Current technologies for analysis of biomass thermochemical processing: A review

Pyrolysis and gasification are two of the more promising utilization methods for the conversion of biomass toward a clean fuel source. To truly understand and model these processes requires detailed knowledge ranging from structural information of raw biomass, elemental composition, gas-phase reaction kinetics and mechanisms, and product distributions (both desired and undesired). The various analytical methods of biomass pyrolysis/gasification processing are discussed, including reactor types, analytical tools, and recent examples in the areas of (a) compositional analysis, (b) structural analysis, (c) reaction mechanisms, and (d) kinetic studies on biomass thermochemical processing.     

Dependence of the ordering degree and thermochemical characteristics of chitin and chitosan on their biological origin

Standard enthalpies of combustion and formation were studied, along with the enthalpy of interaction of chitin and chitosan of different origins with water. The concentration of the water phase solution in chitin and chitosan saturated at 273 K was determined by calorimetry from the enthalpy of melting of the water excess phase. The dependence of these properties on the source, molecular mass, and degree of ordering of polysaccharides was demonstrated.     

Session 1 Thermal,chemical, and biological processing

Applied Biochemistry and Biotechnology -     

Synthesis and thermochemical properties of NF2-containing energetic salts

Ammonium, 1,5-diamino-4-methyl-tetrazolium and 4-amino-1-methyl-triazolium salts of 5-difluoroaminodifluoromethyl-tetrazolate (TA-CF₂NF₂) were prepared by metathesis reactions of silver 5-difluoroaminodifluoromethyl-tetrazolate and the corresponding iodides. All are thermally stable to ∼150 °C. The ammonium salt has a density of 1.88 g cm⁻³. The combination of the CBS-4 method and isodesmic bond separation reactions was found to be an economical and reliable method to estimate heats of formation for polyfluorinated molecules. The standard heats of formation () of ammonium 5-difluoroaminodifluoromethyl-tetrazolate was calculated to be −53.13 kcal mol⁻¹ using the CBS-4 method. While its detonation pressures (P) and velocities (D) were estimated using Cheetah 4.0: P = 28.78 GPa; D = 8490 m s⁻¹; detonation properties for 1,5-diamino-4-methyl-tetrazolium salts of 5-difluoroaminomethyltetrazolate (TA-CH₂NF₂), 5-difluoroaminotetrazolate (TA-NF₂) and 5-difluoroaminodinitromethyl-tetrazolate (TA-C(NO₂)₂NF₂) are also compared based on predicted densities and computed heats of formation.     

Hybrid molecular probe for nucleic acid analysis in biological samples

The ability to detect changes in gene expression, especially in real-time and with sensitivity sufficient enough to monitor small variations in a single-cell, will have considerable value in biomedical research and applications. Out of the many available molecular probes for intracellular monitoring of nucleic acids, molecular beacon (MB) is the most frequently used probe with the advantages of high sensitivity and selectivity. However, any processes in which the MB stem-loop structure is broken will result in a restoration of the fluorescence in MB. This brings in a few possibilities for false positive signal such as nuclease degradation, protein binding, thermodynamic fluctuation, solution composition variations (such as pH, salt concentration) and sticky-end pairing. These unwanted processes do exist inside living cells, making nucleic acid monitoring inside living cells difficult. We have designed and synthesized a hybrid molecular probe (HMP) for intracellular nucleic acid monitoring to overcome these problems. HMP has two DNA probes, one labeled with a donor and the other an acceptor. The two DNA probes are linked by a poly(ethylene glycol) (PEG) linker, with each DNA being complementary to adjacent areas of a target sequence. Target binding event brings the donor and acceptor in proximity, resulting in quenching of the donor fluorescence and enhancement of the acceptor emission. The newly designed HMP has high sensitivity, selectivity, and fast hybridization kinetics. The probe is easy to design and synthesize. HMP does not generate any false positive signal upon digestion by nuclease, binding by proteins, forming complexes by sticky-end pairing, or by other molecular interaction processes. HMP is capable of selectively detecting nucleic acid targets from cellular samples.     

Double-hybrid functionals for thermochemical kinetics

We propose two new double-hybrid functionals, denoted B2K-PLYP and mPW2K-PLYP, which yield thermochemical performance comparable to existing double-hybrid functionals but offer superior performance for barrier heights of various kinds. We show that the new functionals yield excellent performance for all of the following: (a) main-group thermochemistry; (b) main-group thermochemical kinetics; (c) late transition metal reactions. In addition, B2K-PLYP performs well for weak interactions.     

Solution thermochemical assay of lanthanides

A method is proposed for the determination of binary mixtures of lanthanides in nitric acid using a non-aqueous thermometric system. If the atomic numbers of the lanthanides differ by 7 or more then the precision and reproducibility of the method are analytically acceptable.

