Structure of starches extracted from near isogenic wheat lines

Differential scanning calorimetry (DSC), acidic hydrolysis and different physico-chemical approaches were used to study thermodynamic and structural characteristics of starches from near-isogenic wheat lines to establish the effect of different combinations of active granule-bound starch synthase isoforms, taking part in amylose biosynthesis, on the structure and thermodynamic properties of starches. Obtained results suggest that the effect of different GBSS I combinations is realized through altered amylose localization within starch granules, reflecting in changes of melting temperature of crystalline lamellae (T _m) and rates of acidic hydrolysis. It has also been demonstrated that changes in T _m values for native wheat starches are determined by amylose content in amylopectin clusters.     

Comparative characteristics of proteins of cottonplant lines differing in the strength of the fiber

The enzymes and proteins of the fibers of two lines of cotton plant differing in the strength of the fiber have been investigated. It has been shown that the activities of glucan synthetase and peroxidase rise as the fiber matures, while the activities of β-(1-3)-glucanase and cellulase fall. The specific enzymatic activities of peroxidase and glucan synthetase in the L-175 line, distinguished by a stronger fiber, are higher than for the L-466 line with a weaker fiber. The activity of glucanase changes according to the strength of the fiber. In a study of the protein composition of cotton fibers, polypeptides with molecular masses of 28 and 39 kDa were found among the proteins responsible for the strength of the fiber. A. S. Sadykov Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 162 70 71. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 530–536, July–August, 1998.     

Comparative properties of cellulose nano-crystals from native and mercerized cotton fibers

Stable aqueous suspensions of cellulose nano-crystals (CNCs) were fabricated from both native and mercerized cotton fibers by sulfuric acid hydrolysis, followed by high-pressure homogenization. Fourier transform infrared spectrometry and wide-angle X-ray diffraction data showed that the fibers had been transformed from cellulose I (native) to cellulose II (mercerized) crystal structure, and these polymorphs were retained in the nanocrystals, giving CNC-I and CNC-II. Transmission electron microscopy showed rod-like crystal morphology for both types of crystals under the given processing conditions with CNC-II having similar width but reduced length. Freeze-dried agglomerates of CNC-II had a much higher bulk density than that of CNC-I. Thermo-gravimetric analysis showed that CNC-II had better thermal stability. The storage moduli of CNC-II suspensions at all temperatures were substantially larger than those of CNC-I suspensions at the same concentration level. CNC-II suspensions and gels were more stable in response to temperature increases. Films of CNC and Poly(ethylene oxide) were tested. Both CNC-I/PEO and CNC-II/PEO composites showed increased tensile strength and elongation at break compared to pure PEO. However, composites with CNC-II had higher strength and elongation than composites with CNC-I.     

Effects of fiber physical and chemical characteristics on the interaction between endoglucanase and eucalypt fibers

Roles played by fiber physical and chemical characteristics in enzymatic hydrolysis of cellulosic materials were investigated by analyzing the interaction between an endoglucanase complex and eucalypt kraft fibers. PFI refining was employed to create the difference of fiber size distribution and morphology. Oxygen delignification and bleaching were employed to prepare fibers with different lignin and pentosan contents. The enzyme accessibility was monitored by adsorption at 4 °C and during hydrolysis at 40 °C. Molecular weight changes and reducing sugar released were monitored for digestibility of the samples. Greater maximum adsorption capacities of the enzymes were shown for the pulps with shorter and wider fibers and more fine fractions after refining. Highest amount of enzyme was adsorbed onto fibers with the least lignin contents at 4 °C. Fewer desorbed from fibers with higher lignin contents during hydrolysis at 40 °C. For unrefined fibers, less molecular weight reductions were observed for fibers with higher lignin contents. However, extensive fibrillation by refining negated the effects of lignin on the action of endoglucanase, similar molecular weight reductions were observed for fibers with three different lignin contents. Refining could be able to expose more reaction sites on the fiber surface, hence the impacts of lignin and pentosan diminished during hydrolysis for refined fibers.     

Role of micro-crystalline parameters in the physical properties of cotton fibers

Karnataka state in India is very well known for its cotton cultivation and there are innumerable varieties of these cotton fibers. Although, the yield and other types of characterization have been carried out on these fibers, the structure-property relation is not well studied till today. We have examined four different raw cotton fibers using Wide Angle X-ray Scattering (WAXS) technique and also we have computed micro-crystalline parameters. This study brings out the structure-property relation in cotton fibers.     

