Calorimetry Research Articles

The Potential Incorporation of Biochar into a Char-Water Fuel — Study of Chemical and Physical Properties

Biochar has the potential to be used for a wide range of applications. One of these includes utilisation as a char-water fuel, with the aim of substituting less sustainable fuels in the future. This paper reports the chemical and physical properties of biochar produced from sugarcane bagasse for use as a char-water fuel. Sugarcane bagasse was pre-treated with diammonium phosphate (DAP) and pyrolysed to increase the yield of biochar. An untreated sample of bagasse was also converted to biochar for comparison. The treated samples were formulated into char-water fuel and analysed for rheological behaviour. Viscosities were comparable to that reported for coal-water slurry fuels and, in some cases, other biological by-products (i.e. biooils), but were higher than diesel or gasoline. Thermal gravimetric analysis (TGA) and particle size distribution were conducted on the char samples and the energy content was measured using bomb calorimetry. The energy content of the char-water fuel would be similar to that of coal-water fuels if beneficiation of the biochar to remove ash components can be performed.

Kinetic Analysis of Melon Seed Husk Using Non-Isothermal Thermogravimetric Analysis

Melon seed husk (MSH) is cheap and renewable agricultural waste biomass residue with potential for future sustainable energy utilization. However lack of comprehensive data on the physicochemical and thermokinetic characteristics of MSH has hampered its potential valorization into clean bioenergy fuels. Consequently, the solid biofuel (SBF) properties of melon seed husks (MSH) were examined in this study under pyrolysis conditions. The SBF properties of MSH was investigated through elemental, proximate analysis and bomb calorimetry to determine the elemental and calorific properties of MSH. Thermal analysis was examined by TGA/DTG analysis to examine the decomposition behavior and devolatization profile of MSH. Subsequently, the decomposition kinetics was examined by the Kissinger and isoconversional Flynn-Wall-Ozawa (FWO) models to determine the activation energy Ea and frequency factor A. The results for the Kissinger method indicated Ea = 161.26 kJ/mol and frequency factor, A = 2.08 x 1010 min-1 with the correlation value, R2 = 0.9958. For FWO, the Ea for MSH ranged from 146.81 - 296 kJ/mol for α = 0.15 to 0.60 with average Ea and A values of 192.96 kJ/mol and 2.86 x 1026 min-1, respectively at R2 = 0.9847. Overall, the results highlight the potential of MSH as a cheap, renewable and sustainable SBF for future utilization in bioenergy systems.

Metabolic profile of children with extrahepatic portal vein obstruction undergoing meso-Rex bypass

BackgroundExtrahepatic portal vein obstruction (EHPVO) in children is often associated with growth restriction, which improves after the restoration of portal venous flow with a meso-Rex bypass, but the physiologic mechanism is unknown. The purpose of this study was to investigate the mechanism of growth delay in children with EHPVO by detailing the metabolic and nutritional profile before and after meso-Rex bypass. MethodsTwenty consecutive children with EHPVO were prospectively studied before and 1 year after meso-Rex bypass. Caloric balance was determined by investigating caloric intake via a calorie count, total energy expenditure via a doubly labeled water isotope assay and stool caloric loss by bomb calorimetry. Laboratory markers of nutrition and growth hormone resistance were tested. ResultsFifteen of the 20 children underwent successful meso-Rex bypass at a median age of 4.3 years. Prealbumin level was abnormally low (14.6 ± 3.0 mg/dL) at surgery but improved (17.0 ± 4.3 mg/dL) 1 year later (P = 0.026). Mean insulin-like growth factor 1 (IGF-1) level at baseline was 1.57 standard deviations below normal. IGF-1 levels increased from 88.3 ± 38.9 to 117.3 ± 54.5 ng/mL in the year after surgery (P = 0.047). Caloric intake divided by basal metabolic rate (1.90 ± 0.61), total energy expenditure (97.2 ± 15.0% of expected), and stool caloric losses (3.7 ± 1.8% of caloric intake) were all normal at baseline. ConclusionsChildren with EHPVO suffer from malnutrition and growth hormone resistance, which may explain their well-established finding of growth restriction. Prealbumin and IGF-1 levels improve after a successful meso-Rex bypass.

