OH and HO₂ radicals chemistry at a suburban site during the EXPLORE-YRD campaign in 2018

The first OH and HO2 radical observation in Yangtze River Delta, one of the four major urban agglomerations in China, was carried out at a suburban site Taizhou in summer 2018 from May to June, aiming to elucidate the atmospheric oxidation capacity in this region. The maximum diurnal averaged OH and HO2 concentrations were 1.0 × 107 cm−3 and 1.1 × 109 cm−3, respectively, which were the second highest HOx (sum of OH and HO2) radical concentrations observed in China. HONO photolysis was the dominant radical primary source, accounting for 42 % of the total radical initiation rate. Other contributions were from carbonyl photolysis (including HCHO, 24 %), O3 photolysis (17 %), alkenes ozonolysis (14 %), and NO3 oxidation (3 %). A chemical box model based on RACM2-LIM1 mechanism could generally reproduce the observed HOx radicals, but systematic discrepancy remained in the afternoon for OH radical, when NO mixing ratio was less than 0.3 ppb. Additional recycling mechanism equivalent to 100 ppt NO was capable to fill the gap. The sum of monoterpenes was on average up to 0.4 ppb during daytime, which was allocated all to α-pinene in the base model. Sensitivity test without monoterpene input showed the modelled OH and HO2 concentrations would increase by 7 % and 4 %, respectively, but modelled RO2 concentration would significantly decrease by 23 %, indicating that monoterpene was an important precursor of RO2 radicals in this study. Consequently, the daily integrated net ozone production would reduce by 6.3 ppb if without monoterpene input, proving the significant role of monoterpene on the photochemical O3 production in this study. Besides, the generally good agreement between observed and modelled HOx concentrations suggested no significant HO2 heterogeneous uptake process during this campaign. Incorporation of HO2 heterogeneous uptake process would worsen the agreement between HOx radical observation and simulation, and the discrepancy would be beyond the measurement-model combined uncertainties using an effective uptake coefficient of 0.2. Finally, the ozone production efficiency (OPE) was only 1.7 in this study, a few folds lower than other studies in (sub)urban environments. The low OPE indicated slow radical propagation rate and short chain length. As a consequence, ozone formation was suppressed by the low NO concentration in this study.

Detection of Excess Presence of 99mTc-MDP Near Injection Site—A Case Report

Nuclear medicine extravasations and prolonged venous stasis may cause poor quality and quantification errors that can affect image interpretation and patient management. Radiopharmaceutical remaining near the administration site means that some portion of the radioactivity is not circulating as required for the prescribed uptake period. This case describes how detection of excess presence of 99mTc-MDP near the injection site enabled the technologist to apply mitigation tactics early in the uptake process. It also suggests that detecting an extravasation or stasis early in the injection process can be important for image interpretation and minimizing radiation dose to tissue.

Aqueous Photochemistry of 2-Oxocarboxylic Acids: Evidence, Mechanisms, and Atmospheric Impact

Atmospheric organic aerosols play a major role in climate, demanding a better understanding of their formation mechanisms by contributing multiphase chemical reactions with the participation of water. The sunlight driven aqueous photochemistry of small 2-oxocarboxylic acids is a potential major source of organic aerosol, which prompted the investigations into the mechanisms of glyoxylic acid and pyruvic acid photochemistry reviewed here. While 2-oxocarboxylic acids can be contained or directly created in the particles, the majorities of these abundant and available molecules are in the gas phase and must first undergo the surface uptake process to react in, and on the surface, of aqueous particles. Thus, the work also reviews the acid-base reaction that occurs when gaseous pyruvic acid meets the interface of aqueous microdroplets, which is contrasted with the same process for acetic acid. This work classifies relevant information needed to understand the photochemistry of aqueous pyruvic acid and glyoxylic acid and motivates future studies based on reports that use novel strategies and methodologies to advance this field.

Adsorptive Removal of Cd(II) Ions from Wastewater Using Maleic Anhydride Nanocellulose

In this study, both pristine cellulose nanocrystalline (CNC) and maleic anhydride functionalized cellulose nanocrystalline (MA-CNC) were prepared from the stems of Eichhornia crassipes weed by the sulfuric acid hydrolysis method. The as-prepared adsorbents were characterized by using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and Brunauer–Emmett–Teller (BET) instruments. These materials were applied for the removal of Cd(II) ions from WW. The uptake mechanism was fixed to both Langmuir and Freundlich adsorption isotherms with a maximum Cd(II) ion uptake capability (qmax) of 75.76 and 215.52 mg g−1 by CNC and MA-CNC adsorbents, respectively. Pseudo-second-order (PSO) kinetic model was well fitted to the uptake process. The adsorbent regeneration study was done after desorption of Cd(II) ions from the adsorbent by HCl washing. Results exhibited that the adsorbent was reused for the removal of Cd(II) ions from real WW after successive 13th cycle.

