Chamber Studies Research Articles

Particulate Nitrosamines and Nitramines in Seoul and Their Major Sources: Primary Emission versus Secondary Formation.

Seven nitrosamines and three nitramines in particulate matter with an aerodynamic diameter of less than or equal to 2.5 μm (PM2.5) collected in 2018 in Seoul, South Korea, were quantified. Annual mean concentrations of the sum of nitrosamines and nitramines were 9.81 ± 18.51 and 1.12 ± 0.70 ng/m3, respectively, and nitrosodi-methylamine (NDMA) and dimethyl-nitramine (DMN) comprised the largest portion of nitrosamines and nitramines, respectively. Statistical analyses such as non-parametric correlation analysis, positive matrix factorization, analysis of covariance, and orthogonal partial least squared discrimination analysis were carried out to identify contribution of the atmospheric reactions in producing NDMA and DMN. In addition, kinetic calculation using reaction information obtained from the previous chamber studies was performed to estimate concentrations of NDMA and DMN that might be produced from the atmospheric reactions. It was concluded that (1) the atmospheric reactions contributed to the concentrations of NDMA more than they did for those of DMN, (2) the contribution of atmospheric reactions to the concentrations of NDMA and DMN was significant due to high NO2 concentrations in winter, and (3) primary emissions predominantly affected the ambient concentrations of NDMA and DMN in spring, summer, and autumn.

Epigenome editing of the CFTR-locus for treatment of cystic fibrosis

BackgroundMechanisms governing the diversity of CFTR gene expression throughout the body are complex. Multiple intronic and distal regulatory elements are responsible for regulating differential CFTR expression across tissues. MethodsDrawing on published data, 18 high-priority genomic regions were identified and interrogated for CFTR-enhancer function using CRISPR/dCas9-based epigenome editing tools. Each region was evaluated by dCas9p300 and dCas9KRAB for its ability to enhance or repress CFTR expression, respectively. ResultsMultiple genomic regions were tested for enhancer activity using CRISPR/dCas9 epigenome editing. dCas9p300 mediates a significant increase in CFTR mRNA levels when targeted to the promoter and a region 44 kb upstream of the transcriptional start site in a CFTR-low expressing cell line. Multiple gRNAs targeting the promoter induced a robust increase in CFTR protein levels. In contrast, dCas9KRAB-mediated repression is much more robust with 10 of the 18 evaluated genomic regions inducing CFTR protein knockdown. To evaluate the therapeutic efficacy of modulating CFTR gene regulation, dCas9p300 was used to induce elevated levels of CFTR from the endogenous locus in ΔF508/ΔF508 human bronchial epithelial cells. Ussing chamber studies demonstrated a synergistic increase in ion transport in response to CRISPR-induced expression of ΔF508 CFTR mRNA along with VX809 treatment. ConclusionsCRISPR/dCas9-based epigenome-editing provides a previously unexplored tool for interrogating CFTR enhancer function. Here, we demonstrate that therapeutic interventions that increase the expression of CFTR may improve the efficacy of CFTR modulators. A better understanding CFTR regulatory mechanisms could uncover novel therapeutic interventions for the development of cystic fibrosis therapies.

Sea Spray Aerosol Chamber Study on Selective Transfer and Enrichment of Free and Combined Amino Acids

Free (FAAs) and combined amino acids (CAAs) were investigated on size-resolved samples of nascent sea spray aerosol (SSA) particles generated during controlled laboratory experiments. Compared to seawater, the amino acids were strongly enriched on the SSA particles. The enrichment factors (EFaer) on submicron SSA particles (EFaer∑FAA: 2.5 × 106 and EFaer∑CAA: 7.9 × 105) were 1–2 orders of magnitude higher than on supermicron ones (EFaer∑FAA: 1.0 × 105 and EFaer∑CAA: 7.3 × 104) and continuously increased toward smaller SSA particles. Molecular-level analysis showed that the more polar the FAAs, the more they are enriched on the SSA particles (especially FAAs with polar acid side chains, e.g., aspartic acid: EFaer of 5.8 × 106). Comparison of the amino acids present on nascent SSA with those present on ambient marine aerosol particles revealed a higher complexity of the amino acids of the nascent SSA, suggesting that atmospheric processes likely reduce the amino acid diversity. In addition, our results highlight that although almost all the amino acids studied are transferred to the atmosphere via bubble bursting under controlled conditions, two amino acids, γ-aminobutyric acid (GABA) and glycine likely have additional sources to the atmosphere. GABA is likely formed on ambient marine submicron aerosol particles to a large extent (35–47% of ∑FAA). Glycine likely originates from long-range transport processes or photochemical reactions, as discussed in the literature; however, our results highlight the potential for a direct oceanic source via bubble bursting (∼20% of ∑FAA). Overall, bubble-bursting-derived total amino acids made up 11–18% of the mass of dissolved organic carbon on the submicron SSA particles.

