Structural Transition of the 2‐Nitropropane Organic Compound at Low Temperature

Structural investigation of the crystallized 2‐nitropropane compound (C₃H₇NO₂) was performed by X‐ray powder diffraction at low temperature. A first crystalline phase, called phase α, is observed below 172 K. This form exhibits a triclinic symmetry with P‐1 space group (a=1.0313(3) nm, b=0.5873(2) nm, c=1.6146(4) nm, α=90.17(2)°, β=92.17(2)° and γ=90.09(2)°), and Z=8). At T_t=172 K, a structural transition is observed which brings to another phase, called phase β (above T_t). This one contains four molecules per unit cell and shows a Pc2₁n symmetry (a=1.0141(3) nm, b=0.5855(2) nm, and c=0.8319(4) nm). In addition to the doubling of the c‐axis, structural networks differ by the different conformations of NO₂ nitro groups and by the orientation of the propyl group in the unit cell. Both crystal structures can be described using infinite zigzag chains of C₃H₇NO₂ molecules showing a regular alternation along the c‐axis. Two orientations of these ribbons, called A and B, are observed. The crystal structures are then built with different distribution of these ribbons within the crystalline network.     

Synthesis and Characterization of 3,4,5‐Triamino‐1,2,4‐Triazolium 5‐Nitrotetrazolate

3,4,5‐Triamino‐1,2,4‐triazolium 5‐nitrotetrazolate ( 2 ) was synthesized in high yield from 3,4,5‐triamino‐1,2,4‐triazole (guanazine) ( 1 ) and ammonium 5‐nitrotetrazolate. The new compound 2 was characterized by vibrational (IR and Raman) and multinuclear NMR spectroscopy (¹H, ¹³C, ¹⁵N), elemental analysis and single crystal X‐ray diffraction (triclinic, P(‐1), a=0.7194(5), b=0.8215(5), c=0.8668(5) nm, α=75.307(5), β=70.054(5), γ=68.104(5)°, V=0.4421(5) nm³, Z=2, ϱ=1.722 g cm⁻¹, R₁=0.0519 [F>4σ(F)], wR₂(all data)=0.1154). The ¹⁵N NMR spectrum and X‐ray crystal structure (triclinic, P‐1, a=0.5578(5), b=0.6166(5), c=0.7395(5) nm, α=114.485(5)°, β=90.810(5)°, γ=97.846(5)°, V=0.2286(3) nm³, Z=2, ϱ=1.658 g cm⁻¹, R₁=0.0460 [F>4σ(F)], wR₂(all data)=0.1153) of 1 were also determined.     

Synthesis,Crystal Structure,and Thermal Behavior of 3‐(4‐Aminofurazan‐3‐yl)‐4‐(4‐nitrofurazan‐3‐yl)furazan (ANTF)

The energetic material 3‐(4‐aminofurazan‐3‐yl)‐4‐(4‐nitrofurazan‐3‐yl)furazan (ANTF) with low melting‐point was synthesized by means of an improved oxidation reaction from 3,4‐bis(4′‐aminofurazano‐3′‐yl)furazan. The structure of ANTF was confirmed by ¹³C NMR spectroscopy, mass spectrometry, and the crystal structure was determined by X‐ray diffraction. ANTF crystallized in monoclinic system P2₁/c, with a crystal density of 1.785 g cm⁻³ and crystal parameters a=6.6226(9) Å, b=26.294(2) Å, c=6.5394(8) Å, β=119.545(17)°, V=0.9907(2) nm³, Z=4, μ=0.157 mm⁻¹, F(000)=536. The thermal stability and non‐isothermal kinetics of ANTF were studied by differential scanning calorimetry (DSC) with heating rates of 2.5, 5, 10, and 20 K min⁻¹. The apparent activation energy (E_a) of ANTF calculated by Kissinger's equation and Ozawa's equation were 115.9 kJ mol⁻¹ and 112.6 kJ mol⁻¹, respectively, with the pre‐exponential factor lnA=21.7 s⁻¹. ANTF is a potential candidate for the melt‐cast explosive with good thermal stability and detonation performance.     

