carbohydrate substrates were separated and quantified with high‐pressure liquid chromatography. The sequence of transformations observed in the cultures is consistent with the sequential substrate degradation expected in a consortium of anaerobic bacteria, and the transfer of carbon from substrates through to end products was followed quantitatively. A series of experiments showed that mixed cultures of marine bacteria distinguish between even small, closely related substrates that do not require extracellular hydrolysis prior to uptake. A galactose‐β(1,3)‐arabinose disaccharide (GLA) was degraded at half the rate of seven other similar disaccharides and three larger oligosaccharides. Results from transfer cultures indicate that the ability to degrade GLA probably is not widespread among bacteria. Although neither the component monomers of GLA nor its β(1,3) linkage is uncommon in marine environments, its specific combination of a hexose and a pentose may not fit standard carbohydrate transport systems in bacteria. Substrate structural features clearly can have a significant effect on degradation rates, even at molecular weights below the direct transport size limit.
Long‐term 15N‐nitrogen retention in the vegetated sediments of a New England salt marsh
Authors: White David S. , Howes Brian L.
Published: May 2010

15N was used in a 7‐yr field study and a laboratory investigation of a single growing season to quantify the amount, timing, and mechanisms of annual N retention and loss in the plant‐sediment system of a short Spartina alterniflora marsh. There was an initial rapid loss of ∼25% of the added 15NH4+ through nitrification‐denitrification at a rate of 25.2 mg N m−2 d−1, with the remaining label being incorporated into plant tissues. Label losses decreased throughout the study as15N was increasingly sequestered in the dead organic N pool. About 40% of the injected label remained after seven growing seasons. Total annual N losses were 7.3–7.6 g N m−2 yr−1 based on 15N losses and estimates of the actively cycling N pool. Export accounted for 26–44% and denitrification for 54–77% of the total N loss. Burial of N in dead belowground organic matter was 3.7–4.1 g N m−2 yr− 1, similar to estimates determined from accretion and total sediment N data. Recycling of N through translocation from aboveground to belowground biomass and remineralization of dead belowground biomass was the major pathway in the sediment N cycle, equivalent to 67–79% of the annual plant N demand. Annual N losses were balanced by inputs, primarily N2 fixation. Long‐term N retention appears to be controlled primarily by the competition for DIN between the plants and bacterial nitrifiers‐denitrifiers and secondarily by the relative incorporation of N into aboveground vs. belowground biomass.
Use of radium isotopes to examine pore‐water exchange in an estuary
Authors: Webster Ian T. , Hancock Gary J. , Murray Andrew S.
Published: May 2010

The measured distributions of four isotopes of Ra along the estuary of the Bega River are used to examine sediment‐water column exchange. Ra is created in estuarine sediments by the radioactive decay of insoluble Th parents residing close to or on the surfaces of the sediment grains. Ra desorbed into the pore water is continuously lost to the water column due to the cyclical draining and filling of the sediments by the tides. The distribution of Ra in the estuary is governed by its rate of loss from the sediments, its advection along the estuary resulting from river discharge into the estuary’s head, tidal mixing, and radioactive decay. These processes are all described in a model. Matching of model‐predicted Ra concentrations with measurements allows an estimate of the effective depth in the sediments to which the pore water is exchanged every tidal cycle. This depth is large (15 cm), but it is shown to be reasonable for the Bega estuary.
A fast‐response oxygen sensor for use on fine‐scale and microstructure CTD profilers
Authors: Oldham Carolyn
Published: May 2010

A specialized oxygen sensor is described whose fast response times make it ideal for studies of the effects of mixing processes on oxygen concentrations. A polarographic oxygen microelectrode was installed on a microstructure CTD profiler. The oxygen microelectrode has a tip size of 30 µm, a total length of 5 cm, membrane thickness of <4 µm, and a time constant of 0.13 s. Flow dependence is minimal, and the amplifying and conditioning electronics are installed inside the body of the profiler, which is 50 cm long and 10 cm in diameter. The profiler samples temperature, gradient temperature, conductivity, dissolved oxygen, and pressure as it ascends through the water column at 10 cm s−1. Sampling at 100 Hz allows temperature, conductivity, and depth measurements every 1 mm and dissolved oxygen measurements every 1.3 cm.
High‐resolution pore‐water sampling with a gel sampler
Authors: Krom M. D. , Davison P. , Zhang H. , Davison W.
Published: May 2010

