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1.
Zhen Ci Yan Jiu ; 49(4): 367-375, 2024 Apr 25.
Artículo en Inglés, Chino | MEDLINE | ID: mdl-38649204

RESUMEN

OBJECTIVES: To investigate the effect of electroacupuncture (EA) on Rho/Rho-associated coiled-coil-forming kinases (ROCK) signaling pathway of uterus tissue in rats with dysmenorrhea, so as to explore the underlying mechanism of EA treating primary dysmenorrhea (PD) and uterine smooth muscle spasm, and to observe whether there is a difference in the effect of meridian acupoints in Conception Vessel (CV) and Governer Vessel (GV). METHODS: Sixty female SD rats were randomly divided into saline, model, CV, GV, and non-acupoint groups, with 12 rats in each group. The dysmenorrhea model was established by subcutaneous injection of estradiol diphenhydrate combined with intraperitoneal injection of oxytocin (OT). EA (2 Hz) was applied to "Qihai" (CV6) and "Zhongji" (CV3) for CV group, "Mingmen" (GV4) and "Yaoshu" (GV2) for GV group, "non-acupoint 1" and "non-acupoint 3" on the left side for non-acupoint group, and manual acupuncture was applied to "Guanyuan" (CV4) for CV group, "Yaoyangguan" (GV3) for GV group, "non-acupoint 2" on the left side for non-acupoint group. The treatment was conducted for 20 min each time, once daily for 10 days. The writhing score was evaluated. The smooth myoelectric signals of rats' uterus in vivo were recorded by multi-channel physiological recorder. The uterine histopathological changes were observed by HE staining. The contents of prostaglandin F2α (PGF2α), OT and calcium ion (Ca2+) in uterine tissue of rats were detected by ELISA. The protein and mRNA expression levels of smooth muscle 22-α (SM22-α), RhoA and ROCKⅡ in uterine tissue were detected by Western blot and fluorescence quantitative PCR, respectively. RESULTS: Compared with the saline group, the writhing score of rats in the model group was increased (P<0.01), the amplitude voltage of uterine smooth muscle in vivo was elevated (P<0.01), the contents of PGF2α, OT and Ca2+, the protein and mRNA expression of SM22-α, RhoA and ROCK Ⅱ in uterine tissue were all increased (P<0.01). Compared with the model and the non-acupoint groups, the writhing scores of the CV and the GV groups were decreased (P<0.01, P<0.05), the amplitude voltage of uterine smooth muscle was decreased (P<0.01), the contents of PGF2α, OT and Ca2+ in uterine tissue were decreased (P<0.01, P<0.05), and the protein expression and mRNA expression of SM22-α, RhoA and ROCKⅡ in uterine tissue were decreased (P<0.01, P<0.05). HE staining showed extensive exfoliation of uterine intima with severe edema and increased glandular secretion in the model group, which was alleviated in the CV and GV groups. CONCLUSIONS: EA at acupoints of CV and GV can significantly reduce the writhing score, uterine smooth muscle amplitude voltage, pathological injury degree of uterus, and relieve spasm of uterine smooth muscle in dysmenorrhea rats, which may be related to its effect in regulating PGF2α and OT contents, inhibiting the Rho/ROCK signaling pathway, and reducing the SM22-α, RhoA, ROCKⅡ protein and mRNA expression, and Ca2+ content in uterine tissue.


Asunto(s)
Puntos de Acupuntura , Dismenorrea , Electroacupuntura , Ratas Sprague-Dawley , Transducción de Señal , Útero , Quinasas Asociadas a rho , Animales , Femenino , Dismenorrea/terapia , Dismenorrea/metabolismo , Dismenorrea/genética , Quinasas Asociadas a rho/metabolismo , Quinasas Asociadas a rho/genética , Ratas , Humanos , Útero/metabolismo , Músculo Liso/metabolismo , Espasmo/terapia , Espasmo/genética , Espasmo/metabolismo , Espasmo/fisiopatología
2.
Open Life Sci ; 18(1): 20220742, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37941786