PREPARATION AND EVALUATION OF IRBESARTAN-CYCLODEXTRIN INCLUSION COMPLEXES

In the present work effect of methyl-I²-cyclodextrin (MI²CD) on physical properties and dissolution rate of Irbesartan (IRB) was studied.Based on AL-type ofphase solubility diagram obtained, solid binary systems of the drug with MI²CD were prepared in 1:1 molar ratio by various methods. Complexes were characterized using Differential Scanning Calorimetry and powder X-Ray Diffractometry. It could be concluded that IRB can form inclusion complex with MI²CD. The dissolution profiles of inclusion complexes were compared with those of IRB alone and the physical mixture. The dissolution rate of IRB was increased remarkably by MI²CD inclusion complexation.

Synthesis of Two Lead Complexes of Propellant Stabilizer Compounds: In Pursuit of Novel Propellant Additives

AbstractTwo lead complexes, Tetrakis(μ3‐(4‐methyl‐3‐nitrophenyl imido lead (II))) 1, and Bis(2‐nitrodiphenyl amido lead(II)) 2, were prepared by protolysis of bis(bis(trimethylsilyl)amido)lead(II) with two compounds relevant to double‐base propellant stabilizers: 2‐nitrodiphenylamine (NDPA) and 4‐methyl‐3‐nitroaniline. Crystal structures were determined as tetrahydrofuran solvates, and exhibit a number of unusual geometric features, including low lead coordination number. Heats of combustion and formation were determined using bomb calorimetry and converted to energy density using crystallographic densities. Compound 1 has an energy density of 30 MJ/L, whereas 2 was 38.2 MJ/L.

Using thermal methods to understand the interactions between a rocket propellant and igniter material

A number of ageing studies have been performed in order to ascertain the effect that a boron potassium nitrate-containing composition known as SR44 has on a nitroglycerine (NG)-based rocket propellant. These have shown that SR44 causes significant stabiliser decomposition in the propellant and heat flow calorimetry (HFC) has demonstrated that the two materials are incompatible with each other. Previous research had concentrated on heating the two materials in close proximity, even if they were not in direct contact. In this latest study, the propellant has been aged as far apart from the SR44 as possible inside a three-litre Kilner jar. Further to this, the effect of adding a composite propellant to the vessel has also been assessed as this would also normally be found in an igniter. Ageing has been conducted in the presence of different concentrations of relative humidity in order to look at the effect of moisture on the decomposition reactions. A number of thermal techniques have been used to characterise the materials and to try and understand the interactions between them. These have included HFC, differential scanning calorimetry (DSC) and bomb calorimetry. The data illustrate that even when the propellant and igniter material are separated by a notable distance, the SR44 still has an adverse effect on the propellant in terms of stabiliser decomposition. However, the relationship between relative humidity and degradation reactions appears to be different in the propellant when SR44 is present compared with when it is absent. Whilst it is clear that SR44 adversely affects the propellant, it has been more difficult to unequivocally demonstrate the effect of the propellant on the igniter composition. As a result, a new method has been developed which may enable the quantification of potassium nitrate in SR44 to be improved as it has been demonstrated that the presence of boric acids can affect this measurement. Essentially this involves heating the SR44 in a DSC from 100 to 160 °C at 5 °C min−1 before cooling it back to 100 °C and repeating the test. By doing this, the boric acids are removed from the SR44 which allows a more accurate figure for the concentration of potassium nitrate to be obtained. HFC has previously illustrated that it is important to understand if boric acids are forming in the SR44 as these can react with NG even if the materials are not in direct contact (Tunnell et al. in: Proceedings of the 9th international heat flow calorimetry conference, Finland, September, 2015). In the most extreme case where boric oxide forms to a sufficient concentration, this can cause the NG to ignite. It is therefore important to subject any SR44 contained within an igniter which is in a NG-based rocket motor to regular analysis. This is in order to find out if any acidic degradation products are accumulating which can lead to an increase in stabiliser consumption and, ultimately, significant NG decomposition within the propellant.