Sediment pore‐water profiles were sampled at high resolution (millimeter scale) with a polyacrylamide gel probe. This simple procedure involves inserting a 1‐mm‐thick gel held in a plastic probe into sediment. The gel reaches diffusive equilibrium in <1–2 h. For anions, the gel was sectioned, back‐equilibrated into distilled‐deionized water, and anions determined by high‐performance liquid chromatography. Laboratory trials showed recovery of 104±4% Cl, 102±2% NO3, 101±1% SO4, and 102±2% NH4. For Fe and Mn, the gel was fixed in 0.01 M NaOH for ∼3 h, subsectioned, extracted with 1 M HNO3, and analyzed by atomic absorption spectrometry. Field trials were undertaken in Esthwaite Water, a seasonally anoxic lake in the English Lake District. Gel probe data compared well with conventional pore‐water extractions.
Determination of alkaline phosphatase‐hydrolyzable phosphorus in natural water systems by enzymatic flow injection
Authors: Shun Ying , McKelvie Ian D. , Hart Barry T.
Published: May 2010

We report an enzymatic flow injection method for automatic measurement of dissolved phosphatase‐hydrolyzable phosphorus. The method involves use of immobilized Escherichia coli alkaline phosphatase, which produces orthophosphate from phosphate monoesters, nucleoside polyphosphate, deoxynucleoside polyphosphate, inorganic pyrophosphate, tripolyphosphate, and some S‐phosphorothioate esters. The liberated orthophosphate is subsequently detected as phosphomolybdenum blue. Suppression of E. coli alkaline phosphatase activity is significantly reduced when the enzyme is immobilized and used in a packed‐bed reactor. This method offers a means of characterizing organic P compounds in the dissolved nutrient pool and has been successfully applied to the study of freshwaters, wastewaters, and sediment extracts. Phosphatase‐hydrolyzable P has potential use as an indicator of bioavailability of dissolved P other than orthophosphate in natural waters.
Perceptions of Agricultural Education Instructors of the Relationship of Shooting Sports in Agricultural Education
Authors: Scales Jason , Terry Robert , Jr.
Published: May 2010

As agricultural education has diversified to include courses and units on natural resource management, skill development activities and competitions related to this area have become more common for students and FFA members. This study was designed to assess the relationship between shooting sports and the agricultural education program. More specifically, this study sought to describe agricultural education instructors who sponsor a shooting sports program through the FFA and determine their perceptions related to their students’ participation in shooting sports activities. Agricultural education instructors agreed that shooting sports is a valuable activity to the agricultural education program. Forty percent of the respondents indicated that curriculum related to fish and wildlife management was most related to shooting sports and firearm safety. Recommendations resulting from this study include future research about understanding the relationship between agriculture education and shooting sports.
Beyond Mere Enrollment: Level of Youth Organization Participation as a Predictor of Collegiate Academic Success and Retention
Authors: Smith Amy R. , Garton Bryan L. , Kitchel Tracy J.
Published: May 2010

Limited support exists documenting the value of secondary agriculture programs and participation in the National FFA Organization. To that end, the purpose of this study was to explore the suggested value in relationship to student performance and retention in college. The longitudinal trend–type study sought to determine if students who had been enrolled in a secondary agriculture program had greater academic performance during the first year of college. In addition, the study investigated whether a relationship existed between the level of student involvement in a secondary agriculture program and academic performance. Finally, the existence of a relationship between secondary agriculture enrollment and retention in college was examined. The target population for this ex–post facto study consisted of two time and place samples of entering college freshmen (1998 and 2003) at the University of Missouri. Findings revealed that enrollment in secondary agriculture did not consistently produce greater academic performance in college. Additionally, there was no conclusive relationship found between level of involvement in secondary agriculture and academic performance or retention in college.
Perceptions of Preservice Teachers Toward Integrating Science Into School-Based Agricultural Education Curriculum
Authors: Thoron Andrew C. , Myers Brian E.
Published: May 2010

