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1.
Nutrients ; 14(18)2022 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-36145107

RESUMEN

Easier recognition and enhanced visibility of healthy options supposedly increase healthy choices, but real-world evidence remains scarce. Addressing this knowledge gap, we promoted nutritionally favourable foods in a workplace cafeteria with three choice-architectural strategies-priming posters, point-of-choice nutrition labels, and improved product placement-and assessed their effects on visual attention, food choices, and food consumption. Additionally, we developed a method for analysing real-world eye-tracking data. The study followed a pretest-posttest design whereby control and intervention condition lasted five days each. We monitored visual attention (i.e., total number and duration of fixations) and food choices with eye tracking, interviewed customers about perceived influences on food choices, and measured cafeteria-level food consumption (g). Individual-level data represents 22 control and 19 intervention participants recruited at the cafeteria entrance. Cafeteria-level data represents food consumption during the trial (556/589 meals sold). Results indicated that the posters and labels captured participants' visual attention (~13% of fixations on defined areas of interest before food choices), but the intervention had insignificant effects on visual attention to foods, on food choices, and on food consumption. Interviews revealed 17 perceived influences on food choices, the most common being sensory appeal, healthiness, and familiarity. To conclude, the intervention appeared capable of attracting visual attention, yet ineffective in increasing healthier eating. The developed method enabled a rigorous analysis of visual attention and food choices in a natural choice setting. We discuss ways to boost the impact of the intervention on behaviour, considering target groups' motives. The work contributes with a unique, mixed-methods approach and a real-world setting that enabled a multi-dimensional effects evaluation with high external validity.


Asunto(s)
Servicios de Alimentación , Conducta de Elección , Preferencias Alimentarias , Humanos , Comidas , Lugar de Trabajo
2.
Open Forum Infect Dis ; 9(7): ofac214, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35791357

RESUMEN

Background: The coronavirus disease 2019 (COVID-19) epidemic overwhelmed local contact tracing (CT) efforts in many countries. In Finland, severe acute respiratory syndrome coronavirus 2 incidence and mortality were among the lowest in Europe during 2020-2021. We evaluated CT efficiency, effectiveness, and transmission settings. Methods: Polymerase chain reaction (PCR) test-positive COVID-19 cases and high-risk contacts in the population-based CT database of Pirkanmaa Hospital District (population 540 000) during June 2020-May 2021 were interviewed. Results: Altogether 353 926 PCR tests yielded 4739 (1.3%) confirmed cases (average 14-day case notification rate, 34 per 100 000 population); about 99% of confirmed cases and high-risk contacts were reached by a CT team. Of 26 881 high-risk contacts who were placed in quarantine, 2275 subsequently tested positive (48% of new cases), 825 (17%) had been in quarantine ≥48 hours before symptoms, and 3469 (77%) of locally acquired cases were part of transmission chains with an identified setting. The highest secondary attack rates were seen in households (31%), healthcare patients (18%), and private functions (10%). Among the 311 hospitalized patients, COVID-19 diagnosis or exposure was known in 273 (88%) before emergency room admission (identified patients). Healthcare workers had the highest proportion of work-related infections (159 cases [35%]). The source of infection was classifiable in 65% and was most commonly a coworker (64 cases [62%]). Conclusions: Our data demonstrate the role of effective testing and CT implementation during the cluster phase of COVID-19 spread. Although half of newly diagnosed cases were already in quarantine, targeted public health measures were needed to control transmission. CT effectiveness during widespread community transmission should be assessed.

