化控对砂糖橘成花数和磷素的影响及相关性分析

通过盆栽试验研究干旱胁迫与不同化控技术(多效唑、核苷酸)结合对砂糖橘抽发新梢数、成花数、叶中磷素含量及其关系的影响.结果表明:与对照相比,化控处理均显著抑制砂糖橘抽发的新梢数,但化控处理间差异不显著;与对照相比,化控处理均能诱导砂糖橘成花,但多效唑+干旱胁迫处理(PDSN0)和多效唑+干旱胁迫+50 mg/L核苷酸处理(PDSN1)成花数差异不显著,而多效唑+干旱胁迫+100 mg/L核苷酸处理(PDSN2)成花数显著小于其它化控处理.叶中磷素含量主要受叶片中磷素含量的制约;在处理前期,除个别处理外,所有化控处理叶中磷素含量均降低,但同一时间内化控处理间差异不显著;在处理后期,多效唑+干旱胁迫和两种浓度的核苷酸在影响叶中磷素含量方面效果相反;在开花前期,各处理叶中磷素含量分别比处理前增加46.15%、30.77%、23.08%和30.77%;在化控处理前期、中期、后期和开花前期,叶中磷索含量与成花数呈显著或极显著负相关.     

Influence of noncellulosic contents on nano scale refinement of waste jute fibers for reinforcement in polylactic acid films

In the present study, nanofibrils of cellulose are extracted from waste jute fibers using high energy planetary ball milling process in wet condition. The rate of refinement of untreated fibers having non-cellulosic contents was found slower than treated fibers due to strong holding of fiber bundles by non-cellulosic contents. At the end of three hours of wet milling, untreated fibers were refined to the size of 850 nm and treated fibers were refined to the size of 443 nm. In the subsequent stage, composite films of poly lactic acid (PLA) were prepared by solvent casting with 3 wt% loading of untreated jute nanofibrils, treated jute nanofibrils and microcrystalline cellulose. The influence of non-cellulosic contents on mechanical properties of PLA films are investigated based on results of tensile test, dynamic mechanical analysis and differential scanning calorimetry. The maximum improvement was observed in case of treated jute nanofibril/PLA composite film where initial modulus and tensile strength increased by 207.69 % and 168.67 %, respectively as compared to neat PLA film. These improvements are attributed to the increased interaction of treated jute nanofibrils with PLA matrix due to their higher precentage of cellulosic contents and mechanically activated surface.     

Highly Dispersible Cellulose Nanofibrils Produced via Mechanical Pretreatment and TEMPO-mediated Oxidation

Cellulose nanofibrils (CNFs) can prepare flexible nanomaterials with its large aspect ratio. Due to the supramolecular, cellulose fibers are difficultly dissociated to CNFs. In order to destroy this supramolecular structure and prepare high dispersible CNFs, the mechanical and chemical treatments are required. This study examined the effects of mechanical pretreatment and TEMPO-oxidation on the properties of CNFs preparing from bleached softwood kraft pulp. The total yield of TEMPO-oxidized cellulose nanofibrils (TOCNFs) reached 85 %. The morphology, carboxyl group content, crystallinity, surface charge, self-assembling properties, and optical transmittance of the corresponding TOCNFs suspension were investigated. The transmittance of TOCNFs suspension was 95.1 % at 600 nm wavelength and its corresponding ζ- potential was -61.3 mV, indicated that the strong electrostatic repulsion between TOCNFs was the most significant factor on the highly transparent TOCNFs suspension in water. Furthermore, the mostly negative charged TOCNFs obtained by freeze drying assembled into the finest and most uniform networked structure. Such highly transparent, functionalized, selfassembled cellulose nanofibrils are favorable in transparent films, flexible displays and electrochemistry materials.     

Effect of alkali and silane treatments on mechanical and thermal behavior of Phormium tenax fibers

The effect of different treatments on the mechanical (tensile), thermal behavior (TGA), FTIR, and morphology of Phormium tenax fibers has been studied with the aim to investigate methods to improve their compatibility with polymer matrices. Applied treatments included sodium hydroxide (NaOH), silane (APTES, 3-aminopropyltriethoxysilane), and the combined application of silane treatment after NaOH. The effectiveness of the treatments in the removal of non-structural matter from the fibers was confirmed by FTIR investigation and TGA measurements, suggesting also that the alkali treatment has a strong effect on their thermal behavior. The study of tensile properties of the fibers performed using Weibull statistics indicates that the tensile properties are somewhat reduced by chemical treatment. The morphological investigation of treated fibers through scanning electron microscopy indicates that silane treatments, both on raw fibers and on alkalized ones, result in limited fiber degradation.     

