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1.
J Arthroplasty ; 39(4): 884-890, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37858710

RESUMO

BACKGROUND: This prospective study aimed to investigate the influence of patellar position (ie, eversion, lateralization, and reduction) on medial and lateral gap measurements during total knee arthroplasty (TKA) in both cruciate-retaining (CR) and posterior-stabilized (PS) TKA designs. METHODS: The present work analyzed 50 knees with primary osteoarthritis that underwent TKA between July and November 2019. Medial and lateral gaps were measured at different knee flexion angles (0°, 45°, 90°, and 120°) in 3 patellar positions after sequentially inserting CR type and PS type trial component in the same knee. RESULTS: In CR TKA, medial gaps in patellar reduction showed significantly smaller gaps at 90° and 120° of knee flexion compared to those in eversion and lateralization (P < .001). Lateral gaps in patellar reduction were also significantly larger than those in eversion and lateralization (P < .001). The mediolateral gap difference in patellar reduction was significantly greater at all flexion angles compared to those in eversion and lateralization (P < .001). In PS TKA, similar patterns were observed for medial gaps, lateral gaps, and mediolateral gap differences (P < .001). CONCLUSIONS: The ligament balancing with the patella everted or subluxed may lead to an overly tight medial gap and/or loose lateral gap in the knee with a closed arthrotomy, which has potential consequences for knee function in both CR and PS TKA designs. The results of this study highlight the importance of considering patellar position to ensure optimal soft-tissue balance and joint stability in TKA.


Assuntos
Artroplastia do Joelho , Prótese do Joelho , Osteoartrite do Joelho , Humanos , Artroplastia do Joelho/métodos , Patela/cirurgia , Estudos Prospectivos , Osteoartrite do Joelho/cirurgia , Articulação do Joelho/cirurgia , Amplitude de Movimento Articular , Fenômenos Biomecânicos
2.
Nano Lett ; 23(24): 11578-11585, 2023 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-38051017

RESUMO

We report the growth of high-quality GaN epitaxial thin films on graphene-coated c-sapphire substrates using pulsed-mode metalorganic vapor-phase epitaxy, together with the fabrication of freestanding GaN films by simple mechanical exfoliation for transferable light-emitting diodes (LEDs). High-quality GaN films grown on the graphene-coated sapphire substrates were easily lifted off by using thermal release tape and transferred onto foreign substrates. Furthermore, we revealed that the pulsed operation of ammonia flow during GaN growth was a critical factor for the fabrication of high-quality freestanding GaN films. These films, exhibiting excellent single crystallinity, were utilized to fabricate transferable GaN LEDs by heteroepitaxially growing InxGa1-xN/GaN multiple quantum wells and a p-GaN layer on the GaN films, showing their potential application in advanced optoelectronic devices.

3.
Environ Res ; 239(Pt 1): 117217, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-37775002

RESUMO

Marine organic aerosols play crucial roles in global climatic systems. However, their chemical properties and relationships with various potential organic sources still need clarification. This study employed high-resolution mass spectrometry to investigate the identity, origin, and transportation of organic aerosols in pristine Antarctic environments (King Sejong Station; 62.2°S, 58.8°W), where complex ocean-cryosphere-atmosphere interactions occur. First, we classified the aerosol samples into three clusters based on their air mass transport history. Next, we investigated the relationship between organic aerosols and their potential sources, including organic matter dissolved in the open ocean, coastal waters, and runoff waters. Cluster 1 (C1), in which the aerosols mainly originated from the open ocean area (i.e., pelagic zone-influenced), exhibited a higher abundance of lipid-like and protein-like organic aerosols than cluster 3 (C3), with ratios 1.8- and 1.6-times higher, respectively. In contrast, C3, characterized by longer air mass retention over sea ice and land areas (i.e., inshore-influenced), had higher lignin- and condensed aromatic structures (CAS)-like organic aerosols by 2.2- and 3.4-times compared to C1. Cluster 2 (C2) has intermediate characteristics between C1 and C3 concerning the chemical properties of the aerosols and air mass travel history. Notably, the chemical properties of the aerosols assigned to C1 are closely related to those of phytoplankton-derived organics enriched in the open ocean. In contrast, those of C3 are comparable to those of terrestrial plant-derived organics enriched in coastal and runoff waters. These findings help evaluate the source-dependent properties of organic aerosols in changing Antarctic environment.