QTL mapping of resistance to Pseudoperonospora cubensis clade 1, mating type A2, in Cucumis melo.

This is the first identification of QTLs underlying resistance to Pseudoperonospora cubensis in Cucumis melo using a genetically characterized isolate. Pseudoperonospora cubensis, causal organism of cucurbit downy mildew (CDM), is one of the largest threats to cucurbit production in the eastern USA. Currently, no Cucumis melo (melon) cultivars have significant levels of resistance. Additionally, little is understood about the genetic basis of resistance in C. melo. Recombinant inbred lines (RILs; N = 169) generated from a cross between the resistant melon breeding line MR-1 and susceptible cultivar Ananas Yok'neam were phenotyped for CDM resistance in both greenhouse and growth chamber studies. A high-density genetic linkage map with 5,663 binned SNPs created from the RIL population was utilized for QTL mapping. Nine QTLs, including two major QTLs, were associated with CDM resistance. Of the major QTLs, qPcub-10.1 was stable across growth chamber and greenhouse tests, whereas qPcub-8.2 was detected only in growth chamber tests. qPcub-10.1 co-located with an MLO-like protein coding gene, which has been shown to confer resistance to powdery mildew and Phytophthora in other plants. This is the first screening of C. melo germplasm with a genetically characterized P. cubensis isolate.

Contrast-enhanced ultrasound molecular imaging of activated platelets in the progression of atherosclerosis using microbubbles bearing the von Willebrand factor A1 domain.

Platelet-endothelial interactions have been linked to increased inflammatory activation and a prothrombotic state in atherosclerosis. The interaction between von Willebrand factor (vWF)-A1 domain and platelet glycoprotein (GP) Ib/IX plays a significant role in mediating the adhesion of platelets to the injured endothelium. In the present study, contrast-enhanced ultrasound (CEU) molecular imaging with microbubbles bearing the vWF-A1 domain was performed to non-invasively monitor activated platelets on the vascular endothelium in the procession of atherosclerosis. A targeted CEU contrast agent was prepared by attaching the vWF-A1 domain to the shell of microbubbles (MbA1). Rat isotype control antibody was used to produce control (Mbctrl) microbubbles. The binding of MbA1 and Mbctrl to activated platelets was assessed in in vitro flow chamber experiments. Apolipoprotein E (ApoE-/-) deficient mice were studied as a model of atherosclerosis. At 8, 16 and 32 weeks of age, CEU molecular imaging of the proximal aorta with MbA1 and Mbctrl was performed and the imaging signals from microbubbles were quantified. Atherosclerotic lesion severity and platelets on the endothelial surface were assessed by histology and immunohistochemistry. In in vitro flow chamber studies, attachment of MbA1 to activated platelets on culture dishes was significantly greater than that of Mbctrl across a range of shear stresses (P<0.05). The attachment of Mbctrl was sparse and not related to the aggregated platelets. As lesion development progressed in the ApoE-/- mice, molecular imaging of activated platelets demonstrated selective signal enhancement of MbA1 (P<0.05 vs. Mbctrl) at all ages. Selective signal enhancement from MbA1 increased from 8 to 32 weeks of age. Immunohistochemistry for GPIIb revealed the presence of platelets on the endothelial cell surface in each group of ApoE-/- mice and that the degree of platelet deposits was age-dependent. The results of the present study indicated that non-invasive CEU molecular imaging with targeted microbubbles bearing the vWF-A1 domain could not only detect activated platelets on the vascular endothelium but also indicate lesion severity in atherosclerosis.