不同药剂处理对月季种子脱落酸含量的影响

以月季(Rosa chinensis)种子为研究对象,研究了不同药剂处理对月季种子脱落酸含量的影响。试验结果表明:纤维素酶处理后种子脱落酸含量低于浓硫酸和赤霉素处理后的种子脱落酸含量,利用纤维素酶处理可以有效降低种子的脱落酸含量。     

High-intensity ultrasound irradiated modification of sugarcane bagasse cellulose in an ionic liquid

This current work is concerned with the glutarylation of sugarcane bagasse cellulose in ionic liquid 1-butyl-3-methylimidazolium chloride by ultrasound irradiation without catalyst. The degree of substitution ranging from 0.22 to 1.20 was obtained in one-step homogeneous modification, which increased with ultrasound irradiation time, temperature, and the molar ratio of glutaric anhydride/anhydroglucose unit in cellulose. The structural characterization of the glutarylated cellulose was carried out by using FT-IR and CP/MAS ¹³C NMR and the results showed that the glutarylation reaction occurred. The thermal stability of the glutarylated cellulose decreased upon chemical modification.     

Effects of thermal treatment on durability of short bamboo-fibers and its reinforced composites

This study was performed to investigate the influence of heat treatment on the chemical transformation and associated improved durability of short bamboo-fibers (BF) and its reinforced composites. Results showed that cleavage of acetyl groups of the hemicelluloses developed with increasing temperature and holding time, and completed beyond 190 °C for more than 3 h, resulting in a noticeable increase of cellulose content and a substantial reduction of concentration of accessible hydroxyl groups. Heat treatment improved thermal stability and anti-UV aging properties of treated BF, and also contributed to a decrease of equilibrium moisture content (EMC) of treated BF and consequent improvements of hygroscopicity and the dimensional stability of its reinforced composite. However, immoderate heat treatment for BF wasn’t in favor of improvements of hygroscopicity and the dimensional stability of BF based composites.     

Extraction, preparation and characterization of cellulose fibres and nanocrystals from rice husk

Cellulose fibres and cellulose nanocrystals were extracted from rice husk. Fibres were obtained by submitting the industrial rice crop to alkali (NaOH) and bleaching treatments. Nanocrystals were extracted from these fibres using sulphuric acid (H₂SO₄) hydrolysis treatment. The material obtained after each stage of the treatments was carefully characterized and its chemical composition was determined. Morphological investigation was performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectroscopy showed the progressive removal of non-cellulosic constituents. X-ray diffraction (XRD) analysis revealed that the crystallinity increased with successive treatments. The thermal stability of the rice husk fibres and cellulose nanocrystals was also investigated using thermogravimetric analysis (TGA).     

Low-temperature pyrolysis on jute fibers as a thermochemical modification method

Low-temperature pyrolysis up to 200, 250, 300 °C was conducted in order to remove non-cellulosic compounds without damaging the structure of the cellulose in jute fibers. The chemical, morphological, and mechanical aspects of prepared low-temperature pyrolyzed jute fibers were investigated by Fourier transform infrared (FTIR) spectroscopy, the wettability test in water/dichloromethane system, moisture content measurement, X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), and tensile test using universal testing machine (UTM). It was confirmed that hydrophilic compounds including absorbed water, low molecular weight compounds such as waxes, hemicellulose, and lignin were largely removed from the fibers. Increasing amounts of non-cellulosic compounds were removed as the maximum pyrolysis temperature was increased. The degree of hydrophilic nature of jute fibers were reduced by low-temperature pyrolysis and thus water absorptivity of pyrolyzed jute fibers was reduced as maximum pyrolysis temperature increased. Furthermore, XRD analysis and morphological studies by SEM indicated that the crystalline structure of native cellulose was rarely damaged after pyrolysis up to 300 °C. In case of mechanical properties, breaking tenacity and breaking strain of the fibers decreased with increasing maximum pyrolysis temperatures because flaws formed on the surface of pyrolyzed jute fibers acted as weak-links. In agreement with predictions made according to Weibull’s weakest-link theory, it was found that shortened pyrolyzed jute fibers could have higher breaking tenacities compared with raw jute fibers of the same length. In addition, the compatibility with hydrophobic matrix was investigated by the mechanical properties of polypropylene (PP) reinforced with jute fibers. Consequently, it was hypothesized that low-temperature pyrolysis could be used to process raw jute fibers for use as short fiber reinforcements in fiber-polymer systems or be a simple and effective pretreatment method for a wide range of further chemical treatments.     

