Effects of cellulose nanofibrils treatment on antioxidant properties and aroma of fresh-cut apples.

Horticultural products tend to deteriorate during postharvest storage and processing. In this study, cellulose nanofibers (CNFs) were prepared from wood to investigate the effects of CNF treatment on the storage quality, aroma composition, and antioxidant system of fresh-cut apple (Malus domestica) wedges. Compared with control treatment, CNF coating treatment significantly improved the appearance of apple wedges; reduced the decay rate of apple wedges; and delayed the decline in weight loss, firmness, and titratable acid during storage. Gas chromatography-mass spectrometry showed that CNF treatment could maintain the aroma components of apple wedges (stored for 4 days). Further investigations showed that CNF treatment increased the antioxidant system level and decreased reactive oxygen species content and membrane lipid peroxidation level of apple wedges. Overall, this study showed that CNF coating could effectively maintain the quality of fresh-cut apples during cold storage.

Exploring Supramolecular Interactions between the Extracellular-Matrix-Derived Minimalist Bioactive Peptide and Nanofibrillar Cellulose for the Development of an Advanced Biomolecular Scaffold.

It has been increasingly evident over the last few years that bioactive peptide hydrogels in conjugation with polymer hydrogels are emerging as a new class of supramolecular materials suitable for various biomedical applications owing to their specificity, tunability, and nontoxicity toward the biological system. Despite their unique biocompatible features, both polymer- and peptide-based scaffolds suffer from certain limitations, which restrict their use toward developing efficient matrices for controlling cellular behavior. The peptide hydrogels usually form soft matrices with low mechanical strength, whereas most of the polymer hydrogels lack biofunctionality. In this direction, combining polymers with peptides to develop a conjugate hydrogel can be explored as an emergent approach to overcome the limitations of the individual components. The polymer will provide high mechanical strength, whereas the biofunctionality of the material can be induced by the bioactive peptide sequence. In this study, we utilized TEMPO-oxidized nanofibrillar cellulose as the polymer counterpart, which was co-assembled with a short N-cadherin mimetic bioactive peptide sequence, Nap-HAVDI, to fabricate an NFC-peptide conjugate hydrogel. Interestingly, the mechanical strength of the peptide hydrogel was found to be significantly improved by combining the peptide with the NFC in the conjugate hydrogel. The addition of the peptide into the NFC also reduced the pore size within NFC matrices, which further helped in improving cellular adhesion, survival, and proliferation. Furthermore, the cells grown on the NFC and NFC-peptide hybrid hydrogel demonstrated normal expression of cytoskeleton proteins, i.e., ß-tubulin in C6 cells and actin in L929 cells, respectively. The selective response of neuronal cells toward the specific bioactive peptide was further observed through a protein expression study. Thus, our study demonstrated the collective role of the cellulose-peptide composite material that revealed superior physical properties and biological response of this composite scaffold, which may open up a new platform for biomedical applications.

Valorisation of fruit peel bioactive into green synthesized silver nanoparticles to modify cellulose wrapper for shelf-life extension of packaged bread.