3.
Euro Surveill ; 24(38)2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31552821

RESUMEN

BackgroundTwo epidemiologically-unrelated clusters of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae were detected among several healthcare facilities (HCF) in Finland by routine surveillance using whole genome sequencing (WGS).AimThe objective was to investigate transmission chains to stop further spread of the responsible strain.MethodsIn this observational retrospective study, cases were defined as patients with K. pneumoniae KPC-3 sequence type (ST)512 strain detected in Finland from August 2013 to May 2018. Environmental specimens were obtained from surfaces, sinks and toilets in affected wards. WGS was performed on K. pneumoniae cultures using Illumina MiSeq platform and data were analysed using Ridom SeqShere software K. pneumoniae core genome multilocus sequence typing (cgMLST) scheme. Epidemiological information of the cases was provided by HCFs.ResultsWe identified 20 cases in six HCFs: cluster 1 included 18 cases in five HCFs and cluster 2 two cases in one HCF. In cluster 1, a link with a foreign country was unclear, 6/18 cases without overlapping stay had occupied the same room in one of the five HCFs within > 3 years. In cluster 2, the index case was transferred from abroad, both cases occupied the same room 8 months apart. A strain identical to that of the two cases in cgMLST was isolated from the toilet of the room, suggesting a clonal origin.ConclusionsThe clusters were mostly related to case transfer between facilities and likely involved environmental transmission. We show that CPE surveillance using WGS and collaboration between hospitals are crucial to identify clusters and trace transmission chains.


Asunto(s)
Proteínas Bacterianas/genética , Monitoreo del Ambiente/métodos , Genoma Bacteriano , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/aislamiento & purificación , Tipificación de Secuencias Multilocus , Secuenciación Completa del Genoma , beta-Lactamasas/genética , Proteínas Bacterianas/aislamiento & purificación , Infección Hospitalaria/epidemiología , Finlandia/epidemiología , Humanos , Epidemiología Molecular , Estudios Retrospectivos , beta-Lactamasas/aislamiento & purificación
4.
Infect Dis (Lond) ; 50(1): 52-58, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29161942

RESUMEN

BACKGROUND: Staphylococcus aureus bacteremia (SAB) causes a significant burden on the population. Several infection control measures have been implemented in Pirkanmaa county to combat a local epidemic with methicillin-resistant Staphylococcus aureus (MRSA). We aimed to study the epidemiology of SAB and antibiotic resistance of S. aureus and the possible influence of improved infection control. METHODS: Register data from 2005 to 2015 were retrospectively analysed to study the antimicrobial susceptibility, the incidence and mortality in SAB in a population-based setting. RESULTS: The incidence of SAB increased during the study period from 21.6 to 35.8/100,000 population. The number of both health care-associated (HA) and community-associated (CA) cases has increased. The incidence of MSSA bacteremia increased from 19.9 to 35.2/100,000 population in Pirkanmaa in parallel to other parts of Finland. The incidence of MRSA bacteremia was 10-fold (4.5/100,000 population) higher in 2011 than in other parts of the country, but sank to the national level (0.59/100,000 population) in 2015. The fatality rate decreased from 22% to 17%. The proportion of penicillin-susceptible Staphylococcus aureus (PSSA) increased from 23.9% in 2008 to 43.1% in 2015. CONCLUSION: The incidence of both HA and CA SAB has increased since 2005. Conversely, the proportion of MRSA and PRSA bacteremia has decreased. Promotion of infection control measures may have reduced the incidence of MRSA bacteremia but not the overall incidence of SAB. The rising proportion of PSSA enables the use of targeted, narrow spectrum antimicrobials.


Asunto(s)
Bacteriemia/epidemiología , Bacteriemia/microbiología , Infección Hospitalaria/epidemiología , Infección Hospitalaria/microbiología , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/fisiología , Adolescente , Adulto , Anciano , Niño , Preescolar , Infecciones Comunitarias Adquiridas/epidemiología , Infecciones Comunitarias Adquiridas/microbiología , Femenino , Finlandia/epidemiología , Humanos , Incidencia , Lactante , Recién Nacido , Control de Infecciones/normas , Control de Infecciones/tendencias , Masculino , Staphylococcus aureus Resistente a Meticilina/fisiología , Persona de Mediana Edad , Resistencia a las Penicilinas/fisiología , Estudios Retrospectivos , Adulto Joven
5.
Infect Dis (Lond) ; 49(7): 493-500, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28276799

