Stable carbon isotope analysis of different tissues of beef animals in relation to their diet

As part of a larger experiment, 31 young bulls, divided into three groups, were given different diets containing either C(3) plants or a combination of C(3) and C(4) plant-based feeds in three feeding periods before slaughter. Variation in the proportion of C(4) plant material in the diets was made by including or not maize or maize-derived ingredients, whereas the other dietary constituents were from C(3) plants. Analysis of stable carbon isotope ratios (delta(13)C value) was performed on different tissues taken at slaughter: blood, plasma, liver, kidney fat, hair, muscle and ruminal contents. Blood and plasma samples were also taken at the beginning of each period. A highly significant difference was found in the delta(13)C values of blood and plasma samples taken from animals that had received a diet of only C(3) plants or with 59% C(4) material for 70 days. The delta(13)C values of all different samples taken at slaughter were highly significantly different between the three feeding groups that had received diets with 0, 13.5 or 35% C(4) material for on average 137, 139 and 83 days, respectively. For the three groups, samples of hair, muscle, plasma, whole blood and liver were significantly enriched in (13)C compared with the diet (except for liver in one group), whereas kidney fat was significantly depleted. The proportion of C(4) plant material could be accurately estimated from the delta(13)C values of different tissue samples. Stable carbon analysis of different tissues from beef animals can be used to trace back diets containing variable proportions of C(3) and C(4) plant material.     

Comparison of the acidity of residual silanol groups in several liquid chromatography columns

The silanol acidity of Waters Resolve C18, Waters Resolve silica, Waters Symmetry C18, Waters Symmetry silica, Waters XTerra MS C18 and underivatized XTerra columns has been measured from the retention of LiNO3 with a methanol/water (60:40) mobile phase buffered to different pH values. The Li+ cation is retained by cationic exchange with the background cation of the mobile phase (Na+) through the ionized silanols. The number of active silanols increases in the order: XTerra MS C18 < Symmetry C18 < underivatized XTerra < Resolve C18 < Resolve silica approximately equal to Symmetry silica. XTerra MS C18 does not present any residual silanol acidity up to s(s)pH 10.0 (pH in 60% methanol) as measured by LiNO3. The underivatized XTerra packing and Symmetry C18 present active silanols only at s(s)pH values higher than 7.0. For the other three columns, two different types of silanols with different acidity (s(s)pKa values about 3.5-4.6 and 6.2-6.8, respectively) have been observed. Symmetry C18 shows evidence of the presence of active basic sites that retain NO3- by anionic exchange.     

Synthesis of a Novel UV Curable Aqueous Dispersion Polyurethane PDHA-PEDA-PU and the Properties of Cured Film

Because of the merits in environmental protection and lower energy consumption, ultraviolet (UV) curable coatings have been gained more and more attention and speedy development in the past decades. UV curable waterborne polyurethane has been employed pop…     

Directed, selective insertion of single molecules into patterned self-assembled monolayers of alkanethiols with different chain lengths

Pd(ii) pincer adsorbate molecules (1) were inserted into self-assembled monolayers (SAMs) of alkanethiols with different chain lengths (C(8) to C(18)) on annealed gold substrates. Their presence was brought to expression by reaction of with Au nanoclusters bearing phosphine moieties (2). The surface-confined Au nanoclusters were observed only on the shorter chain SAMs (C(8)SH to C(16)SH) and not on C(18)SH SAMs. This is attributed to the longer chain length of C(18)SH preventing the insertion of pincer molecules. Microcontact printing (microCP) with C(18)SH on unannealed gold substrates and the subsequent immersion of the substrates into C(8)SH, C(10)SH, C(12)SH, or C(16)SH solutions, yielded a series of patterned SAMs that have areas of thiols of different chain lengths. Insertion of 1 followed by expression using 2, or insertion of 3 showed inserted molecules only in the shorter chain SAM areas. The absolute particle densities in the former case were higher than on the corresponding homogeneous SAMs on annealed substrates, probably due to larger numbers of defects in the SAMs on unannealed substrates.     