Assuntos
Atmosfera , Camada de Gelo , Regiões Antárticas , Aerossóis , Lignina
4.
Arch Orthop Trauma Surg ; 143(2): 591-602, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34345937

RESUMO

We report the long-term results of Bernese periacetabular osteotomy using a dual approach in hip dysplasia. Fifty-three hips (49 patients, mean age 39.9 years: 13-62 years; bilateral hips: four patients) that underwent periacetabular osteotomy using a dual approach (combined Smith-Peterson and Kocher-Langenbeck techniques) between May 1997 and December 2005 were analyzed in this study. The clinical and radiologic outcomes and complications were analyzed and the final survival rates of the operated hips were investigated with survival analysis curves. Forty-nine hips survived until the final follow-up without arthroplasty, and four hips underwent arthroplasty. The average follow-up period was 11.5 years (8-16 years). The pain visual analogue scale improved from 6.3 to 1.1, while the Harris hip score improved from 61.9 to 91.1. Radiologic findings showed that all cases showed improvements in the center edge angle, acetabular angle, acetabular depth, and femoral head coverage. Two patients underwent intraarticular osteotomy due to a complication, and one patient underwent additional osteotomy due to an under-correction. Three cases showed an asymptomatic nonunion of the superior pubic ramus osteotomy site. One patient developed an avulsion fracture of the anterior superior iliac spine, and none of the cases had an infection or permanent neurologic damage. Kaplan-Meier analysis revealed that the 10-year survival rate was 93% (95% confidence interval [CI] 81-98%) with arthroplasty as the endpoint and 86% (95% CI 70-91%) with the progression of osteoarthritis based on Tönnis osteoarthritis rating as the endpoint. Based on the outcomes of a long-term follow-up of more than 10 years on average, Bernese periacetabular osteotomy via a dual approach was found to be a satisfactory method for lowering the incidence of complications while preserving hips.


Assuntos
Luxação Congênita de Quadril , Luxação do Quadril , Osteoartrite do Quadril , Humanos , Adulto , Luxação do Quadril/cirurgia , Resultado do Tratamento , Estudos Retrospectivos , Luxação Congênita de Quadril/cirurgia , Luxação Congênita de Quadril/complicações , Acetábulo/cirurgia , Osteoartrite do Quadril/cirurgia , Osteotomia/métodos
5.
Microb Ecol ; 81(3): 579-591, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33067657

RESUMO

To understand bacterial biogeography in response to the hydrographic impact of climate change derived from the Arctic glacier melting, we surveyed bacterial diversity and community composition using bacterial 16S rRNA gene metabarcoding in the seawaters of Kongsfjorden, Svalbard, during summer 2016. In the present study, bacterial biogeography in the Kongsfjorden seawaters showed distinct habitat patterns according to water mass classification and habitat transition between Atlantic and fjord surface waters. Moreover, we estimated phylogenetic diversity of bacterial communities using the net relatedness, nearest taxon, and beta nearest taxon indices. We found the influence of freshwater input from glacier melting in shaping bacterial assemblage composition through the stochastic model. We further evaluated bacterial contributions to phytoplankton-derived dimethylsulfoniopropionate (DMSP) using a quantitative PCR (qPCR) measurement with demethylation (dmdA) and cleavage (dddP) genes of two fundamentally different processes. Our qPCR results imply that bacterial DMSP degradation follows the Atlantic inflow during summer in Kongsfjorden. These findings suggest that the Atlantic inflow and glacial melting influence bacterial community composition and assembly processes and thus affect the degradation of phytoplankton-derived organic matter in an Arctic fjord.