Characterization of secondary products formed through oxidation of reduced sulfur compounds

Dimethylsulfide (DMS) and dimethyldisulfide (DMDS) are precursors to products, like sulfuric acid and methanesulfonic acid (MSA), which are important to secondary aerosol formation. The formation and yields of particulate MSA and sulfuric acid from the oxidation of reduced sulfur compounds is not well understood. In this study, a 37.5 cubic meter Teflon environmental chamber was utilized to study the oxidation mechanism and aerosol forming potential of DMS and DMDS under dry conditions. Experiments were conducted in both the presence and absence ofNOx, using hydroxyl radical, nitrate radical, as well O(P3) as an oxidant. With initial NOx concentrations of 100 part-per-billion, relatively low for laboratory oxidation experiments, O(P3) dominated oxidation of the reduced sulfur precursor and resulted in aerosol mass yields of greater than 40%. Hydroxyl radical oxidation of DMS and DMDS in the absence of NOx resulted in aerosol yields of 6% and 13%, respectively, while nitrate radical oxidation in the presence of NOx resulted in yields of 8% and less than 1%, respectively. Evidence of sulfuric acid formation was present during all particle-forming experiments, as was evidence of additional unknown sulfur-containing organic particulate. There was no evidence of MSA formation in the gas- or particle-phase throughout this study. The absence of MSA formation in the presence of NOx has not been reported in previous studies and indicates a lack of understanding of the MSA formation mechanism. The observations made during this chamber study diverge from observations made during previous studies conducted under high precursor and NOx concentrations, emphasizing the importance of atmospherically relevant initial conditions.

Volatile organic compound and particulate matter emissions from an ultrasonic essential oil diffuser.

Ultrasonic essential oil diffusers (EODs) are a popular type of indoor scenting source. We performed a chamber study in which we measured the emissions from EODs used with lemon, lavender, eucalyptus, and grapeseed oils. Over the course of 15min, the most abundant VOCs released from lemon, lavender, eucalyptus, and grapeseed oils were 2.6±0.7mg of d-limonene, 3.5±0.4mg of eucalyptol, 1.0±0.1mg of linalyl acetate, and 0.2±0.02mg of linalyl acetate, respectively. Each oil had a unique particulate matter (PM) emission profile in terms of size, number density, and rate. The dominant size ranges of the PM were 10-100nm for lemon oil, 50-100nm for lavender oil, 10-50nm for lemon oil, and above 200nm for grapeseed oil. PM1 emission rates of approximately 2mg/h, 0.1mg/h, and 3mg/h, were observed for lemon, lavender/eucalyptus, and grapeseed oils, respectively. A fivefold increase in PM1 emission was measured when the EOD with eucalyptus oil was filled with tap water as opposed to deionized water. Modeling suggests that reasonable use cases of EODs can contribute substantially to primary and secondary PM in indoor environments, but this potential varies depending on the oil and water types used.

Matrix Metalloproteinase MMP-12 Promotes Macrophage Transmigration Across Intestinal Epithelial Tight Junctions and Increases Severity of Experimental Colitis.

Matrix metalloproteinases [MMPs] play an important role in extracellular matrix regulation during cell growth and wound healing. Increased expression of MMP-12 [human macrophage elastase] has been reported in inflammatory bowel disease [IBD] which is characterised by the loss of epithelial tight junction [TJ] barrier function and an excessive inflammatory response. The aim of this study was to investigate the role of MMP-12 in intestinal TJ barrier function and inflammation. Wild type [WT] and MMP-12-/- mice were subjected to experimental acute or chronic dextran sodium sulphate [DSS] colitis. The mouse colonic permeability was measured in vivo by recycling perfusion of the entire colon and ex vivo by Ussing chamber studies. DSS administration increased colonic permeability through modulation of TJ proteins and also increased MMP-12 expression in the colonic mucosa of WT mice. The acute as well as chronic DSS-induced increase in colonic TJ permeability and the severity of DSS colitis was found to be markedly attenuated in MMP-12-/- mice. The resistance of MMP-12-/- mice to DSS colitis was characterised by reduced macrophage infiltration and transmigration, and reduced basement membrane laminin degradation. Further in vitro and in vivo studies show that macrophage transmigration across the epithelial layer is MMP-12 dependent and the epithelial TJ barrier is compromised during macrophage transmigration. Conclusions: Together, these data demonstrate that MMP-12 mediated degradation of basement membrane laminin, macrophage transmigration, and associated loss of intestinal TJ barrier are key pathogenic factors for intestinal inflammation.