High-temperature crystallographic and thermodynamic investigations on synthetic zirconolite (CaZrTi2O7)

In this paper, we report the crystal structure and thermodynamic parameters of zirconolite (CaZrTi2O7) which is a potential ceramic matrix for incorporation of nuclear high-level waste. The room temperature structural studies revealed a two layer monoclinic (C2/c) structure for the compound. Thermal expansion behavior of zirconolite was investigated by the high-temperature XRD. The average thermal expansion coefficient of zirconolite, measured in the temperature range 298–1273 K, is found to be: a-axis (A) = 12.410(2) + 1.06(8) × 10−4 [T] + 3.1(5) × 10−8 [T]2/K, b-axis (A) = 7.252(1) + 6.2(4) × 10−5 [T] + 4.9(2.5) × 10−9 [T]2/K and c-axis (A) = 11.351(2) + 7.6(7) × 10−5 [T] + 3.2(4) × 10−8 [T]2/K. The standard molar enthalpy of formation of zirconolite (CaZrTi2O7, s) at 298.15 K determined employing high-temperature solution calorimetry is found to be − 3716.5 ± 3.7 kJ mol−1. The isobaric heat capacity of the CaZrTi2O7(s) has been derived from the enthalpy increment (H T–H 298.15) data. Based on the experimental data for the compound and the available thermodynamic data for the component oxides, thermodynamic functions like: $${\text{Cp}}_{\text{m}}^{\circ } ,S_{\text{m}}^{\circ } , H_{{{\text{m}},{\text{T}}}}^{0} , { }G_{\text{m,T}}^{\circ } , \left( {H_{\text{T}}^{\circ } - H_{298.15}^{\circ } } \right), - \left( {\frac{{G_{\text{T}}^{\circ } - H_{298.15}^{\circ } }}{T}} \right), \Delta_{\text{f}} H_{{{\text{m}},298.15}}^{\circ } \,\, {\text{and}}\,\,\Delta_{\text{f}} G_{{{\text{m}},{\text{T}}}}^{\circ }$$ for zirconolite (CaZrTi2O7, s) have been generated.

Analysis of thermal behavior and pyrolytic characteristics of vetiver grass after phytoremediation through thermogravimetric analysis

In this work, pyrolysis experiments of vetiver grass (Vetiveria zizanioides) after phytoremediation of arsenic, fluoride and manganese were carried out in a thermogravimetric analyzer under inert atmosphere at three heating rates of 5, 10 and 20 °C min−1 in order to investigate the thermal degradation behavior of vetiver grass. The physicochemical properties of vetiver grass were investigated by proximate and ultimate analysis, lignocellulosic composition, Bomb calorimetry and FTIR spectroscopy. The results showed that vetiver grass has high volatile matter content and high calorific value. Kinetic parameters for pyrolysis of vetiver grass were evaluated using three different kinetic models suggested by Kissinger–Akahira–Sunose (KAS), Ozawa–Flynn–Wall (OFW) and Coasts–Redfern using TGA data. The average activation energy values of vetiver grass calculated by using KAS and OFW models are found as 151.23 and 161.33 kJ mol−1, respectively. Coasts-Redfern model has been used to compute the pre-exponential factor. The physicochemical properties and kinetic parameters verify the suitability of vetiver grass as a potential feedstock for pyrolysis.

Characteristics of briquettes developed from rice and coffee husks for domestic cooking applications in Uganda

Abstract The goal of this study was to develop briquettes from coffee and rice husks agricultural wastes as sustainable fuel sources for domestic cooking applications. Clay and cassava starch were used as binders. Physical properties of the coffee husks and rice husks as well as the developed briquettes were determined using Thermogravimetric analysis. Higher heating value (HHV) results were determined using bomb calorimetry. Drop test method was used to determine the mechanical and storage integrity of the developed briquettes. The results showed that the type of binder used in the development of the briquettes significantly affected both their physical properties and calorific values. Average higher heating values for briquettes developed with cassava starch binder ranged from 21.9 to 23.0 MJ/kg for coffee husks and 15.9–16.6 MJ/kg for rice husks. For coffee and rice husk briquettes developed with clay binder, average higher heating values ranged from 13.0 to 19.5 MJ/kg and 9.5–13.8 MJ/kg, respectively. Generally, cassava starch binder imparted higher drop strengths (over 95%) onto the briquettes than clay binder material. The characteristics were influenced by the physical properties of the raw biomass material as well as the high SiO2 ash in the clay binder.