Agricultural education is at an interesting point in the cycle of agriscience integration. Current preservice teachers have had the opportunity to be taught in both secondary and post-secondary programs that have fully embraced agriscience integration. This study investigates the perceptions of these budding agricultural educators toward science integration. The perceptions of 191 preservice teachers who responded to the questionnaire concurred with most perceptions of inservice teachers as reported in other studies. Preservice teachers indicate an intention to increase the amount and quality of integration in their future classrooms compared to what they perceive occurring today and that this will result in an increase in student enrollment. They also suggested increasing the number of science courses in the preservice curriculum and placing student teachers with inservice teachers who have successfully integrated science in agriculture.
Learning Disabled Student Needs Met Through Curriculum Redesign of the Illinois Agricultural Education Core Curriculum
Authors: Pense Seburn L. , Watson Dennis G. , Wakefield Dexter B.
Published: May 2010

This quasi–experimental pilot study included agricultural education students with Specific Learning Disabilities (SLD) in five high schools in the federally designated economically distressed area called the Illinois Delta Region. A unit of instruction taken from the existing 165 units of The Illinois Core Curriculum for Agriculture was redesigned in a manner appropriate to SLD students. Students from the five selected programs were randomly assigned to treatment and control groups. Results from pre– and posttests in this study found the redesigned curriculum for SLD students effectively increased learning for both SLD and traditional students.
Direct radiative effect of aerosols emitted by transport: from road, shipping and aviation
Authors: Balkanski Y. , Myhre G. , Gauss M. , Rädel G. , Highwood E. J. , Shine K. P.
Published: May 2010

Abstract. Aerosols and their precursors are emitted abundantly by transport activities. Transportation constitutes one of the fastest growing activities and its growth is predicted to increase significantly in the future. Previous studies have estimated the aerosol direct radiative forcing from one transport sub-sector, but only one study to our knowledge estimated the range of radiative forcing from the main aerosol components (sulphate, black carbon (BC) and organic carbon) for the whole transportation sector. In this study, we compare results from two different chemical transport models and three radiation codes under different hypothesis of mixing: internal and external mixing using emission inventories for the year 2000. The main results from this study consist of a positive direct radiative forcing for aerosols emitted by road traffic of +20±11 mW m−2 for an externally mixed aerosol, and of +32±13 mW m−2 when BC is internally mixed. These direct radiative forcings are much higher than the previously published estimate of +3±11 mW m−2. For transport activities from shipping, the net direct aerosol radiative forcing is negative. This forcing is dominated by the contribution of the sulphate. For both an external and an internal mixture, the radiative forcing from shipping is estimated at −26±4 mW m−2. These estimates are in very good agreement with the range of a previously published one (from −46 to −13 mW m−2) but with a much narrower range. By contrast, the direct aerosol forcing from aviation is estimated to be small, and in the range −0.9 to +0.3 mW m−2.
In-situ observations of young contrails – overview and selected results from the CONCERT campaign
Authors: Voigt C. , Schumann U. , Jurkat T. , Schäuble D. , Schlager H. , Petzold A. , Gayet J.-F. , Krämer M. , Schneider J. , Borrmann S. , Schmale J. , Jessberger P. , Hamburger T. , Lichtenstern M. , Scheibe M. , Gourbeyre C. , Meyer J. , Kübbeler M. , Frey W. , Eichler H. , Butler T. , Lawrence M. G. , Holzäpfel F. , Arnold F. , Wendisch M. , Döpelheuer A. , Gottschaldt K. , Baumann R. , Zöger M. , Sölch I. , Rautenhaus M. , Dörnbrack A.
Published: May 2010

Abstract. Lineshaped contrails were detected with the research aircraft Falcon during the CONCERT – CONtrail and Cirrus ExpeRimenT – campaign in October/November 2008. Thereby the Falcon was equipped with a set of instruments to measure particle properties such as the particle size distribution, shape, extinction, chemical composition as well as trace gas concentrations of sulfur dioxide (SO2), reactive nitrogen and halogen species (NO, NOy, HNO3, HONO, HCl), ozone (O3) and carbon monoxide (CO). During 12 mission flights over Western Europe numerous contrails and cirrus clouds were probed at altitudes between 8.5 and 11.6 km and temperatures above 213 K. 22 contrails from 11 different aircraft were observed near and below ice saturation. The observed NO mixing ratios, ice crystal and soot number densities are compared to a process based contrail model. Further we investigate in detail the contrail from a CRJ-2 aircraft detected on 19 November 2008 in 10.1 km altitude. The contrail with an age of 1 to 2 min had average ice crystal concentrations of 128 cm−3 in the size range 0.4
The contribution of historical aerial and satellite photos to archaeological and geo-archaeological research: case studies in Italy and Turkey
Authors: Scardozzi G.
Published: May 2010

