Singlet Oxygen Generation on Porous Superhydrophobic Surfaces: Effect of Gas Flow and Sensitizer Wetting on Trapping Efficiency

We describe physical-organic studies of singlet oxygen generation and transport into an aqueous solution supported on superhydrophobic surfaces on which silicon–phthalocyanine (Pc) particles are immobilized. Singlet oxygen (1O2) was trapped by a water-soluble anthracene compound and monitored in situ using a UV–vis spectrometer. When oxygen flows through the porous superhydrophobic surface, singlet oxygen generated in the plastron (i.e., the gas layer beneath the liquid) is transported into the solution within gas bubbles, thereby increasing the liquid–gas surface area over which singlet oxygen can be trapped. Higher photooxidation rates were achieved in flowing oxygen, as compared to when the gas in the plastron was static. Superhydrophobic surfaces were also synthesized so that the Pc particles were located in contact with, or isolated from, the aqueous solution to evaluate the relative effectiveness of singlet oxygen generated in solution and the gas phase, respectively; singlet oxygen generated on particles wetted by the solution was trapped more efficiently than singlet oxygen generated in the plastron, even in the presence of flowing oxygen gas. A mechanism is proposed that explains how Pc particle wetting, plastron gas composition and flow rate as well as gas saturation of the aqueous solution affect singlet oxygen trapping efficiency. These stable superhydrophobic surfaces, which can physically isolate the photosensitizer particles from the solution may be of practical importance for delivering singlet oxygen for water purification and medical devices

Superhydrophobic surfaces as a source of airborne singlet oxygen through free space for photodynamic therapy

A superhydrophobic (SH) sandwich system has been developed to enable "contact-free" airborne singlet oxygen (1O2) delivery to a water droplet. The contact-free feature means that the sensitizer is physically separated from the droplet, which presents opportunities for photodynamic therapy (PDT). Trapping of airborne 1O2 in a H2O droplet residing on a lower SH surface was monitored with 9,10-anthracene dipropionate dianion by varying distances to an upper 1O2-generating surface. Short distances of 20 μm efficiently delivered airborne 1O2 to the droplet in single-digit picomolar steady-state concentrations. Delivery decreases linearly with distance, but 50% of the 1O2 steady-state concentration is trapped at a distance of 300 μm from the generating surface. The 1270 nm luminescence intensity was measured within the SH sandwich system, confirming the presence of airborne 1O2. Physical quenching of 1O2 to ground-state 3O2 by the water droplet itself and both physical and chemical quenching of 1O2 by the water droplet containing the trap 9,10-anthracene dipropionate dianion are observed. Unlike a majority of work in the field of PDT with dissolved sensitizers, where 1O2 diffuses short (hundreds of nanometers) distances, we show the delivery of airborne 1O2 via a superhydrophobic surface is effective through air in tenths of millimeters distances to oxidize an organic compound in water. Our results provide not only potential relevance to PDT but also surface bacterial inactivation processes.Fil: Aebisher, David. University Of Rzeszow; PoloniaFil: Bartusik-Aebisher, Dorota. University Of Rzeszow; PoloniaFil: Belh, Sarah J.. City University of New York; Estados UnidosFil: Ghosh, Goutam. City University of New York; Estados UnidosFil: Durantini, Andres Matías. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; ArgentinaFil: Liu, Yang. City University of New York; Estados UnidosFil: Xu, QianFeng. City University of New York; Estados UnidosFil: Lyons, Alan M.. City University of New York; Estados UnidosFil: Greer, Alexander. City University of New York; Estados Unido

Projections of Global Drought and Their Climate Drivers Using CMIP6 Global Climate Models

Due to the complex coupling between drought and climatic factors, the future drought conditions that might occur under climate change is still unclear. In this research, we used the daily SPEI algorithm to project global drought conditions during 2016–2100 based on the data from phase 6 of the Coupled Model Intercomparison Project (CMIP6). We also employed partial correlation analysis to explore the influence of climate factors on drought. Our analyses show the following: (1) Drought conditions projected by CMIP6 under different models are similar; however, they can vary widely across regions. (2) According to the MK trend test, drought conditions in most regions around the world are expected to become increasingly severe in the future, and this trend is significant. (3) Based on the results of the partial correlation analysis results, it is understood that drought events in most regions worldwide are primarily driven by precipitation. This study contributes to the discussion of projecting future drought conditions and expands the application by utilizing the state−of−the−art CMIP6 climate models and scenarios.Highligh