Energy Density and Dry Matter Content in Fish: New Observations and an Evaluation of Some Empirical Models

AbstractEnergy density (ED) is an indicator of fish nutritional status, physiological status, and fitness. Estimates of ED of predators and prey are also needed for bioenergetics modeling, but direct measurements of ED are difficult to obtain. Hence, investigators often borrow published values from the same species or related species. Alternatively, models have been developed that predict ED from dry matter content (DM). The scarcity of published ED values makes data borrowing and the generality of predictive modeling difficult to evaluate. We report new ED measurements derived from bomb calorimetry for six freshwater fish species (Arctic Char Salvelinus alpinus, Brown Trout Salmo trutta, kokanee Oncorhynchus nerka, Lake Trout Salvelinus namaycush, Rainbow Trout O. mykiss, and White Sucker Catostomus commersonii) and compared them to previously published data. We used our data to validate existing ED:DM models and to fit new ones. We also quantified bias that could result from borrowing inappropriate ED values for bioenergetics modeling. We collected a range of fish sizes from two reservoirs of differing productivity and measured whole‐body ED (wet‐mass basis) and DM. Our data substantially increase the range of ED data for Arctic Char, kokanee, and White Suckers. Two multispecies ED:DM models predicted the ED of our samples accurately (mean root mean square error [RMSE] < 500 J/g), even at the extremes for the range of prediction where data used for model development were limited. Taxon‐specific models performed less well (mean RMSE = 775 J/g), and some appeared highly biased (RMSE 956−1,900 J/g). Bioenergetics model simulations showed that Lake Trout prey consumption could be overestimated by as much as 22% when using borrowed EDs for Lake Trout and their prey, but prey consumption estimates fell within ±2% of observed when ED was predicted from DM. When direct measures of ED are unattainable, measurement of DM and prediction of ED from one of the published multispecies models offer a practical and accurate method for bioenergetics modeling and other studies requiring information on fish energy content.

Measurements of resting energy expenditure in surgical critically ill patients with mechanical ventilator

Objective To compare the differences between measured resting energy expenditure calculated by the indirect calorimetry with the resting energy expenditure calculated by the Harris-Benedict formula and weight formula in the mechanically ventilated surgical critically ill patients in SICU. Methods Patients mechanically ventilated in SICU of Xuanwu Hospital, from April 2014 to April 2015 were measured resting energy expenditure by the indirect calorimetry with the resting energy expenditure calculated by the Harris-Benedict formula and weight formula in the 1st, the 3rd and the 5th day. There were twenty-nine patients enrolled, thirteen males and sixteen females, measured the resting energy expenditure 188 times.The distribution of metabolism level was studied, and the resting energy expenditure measured by three methods were calculated and evaluated by paired sample t test. Results There were 177 times(62.24%)of low metabolism level, 59 times(31.38%)of normal metabolism level, and 12 times(6.38%)of high metabolism level. Eighteen patients used these three methods to calculate the energy expenditure on 1st, 3rd and 5th day: indirect calorimetry (1 627.11±323.63) kcal, (1 614.67±308.93) kcal, (1 576.11±263.96) kcal; Weight formula (1 479.44±200.24) kcal, (1 488.40±227.72) kcal, (1434.14±216.56) kcal; Harris-Benedict formula (1 777.43±253.00) kcal, (1 730.08±265.18) kcal, (1 689.33±236.69) kcal.The results calculated from Harris-Benedict formula and the weight formula were significantly different from calculated from indirect calorimetry(P<0.05). Resting energy expenditure by Harris-Benedict formula was significantly higher than calculated from indirect calorimetry (All P<0.05). Resting energy expenditure by weight formula was significantly lower than calculated from indirect calorimetry(All P<0.05). Conclusions Although Harris-Benedict formula and weight formula is convenient in clinical use, while the results calculated by them is significant different from the results calculated by indirect calorimetry. So clinical nutrition support should rely on indirect calorimetry as far as possible. Key words: Energy metabolism; Nutritional support; Indirect calorimetry; Harris-Benedict formula; Ventilators, mechanical

Orthogonal Comparison of GC-MS and 1H NMR Spectroscopy for Short Chain Fatty Acid Quantitation.

