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Tibetan medicine is one of the important components of our national medicine. In recent years, research on Tibetan medicine has gradually deepened from quality control, formulation research, chemical composition, and pharmacological effects. In addition, clinical application and experimental research have made great progress. This paper summarizes the latest developments in Tibetan medicine theory and experimental research, in order to provide reference for the development and clinical application of Tibetan medicine in the future.

In this article, we report a theoretical investigation on the role of several catalysts in the isomerisation mechanisms of HON(O)NNO2 to ON(OH)NNO2 by theoretical method of CBS-QB3. The isomerisation reactions with catalyst X (X = H2O, (H2O)2, HCOOH and H2SO4) are multi-hydrogen atom transfer reactions. Compared to the isomerisation mechanisms and rate constant of HON(O)NNO2 to ON(OH)NNO2 without catalysts, incorporation of the catalyst X shows different positive catalytic effects on affecting the reaction processes, with the H2SO4-assisted reaction being the most favourable. Such different catalytic effects are mainly related to the size of the ring structure in X-assisted transition states and the different values of pKa and proton affinities for HCOOH and H2SO4. Besides, compared with the barrier height of the isomerisation process from HON(O)NNO2 to ON(OH)NNO2 with HN(NO2)2 and HON(O)NNO2, the barrier of H2SO4-assisted reaction is lower by 9.3 and 4.5 kcal ·mol−1, meanwhile, the rate constant of H2SO4 catalyzed is larger than water and water dimer–assisted by 3–5 and 2–3 orders of magnitude, respectively. So, H2SO4-assisted reaction is the most favourable.

In this paper, two calcined Zhejiang diatomite and Jilin diatomite were modified by organic amine, polyethylene glycol, organocationic ions, organofunction group and metallic ions to adsorption and immobilize enzyme, the different organo-function group and metallic ions lead to the capacity of adsorptive enzyme changing with the variation of IEP value.

The stress state of coal surrounding a coalbed methane (CBM) production well is affected by the bottom hole flowing pressure (BHFP). The permeability of coal shows a marked change under compression. The BHFP must be restricted to a specific range to favor higher permeability in the surrounding coal and thus higher productivity of the well. A new method to determine this specific range is proposed in this paper. Coal has a rather low tensile strength, which induces tensile failure and rock disintegration. The deformation of coal samples under compression has four main stages: compaction, elastic deformation, strain hardening, and strain softening. Permeability is optimal when the coal samples are in the strain softening stage. The three critical values of BHFP, namely, p wmin, p wmid, and p wupper, which correspond to the occurrence of tensile failure, the start of strain softening, and the beginning of plastic deformation, respectively, are derived from theoretical principles. The permeability of coal is in an optimal state when the BHFP is between p wmin and p wmid. The BHFP should be confined to this specific range for the efficient drainage of CBM wells. This method was applied to field operations in three wells in the Hancheng CBM field in China. A comprehensive analysis of drainage data and of the BHFP indicates that the new method is effective and offers significant improvement to current practices.

According to salt rock creep test data and strain variation regulation of a salt mine, salt rock creep parameters are obtained based on Burgers creep model fitting. Statistical study of the probability distribution of the salt rock Burgers model creep parameters is carried out by K-S, A-D and C-M test method, from which probability model for each creep parameters is obtained. To achieve the purpose of determining the optimal probability model for each creep parameters, considering the acceptable level of various test method to different hypothesis probability model, the author put forward the comprehensive optimal acceptance criteria on the basis of limited comparison method, the correctness of which is proved by test result.

The effects of loading rate on splitting test, uniaxial compression strength, strength parameters in triaixal compression test, and creep failure of Hangcheng coal rock were investigated through indoor mechanical experiments. Experimental results shown that tensile strength, uniaxial strength and Youngs modulus of coal rock increased with the increase of loading rate and the increment is very small. Triaixal compression strength and loading rate has a linear relation. Brittleness was very marked under high loading rate. Ductility of coal rock in the steady creep stage diminished with the increase of loading rate, and failure mode of coal rock had a change from low ductility failure mode to ductile-to-brittle failure mode. The results of experimental researches can be used to determine the bottom hole flowing pressure of coalbed methane well.

The buried pipeline will be spanning and subject to dynamic load under flooding, which may induce a damage failure of pipeline. In this paper, a mechanical analysis model of spanning pipelines is established under different levels of flood load. The mechanical response and the information entropy based on strain energy of the pipeline are calculated through global analytical searching method. In addition, the recognition of damage failure of pipeline is achieved according to the value of strain energy entropy of pipeline under different flood levels. The study shows that the strain energy entropy varies with the change of deformation reflects the damage failure feature of pipeline well, which can be used as a new method to identify the failure of pipeline.

