Organothianthrenium salts are a class of compounds containing a positively charged sulfur atom and a neutral sulfur atom. Over the past years, organothianthrenium salts have been emerging as ...attractive precursors for a myriad of transformations to forge new C-C and C-X bonds due to their unique structural characteristics and chemical behaviors. The use of the thianthrenation strategy selectively transforms C-H, C-O, and other chemical bonds into organothianthrenium salts in a predictable manner, providing a straightforward alternative for regioselective functionalizations for arenes, alkenes, alkanes, alcohols, amines and so on through diverse reaction mechanisms under mild conditions. In this review, the preparation of different organothianthrenium salts is summarized, including aryl, alkenyl and alkyl thianthrenium salts. Moreover, the utilization of organothianthrenium salts in different catalytic processes and their synthetic potentials are also discussed.
This review summarizes the synthesis of diverse organothianthrenium salts from various precursors and their applications in organic synthesis to forge new C-C, C-H and C-heteroatom bonds by C-S bond cleavage with different mechanistic considerations.
Chiral aliphatic amine and alcohol derivatives are ubiquitous in pharmaceuticals, pesticides, natural products and fine chemicals, yet difficult to access due to the challenge to differentiate ...between the spatially and electronically similar alkyl groups. Herein, we report a nickel-catalyzed enantioselective hydroalkylation of acyl enamines and enol esters with alkyl halides to afford enantioenriched α-branched aliphatic acyl amines and esters in good yields with excellent levels of enantioselectivity. The operationally simple protocol provides a straightforward access to chiral secondary alkyl-substituted amine and secondary alkyl-substituted alcohol derivatives from simple starting materials with great functional group tolerance.
The final assembly of terrestrial planets occurs via massive collisions, which can launch copious clouds of dust that are warmed by the star and glow in the infrared. We report the real-time ...detection of a debris-producing impact in the terrestrial planet zone around a 35-million-year-old solar-analog star. We observed a substantial brightening of the debris disk at a wavelength of 3 to 5 micrometers, followed by a decay over a year, with quasi-periodic modulations of the disk flux. The behavior is consistent with the occurrence of a violent impact that produced vapor out of which a thick cloud of silicate spherules condensed that were then ground into dust by collisions. These results demonstrate how the time domain can become a new dimension for the study of terrestrial planet formation.
Electronic skin sensing devices are an emerging technology and have substantial demand in vast practical fields including wearable sensing, robotics, and user‐interactive interfaces. In order to ...imitate or even outperform the capabilities of natural skin, the keen exploration of materials, device structures, and new functions is desired. However, the very high resistance and the inadequate current switching and sensitivity of reported electronic skins hinder to further develop and explore the promising uses of the emerging sensing devices. Here, a novel resistive cloth‐based skin‐like sensor device is reported that possesses unprecedented features including ultrahigh current‐switching behavior of ≈107 and giant high sensitivity of 1.04 × 104–6.57 × 106 kPa−1 in a low‐pressure region of <3 kPa. Notably, both superior features can be achieved by a very low working voltage of 0.1 V. Taking these remarkable traits, the device not only exhibits excellent sensing abilities to various mechanical forces, meeting various applications required for skin‐like sensors, but also demonstrates a unique competence to facile integration with other functional devices for various purposes with ultrasensitive capabilities. Therefore, the new methodologies presented here enable to greatly enlarge and advance the development of versatile electronic skin applications.
A newly designed cloth‐based resistive electronic skin features ultrahigh current switching of ≈107 and extremely high sensitivity of 1.04 × 104–6.57 × 106 kPa–1 at pressures <3 kPa. And, notably, both features are achieved by a very low working voltage of 0.1 V. Taking these traits, our devices not only function as ultrasensitive sensors but can also be integrated with various functional components for multipurpose uses.
While chemotherapy is the only approved non-surgical option for the majority of pancreatic cancer patients, it rarely results in a cure. The failure to respond to chemotherapy is due to the presence ...of an abundant dysplastic stroma that interferes in drug delivery and as a result of drug resistance. It is appropriate, therefore, to consider the stromal contribution to the resistance to chemotherapy and sidestepping this barrier with nanocarriers that improve survival outcome. In this paper, we provide a short overview of the role of the stroma in chemotherapy resistance, including the use of nanocarriers to negate this barrier. We provide a perspective and guidance towards the implementation of nanotherapeutic approaches to improve therapeutic delivery and efficacy of PDAC management.
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Aqueous aluminum batteries are promising post-lithium battery technologies for large-scale energy storage applications because of the raw materials abundance, low costs, safety and high theoretical ...capacity. However, their development is hindered by the unsatisfactory electrochemical behaviour of the Al metal electrode due to the presence of an oxide layer and hydrogen side reaction. To circumvent these issues, we report aluminum-copper alloy lamellar heterostructures as anode active materials. These alloys improve the Al-ion electrochemical reversibility (e.g., achieving dendrite-free Al deposition during stripping/plating cycles) by using periodic galvanic couplings of alternating anodic α-aluminum and cathodic intermetallic Al
Cu nanometric lamellas. In symmetric cell configuration with a low oxygen concentration (i.e., 0.13 mg L
) aqueous electrolyte solution, the lamella-nanostructured eutectic Al
Cu
alloy electrode allows Al stripping/plating for 2000 h with an overpotential lower than ±53 mV. When the Al
Cu
anode is tested in combination with an Al
MnO
cathode material, the aqueous full cell delivers specific energy of ~670 Wh kg
at 100 mA g
and an initial discharge capacity of ~400 mAh g
at 500 mA g
with a capacity retention of 83% after 400 cycles.