Performance of a Rotating Detonation Rocket Engine with Various Convergent Nozzles and Chamber Lengths

A rotating detonation rocket engine (RDRE) with various convergent nozzles and chamber lengths is investigated. Three hundred hot-fire tests are performed using methane and oxygen ranging from equivalence ratio equaling 0.5–2.5 and total propellant flow up to 0.680 kg/s. For the full-length (76.2 mm) chamber study, three nozzles at contraction ratios ϵc = 1.23, 1.62 and 2.40 are tested. Detonation is exhibited for each geometry at equivalent conditions, with only fuel-rich operability slightly increased for the ϵc = 1.62 and 2.40 nozzles. Despite this, counter-propagation, i.e., opposing wave sets, becomes prevalent with increasing constriction. This is accompanied by higher number of waves, lower wave speed Uwv and higher unsteadiness. Therefore, the most constricted nozzle always has the lowest Uwv. In contrast, engine performance increases with constriction, where thrust and specific impulse linearly increase with ϵc for equivalent conditions, with a 27% maximum increase. Additionally, two half-length (38.1 mm) chambers are studied including a straight chamber and ϵc = 2.40 nozzle; these shortened geometries show equal performance to their longer equivalent. Furthermore, the existence of counter-propagation is minimized. Accompanying high-fidelity simulations and injection recovery analyses describe underlying injection physics driving chamber wave dynamics, suggesting the physical throat/injector interaction influences counter-propagation.

New Particle Formation and Growth from Dimethyl Sulfide Oxidation by Hydroxyl Radicals.

Dimethyl sulfide (DMS) is produced by plankton in oceans and constitutes the largest natural emission of sulfur to the atmosphere. In this work, we examine new particle formation from the primary pathway of oxidation of gas-phase DMS by OH radicals. We particularly focus on particle growth and mass yield as studied experimentally under dry conditions using the atmospheric simulation chamber AURA. Experimentally, we show that aerosol mass yields from oxidation of 50–200 ppb of DMS are low (2–7%) and that particle growth rates (8.2–24.4 nm/h) are comparable with ambient observations. An HR-ToF-AMS was calibrated using methanesulfonic acid (MSA) to account for fragments distributed across both the organic and sulfate fragmentation table. AMS-derived chemical compositions revealed that MSA was always more dominant than sulfate in the secondary aerosols formed. Modeling using the Aerosol Dynamics, gas- and particle-phase chemistry kinetic multilayer model for laboratory CHAMber studies (ADCHAM) indicates that the Master Chemical Mechanism gas-phase chemistry alone underestimates experimentally observed particle formation and that DMS multiphase and autoxidation chemistry is needed to explain observations. Based on quantum chemical calculations, we conclude that particle formation from DMS oxidation in the ambient atmosphere will most likely be driven by mixed sulfuric acid/MSA clusters clustering with both amines and ammonia.

δ15N-stable isotope analysis of NH x : An overview on analytical measurements, source sampling and its source apportionment.

Agricultural sources and non-agricultural emissions contribute to gaseous ammonia (NH3) that plays a vital role in severe haze formation. Qualitative and quantitative contributions of these sources to ambient PM2.5 (particulate matter with an aerodynamic equivalent diameter below 2.5 µm) concentrations remains uncertain. Stable nitrogen isotopic composition (δ15N) of NH3 and NH4+ (δ15N(NH3) and δ15N(NH4+), respectively) can yield valuable information about its sources and associated processes. This review provides an overview of the recent progress in analytical techniques for δ15N(NH3) and δ15N(NH4+) measurement, sampling of atmospheric NH3 and NH4+ in the ambient air and their sources signature (e.g., agricultural vs. fossil fuel), and isotope-based source apportionment of NH3 in urban atmosphere. This study highlights that collecting sample that are fully representative of emission sources remains a challenge in fingerprinting δ15N(NH3) values of NH3 emission sources. Furthermore, isotopic fractionation during NH3 gas-to-particle conversion under varying ambient field conditions (e.g., relative humidity, particle pH, temperature) remains unclear, which indicates more field and laboratory studies to validate theoretically predicted isotopic fractionation are required. Thus, this study concludes that lack of refined δ15N(NH3) fingerprints and full understanding of isotopic fractionation during aerosol formation in a laboratory and field conditions is a limitation for isotope-based source apportionment of NH3. More experimental work (in chamber studies) and theoretical estimations in combinations of field verification are necessary in characterizing isotopic fractionation under various environmental and atmospheric neutralization conditions, which would help to better interpret isotopic data and our understanding on NHx (NH3 + NH4+) dynamics in the atmosphere.Electronic Supplementary MaterialSupplementary material is available in the online version of this article at 10.1007/s11783-021-1414-6 and is accessible for authorized users. Supplementary material includes supplementary tables on summary of recent isotope-based source apportionment studies on ambient NH3 derived from δ15N(NH3) values (Table A1); and summary of recent isotope-based source apportionment studies on particulate NH4+ derived from δ15N(NH4+) values (Table A2).