Abstract. The paper evidences the importance of old aerial and satellite photos of ancient topography studies, with examples concerning archaeological and geo-archaeological research conducted in Italy and Turkey, during a cooperation between the Ancient Topography, Archaeology and Remote Sensing Laboratory (AnTAReS Lab) of the Institute for Archaeological and Monumental Heritage of the Italian National Research Council (IBAM-CNR) and the Ancient Topography and Photogrammetry Laboratory (LabTAF) of Salento University. The historical aerial photos, i.e. those before the big transformations of the 1950's and 1960's, and the space photos taken in the 1960's and 1970's, particularly useful for the Near East, represent a fundamental tool for the study of the territory. In many cases, in fact, they document landscapes that have been modified by urbanization, building of large infrastructures, transformations in the land use and diffusion of mechanized agricultural methods. Only through the detailed analysis of these aerial and space photos it is possible to recover a fundamental documentation concerning the existence, the location and the layout of archaeological evidence and paleo-environmental elements otherwise lost; so, their use during research is very important for the reconstruction of the ancient topography of urban and territorial contexts.
Abnormal dynamic functional connectivity in young nondisabling intracerebral hemorrhage patients
Authors: Yang Dan , Luo Xiangqi , Sun Shengjun , Zhang Xue , Zhang Fengxia , Zhao Xingquan , Zhou Jian
Published: May 2024

Objective

Previous resting‐state functional magnetic resonance imaging studies on intracerebral hemorrhage patients have focused more on the static characteristics of brain activity, while the time‐varying effects during scanning have received less attention. Therefore, the current study aimed to explore the dynamic functional network connectivity changes of intracerebral hemorrhage patients.

Methods

Using independent component analysis, the sliding window approach, and the k‐means clustering analysis method, different dynamic functional network connectivity states were detected from resting‐state functional magnetic resonance imaging data of 37 intracerebral hemorrhage patients and 44 healthy controls. The inter‐group differences in dynamic functional network connectivity patterns and temporal properties were investigated, followed by correlation analyses between clinical scales and abnormal functional indexes.

Results

Ten resting‐state networks were identified, and the dynamic functional network connectivity matrices were clustered into four different states. The transition numbers were decreased in the intracerebral hemorrhage patients compared with healthy controls, which was associated with trail making test scores in patients. The cerebellar network and executive control network connectivity in State 1 was reduced in patients, and this abnormal dynamic functional connectivity was positively correlated with the animal fluency test scores of patients.

Interpretation

The current study demonstrated the characteristics of dynamic functional network connectivity in intracerebral hemorrhage patients and revealed that abnormal temporal properties and functional connectivity may be related to the performance of different cognitive domains after ictus. These results may provide new insights into exploring the neurocognitive mechanisms of intracerebral hemorrhage.
Method and Application of Surface Modification of Cerium Dioxide
Authors: Wang Wei , Xu Wenying , Zhao Zhiwei , Cheng Mingyan , Xun Menghan , Liu Huimin
Published: May 2024

Airborne pollutants, such as nitrogen oxides (NOx), and waterborne contaminants, including heavy metals, dyes, and other pollutants, pose substantial environmental threats and jeopardize human health. Additionally, certain limitations have hindered the widespread application of some batteries, primarily attributed to elevated operating temperatures and the decreasing use of fossil fuels. In response to these challenges, cerium dioxide (CeO2) nanoparticles have garnered considerable attention due to their unique and advantageous physical and chemical properties. Furthermore, the incorporation of CeO2 into various coating materials has demonstrated the potential to significantly enhance their performance. In the realm of biotechnology, research into CeO2 nanoparticles continues to expand, encompassing a range of applications such as the scavenging of reactive oxygen species in biological systems, the development of anti‐inflammatory agents, and cancer research. Nevertheless, in these diverse applications, CeO2 still exhibits certain limitations that hinder the achievement of desired outcomes. The modification of CeO2 nanoparticles presents a promising avenue to address these limitations, thereby improving their overall efficacy. As such, this review aims to comprehensively compare and summarize various methods for the modification of CeO2 nanoparticles, elucidate their practical applications, and provide insights into the potential challenges and future prospects in this field.
Topological Exciton Polaritons in Compact Perovskite Junction Metasurfaces
Authors: An Soo‐Chan , Lim Yeonsoo , Lee Ki Young , Choi Daegwang , Kim Seongheon , Gong Su‐Hyun , Yoon Jae Woong , Jun Young Chul
Published: May 2024