Assuntos
Estuários , Camada de Gelo , Regiões Árticas , Filogenia , RNA Ribossômico 16S/genética , Estações do Ano
6.
Environ Sci Technol ; 53(15): 8621-8630, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31310508

RESUMO

The sources of primary and secondary aerosols in the Arctic are still poorly known. A number of surface seawater samples-with varying degrees of Arctic riverine and sea ice influences-were used in a sea spray generation chamber to test them for their potential to produce sea spray aerosols (SSA) and cloud condensation nuclei (CCN). Our interdisciplinary data showed that both sea salt and organic matter (OM) significantly influenced the SSA production. The number concentration of SSA in the coastal samples was negatively correlated with salinity and positively correlated with a number of OM tracers, including dissolved and chromophoric organic carbon (DOC, CDOM), marine microgels and chlorophyll a (Chl-a) but not for viral and bacterial abundances; indicating that OM of riverine origin enhances primary aerosol production. When all samples were considered, transparent exopolymer particles (TEP) were found to be the best indicator correlating positively with the ratio number concentration of SSA/salinity. CCN efficiency was not observed to differ between the SSA from the various samples, despite differences in organic characteristics. It is suggested that the large amount of freshwater from river runoff have a substantial impact on primary aerosols production mechanisms, possibly affecting the cloud radiative forcing.


Assuntos
Clorofila A , Água do Mar , Aerossóis , Regiões Árticas , Rios
7.
Am J Hum Genet ; 96(2): 266-74, 2015 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-25620203

RESUMO

Singleton-Merten syndrome (SMS) is an autosomal-dominant multi-system disorder characterized by dental dysplasia, aortic calcification, skeletal abnormalities, glaucoma, psoriasis, and other conditions. Despite an apparent autosomal-dominant pattern of inheritance, the genetic background of SMS and information about its phenotypic heterogeneity remain unknown. Recently, we found a family affected by glaucoma, aortic calcification, and skeletal abnormalities. Unlike subjects with classic SMS, affected individuals showed normal dentition, suggesting atypical SMS. To identify genetic causes of the disease, we performed exome sequencing in this family and identified a variant (c.1118A>C [p.Glu373Ala]) of DDX58, whose protein product is also known as RIG-I. Further analysis of DDX58 in 100 individuals with congenital glaucoma identified another variant (c.803G>T [p.Cys268Phe]) in a family who harbored neither dental anomalies nor aortic calcification but who suffered from glaucoma and skeletal abnormalities. Cys268 and Glu373 residues of DDX58 belong to ATP-binding motifs I and II, respectively, and these residues are predicted to be located closer to the ADP and RNA molecules than other nonpathogenic missense variants by protein structure analysis. Functional assays revealed that DDX58 alterations confer constitutive activation and thus lead to increased interferon (IFN) activity and IFN-stimulated gene expression. In addition, when we transduced primary human trabecular meshwork cells with c.803G>T (p.Cys268Phe) and c.1118A>C (p.Glu373Ala) mutants, cytopathic effects and a significant decrease in cell number were observed. Taken together, our results demonstrate that DDX58 mutations cause atypical SMS manifesting with variable expression of glaucoma, aortic calcification, and skeletal abnormalities without dental anomalies.


Assuntos
Doenças da Aorta/genética , RNA Helicases DEAD-box/genética , Hipoplasia do Esmalte Dentário/genética , Glaucoma/genética , Metacarpo/anormalidades , Modelos Moleculares , Doenças Musculares/genética , Odontodisplasia/genética , Osteoporose/genética , Calcificação Vascular/genética , Adulto , Doenças da Aorta/patologia , Sequência de Bases , Células Cultivadas , Pré-Escolar , Proteína DEAD-box 58 , RNA Helicases DEAD-box/química , Hipoplasia do Esmalte Dentário/patologia , Exoma/genética , Feminino , Genes Dominantes/genética , Humanos , Masculino , Metacarpo/patologia , Dados de Sequência Molecular , Doenças Musculares/patologia , Anormalidades Musculoesqueléticas/diagnóstico por imagem , Anormalidades Musculoesqueléticas/genética , Mutação de Sentido Incorreto/genética , Odontodisplasia/diagnóstico por imagem , Odontodisplasia/patologia , Osteoporose/patologia , Linhagem , Polimorfismo de Nucleotídeo Único/genética , Radiografia , Receptores Imunológicos , Análise de Sequência de DNA , Calcificação Vascular/patologia
8.
J Nanosci Nanotechnol ; 18(2): 1266-1269, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29448571