RESUMEN

BACKGROUND: The aim of this study was to assess the association of methicillin resistance and penicillinase production with clinical characteristics and outcome of Staphylococcus aureus bacteremia. METHODS: For 126 patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, 378 age- and gender-matched controls with methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia were selected. Of controls, 126 had bacteremia caused by penicillin-susceptible strains (PSSA) and 252 by penicillinase-producing strains (PRSA). Underlying diseases, clinical course and mortality were retrospectively assessed. RESULTS: Patients with MRSA bacteremia were more often smokers than patients with MSSA bacteremia (OR 2.34, 95% CI 1.27-4.32). MRSA bacteremia was more often healthcare-associated (OR 4.23, 95% CI 2.47-7.24), associated with central venous catheters (OR 2.09, 95% CI 1.27-3.47), glucocorticoid therapy (OR 1.82, 95% CI 1.12-2.93) and prior surgery (OR 2.32, 95% CI 1.43-3.76). Patients with MRSA bacteremia received appropriate empiric antibiotic (31%) less often than controls (98%). Mortality within 28 days was higher in MRSA bacteremia (26.8%) than in MSSA bacteremia (15.5%) (OR 2.00, 95% CI 1.20-3.34), PRSA bacteremia (17.0%) (OR 1.79 95% CI 1.04-3.09) or PSSA bacteremia (12.5%) (OR 2.56 95% CI 1.27-5.15). The difference remained after adjusting for underlying diseases and foci. There was no significant difference in clinical course between PRSA and PSSA bacteremias. CONCLUSIONS: MRSA bacteremia was associated with poorer outcome than either PRSA or PSSA bacteremia. We corroborated several risk factors found in previous studies.


Asunto(s)
Antibacterianos/uso terapéutico , Bacteriemia/microbiología , Bacteriemia/patología , Infecciones Estafilocócicas/microbiología , Infecciones Estafilocócicas/patología , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/aislamiento & purificación , Anciano , Bacteriemia/tratamiento farmacológico , Femenino , Humanos , Masculino , Resistencia a la Meticilina , Resistencia a las Penicilinas , Estudios Retrospectivos , Infecciones Estafilocócicas/tratamiento farmacológico , Resultado del Tratamiento
6.
BMC Infect Dis ; 17(1): 161, 2017 02 21.
Artículo en Inglés | MEDLINE | ID: mdl-28222687

RESUMEN

BACKGROUND: Extensive backflow of treated wastewater caused household water contamination in a Finnish town in 2007. The drinking water of 9 500 residents became heavily polluted with faecal microbes, resulting in a large gastroenteritis epidemic. Cases of reactive arthritis, milder joint symptoms and prolonged gastrointestinal symptoms were observed after the outbreak. A follow-up survey was performed to study less familiar long-term health consequences within a year from the outbreak. METHODS: The contaminated group comprised a sample of residents of the area with polluted water supply (N = 323) and the control group a sample of residents in a nearby municipality (N = 186). The presence of 20 general symptoms or complaints was inquired by a mail survey. Quarterly prevalence of each symptom or complaint was measured. Twelve of these proceeded to further analysis. RESULTS: The response rate was 53% (323/615) in the contaminated group and 54% (186/343) in the control group. Rash, eye irritation, heartburn and weight loss were more prevalent in the contaminated group during the first year quarter. In the last year quarter, only eye irritation was significantly more common in the contaminated group. CONCLUSION: The excess prevalence of four complaints at the first year quarter can be explained by acute gastroenteritis or intensive water chlorination. The excess prevalence of eye irritation at the fourth year quarter cannot be explained by chlorination anymore but might be a sign of co-existing reactive joint disease. In general, long-term consequences of the outbreak can be considered minor in terms of the surveyed symptoms or complaints.


Asunto(s)
Brotes de Enfermedades/estadística & datos numéricos , Agua Potable/efectos adversos , Gastroenteritis/epidemiología , Aguas Residuales , Microbiología del Agua , Contaminación del Agua/efectos adversos , Enfermedades Transmitidas por el Agua/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Niño , Preescolar , Agua Potable/microbiología , Femenino , Finlandia/epidemiología , Estudios de Seguimiento , Gastroenteritis/diagnóstico , Gastroenteritis/etiología , Encuestas Epidemiológicas , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Prevalencia , Encuestas y Cuestionarios , Enfermedades Transmitidas por el Agua/diagnóstico , Enfermedades Transmitidas por el Agua/etiología , Adulto Joven
7.
Angew Chem Int Ed Engl ; 55(46): 14455-14458, 2016 11 07.
Artículo en Inglés | MEDLINE | ID: mdl-27761976

