Reversible Switching Between Microwave Absorption and EMI Shielding of VO2 Composite Foam.

Developing lightweight composite with reversible switching between microwave (MW) absorption and electromagnetic interference (EMI) shielding is promising yet remains highly challenging due to the completely inconsistent attenuation mechanism for electromagnetic (EM) radiation. Here, a lightweight vanadium dioxide/expanded polymer microsphere composites foam (VO2/EPM) is designed and fabricated with porous structures and 3D VO2 interconnection, which possesses reversible switching function between MW absorption and EMI shielding under thermal stimulation. The VO2/EPM exhibits MW absorption with a broad effective absorption bandwidth of 3.25 GHz at room temperature (25 °C), while provides EMI shielding of 23.1 dB at moderately high temperature (100 °C). This reversible switching performance relies on the porous structure and tunability of electrical conductivity, complex permittivity, and impedance matching, which are substantially induced by the convertible crystal structure and electronic structure of VO2. Finite element simulation is employed to qualitatively investigate the change in interaction between EM waves and VO2/EPM before and after the phase transition. Moreover, the application of VO2/EPM is demonstrated with a reversible switching function in controlling wireless transmission on/off, showcasing its excellent cycling stability. This kind of smart material with a reversible switching function shows great potential in next-generation electronic devices.

Low LH level does not indicate poor IVF cycle outcomes with GnRh-a single trigger: a retrospective analysis.

OBJECTIVE: To compare the in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycle outcomes between patients with low and normal serum luteinizing hormone (LH) levels on the day after a gonadotropin-releasing hormone agonist (GnRH-a) single trigger. We further investigated the efficacy of human chorionic gonadotropin (hCG) retrigger on IVF cycle outcomes in patients with low LH levels after GnRH-a single trigger. METHODS: We retrospectively analyzed 957 infertile patients (tubal factor, ovulation disorders, male sperm factor, or unexplained infertility) who were treated with IVF/ICSI at the Chengdu Xinan Gynecology Hospital from July 2017 to December 2020. Patients received sufficient GnRH-a single trigger were divided into two groups based on the serum LH levels on the next day of trigger: normal serum LH levels (≥ 10 mIU/mL) group (control group, n = 906) and low LH levels (< 10 mIU/mL) group (experimental group, n = 51). And the efficacy of hCG retrigger on IVF/ICSI cycle outcomes in 10 patients with low LH levels after GnRH-a single trigger. RESULTS: There were no significant differences in IVF/ICSI cycle outcomes, including egg yield, two pronuclei fertilization rate, excellent embryo rate, or live birth rate of frozen-thawed embryos between patients with low and normal LH levels after GnRH-a trigger. It showed significantly higher risk of ovarian hyperstimulation syndrome in the group of low LH levels [ 0.7%(1/137) vs. 8.5%(4/47), P = 0.016] compared with the group of normal LH levels who received GnRH-a single trigger. The hCG retrigger had no obvious efficacy on cycle outcomes in patients with low LH levels, including oocytes retrieved, fertilization rate, embryo conditions, and live birth rate of frozen-thawed cycles. CONCLUSION: The IVF/ICSI cycle outcomes of patients with low LH levels on the day after GnRH-a administration were similar to those of patients with normal LH levels. Blood LH test might not be required on the day following the trigger. The hCG retrigger did not have any effect on the cycle outcomes, suggesting that immediate retriggering with hCG was unnecessary.

Determination of strychnine, brucine, strychnine N-oxide, and brucine N-oxide in plasma samples after the oral administration of processed semen strychni extract by high-performance liquid chromatography with ultrasound-assisted mixed cloud point extraction.

A sensitive and efficient mixed cloud point extraction combined with high-performance liquid chromatography was developed for the simultaneous separation and determination of four alkaloids (strychnine, strychnine N-oxide, brucine, and brucine N-oxide) in plasma after the oral administration of processed semen strychni extract. Tergitol TMN-6 and cetyl-trimethyl ammonium bromide were chosen as the mixed surfactants, and ultrasound was employed to enhance the extraction efficiency. Some important parameters affecting the mixed cloud point extraction efficiency, such as the content of Tergitol TMN-6 and cetyl-trimethyl ammonium bromide, pH, salt effect, extraction temperature, and ultrasound time were studied and optimized. Under optimum conditions, the linear range of four alkaloids was from 1.0 to 1000 ng/mL. All correlation coefficients of the calibration curves were higher than 0.9993. The intraday and interday precision were below 8.65% and the limits of detection for the four alkaloids were less than 1.0 ng/mL (S/N = 3).

Enhancing the Interaction of Carbon Nanotubes by Metal-Organic Decomposition with Improved Mechanical Strength and Ultra-Broadband EMI Shielding Performance.