Surface properties of bamboo fiber and a comparison with cotton linter fibers

In order to understand the different touch senses from bamboo and cotton fibers, the surface properties of bamboo fiber, e.g., the surface free energy, the Lifshitz–van der Waals force, and Lewis acid and base components have been determined using the column wicking technique. Taking the traditional cotton linter fiber as a reference, this paper shows that both these fibers have the similar surface free energies. However, a big difference between these two fibers which has been importantly observed is that the bamboo fiber having greater Lewis acid component seems to be double than the cotton linter fiber. Since water has been found to have such surface property, it is suggested that the bamboo fiber touch in the skin of people may like the touch between water and skin of people. Meanwhile, other surface properties of these two fibers are compared.     

Cool temperature hinders flux from glucose to sucrose during cellulose synthesis in secondary wall stage cotton fibers

Current knowledge about the integration of cellulose synthesis into cellular carbon metabolism and the cool temperature sensitivity of cellulose synthesis is reviewed briefly. Roles for sucrose synthase (to channel UDP-glucose to the cellulose synthase) and sucrose phosphate synthase (to recycle the fructose released by sucrose synthase to more sucrose) in secondary wall cellulose synthesis are described. Data are presented that implicate sucrose synthesis within cotton fibers as a particularly cool temperature-sensitive step in the partitioning of carbon to cellulose. Sugar metabolism during fiber secondary wall deposition was analyzed in in vitro cultures of ovules from two cultivars of Gossypium hirsutum L. (cv. Acala SJ-1 and cv. Paymaster HS 200), which had different levels of cool temperature sensitivity. The sizes of the sucrose, glucose, and fructose pools within fibers at 4 and 7 h after a temperature shift to 15 or 34 °C did not change in either cultivar. Feeding exogenous U-¹⁴C-glucose in pulse and pulse/chase experiments showed that uptake of glucose and transport through the ovule into fibers occurred at the same rate at 34 and 15 °C. In contrast, the flux from glucose to sucrose within fibers was greatly hindered at 15 °C in both cultivars. Since sucrose is the preferred donor of UDP-Glc to the cellulose synthase during secondary wall deposition, this sensitivity in sucrose synthesis is likely to at least partially explain the cool temperature sensitivity of cotton fiber cellulose synthesis that is observed in the field.     

Changes in sugar composition and cellulose content during the secondary cell wall biogenesis in cotton fibers

Two cotton cultivars TX19 and TX55 (Gossypium hirsutum L. cv.) were planted in the greenhouse and fibers were harvested at different stages of development. The percentage of sugars present on the fibers was determined by High Performance Liquid Chromatography and the cellulose content was determined using the anthrone method. The percentage of sugars (sucrose, glucose, fructose, and galacturonic acid) showed statistically significant changes during fiber development. The decrease in the percentages of these sugars as the secondary cell wall develops was associated with an increase in the cellulose content. It is important to point out that these analyses were done on intact fibers, no cell wall extractions and purifications were performed.     

Spectroscopic analyses and chemical transformation for structure elucidation of two novel indole alkaloids from Gelsemium elegans

Two new monoterpenoid oxindole alkaloids, gelsevanillidine (1) having an additional vanillin residue on gelsenicine-type alkaloid and gelseoxazolidinine (2) possessing an unusual oxazolidine ring, were isolated from Gelsemium elegans. To confirm their structures, the chemical transformation of a humantenine-type alkaloid into gelsevanillidine (1) and the deacetoxy derivative of gelseoxazolidinine was performed.     

Fourier transform infrared spectroscopic approach to the study of the secondary cell wall development in cotton fiber

Cotton fiber maturity is a major yield component and an important fiber quality trait that is directly linked to the quantity of cellulose deposited during the secondary cell wall (SCW) biogenesis. Cotton fiber development consists of five major overlapping stages: differentiation, initiation, polar elongation, secondary cell wall development, and maturation. The transition period between 16 and 21 dpa (days post anthesis) is regarded to represent a major developmental stage between the primary cell wall and the SCW. Fourier Transform Infrared spectroscopy was used to investigate the structural changes that occur during the different developmental stages. The IR spectra of fibers harvested at different stages of development (10, 14, 17, 18, 19, 20, 21, 24, 27, 30, 36, 46, and 56 dpa) show the presence of vibrations located at 1,733 cm⁻¹ (C=O stretching originating from esters or amides) and 1,534 cm⁻¹ (NH₂ deformation corresponding to proteins or amino acids). The results converge towards the conclusion that the transition phase between the primary cell wall and the secondary cell wall occurs between 17 and 18 dpa in fibers from TX19 cultivar, while this transition occurs between 21 and 24 dpa in fibers from TX55 cultivar.     