More on the phase diagram of Laponite

The phase diagram of a charged colloidal system (Laponite) has been investigated by dynamic light scattering in a previously unexplored range of salt and clay concentrations. Specifically, the clay weight and salt molar concentrations have been varied in the ranges C(w) = 0.004 divided by 0.025 and C(s) = (1 x 10(-3) divided by 5 x 10(-3)) M, respectively. As in the case of free salt water samples (C(s) approximately = 1 x 10(-4) M), an aging dynamics toward two different arrested phases is found in the whole examined C(w) and C(s) range. Moreover a transition between these two different regimes is found. It is clear from these measurements that a revision of the phase diagram is necessary and a new "transition" line between two different arrested states is drawn.     

The aqueous phase behavior of polyion-surfactant ion complex salts mixed with nonionic surfactants

The aim of this work was to study intermolecular interactions in systems containing charged polyion (polyacrylate, PA(-)), charged surfactant (C(16)TA(+)) and nonionic surfactant (C(12)E(5) or C(12)E(8)). To achieve this we have created four different phase diagrams using two different so-called complex salts, C(16)TAPA(25) and C(16)TAPA(6000), both consisting of positively charged surfactant (C(16)TA(+)) with polyacrylate (PA(-)) as counterions (no simple salt). The difference between the salts is the length of the polyion (25 or 6000 monomers). Both are insoluble in water. The results revealed that decreasing polyion length and increasing the PEO chain length of the nonionic surfactant were important factors for increasing the solubility of the complex salt. We also found that the curvature effects are quite small at low water content when gradually exchanging C(12)E(8) for either one of the complex salts while there is a gradual change in curvature for the systems containing C(12)E(5). Another interesting observation was the possibility for relatively large amounts of complex salt to be incorporated into a V(1) (Ia3d, bicontinuous) phase in the C(12)E(8)-containing systems. This gives rise to several questions regarding arrangements and dynamics of the polyion in this phase. In the dilute regime several different liquid crystalline phases can coexist with a dilute liquid phase containing the nonionic surfactant.     

C60的产生与石墨晶面的关联（I）

Ｃ_（６０）的产生与石墨晶面的关联（Ｉ）谢兆雄，刘朝阳，林逢辰，王春儒，郑兰荪（厦门大学化学系固体表面物理化学国家重点实验室厦门，３６１００５）关键词Ｃ_（６０），激光溅射，石墨晶面Ｓｍａｌｌａｙ等［１］曾以激光在超声分子束喷口的喉道处蒸发石墨得到了Ｃ...     

气相反应76/70C_(70)=C_(76)(D_2)热力学函数的计算

采用统计热力学方法计算了气相C76（D2）的标准热力学函数，在此基础上计算了不同温度下气相反应76／70C70＝C76（D2）的热力学函数，讨论了C70与C76（D2）之间相互转化的热力学条件．结果表明，气相中温度低于536K时C70转化为C76（D2），温度高于536K时气相中C76（D2）转化为C70。     

Fabrication and characterization of multilayer films from amphiphilic poly(p-phenylene)s

Over the past two decades, considerable efforts have been devoted to the development of conjugated polymeric materials for electronic applications due to the tunability of their properties through variation of their chemical structure. The LB technique is one of the most effective and precise methods for controlling the organization and thereby the properties of polymer films at the nanoscale for device fabrication. A detailed study was performed on the Langmuir-Schaefer (LS) monolayer and Langmuir-Blodgett-Kuhn (LBK) multilayer formation of newly designed conjugated poly(p-phenylene)s (C(n)PPPOH), incorporated with alkoxy groups with different chain lengths (C(6)H(13)O-, C(12)H(25)O-, and C(18)H(37)O-) and hydroxyl groups on the polymer backbone. The monolayer formed at the air-water interface was characterized using surface pressure-area isotherms, including hysteresis measurements. The films were then transferred to different hydrophilic solid substrates and analyzed using surface plasmon resonance spectroscopy, UV-vis spectroscopy, fluorescence spectroscopy, and AFM measurements. The results showed that the polymer with a short alkoxy chain (C(6)PPPOH) forms uniform monolayers at the air-water interface and can be transferred as multilayer films compared to C(12)PPPOH and C(18)PPPOH. The observed film thicknesses measured by SPR and AFM studies were similar to the theoretical value obtained in the case of C(6)PPPOH, whereas this was not the case with the other two polymers. The present study shows that the polymer C(n)PPPOH with short alkoxy chain can be transferred onto different solid substrates for device fabrication with molecular level control.     

