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1.
Artigo em Inglês | MEDLINE | ID: mdl-32517165

RESUMO

Engaging in prosocial behavior is considered an effective way to increase happiness in a sustainable manner. However, there is insufficient knowledge about the conditions under which such a happiness effect occurs. From a person-activity congruence perspective, we proposed that an individual's eudaimonic orientation moderates the effect of prosocial behavior on happiness, whereas hedonic orientation does not. For this purpose, 128 participants were assigned to play a game in which half of them were explained the benevolence impact of playing the game (the benevolence condition), and the other half played the same game without this knowledge (the control condition). Participants' eudaimonic and hedonic orientations were assessed before the game, and their post-task happiness were measured after the game. The results showed that participants in the benevolence condition reported higher post-task positive affect than those in the control condition. Furthermore, this happiness effect was moderated by participants' eudaimonic orientation-participants with high eudaimonic orientation reaped greater benefits from benevolence, and their hedonic orientation did not moderate the relationship between benevolence and happiness. The importance of the effect of person-activity congruence on happiness is discussed, along with the implications of these findings for sustainably pursuing happiness.


Assuntos
Felicidade , Orientação , Prazer/fisiologia , Comportamento Social , Comportamento , Humanos , Relações Interpessoais , Personalidade , Filosofia , Teoria Psicológica , Virtudes
2.
J Mol Model ; 25(1): 25, 2019 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-30612197

RESUMO

The B3PW91/6-31G** theoretical method was carried out to optimize the structure of 12 polynitro imidazo [4,5-e] oxadiazolo [3,4-b] pyrazine compounds (two structural type). The influence of nitro groups on the structure, oxygen balance, density, heat of formation, detonation performances, and charge were investigated. The results showed that the oxygen balance, density, heat of formation, detonation velocity, detonation pressure, and detonation heat increased with different relationships when the number of nitro groups increased. The contribution of the dinitroethylene group to energy was greater than that of the nitroimino group. On the whole, the sensitivity of all compounds increased with the number of -NO2 groups, and the second type of compound is more sensitive because of more nitro groups. The alkaline of the amine will decrease with the increasing number of -NO2 groups, and nitrification action will become more difficult. Graphical abstract Polynitro imidazo [4, 5-e] oxadiazolo [3, 4-b] pyrazine compoundsᅟ.

3.
R Soc Open Sci ; 5(5): 172269, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29892410

RESUMO

The formation mechanism of pentazolate anion (PZA) is not yet clear. In order to present the possible formation pathways of PZA, the potential energy surfaces of phenylpentazole (PPZ), phenylpentazole radical (PPZ-R), phenylpentazole radical anion (PPZ-RA), PPZ and m-chloroperbenzoic acid (m-CPBA), p-pentazolylphenolate anion (p-PZPolA) and m-CPBA, and p-pentazolylphenol (p-PZPol) and m-CPBA were calculated by the computational electronic structure methods including the hybrid density functional, the double hybrid density functional and the coupled-cluster theories. At the thermodynamic point of view, the cleavages of C-N bonds of PPZ and PPZ-R need to absorb large amounts of heat. Thus, they are not feasible entrance for PZA formation at ambient condition. But excitation of PPZ and deprotonation of PPZ-RA probably happen before cleavage of C-N bond of PPZ at high-energy condition. As to the radical anion mechanism, the high accuracy calculations surveyed that the barrier of PZA formation is probably lower than that of dinitrogen evolution, but the small ionization potential of PPZ-RA gives rise to the unstable ionic pair of sodium PPZ at high temperature. In respect of oxidation mechanism, except for PPZ, the reactions of p-PZPolA and p-PZPol with m-CPBA can form PZA and quinone. The PZA formations have the barriers of about 20 kcal mol-1 which compete with the dinitrogen evolutions. The stabilities of PZA in both solid and gas phases were also studied herein. The proton prefers to transfer to pentazolyl group in the (N5)6(H3O)3(NH4)4Cl system which leads to the dissociation of pentazole ring. The ground states of M(N5)2(H2O)4 (M = Co, Fe and Mn) are high-spin states. The pentazolyl groups confined by the crystal waters in the coordinate compounds can improve the kinetic stability. As to the reactivity of PZA, it can be persistently oxidized by m-CPBA to oxo-PZA and 1,3-oxo-PZA with the barriers of about 20 kcal mol-1.