RESUMO

The electrocatalytic stability of tin (Sn) nanoparticle for electrochemical reduction of CO2 to formate was measured using an H-type cell during electrolysis for 40 h. The Faradaic efficiency (FE) and partial current density (PCD) of formate formation reduced as much as 10% and 13% of the maximum values, respectively. To elucidate the decrease in FE and PCD, the changes in the morphology, chemical composition, the crystalline structure were investigated. The spherical Sn nanoparticles were pulverized after electrolysis. Furthermore, the crystal structure of the fresh Sn electrocatalyst was collapsed and changed into amorphous phase after 40 h electrolysis. The decrease in FE and PCD of formate production on the Sn/CFP electrode could be mainly originated from the reduction of the SnOx to Sn on the cathode surface during electrolysis.

9.
J Ultrasound Med ; 37(6): 1555-1564, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29159856

RESUMO

Sonography is conventionally used to diagnose fractures by identifying cortical discontinuity of the bone. In this study, fracture sonography in addition to color Doppler and dynamic scanning was performed in settings with limited or no access to radiography. We describe 5 cases of ankle and foot fractures with the use of sonography to identify changes in the fractured site. The width of the fracture space increased on dynamic scanning, and the Doppler signals were generated inside the fracture space on dynamic scanning. In conclusion, color Doppler sonography accompanied by dynamic scanning is a useful adjunctive diagnostic tool in addition to previously described sonographic fracture findings.


Assuntos
Traumatismos do Tornozelo/diagnóstico por imagem , Traumatismos do Pé/diagnóstico por imagem , Fraturas Ósseas/diagnóstico por imagem , Ultrassonografia Doppler em Cores/métodos , Idoso , Tornozelo/diagnóstico por imagem , Feminino , Pé/diagnóstico por imagem , Humanos , Pessoa de Meia-Idade , Estudos Retrospectivos
10.
Sensors (Basel) ; 18(7)2018 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-30011862

RESUMO

Smart materials such as piezoelectric transducers can be used for monitoring the health of building structures. In this study, a structural health monitoring technique known as the electromechanical impedance (EMI) method is investigated. Although the EMI method has the advantage of using a single piezoelectric patch that acts both as the actuator and as the sensor, there are still many issues to be addressed. To further understand the problem, the performance of the EMI method on a structure subjected to progressive damage at different resonance frequency ranges and peak amplitudes was investigated using three different statistical metrics: root-mean-square deviation (RMSD), mean absolute percentage deviation (MAPD) and correlation coefficient deviation (CCD). Metal plates were used throughout the study. The results acquired could be used to further understand the damage identification performance of the EMI method.

11.
Asian-Australas J Anim Sci ; 31(11): 1766-1772, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29642668

RESUMO

OBJECTIVE: This experiment was to investigate the effect of increasing levels of apparent metabolizable energy (AMEn) on the laying performance, egg quality, blood parameters, blood biochemistry, intestinal morphology, and apparent total tract digestibility (ATTD) of energy and nutrients in diets fed to laying hens. METHODS: A total of three-hundred twenty 33-week-old Hy-Line Brown laying hens (Gallus domesticus) were evenly assigned to four experimental diets of 2,750, 2,850, 2,950, and 3,050 kcal AMEn/kg in pens with floors covered with deep litter of rice hulls. There were four replicates of each treatment, each consisting of 20 birds in a pen. RESULTS: AMEn intake was increased (linear, p<0.05) with inclusion level of AMEn in diets increased. Feed intake and feed conversion ratio were improved (linear, p<0.01), but hen-day egg production tended to be increased with an increasing level of AMEn in diets. During the experiment, leukocyte concentration and blood biochemistry (total cholesterol, triglyceride, glucose, total protein, calcium, asparate aminotransferase, and alanine transferase were not influenced by increasing level of AMEn in diets. Gross energy and ether extract were increased (linear, p<0.01) as the inclusion level of AMEn in diets increased. CONCLUSION: Laying hens fed high AMEn diet (i.e., 3,050 kcal/kg in the current experiment) tended to overconsume energy with a positive effect on feed intake, feed conversion ratio, nutrient digestibility, and intestinal morphology but not on egg production and egg mass.

