A direct, visible‐light‐mediated, radical‐cascade addition/sulfonylation/cyclization reaction with DABCO ⋅ (SO2)2 and thianthrenium salts is reported herein. This protocol provides ...operationally‐convenient access to various sulfonated functionalized indole 2,1‐a isoquinolines under mild conditions. This transformation features high functional‐group tolerance, operational ease, and broad substrate scope. Preliminary studies reveal that the method undergoes a radical pathway.
Herein reported is a strategy for constructing vicinal 4°/3° carbons
reductive Cope rearrangement. Substrates have been designed which exhibit Cope rearrangement kinetic barriers of ∼23 kcal mol
with ...isoenergetic favorability (Δ
∼ 0). These fluxional/shape-shifting molecules can be driven forward by chemoselective reduction to useful polyfunctionalized building blocks.
A procedure is presented for characterising the effects of varying finite substrate/ground plane size on the gain properties of microstrip antennas by means of Gaussian process regression (GPR). Two ...kinds of microstrip antenna were considered, namely a probe-fed patch antenna on both thin and thick dielectric substrates, and an L-probe-fed patch on a thick air substrate. CST Microwave Studio was used to generate training and test data for the GPR models. Frontal E and H-plane gain patterns could be predicted with normalised root-mean-square errors (RMSEs) of <1.8% for the thin-substrate probe-fed patch and the L-probe-fed patch; for the thick-substrate probe-fed patch, RMSEs were 2.1 and 2.8% for the two principal plane gain patterns, respectively. Furthermore, the GPR models could predict patterns at least two orders of magnitude faster than it took to obtain them via direct simulation in CST. Such models are expected to be useful in CAD-based environments for rapidly obtaining estimates of substrate/ground-plane size effects on gain characteristics in lieu of time-consuming full-wave simulations.
Worldwide, tuberculosis is the second leading infectious killer and multidrug resistance severely hampers disease control. Mycolic acids are a unique category of lipids that are essential for ...viability, virulence, and persistence of the causative agent, Mycobacterium tuberculosis (Mtb). Therefore, enzymes involved in mycolic acid biosynthesis represent an important class of drug targets. We previously showed that the (3R)‐hydroxyacyl‐ACP dehydratase (HAD) protein HadD is dedicated mainly to the production of ketomycolic acids and plays a determinant role in Mtb biofilm formation and virulence. Here, we discovered that HAD activity requires the formation of a tight heterotetramer between HadD and HadB, a HAD unit encoded by a distinct chromosomal region. Using biochemical, structural, and cell‐based analyses, we showed that HadB is the catalytic subunit, whereas HadD is involved in substrate binding. Based on HadBDMtb crystal structure and substrate‐bound models, we identified determinants of the ultra‐long‐chain lipid substrate specificity and revealed details of structure–function relationship. HadBDMtb unique function is partly due to a wider opening and a higher flexibility of the substrate‐binding crevice in HadD, as well as the drastically truncated central α‐helix of HadD hotdog fold, a feature described for the first time in a HAD enzyme. Taken together, our study shows that HadBDMtb, and not HadD alone, is the biologically relevant functional unit. These results have important implications for designing innovative antivirulence molecules to fight tuberculosis, as they suggest that the target to consider is not an isolated subunit, but the whole HadBD complex.
The ability to detect, identify and quantify bacteria is crucial in clinical diagnostics, environmental testing, food security settings and in microbiology research. Recently, the threat of ...multidrug-resistant bacterial pathogens pushed the global scientific community to develop fast, reliable, specific and affordable methods to detect bacterial species. The use of synthetically modified enzyme substrates is a convenient approach to detect bacteria in a specific, economic and rapid manner. The method is based on the use of specific enzyme substrates for a given bacterial marker enzyme, conjugated to a signalogenic moiety. Following enzymatic reaction, the signalophor is released from the synthetic substrate, generating a specific and measurable signal. Several types of signalophors have been described and are defined by the type of signal they generate, such as chromogenic, fluorogenic, luminogenic, electrogenic and redox. Signalophors are further subdivided into groups based on their solubility in water, which is key in defining their application on solid or liquid media for bacterial culturing. This comprehensive review describes synthetic enzyme substrates and their applications for bacterial detection, showing their mechanism of action and their synthetic routes.
In pursuit of a renewable, inexpensive, sustainable, and compact energy source to replace fossil fuels, solar photovoltaic devices have become an ideal alternative to meet human needs for ...environmentally friendly, affordable, and portable power sources. It is due to their excellent mechanical robustness and outstanding energy conversion efficiency. Concerning the increasing demand for flexible and wearable electronic devices with standalone power sources, much attention has been paid to photovoltaics' flexibility and lightweight developments. Along with high mechanical flexibility and lightweight, flexible photovoltaic devices have the advantages of conformability, bendability, wearability, moldability, and roll‐to‐roll processing into complex shapes that can produce niche products. Emerging solar cells, among other photovoltaic technologies, have been exalted for their high conversion efficiency, low cost, and ease of production, making them a viable new‐generation photovoltaic technology. The main commercialization choice for cutting‐edge solar cells is flexible dye‐sensitized and perovskite solar cells since they can be made using a roll‐to‐roll printing technique and are appropriate for mass manufacturing. More significantly, flexible evolving solar cells may be created on ultrathin and light substrates to fulfill the demands of the developing flexible electronics industry and discover uses that are not possible with traditional photovoltaic technology. In any flexible device, the substrate is a backbone on which further materials rely. A flexible substrate reduces the installation and transportation charges, thereby reducing the system price and increasing power conversion efficiency. In this review, we comprehensively assess relevant materials suitable for making flexible photovoltaic devices. Several flexible substrate materials, including ultra‐thin glass, metal foils, and various types of polymer materials, have been considered. For conducting materials, transparent conducting oxides, metal nanowires/grids, carbon nanomaterials, and conducting polymers have also been comprehended. Progress on various flexible foils, fabrication and stability issues, current challenges, and solutions to those challenges of using conductive polymer substrate is endorsed and reviewed in detail. The originality of this holistic study lies in its ability to offer a thorough overview of recent advancements in flexible dye‐sensitized and perovskite solar cells on polymer substrates, which is conceivable and worthy as a roadmap for future research work.
Modern society is demanding flexible, low‐cost, and lightweight photovoltaic devices, which are essential in a variety of applications ranging from wearable to portable devices. In this regard, this review article describes the principles of solar cells and the recent research progress on flexible substrates for which glass, metal, and polymers are used as substrates to fabricate high‐performance flexible photovoltaic devices.
Pathogenic Escherichia coli poses a serious threat to global public health and is especially dangerous with the increase of antibiotic resistance. β-Glucuronidase (GUS) and some other glycosidases ...can serve as useful biomarkers or indicators for the detection of E. coli. The probes made up of a glycosyl residue (recognition group), a label or reporter group, and a linkage that is generally a direct glycosidic bond, are powerful analytical tools. Upon hydrolysis of the glycosidic linkages by the corresponding glycosidases, these probes irreversibly release detectable labels or reporter molecules. A variety of such glycosidase probes have been developed and applied for the detection of E. coli or the development of various corresponding detection methods. This paper provides an overview of recent advances in this field, covering the development and applications of chromogenic, fluorogenic, luminogenic, and electrochemical glycosidase substrates. The challenges and opportunities in the probe development for detection of E. coli are also discussed.
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