Oil palm fiber (OPF) and its composites: A review

Twenty first century has witnessed remarkable achievements in green technology in material science through the development of biocomposites. Oil palm fiber (OPF) extracted from the empty fruit bunches is proven as a good raw material for biocomposites. The cellulose content of OPF is in the range of 43%–65% and lignin content is in the range of 13%–25%. A compilation of the morphology, chemical constituents and properties of OPF as reported by various researchers are collected and presented in this paper. The suitability of OPF in various polymeric matrices such as natural rubber, polypropylene, polyvinyl chloride, phenol formaldehyde, polyurethane, epoxy, polyester, etc. to form biocomposites as reported by various researchers in the recent past is compiled. The properties of these composites viz., physical, mechanical, water sorption, thermal, degradation, electrical properties, etc. are summerised. Oil palm fiber loading in some polymeric matrices improved the strength of the resulting composites whereas less strength was observed in some cases. The composites became more hydrophilic upon addition of OPF. However treatments on fiber surface improved the composite properties. Alkali treatment on OPF is preferred for improving the fiber–matrix adhesion compared to other treatments. The effect of various treatments on the properties of OPF and that of resulting composites reported by various researchers is compiled in this paper. The thermal stability, dielectric constant, electrical conductivity, etc. of the composites improved upon incorporation of OPF. The strength properties reduced upon weathering/degradation. Sisal fiber was reported as a good combination with OPF in hybrid composites.     

施肥对黑土玉米田土壤中纤维素分解菌数量的影响

利用长期定位试验和室内分析相结合的方法,对玉米不同生育期内表层土壤(0~20 cm)和亚表层土壤(21~40 cm)中纤维素分解菌数量以及好气和嫌气性纤维素分解菌数量进行分析测定。结果表明,在玉米生长的同一时期,不同施肥方式下(除休闲处理),表层和亚表层土壤的纤维素分解菌数量和好气性纤维素分解菌数量表现出类似的规律性,即有机无机肥料配施处理单施化肥处理不施肥处理;对于土壤嫌气性纤维素分解菌数量,不同施肥方式对表层土壤没有明显的规律性,亚表层土壤中除拔节期外为有机无机肥料配施处理单施化肥处理不施肥处理。休闲处理的微生物数量均大于不施肥处理。     

不同处理对黄麻纤维木质素去除及织物性能的影响

本文研究了草酸铵、漆酶以及木聚糖酶单独或联合处理对黄麻机织布中木质素的去除作用及对织物褶皱、力学性能的影响。结果表明,漆酶单一处理仅能去除少量的木质素,联合处理可提高木质素的去除效率,以草酸铵、木聚糖酶、漆酶联合处理效果最好。在ATR红外谱图中,草酸铵、木聚糖酶、漆酶联合处理后的黄麻机织布较未处理织物在1594 cm-1、1506cm-1和1424 cm-1处的木质素芳香族特征吸收峰,1731 cm-1和1646 cm-1处的木质素羰基特征吸收峰及1242 cm-1-1031 cm-1处的半纤维素醚键特征吸收峰均有减弱,说明经草酸铵、木聚糖酶、漆酶联合处理后黄麻纤维表面木质素和半纤维素含量降低。经处理后黄麻机织布褶皱回复角提高,其中草酸铵、木聚糖酶、漆酶联合处理褶皱回复性最佳。漆酶单独处理后黄麻机织布断裂强力和断裂延伸率均提高,联合处理后断裂强力降低,断裂延伸率提高。     

Preparation process and antimicrobial properties of cross-linking chitosan onto periodate-oxidized bamboo pulp fabric

Chitosan cross-linked bamboo pulp fabric (CCBPF) was prepared by treating the oxidized bamboo pulp fabric with the chitosan aqueous acetic acid solution. FTIR spectroscopy was used to examine the chemical bonding between chitosan and oxidized bamboo pulp fabrics, X-ray diffraction and thermogravimetry were used to detect the cellulose structure. The impact of the periodate oxidation and chitosan treatment on the physical properties of bamboo pulp fabrics was evaluated by determining the aldehyde content, weight loss, mechanical strength, wrinkle recovery angle, and moisture regain of fabrics as well as chitosan content in the composite chitosan-bamboo pulp fabrics. Antibacterial activity of the CCBPF against Staphylococcus aureus and Escherichia coli was investigated in vitro experiments. The results indicated that the aldehyde groups in the periodate oxidized bamboo pulp cellulose were reacted with the amino groups of chitosan to form Schiff base, and the resultant CCBPF displayed good wrinkle recovery angle and moisture regain. In comparison with those of the oxidized bamboo pulp fabric, the CCBPF exhibited a lower thermal stability, the crystallinity decreased from 42.73 % to 39.15 %, the mechanical strength of CCBPF had no significant change, and the CCBPF showed excellent antibacterial activity against both types of bacteria which was durable till 50 washes.     

