Bis(η5-cyclopentadienyl)(2-{[(2-methoxyphenyl)imino]methyl}phenolato-κ3 O,N,O′)terbium

The air- and moisture-sensitive title compound, [Tb(C5H5)2(C14H12NO2)], was synthesized from tris(cyclopentadienyl)(tetrahydrofuran)terbium and 2-{[(2-methoxyphenyl)imino]methyl}phenol. Each Tb atom is coordinated by two cyclopentadienyl ligands in an η5-coordination mode and by one N and two O atoms of the organic ligand in a tridentate κ3 O,N,O′-mode.

Characterization and evaluation of novel sustainable polymers derived from renewable rosin

Purpose This study aims to prepare low-cost biomaterials from renewable natural resources (rosin). Design/methodology/approach Preparation of different biomaterials, ethylene glycol maleic rosin (EGMR), glycerol maleic rosin, pentaerythritol maleic rosin and sorbitol maleic rosin (SMR) esters, then evaluated by stability studies, moisture absorption, swelling index parameters, thermogravimetric analysis and skin irritation studies. Findings The prepared rosin derivatives had excellent moisture safety, according to the results. From EGMR to SMR, the swelling indices increase. Research limitations/implications These rosin biomaterials were used in coating, especially in the field of pharmaceutical coating, and good results were obtained in this study. Practical implications As these biomaterials rosin derivatives have excellent moisture resistance, they are recommended for use as coating materials for moisture-sensitive drugs. Originality/value There has recently been a lot of interest in researching the effects of rosin derivatives in various drug delivery systems.

Compositional Features and Swelling Potential of Two Weak Rock Types Affecting Their Slake Durability

Weak and weathered rocks are well known for their sensitivity to changes in moisture content. Degrading behavior is common in weak rocks with moisture-sensitive mineral components and present numerous stability problems. The slake durability is a measure of the resistance to weakening and disintegration of rock materials which quantitatively distinguishes durable from non-durable rock materials. Several rock material parameters interact on the process of disintegration when exposed to cyclic moisture changes, whereby the content of clay is believed to play a major role. This manuscript evaluates the overall material composition of flysch and serpentinite rocks cored from the wall of the shotcrete-lined headrace tunnel of a hydropower project, including minerals, structure, porosity, the presence of micro-discontinuities, and swelling potential, and links these properties to the slake durability. Further, the different methods used to assess compositional features affecting the durability of weak rocks are evaluated and discussed. The manuscript argues that the mineralogical composition and microstructures present in the intact rock and the content of moisture-sensitive constituents, as swelling clays, control the long-term durability of weak rock material. It is demonstrated that XRD assessments are not sufficient to detect the content of brucite and swelling components, and that methods as thin section and SEM analyses should be carried out in the assessment of weak and weathered rock mass.

MATHEMATICAL SIMULATION OF A DEVICE WITH FREQUENCY OUTPUT FOR MEASUREMENT OF HUMIDITY

The device for measuring humidity with a moisture-sensitive resistive element HR202 has been developed. The self-generating transducer is designed as a hybrid integrated circuit based on a bipolar transistor VT1 and a field-effect two-gate transistor VT2. The negative differential resistance, which is formed by the parallel connection of the impedance with a capacitive component at the collector electrodes of the bipolar transistor VT1, the drain of the field-effect transistor VT2 and inductance L1, leads to the occurrence of electrical oscillations in the circuit. When exposed to moisture on the sensitive resistive element RW, the capacitive component of the impedance at the electrodes of the transistor structure changes, which causes an effective change in the frequency of the oscillatory circuit. On the basis of mathematical modeling of electrical characteristics, analytical expressions for the transformation function and the sensitivity equation are obtained. It has been experimentally established that an increase in the ambient temperature in the range of relative humidity W = 30 ÷ 85% leads to an expansion of the generation range of the autogenerating humidity transducer, as well as to an increase in the sensitivity of the device to the measured value. The generation range of the autogenerating humidity transducer at a temperature of T = 20 °C acquires a value of 823 kHz (the average value of the sensitivity is 16.18 kHz /%), and at a temperature of T = 50 °C – 1323 kHz (the average value of the sensitivity is 29.10 kHz / %). To confirm the theoretical results of circuit solutions developed device in the computer modeling of LTSpice modeling environment. The studies were carried out at different temperatures (20°C, 30°C, 40°C, 50°C) in the range of change in the resistance of the moisture-sensitive resistive element from 1750 kOhm to 2.1 kOhm, which corresponds to an increase in the value of the relative air humidity from 30 % to 90 %. The results of theoretical and experimental studies have shown that at the output there are periodic oscillations device for measuring the humidity rate which increases with increasing values ​​of relative humidity. The obtained theoretical and experimental studies are in good agreement, the relative error does not exceed 2.5%.