The remarkable properties of carbon nanotubes (CNTs) have led to promising applications in the field of electromagnetic interference (EMI) shielding. However, for macroscopic CNT assemblies, such as CNT film, achieving high electrical and mechanical properties remains challenging, which heavily depends on the tube-tube interactions of CNTs. Herein, we develop a novel strategy based on metal-organic decomposition (MOD) to fabricate a flexible silver-carbon nanotube (Ag-CNT) film. The Ag particles are introduced in situ into the CNT film through annealing of MOD, leading to enhanced tube-tube interactions. As a result, the electrical conductivity of Ag-CNT film is up to 6.82 × 105 S m-1, and the EMI shielding effectiveness of Ag-CNT film with a thickness of ~ 7.8 µm exceeds 66 dB in the ultra-broad frequency range (3-40 GHz). The tensile strength and Young's modulus of Ag-CNT film increase from 30.09 ± 3.14 to 76.06 ± 6.20 MPa (~ 253%) and from 1.12 ± 0.33 to 8.90 ± 0.97 GPa (~ 795%), respectively. Moreover, the Ag-CNT film exhibits excellent near-field shielding performance, which can effectively block wireless transmission. This innovative approach provides an effective route to further apply macroscopic CNT assemblies to future portable and wearable electronic devices.

Enhancing the Chemical Stability of MXene Through Synergy of Hydrogen Bond and Coordination Bond in Aqueous Solution.

MXenes with unique physicochemical properties have shown substantial potential in electromagnetic interference (EMI) shielding. However, the chemical instability and mechanical fragility of MXenes has become a major hurdle for their application. Abundant strategies have been dedicated to improving the oxidation stability of colloidal solution or mechanical properties of films, which always come at the expense of electrical conductivity and chemical compatibility. Here, hydrogen bond (H-bond) and coordination bond are employed to achieve chemical and colloidal stability of MXenes (0.1 mg mL-1 ) by occupying the reaction sites of Ti3 C2 Tx attacking of water and oxygen molecules. Compared to the Ti3 C2 Tx , the Ti3 C2 Tx modified with alanine via H-bond shows significantly improved oxidation stability (at room temperature over 35 days), while the Ti3 C2 Tx modified with cysteine by synergy of H-bond and coordination bond can be maintained even after 120 days. Simulation and experimental results verify the formation of H-bond and Ti-S bond by a Lewis acid-base interaction between Ti3 C2 Tx and cysteine. Furthermore, the synergy strategy significantly improves the mechanical strength of the assembled film (up to 78.1 ± 7.9 MPa), corresponding the increment of 203% compared to untreated one, almost without compromising the electrical conductivity and EMI shielding performance.

[Changes of CK-MB and HSP 60 in electrical-injuried rats].

OBJECTIVE: To investigate the changes of creatine kinase-MB (CK-MB) and heat shock protein 60 (HSP 60) in rats without electric marks after electric injury, to identify the relationship of the CK-MB, HSP 60 and the time of electric injuries, and to evaluate the damage to cells after electric injury. METHODS: The animal model of electric injury without electric marks was established by alternating current (voltage 110 V). Automatic biochemistry analyzer was used to detect the serum CK-MB and immunohistochemical staining technology was used to analyze the tissues of myocardium and left lobe of liver. RESULTS: The amount of serum CK-MB was increased when the rats were injuried, and reached the peak at 30min. Then the amount of CK-MB began to decrease and showed a slight downward trend in 3-5 h after electric injury, and leveled off at 6 h. Immunohistochemistry staining also showed the changes of HSP 60 of rats' myocardial cells and hepatic cells regularly after electric injury. CONCLUSION: The regular changes of serum CK-MB and tissular HSP 60 in rats can be used to diagnosis electric injury and assess the injury of internal organs after the electric injury without electric marks.

Application of a reversed-phase ionic liquid dispersive liquid-liquid microextraction method for the extraction and preconcentration of domoic acid from urine samples.

A simple and efficient sample extraction and preconcentration method based on reversed-phase ionic liquid dispersive liquid-liquid microextraction (RP-IL-DLLME) had been developed and used to quantify the domoic acid in human urine samples. The analysis was performed by ultra-performance liquid chromatography and photodiode array detection. During the procedure, hydrophilic ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [C4mim] BF4 as dispersive solvent and NaOH solution was chosen as extraction solvent. Some important parameters in the method were investigated to get high enrichment factors. Under optimal conditions, the linearity of the method was in the range of 0.1-10 ng mL-1 and the correlation coefficient was above 0.9996. The relative standard deviations (RSDs) of the developed methods for intra-day (n = 5) and inter-day (n = 5) precision ranged from 1.9 to 3.9%. Meanwhile, limit of detection (LOD) was 0.03 ng mL-1(S/N = 3) and that of quantification (LOQ) was 0.1 ng mL-1(S/N = 10) with the enrichment factors (EF) being 230. Eventually, the proposed method was successfully applied to the determination of Dominic acid in human urine samples.

3-Ethyl 5-methyl 4-(2,3-dichloro-phen-yl)-2,6-dimethyl-pyridine-3,5-dicarboxyl-ate.

In the title compound, C(18)H(17)Cl(2)NO(4), an oxidation product of felodipine, the dihedral angle between the benzene and pyridine rings is 75.3 (4)°. The crystal structure is stabilized by intermolecular C-H⋯O interactions.