Preparation and characterization of cellulose nanofiber reinforced thermoplastic starch composites

In the present study, cellulose nanofibers composite films were manufactured based on thermoplastic starch. Nanofibers were extracted from rice straw employing a developed chemo-mechanical method. In the chemical step, almost all of non-cellulosic components were removed and a white pulp of cellulose microfibers was obtained. Then, a diluted suspension of fibers was ultrasonicated to destruct intermolecular hydrogen bonds achieving nanofibers networks. Afterward, bio-nanocomposites were prepared by film casting. In order to study the effect of nanofibers content on the composite properties, the mechanical and dynamic mechanical properties, morphology, humidity absorption, and transparency of films were investigated. The yield strength and Young modulus of nanocomposites were satisfactorily enhanced compared to the pure thermoplastic starch film. The glass transition temperature of films was shifted to higher temperatures by increasing nanofibers contents. The uniform dispersion of the nanofibers was investigated using SEM images. The humidity absorption resistance of films was significantly enhanced by using 10 wt% cellulose nanofibers. The transparency of the nanocomposites was reduced compared to the pure starch films.     

Jute yarn as reinforcement for polypropylene based commingled eco-composites: Effect of fibre content and chemical modifications on accelerated ageing and tear properties

Bidirectional PP/jute yarn eco-composites were fabricated via environment friendly commingling technique and its long term durability/life time was monitored as an effect of accelerated solar ageing on its mechanical properties (tensile & flexural). Accelerated solar ageing promoted the thermal oxidation of PP thus resulting in deterioration of its properties, however; MAPP and KMnO₄ treated commingled composites showed much better stability towards thermal oxidation brought about by the solar concentrator, compared to untreated sample and neat polypropylene. This increased resistivity of treated composites (especially MAPP and KMnO₄) towards thermal oxidation brought about by the solar concentrator is due to the increased interfacial adhesion between the matrix and jute yarn owing to chemical modifications. The significance of effective stress transfer between the PP matrix and reinforcing jute yarns is evident from the increased tear resistance of PP/jute yarn commingled composites with increasing fibre content and also with different chemical treatments.     

Effects of surface treatment of ramie fibers in a ramie/poly(lactic acid) composite

The chemical and morphological properties of ramie fibers treated by chemical surface modification were examined with Fourier transform infrared (FT-IR) spectroscopy. The mechanical and thermal decomposition properties were evaluated with respect to tensile strength, tensile modulus and thermogravimetric analysis (TGA). Surface morphological changes were investigated with scanning electron microscopy (SEM). Finally, the capabilities of composites reinforced with various chemically treated fibers were analyzed by investigating tensile and impact strengths. Additionally, the thermal mechanical properties of the composites were investigated with thermal mechanical analysis (TMA). Based on the results of these analyses, we concluded that pectin, lignin and hemicellulose were removed and thermal stability was increased with chemical treatments. The composites reinforced with ramie fiber showed better properties compared with pure PLA matrix with respect to tensile and impact strengths. The peroxide-treated fiber composite had the smallest thermal expansion.     

Release of doxycycline through cellulose acetate symmetric and asymmetric membranes produced from recycled agroindustrial residue: Sugarcane bagasse

Cellulose acetate is one of the components employed in drug controlled-release systems in the form of membranes. The aim of this study was to examine the controlled-release of doxycycline employing cellulose acetate symmetric and asymmetric membranes as matrices. The cellulose triacetate was produced from sugarcane bagasse through a homogeneous acetylation reaction, using acetic acid as the solvent, acetic anhydride as the acetylating agent and sulfuric acid as the catalyst. The viscosity average molecular weight of the cellulose acetate produced was 39,000 g mol⁻¹. The symmetric membranes were produced using a system solvent of dichloromethane/ethanol (9:1, v/v) and the asymmetric membranes were produced from the same solvent system and 10% of water. For the formulation of both, 5% of doxycycline was used. The membranes were characterized by thermal analysis (DSC and TGA) and scanning electron microscopy SEM. The release of doxycycline through cellulose triacetate matrices was examined using spectrophotometric analysis in the ultraviolet-visible region, at 275 nm. The results revealed that asymmetric membranes release 80% of the drug in 100 min, while symmetric membranes release 14% of the drug during the same time interval.     