In order to determine the long-term mechanical properties of surrounding rock of salt cavern gas storage, long tri-axial creep test studies on rock salt of the field were carried out. Based on the test data, long-term strength of rock salt was determined, and comparatively analysis was conducted combined with of the instantaneous test. The study results show that: Considering the axial strain, radial strain and volumetric strain to determine the long-term strength of rock salt can ensure reliability of the results. Under the same condition, the less salt content, the value of long-term strength is higher. Tri-axial creep process has a different effect degree between cohesion and internal friction angle; it is more sensitive to cohesion. The strain limit should be considered for the stability analysis of multi-bedded salt cavern gas storage construction and pay more attention about the mechanical properties of the interlayer parts. The study results provide references for researching the surrounding rock long-term mechanical properties of salt cavern gas storage.

Three main fractures exist in coal rock mass, including face cleats, butt cleats, and major fractures. The distribution of cleats and beddings in coal rock mass likes a regular reticular. A geological model was established without considering the major fractures. Young's moduli of fractured coal rock mass were gained through a homogenization method monolayer composite micromechanics analysis method. The relations between volume fraction or Young's moduli of cleat and Young's moduli of coal rock mass were investigated by calculation. Results shown that Youngs moduli of coal rock mass have the same change trends with the increase of volume fraction of cleat in the interval of 0.0018mm of width of cleat. And the width of cleat of 0.5mm is a critical point. Youngs moduli of coal rock mass monotonically increase with the increase of Youngs modulus of cleat in the interval of 0.0010.008GPa. Volume fraction and Young's moduli of cleats have notable effects on Young's moduli of coal rock mass.

To build a stress-strain-time relationship of salt rock with unified instantaneous law and creep law, we combine the stress-strain curve with whole process of creep curve, looking for inner relation between softening curve and creep deformation. Finally, the stress-strain-time space surface is obtained. The researching results demonstrated that time and space development law of rock salts can be well reflected by it.

The stress and deformation of cut-off wall will be changed as the water level cyclical varying during reservoir's operation. Therefore, the prediction is important to the safety and stability of reservoir. In this paper, the seepage characteristics of the highest and the lowest water level condition have been predicted, and the variation of horizontal displacement is discussed under the vehicle load of road and cyclical fluid load. Meanwhile, the displacement distribution and stress state in junction area of the upper wall and the lower wall are obtained. The results show that the Cut-off wall is less affected by the vehicle load of road, and its stress and deformation will gradually stabilize after the second water store-discharge cycle. The upper reinforced concrete wall will tilt towards outside of reservoir, but the deformation is very small at lower plastic concrete wall. The guide wall has a good effect on preventing the upper wall's inclining and improving the lower wall's stress environment. Besides, the maximum principle stress of cut-off wall is too small to course plastic failure.

The geometry, energy, internal rotation barrier, dipole moments, and molecular polarizabilities of poly(vinylidene cyanide-tetracyanoethylene) (P(VDCN-TeCN)) of α- and β-chain models were studied with DFT at B3PW91/6-31G(d) level. The effects of chain length and TeCN content on the copolymer chain stabilities, chain conformations, and electric properties were examined and compared with those of the poly(vinylidene fluoride-tetrafluoroethylene) (P(VDF-TeFE)) copolymer and the polyvinylidene cyanide (PVDCN) homopolymer to explore whether P(VDCN-TeCN) possess an expected good piezoelectricity or not. Based on the internal rotation potential curves of P(VDCN-TeCN) dimer models (H[CH2C(CN)2–C(CN)2C(CN)2]H and H[C(CN)2CH2–C(CN)2C(CN)2]H), the conformational angles, relative stabilities of α- and β-conformations and the transition energy barriers of β→α and α→β were discussed. The results show that the stability of the β-conformation increases and the β→α transition in P(VDCN-TeCN) is more difficult than that in PVDCN. The energy difference per monomer unit between the β- and α-chains decreases with increasing TeCN content. The contribution of average dipole moment per monomer unit in the β-chain is affected by the chain curvature and TeCN content, and there is a weakly parabolic dependence on the VDCN content. For the same chain length, the calculations show that the dipole moment contribution per monomer unit in the P(VDCN-TeCN) with 0.5 molar fractions TeCN is smaller than either the β-chain PVDCN or the β-chain P(VDCN-TeFE). The chain length does not produce a significant change in the mean polarizability for either the α- or the β-P(VDCN-TeCN); however, the value increases with increasing the TeCN content in P(VDCN-TeCN)s.