Chemical initiation mechanism of maleic anhydride grafted onto styrene-butadiene-styrene block copolymer

The mechanism of grafting styrene-butadiene-styrene (SBS) tri-block copolymer with maleic anhydride (MAH) initiated by benzoperoxide (BPO) or 2,2^′-azo-bis-isobutyronitrile (AIBN) was studied by FTIR and ¹H NMR spectroscopies. The variation of CC (double bond) content in SBS-g-MAH was used to verify the different graft mechanisms of BPO and AIBN, indicating that the chemical initiation mechanisms of MAH grafted onto SBS of AIBN is different from that of BPO. The graft reaction occurs by addition on CC for AIBN, while by removal of an allylic hydrogen atom from SBS and by addition on CC at the same time for BPO. The graft efficiency of AIBN is higher than that of BPO in this system.     

Structural aspects of two-stage dimerization in an ionic C60 complex with bis(benzene)chromium: Cr(C6H6)2.C60.C6H4Cl2

Single crystals of the ionic C60 complex with bis(benzene)chromium: {Cr(I)(C6H6)2(.+)}.(C60.-)).C6H4Cl2 (1) were obtained. The crystal structure of 1 shows the presence of monomeric C60.- radical anions at 250 K and the formation of single-bonded (C60-)2 dimers at 90 K. The dimerization is realized in two types of the C60.-) pairs with different interfullerene center-to-center distances of 10.052 and 10.279 A arranged in zigzag chains along the a-direction. As a result, two symmetrically independent (C60-)2 dimers found in 1 at 90 K have different environments, intercage C-C bond lengths and C60- center-to-center distances. Such differences should provide different thermal stability of these dimers and result in the appearance of two stages at the dimerization. Indeed, according to SQUID measurements, the magnetic moment of 1 decreases stepwise at the dimerization in two temperature ranges at 240-200 and 200-160 K.     

基于3,4-乙烯二氧噻吩和吡咯-3-甲酸的共聚物薄膜的制备、表征及电致变色性能

以3,4-乙烯二氧噻吩(EDOT)和吡咯-3-甲酸(P3C)为共聚单体,EDOT和P3C分别按物质的量比1∶1,3∶1,5∶1,10∶1配比,通过电化学聚合制得了4种聚(3,4-乙烯二氧噻吩-吡咯-3-甲酸)薄膜,并依次命名为P(EDOT∶P3C)-1,P(EDOT∶P3C)-3,P(EDOT∶P3C)-5和P(EDOT∶P3C)-10.光谱电化学测试结果表明,4种共聚物薄膜都具有优良的电致变色性能,同时具有较好的电化学活性和较高的光学对比度.与聚3,4-乙烯二氧噻吩(PEDOT)相比,P(EDOT∶P3C)能展示更丰富的颜色变化,如P(EDOT∶P3C)-1薄膜随着电压的变化,可呈现从暗红色、浅褐色、灰蓝色到蓝色的变化.此外,基于EDOT和P3C以及钛氧簇[Ti_7(OEt)_(19)O_5(CoBr)],我们还设计合成了含钛共聚物薄膜P(EDOT∶P3C)-1-Ti,该薄膜不仅具有电致变色性能,而且还具有电催化氧化水的活性.     

Relaxation during polymerization on slow heating and the vibrational heat capacity of the polymers

The real and imaginary components of the complex heat capacity, C(p) (') and C(p) ("), and C(p,app) have been measured in real time during the linear chain polymerization on 12 K/h heating of six different (partially) polymerized states of a stoichiometric mixture of cyclohexylamine and diglycidyl ether of bisphenol A. Their C(p,app) shows a sigmoid shape rise with different onset temperatures T(onset), which is followed by a deep exotherm as the viscosity decreases and further polymerization occurs at different rates. The rates of their enthalpy decrease on polymerization determined by subtracting C(p) (') from C(p,app) differ but C(p) (') and C(p,app) of their final states are the same. The relaxation time increases with polymerization and decreases with an increase in T. C(p) (') rises in a sigmoid shape manner, and C(p) (") shows a peak when the relaxation time of the polymerized state is equal to the inverse of the temperature modulation frequency, whether polymerization occurs or not. The unrelaxed or vibrational heat capacity C(p,vib) of the polymers at T>T(onset) is close to C(p) of their glassy state at T相似文献   