5-Methyl 3-(2-methyl-prop-3-yl) 2,6-di-methyl-4-(2-nitro-sophen-yl)pyridine-3,5-dicarboxyl-ate.

In the title compound, C(20)H(22)N(2)O(5), a photo-degradation product of the hypertension drug nisoldipine, the dihedral angle between the nitro-sophenyl ring and the pyridine ring is 75.7 (3)°. In the crystal structure, weak C-H⋯O hydrogen bonds help to establish the packing.

[Inhibitory effects of pretreatment with Buyanghuanwu decoction on inflammatory cytokine expressions in the kidneys of rats after induction of brain death].

OBJECTIVE: To observe the inhibitiory effects of pretreatment with Buyanghuanwu decoction (BYHWT) on inflammatory cytokine expressions in the kidneys and the level of reactive oxygen species (ROS) by peripheral blood neutrophils of rats after induction of brain death (BD), and to investigate the effect of BYHWT on the improvement of kidney quality from BD donor. METHODS: 30 male Wistar rats were randomly divided into 3 groups: control group, BD model group and BYHWT group. 6 hours after successful onset of brain death,only the BD rats whose mean arterial blood pressure were higher than 80 mmHg were accepted as donors. Kidneys were harvested and peripheral blood was taken from BD rats. RT-PCR was used to detect the expressions of TNF-a and IL-lpfl mRNA. Western blot was adopted to analyze the expressions of both TNF-alpha and IL-lp protein,and the expression of phosphorylated p38 mitogen-activated protein kinase (p-p38MAPK). Reactive oxygen species( ROS) in the peripheral blood neutrophils were labeled with CM-H2DCFDA and then detected with Flow Cytometry. RESULTS: The expressions of both TNF-alpha and IL-1beta mRNA and protein, and the p-p38MAPK proteins all significantly increased in BD group compared with control group (P < 0.01). However, those in BYHWT group statistically decreased compared with BD group (P < 0.05), but they significantly increased in comparison with control group (P < 0.01). There was a close relation between the expression of p-p38MAPK protein and the expressions of both TNF-a and IL-1beta mRNA and protein. ROS level significantly increased in BD group (P < 0.05 ), whereas it significantly decreased in BYHWT group (P < 0.05). There was no statistically significant difference between BYHWT group and control group (P > 0.05). CONCLUSION: Pretreatment of the rats with BYHWT prior to the induction of rat brain death, can significantly suppress the expressions of inflammatory cytokines and ROS level in the kidneys of rats from BD. It might be related to the blockage of key target points in p38MAPK signaling pathway. Therefore pretreatment with BYHWT could hopefully be an ideal way to improve the quality of kidneys from brain dead donors prior to transplantation.

Determination of isoquercitrin in rat plasma by high performance liquid chromatography coupled with a novel synergistic cloud point extraction.

A novel improved preconcentration method known as synergistic cloud point extraction was established for isoquercitrin preconcentration and determination in rat plasma prior to its determination by high performance liquid chromatography. Synergistic cloud point extraction greatly simplified isoquercitrin extraction and detection. This method was accomplished at room temperature (about 22°C) in 1min with the nonionic surfactant Tergitol TMN-6 as the extractant, n-octanol as cloud point revulsant and synergic reagent. Parameters that affect the synergistic cloud point extraction processes, such as the concentrations of Tergitol TMN-6, volume of n-octanol, sample pH, salt content and extraction time were investigated and optimized. Under the optimum conditions, the calibration curve for the analyte was linear in the range from 5 to 500ngmL-1 with the correlation coefficients greater than 0.9996. Meanwhile, limit of detection (S/N=3) was less than 1.6ngmL-1 and limit of quantification (S/N=10) was less than 5ngmL-1. It demonstrated that the method can be successfully applied to the pharmacokinetic investigation of isoquercitrin.

Determination of enantiomeric excess for 2,3-dihydroxy-3-phenylpropionate compounds by capillary electrophoresis using hydroxypropyl-beta-cyclodextrin as chiral selector.

A new capillary zone electrophoresis (CZE) method was developed to separate three chiral 2,3-dihydroxy-3-phenylpropionate enantiomers using neutral hydroxypropyl-beta-CD (HP-beta-CD) as chiral selector and borate as background electrolyte. The results showed that HP-beta-CD exhibited good enantioselectivity and high resolution was achieved under the optimum condition of pH 10.3, 200 mM borate buffer containing 6% methanol and 50 mM HP-beta-CD at 15 kV and 20 degrees C within 16 min. The precision of the method was <0.9% for migration time and 4.5% for corrected peak area. In addition, the developed method was successfully applied to the determination of enantiomeric excess (ee) of synthetic 2,3-dihydroxy-3-phenylpropionate samples. With this method, low as 0.2% impurity of the undesirable enantiomer in the presence of high amount of target enantiomer was determined. The results demonstrated that the proposed CZE method is a simple and useful technique and is applicable to ee assay of 2,3-dihydroxy-3-phenylpropionate enantiomers.