Exciton polaritons are hybrid light‐matter quasi‐particles that hold exceptional opportunities for future optoelectronic devices. Taking the synergic advantages of room‐temperature perovskite excitons and topological photonic structures, topological exciton‐polaritons are experimentally demonstrated in organic–inorganic hybrid perovskite thin films. Topological junction structures based on perovskite gratings are realized using a momentum‐space analog of the 1D Dirac system. Desired enhancement phenomena are observed including narrow‐beam polariton emission from a tightly localized junction region, polaritonic nonlinearity boost, and enhanced luminescence. These remarkable features are obtained from highly compact devices with footprint widths on the order of a few micrometers and are efficiently tailorable with simple unit‐cell geometry control. Therefore, the proposed approach can be a powerful platform for room‐temperature topological exciton‐polaritons and concomitant device applications.
Manipulating Spin‐Lattice Coupling in Layered Magnetic Topological Insulator Heterostructure via Interface Engineering
Authors: Maity Sujan , Dey Dibyendu , Ghosh Anudeepa , Masanta Suvadip , De Binoy Krishna , Kunwar Hemant Singh , Das Bikash , Kundu Tanima , Palit Mainak , Bera Satyabrata , Dolui Kapildeb , Watanabe Kenji , Taniguchi Takashi , Yu Liping , Taraphder A , Datta Subhadeep
Published: May 2024

Induced magnetic order in a topological insulator (TI) can be realized either by depositing magnetic adatoms on the surface of a TI or engineering the interface with epitaxial thin film or stacked assembly of 2D van der Waals (vdW) materials. Herein, the observation of spin‐phonon coupling in the otherwise non‐magnetic TI Bi2Te3 is reported, due to the proximity of FePS3 (an antiferromagnet (AFM), TN ≈ 120 K), in a vdW heterostructure framework. Temperature‐dependent Raman spectroscopic studies reveal deviation from the usual phonon anharmonicity originated from spin‐lattice coupling at the Bi2Te3/FePS3 interface at/below 60 K in the peak position (self‐energy) and linewidth (lifetime) of the characteristic phonon modes of Bi2Te3 (106 and 138 cm−1) in the stacked heterostructure. The Ginzburg‐Landau (GL) formalism, where the respective phonon frequencies of Bi2Te3 couple to phonons of similar frequencies of FePS3 in the AFM phase, is adopted to understand the origin of the hybrid magneto‐elastic modes. At the same time, the reduction of characteristic TN of FePS3 from 120 K in isolated flakes to 65 K in the heterostructure, possibly due to the interfacial strain, which leads to smaller Fe‐S‐Fe bond angles as corroborated by computational studies using density functional theory (DFT). Besides, inserting hexagonal boron nitride within Bi2Te3/FePS3 stacking regains the anharmonicity in Bi2Te3. Controlling interfacial spin‐phonon coupling in stacked heterostructure can have potential application in surface code spin logic devices.
Tailored Phototherapy Agent by Infection Site In Situ Activated Against Methicillin‐Resistant S. aureus
Authors: Guo Lixia , Tian Yafei , Zhou Liang , Kang Shiyue , Zhang Chengwu , Liu Wen , Diao Haipeng , Feng Liheng
Published: May 2024

Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), is a promising treatment approach for multidrug resistant infections. PDT/PTT combination therapy can more efficiently eliminate pathogens without drug resistance. The key to improve the efficacy of photochemotherapy is the utilization efficiency of non‐radiation energy of phototherapy agents. Herein, a facile phototherapy molecule (SCy‐Le) with the enhancement of non‐radiative energy transfer is designed by an acid stimulation under a single laser. Introduction of the protonated receptor into SCy‐Le results in a distorted intramolecular charge in the infected acidic microenvironment, pH ≈ 5.5, which in turn, enhances light capture, reduces the singlet–triplet transition energies (ΔES1–T1), promotes electron system crossing, enhances capacity of reactive oxygen species generation, and causes a significant increase in temperature by improving vibrational relaxation. SCy‐Le shows more than 99% bacterial killing rate against both methicillin‐resistant Staphylococcus aureus and its biofilms in vitro and causes bacteria‐induced wound healing in mice. This work will provide a new perspective for the design of phototherapy agents, and the emerging photochemotherapy will be a promising approach to combat the problem of antibiotic resistance.
Enhanced Mechanical Strength and Sustained Drug Release in Carrier‐Free Silver‐Coordinated Anthraquinone Natural Antibacterial Anti‐Inflammatory Hydrogel for Infectious Wound Healing
Authors: Liang Xiaoliu , Ding Linyu , Ma Jiaxin , Li Jiwei , Cao Lei , Liu Hui , Teng Minglei , Li Zhenjie , Peng Yisheng , Chen Hu , Zheng Yali , Cheng Hongwei , Liu Gang
Published: May 2024