Electron-induced reactions in condensed films of acetonitrile and ethane

Reactions in pure and mixed films of C(2)H(6) and CD(3)CN deposited on a Au surface at 35 K have been induced by low-energy electrons and investigated by Thermal Desorption Spectrometry (TDS). The incident electron energy (E(0)) was varied between 5 and 16 eV and a number of different products were identified. Beside the main products, CD(4), CD(3)H, and C(2)D(6), molecules resulting from atom scrambling during radical chain reactions (C(2)H(5)D) and recombination products (CD(3)CD(2)CN and C(2)H(5)CD(3)) were identified while others were characteristically absent. The quantity of the different products varied with E(0). The observed electron-driven processes are in accord with previous findings from gas phase experiments on dissociative electron attachment and electron impact ionization. On this basis, reaction mechanisms leading to the formation of the observed products are suggested for different ranges of E(0).     

Geometric and electronic properties of endohedral Si @ C74

The generalized gradient approximation based on density functional theory is used to analyze the geometric and electronic properties of Si @ C(74). It is found that among the five possible optimized geometries of Si @ C(74), the most favorable endohedral site of Si atom is under the center of a pentagon ring on the sigma(h) plane, i.e., Si @ C(74)-5, which is different from the center stable site for Si in C(74) calculated by the semiempirical molecular orbital calculations and molecular mechanics calculations, and it is also different from the stable site, i.e., under a [6, 6] bond along the C(2) axis on the sigma(h) plane in C(74) for metal atoms Ba, Ca, and Eu. The deformation charge density on the sigma(h) plane reveals that the Si-C bonds in Si @ C(74)-5 have covalent character, while the Mulliken charge analysis together with a longer Si-C bond length reveals that the Si-C bonds in Si @ C(74)-5 have ionic character. Therefore, we infer that Si-C bonds in Si @ C(74)-5 contain both covalent and ionic characters.     

Molecular state and distribution of fullerenes entrapped in sol-gel samples

A novel synthetic method that can encapsulate fullerene molecules (pure C60, pure C70, or their mixture) over a wide range of concentrations ranging from micromolar to millimolar in hybrid glass by a sol-gel method without any time-consuming, complicated, and unwanted extra steps (e.g., addition of a surfactant or derivatization of the fullerenes) has been successfully developed. The molecular state and distribution of encapsulated fullerene molecules in these sol-gel samples were unequivocally characterized using newly developed multispectral imaging techniques. The high sensitivity (single-pixel resolution) and ability of these instruments to record multispectral images at different spatial resolutions (approximately 10 microm with the macroscopic instrument and approximately 0.8 microm with the microscopic instrument) make them uniquely suited for this task. Specifically, the imaging instruments can be used to simultaneously measure multispectral images of sol-gel-encapsulated C60 and C70 molecules at many different positions within a sol-gel sample in an area either as large as 3 mm x 4 mm (with the macroscopic imaging instrument) or as small as 0.8 microm x 0.8 microm (with the microscopic instrument). The absorption spectrum of the fullerene molecule at each position can then be calculated either by averaging the intensity of a 15 x 15 square of pixels (which corresponds to an area of 3 mm x 4 mm) or from the intensity of a single pixel (i.e., an area of about 0.8 microm x 0.8 microm), respectively. The molecular state and distribution of fullerene molecules within sol-gel samples can then be determined from the calculated spectra. It was found that spectra of encapsulated C60 and C70 measured at five different positions within a sol-gel sample were similar not only to one another but also to spectra measured at six different times during the sol-gel reaction process (from t = 0 to 10 days). Furthermore, these spectra are similar to the corresponding spectra of monomeric C60 or C70 molecules in solution. Similarly, spectra of sol-gel samples containing a mixture of C60 and C70 were found to be the same at five different positions, as well as similar to spectra calculated from an average of the spectra of C60 and C70 either encapsulated in a sol-gel or in solution. It is evident from these results that C60 and C70 molecules do not undergo aggregation upon encapsulation into a sol-gel but rather remain in their monomeric state. Furthermore, entrapped C60 and C70 molecules in their monomeric state were distributed homogeneously throughout the entire sol-gel samples. Such a conclusion can be readily, quickly, and easily obtained, not with traditional spectroscopic techniques based on the use of a single-channel detector (absorption, fluorescence, infrared, Raman) but rather with the newly developed multispectral imaging technique. More importantly, the novel synthetic method reported here makes it possible, for the first time, to homogenously entrap monomeric fullerene molecules (C60, C70, or their mixture) in a sol-gel at various concentrations ranging from as low as 2.2 mM C60 (or 190 microM C70) to as high as 4.2 mM C60 (or 360 microM C70).     