Conductive Polymer (Graphene/PPy)–BiPO4 Composite Applications in Humidity Sensors

In this particular experiment, a chain of conductive polymer graphene/polypyrrole (Gr/PPy) and BiPO4—or (Gr/PPy)–BiPO4—materials were prepared and used as moisture-sensitive materials. The structure and morphology of the conductive polymer (Gr/PPy)–BiPO4 materials were analyzed using an X-ray diffractometer, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Moreover, properties such as hysteresis loop, impedance, sensing response, and response and recovery time were calculated and evaluated using an inductance–capacitance–resistance analyzer. The data expressed that PPy/BiPO4, as prepared in this study, exhibited excellent sensing properties, with impedance changing by only a few orders of range. Furthermore, the response time and time of recovery were 340 s and 60 s, respectively, and negligible humidity hysteresis occurred at different relative humidities. Therefore, conductive PPy/BiPO4, as prepared in the present study, is an excellent candidate for application in humidity sensors.

A Ball Milling Enabled Cross-Electrophile Coupling

<div><div><div><p>The nickel-catalyzed cross-electrophile coupling of aryl (pseudo)halides and alkyl (pseudo)halides enabled by ball-milling is herein described. Under a mechanochemical manifold, the reductive C–C bond formation was achieved in the absence of bulk solvent and air/moisture sensitive set-ups, in reaction times of 2 hours. The mechanical action provided by ball milling permits the use of a range of zinc sources to turnover the catalytic cycle of nickel. A library of 28 cross- electrophile coupled building blocks has been constructed to exemplify this technique.</p></div></div></div>

A Ball Milling Enabled Cross-Electrophile Coupling

<div><div><div><p>The nickel-catalyzed cross-electrophile coupling of aryl (pseudo)halides and alkyl (pseudo)halides enabled by ball-milling is herein described. Under a mechanochemical manifold, the reductive C–C bond formation was achieved in the absence of bulk solvent and air/moisture sensitive set-ups, in reaction times of 2 hours. The mechanical action provided by ball milling permits the use of a range of zinc sources to turnover the catalytic cycle of nickel. A library of 28 cross- electrophile coupled building blocks has been constructed to exemplify this technique.</p></div></div></div>

Enantioselective a,d-Difunctionalization of Dienes Initiated by Rh-Catalyzed Conjugate Addition

Metal-catalyzed enantioselective conjugate additions are highly reliable methods for stereoselective synthesis, however multi-component reactions that are initiated by conjugate arylation of acyclic p-systems are rare. These processes generally proceed with poor diastereoselectivity while requiring basic, moisture sensitive organometallic nucleophiles. Here we show that Rh-catalysts supported by a tetrafluorobenzobarrelene ligand (Ph-tfb) enable the enantio-, diastereo-, and Z-selective a,d-difunctionalization of electron-deficient 1,3-dienes with organoboronic acid nucleophiles and aldehyde electrophiles to generate Z-homoallylic alcohols with three stereocenters. The reaction accommodates diene substrates activated by ester, amide, ketone, or aromatic groups and can be used to couple aryl, alkenyl, or alkyl aldehydes. Diastereoselective functionalization of the Z-olefin unit in the addition products allow for the generation of compounds with five stereocenters in high dr and ee. Mechanistic studies suggest aldehyde allylrhodation is the rate determining step, and unlike reactions of analogous Rh-enolates, the Rh-allyl species generated by d-arylation undergoes aldehyde trapping rather than protonolysis, even when water is present as a co-solvent. These findings should have broader implications in the use of privileged metal-catalyzed conjugate addition reactions as entry points towards the preparation of acyclic molecules containing non-adjacent stereocenters.