Synthesis,Crystal Structure,and Thermal Behaviors of 3‐Nitro‐1,5‐bis(4,4′‐dimethylazide)‐1,2,3‐triazolyl‐3‐azapentane (NDTAP)

The energetic material, 3‐nitro‐1,5‐bis(4,4′‐dimethyl azide)‐1,2,3‐triazolyl‐3‐azapentane (NDTAP), was firstly synthesized by means of Click Chemistry using 1,5‐diazido‐3‐nitrazapentane as main material. The structure of NDTAP was confirmed by IR, ¹H NMR, and ¹³C NMR spectroscopy; mass spectrometry, and elemental analysis. The crystal structure of NDTAP was determined by X‐ray diffraction. It belongs to monoclinic system, space group C2/c with crystal parameters a=1.7285(8) nm, b=0.6061(3) nm, c=1.6712(8) nm, β=104.846(8)°, V=1.6924(13) nm³, Z=8, μ=0.109 mm⁻¹, F(000)=752, and D_c=1.422 g cm⁻³. The thermal behavior and non‐isothermal decomposition kinetics of NDTAP were studied with DSC and TG‐DTG methods. The self‐accelerating decomposition temperature and critical temperature of thermal explosion are 195.5 and 208.2 °C, respectively. NDTAP presents good thermal stability and is insensitive.     

Synthesis and Characterization of a New Class of Energetic Compounds – Ammonium Nitriminotetrazolates

1‐Methyl‐5‐nitriminotetrazole ( 1 ) and 2‐methyl‐5‐nitraminotetrazole ( 2 ) obtained by nitration of 1‐methyl‐5‐aminotetrazole ( 3 ) and 2‐methyl‐5‐aminotetrazole ( 4 ) were deprotonated using aqueous ammonia solution yielding the energetic compounds, ammonium 1‐methyl‐5‐nitriminotetrazolate ( 5 ) and ammonium 2‐methyl‐5‐nitriminotetrazolate ( 6 ). The nitrogen‐rich salts were tested and characterized comprehensively using vibrational spectroscopy (Infrared (IR) and Raman), multinuclear (¹H, ¹³C, ¹⁴N, and ¹⁵N) NMR spectroscopy, and elemental analysis. The molecular structures in the crystalline state were determined using low temperature single crystal X‐ray diffraction. The thermal behavior and the decompositions were investigated using differential scanning calorimetry (DSC) and gas IR spectroscopy. The heats of formation were calculated using bomb calorimetric measurements. In addition, the relevant detonation parameters, like the detonation pressure and velocity of detonation were calculated using the software EXPLO5 outperforming the values of TNT. Last but not least the sensitivities were determined using BAM methods showing moderate values against impact and friction (drophammer and friction tester) and the long‐term stabilities were tested using Flexy Thermal safety calorimetry (TSC). X‐ray crystallography: 5 : monoclinic, P2₁/c, a=370.06(2) pm, b=2079.06(9) pm, c=859.69(5) pm, β=99.120(5)°, V=65306(6) pm³, Z=4, ρ_calc=1.639 g cm⁻³; 6 : monoclinic, P2₁, a=365.39(2) pm, b= 788.82(5) pm, c=1124.95(7) pm, β=91.818(6), V=32408(3) pm³, Z=2, ρ_calc=1.651 g cm⁻³.     

Synthesis and Characterization of 1,4‐Dimethyl‐5‐Aminotetrazolium 5‐Nitrotetrazolate

1,4‐Dimethyl‐5‐aminotetrazolium 5‐nitrotetrazolate ( 2 ) was synthesized in high yield from 1,4‐dimethyl‐5‐aminotetrazolium iodide ( 1 ) and silver 5‐nitrotetrazolate. Both new compounds ( 1, 2 ) were characterized using vibrational (IR and Raman) and multinuclear NMR spectroscopy (¹H, ¹³C, ¹⁴N, ¹⁵N), elemental analysis and single crystal X‐ray diffraction. 1,4‐Dimethyl‐5‐aminotetrazolium 5‐nitrotetrazolate ( 2 ) represents the first example of an energetic material which contains both a tetrazole based cation and anion. Compound 2 is hydrolytically stable with a high melting point of 190 °C (decomposition). The impact sensitivity of compound 2 is very low (30 J), it is not sensitive towards friction (>360 N). The molecular structure of 1,4‐dimethyl‐5‐aminotetrazolium iodide ( 1 ) in the crystalline state was determined by X‐ray crystallography: orthorhombic, F_ddd, a=1.3718(1) nm, b=1.4486(1) nm, c=1.6281(1) nm, V=3.2354(5) nm³, Z=16, ρ=1.979 g cm⁻¹, R₁=0.0169 (F>4σ(F)), wR₂ (all data)=0.0352.     