Perennial ryegrass phytotoxicity increases with mesotrione rate and growth‐promoting environmental conditions

AbstractBleaching of young leaf tissue is a common response to the herbicide mesotrione and varies from one application to another. To better elucidate factors that may contribute to perennial ryegrass (Lolium perenne L.) phytotoxicity from mesotrione, studies were conducted at Blacksburg, VA. Continuous field monitoring of temperature, humidity, solar radiation, soil moisture, and leaf wetness was used to elucidate environmental conditions that led to perennial ryegrass injury by mesotrione applied at 0.14 kg a.i. ha−1. The study found that 2 of 17 weekly treatments caused unacceptable perennial ryegrass injury at two field sites. Ten‐day temporal trends prior to mesotrione treatment showed that temperature, for one injury event, and volumetric soil water content, for the other injury event, were exclusively correlated to visually and digitally assessed perennial ryegrass injury. Both instances suggest that alleviation of suboptimal temperature or moisture with more optimal growing conditions influenced the turf injury response. Additional studies in growth chambers showed that carotenoid levels and turf phytotoxicity were strongly temperature dependent and followed a quadratic response with peak injury occurring at perennial ryegrass growth optima. Carotenoid levels decreased and perennial ryegrass injury increased in response to increased mesotrione rate. These data suggest that mesotrione is more likely to injure perennial ryegrass turf when used at higher rates and under conditions of rapid turfgrass growth.

Importance of temperature in evaluating cotton for resistance to Fusarium wilt caused by Fusarium oxysporum f. sp. vasinfectum race 4

AbstractFusarium wilt of cotton (Gossypium spp.) is caused by a soil‐ and seed‐borne fungal pathogen Fusarium oxysporum f. sp. vasinfectum (FOV). Fusarium oxysporum f. sp. vasinfectum race 4 (FOV4) is a significant threat to cotton production in the United States. The effect of temperature and soil on disease symptoms in cultivars with a range of susceptibility to FOV4 was examined in growth chamber trials. Three upland (G. hirsutum L.) and three pima (G. barbadense L.) cultivars were planted in three types of soils (potting mix and farm soils with and without FOV4 preinfestation) and maintained at four constant temperature regimes (20, 23, 26, and 29 °C). After seedling emergence, each pot was inoculated with conidial suspensions of FOV4 and scored for resistance based on disease incidence (DI), foliar disease severity rating (DSR), and mortality rate (MR) at 7, 14, 21, and 28 d post‐inoculation (dpi). The area under the disease progress curve (AUDPC) based on DSR across the four evaluation dpi was also analyzed. Among the six cultivars tested, Pima PHY 841 RF, Pima S‐6, and the uplands Acala 1517‐08 and FM 2334GLT were the most resistant, whereas upland PHY 725 RF and Pima S‐7 were the most susceptible. The genotypic responses to FOV4 were not significantly (P &gt; .05) affected by differences in temperature regime or soil type. Cotton seedlings manifested more severe symptoms and higher mortality when maintained at 23 °C, followed by 20/26 °C and 29 °C in descending order. The mycelial growth rate was greater at 23/26 °C, whereas plants grew slower at 20/23 °C. There were no differences (P &gt; .05) in DI, DSR, MR, and AUDPC between the inoculated farm soil (with no FOV4 preinfestation) and the inoculated FOV4‐preinfested farm soil, suggesting the unnecessity of using the latter in artificial inoculations. However, the potting soil produced higher (P &lt; .05) DI and DSR at 7 and 14 dpi but lower (P &lt; .05) AUDPC. This growth chamber study demonstrated that 23 °C produced the highest DI, severity, and plant death, providing an important piece of information for screening cotton for FOV4 resistance in breeding and FOV4 disease management in cotton production.

