On sulfur core level binding energies in thiol self-assembly and alternative adsorption sites: An experimental and theoretical study.

Characteristic core level binding energies (CLBEs) are regularly used to infer the modes of molecular adsorption: orientation, organization, and dissociation processes. Here, we focus on a largely debated situation regarding CLBEs in the case of chalcogen atom bearing molecules. For a thiol, this concerns the case when the CLBE of a thiolate sulfur at an adsorption site can be interpreted alternatively as due to atomic adsorption of a S atom, resulting from dissociation. Results of an investigation of the characteristics of thiol self-assembled monolayers (SAMs) obtained by vacuum evaporative adsorption are presented along with core level binding energy calculations. Thiol ended SAMs of 1,4-benzenedimethanethiol (BDMT) obtained by evaporation on Au display an unconventional CLBE structure at about 161.25 eV, which is close to a known CLBE of a S atom on Au. Adsorption and CLBE calculations for sulfur atoms and BDMT molecules are reported and allow delineating trends as a function of chemisorption on hollow, bridge, and atop sites and including the presence of adatoms. These calculations suggest that the 161.25 eV peak is due to an alternative adsorption site, which could be associated to an atop configuration. Therefore, this may be an alternative interpretation, different from the one involving the adsorption of atomic sulfur resulting from the dissociation process of the S-C bond. Calculated differences in S(2p) CLBEs for free BDMT molecules, SH group sulfur on top of the SAM, and disulfide are also reported to clarify possible errors in assignments.

Analysis of Pollution Characteristics and Contributions of Firework Burnings in Nanchang during the Spring Festival.

This study investigates the impact of fireworks on air quality during the Spring Festival in Nanchang City, utilizing high-resolution monitoring data from February 7th to 15th, 2021. Significant variations in K+ concentrations were observed, indicating severe air quality impacts. During the most intense discharge event A, K+ concentrations were 20.7 times higher than background levels, with PM2.5 and PM10 levels rising to 3.63 and 3.32 times above the background, respectively. The contribution of fireworks to PM2.5 was determined to be 72.5 ± 25.6%. Sulfate (SO4 2-) and nitrate (NO3 -) concentrations also increased significantly, with Δ[SO4 2- ] and Δ[NO3 - ] accounting for 15.4 ± 18.7% and 10.9 ± 12.3% of PM2.5, respectively. The study highlights the necessity for effective emission control strategies to mitigate the adverse effects of fireworks on urban air quality and public health. Future research should focus on the detailed chemical pathways and long-term impacts of these episodic emissions.

LAL test and RPT for endotoxin detection of CPT-11/DSPE-mPEG2000 nanoformulation: What if traditional methods are not applicable?

Endotoxin detection is an important step in drug characterization. Herein we found that a chemotherapeutic drug nanoformulation composed of irinotecan hydrochloride (CPT-11) and an amphiphilic molecule DSPE-mPEG2000 can interfere with the limulus amebocyte lysate assay (LAL). Furthermore, the rabbit pyrogen test (RPT) results indicated that at a relatively high dosage, the drug irinotecan hydrochloride can induce a hypothermia effect which may render the RPT results ambiguous in determination of the safety of the drug formulation.Our findings demonstrate limitations of endotoxin detection in micellar drugs, and call for the necessity of developing reliable endotoxin detection methods that can overcome the interference of nanomaterials in order to better ensure the drug safety of patients in future pharmaceutical drug development.

Hyperpolization-activated Ca(2+) channels in guard cell plasma membrane are involved in extracellular ATP-promoted stomatal opening in Vicia faba.

Extracellular ATP (eATP) plays essential roles in plant growth, development, and stress tolerance. Extracellular ATP-regulated stomatal movement of Arabidopsis thaliana has been reported. Here, ATP was found to promote stomatal opening of Vicia faba in a dose-dependent manner. Three weakly hydrolysable ATP analogs (adenosine 5'-O-(3-thio) triphosphate (ATPγS), 3'-O-(4-benzoyl) benzoyl adenosine 5'-triphosphate (Bz-ATP) and 2-methylthio-adenosine 5'-triphosphate (2meATP)) showed similar effects, indicating that ATP acts as a signal molecule rather than an energy charger. ADP promoted stomatal opening, while AMP and adenosine did not affect stomatal movement. An ATP-promoted stomatal opening was blocked by the NADPH oxidase inhibitor diphenylene iodonium (DPI), the reductant dithiothreitol (DTT) or the Ca(2+) channel blockers GdCl3 and LaCl3. A hyperpolarization-activated Ca(2+) channel was detected in plasma membrane of guard cell protoplast. Extracellular ATP and weakly hydrolyzable ATP analogs activated this Ca(2+) channel significantly. Extracellular ATP-promoted Ca(2+) channel activation was markedly inhibited by DPI or DTT. These results indicated that eATP may promote stomatal opening via reactive oxygen species that regulate guard cell plasma membrane Ca(2+) channels.