Eco-Friendly Water-Processable Polyimide Binders with High Adhesion to Silicon Anodes for Lithium-Ion Batteries

Silicon is an attractive anode material for lithium-ion batteries (LIBs) because of its natural abundance and excellent theoretical energy density. However, Si-based electrodes are difficult to commercialize because of their significant volume changes during lithiation that can result in mechanical damage. To overcome this limitation, we synthesized an eco-friendly water-soluble polyimide (W-PI) precursor, poly(amic acid) salt (W-PAmAS), as a binder for Si anodes via a simple one-step process using water as a solvent. Using the W-PAmAS binder, a composite Si electrode was achieved by low-temperature processing at 150 °C. The adhesion between the electrode components was further enhanced by introducing 3,5-diaminobenzoic acid, which contains free carboxylic acid (-COOH) groups in the W-PAmAS backbone. The -COOH of the W-PI binder chemically interacts with the surface of Si nanoparticles (SiNPs) by forming ester bonds, which efficiently bond the SiNPs, even during severe volume changes. The Si anode with W-PI binder showed improved electrochemical performance with a high capacity of 2061 mAh g^-1 and excellent cyclability of 1883 mAh g^-1 after 200 cycles at 1200 mA g^-1. Therefore, W-PI can be used as a highly effective polymeric binder in Si-based high-capacity LIBs.

Application of ZnO single-crystal wire grown by the thermal evaporation method as a chemical gas sensor for hydrogen sulfide

A zinc oxide single-crystal wire was synthesized for application as a gas-sensing material for hydrogen sulfide, and its gas-sensing properties were investigated in this study. The gas sensor consisted of a ZnO thin film as the buffer layer and a ZnO single-crystal wire. The ZnO thin film was deposited over a patterning silicon substrate with a gold electrode by the CFR method. The ZnO single-crystal wire was synthesized over the ZnO thin film using zinc and activated carbon as the precursor for the thermal evaporation method at 800 degrees C. The electrical properties of the gas sensors that were prepared for the growth of ZnO single-crystal wire varied with the amount of zinc contained in the precursor. The charged current on the gas sensors increased with the increasing amount of zinc in the precursor. It was concluded that the charged current on the gas sensors was related to ZnO single-crystal wire growth on the silicon substrate area between the two electrodes. The charged current on the gas sensor was enhanced when the ZnO single-crystal wire was exposed to a H2S stream. The experimental results obtained in this study confirmed that a ZnO single-crystal wire can be used as a gas sensor for H2S.

Effects of epidural injection on spinal block during combined spinal and epidural anesthesia for cesarean delivery

BACKGROUND AND OBJECTIVES

Epidural injection has been known to enhance spinal anesthesia in combined spinal and epidural (CSE) anesthesia. Saline and local anesthetics have been reported to have a volume effect, elevating sensory level when supplementing a volume into the epidural space. We evaluated the effects of epidural injection when using the CSE technique for cesarean delivery.

METHODS

Sixty-six parturients were allocated randomly into group C (control, n = 21), S (saline, n = 21), or B (bupivacaine, n = 24): epidural injections of 10 mL saline and 0.25% bupivacaine were given in groups S and B, respectively, 10 minutes after they received 8 mg of 0.5% hyperbaric bupivacaine intrathecally, and no injection was given in group C. The sensory level at 10 minutes, the maximal level and the time to reach it, and degree of motor block and muscle relaxation were compared. We also investigated intraoperative side effects and postoperative findings in the postanesthesia care unit.

RESULTS

Epidural injection raised the sensory level significantly in groups S and B, but the maximal height of sensory block and degree of muscle relaxation did not differ among the groups. Fewer patients complained of intraoperative pain in group B than in the other groups (P <.001).

CONCLUSIONS

We could not achieve satisfactory surgical analgesia with 8 mg of hyperbaric bupivacaine injected into the subarachnoid space using the needle-through-needle technique in cesarean deliveries. An epidural saline injection elevated the sensory level, which did not improve the spinal block, whereas an epidural injection of 10 mL of 0.25% bupivacaine enhanced the spinal block and sustained the block postoperatively.

2-fluoroabscisic acid analogues: their synthesis and biological activities

Fluorine was introduced into the 2-position of the side chain of abscisic acid (ABA) analogues by Wittig reaction of alpha-ionone derivatives with ethyl triethylphosphono-2-fluoroacetate. The effects of the fluorinated analogues were evaluated on inhibition of cress seed germination and inhibition of gibberellin-inducible alpha-amylase induction in embryoless barley half-seeds. (2E, 4E)-2-Fluoro-5-(1'-hydroxy-2',6', 6'-trimethyl-2'-cyclohexen-1'-yl)-3-methyl-2,4-pentadienoic acid (5b) showed potent inhibitory activity at the same level as ABA in the cress seed germination test, and 5b also inhibited gibberellin-inducible alpha-amylase induction at 4 x 10(-)(6), 3 times the concentration of ABA (1 x 10(-)(6)) for 50% inhibition of alpha-amylase production. 5b also showed dehydrin induction activity. These results indicate that fluorinated ABA analogues mimic ABA action and can be a lead for a plant growth regulator which regulates plant growth or protects plants from environmental stresses.