RESUMEN

Despite the structural, load-bearing role of cellulose in the plant kingdom, countless efforts have been devoted to degrading this recalcitrant polysaccharide, particularly in the context of biofuels and renewable nanomaterials. Herein, we show how the exposure of plant-based fibers to HCl vapor results in rapid degradation with simultaneous crystallization. Because of the unchanged sample texture and the lack of mass transfer out of the substrate in the gas/solid system, the changes in the crystallinity could be reliably monitored. Furthermore, we describe the preparation of cellulose nanocrystals in high yields and with minimal water consumption. The study serves as a starting point for the solid-state tuning of the supramolecular properties of morphologically heterogeneous biological materials.

8.
RSC Adv ; 6(92): 89051-89056, 2016 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-28496970

RESUMEN

Hybrid aerogels consisting of cellulose nanofibers (CNF) and modified few-walled carbon nanotubes (FWCNT) are investigated under cyclic mechanical compression to explore "electrical fatigue". For this purpose the FWCNTs were hydrophilized, thus promoting their aqueous dispersibility to allow FWCNT/CNF hybrid hydrogels, followed by freeze-drying to obtain hybrid aerogels. The optimized composition consisting of FWCNT/CNF 20/80 wt/wt showed conductivity of 10-5 S cm-1 as promoted due to double percolation, and showed only small changes in electrical and mechanical behaviour upon cycling 100 times. The electrical behaviour under cycled compression shows good stability and reversibility.

9.
J Phys Chem B ; 119(49): 15275-86, 2015 Dec 10.
Artículo en Inglés | MEDLINE | ID: mdl-26560798

RESUMEN

Block copolymers of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) with varying block sizes were synthesized by consecutive reversible addition-fragmentation chain transfer (RAFT) polymerization and then exposed to cellulose substrates with different anionic charge density. The extent and dynamics of quaternized PDMAEMA-b-POEGMA adsorption on regenerated cellulose, cellulose nanofibrils (CNF), and (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNF) was determined by using electromechanical and optical techniques, namely, quartz crystal microbalance (QCM-D) and surface plasmon resonance (SPR), respectively. PDMAEMA-b-POEGMA equilibrium adsorption increased with the anionic charge of cellulose, an indication of electrostatic interactions. Such an observation was further confirmed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Depending on their architecture, adsorption on TOCNF of some of the PDMAEMA-b-POEGMA copolymers produced a significant reduction in QCM frequency, as expected from large mass uptake, while surprisingly, other copolymers induced the opposite effect. This latter, remarkable behavior was ascribed to coupled water expulsion from the interface upon charge neutralization of anionic surface sites with adsorbing cationic polymer segments. These observations were further investigated with SPR and QCM-D measurements using deuterium oxide solvent exchange to determine the amount of coupled water at the TOCNF-block copolymer interface. Finally, random copolymers with similar composition adsorbed to a larger extent compared to the respective block copolymers, revealing the effect of adsorbed loops and tails as well as hydration.

10.
Infect Dis (Lond) ; 47(11): 801-7, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26135710

RESUMEN

BACKGROUND: A large healthcare-associated epidemic mainly caused by one methicillin-resistant Staphylococcus aureus (MRSA) strain broke out in Pirkanmaa County, Finland, in 2001. This study describes the impact of infection control and screening practices on the epidemic. METHODS: The number of hospital-acquired (HA)-MRSA findings obtained from clinical and screening samples during the epidemic was calculated. Strains were typed by pulsed-field electrophoresis (PFGE) or spa typing. Strain type distribution was studied in relation to sample type, year of the epidemic and site of transmission. Several infection control interventions were launched stepwise and screening protocols were expanded. RESULTS: A total of 4118 cases were identified during 2001-2014, of which 3527 were classified as HA. One strain (spa t067) dominated in the epidemic. HA-MRSA cases decreased constantly from the year 2011. The number of new HA-MRSA cases was 57% less in the year 2014 (n = 171) as compared with the year 2011 (n = 399). The proportion of the epidemic strain declined significantly over the years. Screening samples comprised 71% (2439/3527) and clinical samples 29% (1034/3527) of HA-MRSA findings. The number of HA-MRSA cases found from clinical samples started to decrease when screening was expanded. An increase in hand-rub consumption was associated with a decrease in transmissions in Tampere University Hospital (TAUH). CONCLUSION: Implementation of universal screening together with several other interventions is effective in containing an MRSA epidemic. The proportion of other than Pirkanmaa epidemic (PE)-MRSA strain findings increased throughout the period, indicating the changing epidemiology of MRSA.