RESUMEN

Ectopic thyroid is a rare malformation induced by a migration defect in the developing gland during embryogenesis. In 90% of cases, the ectopic thyroid is located in the lingual region, whereas it is extremely rare in the abdominal cavity, particularly in the pancreas. A 50-year-old female patient presented to the Taizhou First People's Hospital with a complaint of recurrent mid-lower abdominal pain and diarrhea for approximately a month. The abdominal computed tomography scan revealed a space-occupying lesion with abundant blood supply in the head of the pancreas during the consultation. This led to the suspicion of a neuroendocrine tumor. The doctor considered that this lesion in the head of the pancreas could be responsible for the patient's incontinence. A laparoscopic pancreaticoduodenectomy was performed after relevant tests were undertaken and contraindications were ruled out. The patient was diagnosed with ectopic thyroid of the pancreas through postoperative pathology. Ectopic thyroid can be considered in middle-aged and elderly women who present with a mass with abundant blood supply and an unknown diagnosis. Subsequent treatments should be decided after fine-needle aspiration cytology.

3.
Zhongguo Zhen Jiu ; 43(9): 1042-7, 2023 Sep 12.
Artículo en Chino | MEDLINE | ID: mdl-37697880

RESUMEN

OBJECTIVE: To observe the skin surface microcirculation of acupoints of conception vessel, governor vessel and thoroughfare vessel in patients with primary dysmenorrhea using laser speckle contrast imaging (LSCI), and provide acupoint selection basis of acupuncture-moxibustion for primary dysmenorrhea. METHODS: Ninety-nine healthy female college students with regular menstrual cycles (normal group) and 94 female college students with primary dysmenorrhea (dysmenorrhea group) were recruited. Before menstrual period, on the first day of menstruation, and on the third day after menstruation, LSCI was used to observe the surface microcirculation at the abdominal acupoints of conception vessel, i. e. Yinjiao (CV 7), Qihai (CV 6), Shimen (CV 5), Guanyuan (CV 4), Zhongji (CV 3) and Qugou (CV 2), acupoints of thoroughfare vessel, i. e. Huangshu (KI 16), Zhongzhu (KI 15), Siman (KI 14), Qixue (KI 13), Dahe (KI 12), Henggu (KI 11) and acupoints of lumbosacral region of governor vessel, i. e. Xuanshu (GV 5), Mingmen (GV 4), Yaoyangguan (GV 3), Yaoshu (GV 2) as well as two non-acupoints. RESULTS: Before menstrual period, there was no significant difference in the surface blood perfusion of the acupoints between the dysmenorrhea group and the normal group (P>0.05). On the first day of menstruation, the surface blood perfusion of Xuanshu (GV 5), Mingmen (GV 4), Yaoyangguan (GV 3) and right Huangshu (KI 16) in the dysmenorrhea group was higher than that in the normal group (P<0.05, P<0.01). On the third day after menstruation, the surface blood perfusion of the right Henggu (KI 11) in the dysmenorrhea group was lower than that in the normal group (P<0.05). CONCLUSION: In patients with primary dysmenorrhea, on the first day of menstruation, the surface blood perfusion of Xuanshu (GV 5), Mingmen (GV 4), Yaoyangguan (GV 3) of governor vessel, and the right Huangshu (KI 16) of thoroughfare vessel is increased, while on the third day after menstruation, the surface blood perfusion of the right Henggu (KI 11) of thoroughfare vessel is decreased. These findings might provide a basis for acupoint selection in the acupuncture-moxibustion treatment of primary dysmenorrhea.