Bulk heterojunction (BHJ) photovoltaics represent one of the most promising technologies in low-cost, high-throughput, environmentally friendly energy conversion. Morphological control is one pillar ...of the recent remarkable progress in power conversion efficiency. This review focuses on morphological control by processing with solvent additives, which has been extensively adopted and exhibits promising compatibility with large-scale processing. Recent investigations including material selection, morphological variations at various length scales, and interpretations of the interaction among additives and BHJ materials will be discussed. Insights into the role of solvent additives represent an important resource for further improvement in materials and processing designs.
Although a growing number of innovations have emerged in the fields of nanobiotechnology and nanomedicine, new engineered nanomaterials (ENMs) with novel physicochemical properties are posing novel ...challenges to understand the full spectrum of interactions at the nano–bio interface. Because these could include potentially hazardous interactions, researchers need a comprehensive understanding of toxicological properties of nanomaterials and their safer design. In depth research is needed to understand how nanomaterial properties influence bioavailability, transport, fate, cellular uptake, and catalysis of injurious biological responses. Toxicity of ENMs differ with their size and surface properties, and those connections hold true across a spectrum of in vitro to in vivo nano–bio interfaces. In addition, the in vitro results provide a basis for modeling the biokinetics and in vivo behavior of ENMs. Nonetheless, we must use caution in interpreting in vitro toxicity results too literally because of dosimetry differences between in vitro and in vivo systems as well the increased complexity of an in vivo environment. In this Account, we describe the impact of ENM physicochemical properties on cellular bioprocessing based on the research performed in our groups. Organic, inorganic, and hybrid ENMs can be produced in various sizes, shapes and surface modifications and a range of tunable compositions that can be dynamically modified under different biological and environmental conditions. Accordingly, we cover how ENM chemical properties such as hydrophobicity and hydrophilicity, material composition, surface functionalization and charge, dispersal state, and adsorption of proteins on the surface determine ENM cellular uptake, intracellular biotransformation, and bioelimination versus bioaccumulation. We review how physical properties such as size, aspect ratio, and surface area of ENMs influence the interactions of these materials with biological systems, thereby affecting their hazard potential. We discuss our actual experimental findings and show how these properties can be tuned to control the uptake, biotransformation, fate, and hazard of ENMs. This Account provides specific information about ENM biological behavior and safety issues. This research also assists the development of safer nanotherapeutics and guides the design of new materials that can execute novel functions at the nano–bio interface.
Clock (circadian) genes are heterogeneously expressed in hair follicles (HFs). The genes can be modulated by both the central circadian system and some extrinsic factors, such as light and thyroid ...hormones. These circadian genes participate in the regulation of several physiological processes of HFs, including hair growth and pigmentation. On the other hand, because peripheral circadian genes are synchronized with the central clock, HFs could provide a noninvasive and practical method for monitoring and evaluating multiple circadian-rhythm-related conditions and disorders among humans, including day and night shifts, sleep-wake disorders, physical activities, energy metabolism, and aging. However, due to the complexity of circadian biology, understanding how intrinsic oscillation operates using peripheral tissues only may be insufficient. Combining HF sampling with multidimensional assays such as detection of body temperature, blood samples, or certain validated questionnaires may be helpful in improving HF applications. Thus, HFs can serve as a critical model for monitoring the circadian clock and can help provide an understanding of the potential mechanisms of circadian-rhythm-related conditions; furthermore, chronotherapy could support personalized treatment scheduling based on the gene expression profile expressed in HFs.
The production of engineered nanomaterials (ENMs) is a sci-entific breakthrough in material design and the development of new consumer products. While the successful implementation of nanotechnology ...is important for the growth of the global economy, we also need to consider the possible environmental health and safety (EHS) impact as a result of the novel physicochemical properties that could generate hazardous biological outcomes. In order to assess ENM hazard, reliable and reproducible screening approaches are needed to test the basic materials as well as nanoenabled products. A platform is required to investigate the potentially endless number of biophysicochemical interactions at the nano/bio interface, in response to which we have developed a predictive toxicological approach. We define a predictive toxicological approach as the use of mechanisms-based high-throughput screening in vitro to make predictions about the physicochemical properties of ENMs that may lead to the generation of pathology or disease outcomes in vivo. The in vivo results are used to validate and improve the in vitro high-throughput screening (HTS) and to establish structure–activity relationships (SARs) that allow hazard ranking and modeling by an appropriate combination of in vitro and in vivo testing. This notion is in agreement with the landmark 2007 report from the US National Academy of Sciences, “Toxicity Testing in the 21st Century: A Vision and a Strategy” (http://www.nap.edu/catalog.php?record_id=11970), which advocates increased efficiency of toxicity testing by transitioning from qualitative, descriptive animal testing to quantitative, mechanistic, and pathway-based toxicity testing in human cells or cell lines using high-throughput approaches. Accordingly, we have implemented HTS approaches to screen compositional and combinatorial ENM libraries to develop hazard ranking and structure–activity relationships that can be used for predicting in vivo injury outcomes. This predictive approach allows the bulk of the screening analysis and high-volume data generation to be carried out in vitro, following which limited, but critical, validation studies are carried out in animals or whole organisms. Risk reduction in the exposed human or environmental populations can then focus on limiting or avoiding exposures that trigger these toxicological responses as well as implementing safer design of potentially hazardous ENMs. In this Account, we review the tools required for establishing predictive toxicology paradigms to assess inhalation and environmental toxicological scenarios through the use of compositional and combinatorial ENM libraries, mechanism-based HTS assays, hazard ranking, and development of nano-SARs. We will discuss the major injury paradigms that have emerged based on specific ENM properties, as well as describing the safer design of ZnO nanoparticles based on characterization of dissolution chemistry as a major predictor of toxicity.
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