The persistent challenge of healing infectious wounds and the rise of bacterial resistance represent significant hurdles in contemporary medicine. In this study, based on the natural small molecule drug Rhein self‐assembly to form hydrogels and coordinate assembly with silver ions (Ag+), a sustained‐release carrier‐free hydrogel with compact structure is constructed to promote the repair of bacterial‐infected wounds. As a broad‐spectrum antimicrobial agent, Ag+ can avoid the problem of bacterial resistance caused by the abuse of traditional antibiotics. In addition, due to the slow‐release properties of Rhein hydrogel, continuous effective concentration of Ag+ at the wound site can be ensured. The assembly of Ag+ and Rhein makes the hydrogel system with enhanced mechanical stability. More importantly, it is found that Rhein effectively promotes skin tissue regeneration and wound healing by reprogramming M1 macrophages into M2 macrophages. Further mechanism studies show that Rhein realizes its powerful anti‐inflammatory activity through NRF2/HO‐1 activation and NF‐κB inhibition. Thus, the hydrogel system combines the excellent antibacterial properties of Ag+ with the excellent anti‐inflammatory and tissue regeneration ability of Rhein, providing a new strategy for wound management with dual roles.
Synchronous Switching Strategy to Enhance the Real‐Time Powering and Charging Performance of Triboelectric Nanogenerator
Authors: Xia Yuxuan , Zhi Jinyan , Zhang Ruichao , Zhou Feng , Liu Shuhai , Xu Qi , Qin Yong
Published: May 2024

Triboelectric nanogenerators (TENGs) are of great significance as sustainable power sources that harvest energy from the human body and environment. Nevertheless, due to TENG's impedance‐dependent output voltage characteristics, in traditional strategy (TS), real‐timely powering a sensor with TENG has a poor sensing on/off ratio (or response), and directly charging a capacitor with TENG shows a low charging efficiency. This degraded real‐time powering and charging performance of TENG compared to a commercial constant voltage source is a huge challenge of the TENG field for a long time. This work proposes a synchronous switching strategy (SSS) for TENG to real‐timely power sensors or charge capacitors without degrading its performance. Compared with TS, this new strategy enables sensors to have 5–7 times sensing on/off ratio enhancement when using TENG as a power source, reaching the powering ability of a commercial constant voltage source, it makes the powering performance of TENG stable under different driving frequency, improving the powering robustness of TENG. In addition, compared with TS, SSS can also enhance the charging efficiency of TENG in every charging cycle by up to 2.4 times when charging capacitors. This work contributes to real‐timely powering or charging the distributed, mobile and wireless electronics using TENG.
Deep‐Blue and Fast Delayed Fluorescence from Carbene–Metal–Amides for Highly Efficient and Stable Organic Light‐Emitting Diodes
Authors: Brannan Alexander C. , Cho Hwan‐Hee , Reponen Antti‐Pekka M. , Gorgon Sebastian , Phuoc Nguyen Le , Linnolahti Mikko , Greenham Neil C. , Romanov Alexander S.
Published: May 2024