Asunto(s)
Terapia por Acupuntura , Dismenorrea , Humanos , Femenino , Microcirculación , Dismenorrea/terapia , Ciclo Menstrual , Puntos de Acupuntura
4.
Chin J Integr Med ; 28(12): 1096-1104, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36327047

RESUMEN

OBJECTIVE: To evaluate the effects of auricular acupoint bloodletting (AB) and auricular acupressure (AA) on sleep quality and the levels of melatonin (MT), glutamic acid (Glu), and γ -aminobutyric acid (GABA) in college students with primary insomnia, and to explore the possible mechanism. METHODS: Totally 74 college students at Hebei University of Chinese Medicine with primary insomnia were selected from October 2019 to October 2020. All patients were assigned to AB+AA group (37 cases, received combination of AB and AA) and AA group (37 cases, received only AA on the same acupoints) by a random number table. Each group was treated twice a week for 4 weeks. The Pittsburgh Sleep Quality Index (PSQI) score, Chinese medicine (CM) syndrome score, total effective rate, serum concentrations of MT, Glu, and GABA, and Glu/GABA ratio were compared between the two groups after treatment and at follow-up. The safety of therapy was also evaluated. RESULTS: After 4-week treatment, the total scores of PSQI, each PSQI component score, and the CM syndrome scores in both groups all decreased (P<0.05); the serum MT concentrations in both groups all increased (P<0.05). The concentrations of Glu and GABA in the AB+AA group were significantly higher than those in the AA group after treatment (P<0.05). However, there was no significant difference in the ratio of Glu/GABA in both groups before and after treatment (P>0.05). At follow-up, the CM syndrome score in the AB+AA group was significantly lower than that in the AA group (P<0.05). There was no significant difference between the two groups in total effective rates and adverse events (P>0.05). CONCLUSIONS: Both AB+AA and AA can relieve insomnia symptoms, but a stronger long-term effect were observed for AB+AA. AB+AA can promote the secretion of MT, increase the levels of Glu and GABA more effective than AA, and regulate their imbalance, and thus it may be benificial for treating insomnia.


Asunto(s)
Acupresión , Trastornos del Inicio y del Mantenimiento del Sueño , Humanos , Puntos de Acupuntura , Venodisección , Trastornos del Inicio y del Mantenimiento del Sueño/terapia , Calidad del Sueño , Síndrome , Estudiantes , Ácido gamma-Aminobutírico
5.
Zhongguo Zhen Jiu ; 42(6): 629-33, 2022 Jun 12.
Artículo en Chino | MEDLINE | ID: mdl-35712946

RESUMEN

OBJECTIVE: To observe the clinical efficacy of different treatment frequency of auricular bloodletting combined with auricular point sticking for acne vulgaris. METHODS: A total of 90 patients with acne vulgaris were randomized into a treatment group 1 (30 cases, 2 cases dropped off), a treatment group 2 (30 cases, 4 cases dropped off) and a treatment group 3 (30 cases, 5 cases dropped off). Combination therapy of auricular bloodletting and auricular point sticking at Fei (CO14), Shenmen (TF4), Neifenmi (CO18) and Shenshangxian (TG2p) were given once a week, twice a week and 3 times a week in the treatment group 1, the treatment group 2 and the treatment group 3 respectively, 4 weeks were as one course and totally 3 courses were required in the 3 groups. Before treatment and after 1, 2, 3 courses of treatment, the scores of global acne grading system (GAGS), skin lesion and quality of life-acne (QoL-Acne) were observed, the clinical efficacy was evaluated after 3 courses of treatment and the recurrence rate was evaluated in follow-up of 1 month after treatment in the 3 groups. RESULTS: Compared before treatment, the scores of GAGS and skin lesion were decreased at each time point in the 3 groups (P<0.05), the QoL-Acne scores were increased after 1 course of treatment in the treatment group 3 and after 2, 3 courses of treatment in the 3 groups (P<0.05). There were no statistical differences in scores of GAGS, skin lesion and QoL-Acne among the 3 groups (P>0.05). There were no statistical differences in effective rate and recurrence rate among the 3 groups (P>0.05). CONCLUSION: Different frequency of auricular bloodletting combined with auricular point sticking have similar efficacy in treating acne vulgaris, all can improve the skin lesion and quality of life in patients with acne vulgaris, and have a cumulative effect and good long-term curative effect.