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Zusammenfassung Es wird ein Verfahren unterbreitet, wie unter Anwendung nichtwäßriger thermometrischer Systeme die Zusammensetzung von binären Lanthanidengemischen in Salpetersäure ermittelt werden kann. Genauigkeit und Reproduzierbarkeit des Verfahrens sind analytisch annehmbar, wenn sich die Ordnungszahl der Lanthaniden um 7 oder mehr unterscheidet.

     

Experimental thermochemical study of two polymethylpyrazine N,N′-dioxide derivatives

The standard (p° = 0.1 MPa) molar enthalpies of formation of crystalline 2,3,5-trimethylpyrazine-1,4-dioxide and 2,3,5,6-tetramethylpyrazine-1,4-dioxide were measured, at T = 298.15 K, by static bomb calorimetry and the standard molar enthalpies of sublimation, at T = 298.15 K, were obtained from Calvet microcalorimetric measurements. These values were used to derive the respective standard molar enthalpies of formation in gaseous phase. The mean N–O bond dissociation enthalpy has been calculated for both compounds.     

Synthesis and thermochemical properties of dialkylfuroxans

Conclusions A number of dialkylfuroxans was synthesized and their thermochemical properties, namely the heats of combustion and the enthalpies of formation, were studied.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 842–846, April, 1973.     

A thermochemical analysis of inhalational anesthetics

The mechanism of the anesthetic process is of interest both to the clinician and to the pharmacologist. However, this is still an unsettled issue and a multitude of models have been proposed for the process. Noticing that most models propose either a molecular perturbation by the agents or an effect on some colligative property, we explore in this article the thermodynamical consequences of these postulations. Comparison of these with experimental findings is then made. The comparison shows the inconsistency of many of the models with the facts: (i) it refutes the long accepted conviction, culminated in the unitary hypothesis, that general anesthetics act not at a particular receptor site but invariably on all. Some consequences of this finding are demonstrated. (ii) it implies that a simple phospholipid medium is not feasible as an anesthetic site. (iii) it infers that proteins do have the properties required from anesthetic sites.Dedicated to Prof. Menachem Steinberg on the occasion of his 65th birthday     

Gas-phase thermochemical properties of pyrimidine nucleobases

The gas-phase acidity and proton affinity of thymine, cytosine, and 1-methyl cytosine have been examined using both theoretical (B3LYP/6-31+G*) and experimental (bracketing, Cooks kinetic) methods. This paper represents a comprehensive examination of multiple acidic sites of thymine and cytosine and of the acidity and proton affinity of thymine, cytosine, and 1-methyl cytosine. Thymine exists as the most stable "canonical" tautomer in the gas phase, with a DeltaH(acid) of 335 +/- 4 kcal mol(-1) (DeltaG(acid) = 328 +/- 4 kcal mol(-1)) for the more acidic N1-H. The acidity of the less acidic N3-H site has not, heretofore, been measured; we bracket a DeltaH(acid) value of 346 +/- 3 kcal mol(-1) (DeltaG(acid) = 339 +/- 3 kcal mol(-1)). The proton affinity (PA = DeltaH) of thymine is measured to be 211 +/- 3 kcal mol(-1) (GB = DeltaG = 203 +/- 3 kcal mol(-1)). Cytosine is known to have several stable tautomers in the gas phase in contrast to in solution, where the canonical tautomer predominates. Using bracketing methods in an FTMS, we measure a DeltaH(acid) for the more acidic site of 342 +/- 3 kcal mol(-1) (DeltaG(acid) = 335 +/- 3 kcal mol(-1)). The DeltaH(acid) of the less acidic site, previously unknown, is 352 +/- 4 kcal mol(-1) (345 +/- 4 kcal mol(-1)). The proton affinity is 228 +/- 3 kcal mol(-1) (GB = 220 +/- 3 kcal mol(-1)). Comparison of these values to calculations indicates that we most likely have a mixture of the canonical tautomer and two enol tautomers and possibly an imine tautomer under our conditions in the gas phase. We also measure the acidity and proton affinity of cytosine using the extended Cooks kinetic method. We form the proton-bound dimers via electrospray of an aqueous solution, which favors cytosine in the canonical form. The acidity of cytosine using this method is DeltaH(acid) = 343 +/- 3 kcal mol(-1), PA = 227 +/- 3 kcal mol(-1). We also examined 1-methyl cytosine, which has fewer accessible tautomers than cytosine. We measure a DeltaH(acid) of 349 +/- 3 kcal mol(-1) (DeltaG(acid) = 342 +/- 3 kcal mol(-1)) and a PA of 230 +/- 3 kcal mol(-1) (GB = 223 +/- 3 kcal mol(-1)). Our ultimate goal is to understand the intrinsic reactivity of nucleobases; gas-phase acidic and basic properties are of interest for chemical reasons and also possibly for biological purposes because biological media can be quite nonpolar.     