The geometry, energy, internal rotation barrier, vibrational spectra, dipole moments and molecular polarizabilities of poly(vinylidene cyanide-trifluoroethylene) (P(VDCN-TrFE)) of α- and β-chain models were studied with density functional theory at B3PW91/6-31G(d) level. The effects of chain length and the trifluoroethylene (TrFE) content on the copolymer chain stabilities, chain conformations, electric properties and vibrational spectra were examined and compared with those of the poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer and the polyvinylidene cyanide (PVDCN) homopolymer to explore whether the ultrathin film of P(VDCN-TrFE) possess an expected good piezoelectricity or not. Based on the internal rotation potential curves of P(VDCN-TrFE) dimer models (H(CH 2 C(CN) 2 -CFHCF 2 )H and H(C(CN) 2 CH 2 -CF 2 CFH)H), the conformational angles, relative stabilities of α- and β-conformations and the transition energy barriers of β→α and α→β were discussed. The results show that the β-conformation is more stable than the α-conformation and the β→α transition in P(VDCN-TrFE) is more difficult than that in PVDCN. The energy difference per monomer unit between β- and α-chain P(VDCN-TrFE) copolymers with a variety of TrFE contents is smaller than that in PVDCN homopolymer, suggesting that α→β conformational change would be easier in the copolymer than in the homopolymer. The ideal β-chain of P(VDCN-TrFE) alternate copolymer with 50 mol% TrFE has a radius of about 16 A, which is almost twice as large as PVDCN (8.5 A) and the dipole moment contribution per monomer unit in the copolymer is even larger than the alternate P(VDF-TrFE) copolymer. The energy difference per monomer unit between the β- and α-chains decreases with increasing TrFE content. The contribution of average dipole moment per monomer unit in the β-chain is affected by the chain curvature and TrFE content, and there is a parabolic dependence on the VDCN content. The mean polarizability decreases with increasing TrFE content slightly. This work also predicted that there are some characteristic vibrational modes that may be used in identification of the α- and β-P(VDCN-TrFE) with different TrFE content.

Based on the results of triaxial compressive creep tests for five kinds of rock under the different stress loading, unloading and cycle-loading-unloading conditions, the creep deformation is not only a function of stress and time, but also it has the corresponding relations to the triaxial stress-strain curves of rock. The deformation properties of soften-strain, harden-strain and ideal plasticity presented by conventional triaxial compressive test curves under the different stress states were utilized, and the creep characteristics, the creep starting stress and the different entire creep process curves of rock were studied systematically according to creep experiment results, and the relations of the triaxial stress-strain curves to the creeping starting stress, the terminating curve, the different creep processes, and the different creep fracture properties were established. The relations presented in this paper were verified partially by the creep experiment results of five types of rock.

The structure, energy, internal rotation, dipole moments and molecular polarizabilities of poly(vinylidene cyanide) (PVDCN) of α- and β-chain models were studied with density functional theory at B3PW91/6-31G(d) level. The effects of chain length on the polymer chain stabilities, chain conformations and electric properties were examined and compared with those of the piezoelectric PVDF in order to explore the possible reasons that the piezoelectricity has not been observed in the bulk polymer of PVDCN experimentally. The results show that the energy barriers (11.5 and 6.9 kJ/mol) of PVDCN in its α- → β-chain and β- → α-chain transitions are smaller than those (16.3 and 8.2 kJ/mol) of PVDF, which promises an easier transition between the two conformations. This may be one of the reasons that the preparation of the stable piezoelectric phase will be difficult. However, an extremely important feature of the ideal β-chain is that the PVDCN chain is curved with a radius of only about 8.5 A, which is much smaller than that (30.0 A) in PVDF and is smaller than that (12.6 A) in polymethylvinylidenecyanide (PMVC). This suggests that the bulk polymer of PVDCN is difficult to be prepared into crystal phase, and the contribution of the dipole moment per unit to the total dipole will be cancelled if the chain is longer than 12 units (hemicycle). Therefore, the reasons that the piezoelectricity has not been found may be due to the orientation difficulties of chains and dipoles.