The modification and application of Sewage Sludge based in heterogeneous Fenton-like system

In this study, dewatered domestic sewage sludge of moisture content of 65.6% was used as a pore-forming agent to sinter Ceramics with kaolin clay, coal ash and sodium silicate at 1050-1100 oC for 20 min. The weight percentage of sludge of total dried solids was 60% with pore rate >45% and compressive >20 MPa. The Ceramics could be used as catalysts in heterogeneous Fenton-like system to treat phenol wastewater through modification by FeSO4 solution. After reaction with ceramics catalyst for 2.5 h, phenol removal of the wastewater could reach 99.87% from 100 mg/L to 0.13 mg/L and the COD removal is 85.75%. The performance of this catalyst was stable and had no significant in 30d repeat experiments

New measurements reveal a large contribution of nitrogenous molecules to ambient organic aerosol

Nitrogen is a significant element that constitutes ambient organic aerosol. Individual N-containing organic molecules are known to have both natural and anthropogenic sources and implicated in a wide-ranging health and environmental effects. Yet, unlike carbon (C), the total quantity of aerosol organic nitrogen (ON) remains largely unquantified, hindering a quantitative understanding of their major sources and impacts. Here, for the first time, aerosol ON is quantified in hundreds of aerosol filter samples collected from sites of varying urban influence in China using our recently developed method that permits simple, and yet sensitive, simultaneous detection of inorganic and organic nitrogen. Annual average ON concentration was in the range of 0.4-1.4 μg N m-3, representing 17-31% of aerosol total nitrogen. Monte Carlo simulations constrained by paired ON and organic carbon (OC) measurements suggest N-containing organic molecules contributed typically 37-50%, with a 95% confidence interval of [12%, 94%], to ambient organic aerosols. Source apportionment analysis reveals that biomass burning and secondary formation are dominant ON sources, accounting for 21-24% and ~30% of ON, respectively. Primary biological aerosol is also a significant source of ON (7-18%), with its contribution more prominent in non-urban atmospheres. The revelation of the large presence of nitrogenous molecules in atmospheric aerosols implies their role in carbon chemistry has likely been under-appreciated in the past. This new compositional insight, we anticipate, would bring forth a breakthrough in our ability to describe and model organic aerosols and to rethink the focus of studying and modeling OA

An improved global vegetation health index dataset in detecting vegetation drought

Abstract Due to global warming, drought events have become more frequent, which resulted in aggravated crop failures, food shortage, larger and more energetic wildfires, and have seriously affected socio-economic development and agricultural production. In this study, a global long-term (1981–2021), high-resolution (4 km) improved vegetation health index (VHI) dataset integrating climate, vegetation and soil moisture was developed. Based on drought records from the Emergency Event Database, we compared the detection efficiency of the VHI before and after its improvement in the occurrence and scope of observed drought events. The global drought detection efficiency of the improved high-resolution VHI dataset reached values as high as 85%, which is 14% higher than the original VHI dataset. The improved VHI dataset was also more sensitive to mild droughts and more accurate regarding the extent of droughts. This improved dataset can play an important role in long-term drought monitoring but also has the potential to assess the impact of drought on the agricultural, forestry, ecological and environmental sectors

The first high spatial resolution multi-scale daily SPI and SPEI raster dataset for drought monitoring and evaluating over China from 1979 to 2018

ABSTRACTStandardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI), traditionally derived at a monthly scale, are widely used drought indices. To overcome temporal-resolution limitations, we have previously developed and published a well-validated daily SPI/SPEI in situ dataset. Although having a high temporal resolution, this in situ dataset presents low spatial resolution due to the scarcity of stations. Therefore, based on the China Meteorological Forcing Dataset, which is composed of data from more than 1,000 ground-based observation sites and multiple remote sensing grid meteorological dataset, we present the first high spatiotemporal-resolution daily SPI/SPEI raster datasets over China. It spans from 1979 to 2018, with a spatial resolution of 0.1° × 0.1°, a temporal resolution of 1-day, and the timescales of 30-, 90-, and 360-days. Results show that the spatial distributions of drought event characteristics detected by the daily SPI/SPEI are consistent with the monthly SPI/SPEI. The correlation between the daily value of the 12-month scale and the monthly value of SPI/SPEI is the strongest, with linear correlation, Nash-Sutcliffe coefficient, and normalized root mean square error of 0.98, 0.97, and 0.04, respectively. The daily SPI/SPEI is shown to be more sensitive to flash drought than the monthly SPI/SPEI. Our improved SPI/SPEI shows high accuracy and credibility, presenting enhanced results when compared to the monthly SPI/SPEI. The total data volume is up to 150 GB, compressed to 91 GB in Network Common Data Form (NetCDF). It can be available from Figshare (https://doi.org/10.6084/m9.figshare.c.5823533) and ScienceDB (https://doi.org/10.57760/sciencedb.j00076.00103)

Association of chromosomal abnormalities with prenatal exposure to heavy metals: A nested case-control study in high-risk pregnant women in China

Prenatal exposure to heavy metals causes multiple hazards to fetal growth and development. Epidemiological studies on the association between heavy metals and fetal chromosomal abnormalities (CAs) are lacking. We conducted a nested case-control study in a cohort of high-risk pregnant women in China from September 2018 to June 2021. A total of 387 participants were diagnosed with fetal CAs in the case group and 699 were diagnosed with a normal karyotype in the control group. Amniotic fluid concentrations of 10 metals (barium, cobalt, antimony, manganese, ferrum, copper, selenium, strontium, vanadium, and chromium) were measured using inductively coupled plasma-mass spectrometry. We applied quantile g-computation and weighted quantile sum regression to assess the overall effect of metal mixtures and identify metals with significant weight. Logistic and Poisson regression analyses were used to estimate the effects of metals on CAs and CAs subtypes. Our results showed that the metal mixture concentrations were positively associated with the risk of fetal CAs. In adjusted logistic models, Sb was associated with fetal CAs (OR=1.15, 95% CI: 1.02–1.30), and revealed a linear dose-response relationship between Sb level and the risk of fetal CAs. Additionally, the exploratory analysis revealed that Sb levels were associated with Klinefelter syndrome (OR=1.452, 95% CI: 1.063–1.984) and Turner syndrome (OR=1.698; 95% CI,1.048–2.751). Our study revealed that metal mixtures are associated with a higher risk of fetal CAs and that this association may be driven primarily by Sb. Moreover, we provide a genetic perspective on the effects of heavy metals on sexual development in humans

High-Precision Dispensing of Nanoliter Biofluids on Glass Pedestal Arrays for Ultrasensitive Biomolecule Detection

Precise dispensing of nanoliter droplets is necessary for the development of sensitive and accurate assays, especially when the availability of the source solution is limited. Conventional approaches are limited by imprecise positioning, large shear forces, surface tension effects, and high costs. To address the need for precise and economical dispensing of nanoliter volumes, we developed a new approach where the dispensed volume is dependent on the size and shape of defined surface features, thus freeing the dispensing process from pumps and fine-gauge needles requiring accurate positioning. The surface we fabricated, called a nanoliter droplet virtual well microplate (nVWP), achieves high-precision dispensing (better than ±0.5 nL or ±1.6% at 32 nL) of 20–40 nL droplets using a small source drop (3–10 μL) on isolated hydrophilic glass pedestals (500 μm on a side) bonded to arrays of polydimethylsiloxane conical posts. The sharp 90° edge of the glass pedestal pins the solid–liquid–vapor triple contact line (TCL), averting the wetting of the glass sidewalls while the fluid is prevented from receding from the edge. This edge creates a sufficiently large energy barrier such that microliter water droplets can be poised on the glass pedestals, exhibiting contact angles greater >150°. This approach relieves the stringent mechanical alignment tolerances required for conventional dispensing techniques, shifting the control of dispensed volume to the area circumscribed by the glass edge. The effects of glass surface chemistry and dispense velocity on droplet volume were studied using optical microscopy and high-speed video. Functionalization of the glass pedestal surface enabled the selective adsorption of specific peptides and proteins from synthetic and natural biomolecule mixtures, such as venom. We further demonstrate how the nVWP dispensing platform can be used for a variety of assays, including sensitive detection of proteins and peptides by fluorescence microscopy or MALDI-TOF