Total reflection X-ray fluorescence analyses of samples from oil refining and chemical industries

The applicability and performance of the TXRF method for the analysis of sample materials from the oil refining and chemical industries were studied. One objective of the study was to develop rapid analytical procedures for the determination of elements present as traces in size fractionated diesel emission particles, in raw materials of resin production (ureas and phenols) and in trouble-shooting samples. Another goal was to determine the real, rather than the ideal, detection limits for the various applications. Absolute detection limits for most elements found in size fractionated diesel emission particles were below 1 ng. Relative detection limits determined for trace elements in ureas were between 5 and 30 μg kg⁻¹. Only the values for P, S and Ca exceeded this range. Additionally, remarkable differences in trace elements below 1 mg kg⁻¹ could be detected between five commercial ureas. © 1997 Elsevier Science B.V.     

Thermal behavior of corn fibers and corn fiber gums prepared in fiber processing to ethanol

In this work, a thorough study of all solid products obtained in corn fiber processing to ethanol has been carried out with thermogravimetry/mass spectrometry (TG/MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The thermal behavior of corn fiber, destarched corn fiber, various alkali pretreated fibers and corn fiber gums were compared.It has been established that no significant changes occur in the thermal behavior of the feedstock material as a result of treatment with amylolytic enzymes. On one hand only the concentration of the alkali (NaOH or KOH) seems to be important in determining the chemical composition of the pretreated corn fiber samples. On the other hand, the composition of the corn fiber gums depends on the type and not the concentration of the alkali used in the pretreatment step. The presence of H₂O₂ degrades the structure and alters the composition of the corn fiber to a larger extent. The polymeric hemicellulose which is precipitated after pretreatment with NaOH + H₂O₂ contains less impurities than the corn fiber gum prepared in the absence of hydrogen peroxide.The results indicate that the applied analytical methods are suitable for studying changes in the composition of the variously treated corn fibers. The observed effects of the treatments are in good agreement with data determined with conventional analytical techniques.     

Physicochemical and thermal properties of lignocellulosic fiber from sugar palm fibers: effect of treatment

Sugar palm fiber (SPF) is one of the prospective fibers used to reinforce polymer composites. The aim of this study is to evaluate the physicochemical, thermal, and morphological properties of SPF after alkali and sea water treatments. The chemical constituents group and thermal stability of the SPF were determined using scanning electronic microscopy (SEM) along with energy dispersive X-ray spectroscopy and thermogravimetric analysis (TGA). Fourier transform infrared spectroscopy was carried out to detect the presence of functional groups in untreated and treated SPF. The SEM images after both treatments showed that the external surface of the fiber became clean as a result. However, the sea water treatment affected the fiber properties physically, while the alkali treatment affected it both physically and chemically by dissolving the hemicellulose in the fiber. The TGA results showed that untreated fiber is significantly more stable than treated fiber. In conclusion, the results show that the fiber surface treatment significantly affected the characterization of the fiber.     

Electrostatic control of thickness and stiffness in a designed protein fiber

Attempts to design peptide-based fibers from first principles test our understanding of protein folding and assembly, and potentially provide routes to new biomaterials. Several groups have presented such designs based on alpha-helical and beta-strand building blocks. A key issue is this area now is engineering and controlling fiber morphology and related properties. Previously, we have reported the design and characterization of a self-assembling peptide fiber (SAF) system based on alpha-helical coiled-coil building blocks. With preceding designs, the SAFs are thickened, highly ordered structures in which many coiled coils are tightly bundled. As a result, the fibers behave as rigid rods. Here we report successful attempts to design new fibers that are thinner and more flexible by further programming at the amino-acid sequence level. This was done by introducing extended, or "smeared", electrostatic networks of arginine and glutamate residues to the surfaces of the coiled-coil building blocks. Furthermore, using arginine--rather than lysine--in these networks plays a major role in the fiber assembly, presumably by facilitating multidentate intra and intercoiled-coil salt bridges.     