Determination of the Absolute Configuration of Amines and alpha-Amino Acids by (1)H NMR of (R)-O-Aryllactic Acid Amides

(R)-O-Aryllactic acid (ROAL) amides derived from alpha-chiral primary amines and alpha-amino acid esters show different chemical shifts in (1)H NMR spectroscopy (300 MHz) depending on their configuration. Molecular mechanics, semiempirical calculations, and (1)H NMR studies suggest that, in solution, these amides prefer an ap-Z conformation with the C(alpha)OAr and C=O groups close to anti-periplanar as in the case of mandelic acid amides. The proposed conformational preference is different from that of the ROAL esters (C(alpha)H and C=O groups in a syn-periplanar conformation). The conformational model for ROAL amides allows the absolute configuration assignment of primary amines and alpha-amino acid esters according to the relative position of the aryl group and the substituents on the amine moiety, and also their enantiomeric composition.     

Comparison of extraction methods for the recovery, amplification and species-specific analysis of DNA from bone and bone meals

We report the effect of several parameters on the efficiency of recovery of DNA from animal bones. The effects of preheating the samples (at either 60 degrees C or 100 degrees C) at different intervals (from 1 h to overnight) in different media (water, 0.5 M ethylenediaminetetraacetic acid (EDTA), or 0.5 M EDTA + 0.05% sodium dodecyl sulfate (SDS) were investigated. The effect of slight (5 min) or intense (30 min) pretreatments with ultrasound was also evaluated. Several different treatments with proteinase K (ranging from 200 to 800 microg, and lasting from 1 to 3 h) at 65 degrees C were also considered. Additionally, two different DNA extraction methods (based on silica resins and purification columns, respectively) were evaluated. The recovery of DNA from the samples was 40% higher when the bones were preheated in 0.5 M EDTA at 60 degrees C for 1 h, this being followed by treatment with 800 microg of proteinase K for 3 h. The DNA thus obtained was successfully amplified by polymerase chain reaction (PCR) using a set of primers specific to a 359 bp region of the mitochondrial cytochrome b gene, and the species of origin were identified by visualizing the restriction fragment length polymorphism (RFLP) with the endonucleases PalI and MboI.     

Investigation of the radioprotective properties of some tea polyphenols

The influence of tea and coffee flavonoids (−)-epicatechin (EC) and (+)-catechin (C) on the effect of γ-irradiation of DNA molecules in solutions was investigated. The concentrations of these and other components in different samples of black and green tea were analyzed by the capillary electrophoresis. It was determined from the experimental data obtained by different methods (circular dichroism and UV spectra, viscosimetry and optical investigations) that C and EC do not form complexes with DNA in solutions. It was shown that C and EC have radioprotective properties, being scavengers of the water radiolysis products.     

Analysis of IR spectra of carbon clusters trapped in noble gas matrices using algorithms based on digital filtering techniques

IR spectra of carbon clusters C(n) (n>/=3) trapped in noble gas matrices (Ar and Kr) at temperatures of 13, 30 and 35 K are analyzed using algorithms based on digital filtering techniques and non-linear least-squares fitting. The spectral features at different temperatures and in different matrices are discussed. The majority of the resolved lines are assigned to C(n) cluster species based on data obtained via quantum chemical computations and from tunable laser IR spectrometry of C(n) species in the gas phase. A complete analysis of the IR spectra is available upon request.