Fruit peels are rich source of bioactive compounds such as polyphenols, flavonoids, and antioxidants but are often discarded as waste due to limited pharmaceutical and nutraceutical applications. This study aimed to valorise pomegranate and citrus fruit peel into green synthesised silver nanoparticles (AgNPs) in order to modify cellulose-based wrapping material for prospective food packaging applications and propose an alternate and sustainable approach to replace polyethene based food packaging material. Four different concentrations of AgNO3 (0.5 mM, 1 mM, 2 mM, and 3 mM) were used for green synthesis of AgNPs from fruit peel bioactive, which were characterised followed by phytochemical analysis. Ultraviolet-Visible spectroscopy showed surface plasmon resonance at 420 nm, XRD analysis showed 2θ peak at 27.8°, 32.16°, 38.5°, 44.31°, 46.09°, 54.76°, 57.47°, 64.61° and 77.50° corresponding to (210), (122), (111), (200), (231), (142), (241), (220) and (311) plane of face centred cubic crystal structure of AgNPs. Fourier-transform infrared spectroscopy analysis of AgNPs green synthesised from pomegranate and kinnow peel extract showed a major peak at 3277, 1640 and 1250-1020 1/cm while a small peak at 2786 1/cm was observed in case of pomegranate peel extract which was negligible in AgNPs synthesized from kinnow peel extract. Particle sizes of AgNPs showed no statistically significant variance with p > 0.10 and thus, 2 mM was chosen for further experimentation and modification of cellulose based packaging material as it showed smallest average particle size. Zeta potential was observed to be nearly neutral with a partial negative strength due to presence of various phenolic compounds such as presence of gallic acid which was confirmed by ultrahigh performance liquid chromatography-photodiode array(UHPLC-PDA) detector. Thermal stability analysis of green synthesised AgNPs qualified the sterilisation conditions up to 100 °C. AgNPs green synthesized from both the peel extracts had higher polyphenolic content, antioxidant and radical scavenging activity as compared to peel extracts without treatment (p < 0.05). The cellulose based food grade packaging material was enrobed by green synthesised AgNPs. The characterisation of modified cellulose wrappers showed no significant difference in thickness of modified cellulose wrappers as compared with untreated cellulose wrapper (p > 0.42) while weight and grammage increased significantly in modified cellulose wrapper (p < 0.05). The colour values on CIE scale (L*, a* and b*) showed statistically significant increase in yellow and green colour (p < 0.05) for modified cellulose wrappers as compared to control wrapper. The oxygen permeability coefficient, water vapour permeability coefficient, water absorption capacity and water behaviour characteristics (water content, swelling degree and solubility) showed significant decrease (p < 0.05) for modified cellulose wrapper as compared to control wrapper. A uniform distribution and density of green synthesised AgNPs across cellulose wrapper matrix was observed through scanning electron microscopy (SEM) images with no significant aggregation, confirming successful enrobing and stable immobilisation of nanoparticles from cellulose matrix. A seven-day storage study of bread wrapped in modified and control cellulose wrappers showed delayed occurrence of microbial, yeast and mould count in bread packaged in modified cellulose wrappers and thus, resulting in shelf life extension of bread. The results are encouraging for the potential applications of modified cellulose wrappers to replace polyethene based food packaging.

Progress in high-resolution isotope-ratio analysis of tree rings using laser ablation.

Stable isotope ratio analysis of tree rings has been widely and successfully applied in recent decades for climatic and environmental reconstructions. These studies were mostly conducted at an annual resolution, considering one measurement per tree ring, often focusing on latewood. However, much more information could be retrieved with high-resolution intra-annual isotope studies, based on the fact that the wood cells and the corresponding organic matter are continuously laid down during the growing season. Such studies are still relatively rare, but have a unique potential for reconstructing seasonal climate variations or short-term changes in physiological plant properties, like water-use efficiency. The reason for this research gap is mostly technical, as on the one hand sub-annual, manual splitting of rings is very tedious, while on the other hand automated laser ablation for high-resolution analyses is not yet well established and available. Here, we give an update on the current status of laser ablation research for analysis of the carbon isotope ratio (δ13C) of wood, describe an easy-to-use laser ablation system, its operation and discuss practical issues related to tree core preparation, including cellulose extraction. The results show that routine analysis with up to 100 laser shot-derived δ13C-values daily and good precision and accuracy (ca. 0.1‰) comparable to conventional combustion in an elemental analyzer are possible. Measurements on resin-extracted wood is recommended as most efficient, but laser ablation is also possible on cellulose extracted wood pieces. Considering the straightforward sample preparation, the technique is therefore ripe for wide-spread application. With this work, we hope to stimulate future progress in the promising field of high-resolution environmental reconstruction using laser ablation.

Preparation of an efficient magnetic nano-sorbent based on modified cellulose and carboxylated carbon nano-tubes for extraction of pesticides from food and agricultural water samples before GC-FID analysis.