Asunto(s)
Acné Vulgar , Acupuntura Auricular , Acné Vulgar/terapia , Puntos de Acupuntura , Venodisección , Humanos , Calidad de Vida , Resultado del Tratamiento
6.
J Mol Model ; 28(3): 72, 2022 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-35226197

RESUMEN

Hydrogen peroxide (H2O2) is used as a fuel and propellant in fuel cells and rockets due to its prominent oxidizing and combustion properties. In addition, hydrogen peroxide, as the energetic material with the simplest molecular structure, exhibits general detonation performance under external stimulation. Based on the first-principle method, we calculated the two crystal structure, electronic properties related to sensitivity closely, optical properties of pure hydrogen peroxide, and 48wt.% hydrogen peroxide (H6O4) under pressure. We found that the band gaps of H2O2 and H6O4 become larger under pressure and the former is larger than the latter; neither has the tendency of metallization phase change. The added peak II of TDOS from H6O4 compared with H2O2 come from molecular H2O in crystal structure. The pressure-induced peak (peak 2 and peak II of TDOS from H2O2 and H6O4) splitting is caused by changes (stronger) in the intermolecular hydrogen bond environment in the crystal under pressure. The specific macroscopic optical properties have the characteristics of overall blue-shift under pressure, which is due to the blueshift of the conduction band and the increase of the band gap. We hope to provide some reference and guidance for deeper future research.

7.
J Mol Model ; 27(10): 307, 2021 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-34591190

RESUMEN

Due to the diversity of solid nitrogen structure, its phase transition has been a hot topic for many scientists. Herein, we first studied the structural softening of rhombohedral solid nitrogen under pressure using first-principles calculations. Then, a new criterion, Egret criterion, was proposed to predict the whole process from beginning to end of structural phase transition of solid nitrogen. Based on the discussion of acoustic phonons, we concluded that the phase transition of rhombohedral solid nitrogen starts from k-point F along the [- 1, - 1, 0] direction in a-axis, and the structural phase transition velocity is slow. Also, we use the Egret criterion proposed by us to predict the emergence of ξ-N2 and the stability of ξ-N2 at 17 GPa and 22 GPa, respectively, and this result is in good agreement with the phase diagram of nitrogen.

8.
J Mol Model ; 27(9): 254, 2021 Aug 18.
Artículo en Inglés | MEDLINE | ID: mdl-34406485

RESUMEN

The band structure, total density of states, and atomic orbit projected density of states analysis were performed to investigate HMX/NMP cocrystal by using the first-principles calculations. Results show that the HMX/NMP cocrystal is equipped with a direct band gap and the interactions between HMX and NMP molecules are rather weak. The O orbits hybridize with H orbits, and the parts of charge transform from H to O atoms by analyzing the DOS. The HMX/NMP cocrystal possesses three types of intermolecular interactions between HMX and NMP; these interactions and the arrangement of two molecules in the structure are the main reasons for the low sensitivity of the cocrystal. The C-H…O type hydrogen bond is the key role in forming the structure, and the strength of the hydrogen bond interaction for C-H…O-N is higher than that of C-H…O-C.

9.
J Mol Model ; 27(6): 187, 2021 May 26.
Artículo en Inglés | MEDLINE | ID: mdl-34037870

RESUMEN

In recent years, the important energetic material triaminoguanidinium nitrate (TAGN) has been widely used, and the process of synthesizing TAGN has become more and more perfect. However, there are relatively few theoretical studies on TAGN. This paper uses first-principles calculations to more systematically study the crystal structure, and electronic, vibrational, and thermodynamic properties of TAGN. The calculation results show that the calculated unit cell parameters are relatively consistent with the values obtained through X-ray diffraction experiments. This article describes in detail the state density of the valence electrons of each atom. By analyzing the vibrational properties of TAGN crystal, the vibration mode corresponding to each optical wave is obtained. At the same time, the vibration mode of each peak in the Raman spectrum and the infrared spectrum is described in detail. Then, the calculated value is compared with the experimental value; it can be seen that the error is relatively small. According to the vibration characteristics, a series of thermodynamic functions such as enthalpy (H), Debye temperature (Θ), free energy (F), and entropy (S) are calculated. These thermodynamic functions can provide a certain reference for future research.