4.
J Phys Chem A ; 122(8): 2129-2134, 2018 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-29437398

RESUMO

As a significant stimulus, the external electric field (EEF) can change the decomposition mechanism and energy release of energetic materials (EMs). Hence, understanding the response of EMs to an EEF is greatly meaningful for their safe usage. Herein, the structural arrangement, a crucial factor in the impact sensitivity and detonation performance of EMs, under the EEF ranging from 0.0 to 0.5 V/Å was investigated via molecular dynamics simulation. Nitromethane (NM) was taken as a case study due to the simple structure. The simulation results show that there exists a critical EEF strength between 0.2 and 0.3 V/Å, which can induce the transition of NM molecules from relatively disordered distribution to solidlike ordered and compacted arrangement with a large density. In this ordered structure, NM dipoles are aligned in a head-to-tail pattern parallel to the EEF direction because of the favored dipole-dipole interactions and weak C-H···O hydrogen bonds. As the EEF strength is enhanced, the potential energy and cohesive energy density of the NM system gradually decrease and increase, respectively, indicative of high thermodynamics stability of ordered arrangement. The results reported here also shed light on the potential of the EEF to induce the nucleation and crystallization to explore new polymorphs of EMs.

5.
J Mol Model ; 23(12): 340, 2017 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-29124479

RESUMO

In order to discover more potential high energy compounds, five computer-aided design methods were founded, and 20 high energetic compounds based on the 1,2,3,4-tetrazine-1,3-dioxide frame were designed. The first step of computer-aided design methods was to design new frame M. Three combination rules were invented, they were simple double-points rule, complicated double-points rule, and complicated multi-points rule. The second step of computer-aided design methods was to design 1,2,3,4-tetrazine 1,3-dioxides derivants by connecting M to 1,2,3,4-tetrazine-1,3-dioxides. Two combination rules were invented, they were simple single-points rule and double-points rule. All the structures are ring-fused or caged compounds including 1,2,3,4-tetrazine-1,3-dioxide. In these compounds, almost half of them have positive or zero oxygen balances, and the nitrogen contents of 17 compounds are over 40%. The densities and detonation velocities of all compounds are over 1.98 g cm-3 and 9500 m s-1 respectively. -N = N- group and -NO2 group have a major contribution to enthalpy of formation, detonation heat, and power index. -O- group and -ONO2 group have the main contribution to density, detonation velocity, and detonation pressure.

6.
J Phys Chem B ; 121(29): 7140-7146, 2017 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-28696111

RESUMO

To understand the crystal-solvent interfacial interactions on the molecular scale, the interfaces between three solvents, that is, acetone, γ-butyrolactone, and cyclohexanone, and three growth faces of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) crystal have been investigated with the aid of theoretical chemistry. The results show that the structural features of crystal faces play a critical role in the energetic, structural, and dynamic properties at the interfaces. For each solvent, the same change trend of some properties among the three faces of HMX crystal is observed, including adsorption affinity, local mass density, and solvent diffusion. For example, the rate of solvent diffusion at the three faces ranks as (011) > (110) > (020) regardless of solvent species. This can be attributed to the similar adsorption sites for solvent incorporation at the same face, which are concentrated at the cavities formed by surficial HMX molecules.

7.
J Mol Graph Model ; 74: 38-43, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28349878

RESUMO

Molecular dynamics simulations have been performed to understand the adsorption behavior of acetone (AC) solvent at the three surfaces of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctan (HMX) crystal, i.e. (011), (110), and (020) faces. The simulation results show that the structural features and electrostatic potentials of crystal faces are determined by the HMX molecular packing, inducing distinct mass density distribution, dipole orientation, and diffusion of solvent molecules in the interfacial regions. The solvent adsorption is mainly governed by the van der Waals forces, and the crystal-solvent interaction energies among three systems are ranked as (020)≈(110)>(011). The adsorption sites for solvent incorporation at the crystal surface were found and visualized with the aid of occupancy analysis. A uniform arrangement of adsorption sites is observed at the rough (020) surface as a result of ordered adsorption motif.


Assuntos
Acetona/química , Azocinas/química , Solventes/química , Adsorção , Sítios de Ligação , Cristalização , Simulação de Dinâmica Molecular , Propriedades de Superfície
8.
J Mol Model ; 22(4): 83, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26983612

RESUMO

In order to study the effects of N-oxide on structure and performance, six categories of energetic compounds were systemically investigated. The results indicated that the C-C bonds in the rings were shortened, and the C-N bonds close to the N → O bond were elongated when N atoms was oxidized to form N → O bonds. N → O bonds can increase the densities of most categories of compounds, and the increment will increase with the number of N → O bonds. As to their detonation performances, almost all categories of compounds had an increased trend, except for some NO2-, NHNO2- and ONO2-substituted compounds. The contribution of 1,2,3,4-tetrazine and 1,2,4,5-tetrazine to performances was better than that of pyrazine and [1,2,5] oxadiazolo [3,4-b] pyrazine on the whole, and the groups, especially energetic groups, made a huge contribution to performance. When R was a NH2 or ONO2 group, all compounds had lower impact sensitivities, and thus represent candidates for novel energetic compounds. However, other than the sixth category of compounds, all compounds had higher impact sensitivities when R was a NO2 or NHNO2 group, and have little significance in application.