This paper reports the direct synthesis approach of carboxamide functionalized magnetic nano-composite named Fe3O4@SiO2-NH2@dialdehyde cellulose (DAC)@CNT-COOH as an effectual sorbent for the co-extraction of seven agricultural insecticides and herbicides from vegetable, fruit, and water samples using the magnetic dispersive micro-solid-phase extraction procedure. Under the optimized extraction conditions (sorbent amount: 18.1 mg; desorption time: 6.5 min; desorption solvent volume: 185 µL; desorption solvent: acetonitrile; extraction time: 9.5 min; pH of sample solution: 7.0, and salt content: 5.0 % w/v sodium chloride), good linearity within the range 0.5-1200 ng/mL (R2 ≥ 0.998) was achieved. Extraction efficiencies were in the range 63.4-84.1 %, the limits of detection were 0.08-1.0 ng/mL, and acceptable relative recoveries (87.6-103.8 %), and precisions were also achieved (RSDs < 6.8 %, n = 3). Ultimately, the obtained results showed that the developed method could be applied to determine trace amounts of desired analytes in various agricultural water and food samples.

Electrospun ethyl cellulose/poly caprolactone/gelatin nanofibers: The investigation of mechanical, antioxidant, and antifungal properties for food packaging.

The purpose of the present research was to fabricate ethylcellulose (ECL)/polycaprolactone (PCL)/gelatin (GEL) electrospun nanofibers containing Zataria multiflora essential oil (ZEO) and zinc oxide nanoparticle (ZnO) to provide an appropriate substrate for food packaging. The ECL/PCL/GEL was incorporated with ZEO and ZnO at the concentrations of 10, 20, 30 and 50 wt% and 3 wt%, respectively. The results of ECL/PCL/GEL/ZEO/ZnO nanofiber exhibited uniform morphology with a mean diameter ranging from 361.85 ± 18.7 to 467.33 ± 14.50 nm and enhanced thermal stability. The ECL/PCL/GEL/ZEO/ZnO nanofiber had the highest mechanical parameters, such as young's modulus (437.49 ± 18), tensile strength (7.88 ± 0.7), and elongation at break (5.02 ± 0.6) and water contact angle (61.13 ± 0.5), compared with the other nanofibers. The cell viability during 48 and 72 h was obtained to be about more than 80% for all the nanofibers. Additionally, the ECL/PCL/GEL incorporated with 50% ZEO and 3% ZnO displayed the highest antioxidant activity (34.61 ± 1.98%) and antifungal properties against Penicillium notatum and Aspergillus niger. In general, the ECL/PCL/GEL with the weight ratio of 20:70:10 nanofiber incorporated with 30% ZEO and 3% ZnO was obtained to have appropriate mechanical, antioxidant, and antimicrobial properties and thermal stability.

Perennial halophyte Salicornia neei Lag.: Cell wall composition and functional properties of its biopolymers.

Salicornia neei halophyte extends in Argentina seashores. To envisage potential applications, cell wall sequential extraction performed on dry plant yielded 1.1, 2.4, 0.3 and 0.9% of pectin fractions respectively extracted by room temperature water, 90 °C-water, CDTA and Na2CO3. They contained 21-33% uronic acids (UA) with low degree of methylation and 0.5-1.2 M ratios of neutral sugars to UA. High arabinose level suggests that long arabinan side-chains maintain cell wall flexibility in water deficit. Fractions also contained 10-36% of proteins. The KOH-soluble fractions (4.3%) were mainly arabinoxylans. At 2.0% w/v, pectin fractions developed "weak gel"-type networks with Ca2+, while arabinoxylans generated "dilute solutions". Cellulose (28%) and lignin (45.1%) were the main biopolymers in the final residue, which showed low water swelling capacity (3.6 mL/g) due to lignin, increasing when arabinoxylans were also present. Phenolics (9.8%) were mainly water-extractable. Salicornia is a source of biopolymers and antioxidants potentially useful for food applications.

The Mechanism of Extraction of Peanut Protein and Oil Bodies by Enzymatic Hydrolysis of the Cell Wall.