Linear gold complexes of the “carbene–metal–amide” (CMA) type are prepared with a rigid benzoguanidine amide donor and various carbene ligands. These complexes emit in the deep‐blue range at 424 and 466 nm with 100% quantum yields in all media. The deep‐blue thermally activates delayed fluorescence originates from a charge transfer state with an excited state lifetime as low as 213 ns, resulting in fast radiative rates of 4.7 × 106 s−1. The high thermal and photo‐stability of these carbene–metal–amide (CMA) materials enabled the authors to fabricate highly energy‐efficient organic light‐emitting diodes (OLED) in host–guest architectures. Deep‐blue OLED devices with electroluminescence at 416 and 457 nm with practical external quantum efficiencies of up to 23% at 100 cd m−2 with excellent color coordinates CIE (x; y) = 0.16; 0.07 and 0.17; 0.18 are reported. The operating stability of these OLEDs is the longest reported to date (LT50 = 1 h) for deep‐blue CMA emitters, indicating a high promise for further development of blue OLED devices. These findings inform the molecular design strategy and correlation between delayed luminescence with high radiative rates and CMA OLED device operating stability.
Ultrafast UV Luminescence of ZnO Films: Sub‐30 ps Decay Time with Suppressed Visible Component
Authors: Cadatal‐Raduban Marilou , Olejníček Jiří , Hibino Kota , Maruyama Yuki , Písaříková Aneta , Shinohara Keito , Asaka Toru , Lebedová Volfová Lenka , Kohout Michal , Jiaqi Zhang , Akabe Yugo , Nakajima Makoto , Harrison John A. , Hippler Rainer , Sarukura Nobuhiko , Ono Shingo , Hubička Zdeněk , Yamanoi Kohei
Published: May 2024

Ultrafast sub‐100 picosecond luminescence is vital in many applications involving ultrafast events and time‐of‐flight systems. Materials exhibiting fast luminescence, such as barium fluoride (BaF2) and zinc oxide (ZnO), also suffer from an intrinsically slow nanosecond (ns) to microsecond (µs) luminescence. Here, 2.2 micrometer (µm)‐ to 5.7 µm‐thick undoped ZnO films on soda‐lime glass (SLG) substrates without a buffer layer by a hybrid pulsed reactive magnetron sputtering operating in the medium‐frequency range (MF magnetron) assisted by an electron cyclotron wave resonance (ECWR) plasma is deposited. The undoped ZnO films exhibited superior optical properties characterized by intense ultraviolet (UV) luminescence, unprecedented ultrafast decay times, and for the case of MF+ECWR‐deposited films, suppressed defect‐related visible luminescence. The 2.2 µm‐thick MF‐deposited film exhibited the fastest 9‐ps decay time at room temperature. The impressive properties of the films are attributed to the use of advanced deposition technology with properly tuned plasma parameters, especially a high degree of dissociation of molecular oxygen together with an increased proportion of activated zinc particles, leading to a higher deposition rate, better crystallinity, fewer defects, and a lower proportion of oxygen vacancies. These films will pave the way toward the development of time‐of‐flight detectors, high‐resolution nuclear imaging cameras, and high‐rate ultrafast timing devices.
High‐Performance SiC/Graphene UV‐Visible Band Photodetectors with Grating Structure and Asymmetrical Electrodes for Optoelectronic Logic Gate
Authors: Zhang Zeyang , Sun Cunzhi , Zhu Baihong , Chen Jiadong , Fu Zhao , Li Zihao , Wu Shaoxiong , Zhang Yuning , Cai Jiafa , Hong Rongdun , Lin Dingqu , Fu Deyi , Wu Zhengyun , Chen Xiaping , Zhang Feng
Published: May 2024

High‐quality epitaxial graphene is prepared on semi‐insulated 4H‐SiC (0001) by ultra‐high vacuum thermal decomposition method and used in graphene/SiC/graphene ultraviolet‐visible dual‐band photodetectors. The dual‐band detector exhibits an extremely low dark current (5.2 × 10−14 A) and a peak responsivity of 1.17 A W−1 corresponding to an external quantum efficiency of 518%. A high detectivity of 3.14 × 1014 Jones is achieved under 280 nm light illumination at 30 V, while a high response speed is obtained with a rise time of 25.17 ns and a decay time of 540.10 ns. The detector shows a responsivity of 1.4 × 10−5 A W−1 and a detectivity of 6.5 × 109 Jones under 430 nm light illumination. The dual‐band detector equipped with SiC grating and asymmetrical graphene electrodes is demonstrated for high‐performance optoelectronic logic “AND” gate with high detectivity at 280 and 430 nm.
Electro‐Induced Self‐Reduction TiO2 in Viologen‐Based Ionogels for Multi‐Color Electrochromic Displays
Authors: Fang Rui , Bai Zhiyuan , Wu Xilu , Fan Qingchao , Bao Bingwei , Hou Chengyi , Zhang Qinghong , Li Yaogang , Li Kerui , Wang Hongzhi
Published: May 2024

