Rate coefficients for reactions of OH radicals with CH3D,CH2D2, CHD3, and CD4

Fourier transform infrared (FTIR) smog chamber techniques were used to investigate the atmospheric chemistry of the isotopologues of methane. Relative rate measurements were performed to determine the kinetics of the reaction of the isotopologues of methane with OH radicals in cm³ molecule⁻¹ s⁻¹ units: k(CH₃D + OH) = (5.19 ± 0.90) × 10⁻¹⁵, k(CH₂D₂ + OH) = (4.11 ± 0.74) × 10⁻¹⁵, k(CHD₃ + OH) = (2.14 ± 0.43) × 10⁻¹⁵, and k(CD₄ + OH) = (1.17 ± 0.19) × 10⁻¹⁵ in 700 Torr of air diluent at 296 ± 2 K. Using the determined OH rate coefficients, the atmospheric lifetimes for CH_4–xD_x (x = 1–4) were estimated to be 6.1, 7.7, 14.8, and 27.0 years, respectively. The results are discussed in relation to previous measurements of these rate coefficients.     

Using an electrical potential to reversibly switch surfaces between two states for dynamically controlling cell adhesion

Smart surfaces presenting both antifouling molecules with a charged functional group at their distal end, and molecules that are terminated by RGD peptides for cell adhesion, were fabricated and characterized (see picture). By applying potentials of +300 or -300?mV, the surfaces could be dynamically switched to make the peptide accessible or inaccessible to cells.     

Environmental accounting for the lagoon of Venice and the case of fishing

This paper presents the application of the eMergy evaluation, introduced by H.T. Odum as an efficient methodology of environmental accounting. The results of this analysis are a part of a wider sustainability assessment for the Province of Venice realized in 2003. Within a territorial sustainability analysis, it is necessary to implement an environmental accounting method, which is able: to precisely consider the boundaries of the investigated system (spatial scale); to arbitrarily separate the life of the investigated system into periods (temporal scale); to account for both economic and natural support to a given territorial system in order to implement a sustainable management of resources; to assess all the items supporting the system on the basis of a physical unit that is objective (while the traditional economic evaluation method is based on individual preferences, hence it is subjective). The Province of Venice is a very complex system due, on one hand, to the heavy and consolidated presence of industrial activity since the beginning of the 20th century and, on the other hand, to the principal natural ecosystem which characterizes it: the lagoon, the largest wetland in the Mediterranean Sea. The role of the lagoon, as a provider of resources and services is represented by the analysis of two aspects: the lagoon as an ecosystem on the basis of the evaluation of all flows that cyclically support its biotic activity and the lagoon as a productive system on the basis of the contribution of both natural and "economic" inputs that support human activity. In particular, the case of clam fishing will be presented to put on evidence the importance of natural inputs that are systematically neglected by the traditional accounting methodologies.     

Branched tetrahydrofuran α,α-disubstituted-δ-sugar amino acid scaffolds from branched sugar lactones: a new family of foldamers?

Efficient S_N2 ring closure of open chain trihydroxytriflates—in which the leaving group is on a primary carbon adjacent to a quaternary centre—provides access to tetrahydrofurans with branched carbon chains from branched carbohydrate lactones; the first examples of a new class of branched chain tetrahydrofuran α,α-disubstituted-δ-sugar amino acid scaffolds are described.     

Site-Specific Differences in Proteasome-Dependent Degradation of Monoubiquitinated α-Synuclein

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Analysis of PCBs in soils and sediments by microwave-assisted extraction,headspace-SPME and high resolution gas chromatography with ion-trap tandem mass spectrometry

A procedure for the determination of seven indicator PCBs in soils and sediments using microwave-assisted extraction (MAE) and headspace solid-phase microextraction (HS-SPME) prior to GC-MS/MS is described. Optimization of the HS-SPME was carried out for the most important parameters such as extraction time, sample volume and temperature. The adopted methodology has reduced consumption of organic solvents and analysis runtime. Under the optimized conditions, the method detection limit ranged from 0.6 to 1?ng/g when 5?g of sample was extracted, the precision on real samples ranged from 4 to 21% and the recovery from 69 to 104%. The proposed method, which included the analysis of a certified reference material in its validation procedure, can be extended to several other PCBs and used in the monitoring of soil or sediments for the presence of PCBs.     

Photochemical Bromination of 2,5-Dimethylbenzoic Acid as Key Step of an Improved Alkyne-Functionalized Blue Box Synthesis**

Cyclobis(paraquat-p-phenylene), also known as “blue box”, is a highly electron-deficient macrocycle, widely used as a molecular receptor for small electron-rich molecules. Inserting a reactive functional group onto the molecular structure of this cyclophane is paramount for its inclusion into complex architectures. To this aim, including an alkyne moiety would be ideal, because it can participate in click reactions. However, the synthesis of such alkyne-functionalized cyclophane suffers from several drawbacks: the use of toxic and expensive CCl₄, the need for high-pressure reactors, and overall low yield. We have revised the existing synthesis of this cyclophane derivative bearing an alkyne moiety, to overcome all these limitations. In particular, photochemical radical bromination is adopted to obtain a sensitive intermediate. We demonstrated that the synthesized host molecule can be functionalized via click reactions and take part in radical-radical interactions. Our work makes a key functionalized paraquat macrocycle more accessible, facilitating the development of novel redox-responsive systems.     

Coronaviruses Use ACE2 Monomers as Entry-Receptors

The angiotensin-converting enzyme 2 (ACE2) has been identified as entry receptor on cells enabling binding and infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) via trimeric spike (S) proteins protruding from the viral surface. It has been suggested that trimeric S proteins preferably bind to plasma membrane areas with high concentrations of possibly multimeric ACE2 receptors to achieve a higher binding and infection efficiency. Here we used direct stochastic optical reconstruction microscopy (dSTORM) in combination with different labeling approaches to visualize the distribution and quantify the expression of ACE2 on different cells. Our results reveal that endogenous ACE2 receptors are present as monomers in the plasma membrane with densities of only 1–2 receptors μm⁻². In addition, binding of trimeric S proteins does not induce the formation of ACE2 oligomers in the plasma membrane. Supported by infection studies using vesicular stomatitis virus (VSV) particles bearing S proteins our data demonstrate that a single S protein interaction per virus particle with a monomeric ACE2 receptor is sufficient for infection, which provides SARS-CoV-2 a high infectivity.     

Electrochemiluminescence Bioassays with a Water‐Soluble Luminol Derivative Can Outperform Fluorescence Assays

The most efficient and commonly used electrochemiluminescence (ECL) emitters are luminol, [Ru(bpy)₃]²⁺, and derivatives thereof. Luminol stands out due to its low excitation potential, but applications are limited by its insolubility under physiological conditions. The water‐soluble m‐carboxy luminol was synthesized in 15 % yield and exhibited high solubility under physiological conditions and afforded a four‐fold ECL signal increase (vs. luminol). Entrapment in DNA‐tagged liposomes enabled a DNA assay with a detection limit of 3.2 pmol L^?1, which is 150 times lower than the corresponding fluorescence approach. This remarkable sensitivity gain and the low excitation potential establish m‐carboxy luminol as a superior ECL probe with direct relevance to chemiluminescence and enzymatic bioanalytical approaches.