Isothermal crystallization of metallocene‐based propylene/α‐olefin copolymers

Isothermal crystallization and subsequent melting behavior of two propylene/hexene‐1 copolymers and two propylene/octene‐1 copolymers prepared with metallocene catalyst were investigated. It is found that γ‐modification is predominant in all copolymers. The Avrami exponent shows a weak dependency on comonomer content and comonomer type. At higher crystallization temperatures (T_c) the crystallization rate constant changes more rapidly with T_c and the crystallization half‐time substantially increases. Double melting peaks were also observed at high T_c, which is attributed to the inhomogeneous distribution of comonomer units along the polymer chains and the existence of crystals with different lamellar thicknesses. The equilibrium melting temperatures (T) of the copolymers were obtained by Hoffman–Weeks extrapolation. It was found that the T decreases with increasing comonomer content, but are independent of comonomer type, implying that comonomer units are excluded from the crystal lattice. Dilation of the crystal lattice was also observed, which depends on crystallization, comonomer content, and comonomer type. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 240–247, 2005     

Study on Crystal Structure and Thermal Decomposition Mechanism of a Novel Coordination Compound [Zn(DAT)2(H2O)4](PA)2⋅2H2O

A novel coordination compound [Zn(DAT)₂(H₂O)₄](PA)₂⋅2H₂O has been synthesized using 1,5‐diaminotetrazole (DAT) as ligands. It crystallizes in the monoclinic space group C2/c, with a=1.51973(19) nm, b=0.67904(9) nm, c=3.0712(4) nm, β=90.507(2)°, V=3.1692(7) nm³, Z=4, and μ=0.888 mm⁻¹. With the intermolecular hydrogen bonds, molecules are linked together to form a three‐dimensional net structure. Thermal decomposition mechanism of the title compound was predicted based on DSC, TG‐DTG, and FT‐IR analyses. The kinetic parameters of the first exothermic process of the title compound were studied applying the Kissinger's and Ozawa–Doyle's methods.     

High‐Temperature Structural Transformations of 1,1‐Diamino‐2,2‐dinitroethene (FOX‐7)

Stuctural transformations of 1,1‐diamino‐2,2‐dinitroethene (FOX‐7) were investigated in the temperature range 298–513 K by means of DSC, TG, isothermal calorimetry, PXRD, IR spectroscopy, and electron microscopy. The data obtained confirm the existence of the high‐temperature δ‐FOX‐7 polymorph stable above 480 K. The heat effect of the γ→δ transformation is − 4.6 J g⁻¹ (−680 J mol⁻¹). Metastable γ‐phase formed in the reverse process δ→γ has a perfect crystal structure and is stable towards thermal decomposition. Possible mechanisms of sharp deceleration of thermal decomposition of FOX‐7 at the 40 % conversion are discussed.     

Thermal analysis of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) irradiated under vacuum

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) was irradiated by ⁶⁰Co γ‐rays (doses of 50, 100 and 200 kGy) under vacuum. The thermal analysis of control and irradiated PHBV, under vacuum was carried out by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The tensile properties of control and irradiated PHBV were examined by using an Instron tensile testing machine. In the thermal degradation of control and irradiated PHBV, a one‐step weight loss was observed. The derivative thermogravimetric curves of control and irradiated PHBV confirmed only one weight‐loss step change. The onset degradation temperature (T_o) and the temperature of maximum weight‐loss rate (T_p) of control and irradiated PHBV were in line with the heating rate (°C min^?1). T_o and T_P of PHBV decreased with increasing radiation dose at the same heating rate. The DSC results showed that ⁶⁰Co γ‐radiation significantly affected the thermal properties of PHBV. With increasing radiation dose, the melting temperature (T_m) of PHBV shifted to a lower value, due to the decrease in crystal size. The tensile strength and fracture strain of the irradiated PHBV decreased, hence indicating an increased brittleness. Copyright © 2004 Society of Chemical Industry     