Short chain fatty acids (SCFAs) are important regulators of host physiology and metabolism and may contribute to obesity and associated metabolic diseases. Interest in SCFAs has increased in part due to the recognized importance of how production of SCFAs by the microbiota may signal to the host. Therefore, reliable, reproducible, and affordable methods for SCFA profiling are required for accurate identification and quantitation. In the current study, four different methods for SCFA (acetic acid, propionic acid, and butyric acid) extraction and quantitation were compared using two independent platforms including gas chromatography coupled with mass spectrometry (GC-MS) and 1H nuclear magnetic resonance (NMR) spectroscopy. Sensitivity, recovery, repeatability, matrix effect, and validation using mouse fecal samples were determined across all methods. The GC-MS propyl esterification method exhibited superior sensitivity for acetic acid and butyric acid measurement (LOD < 0.01 μg mL-1, LOQ < 0.1 μg mL-1) and recovery accuracy (99.4%-108.3% recovery rate for 100 μg mL-1 SCFA mixed standard spike in and 97.8%-101.8% recovery rate for 250 μg mL-1 SCFAs mixed standard spike in). NMR methods by either quantitation relative to an internal standard or quantitation using a calibration curve yielded better repeatability and minimal matrix effects compared to GC-MS methods. All methods generated good calibration curve linearity (R2 > 0.99) and comparable measurement of fecal SCFA concentration. Lastly, these methods were used to quantitate fecal SCFAs obtained from conventionally raised (CONV-R) and germ free (GF) mice. Results from global metabolomic analysis of feces generated by 1H NMR and bomb calorimetry were used to further validate these approaches.

Potential Biocides: Iodine‐Producing Pyrotechnics

AbstractCurrently there is a need for specialized pyrotechnic materials to combat the threat of biological weapons. Materials have been characterized based on their potential to produce heat and molecular iodine gas (I2) to kill spore‐forming bacteria (e. g. anthrax). One formulation, already proven to kill anthrax simulants, is diiodine pentoxide with aluminum; however, it suffers from poor stability and storage problems. The heat and iodine gas output from this mixture and candidate replacement mixtures were measured with bomb calorimetry and extraction and analysis of I2 by UV‐Vis. Of the mixtures analyzed, calcium iodate and aluminum was found to be the highest producer of I2. The heat output of this mixture and others can be tuned by adding more fuel, with the cost of some iodine. Products of combustion were analyzed by thermal analysis (SDT), XPS, XRD, and LC/MS. Evidence for various metal iodides and metal oxides was collected with these methods.

Streptococcus pneumoniae StkP kinase: binding ability with β-lactam antibiotics and correlation with drug resistance