Association between exposure to different stone aggregates from asphalt and blood coagulability: A human exposure chamber study.

A large fraction of particulate matter (PM), especially PM10, concentrations are due to non-exhaust emissions, such as road abrasion and wear on tires and brake pads. Concentrating on road abrasion, we aimed to investigate blood coagulability in healthy adults after exposure to two types of stone materials commonly used in asphalt on Norwegian roads. This study followed a randomized, double-blind, cross-over study design. Using an exposure chamber, 24 healthy young volunteers were exposed to aggregates of two different types of rocks and placebo dust: quartz diorite, rhomb porphyry, and lactose (placebo dust). Each exposure session lasted for 4 hours (h), and blood samples were collected before exposure (baseline), 4h post-exposure, and 24h post-exposure to analyse potential changes in the von Willebrand factor (vWF) as well as of fibrinogen, d-dimer, leukocytes, and thrombocytes. The dust concentration in the exposure chamber was measured with real-time instruments and gravimetric samples of total dust, respirable dust, PM10, PM2.5, and ultrafine particles (UFP). The results were analysed using a linear mixed-effect model. Leukocyte blood counts increased post-exposure for all exposure materials; however, none of the increases were statistically significant. The concentration of fibrinogen increased after exposure to quartz diorite, while it decreased after exposures to rhomb porphyry and lactose. Type of material was a statistically significant explanatory variable for the concentration of fibrinogen, with the most significant increase occurring 24h post-exposure to quartz diorite. After exposure to the three materials, vWF decreased. For the thrombocytes, an increase in blood count was observed 24h post-exposure to quartz diorite and rhomb porphyry, with a modest (p=0.09) positive association for quartz diorite. Although the results are limited, we conclude that the different effects observed post-exposure to quartz diorite support considering potential health effects when choosing materials in the production of asphalt.

Numerical study of treatment chambers for single and multi‐stage pulsed electric field systems

Numerical study of treatment chambers for single and multi‐stage pulsed electric field systems

Profiling soil volatile organic compounds after N fertilization in a soil grown with Rosmarinus officinalis

The biogenic volatile organic compounds (BVOCs) emissions from cultivated plants-soil systems and N fertilization's role on these emissions are mostly unknown. This study aimed to elucidate the BVOCs emissions from a plant-soil system receiving N fertilization using Rosmarinus officinalis as a model case study. We put forward the hypothesis that N fertilization changes the BVOCs emissions patterns irrespectively the presence of Rosmarinus officinalis and that the emissions are related to N availability and bacterial abundance. To test our hypothesis, we established a microcosm (glass static chambers) study in a fully randomized design with four treatments: soil (S), soil and plant (S + P), soil and fertilizer (S + F), soil, plant, and fertilizer (S + P + F); using NH4NO3 as N source. BVOCs were sampled from the microcosms, using the static headspace sampling technique with a solid-phase microextraction (SPME) device and analyzed by gas chromatography–mass spectrometry (HS-SPME-GC–MS). Sampling occurred 1, 2, 3, 4, 7, 10, 15, 17, 22, 25, and 31 days after applying the NH4NO3 and besides BVOCs, we measured soil NH4+ and NO3− concentration as well as 16S rRNA bacterial abundance. Time drives a significant portion of the variation in the chemical diversity and quantity of the different VOCs found throughout the experiment (PERMANOVA; R2 = 0.28, p < 0.001); however, this was dependent on the presence of plant and fertilizer leading to a significant interaction (PERMANOVA; R2 = 0.33, p < 0.001). Individual BVOCs emissions were strongly affected by nitrogen fertilization, plant presence and declined during the time. The most dominant BVOCs detected were benzyl alcohol, acetone, toluene, benzaldehyde, and caprolactam. Interestingly, the BVOCs concentration was negatively associated with soil concentration to NH4+, NO3− and total bacterial abundance.