Degradation of the peanut cell wall is a critical step in the aqueous enzymatic extraction process to extract proteins and oil bodies. Viscozyme® L, a compound cell wall degrading enzyme, has been applied as an alternative to protease in the process of aqueous enzymatic extraction, but the mechanism of cell wall enzymolysis remains unclear. The present study aims to investigate the changes in cellulose, hemicellulose, and pectin content of the peanut cell wall hydrolyzed by Viscozyme® L. The degree to which the main components of the peanut cell wall, such as trans-1, 2-cyclohexanediamine-N,N,N',N'-acetic acid-soluble pectin (CDTA-soluble pectin), Na2CO3-soluble pectin, cellulose, and hemicellulose, are degraded is closely related to the extraction of oil bodies and peanut protein at different solid-liquid ratio of powered peanut seed in distilled water, enzyme concentration, enzyme hydrolysis temperature, and enzyme hydrolysis time. The key sites of Viscozyme® L activity on cell wall polysaccharides were explored by comparing the changes in chemical bonds under different extraction conditions using Fourier-transform infrared spectroscopy (FT-IR) absorption bands and principal component analysis (PCA). Viscozyme® L acted on the C-O stretching, C-C stretching, and CH2 symmetrical bending of cellulose, the C-O stretching and O-C-O asymmetrical bending of hemicellulose, and the C-O stretching and C-C stretching of pectin.

Microcrystalline Cellulose and Crospovidone Identified in Placentas With Vaginal Misoprostol Use.

Misoprostol is a prostaglandin analog commonly used to induce termination of pregnancy. Clandestine home terminations complicate forensic fetal autopsy when a history of misoprostol use is withheld and the gross and histologic findings are sparse, as is often the case. One hundred thirty-two placentas with no vaginal misoprostol use, low-dose misoprostol use, and high-dose misoprostol use were reviewed for the presence, volume, and locations of microcrystalline cellulose and crospovidone, common tablet fillers in misoprostol tablets. Microcrystalline cellulose and/or crospovidone was identified in 0 (0%) of 88 cases with no vaginal administration or low-dose vaginal administration and 29 (66%) of 44 placentas with high-dose vaginal administration. When identified, microcrystalline cellulose and/or crospovidone is most commonly present on the maternal surfaces of the extraplacental membranes. The presence of microcrystalline cellulose and/or crospovidone was associated with smaller placental weight (Mann-Whitney U, P = 0.019). These fillers have a reasonable sensitivity for high-dose vaginal tablet use and are very specific. Although they are not diagnostic for misoprostol administration, they provide a finding that may prompt additional investigation into the nature of the vaginal tablet administered and the circumstances surrounding birth.

Injection of oral medication into the skin confirmed by infrared spectroscopy.

"Skin popping" refers to the practice of injecting drugs, most commonly heroin, subcutaneously or into granulation tissue. Pharmaceutical tablets meant for oral consumption are modified into solutions for injection. Excipients-inactive substances that serve as vehicles for medication-are often not filtered out before injection and result in abscess formation, granulomatous inflammation, and scarring. Common excipients used in the production of pharmaceutical tablets include starch, microcrystalline cellulose, magnesium stearate, silica, and polyvinylpyrrolidone (PVP). Identification of these exogenous materials is valuable in confirming the diagnosis of skin popping, especially when patients may not be forthcoming about their drug use. We present a case of subcutaneous oral medication injection in which PVP and cellulose were identified by Fourier transform infrared spectroscopy. Considering the variable cutaneous manifestations of injection drug abuse, recognition of histopathologic and chemical characteristics of exogenous material from oral medications is helpful for diagnosis and intervention.

An approach to assess and identify polymers in the health-care waste of a Brazilian university hospital.

This work presents the health-care waste (HCW) management and an approach to assess and identify polymers in a General Surgery Unit - Internment Service (GSU) of a Brazilian university hospital, to estimate the main polymers presenting in medical devices that are consumed during a year, discarded either as infecting (Group A) or as scarifying residue (Group E). Among the waste produced from the medical devices, 3.14 ton (98.79%) were composed of polymers (63.06% of plastics and 35.73% elastomers) while around 0.03 ton (1.21%) by metals. The proposed approach is composed of 4 steps: (1) Collecting data about consumed medical devices to be categorized into the residues Groups (A and E); (2) Identifying the polymeric composition with information provided by suppliers; (3) Characterizing the polymer functional groups by Fourier-Transform Infrared Spectroscopy (FTIR) and (4) Determining the polymer melting point by Differential Scanning Calorimetry (DSC). According to the results, the analyzed HCW was composed mainly of polypropylene (80.88%), high-density polyethylene (5.28%), polystyrene (4.51%), and cellulose (3.58%), from a total of 11 different polymers.