The internal rotation, geometry, energy, vibrational spectra, dipole moments and molecular mean polarizabilities of poly(vinylidene fluoride–tetrafluoroethylene) (P(VDF–TeFE)) of α- and β-chain models were studied with density functional theory at B3PW91/6-31G(d) level and compared with those of poly(vinylidene fluoride) homopolymer and P(VDF–TrFE) copolymer. The electric properties, chain conformation and stability of the copolymer influenced by the chain length and TeFE content were examined. Based on the internal rotation curves of P(VDF–TeFE) dimer models (H[CH2CF2–CF2CF2]H and H[CF2CH2–CF2CF2]H), the conformational angles, relative stabilities of α- and β-conformation, and the transition energy barriers of β → α and α → β were discussed. The results show that the β-conformation is more stable than the α-conformation thermodynamically and the β → α transition in P(VDF–TeFE) is more difficult than that in PVDF. Thus the copolymer should be in favor of preventing the piezoelectric phase from depolarization. The ideal β-chains are curved with a radius of about 30 A, which is very close to those in both PVDF and P(VDF–TrFE). Similar to P(VDF–TrFE), the α-chain P(VDF–TeFE) containing 0.50 mole fraction of TeFE is also a helical structure. However, the α-chain with 0.33–0.20 mole fraction of TeFE are almost linear in structure, which might be responsible for enhancing crystallinity of the copolymer. The contribution of average dipole moment per monomer unit in the β-chain is affected by the chain curvature and TeFE content, and there is a weakly parabolic dependence on the VDF content. The chain length and TeFE content will not significantly affect the mean polarizability per monomer unit. The calculations show that there are some characteristic vibrational modes that may be used in the identification of the α- and β-phase P(VDF–TeFE) with different TeFE contents.

B3PW91/6-31G density functional method was employed to investigate the elastic, strength and electronic properties of C 60 ( I h ) in its ground electronic state (X 1 A g ). Most of the properties were examined for larger structure distortions. The over-all elastic constant were derived from the near-equilibrium potential energy curves (PECs) in five independent directions [according to symmetries by 1. D 5d , 2. D 3d , 3. D 2h , 4. C 2h (1), 5. C 2h (2)]. By extension of the distortions as large as the structure of C 60 was destroyed, the necessary energies were obtained, which quantitatively illuminated the stability of C 60 theoretically. Analytical polynomial fit of the full PECs reproduced the energy data accurately. Time-dependent B3PW91/6-31G analysis showed significant electronic spectra changes associated with the structure distortions. Elongation in the direction of D 5d and compression in that of D 2h encountered potential energy surface cross-linkages, which might be considered as a single electron pump for further application in designs of single electron devices.

The geometry, energy, internal rotation, vibrational spectra, dipole moments and molecular polarizabilities of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) of α- and β-chain models were studied with density functional theory at B3PW91/6-31G(d) level and compared with those of the poly(vinylidene fluoride) (PVDF) homopolymer. The chain length and the trifluoroethylene (TrFE) concentration were examined to discuss the copolymer chain stabilities, chain conformations and electric properties. The asymmetrical internal-rotation potential energy curve shows that the angles for the g and g ′ conformations in the α-chain ( tg and tg ′) models are 53° and −70°, respectively, and the β-chain ( ttt ) conformation is a slightly distorted all-trans plane with dihedral angle at 177°. The energy differences, E β − E α( g ) and E β − E α( g ′) , between the β- and the α-conformation are 2.1 and 7.8 kJ/mol, respectively. These values are smaller than that in PVDF (8.4 kJ/mol), suggesting that the β-conformation in the copolymer will be more stable than in PVDF. The energy barriers for β → α( g ) and β → α( g ′) transitions are 16.2 and 5.8 kJ/mol, respectively. The former is almost twice of the energy barrier in PVDF by 8.2 kJ/mol and the latter is slightly smaller (by 2.4 kJ/mol) than that in PVDF. The respective energy barriers for α( g ) → β and α( g ′) → β transitions are 18.3 and 13.6 kJ/mol compared with the value 16.3 kJ/mol in PVDF. The asymmetrical energy barriers may be one of the reasons for the copolymers with 0.5–0.6 (mole fraction) VDF exhibiting complicated phase transition behavior. The conformation of α-chain P(VDF-TrFE) exhibits from a helical (containing higher TrFE) to a nearly beeline (containing lower TrFE). This behavior is different from that in the PVDF and the nearly beeline conformation might be responsible for the increasing crystallizability. The helical might also be associated with the complicated phase transition behavior and the larger lattice strain in the P(VDF-TrFE)s with higher TrFE concentration. The energy difference per monomer unit between the β- and α-chain decreases with increasing TrFE content. The ideal β-chain is curved with a radius of about 30 A, which is similar to that in PVDF. The chain curvature and the TrFE content will affect the dipole moment contribution per monomer. The chain length and TrFE content will not significantly affect the mean polarizability. The calculations indicated that there are some additional characteristic vibrational modes that may be used in identification of the α- or β-phase P(VDF-TrFE)s with different TrFE contents.