10.
Sci Adv ; 6(51)2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33328240

RESUMEN

In chemical reactions, the breaking and formation of chemical bonds usually need external energy to overcome the activation barriers. Conventional energy delivery transfers energy from heating sources via various media, hence losing efficiency and inducing side reactions. In contrast, microwave (MW) heating is known to be highly energy efficient through dipole interaction with polar media, but how exactly it transmits energy to initiate chemical reactions has been unknown. Here, we report a rigorous determination of energy delivery mechanisms underlying MW-enabled rapid hydrothermal synthesis, by monitoring the structure and temperature of all the involved components as solid-liquid intercalation reaction occurs using in situ synchrotron techniques. We reveal a hitherto unknown direct energy transmission between MW irradiation source and the targeted reactants, leading to greatly reduced energy waste, and so the ultrafast kinetics at low temperature. These findings open up new horizons for designing material synthesis reactions of high efficiency and precision.

11.
Chem Commun (Camb) ; 56(3): 403-406, 2020 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-31821392

RESUMEN

CeO2-x quantum dots with massive oxygen vacancies are obtained by a one-step single molecular synthesis strategy. The yield of dimethyl carbonate from CO2 and methanol is more than 5 times that for commercial CeO2 nanoparticles.

12.
Math Biosci Eng ; 16(5): 3345-3367, 2019 04 18.
Artículo en Inglés | MEDLINE | ID: mdl-31499617

RESUMEN

The convolutional neural networks (CNN) applied in remote sensing scene classification have two common problems. One is that these models have large number of parameters, which causes over-fitting easily. The other is that the network is not deep enough, thus more abstract semantic information cannot be extracted. To solve these two problems, we propose a simple and efficient full convolutional network based on DenseNet for remote sensing scene classification. We construct a small number of convolutional kernels to generate a large number of reusable feature maps by dense connections, which makes the network deeper, but does not increase the number of parameters significantly. Our network is so deep that it has more than 100 layers. However, it has only about 7 million parameters, which is far less than the number of VGG's parameters. Then we incorporate an adaptive average 3D pooling operation in our network. This operation fixes feature maps of size 7 × 7 from the last DenseBlock to 1 × 1 and decreases the number of channels from 1024 to 512, thus the whole network can accept input images with different sizes. Furthermore, we design the convolutional layer instead of the fully connected layer that is used as a classifier usually, so that the output features of the network can be classified without flattening operation, which simplifies the classification operation. Finally, a good model is trained by exploiting pre-trained weights and data augmentation technology. Compared with several state-of-the-art algorithms, our algorithm improves classification performance significantly on UCM dataset, AID dataset, OPTIMAL-31 dataset and NWPU-RESISC45 dataset.

13.
J Am Chem Soc ; 140(39): 12484-12492, 2018 Oct 03.
Artículo en Inglés | MEDLINE | ID: mdl-30165740

RESUMEN

Metal (M) oxides are one of the most interesting and widely used solids, and many of their properties can be directly correlated to the local structural ordering within basic building units (BBUs). One particular example is the high-Ni transition metal layered oxides, potential cathode materials for Li-ion batteries whose electrochemical activity is largely determined by the cationic ordering in octahedra (e.g., the BBUs in such systems). Yet to be firmly established is how the BBUs are inherited from precursors and subsequently evolve into the desired ordering during synthesis. Herein, a multimodal in situ X-ray characterization approach is employed to investigate the synthesis process in preparing LiNi0.77Mn0.13Co0.10O2 from its hydroxide counterpart, at scales varying from the long-range to local individual octahedral units. Real-time observation corroborated by first-principles calculations reveals a topotactic transformation throughout the entire process, during which the layered framework is retained; however, due to preferential oxidation of Co and Mn over Ni, significant changes happen locally within NiO6 octahedra. Specifically, oxygen loss and the associated symmetry breaking occur in NiO6; as a consequence, Ni2+ ions become highly mobile and tend to mix with Li, causing high cationic disordering upon formation of the layered oxides. Only through high-temperature heat treatment, Ni is further oxidized, thereby inducing symmetry reconstruction and, concomitantly, cationic ordering within NiO6 octahedra. Findings from this study shed light on designing high-Ni layered oxide cathodes and, more broadly, various functional materials through synthetic control of the constituent BBUs.

