A Computer Simulation Study on Self- and Cross-Aggregation of Multiple Polar Species in Supercritical Carbon Dioxide

The effect of hydrogen-bond cooperativity on self- and cross-aggregation of multiple polar species in supercritical carbon dioxide was investigated using both ab initio calculations and Monte Carlo simulations. Ab initio calculations indicate that hydrogen-bond cooperativity has a significant impact on the cluster size, but does not greatly influence the composition of clusters. The microscopic structures in the ethanol + CO2 and acetic acid + CO2 binary mixtures were first studied using Monte Carlo simulations with a strict set of criteria for hydrogen bonding, and a satisfactory agreement with experimental data was achieved. The state of microscopic phase separation in the ethanol + water + CO2 and acetic acid + water + CO2 ternary mixtures was then extensively investigated, indicating that the size and composition of aggregates are strongly dependent on the mixing ratio. Moreover, hydrogen-bond cooperativity must be considered to acquire more thorough understanding of the hydration process. On the basis of the detailed distributions of aggregate size and structure, a new two-staged hydration mechanism was finally proposed for the ternary solutions

Computer Simulations on Aggregation of Acetic Acid in the Gas Phase, Liquid Phase, and Supercritical Carbon Dioxide

Computer simulations including semiempirical molecular orbital and Monte Carlo methods were employed to investigate the aggregation of acetic acid in the gas phase, liquid phase, and supercritical carbon dioxide. The binary vapor−liquid coexistence curves of the CO2/acetic acid mixtures were calculated at 313.2, 333.2, and 353.2 K and are in excellent agreement with experimental measurements. Two sets of rigorous hydrogen-bonding criteria were established for the hydrogen bonding at the hydroxyl oxygen and carbonyl oxygen, respectively. With the criteria, detailed statistics of hydrogen bonding states and distribution of aggregate sizes and structures were fully investigated and compared in the three phases, which will shed light on the development of more rigorous and accurate real associated solution models in the future

One-Pot, Water-Based Disruption of Cell Walls and Astaxanthin Extraction from Haematococcus pluvialis by Mechanochemistry

In this study, a new method for efficient astaxanthin extraction from Haematococcus pluvialis (H. pluvialis) by mechanochemistry was developed. The method is a water-based and water-reused one-pot procedure, which can simultaneously achieve cell wall breaking and astaxanthin extraction from H. pluvialis. In addition, the optimized process parameters were determined based on studies of different conditions; an elevated recovery of astaxanthin extraction yield (91.6 wt %) was achieved using 1 g of dried H. pluvialis and 4 mL of water at 200 rpm in 30 min with a ball-to-material ratio of 90 (m/m). The underlying mechanism revealed the extraction process by electron microscopy, thermodynamic analysis, spectroscopic determination, and particle size distribution analysis. The results of this study followed the sustainability criteria that include the concept of circular economy and contribute to the achievement of items 3, 6, 12, and 14 of the UN Sustainable Development Goals.1 This method innovates a new way for green and gentle extraction of natural fatty-soluble substances

Reversibly Sticking Metals and Graphite to Hydrogels and Tissues

We have discovered that hard, electrical conductors (e.g., metals or graphite) can be adhered to soft, aqueous materials (e.g., hydrogels, fruit, or animal tissue) without the use of an adhesive. The adhesion is induced by a low DC electric field. As an example, when 5 V DC is applied to graphite slabs spanning a tall cylindrical gel of acrylamide (AAm), a strong adhesion develops between the anode (+) and the gel in about 3 min. This adhesion endures after the field is removed, and we term it as hard–soft electroadhesion or EA[HS]. Depending on the material, adhesion occurs at the anode (+), cathode (−), or both electrodes. In many cases, EA[HS] can be reversed by reapplying the field with reversed polarity. Adhesion via EA[HS] to AAm gels follows the electrochemical series: e.g., it occurs with copper, lead, and tin but not nickel, iron, or zinc. We show that EA[HS] arises via electrochemical reactions that generate chemical bonds between the electrode and the polymers in the gel. EA[HS] can create new hybrid materials, thus enabling applications in robotics, energy storage, and biomedical implants. Interestingly, EA[HS] can even be achieved underwater, where typical adhesives cannot be used

Reversibly Sticking Metals and Graphite to Hydrogels and Tissues

We have discovered that hard, electrical conductors (e.g., metals or graphite) can be adhered to soft, aqueous materials (e.g., hydrogels, fruit, or animal tissue) without the use of an adhesive. The adhesion is induced by a low DC electric field. As an example, when 5 V DC is applied to graphite slabs spanning a tall cylindrical gel of acrylamide (AAm), a strong adhesion develops between the anode (+) and the gel in about 3 min. This adhesion endures after the field is removed, and we term it as hard–soft electroadhesion or EA[HS]. Depending on the material, adhesion occurs at the anode (+), cathode (−), or both electrodes. In many cases, EA[HS] can be reversed by reapplying the field with reversed polarity. Adhesion via EA[HS] to AAm gels follows the electrochemical series: e.g., it occurs with copper, lead, and tin but not nickel, iron, or zinc. We show that EA[HS] arises via electrochemical reactions that generate chemical bonds between the electrode and the polymers in the gel. EA[HS] can create new hybrid materials, thus enabling applications in robotics, energy storage, and biomedical implants. Interestingly, EA[HS] can even be achieved underwater, where typical adhesives cannot be used