朱砂玉兰及其变种辛夷挥发油的化学成分比较分析

为了了解不同品种辛夷挥发油的化学成分的差异,用水蒸气蒸馏法提取了朱砂玉兰及其两个变种的辛夷挥发油,并对其化学成分进行了GS/MS分析.从三种淡黄色芳香性的挥发油中共检测出44种组分,其中朱砂玉兰的成分较为简单,主要药物活性成分桉油精(17.72%)和香料成分(58.26%)的含量均较高;萼朱砂玉兰的桉油精含量较低,但香料成分(62.66%)的含量较高;而红运朱砂玉兰的桉油精含量最高,并含有较多的特有成分.朱砂玉兰不同品种的辛夷挥发油的化学组成及化合物的百分含量存有较大差异,但均含有多种药用或香料成分,具有开发利用价值;而朱砂玉兰及其变种的辛夷挥发油自身特有的化学组成,也可为玉兰属植物的化学分类研究提供有用的信息.     

Adsorption properties of activated carbon from waste newspaper prepared by chemical and physical activation

Adsorption properties of activated carbons prepared from waste newspaper by chemical and physical activation were investigated using water vapor, ammonia, methane, and methylene blue (MB) as adsorbents. The water vapor adsorption isotherms show type V behavior and the maximum vapor adsorption of the chemically and physically activated products is about 1050 and 450 ml/g, respectively. The higher water vapor adsorption of the chemically activated products is attributed to the higher specific surface area (S(BET)) and greater hydrophilic activity (arising from the surface oxygen-containing functional groups) than in the physically activated products. The adsorption of ammonia and methane was measured by temperature-programmed desorption (TPD). NH(3) adsorption is found to be higher in the chemically activated product than in the physically activated product while methane adsorption is slightly higher in the physically activated products even though these have lower S(BET) values. In the MB adsorption, the chemically activated products show higher adsorption (390 mg/g) than the physically activated product. These results are suggested to be related to the surface characteristics.     

Sorption properties of activated carbons obtained from corn cobs by chemical and physical activation

The paper presents results of a study on obtaining activated carbon from common corn cobs and on its use as adsorbent for removal of pollution from liquid and gas phases. The crushed precursor was subjected to pyrolysis at 500 and 800?°C in argon atmosphere and next to physical or chemical activation by CO₂ and KOH respectively. The effect of pyrolysis conditions and activation method on the physicochemical properties of the materials obtained was tested. The sorption properties of the carbonaceous adsorbents obtained were characterized by determination of nitrogen dioxide and hydrogen sulphide sorption from gas stream in dry and wet conditions as well as by iodine and methylene blue removal from aqueous solution. The final products were microporous activated carbons of well-developed surface area varying from 337 to 1213 m²/g and showing diverse acid-base character of the surface. The results obtained in our study have proved that a suitable choice of the activation procedure for corn cobs permits production of cheap adsorbents with high sorption capacity toward toxic gases of acidic character as well as different pollutants from liquid phase.     

Porous properties of activated carbons from waste newspaper prepared by chemical and physical activation

Activated carbons were prepared from old newspaper and paper prepared from simulated paper sludge by chemical activation using various alkali carbonates and hydroxides as activating reagents and also by physical activation using steam. In the chemical activation, the influence of oxidation, carbonization, and activation on the porous properties of the resulting activated carbons was investigated. The specific surface areas (S(BET)) of the activated carbons prepared by single-step activation (direct activation without oxidation and carbonization) were higher than those resulting from two-step activation (oxidation-activation and carbonization-activation) and three-step activation (oxidation-carbonization-activation) methods. The S(BET) values were strongly dependent on the activating reagents and the activating conditions, being >1000 m(2)/g using K(2)CO(3), Rb(2)CO(3), Cs(2)CO(3), and KOH as activating reagents but <1000 m(2)/g using Li(2)CO(3), Na(2)CO(3), and NaOH. These differences in S(BET) values are suggested to be related to the ionic radii of the alkalis used as activating reagents. The microstructures of the higher S(BET) samples show a complete loss of fiber shape but those of the lower S(BET) samples maintain the shape. In the physical activation, the porous properties of the activated carbons prepared by the single-step method were examined as a function of the production conditions such as activation temperature, activation time, steam concentration, and flow rate of the carrier gas. The maximum S(BET) and total pore volume (V(P)) were 1086 m(2)/g and 1.01 ml/g, obtained by activation at 850 degrees C for 2 h, flowing 20 mol% of steam in nitrogen gas at 0.5 l/min. A correlation was found between S(BET) and the yield of the product, the maximum S(BET) value corresponding to a product yield of about 10%. This result is suggested to result from competition between pore formation and surface erosion. Compared with chemically activated carbons using K(2)CO(3), the porous properties of the physically activated carbons have lower S(BET) and V(P) values because of the smaller size and lower volume of their micropores. On the other hand, they retain the original fiber shape and the paper sheet morphology after activation.