14.
ACS Appl Mater Interfaces ; 9(34): 29021-29029, 2017 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-28791868

RESUMEN

A niobium-doped titanium dioxide (Nb:TiO2, NTO) film is a promising candidate material for indium-free transparent conductive oxide (TCO) films. It is challenging and interesting to control (004)-oriented growth to decrease resistivity. In this work, NTO films with different fractions of preferential (004) orientation (η(004)) were controllably prepared by direct current sputtering. Notably, the direction of local-ordering of ions-packing could be adjusted by slightly changing the angle between the sputtering source and the glass substrate, which is identified as a key factor to determine the growth direction of a columnar crystal as well as the η(004) of films. Hall effect measurements indicate that NTO films with the highest η(004) present the lowest resistivity (6.4 × 10-4 Ω cm), which originates from super-high carrier concentration (2.9 × 1021 cm-3) and mobility (3.4 cm2 V-1 s-1). The corresponding low sheet resistance (10.3 Ω sq-1) makes it a potential material for commercial TCO films. We also observe that films with higher η(004) show lower transmittance in the near-infrared region.

15.
Adv Mater ; 29(39)2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28841754

RESUMEN

Nickel-rich layered transition metal oxides, LiNi1-x (MnCo)x O2 (1-x ≥ 0.5), are appealing candidates for cathodes in next-generation lithium-ion batteries (LIBs) for electric vehicles and other large-scale applications, due to their high capacity and low cost. However, synthetic control of the structural ordering in such a complex quaternary system has been a great challenge, especially in the presence of high Ni content. Herein, synthesis reactions for preparing layered LiNi0.7 Mn0.15 Co0.15 O2 (NMC71515) by solid-state methods are investigated through a combination of time-resolved in situ high-energy X-ray diffraction and absorption spectroscopy measurements. The real-time observation reveals a strong temperature dependence of the kinetics of cationic ordering in NMC71515 as a result of thermal-driven oxidation of transition metals and lithium/oxygen loss that concomitantly occur during heat treatment. Through synthetic control of the kinetic reaction pathway, a layered NMC71515 with low cationic disordering and a high reversible capacity is prepared in air. The findings may help to pave the way for designing high-Ni layered oxide cathodes for LIBs.

16.
Chemistry ; 23(46): 10978-10982, 2017 Aug 16.
Artículo en Inglés | MEDLINE | ID: mdl-28685879

RESUMEN

To develop new mid-infrared (MIR) nonlinear optical (NLO) materials, which can overcome the low laser damage threshold (LDT) of the commercial MIR-NLO crystals (AgGaS2 , AgGaSe2 and ZnGeP2 ) and simultaneously keep the large NLO susceptibility, is necessary for high-power MIR laser frequency conversion technology. To improve the LDT, a new strategy of increasing lattice stability was adopted. Here, the strongly covalent structural unit of the PS4 tetrahedron was introduced into AgGaS2 (AGS), and that led to the isolation of the first compound in AgI -GaIII -PV -S system, namely, AgGa2 PS6 (Cc). It retains a large SHG efficiency (1.0×AGS) with phase-matchable ability, and also exhibits an improved LDT (5.1×AGS), indicating AgGa2 PS6 is a new promising MIR-NLO crystal. Moreover, a novel 3D framework of [Ga2 PS6 ]- , with triangular-shaped channels, as well as interesting single triangular geometry of AgS3 -both of which are very rare in reported sulfides-was discovered in AgGa2 PS6 . Furthermore, theoretical calculations, and lattice energy and thermal expansions analyses suggest that the PS4 group makes a large contribution to the large SHG efficiency and high LDT.