12.
Angew Chem Int Ed Engl ; 57(23): 6883-6887, 2018 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-29660257

RESUMO

Electrochemical reduction of carbon dioxide (CO2 ) into value-added chemicals is a promising strategy to reduce CO2 emission and mitigate climate change. One of the most serious problems in electrocatalytic CO2 reduction (CO2 R) is the low solubility of CO2 in an aqueous electrolyte, which significantly limits the cathodic reaction rate. This paper proposes a facile method of catholyte-free electrocatalytic CO2 reduction to avoid the solubility limitation using commercial tin nanoparticles as a cathode catalyst. Interestingly, as the reaction temperature rises from 303 K to 363 K, the partial current density (PCD) of formate improves more than two times with 52.9 mA cm-2 , despite the decrease in CO2 solubility. Furthermore, a significantly high formate concentration of 41.5 g L-1 is obtained as a one-path product at 343 K with high PCD (51.7 mA cm-2 ) and high Faradaic efficiency (93.3 %) via continuous operation in a full flow cell at a low cell voltage of 2.2 V.

13.
J Phys Ther Sci ; 28(4): 1194-8, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27190452

RESUMO

[Purpose] The aim of this study was to investigate the impact of a circuit training program on the walking and balance abilities of stroke patients using an up-to-date walking analysis device. [Subjects and Methods] The subjects of this study were 12 adults who were diagnosed with stroke. Evaluation was conducted using the Smart Step test for walking ability; (BBS) for balance ability; and the Timed Up and Go test (TUG) for functional mobility and movement ability. The 12 stroke patients were randomly recruited and divided into two groups; an experimental group which performed circuit training with obstacles, and a control group which performed flat gait training). [Results] Between-group comparison of the change in the 10-m walking speed found a statistically significant difference between the two groups. Between-group comparison of the changes in BBS and TUG found statistically significant differences between the two groups. [Conclusion] The circuit training program using obstacles had a positive effect on the gait and balance abilities of the stroke patients.

14.
Anal Chem ; 86(3): 1352-6, 2014 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-24428718

RESUMO

The global sulfur cycle depends primarily on the metabolism of marine microorganisms, which release sulfur gas into the atmosphere and thus affect the redistribution of sulfur globally as well as the earth's climate system. To better quantify sulfur release from the ocean, analysis of the production and distribution of organic sulfur in the ocean is necessary. This report describes a wet-based method for accurate analysis of particulate organic sulfur (POS) in the marine environment. The proposed method overcomes the considerable loss of sulfur (up to 80%) that occurs during analysis using conventional methods involving drying. Use of the wet-based POS extraction procedure in conjunction with a sensitive sulfur analyzer enabled accurate measurements of cellular POS. Data obtained using this method will enable accurate assessment of how rapidly sulfur can transfer among pools. Such information will improve understanding of the role of POS in the oceanic sulfur cycle.

15.
Environ Sci Technol ; 48(9): 4750-6, 2014 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-24724561

RESUMO

Oceanic dimethyl sulfide (DMS) is the enzymatic cleavage product of the algal metabolite dimethylsulfoniopropionate (DMSP) and is the most abundant form of sulfur released into the atmosphere. To investigate the effects of two emerging environmental threats (ocean acidification and warming) on marine DMS production, we performed a large-scale perturbation experiment in a coastal environment. At both ambient temperature and ∼ 2 °C warmer, an increase in partial pressure of carbon dioxide (pCO2) in seawater (160-830 ppmv pCO2) favored the growth of large diatoms, which outcompeted other phytoplankton species in a natural phytoplankton assemblage and reduced the growth rate of smaller, DMSP-rich phototrophic dinoflagellates. This decreased the grazing rate of heterotrophic dinoflagellates (ubiquitous micrograzers), resulting in reduced DMS production via grazing activity. Both the magnitude and sign of the effect of pCO2 on possible future oceanic DMS production were strongly linked to pCO2-induced alterations to the phytoplankton community and the cellular DMSP content of the dominant species and its association with micrograzers.