Objective To investigate the correlation between Streptococcus pneumoniae (S.pneumoniae) StkP kinase and drug resistance and to analyze the binding ability of StkP extracellular region (EC-StkP) to β-lactam antibiotics. Methods A stkP gene knockout (ΔstkP) mutant was constructed from S. pneumoniae strain ATCC6306 by insertional inactivation method. E-test was performed to detect the minimum inhibitory concentrations (MIC) of penicillin (PCN) and cefotaxime (CTX) against ΔstkP mutant and its wild-type strain. Bioinformatic softwares were used to predict the EC-StkP of S. pneumonia strain ATCC6306, to generate the three-dimensional structure model of EC-StkP and to analyze the correlation between the structure and functions of EC-StkP. PCR was performed to amplify the extracellular segment of stkP (EC-stkP) gene and the product of it was sequenced after T-A cloning. A prokaryotic expression system of EC-stkP gene was constructed. SDS-PAGE in combination with a gel image analysis system was used to detect the expression of the recombinant EC-StkP (EC-rStkP). The expressed EC-rStkP was extracted by Ni-NTA affinity chromatography. The binding abilities of EC-rStkP to PCN and CTX were detected by isothermal titration calorimetry (VT-ITC) and surface plasmon resonance (Biacore). Results S. pneumonia strain ATCC6306 was sensitive to PCN (MIC=0.06 μg/ml) and CTX (MIC=0.12 μg/ml), but its ΔstkP mutant was resistant to the two antibiotics (PCN MIC=16 μg/ml, CTX MIC=32 μg/ml). The 295 aa segment was predicted as the extracellular region at C-end of StkP of S. pneumoniae strain ATCC6306, containing four penicillin-binding proteins and Ser/Thr kinase-associated (PASTA) domains. The cloned EC-stkP segment and the EC-stkP segment in GenBank shared 99.6% similarity in nucleotide sequence and 100% in amino acid sequence. The constructed prokaryotic expression system for EC-stkP gene expressed EC-rStkP in soluble form. Both PCN and CTX could bind to EC-rStkP and CTX was better than PCN in term of binding ability. Conclusion The stkP gene of S. pneumonia is closely related to drug resistance and the encoded protein, Ser/Thr kinase StkP, can recognize and bind to β-lactam antibiotics. Key words: Streptococcus pneumoniae; Ser/Thr kinase; β-lactam antibiotics; Binding ability; Gene knockout/drug resistance

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espanolLa caracterizacion de arcillas procedentes de la Formacion Guayabo del Area Metropolitana de Cucuta, Norte de Santander (Colombia) es presentada. Los resultados obtenidos de estos analisis permiten determinar las propiedades de estas arcillas y potenciar su uso en la fabricacion de materiales de construccion y en la elaboracion de nuevos materiales ceramicos, generando impactos tecnologicos, economicos y sociales en la region, pues se podra competir con productos de calidad en los exigentes mercados nacionales e internacionales. Es asi que a traves de este trabajo se realizo la caracterizacion quimica, mineralogica, termica y fisicoceramica, para determinar la estructura, composicion y comportamiento de estas materias primas. Las muestras se obtuvieron de dos puntos diferentes de la formacion, ubicados en los municipios del Zulia y Villa del Rosario. Para la evaluacion se utilizo la informacion obtenida de la caracterizacion quimica mediante Fluorescencia de Rayos X (FRX), caracterizacion mineralogica mediante Difraccion de Rayos X (DRX) e infrarrojo con transformada de Fourier (FTIR), caracterizacion termica mediante analisis termico gravimetrico (TGA) y calorimetria diferencial de barrido (DSC); y finalmente caracterizacion fisico-ceramica. Los resultados indican que los minerales arcillosos estan constituidos por aluminosilicatos hidratados con presencia de algunas impurezas como sodio, hierro, potasio, calcio, titanio por lo que presentan capacidad de ser sometidas a esfuerzos para su conformado a traves de procesos de extrusion. Se evidencia que aunque ambas muestras se encuentran en diferentes municipios del area metropolitana de Cucuta, presentan caracteristicas similares en fases cristalinas, grupos funcionales, comportamientos termicos y propiedades ceramicas. EnglishThe characterization of clays from the Guayabo Formation at the Cucuta Metropolitan Area, Norte de Santander (Colombia) is presented. The results of these analyzes allow to determine the properties of these clays and to enhance their use in the manufacture of building materials and in the development of new ceramic materials, creating technological, economic and social impacts in the region, as they can compete with high quality product in the demanding national and international markets. Thus, through this work, chemical, mineralogical, thermal and physical-ceramic characterizations were performed to determine the structure, composition and behavior of these raw materials. The samples were obtained from two different points of the geological formation, located at the municipalities of Zulia and Villa del Rosario. The information obtained from the chemical characterization, mineralogical, thermal and physical- ceramic, using the techniques of X-ray fluorescence, X-ray diffraction, thermal gravimetric analysis, Differential Scanning Calorimetry and Infrared Fourier Transform, was used for evaluation. The results indicate that the clay minerals are composed of hydrous aliminosilicates with presence of some impurities such as sodium, iron, potasium, calcium, titanium and this have ability to be subjected to efforts for shaping by extrusion processes. It is shown that although both samples are from different municipalities in the metropolitan area of Cucuta, have similar characteristics in crystalline phases, functional groups, thermal behavior and ceramic properties. portuguesA caracterizacao das argilas da formacao Guayabo da Area Metropolitana, Cucuta Norte de Santander (Colombia) e apresentado. Os resultados destas analises permitem a determinacao das propriedades destas argilas e promovem a sua utilizacao na fabricacao de materiais de construcao e no desenvolvimento de novos materiais cerâmicos, gerando impactos tecnologicos, economicos e sociais na regiao, Assim, estes poderao competir com os produtos de qualidade em os exigentes mercados nacionais e internacionais. Entao, com o desenvolvimento deste trabalho, foi possivel a caracterizacao quimica, mineralogica, termica e fisico-cerâmica para determinar a estrutura, composicao e comportamento destes materiais. As amostras foram obtidas de dois pontos diferentes da formacao, localizadas no municipio “El Zulia” e “Villa del Rosario”. Para a avaliacao se utilizou a informacao obtida da caracterizacao quimica atraves de Fluorescencia de Raios-X (FRX), a caracterizacao mineralogica atraves de Difracao de Raios-X (DRX) e infravermelho com transformada de Fourier (FTIR), a caracterizacao termica foi feita atraves de analise termico gravimetrico (TGA) e calorimetria de varredura diferencial (DSC), e finalmente a caracterizacao fisico-cerâmica. Os resultados indicarem que os minerais argilosos consistem de alumino-silicato hidratado com a evidencia de algumas impurezas como sodio, ferro, potassio, calcio e titânio; e assim entao, que estes materiais apresentam capacidade de ser submetidos a esforcos para seu formado atraves de processos de extrusao. No entanto, e evidente que embora ambas amostras se coletaram em diferentes municipios da area metropolitana de Cucuta apresentaram caracteristicas semelhantes em fases cristalinas, grupos funcionais, nos seus comportamentos termicos e nas suas propriedades cerâmicas.