铁酸镍用于热化学循环反应CO2分解制CO的研究

采用共沉淀法制备了NiFe₂O₄和NiFe₂O₄/ZrO₂催化剂,用TGA考察了其热化学法,CO₂高温分解反应性能。通过对反应前后催化剂的表征发现,反应高温使两种催化剂都发生了明显的烧结,导致在热还原反应中形成的还原态氧化物不能完全被CO₂氧化从而降低了催化剂的反应性能;ZrO₂的加入对于提高催化剂的热稳定性以及循环反应稳定性具有重要的作用。在高温反应炉中考察了NiFe₂O₄/ZrO₂的CO₂分解实验,结果表明,提高热还原温度可以提高CO产量,然而,随着循环次数的增加CO的产量降低得更明显。     

Crystalline polysilicate magadiite with intercalated n-alkylmonoamine and some correlations involving thermochemical data

Synthesized hydrated lamellar acidic crystalline magadiite (H₂Si₁₄O₂₉·2H₂O) nanocompound was used as host for intercalation of polar n-alkylmonoamine molecules of the general formula H₃C(CH₂)_nNH₂ (n = 1–6) in aqueous solution. The original interlayer distance (d) of 1500 pm, determined by X-ray powder diffraction patterns, increases after intercalation. The values correlated with the number of aliphatic amine carbon (n_c) atoms: d = [(1312 ± 11) + (21 ± 2)]n_c. The amount of intercalated amines (N_s), decreased as n_c increased: N_s = [(5.82 ± 0.04) − (0.45 ± 0.01)]n_c. The acidic layered nanocompound was calorimetrically titrated with the amines and the thermodynamic data gave exothermic values for all guest molecules, as shown by the correlation: Δ_intH = −[(24.45 ± 0.49) − (1.91 ± 0.10)]n_c and d = [(1576 ± 16) − (10.8 ± 1.0)]Δ_intH. The negative values of the Gibbs energies and the positive entropies also presented the correlations: Δ_intG = −[(22.8 ± 0.2) − (0.2 ± 0.1)]n_c and Δ_intS = [(6 ± 1) + (5 ± 1)]n_c, respectively.     

Natural lycopene from Blakeslea trispora: all-trans lycopene thermochemical and structural properties

Structural and thermal properties of all-trans lycopene are described in the present paper. Different crystalline lycopene samples obtained from fermentation process and recrystallized lycopene were analyzed. Structural properties (NMR, mass spectrometry and powder X-ray diffraction) of lycopene were clarified with recent techniques. High purity sample analysis by differential scanning calorimetry was used to study thermal behavior of pure lycopene and with traces of isomers. But also this was correlated with HPLC method for determine lycopene purity and isomers in low proportion.     

CCBF--A system for the computer processing of chemical and biological facts

A computer-based system for the documentation of company research results in drug research is described. The system stores the numerous results of standardized biological tests and processes chemical formulas by topological techniques. The stored material is processed to provide computer-printed card indexes and lists on chemical and/or biological topics. The programs enable searches to be made for any desired substructure and for pharmacophoric groups, thus providing highly effective assistance in the search for structure-activity relationships.     

狼尾草特性及狼尾草/PP复合材料性能研究

对狼尾草茎秆进行拉伸性能测试和长径比测量、并进行X射线衍射图谱、红外光谱和热重分析,分别以三种粒径(40目、60目、80目)狼尾草茎秆纤维为填充材料,以聚丙烯(PP)为基体材料,使用模压成型工艺制备三种不同粒径的狼尾草/PP复合材料。对制备的复合材料进行了接触角测量、吸水性能和力学性能测试,并用扫描电子显微镜(SEM)观察了复合材料拉伸断面微观结构。结果表明:狼尾草茎秆纤维素类型为I型,相对结晶度为44%;40目、60目和80目三种目数狼尾草/PP复合材料24h吸水厚度膨胀率分别为7.7%、4.2%和4.4%;其中40目狼尾草/PP复合材料有较好的结合界面和较好的力学性能,其拉伸强度、弯曲强度、弯曲模量和冲击强度分别为10.47MPa、15.98MPa、1.9GPa和3.7kJ/m²。由此得知,40目狼尾草/PP复合材料力学性能最好,但吸水性较强;60目狼尾草/PP复合材料具有较好的力学性能和一定的抗吸水性,综合性能最佳。     

A thermochemical test of nonbonded interaction potentials

The energy of the geometric isomerisation of butene-2 was calculated, using different sets of semi-empirical nonbonded interaction potentials. Of the potential functions studied, those suggested by the authors and used by Scheraga were quite successful in reproducing the experimental result.