Reversibly Sticking Metals and Graphite to Hydrogels and Tissues

We have discovered that hard, electrical conductors (e.g., metals or graphite) can be adhered to soft, aqueous materials (e.g., hydrogels, fruit, or animal tissue) without the use of an adhesive. The adhesion is induced by a low DC electric field. As an example, when 5 V DC is applied to graphite slabs spanning a tall cylindrical gel of acrylamide (AAm), a strong adhesion develops between the anode (+) and the gel in about 3 min. This adhesion endures after the field is removed, and we term it as hard–soft electroadhesion or EA[HS]. Depending on the material, adhesion occurs at the anode (+), cathode (−), or both electrodes. In many cases, EA[HS] can be reversed by reapplying the field with reversed polarity. Adhesion via EA[HS] to AAm gels follows the electrochemical series: e.g., it occurs with copper, lead, and tin but not nickel, iron, or zinc. We show that EA[HS] arises via electrochemical reactions that generate chemical bonds between the electrode and the polymers in the gel. EA[HS] can create new hybrid materials, thus enabling applications in robotics, energy storage, and biomedical implants. Interestingly, EA[HS] can even be achieved underwater, where typical adhesives cannot be used

Melatonin promotes apoptosis of thyroid cancer cells via regulating the signaling of microRNA-21 (miR-21) and microRNA-30e (miR-30e)

Melatonin (MEL) is an effective therapeutic choice for thyroid cancer treatment. In this study, we aimed to explored the potential effect of MEL upon the drug sensitivity of cancer cells and the according underlying mechanisms. Thyroid cancer mice were established as a control group and a MEL group to observe the in vivo effect of MEL. Tumor size and weight in nude mice were detected to evaluate the effect of MEL on tumor growth. Immunohistochemistry assay (IHC) and Western blot were performed to analyze the expression of PTEN protein in tumor cells or tumor cells. After 32 days of cancer cell implantation, MEL was found to significantly repress tumor growth in nude mice approximately by half. Moreover, MEL also suppressed tumor cell proliferation, while apparently activating the apoptosis of tumor cells. In addition, hydrogen sulfide (H2S) production was obviously elevated by MEL treatment. Mechanistically, the expression of phosphatase and tensin homolog (PTEN) was remarkably activated by MEL treatment in tumor tissues of implanted TPC-1 and BCPaP cells in nude mice. Meanwhile, MEL inhibited the expression of miR-21 and miR-30e and promoted the expression of lncRNA-cancer susceptibility candidate 7 (CASC7). Both miR-21 and miR-30e could suppress PTEN expression, while miR-21 could also inhibit the expression of lncRNA-CASC7. In conclusion, the results demonstrated that the MEL administration could downregulate the expression of miR-21 and miR-30e, which resulted in increased expression of PTEN, a pro-apoptotic tumor suppressor, to promote the apoptosis of thyroid cancer cells.</p

Reversibly Sticking Metals and Graphite to Hydrogels and Tissues

We have discovered that hard, electrical conductors (e.g., metals or graphite) can be adhered to soft, aqueous materials (e.g., hydrogels, fruit, or animal tissue) without the use of an adhesive. The adhesion is induced by a low DC electric field. As an example, when 5 V DC is applied to graphite slabs spanning a tall cylindrical gel of acrylamide (AAm), a strong adhesion develops between the anode (+) and the gel in about 3 min. This adhesion endures after the field is removed, and we term it as hard–soft electroadhesion or EA[HS]. Depending on the material, adhesion occurs at the anode (+), cathode (−), or both electrodes. In many cases, EA[HS] can be reversed by reapplying the field with reversed polarity. Adhesion via EA[HS] to AAm gels follows the electrochemical series: e.g., it occurs with copper, lead, and tin but not nickel, iron, or zinc. We show that EA[HS] arises via electrochemical reactions that generate chemical bonds between the electrode and the polymers in the gel. EA[HS] can create new hybrid materials, thus enabling applications in robotics, energy storage, and biomedical implants. Interestingly, EA[HS] can even be achieved underwater, where typical adhesives cannot be used

Enantioselective C(sp³)–C(sp³) Reductive Cross-Electrophile Coupling of Unactivated Alkyl Halides with α‑Chloroboronates via Dual Nickel/Photoredox Catalysis

Substantial advances in enantioconvergent C­(sp3)–C­(sp3) bond formations have been made with nickel-catalyzed cross-coupling of racemic alkyl electrophiles with organometallic reagents or nickel-hydride-catalyzed hydrocarbonation of alkenes. Herein, we report an unprecedented enantioselective C­(sp3)–C­(sp3) reductive cross-coupling by the direct utilization of two different alkyl halides with dual nickel/photoredox catalysis system. This highly selective coupling of racemic α-chloroboronates and unactivated alkyl iodides furnishes chiral secondary alkyl boronic esters, which serve as useful and important intermediates in the realm of organic synthesis and enable a desirable protocol to fast construction of enantioenriched complex molecules

Deoxygenative Arylboration of Aldehydes via Copper and Nickel/Photoredox Catalysis

Deoxygenative difunctionalization of carbonyls represents a convenient route to construct complex molecules considering the readily available aldehyde and ketone compounds. The present approaches typically rely on strategies via carbene, carbanion, or carbocation equivalents. Herein, combined with dual nickel/photoredox catalysis regime, we developed a strategy through a radical intermediate to achieve the deoxygenative arylboration of aldehydes. Compared with the known patterns of carbon–oxygen (C–O) bond transformations, this coupling of C-OBPin unit opens a direction for this chemistry. A wide variety of substrates bearing a diverse set of functional groups were compatible with this method under very mild conditions (visible light, ambient temperature, no strong base) to afford the benzylic boronic esters, which have important versatilities in organic synthesis