Minimizing Errors in Measured Yields of Particle-Phase Products Formed in Environmental Chamber Reactions: Revisiting the Yields of β-Hydroxynitrates Formed from 1-Alkene + OH/NOx Reactions

Environmental chamber studies are widely used for measuring the yields of reaction products and secondary organic aerosol formed from the oxidation of volatile organic compounds, information that c...

Spatial arrangement of pre-war housing estates in the context of sustainable development goals on the example of the Księże Małe housing estate in Wrocław

The article aims to present the assumptions and a part of the chamber study results conducted on the Księże Małe estate in Wrocław. The starting point for the research was the observation that the pre-war German housing estates were planned in a functional way, with great care for the surroundings of the buildings, as well as with the use of solutions that would now be defined as elements of blue or green infrastructure. Thus, the pre-war spatial arrangement manner is in line with the contemporary postulates of sustainable development and "healthy" cities. However, the functions of green areas and their elements have degraded over time and nowadays it is often possible to read the former planning concept only by means of comparative cartographic studies. The results of the preliminary research confirm that the subsequent housing development transformations were of a degrading nature, and the pre-war character of the building surroundings is illegible for residents and readable in archival materials that have not been elaborated so far. Recalling the memory of the former arrangement method may contribute to project activities in the area of urban adaptation to climate change, and past practices, a model for shaping contemporary urban plans.

Photosynthesis, fluorescence, and biomass responses of white oak seedlings to urban soil and air temperature effects.

Urban forest patches can provide critical ecosystem services and their ability to regenerate native tree species is critical to their sustainability. Little is known about native tree seedling establishment and physiological function in urban ecosystems. This growth chamber study examined the effects of urban soil and air temperatures on white oak (Quercus alba L.) germination, seedling growth, and leaf-level physiology. A split-plot design tested effects of field collected soils from urban and reference forest sites in Baltimore, Maryland, and warm (urban) versus cool (rural) growth chamber temperature regimes. Seedlings were harvested at the end of the 23-week experiment to assess foliar chemistry and biomass allocation. Seed germination was unaffected by treatments and was high in both soil types and temperature regimes. Urban soils supported significantly higher total seedling biomass and had a significant effect on leaf-level physiological parameters, with seedlings grown in urban soils having greater Anet , Vcmax , ETRmax , Jmax , PNUE, gs , Anet /Rd , and PIabs (an integrated chlorophyll fluorescence parameter). PIabs measurements taken throughout the experiment revealed a significant time × temperature interaction effect. Baltimore urban forest patch soils were higher in nutrients than reference soils, but also higher in heavy metals. Despite higher levels of heavy metals, these results demonstrate that urban forest patch soils are able to support robust white oak seedling growth and enhanced seedling physiological parameters. However, interactions with temperature suggest that warming air temperatures may cause seedling stress and reduced growth.

Pyricularia oryzae incites gray leaf spot disease on hard fescue (Festuca brevipila)

AbstractGray leaf spot, caused by the fungal pathogen Pyricularia oryzae, is a widespread and destructive foliar disease of turfgrasses in the United States. Characteristic gray leaf spot disease symptoms were observed on hard fescue (Festuca brevipila Tracey) turf in New Jersey during October 2018. Prior to this observation, P. oryzae had not been documented as a pathogen of F. brevipila. Therefore, this study was conducted to determine if P. oryzae was the cause of the observed gray leaf spot disease symptoms. Morphological assessments and molecular analyses identified fungal isolates as the potential incitant from symptomatic F. brevipila turf as P. oryzae. Two isolates of P. oryzae (D300452 and 181001P12) and two F. brevipila cultivars (‘Beacon’ and ‘Reliant IV’) were used in growth chamber studies to fulfill Koch's postulates for pathogenicity. Inoculations were carried out using conidial suspensions at 4 × 104 conidia ml−1 concentration. Disease symptoms were observed 7 d post‐inoculation for both isolates on both cultivars. Koch's postulates were fulfilled by morphological evaluations and DNA sequencing of the reisolated fungi. This study confirms that P. oryzae is the causal agent of gray leaf spot disease on F. brevipila. Given the historical significance of gray leaf spot disease in other turf species, this study suggests that gray leaf spot could be a major concern for managing F. brevipila turf in the future.