Preparation and Molecular Structure of {[Ca(CHZ)2(H2O)](NTO)2⋅3.5H2O}n

The title compound {[Ca(CHZ)₂(H₂O)](NTO)₂⋅3.5H₂O}_n was synthesized by using an aqueous solution of calcium 3‐nitro‐1,2,4‐triazol‐5‐onate and carbohydrazide (CHZ, NH₂NHCONHNH₂). Its molecular structure was determined by X‐ray diffraction and its crystals have monoclinic form, with space group C2/c, where a=2.4483(4) nm, b=1.2581(2) nm, c =1.6269(3) nm, β=121.168(12)°, V=4.2879(13) nm³, Z=8, d_c=1.727 g⋅cm⁻³, μ (Mo K_α)=3.9 cm⁻¹, M=557.47, F(000)=2312. The coordination polyhedron is a tricapped trigonal prism in a tetradecahedron with a coordination number of nine. The whole molecule has many long chains formed through the carbohydrazide bridges, and every long chain is unlimited along the c axis. The long chains are linked by hydrogen bonds to form the crystal structure.     

Synthesis and characterization of temperature‐sensitive block copolymers from poly(N‐isopropylacrylamide) and 4‐methyl‐ε‐caprolactone or 4‐phenyl‐ε‐caprolactone

This study synthesizes thermally sensitive block copolymers poly(N‐isopropylacrylamide)‐b‐poly(4‐methyl‐ε‐caprolactone) (PNIPA‐b‐PMCL) and poly(N‐isopropylacrylamide)‐b‐poly(4‐phenyl‐ε‐caprolactone) (PNIPA‐b‐PBCL) by ring‐opening polymerization of 4‐methyl‐ε‐caprolactone (MCL) or 4‐phenyl‐ε‐caprolactone (BCL) initiated from hydroxy‐terminated poly(N‐isopropylacrylamide) (PNIPA) as the macroinitiator in the presence of SnOct₂ as the catalyst. This research prepares a PNIPA bearing a single terminal hydroxyl group by telomerization using 2‐hydroxyethanethiol (ME) as a chain‐transfer agent. These copolymers are characterized by differential scanning calorimetry (DSC), ¹H‐NMR, FTIR, and gel permeation chromatography (GPC). The thermal properties (T_g) of diblock copolymers depend on polymer compositions. Incorporating larger amount of MCL or BCL into the macromolecular backbone decreases T_g. Their solutions show transparent below a lower critical solution temperature (LCST) and opaque above the LCST. LCST values for the PNIPA‐b‐PMCL aqueous solution were observed to shift to lower temperature than that for PNIPA homopolymers. This work investigates their micellar characteristics in the aqueous phase by fluorescence spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering (DLS). The block copolymers formed micelles in the aqueous phase with critical micelle concentrations (CMCs) in the range of 0.29–2.74 mg L^?1, depending on polymer compositions, which dramatically affect micelle shape. Drug entrapment efficiency and drug loading content of micelles depend on block polymer compositions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Improved thermal stability of the piezoelectric properties of (Li,Ag)‐co‐modified (K,Na) NbO3‐based ceramics prepared by spark plasma sintering

High‐performance lead‐free piezoelectric ceramics 0.94(K_0.45Na_0.55)_1?xLi_x(Nb_0.85Ta_0.15)O₃–0.06AgNbO₃ (KNNLTAg‐x) were successfully prepared by spark plasma sintering technique. The doping effect of Li on the structural and electrical properties of KNNLTAg‐x (x=0, 0.02, 0.04, 0.06, 0.08 and 0.10) ceramics was studied. The lattice structure, ferroelectric and piezoelectric properties of the KNLNTAg‐x ceramics are highly dependent on the Li doping level. In particular, the Li dopant has a great impact on both Curie temperature T_c and orthorhombic‐tetragonal transition temperature T_O‐T. The 4% Li‐doped sample exhibited relatively high T_O‐T of 95°C, leading to a stable dynamic piezoelectric coefficient (d₃₃*) of 220‐240 pm/V in a broad temperature range from 25°C to 105°C. Additionally, the 2% Li‐doped sample shows a high d₃₃* of 320 pm/V at 135°C, suggesting its great potential for high‐temperature applications.     