酸性电解水结合复合膜对橘柚保鲜效果的研究

为了防止橘柚采后枯水腐烂,采用酸性电解水浸果处理,并结合海藻酸钠、羧甲基纤维素钠、茶多酚、抗坏血酸配制成的复合保鲜剂进行涂膜处理后,将橘柚果实置于温度为 (8±1)℃、湿度为75%~80%的条件下存放120 d,以好果率、失重率、细胞膜透性、可滴定酸度、可溶性固形物以及类胡萝卜素为指标进行保鲜效果的评价,通过正交试验确定最佳保鲜方法。本研究所用的复合膜是多孔网络结构的薄膜,空隙小而细腻、均匀分散,复合膜处理后的果皮表面平整光滑,断面结构致密,在果实表面形成屏障。结果表明：酸性电解水处理能有效控制橘柚果实采后病害的发生,复合膜处理可以较好地控制橘柚的腐烂和失水现象,延缓果实衰老,有效保持可滴定酸和可溶性固形物的含量,还能提高果皮色泽;正交试验优化得出最优的保鲜方法,以有效氯含量为30 mg/L的酸性电解水浸果15 min,并联合海藻酸钠0.5%、羧甲基纤维素钠0.5%、茶多酚2.0%、抗坏血酸1.0%配比组合下的复合保鲜剂涂膜20 min。因此认为,酸性电解水结合复合膜处理能提高采后橘柚的品质、延长果实保鲜期。     

Termite resistance of biobased composition boards made from cotton byproducts and guayule bagasse

Large quantities of cotton gin byproducts (CGB), also known as cotton gin trash or cotton gin waste, are being produced across the cotton belt of the United States annually. Similarly, guayule wastes after rubber latex production is expected to increase as this industry begins to expand. Use of these waste materials in value-added products can help the economics of the crops and aid in alleviating waste management issues and environmental problems. Conventional wood preservatives used to protect wood from insect and microbial damage are of concern to human health and the environment. Guayule bagasse (GB) has been shown to have termite control properties, and a combination of cotton gin and guayule wastes could also have such valuable properties. An initial study evaluating the physical and mechanical properties of boards produced from these two biomasses was published in 2009, this study is a continuation focusing on the termite resistance of boards produced. Thus, the objective of this research was to determine the termite resistance property of experimental composition boards made from CGB and GB. Composition boards were made from five different ratios of CGB to GB: 100:0, 75:25, 50:50, 25:75 and 0:100 (C100, C75-G25, C50-G50, C25-G75, and G100, respectively). Additionally, three-layered boards (3-layer) consisting of 25% GB (upper layer), 50% CGB (middle layer), and 25% GB (bottom layer) were made. For comparison, a commercial southern pine lumber board (SPB), a commercial oriented strandboard (OSB), and a commercial preservative treated medium density fiberboard (MDF) were included in the testing. This testing was an extension of a previous study where the mechanical properties of the CGB and GB composition boards were compared to select commercial standards. Five specimens were cut from each of the nine different board treatments and tested using Eastern subterranean termites. Weight loss, termite survival days, and visual grade of each specimen were determined according to testing standards. Results confirmed good termite control quality for boards made from GB alone. Boards containing CGB to GB ratios of 75-25 and 50-50 obtained similar termite resistance as the commercial OSB based on the total weight loss and one-week termite mortality rate. Visual grading of tested specimens revealed all six CGB and GB composition boards and the treated MDF showed better rating than the commercial OSB and pine lumber. No differences were noted among the total termite surviving days for the six CGB and GB composition boards. Overall, the biobased CGB and GB boards showed promise with the boards containing GB exhibiting improved termite resistance properties than SPB and OSB.     

Sugarcane bagasse whiskers: Extraction and characterizations

This work evaluates the use of sugarcane bagasse (SCB) as a source of cellulose to obtain whiskers. These fibers were extracted after SCB underwent alkaline peroxide pre-treatment followed by acid hydrolysis at 45 °C. The influence of extraction time (30 and 75 min) on the properties of the nanofibers was investigated. Sugarcane bagasse whiskers (SCBW) were analyzed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) in air atmosphere. The results showed that SCB could be used as source to obtain cellulose whiskers and they had needle-like structures with an average length (L) of 255 ± 55 nm and diameter (D) of 4 ± 2 nm, giving an aspect ratio (L/D) around 64. More drastic hydrolysis conditions (75 min) resulted in less thermally stable whiskers and caused some damage on the crystal structure of the cellulose as observed by XRD analysis.