Mechanistic modeling of pesticide uptake with a 3D plant architecture model

Meaningful assessment of pesticide fate in soils and plants is based on fate models that represent all relevant processes. With mechanistic models, these processes can be simulated based on soil, substance, and plant properties. We present a mechanistic model that simulates pesticide uptake from soil and investigate how it is influenced, depending on the governing uptake process, by root and substance properties and by distributions of the substance and water in the soil profile. A new root solute uptake model based on a lumped version of the Trapp model (Trapp, 2000) was implemented in a coupled version of R-SWMS-ParTrace models for 3-D water flow and solute transport in soil and root systems. Solute uptake was modeled as two individual processes: advection with the transpiration stream and diffusion through the root membrane. We set up the model for a FOCUS scenario used in the European Union (EU) for pesticide registration. Considering a single vertical root and advective uptake only, the root hydraulic properties could be defined so that water and substance uptake and substance fate in soil showed a good agreement with the results of the 1D PEARL model, one of the reference models used in the EU for pesticide registration. Simulations with a complex root system and using root hydraulic parameters reported in the literature predicted larger water uptake from the upper root zone, leading to larger pesticide uptake when pesticides are concentrated in the upper root zone. Dilution of root water concentrations at the top root zone with water with low pesticide concentration taken up from the bottom of the root zone leads to larger uptake of solute when uptake was simulated as a diffusive process. This illustrates the importance of modeling uptake mechanistically and considering root and solute physical and chemical properties, especially when root-zone pesticide concentrations are non-uniform.

Bass Models for EHR, RIS and PACS Diffusion in Finland and Germany

Building on Rogers’ Diffusion of Innovation Theory, Bass models describe the diffusion processes distinguishing between innovation (p) and imitation (q). This study aimed at modelling the uptake of RIS, PACS and EHR systems in Germany and Finland. The Bass models revealed a quick and almost identical uptake process across all three systems for Finland. In contrast, the Bass models mirrored a slower uptake in Germany. Consequently, the Finnish “imitation” coefficients were larger than the German ones. While in Germany almost free market forces were driving the adoption through imitation but without tail wind from policy, the adoption process in Finland was centrally governed. This suggests that the diffusion process in Finland reflected a well-managed roll-out of the systems rather than imitation behaviour. Thus, in order for Bass model coefficients to be understood properly, additional contextual information is required.

Preparation and Characterization of Functionalized Cellulose Nanomaterials (CNMs) for Pb(II) Ions Removal from Wastewater

Due to their remarkable properties, cellulose nanomaterials are emerging materials for wastewater (WW) treatment. In this study, both pristine cellulose nanomaterial (CNM) and sodium periodate modified cellulose nanomaterial (NaIO4-CNM) were prepared from the stem of the Erythrina brucei plant for the removal of Pb(II) ions from WW. As-prepared CNMs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and thermogravimetric analysis with differential thermogravimetry (TGA-DTG) analysis. The as-prepared and characterized CNMs were tested for the removal of Pb(II) ions from secondary run-off wastewater (SERWW). Langmuir and Freundlich adsorption isotherms were certainly fixed to a maximum Pb(II) ions uptake capability (Qmax) of 91.74 and 384.62 mg g−1 by CNM and NaIO4-CNM adsorbents, respectively. The pseudo-second-order (PSO) kinetics model was well fitted to the uptake process. Results revealed that the percentage removal (%R) of Pb(II) ions was decreased by the presence of nitrogen and organic matter, but not affected by the presence of phosphorous in SERWW. Due to its high efficiency, NaIO4-CNM was selected for the regeneration study. The regeneration study was conducted after desorption of Pb(II) ions from the adsorbent by the addition of HCl, and the regenerated sorbent was reused as an adsorbent for at least 13 successive cycles. The results indicated excellent recycling capabilities, and the adsorbent was used as adsorbing material for the removal of Pb(II) ions from SERWW after 13 successive cycles without significant efficient loss.

Review of the hydraulic capacity of urban grate inlet: a global and Latin American perspective

The most recent numerical models of urban drainage allow the integration of runoff from roads with the network of sewer pipes, thus evolving towards a holistic version of the system. A fundamental part of this integration is the capture of stormwater in urban drain inlets. These studies have recently increased, resulting in different methodologies to represent the uptake process and making it difficult to apply unified or general formulations. Therefore, this document intends to be a review of the most representative experimental and numerical studies on the capture of rainwater through grates. In addition, the review includes the proposed methodologies for estimating the flow captured by urban storm drains to define a starting point for new and complementary studies to be carried out by researchers, manufacturers, and operators involved in public drainage service systems. Particularly in Latin America, research on the subject is limited even though it is a highly urbanized region. In this context, this document has an additional interest in presenting a particular analysis of the concept of urban drainage in Latin American cities.

Developmental maturation of the colonic uptake process of the microbiota-generated thiamin pyrophosphate

The water-soluble vitamin B1 is essential for normal human health and physiology. In its main biologically active form, i.e., thiamin pyrophosphate (TPP), the vitamin plays many critical roles in cell metabolism; thus, its deficiency leads to a variety of adverse effects. Humans/mammals obtain vitamin B1 from two exogenous sources: diet and gut microbiota. Considerable amount of the microbiota-generated vitamin B1 exists in the form of TPP, and colonocytes can efficiently absorb this TPP via a high-affinity and specific carrier-mediated mechanism that involves the recently cloned colonic TPP transporter (cTPPT; product of SLC44A4 gene). There is nothing currently known about colonic uptake of TPP during early stages of life, and whether the process undergoes developmental regulation. We addressed this issue using the mouse as animal model. Our results showed that colonic uptake of TPP undergoes developmental up-regulation as the animal moves from the suckling period to weanling and adulthood. This up-regulation in uptake was found to be associated with a parallel induction in level of expression of the cTPPT protein, mRNA and heterologous nuclear RNA (hnRNA), suggesting possible involvement of transcriptional mechanism(s). We also found a parallel up-regulation in level of expression of the two nuclear factors that drive activity of the SLC44A4 promoter (i. e., CREB-1 and Elf-3) with maturation. These results demonstrate, for the first time, that colonic TPP uptake process and cTPPT expression are developmentally up-regulated, and that this up-regulation is likely driven via transcriptional mechanism(s).