Assuntos
Dióxido de Carbono/análise , Sulfetos/metabolismo , Zooplâncton/fisiologia , Animais , Atmosfera , Pressão Parcial , Fitoplâncton/metabolismo , Fitoplâncton/fisiologia , Água do Mar/química , Compostos de Sulfônio , Enxofre/metabolismo , Zooplâncton/metabolismo
16.
Mar Pollut Bull ; 201: 116149, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38364527

RESUMO

The Arctic is severely affected by climate change and various forms of environmental pollution. Enriched with nutrients and light-absorbing compounds, the wildfire plume has the potential to affect biological carbon fixation and sequestration within the Arctic Ocean. In this study, we utilized satellite-derived oceanic data (phytoplankton and sea ice) and atmospheric reanalysis products (black carbon, BC, indicative of wildfire impact) to evaluate the effect of the pronounced increase in wildfires from 2019 to 2021 on the East Siberian Sea. During these years, chlorophyll-a levels rose by ∼213 % compared to the previous decadal average, which had notably lower wildfire activities. This increase in chlorophyll-a is attributable to the deposition of nitrogen from the wildfire plume. Concurrently, the period required for sea ice concentration to decrease by 25 % was on average âˆ¼ 10 days shorter than usual. This suggests that BC-induced acceleration of sea ice melting might extend the growing season for phytoplankton.


Assuntos
Incêndios Florestais , Oceanos e Mares , Regiões Árticas , Clorofila , Fitoplâncton , Clorofila A , Carbono , Nutrientes , Camada de Gelo
17.
FEMS Microbiol Ecol ; 100(5)2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38621717

RESUMO

The hydrographic variability in the fjords of Svalbard significantly influences water mass properties, causing distinct patterns of microbial diversity and community composition between surface and subsurface layers. However, surveys on the phytoplankton-associated bacterial communities, pivotal to ecosystem functioning in Arctic fjords, are limited. This study investigated the interactions between phytoplankton and heterotrophic bacterial communities in Svalbard fjord waters through comprehensive eDNA metabarcoding with 16S and 18S rRNA genes. The 16S rRNA sequencing results revealed a homogenous community composition including a few dominant heterotrophic bacteria across fjord waters, whereas 18S rRNA results suggested a spatially diverse eukaryotic plankton distribution. The relative abundances of heterotrophic bacteria showed a depth-wise distribution. By contrast, the dominant phytoplankton populations exhibited variable distributions in surface waters. In the network model, the linkage of phytoplankton (Prasinophytae and Dinophyceae) to heterotrophic bacteria, particularly Actinobacteria, suggested the direct or indirect influence of bacterial contributions on the fate of phytoplankton-derived organic matter. Our prediction of the metabolic pathways for bacterial activity related to phytoplankton-derived organic matter suggested competitive advantages and symbiotic relationships between phytoplankton and heterotrophic bacteria. Our findings provide valuable insights into the response of phytoplankton-bacterial interactions to environmental changes in Arctic fjords.


Assuntos
Bactérias , Processos Heterotróficos , Fitoplâncton , RNA Ribossômico 16S , RNA Ribossômico 18S , Estações do Ano , Fitoplâncton/genética , Fitoplâncton/metabolismo , Regiões Árticas , Bactérias/genética , Bactérias/classificação , Bactérias/metabolismo , Bactérias/isolamento & purificação , RNA Ribossômico 16S/genética , RNA Ribossômico 18S/genética , Código de Barras de DNA Taxonômico , Estuários , Svalbard , Camada de Gelo/microbiologia , Ecossistema , DNA Bacteriano/genética , Biodiversidade , Microbiota/genética
18.
Sci Total Environ ; 879: 163070, 2023 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-36990237

