ABSTRACT
Gas-liquid (G-L) reactive crystallization is a major technology for advanced materials construction, which requires a short diffusion path on the interface to ensure the reactant supply and stable crystal nucleation under ultrahigh supersaturation. Herein, a covalent organic framework (COF) membrane with homo hierarchical pore structures was proposed as an effective interfacial material for the regulation of confined reactive crystallization. By combining the ordered nanopores of COFs and micropores of anodic aluminum oxide (AAO), the COF membrane simultaneously provided an excellent nanoscale diffusion-reaction regulation network as the molecular-level confined G-L reactive interface and adjustable submicrometer gas mass transfer channels. The highly selective construction of CaCO3 superstructures was then achieved. When the submicrometer primary pore size rp of the constructed COF membrane ranged from 120 to 1.6 nm, the diffusion mechanism of CO2 varied from viscous flow diffusion to Knudsen diffusion. The growth orientation of CaCO3 crystals was well confined to obtain spindle-shaped crystals with high selectivity. Meanwhile, the crystal selectivity factor (cube/sphere) increased from 0 to 3.53 under the low interfacial nuclear barrier. Thus, the COF membrane with coupled micro-nanostructures successfully screened the directional preparation conditions for diverse CaCO3 superstructures, which also paved a meaningful path for the functional application of COFs in accurate mass transfer control and confined chemical reactions.
ABSTRACT
The number of patients with cardiovascular diseases is rapidly increasing in the world. The workload of existing clinicians is consequently increasing. However, the number of cardiovascular clinicians is declining. In this paper, we aim to design a mobile and automatic system to improve the abilities of patients' cardiovascular health management while also reducing clinicians' workload. Our system includes both hardware and cloud software devices based on recent advances in Internet of Things (IoT) and Artificial Intelligence (AI) technologies. A small hardware device was designed to collect high-quality Electrocardiogram (ECG) data from the human body. A novel deep-learning-based cloud service was developed and deployed to achieve automatic and accurate cardiovascular disease detection. Twenty types of diagnostic items including sinus rhythm, tachyarrhythmia, and bradyarrhythmia are supported. Experimental results show the effectiveness of our system. Our hardware device can guarantee high-quality ECG data by removing high-/low-frequency distortion and reverse lead detection with 0.9011 Area Under the Receiver Operating Characteristic Curve (ROC-AUC) score. Our deep-learning-based cloud service supports 20 types of diagnostic items, 17 of them have more than 0.98 ROC-AUC score. For a real world application, the system has been used by around 20,000 users in twenty provinces throughout China. As a consequence, using this service, we could achieve both active and passive health management through a lightweight mobile application on the WeChat Mini Program platform. We believe that it can have a broader impact on cardiovascular health management in the world.
Subject(s)
Artificial Intelligence , Cardiovascular Diseases , Cloud Computing , China , Humans , Intelligence , ROC CurveABSTRACT
4-( p-Methoxyphenyl)-4-pentenylthioglycosides (MPTGs) undergo acid-catalyzed O-glycosylation with a range of alcohol acceptors in the presence of 10 mol % of triflic acid at room temperature. Particularly encouraging is the reactivity of MPTGs toward unreactive acceptors. MPTGs can be synthesized from the requisite vinyl bromides using the Suzuki reaction, and this chemistry can be leveraged toward a "latent-active" strategy for oligosaccharide synthesis.
ABSTRACT
Two classes of thioglycoside, 4-(4-methoxyphenyl)-3-butenylthioglycosides (MBTGs) and 4-(4-methoxyphenyl)-4-pentenylthioglycosides (MPTGs), undergo acid-catalyzed O-glycosylations with a range of sugar and nonsugar alcohols at 25 °C. Electron density at the styrene alkene is critical for reactivity while sugar protecting group patterns have a minimal effect. In contrast with most methods for thioglycoside activation, acid-catalyzed activation of MBTGs is compatible with electroneutral alkenes.
ABSTRACT
Visible-light irradiation of ortho-diazoniaphenyl alkyl sulfones in the presence of Ru(bpy)32+ results in remote Csp3-H functionalization. Key mechanistic steps in these processes involve intramolecular hydrogen atom transfer from Csp3-H bonds to aryl radicals to generate alkyl/benzyl radicals. Subsequent polar crossover occurs by single-electron oxidation of the alkyl/benzyl radicals to carbenium ions that then intercept nucleophiles. We have developed remote hydroxylations, etherifications, an amidation, and C-C bond formation processes using this strategy.
ABSTRACT
We report an operationally simple, visible-light-driven protocol for intramolecular C-H difluoroacetamidation of arenes for the synthesis of biologically relevant 3,3-difluoro-2-oxindoles at room temperature. Using fac-Ir(ppy)3 as a photocatalyst and a 3 W blue LED as a light source, an array of difluoroxindoles was prepared from rapidly available tertiary aryl bromodifluoroacetamides in moderate to excellent yields.
ABSTRACT
When and how often to release information on television are important issues in crisis and emergency risk communication. There is a lot of crisis information, including warnings and news, to which people should have access, but most of it is not significantly urgent to interrupt the broadcasting of television programmes. Hence, the right timing for the release of crisis information should be selected based on the importance of the crisis and any associated communication requirements. Using recursive methods, this paper builds an audience coverage model of crisis information release. Based on 2007 Household Using TV (HUT) data for Hefei City, China, the optimal combination of broadcasting sequence (with frequencies between one and eight times) is obtained using the implicit enumeration method. The developed model is applicable to effective transmission of crisis information, with the aim of reducing interference with the normal television transmission process and decreasing the psychological effect on audiences. The same model can be employed for other purposes, such as news coverage and weather and road information.