Eco-friendly active packaging consisting of nanostructured biopolymer matrix reinforced with TiO2 and essential oil: Application for preservation of refrigerated meat.

Biodegradable active packaging is required to replace petroleum-based plastics. In this study, a biopolymer-based packaging material was prepared using a casting method, which consisted of a cellulose nanofiber/whey protein matrix containing titanium dioxide particles (1% TiO2) and essential oil droplets (2% rosemary oil) as functional components. The ability of this packaging to protect lamb meat from chemical and microbial spoilage during 15 days of refrigerated storage (4 °C) was analysed. The meat samples were periodically analysed for microbial count, chemical stability (pH, lipid oxidation, lipolysis), and optical properties. The active packaging significantly reduced microbial growth, lipid oxidation, and lipolysis of the lamb meat during storage, which led to an increase in shelf life from around 6 to 15 days. These biopolymer-based active packaging materials may therefore be suitable for application in meat products.

Assessment of microplastic pollution: occurrence and characterisation in Vesijärvi lake and Pikku Vesijärvi pond, Finland.

In the last few years, several studies have investigated microplastics (MPs) in marine ecosystems, but data monitoring and assessing the occurrence in freshwater environments are still scarce. The present study aims to investigate the occurrence, distribution, and chemical composition of MP pollution in Vesijärvi lake and Pikku Vesijärvi pond close to the city of Lahti (Finland) in winter. Sediment, snow, and ice core samples were collected near the shore of these two aquatic systems. MPs were analysed and identified by a non-destructive method using Fourier transform infrared spectroscopy (FTIR) 2D imaging. The mean concentrations of MPs detected in sediment, snow, and ice samples were 395.5 ± 90.7 MPs/kg, 117.1 ± 18.4 MPs/L, and 7.8 ± 1.2 MPs/L, respectively. FTIR results showed the predominant abundance of microplastics, such as polyamides (up to 53.3%), polyethylene and polypropylene (up to 17.1%), and natural fragments such as cellulose (up to 45.8%) and wool (up 18.8%) in the same size range. The potential release of MPs arising from stormwaters and sport and recreational activities was evidenced.

First account of plastic pollution impacting freshwater fishes in the Amazon: Ingestion of plastic debris by piranhas and other serrasalmids with diverse feeding habits.

Reported here is the first evidence of plastic ingestion by freshwater fishes in the Amazon. Plastic bags, bottles, fishing gear, and other products are entering Amazonian water bodies and degrade into meso- and micro-plastic particles that may be ingested, either directly or indirectly via food chains, by fishes. Examination of stomach contents from 172 specimens of 16 serrasalmid species from lower Xingu River Basin revealed consumption of plastic particles by fishes in each of three trophic guilds (herbivores, omnivores, carnivores). Overall, about one quarter of specimens and 80% of species analyzed had ingested plastic particles ranging from 1 to 15 mm in length. Fourier transform infrared spectroscopy indicated 12 polymer types, including 27% identified as polyethylene, 13% polyvinyl chloride, 13% polyamide, 13% polypropylene, 7% poly(methyl methacrylate), 7% rayon, 7% polyethylene terephtalate, and 13% a blend of polyamide and polyethylene terephtalate. Dimensions of ingested plastic particles varied among trophic guilds, even though the frequency and mass of ingested particles were not significantly different among fishes with different feeding habits.

The Effects of Fillers and Binders on the Accuracy of Tablet Subdivision.