Synthesis of star‐shaped poly(ε‐caprolactone)‐b‐poly(L‐lactide) copolymers: From star architectures to crystalline morphologies

Hexa‐armed star‐shaped poly(ε‐caprolactone)‐block‐poly(L ‐lactide) (6sPCL‐b‐PLLA) with dipentaerythritol core were synthesized by a two‐step ring‐opening polymerization. GPC and ¹H NMR data demonstrate that the polymerization courses are under control. The molecular weight of 6sPCLs and 6sPCL‐b‐PLLAs increases with increasing molar ratio of monomer to initiator, and the molecular weight distribution is in the range of 1.03–1.10. The investigation of the melting and crystallization demonstrated that the values of crystallization temperature (T_c), melting temperature (T_m), and the degree of crystallinity (X_c) of PLLA blocks are increased with the chain length increase of PLLA in the 6sPCL‐b‐PLLA copolymers. On the contrary, the crystallization of PCL blocks dominates when the chain length of PLLA is too short. According to the results of polarized optical micrographs, both the spherulitic growth rate (G) and the spherulitic morphology are affected by the macromolecular architecture and the length of the block chains. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Non‐Isothermal Decomposition Kinetics,Heat Capacity,and Thermal Safety of 2‐Nitroimino‐5‐Nitro‐Hexahydro‐1,3,5‐Triazine (NNHT)

The kinetic equation describing the thermal decomposition reaction of NNHT obtained by TG‐DTG data, integral isoconversional non‐linear method and integral method of treating TG‐DTG curves is . The specific heat capacity (C_p) of NNHT was determined with the continuous C_p mode of the microcalorimeter. The equation of C_p (T) was obtained. The standard molar heat capacity of NNHT was 218.41 J mol⁻¹ K⁻¹ at 298.15 K. With the help of the onset temperature (T_e) and maximum peak temperature (T_p) from the non‐isothermal DTG curves of NNHT at different heating rates (β), the apparent activation energy (E_K and E_O), and the pre‐exponential constant (A_K) of the thermal decomposition reaction obtained by Kissinger’s method and Ozawa’s method, C_p obtained by microcalorimetry, density (ρ) and thermal conductivity (λ), the decomposition heat (Q_d, taking half‐explosion heat), Zhang‐Hu‐Xie‐Li’s formula, Smith’s equation, Friedman’s formula, Bruckman‐Guillet’s formula, and Wang‐Du’s formulas, the values (T_e0 and T_p0) of T_e and T_p corresponding to β→0, thermal explosion temperature (T_be and T_bp), adiabatic time‐to‐explosion (t_TIad), 50 % drop height (H₅₀) of impact sensitivity, critical temperature of hot‐spot initiation (T_cr), thermal sensitivity probability density function [S(T)] versus temperature (T) relation curves for spheroidic NNHT with radius of 1 m surrounded with ambient temperature of 300 K, peak temperature corresponding to the maximum value of S(T) versus T relation curve ( ), safety degree (SD), and critical ambient temperature(T_acr) of thermal explosion of NNHT are calculated. The following results of evaluating the thermal safety of NNHT are obtained: T_SADT=T_e0=453.34 K, T_SADT=T_p0=454.86 K, T_be=462.68 K, T_bp=467.22 K, t_TIad=1.03 s, H₅₀=17.69 cm, T_α=461.4 K. SD=72.74 %, P_TE=27.26 %, and T_acr=321.96 K.     