RESUMO

The study of airborne chemical markers is crucial for identifying sources of aerosols, and their atmospheric processes of transport and transformation. The investigation of free amino acids and their differentiation between the L- and D- enantiomers are even more important to understand their sources and atmospheric fate. Aerosol samples were collected with a high-volume sampler with cascade impactor at Mario Zucchelli Station (MZS) on the coast of the Ross Sea (Antarctica) for two summer campaigns (2018/19 and 2019/20). The total mean concentration of free amino acids in PM10 was 4 ± 2 pmol m-3 for both campaigns and most of free amino acids were distributed in fine particles. The coarse mode of airborne D-Alanine and dimethylsufoniopropionate in seawater showed a similar trend during both Antarctic campaigns. Thus, the study of D/L Ala ratio in fine, coarse and PM10 fractions indicated the microlayer as the local source. This paper demonstrated that free amino acids follow the trend of DMS and MSA release occurred in the Ross Sea, confirming their applicability as markers for phytoplankton bloom also in paleoclimatic studies.

19.
Sci Total Environ ; 879: 163020, 2023 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-36965732

RESUMO

In two Icelandic Sea spring blooms (May 2018 and 2019) in the North Atlantic Ocean (62.9-68.0°N, 9.0-28.0°W), chlorophyll-a and dimethylsulfoniopropionate (DMSP) concentrations and DMSP lyase activity (the DMSP-to-dimethyl sulfide (DMS) conversion efficiency) were measured at 67 stations, and the hourly atmospheric DMS mixing ratios were concurrently measured only in May 2019 at Storhofdi on Heimaey Island, located south of Iceland (63.4°N, 20.3°W). The ocean parameters for biology (i.e., chlorophyll-a, DMSP, and DMSP lyase activity) were broadly associated in distribution; however, the statistical significance of the association differed among four ocean domains and also between 2018 and 2019. Specifically, the widespread dominance of Phaeocystis, coccolithophores, and dinoflagellates (all rich in DMSP and high in DMSP lyase activity) across the study area is a compelling indication that variations in DMSP-rich phytoplankton were likely a main cause of the variations in statistical significance. For all the ocean domains defined here, we found that the DMS production capacity (calculated using the exposures of air masses to ocean biology prior to their arrivals at Heimaey and the atmospheric DMS mixing ratios of those air masses at Heimaey) was surprisingly consistent with in situ ocean S data (i.e., DMSP and DMSP lyase activity). Our study shows that the proposed computational approach enabled the detection of changes in DMS production and emission in association with changes in ocean primary producers.


Assuntos
Fitoplâncton , Compostos de Enxofre , Oceano Atlântico , Clorofila , Clorofila A , Islândia , Água do Mar , Sulfetos/análise
20.
Sci Total Environ ; 878: 162969, 2023 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-36958547

RESUMO

Sea spray aerosol (SSA) particles strongly influence clouds and climate but the potential impact of ocean microbiota on SSA fluxes is still a matter of active research. Here-by means of in situ ship-borne measurements-we explore simultaneously molecular-level chemical properties of organic matter (OM) in oceans, sea ice, and the ambient PM2.5 aerosols along a transect of 15,000 km from the western Pacific Ocean (36°13'N) to the Southern Ocean (75°15'S). By means of orbitrap mass spectrometry and optical characteristics, lignin-like material (24 ± 5 %) and humic material (57 ± 8 %) were found to dominate the pelagic Pacific Ocean surface, while intermediate conditions were observed in the Pacific-Southern Ocean waters. In the marine atmosphere, we found a gradient of features in the aerosol: lignin-like material (31 ± 9 %) dominating coastal areas and the pelagic Pacific Ocean, whereas lipid-like (23 ± 16 %) and protein-like (11 ± 10 %) OM controlled the sympagic Southern Ocean (sea ice-influence). The results of this study showed that the OM composition in the ocean, which changes with latitude, affects the OM in aerosol compositions in the atmosphere. This study highlights the importance of the global-scale OM monitoring of the close interaction between the ocean, sea ice, and the atmosphere. Sympagic primary marine aerosols in polar regions must be treated differently from other pelagic-type oceans.

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