Assuntos
Substâncias Explosivas/química , Compostos Heterocíclicos com 1 Anel/química , Óxidos de Nitrogênio/química , Pirazinas/química , Teoria Quântica , Relação Estrutura-Atividade , Termodinâmica
9.
Chemphyschem ; 17(4): 541-7, 2016 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-26677195

RESUMO

The reaction pathway of the formation of 3,4-dinitrofuroxan from glyoxime is theoretically investigated under experimental conditions with 25 % nitric acid and dinitrogentetroxide reagents to clarify the mechanism of formation of a furoxan ring by glyoxime. The geometric configurations of minima and transition-state species are optimized at the (U)B3LYP/6-311++G** level. The CCSD(T) and CASSCF(10e,8o)/CASSCF(9e,8o) single-point energy corrections at the same level are performed on top of the optimized geometries. A subsequent dynamic correlation by using NEVPT2/6-311++G**-level single-point energy calculations based on the CASSCF results is also performed to obtain accurate energy values. The formation reaction is analyzed from two processes: glyoxime nitration and 3,4-dinitroglyoxime (nitration product) oxidative cyclization. Calculation results indicate that the electrophilic substitution of nitronium ions from the protonated HNO3 and the abstraction of hydrogen ions by HNO3 molecules are requisites of glyoxime nitration. The formation of a furoxan ring from 3,4-dinitroglyoxime involves two possible mechanisms: 1) oxydehydrogenation by NO2 molecules and the subsequent torsion of NO radical groups to form a ring and 2) the alternation of dehydrogenation and cyclization. The intermediates and transition states in both routes exhibit monoradical and diradical characteristics. Singlet and triplet reactions are considered for the diradical species. Results show that the singlet reaction mechanism is more favorable for cyclization than the triplet reaction. The formation of a furoxan ring from oxime is in accordance with the stepwise intermolecular dehydrogenation and intramolecular torsion to the ring.

10.
Phys Chem Chem Phys ; 17(10): 6995-7001, 2015 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-25684688

RESUMO

The structure and dynamics of the nitromethane-water (NM-WT) binary mixture surrounding single walled carbon nanotubes (SWNTs) have been investigated by molecular dynamics simulations. The simulation trajectories show that the NM molecules can be selectively adsorbed both outside the surface and inside the cavity of SWNTs mainly dominated by van der Waals attractions because SWNTs have a higher binding affinity for NM than WT. The binding energies of SWNTs with NM and WT obtained from electronic structure calculations at the M06-2X/6-31+G* level are 15.31 and 5.51 kcal mol(-1), respectively. Compared with the SWNT exterior, the selective adsorption of NM is preferentially occurred in the SWNT interior due to the hydrophobic interactions and the dipole-dipole interactions, which induces the decrease of the hydrogen-bond number of NM with WT and ordered structures of NM with preferred intermolecular orientation in the SWNT cavity. Furthermore, the selective adsorption dynamics of NM from the aqueous solution is regardless of the chirality and radius of SWNTs. The SWNT radius plays a negligible role in the mass density distributions of NM outside the SWNTs, while the mass density of NM in the SWNT interior decreases gradually as the SWNT radius increases. The structural arrangements and intermolecular orientations of NM in the SWNT cavity are greatly dependent on the SWNT radius due to the size effect.

11.
J Mol Model ; 21(3): 40, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25672840

RESUMO

The structural characteristics involving thermal stabilities of liquid nitromethane (NM)­one of the simplest energetic materials­confined within a graphene (GRA) bilayer were investigated by means of all-atom molecular dynamics simulations and density functional theory calculations. The results show that ordered and layered structures are formed at the confinement of the GRA bilayer induced by the van der Waals attractions of NM with GRA and the dipole-dipole interactions of NM, which is strongly dependent on the confinement size, i.e., the GRA bilayer distance. These unique intermolecular arrangements and preferred orientations of confined NM lead to higher stabilities than bulk NM revealed by bond dissociation energy calculations.