Thermogravimetric analysis of poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)

The thermal degradation of poly(3‐hydroxybutyrate) (PHB) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) [P(HB‐HV)] was studied using thermogravimetry (TG). In the thermal degradation of PHB, the temperature at the onset of weight loss (T_o) was derived by T_o = 0.97B + 259, where B represents the heating rate (°C/min). The temperature at which the weight loss rate was maximum (T_p) was T_p = 1.07B + 273, and the final temperature (T_f) at which degradation was completed was T_f = 1.10B + 280. The percentage of the weight loss at temperature T_p (C_p) was 69 ± 1% whereas the percentage of the weight loss at temperature T_f (C_f) was 96 ± 1%. In the thermal degradation of P(HB‐HV) (7:3), T_o = 0.98B + 262, T_p = 1.00B + 278, and T_f = 1.12B + 285. The values of C_p and C_f were 62 ± 7 and 93 ± 1%, respectively. The derivative thermogravimetric (DTG) curves of PHB confirmed only one weight loss step change because the polymer mainly consisted of the HB monomer only. The DTG curves of P(HB‐HV), however, suggested multiple weight loss step changes; this was probably due to the different evaporation rates of the two monomers. The incorporation of 10 and 30 mol % of the HV component into the polyester increased the various thermal temperatures (T_o, T_p, andT_f) by 7–12°C (measured at B = 20°C/min). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2237–2244, 2001     

Triazidotrinitro Benzene: 1,3,5‐(N3)3‐2,4,6‐(NO2)3C6

Triazidotrinitro benzene, 1,3,5‐(N₃)₃‐2,4,6‐(NO₂)₃C₆ ( 1 ) was synthesized by nitration of triazidodinitro benzene, 1,3,5‐(N₃)₃‐2,4‐(NO₂)₂C₆H with either a mixture of fuming nitric and concentrated sulfuric acid (HNO₃/H₂SO₄) or with N₂O₅. Crystals were obtained by the slow evaporation of an acetone/acetic acid mixture at room temperature over a period of 2 weeks and characterized by single crystal X‐ray diffraction: monoclinic, P 2₁/c (no. 14), a=0.54256(4), b=1.8552(1), c=1.2129(1) nm, β=94.91(1)°, V=1.2163(2) nm³, Z=4, ϱ=1.836 g⋅cm⁻³, R_all =0.069. Triazidotrinitro benzene has a remarkably high density (1.84 g⋅cm⁻³). The standard heat of formation of compound 1 was computed at B3LYP/6‐31G(d, p) level of theory to be ΔH°_f=765.8 kJ⋅mol⁻¹ which translates to 2278.0 kJ⋅kg⁻¹. The expected detonation properties of compound 1 were calculated using the semi‐empirical equations suggested by Kamlet and Jacobs: detonation pressure, P=18.4 GPa and detonation velocity, D=8100 m⋅s⁻¹.     

Preparation,Crystal Structure,Thermal Decomposition,and Explosive Properties of [Cd(en)(N3)2]n

A new multi‐ligand coordination polymer of cadmium(II) ethylenediamine azide, [Cd(en)(N₃)₂]_n (en=ethylenediamine), was synthesized and characterized by using elemental analysis and FT‐IR spectrum. Its crystal structure was determined by means of X‐ray single crystal diffraction. The obtained results show that this crystal belongs to monoclinic, P2₁/n space group, a=0.6548(1) nm, b=1.0170(2) nm, c=1.2246(2) nm, β=90.23(1)°, V=0.8156(2) nm³, D_c=2.090 g⋅cm⁻³, Z=4, R₁=0.024, wR₂ (I>2σ(I))=0.0416 and S=0.998. The Cd(II) ion is six‐coordinated with four azido ligands by μ‐1, 1 azido bridges, and two ethylenediamine molecules which serve as bidentate ligands through the nitrogen atoms. The thermal decomposition mechanism of the title complex was studied by using differential scanning calorimetry (DSC) and thermogravimetry‐differential thermogravimetry (TG–DTG) techniques. Under nitrogen atmosphere with a heating rate of 10 K⋅min⁻¹, the thermal decomposition of the complex contains two main successive exothermic processes between 519 and 701 K in the DSC curve, and the final decomposed residue at 725 K is Cd. The non‐isothermal kinetics parameters were calculated by using the Kissinger's method, Ozawa–Doyle's method, pervasive integration method, and differential method, respectively. The sensitivity properties of [Cd(en)(N₃)₂]_n were also determined with standard methods.