Reflective electrochromic (EC) technology is expected to e‐paper display field, and integrating optical reflective electrolyte as the optical reflective layer is a common strategy for constructing reflective EC devices. Compositing inorganic particles and electrolytes is one of the simplest and most efficient composite methods, but these composite electrolytes usually cannot perform well together in terms of both optical and electrochemical properties. Herein, the TiO2 nanoparticles are added to the ethyl viologen‐based ionogel (T‐EVG, one typical kind of EC/electrolyte) to have the highest visible light reflectivity and the best electrochemical performance compared with SiO2, Al2O3, and ZnO nanoparticles, which is attributed to the electro‐induced self‐reduction TiO2 produced in T‐EVG during EC cycling. Meanwhile, the corresponding EC devices can display red, green, and blue, and have high optical contrast (CIE Lab: ΔE>38), fast switching spend (<4 s, the fastest is 5 Hz), ultra‐low power density (<4.0 mW cm−2), and excellent cycling stability (>85% retained after 10 000 cycles). Finally, a simple 3×3 pixelated EC display array is prepared, and single‐ and multi‐point (including diagonal points) multi‐color display effects are realized through active‐matrix driving and high‐frequency refresh, demonstrating its application value in the high‐performance e‐paper display.
Improving the Performance of Cooling and Entanglement in a Double Cavity Optomechanical System Assisted by the Quantum Coherent Feedback
Authors: Chen Yuan , Chen Ai‐Xi
Published: May 2024

A theoretical scheme is proposed for improving the performance of cooling and entanglement, where the physical model is based on a double cavity optomechanical system assisted by the field‐mediated coherent feedback. The cooling performance is evaluated by calculating the final mean phonon number. The steady‐state bipartite entanglement between the optical mode and mechanical mode is measured by the logarithmic negativity. The result manifests that with assistance of the quantum coherent feedback, the mechanical resonator (MR) can be cooled close to its quantum ground state and the steady‐state optomechanical entanglement is simultaneously created, all of which are obtained under the condition beyond the resolved sideband. The presented feedback strategy is measurement‐independent, which can effectively preserve the quantum coherence of system. The scheme is conducive to relaxing the current experimental condition and it may provide a new path for the optomechanical manipulation involving the low‐frequency MR.
Electrocatalytic Oxygen Reduction Using Metastable Zirconium Suboxide
Authors: Hu Huashuai , Xu Zhihang , Zhang Zhaorui , Yan Xiaohui , Zhu Ye , Attfield J. Paul , Yang Minghui
Published: May 2024

Strategies for discovery of high‐performance electrocatalysts are important to advance clean energy technologies. Metastable phases such as low temperature or interfacial structures that are difficult to access in bulk may offer such catalytically active surfaces. We report here that the suboxide Zr3O, which is formed at Zr−ZrO2 interfaces but does not appear in the experimental Zr−O phase diagram exhibits outstanding oxygen reduction reaction (ORR) performance surpassing that of benchmark Pt/C and most transition metal‐based catalysts. Addition of Fe3C nanoparticles to give a Zr−Zr3O−Fe3C/NC catalyst (NC=nitrogen‐doped carbon) gives a half‐wave potential (E1/2) of 0.914 V, outperforming Pt/C and showing only a 3 mV decrease after 20,000 electrochemical cycles. A zinc‐air battery (ZAB) using this cathode material has a high power density of 241.1 mW cm−2 and remains stable for over 50 days of continuous cycling, demonstrating potential for practical applications. Zr3O demonstrates that interfacial or other phases that are difficult to stabilize may offer new directions for the discovery of high‐performance electrocatalysts.
Nichtkovalente Organokatalyse mit Halogen‐, Chalkogen‐, Pniktogen‐ und Tetrelbrücken: neuere Entwicklungen
Authors: Jovanovic Dragana , Poliyodath Mohanan Meghana , Huber Stefan M.
Published: May 2024

Die Anwendung nichtkovalenter Wechselwirkungen, welche auf elektrophilen Halogen‐, Chalkogen‐, Pniktogen‐ oder Tetrelzentren beruhen, hat in der Organokatalyse deutlich an Aufmerksamkeit gewonnen. Wir geben hier einen Überblick über die wichtigsten Entwicklungen der letzten Jahre, mit einem Fokus auf experimentellen Studien und auf Katalysatoren, die über nicht‐transiente derartige Welchselwirkungen agieren.