17.
Chem Commun (Camb) ; 53(46): 6239-6242, 2017 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-28537618

RESUMEN

Glass frits play an important role in the front contact electrodes of crystalline silicon (c-Si) solar cells. In this work, we developed a novel glass frit by doping Ag into a glass frit in the process of high-temperature synthesis. When the Ag paste including this novel glass frit was used as the front contact electrode of silicon solar cells, the conversion efficiency of poly-crystalline silicon (pc-Si) solar cells was improved by 1.9% compared to the glass frit without Ag. Through SEM characterisation and calculation of series resistance, we further found that the interface between Ag and Si was improved and the contact resistance of Ag and Si was greatly reduced, which were believed to be responsible for the improvement of solar cell performance. This work shows great guidance significance to develop novel and highly efficient commercial glass frits applied in solar cells in the future.

18.
Inorg Chem ; 56(2): 962-973, 2017 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-28055200

RESUMEN

Quaternary metal thiophosphates containing second-order Jahn-Teller distorted d10 Ag+ and lone-pair cations, Ag3Bi(PS4)2 (1), Ag7Sn(PS4)3 (2), and Ag7Pb(PS4)3 (3), were obtained by solid-state synthesis. The structural frameworks of 2 and 3 feature an infinite 1-D interchiral double helix ∞1(Ag3P2S11), which is rare in inorganic compounds. Compound 3 undergoes a significant first-order structural phase transition from monoclinic to hexagonal at ∼204 °C. This can be ascribed to the significant mismatch in the expansion coefficients between Pb-S (Ag-S) and P-S bonds evaluated by bond valence theory. The three compounds are Ag+ ionic conductors, and Ag+ ion migration pathways are proposed by calculating maps of low bond valence mismatch. Moreover, the optical properties of the three compounds were studied, and electronic structure calculations were performed. The combination of second-order Jahn-Teller distorted d10 cation and lone-pair cation provides a new strategy to explore new metal thiophosphates with interesting structures and promising properties.

19.
ACS Omega ; 2(1): 346-352, 2017 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-31457235

RESUMEN

For designing energetic materials (EMs), the most challenging issue is to achieve a balance between energetic performance and reliable stability. In this work, we employed an efficient and convenient method to synthesize a new class of EMs: nitrogen-rich tetranuclear metal complexes [M(Hdtim)(H2O)2]4 (M = Zn 1, Mn 2; H3dtim = 1H-imidazol-4,5-tetrazole) with the N content of >46%. The structural analyses illustrate that isomorphous compounds 1 and 2 feature isolated hollow ellipsoid tetranuclear units, which are linked by both π-π interactions and hydrogen-bonding interactions to give a 3D supramolecular architecture. Compounds 1 and 2 exhibit prominent energetic characteristics: excellent detonation performances and reliable thermal, impact, and friction stabilities. Being nitrogen-rich tetrazolate compounds, the enthalpies of combustion of 1 (-11.570 kJ g-1) and 2 (-12.186 kJ g-1) are higher than those of classical EMs, RDX and HMX, and they possess high positive heats of formation. Sensitivity tests demonstrate that 1 and 2 are insensitive to external mechanical action. Excellent energetic performances and low sensitivities promote 1 and 2 to serve as a new class of promising EMs with a desirable level of safety.

20.
ACS Appl Mater Interfaces ; 8(40): 26722-26729, 2016 Oct 12.
Artículo en Inglés | MEDLINE | ID: mdl-27632809

RESUMEN

Specific capacity and cyclic performance are critically important for the electrode materials of rechargeable batteries. Herein, a capacity boost effect of Li- and Na-ion batteries was presented and clarified by nitrogen-doped graphene sheets. The reversible capacities progressively increased from 637.4 to 1050.4 mAh g-1 (164.8% increase) in Li-ion cell tests from 20 to 185 cycles, and from 187.3 to 247.5 mAh g-1 (132.1% increase) in Na-ion cell tests from 50 to 500 cycles. The mechanism of the capacity boost is proposed as an electrochemical induced cascading evolution of graphitic N to pyridinic and/or pyrrolic N, during which only these graphitic N adjacent pyridinic or pyrrolic structures can be taken precedence. The original and new generated pyridinic and pyrrolic N have strengthened binding energies to Li/Na atoms, thus increased the Li/Na coverage and delivered a progressive capacity boost with cycles until the entire favorable graphitic N transform into pyridinic and pyrrolic N.

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