Seven-coordinated chelate [Cd(SCZ)3·H2O](HTNR)2(H2O)2: Synthesis, crystal structure and energetic properties

ABSTRACTTo deepen the study on heptacoordinate transition metal coordination complexes, a novel seven-coordinated coordination compound [Cd(SCZ)3·H2O](HTNR)2(H2O)2 (1, SCZ = semicarbazide, H2TNR = styphnic acid) was synthesized and characterized by elemental analysis and FTIR spectroscopy. Single-crystal X-ray diffraction analysis revealed that 1 crystallizes in the triclinic space group P-1. The thermal decomposition mechanism of 1 was studied by differential scanning calorimetry (DSC). The non-isothermal kinetics parameters were calculated by the Kissinger's method and Ozawa-Doyle's method, respectively. Sensitivity tests revealed that 1 is insensitive to mechanical stimuli. The heat of combustion was measured by oxygen bomb calorimetry and the enthalpy of formation was calculated.

MICROWAVE MEDIATED SYNTHESIS OF POLY(AZIDOMETHYLSTYRENE-TETRAZOLE) (PAST) AS AN ENERGETIC POLYMER

The poly(azidomethylstyrene-tetrazole) (PAST) was successfully synthesized by azidation of a copolymer substrate such as poly(chloromethylstyrene-acrylonitile) under microwave irradiation. This method was very simple, rapid and carried in a controllable way. In this greener approach, the chloro group of copolymer was easily replaced by azide group and the cyanide group was converted to tetrazole moiety under microwave irradiation. The synthesized copolymers were characterized by spectral analysis and thermal properties were estimated using thermogravimetric analysis and differential scanning calorimetry.