12.
J Mol Model ; 20(11): 2479, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25326063

RESUMO

In order to seek the potential high energy density compounds (HEDCs) with excellent performance and satisfactory safety, some combination rules are presented and 15 HEDCs are designed and sifted, and followed by the properties predicting. From the results, HEDC-3, HEDC-4, HEDC-9, HEDC-10, HEDC-11, HEDC-12, HEDC-13, and HEDC-14 have good comprehensive properties. They are furoxan, fused ring or cage-type compounds, whose frame is composed of some single ring by single (double or multi) point addition. Their densities are over 1.95 g cm(-3), and detonation velocities are over 9500 m s(-1). Their BDEs are over 85 kJ mol(-1), and the values of available free space (∆V) are lower than the ∆V of ß-CL20 (∆V = 86). In view of the synthesis feasibility, the synthesis routes of HEDC-4, HEDC-9, HEDC-10, HEDC-12, HEDC-13, and HEDC-14 have been designed.

13.
J Mol Model ; 20(10): 2459, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25231245

RESUMO

The stability of energetic materials confined in the carbon nanotubes can be improved at ambient pressure and room temperature, leading to potential energy storage and controlled energy release. However, the microscopic structure of confined energetic materials and the role played by the confinement size are still fragmentary. In this study, molecular dynamics simulations have been performed to explore the structural characteristics of liquid nitromethane (NM), one of the simplest energetic materials, confined in a series of armchair single-walled carbon nanotubes (SWNTs) changing from (5,5) to (16,16) at ambient conditions. The simulation results show that the size-dependent ordered structures of NM with preferred orientations are formed inside the tubular cavities driven by the van der Waals attractions between NM and SWNT together with the dipole-dipole interactions of NM, giving rise to a higher local mass density than that of bulk NM. The NM dipoles prefer to align parallel along the SWNT axis in an end-to-end fashion inside all the nanotubes except the (7,7) SWNT where a unique staggered orientation of NM dipoles perpendicular to the SWNT axis is observed. As the SWNT radius increases, the structural arrangements and dipole orientations of NM become disordered as a result of the weakening of van der Waals interactions between NM and SWNT.

14.
J Mol Model ; 20(7): 2343, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24980985

RESUMO

Although many 1,2,3,4-tetrazine-1,3-dioxide derivates have been synthesized, [1,2,5] oxadiazolo [3,4-e] [1,2,3,4]-tetrazine-4,6-di-N-dioxide (FTDO) is the only one with high enthalpy of formation and high detonation velocity. Whereas, its stability has not been studied. In the present work, the structure of FTDO was investigated using density functional theory (DFT) method, and its stability was calculated by potential energy surface scanning and structure interconvert thermodynamics under different temperatures. The spontaneous isomerization of FTDO and its effect on the stability of FTDO were investigated. The dissociation of FTDO to N2, N2O and furoxan fragments was studied, and the possibility of synthetic route from FTDO to TTTO was discussed.

15.
J Mol Model ; 17(5): 1017-27, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-20652342

RESUMO

Nitrosation reactions of malononitrile by three nitrosating agents, HONO, ClNO, and N(2)O(3), have been theoretically investigated at the B3LYP/cc-pVTZ and MP2/cc-pVDZ levels. Two possible competitive paths for nitrosation of malononitrile to give 2-nitroso-malononitrile were proposed: (a) direct C-nitrosation and (b) N-nitrosation and subsequent nitroso transfer from N to C atom. The calculations show that at both B3LYP and MP2 levels, path b is kinetically favored over path a for nitrosations by HONO and N(2)O(3). In the case of ClNO, the B3LYP predicts preference of path b, while the MP2 calculations suggest that both paths have similar rate-determining barriers. The data suggest that N(2)O(3) is the preferred nitrosating agent for the nitrosation of malononitrile in aqueous solution. Transformation of 2-nitroso-malononitrile to form malononitrileoxime via intramolecular proton transfer has also been explored, and it is found that inclusion of an assistant water molecule can drastically accelerate the tautomerization.


Assuntos
Nitrilos/química , Óxidos de Nitrogênio/química , Compostos Nitrosos/química , Ácido Nitroso/química , Prótons , Produtos Biológicos/química , Isomerismo , Modelos Químicos , Modelos Teóricos , Nitrosação , Teoria Quântica , Soluções , Termodinâmica , Água
16.
J Phys Chem B ; 115(1): 109-12, 2011 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-21155577

RESUMO

A monomolecular layer model of the surface phase of microdroplets was proposed, and the exact expression for Tolman length was derived in this paper. The Tolman lengths of water, n-pentane, and n-heptane were calculated by the expression, and the values are quite in agreement with the experimental values. By use of the Gibbs-Tolman-Kening-Buff equation, the exact relationship between the microdroplet surface tension and the radius is obtained, and the predicted values agree well with the simulated values. The results show that there is an obvious effect of the size of microdroplets (or nanoparticles) on the surface tension, and the surface tension decreases with decreasing droplet size. For the microdroplets of general liquid, only if their radius approaches or reaches 10(-9) m does the effect become significant.

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