There are a large number of random distributing pores and cracks in rock mass, and the initial damages of different causes of formation may be grown with engineering action or changes of all kinds of natural conditions, and the physical and mechanical properties of rock are changed and the structure of rock mass is also changed. At the same time, not only the rock caverns located under groundwater table are subjected to the coupling action of stress field with seepage field, but also the deformation of surrounding rock varies with time. In order to consider these effects in the process of hydro-mechanical coupling, the rheological damage model of hydro-mechanical coupling was set up, based on the fundamental theories of rock mass hydraulics and rheological mechanics and damage mechanics. The according finite element analysis (FEA) formulas for rock mass were derived, and the concretely executive process was given for the FEA of coupled stress field with seepage field under the condition of considering rheological and damage for rock mass. The rheological damage model established may be applied to the long-term stability analysis for underground caverns and slope engineering under the condition of hydro-mechanical coupling.

Based on different surrounding rock classifications, the numerical simulation of visco-elasto-plastic surrounding rock was studied for three roadway tunnels with small spacing, especially analyzing the visco-elasto-plastic effect in the process of rock mass excavation by the step. By the numerical imitation and comparing analysis, the damage characteristic and the deformation law of surrounding rock were given under the same construction method for different surrounding rock classifications of three driveway tunnels, and the deformation law of interval wall and the relationship between the surrounding rock classification and the interval were obtained under the particular construction method for tunnels with small spacing. The minimum interval was selected for engineering design reference under the same excavation way, and a set of reasonable value ranges was given. The reference data and the theoretical basis were provided for the development and construction design of roadway tunnels with small spacing.

Density functional theory at B3PW91/6-31G level was employed to investigate the elastic, strength, vibrational spectra and electronic properties of He@C 60 ( I h ) in its ground electronic state (X 1 A g ) via structure distortions. The elastic properties were derived from the potential energy curves (PECs) in all of the five independent directions of the molecule with distorted symmetries by 1. D 5d , 2. D 3d , 3. D 2h , 4. C 2h (1) and 5. C 2h (2). PECs were examined towards where the structure of He@C 60 was destroyed and therefore the necessary energies were obtained, which illuminated the stability of He@C 60 . PECs are accurately fitted into polynomials. Elongations in the direction of D 5d and compression in D 2h encountered potential energy surface cross-linkages, which might be considered as a single electron pump for further application in design of single electron devices. Time-dependent B3PW91/6-31G analysis predicted significant electronic spectra changes associated with structure distortions. Properties have been compared with those in C 60 .

The internal rotation, geometry, energy, vibrational spectra, dipole moments and molecular polarizabilities of poly(vinylidene fluoride) (PVDF) of α- and β-chain models were studied by density functional theory at B3PW91/6-31G(d) level. The effects of chain lengths and monomer inversion defects on the electric properties and vibrational spectra were examined. The results show that the tgtg′ conformation angle between g and g′ is about 55° and the ttt conformation is a slightly distorted all-trans alternating planar zigzag with ±175° repeating motif. The average distance between adjacent monomer units in the β-PVDF is 2.567 A. The energy difference between the α- and β-chains is about 10 kJ/mol per monomer unit. The dipole moment will be affected by chain curvature (with a radius of about 30.0 A for ideal β-chain) and by defect concentration other than localization. The chain lengths and defects will not significantly affect the mean polarizability. The calculations indicated that there are some additional characteristic vibrational modes that may help identification of the α- and β-phase PVDF.

Domestic and foreign scholars have made untiring researches and brought out many research productions on the theoretical calculation method on surrounding rock pressure of tunnel. From the various yield criterion, stress-strain relationship and different modulus in tension and compression of rock and soil, it makes a discussion and evaluation about the present research status at home and abroad of the theoretical calculation method on surrounding rock pressure of circular tunnel under axisymmetric load. On this basis, it puts forward the development of theoretical calculation method on surrounding rock pressure of tunnel that the establishment of the surrounding rock pressure giving a comprehensive consideration of load condition, tunnel form, exist-null lining, yield criterion, modulus in tension and compression, material softening and shear dilatancy, et al.

Based on the engineering construction of new subway across existing metro tunnel, the settlement law of the existing metro concrete structures was researched due to construction perturbation under existing metro tunnel. According to the in-situ monitoring information and engineering geological conditions, the foundation model, structure analysis model and settlement curve model which are suitable for the main structure deformation have been respectively established, and the internal force and the stress law of the main structure were obtained through deformation analysis. The structure limit analysis model the maximum settlement, the maximum settlement difference value and the distributive characteristics of deformation and the internal force were determined in the whole construction period. The safety stability of the main structure and the normal operation of existing metro tunnel were evaluated, and the warning value was provided for the in-situ construction control.