A readily accessible multifunctional probe: simultaneous recognition of the cation ZN²⁺ and the anion F⁻ via distinguishable wavelengths

The probe 1 was readily prepared via condensation of 8-formyl-7-hydroxy-coumarin and carbonic dihydrazide in a one-step procedure. Probe 1 exhibited high sensitivity and selectivity towards Zn²⁺ and F⁻ through a “turn-on” fluorescence response and/or ratiometric colorimetric response with low detection limits of the order of 10-8 M. The complex behaviour was fully investigated by spectral titration, isothermal titration calorimetry, 1H NMR spectroscopic titration and mass spectrometry. Interestingly, probe 1 not only recognizes the cation Zn²⁺ and the anion F⁻, but can also distinguish between these two ions via the max wavelength in their UV-vis spectra (360 nm for 1-Zn²⁺ versus 400 nm for 1-F⁻ complex) or their fluorescent spectra (λₑₓ / λₑm = 360 nm/ 454 nm for 1-Zn²⁺ versus λₑₓ / λₑm = 400 nm/ 475 nm for 1-F⁻ complex) due to their differing red-shifts. Additionally, probe 1 has been further explored in the detection of Zn²⁺ in living cells.

Modeling rates of DOC degradation using DOM composition and hydroclimatic variables

AbstractThe fluvial fluxes of dissolved organic carbon (DOC) from peatlands form an important part of that ecosystem's carbon cycle, contributing approximately 35% of the overall peatland carbon budget. The in‐stream processes acting on the DOC, such as photodegradation and biodegradation, can lead to DOC loss and thus contribute CO2 to the atmosphere. The aim of this study was to understand what controls the rates of DOC degradation. Water samples from a headwater, peat‐covered catchment, were collected over a 23 month period and analyzed for the DOC degradation rate and dissolved organic matter (DOM) composition in the context of hydroclimatic monitoring. Measures of DOM composition included 13C solid‐state nuclear magnetic resonance spectroscopy, bomb calorimetry, and elemental analysis. Regression analysis showed that there was a significant role for the composition of the DOM in controlling degradation with degradation rates significantly increasing with the proportion of aldehyde and carboxylic acid functional groups but decreasing with the proportion of N‐alkyl functional groups. The highest rates of DOC degradation occurred when aldehyde functionality was at its greatest and this occurred on the recession limb of storm hydrographs. Including this knowledge into models of fluvial carbon fate for an 818 km2 catchment gave an annual average DOC removal rate of 67% and 50% for total organic carbon, slightly lower than previously predicted. The compositional controls suggest that DOM is primarily being used as a ready energy source to the aquatic ecosystem rather than as a nutrient source.

Postoperative resting energy expenditure in children with congenital heart disease

Objective To determine postoperative resting energy expenditure (REE) in children with congenital heart disease (CHD) requiring open heart surgery, to compare measured resting energy expenditure(MREE) with current predictive equations (PEE), and to investigate the possible influencing factors on the metabolic status of the postoperative CHD children. Methods From February 2015 to June 2015, 150 ventilated children admitted to the cardiac intensive care unit after surgery for congenital heart disease in Shanghai Children's Medical Center were enrolled consecutively. Indirect calorimetry (IC) measurements were performed using metabolic cart 4 hours after surgery. General clinical data were recorded. Results Totally 104 male and 46 female patients were enrolled, with a median age of 14 months (8.3-36.0 months). The non-protein respiratory quotient of patient was 0.79±0.20, MREE was (264.76±61.74)kJ/(kg·d), and PEE using Schofield equations was (278.51±93.42)kJ/(kg·d). Although there was no significant differences (P=0.096) between MREE and PEE, the agreement was poor between them (R2=0.119). Multivariate stepwise regression analysis showed that MREE had significant positive correlation with risk adjustment in congenital heart surgery(RACHS-1) score(P=0.012) and negative correlation with age (P=0.010). Up to 97.33% of children(146/150) had lower energy intake compared with MREE on the 1st postoperative day. Conclusions MREE does not increase after surgery in CHD children; however, the substrate utilization is influenced. Factors influencing the postoperative REE include RACHS-1 score and age. The energy intake at 1st day after surgery is generally lower than REE in these children. Key words: Children; Congenital heart disease; Resting energy expenditure; Indirect calorimetry