The effects of excipients on the accuracy of tablet subdivision are severely underinvestigated. In this study, placebo tablets were prepared using a combined mixture design of fillers and binders to evaluate the effect of these excipients on subdivision accuracy. The responses assessed were mass loss, mass variation, tablet fragmentation, and increased friability. Dicalcium phosphate dihydrate (DCP) gave rise to more uniform and denser tablets than microcrystalline cellulose (MCC), thus resulting in greater subdivision accuracy. The binder type, hydroxypropylcellulose (HPC) or polyvinylpyrrolidone (PVP), did not affect the subdivision of DCP tablets. On the contrary, the structural similarity between HPC and MCC led to improved subdivision accuracy for MCC tablets. A less accurate subdivision was observed in tablets prepared with a DCP-MCC combination; this finding could be attributed to irregular binder distribution in this matrix. An optimized response was built using desirability analysis. This study helps to illuminate the relationship between fillers and binders to guide formulation scientists in the development of tablets with better subdivision performance.

Process development for cigarette butts recycling into cellulose pulp.

Cigarette butts, which are usually thrown on the ground or into ordinary bins, have been recognized as toxic residues since may contain cigarette contaminants and chemicals produced during combustion. Therefore, contaminants in cigarette butts can be leached by rain into surface water and thereby contaminate the environment. In Brazil, according to the National Policy on Solid Waste, all residues must be disposed of in an environmentally friendly manner. Although cigarette butts are not mentioned in the law, due to their characteristics, they may be classified as hazardous waste. At the University of Brasilia, a cellulose pulp production process from cigarette butts has been developed employing alkaline pulping. This process is presented as an alternative to environmentally friendly final disposal of this residue. During the process, a dark liquor is generated, which was found to contain lignin, carbonyls, metals, nicotine and specific tobacco nitrosamines. The dark liquor was treated by acidification to promote lignin precipitation, coagulation with chitosan and Al2(SO4)3 to remove metals and organic compounds and ozonized to oxidize resistant chemicals. The dark liquor presented a high chemical oxygen demand (COD; 29,986mg/L), which was partially removed by precipitation (20%), chitosan coagulation (66%) and ozonation (45.8%). As the remaining COD was still high, we proposed reusing the clarified effluent in alkaline pulping, which seemed to be the easiest and most efficient procedure with the lowest cost.

Crospovidone and Microcrystalline Cellulose: A Novel Description of Pharmaceutical Fillers in the Gastrointestinal Tract.

Crospovidone and microcrystalline cellulose (MCC) are pharmaceutical fillers well known in the pulmonary pathology literature. Fillers are inactive substances incorporated into medications to facilitate drug delivery. By examining 545 consecutive gastrointestinal surgical specimens from 302 patients between September 11, 2015 and October 23, 2015, we identified the fillers in 29 specimens from 26 patients. The control group consisted of an equal number of consecutive site-matched specimens collected during this same time. Pertinent clinicopathologic data were analyzed, and 1 case was subject to special stains. To confirm the histologic diagnosis, a variety of fillers and medications common to the patients were processed. The fillers were found in 9% of all patients, and there were no specific clinicopathologic associations. In the gastrointestinal tract, crospovidone is nonbirefringent and has a coral shape with each segment composed of a pink core and purple coat; MCC is brightly birefringent with matchstick shape and clear color. Identical material was seen in the processed crospovidone and MCC powders, as well as oxycodone-acetaminophen and omeprazole tablets. In summary, crospovidone and MCC are common, biologically inert, and they are most often seen in the small bowel. Their presence outside of the luminal bowel may serve as a surrogate marker for perforation. Awareness of their morphology is important to distinguish fillers from parasites, calcifications, and other medications, particularly those linked to mucosal injury. We report the unique histomorphologic profile of these fillers as a helpful diagnostic aide, and caution that the fillers have slightly divergent features when compared with those described in the lung.

Bacterial cellulose and bacterial cellulose/polycaprolactone composite as tissue substitutes in rabbits' cornea / Celulose bacteriana e composto de celulose bacteriana/policaprolactone para substituto tissular na córnea de coelho

