Imidazol-1-yl-acetic acid as a novel green bifunctional organocatalyst for the synthesis of 1, 8-dioxooctahydroxanthenes under solvent-free conditions

Imidazol-1-yl-acetic acid is introduced as a new, efficient and recyclable green bifunctional organocatalyst for the synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions. This catalyst is water soluble and can be separated from the products by simple filtration. The filtrate can be evaporated to dryness and recrystallized from cool methanol to give the recovered catalyst. This organocatalyst was used for the synthesis of 1,8-dioxooctahydroxanthenes under solvent-flee conditions and recycled up to 8 consecutive runs without any losing of its efficiency.     

Paper‐Based Electrical Respiration Sensor

Current methods of monitoring breathing require cumbersome, inconvenient, and often expensive devices; this requirement sets practical limitations on the frequency and duration of measurements. This article describes a paper‐based moisture sensor that uses the hygroscopic character of paper (i.e. the ability of paper to adsorb water reversibly from the surrounding environment) to measure patterns and rate of respiration by converting the changes in humidity caused by cycles of inhalation and exhalation to electrical signals. The changing level of humidity that occurs in a cycle causes a corresponding change in the ionic conductivity of the sensor, which can be measured electrically. By combining the paper sensor with conventional electronics, data concerning respiration can be transmitted to a nearby smartphone or tablet computer for post‐processing, and subsequently to a cloud server. This means of sensing provides a new, practical method of recording and analyzing patterns of breathing.     

活性炭负载硫化锡纳米颗粒作为高效可重复使用Lewis酸催化剂催化三组分一锅法合成4H-吡喃[2,3-c]吡唑衍生物(英文)

Tin sulfide nanoparticles(SnS -NPs) were prepared in aqueous solution at room temperature on the surface of activated carbon(AC) and were investigated using field-emission scanning electron mi-croscopy(FE-SEM), transmission electron microscopy(TEM), X-ray diffraction, reflective ultravio-let-visible spectrophotometry, and spectrofluorimetry. Calculations based on the SEM and TEM images showed that the sizes of the SnS -NPs immobilized on the AC were 30–70 nm. The prepared nanocomposite was used as a heterogeneous Lewis acid catalyst for the three-components one-pot synthesis of 4H-pyrano[2,3-c]pyrazole derivatives in ethanol at 80 ℃. The reactions were efficiently performed in the presence of the prepared catalyst in short reaction times, and gave the desired products in high yields. This catalyst can be easily recovered by simple filtration and recycled up to eight consecutive times without significant loss of its efficiency.     

Next-generation integrated microfluidic circuits

This mini-review provides a brief overview of recent devices that use networks of elastomeric valves to minimize or eliminate the need for interconnections between microfluidic chips and external instruction lines that send flow control signals. Conventional microfluidic control mechanisms convey instruction signals in a parallel manner such that the number of instruction lines must increase as the number of independently operated valves increases. The devices described here circumvent this "tyranny of microfluidic interconnects" by the serial encoding of information to enable instruction of an arbitrary number of independent valves with a set number of control lines, or by the microfluidic circuit-embedded encoding of instructions to eliminate control lines altogether. Because the parallel instruction chips are the most historical and straightforward to design, they are still the most commonly used approach today. As requirements for instruction complexity, chip-to-chip communication, and real-time on-chip feedback flow control arise, the next generation of integrated microfluidic circuits will need to incorporate these latest interconnect flow control approaches.     

Copper iodide nanoparticles on poly(4-vinyl pyridine) as new and green catalyst for multicomponent click synthesis of 1,4-disubstituted-l,2,3-triazoles in water

Poly(4-vinyl pyridine) supported nanoparticle of copper(Ⅰ) iodide is reported as a green and recyclable catalyst for the regioselective synthesis of 1,4-disubstituted-1H-1,2,3-triazoles from benzyl halides,sodium azide and terminal alkynes in water. This catalyst can be recovered by simple filtration and recycled up to 8 consecutive runs without any loss of its efficiency.     

High-density fabrication of normally closed microfluidic valves by patterned deactivation of oxidized polydimethylsiloxane

The use of polydimethylsiloxane (PDMS) in microfluidic devices is extensive in academic research. One of the most fundamental treatments is to expose PDMS to plasma oxidation in order to render its surface temporarily hydrophilic and capable of permanent bonding. Here, we show that changes in the surface chemistry induced by plasma oxidation can spatially be counteracted very cleanly and reliably in a scalable manner by subsequent microcontact printing of residual oligomers from a PDMS stamp. We characterize the surface modifications through contact angle, atomic force microscopy, X-ray photoelectron spectroscopy, and bond-strength measurements. We utilize this approach for negating the bonding of a flexible membrane layer within an elastomeric valve and demonstrate its effectiveness by integration of over one thousand normally closed elastomeric valves within a single substrate. In addition, we demonstrate that surface energy patterning can be used for "open microfluidic" applications that utilize spatial control of surface wetting.     

Introduction of novel brønsted acidic ionic liquids with perchlorate counter-anion for one-pot synthesis of symmetric 3,3′-diaryloxindoles

Research on Chemical Intermediates - In this work, three novel 1,4-butane sultone-based Brønsted acidic ionic liquids with Perchlorate conter-anion are prepared. These newly introduced ionic...     

Ion-pair immobilization of l-prolinate anion onto cationic polymer support and a study of its catalytic activity as an efficient heterogeneous catalyst for the synthesis of 2-amino-4H-chromene derivatives

Research on Chemical Intermediates - A novel clean and simple technique for the heterogenization of l-proline organocatalyst has been introduced. This procedure is based on non-covalent...