In order to test the performance of bacterial cellulose/polycaprolactone composite (BC/PCL) and pure bacterial cellulose (BC) as tissue substitutes in rabbits' cornea, a superficial ulcer containing 5mm in diameter and 0.2mm deep was made in the right cornea of 36 rabbits, then a interlayer pocket was created from the basis of this ulcer. Twelve rabbits received BC/PCL membrane and 12 were treated with BC membranes, both membranes with 8mm in diameter. The remaining rabbits received no membrane constituting the control group. The animals were clinically followed up for 45 days. Three animals of each group were euthanized at three, seven, 21, and 45 days after implantation for histological examination of the cornea along with the implant. Clinical observation revealed signs of moderate inflammatory process, decreasing from day 20th in the implanted groups. Histology showed absence of epithelium on the membranes, fibroplasia close to the implants, lymph inflammatory infiltrate with giant cells, collagen disorganization, with a predominance of immature collagen fibers in both groups with implants. Although inflammatory response is acceptable, the membranes used does not satisfactorily played the role of tissue substitute for the cornea during the study period.(AU)

Com objetivo de testar o desempenho do compósito celulose bacteriana/policaprolactona (CB/PCL) e da celulose bacteriana pura (CB) como substitutos teciduais em córnea de coelhos, foi realizada uma úlcera superficial de 5 mm de diâmetro e 0,2 mm de profundidade na córnea direita de 36 coelhos, criando-se um bolso interlamelar a partir da base dessa úlcera. Doze animais receberam a membrana do compósito CB/PCL e 12 foram tratados com membranas de CB, ambas com 8 mm de diâmetro, os coelhos restantes não receberam nenhuma membrana, constituindo o grupo controle. Os animais foram acompanhados clinicamente até 45 dias. Três animais de cada grupo sofreram eutanásia aos três, sete, 21 e 45 dias após o implante das membranas para análise histológica da córnea juntamente com o implante. À observação clínica, houve sinais de processo inflamatório moderado, diminuindo a partir do 20º dia nos grupos implantados. A histologia demonstrou ausência de epitélio sobre as membranas, fibroplasia próxima aos implantes, infiltrado inflamatório linfo-histiocitário com células gigantes, desorganização do colágeno, com predominância de fibras imaturas de colágeno em ambos os grupos com implantes. Embora a resposta inflamatória seja aceitável, as membranas utilizadas não desempenharam satisfatoriamente o papel de substituto tecidual para a córnea, no período estudado.(AU)

Development of a rapid method for the quantification of cellulose in tobacco by (13)C CP/MAS NMR.

A method was developed for rapid quantitative determination of cellulose in tobacco by utilizing (13)C cross polarization magic angle spinning NMR spectroscopy ((13)C CP/MAS NMR). Sample powder was loaded into NMR rotor, which was customized rotor containing a matched silicon tube as an intensity reference. (13)C CP/MAS NMR spectra of tobacco samples were processed with spectral deconvolution to obtain the area of the C-1 resonance at 105.5ppm and the internal standard at 0ppm. The ratio between the area of 105.5ppm and 0ppm of a set of standard cellulose samples was used to construct a calibration curve. The cellulose content of a tobacco sample was determined by comparison of the ratio between the area of 105.5ppm and 0ppm to the calibration curve. Results of this developed method showed good agreement with those obtained from chemical analysis. The proposed method has such advantages of accuracy, quickness and efficiency, and could be an alternative to chemical analyses of cellulose.

Inverse gas chromatography for natural fibre characterisation: Identification of the critical parameters to determine the Brunauer-Emmett-Teller specific surface area.

Inverse gas chromatography (IGC) is an alternative technique to determine the specific surface area of natural fibres. Natural fibres have a complex surface chemistry and unique microstructure that challenge the current capabilities to perform surface characterisation. This study investigated the influence of multiple parameters on the measured Brunauer-Emmett-Teller (BET) specific surface area for samples of flax, kenaf and BioMid(®) cellulose fibres using IGC. The BET surface area of kenaf and flax differed with 0.51m(2)g(-1) and 1.35m(2)g(-1) respectively, the former being similar to the cellulose fibres (0.54m(2)g(-1)). The data was calculated under conditions where the BET equation showed good linearity (R(2)⩾0.995). Repeatability was excellent so that two runs sufficed to obtain representative BET surface area values. The findings showed the choice of solvent was important for all specimens to avoid any misleading data comparison due to molecular orientation effects that impact the adsorbent-adsorbate interactions. The higher surface area of the flax sample, and its higher variability, was correlated with a higher surface roughness observed under optical microscopy. Packing the chromatography column with long or chopped fibres produced results that were statistically insignificant.