Asunto(s)
Infección Hospitalaria/prevención & control , Control de Infecciones/métodos , Staphylococcus aureus Resistente a Meticilina/fisiología , Infecciones Estafilocócicas/prevención & control , Infección Hospitalaria/epidemiología , Infección Hospitalaria/microbiología , Finlandia/epidemiología , Hospitales , Humanos , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología
11.
Infect Dis (Lond) ; 47(7): 499-503, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25761612

RESUMEN

Reports of respiratory tract infections in a rehabilitation center for alcoholics triggered the epidemiological investigations in Tampere, Finland. Twenty-nine out of 40 residents (attack rate 73%) and four members of staff fulfilled the case criteria: cough; worsening of dyspnea; or rhinitis with or without fever. Ten cases were hospitalized, one needed treatment in the intensive care unit. All cases recovered. Serum hMPV antibody titer was high (10 240 or more) in 20 (69%) of the 29 tested cases and the difference was significant when compared with the titer measured from the voluntary laboratory personnel (n = 14, p < 0.001). The titers were rising in three out of the five cases from whom coupled samples could be obtained. Rt-PCR for hMPV was positive in three out of the eight tested cases. No other causative agent for the outbreak was detected. The outcome of hMPV infection among institutionalized smoking alcoholics was good with no mortality.


Asunto(s)
Metapneumovirus/aislamiento & purificación , Infecciones por Paramyxoviridae/diagnóstico , Infecciones por Paramyxoviridae/epidemiología , Anciano , Anticuerpos Antivirales/sangre , Brotes de Enfermedades , Femenino , Finlandia/epidemiología , Humanos , Masculino , Metapneumovirus/clasificación , Persona de Mediana Edad , Infecciones por Paramyxoviridae/virología , Centros de Tratamiento de Abuso de Sustancias , Carga Viral
12.
Angew Chem Int Ed Engl ; 54(18): 5383-8, 2015 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-25772264

RESUMEN

Hybrid nanocomposites were constructed based on colloidal nanofibrillar hydrogels with interpenetrating supramolecular hydrogels, displaying enhanced rheological yield strain and a synergistic improvement in storage modulus. The supramolecular hydrogel consists of naphthyl-functionalized hydroxyethyl cellulose and a cationic polystyrene derivative decorated with methylviologen moieties, physically cross-linked with cucurbit[8]uril macrocyclic hosts. Fast exchange kinetics within the supramolecular system are enabled by reversible cross-linking through the binding of the naphthyl and viologen guests. The colloidal hydrogel consists of nanofibrillated cellulose that combines a mechanically strong nanofiber skeleton with a lateral fibrillar diameter of a few nanometers. The two networks interact through hydroxyethyl cellulose adsorption to the nanofibrillated cellulose surfaces. This work shows methods to bridge the length scales of molecular and colloidal hybrid hydrogels, resulting in synergy between reinforcement and dynamics.

13.
J Colloid Interface Sci ; 448: 73-8, 2015 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-25721858

RESUMEN

We evaluated the effect of polyelectrolyte complexes (PEC) with varying balance of charges on the flocculation of precipitated calcium carbonate (PCC) particles. PECs composed of polyacrylamides carrying opposite charges (A-PAM and C-PAM) were investigated in terms of PCC floc shear resistance and re-flocculation effects. Light transmission was used in real time to monitor the dynamics of flocculation under shear fields. Compared to the single polyelectrolytes, PECs greatly enhanced particle re-flocculation while minor differences in shear resistance were observed. Shear resistance and re-flocculation depended strongly on the molecular weight and charge ratio of the PEC components. In order to achieve floc stability and re-flocculation conditions a minimum concentration of charge-asymmetric PEC should be applied.


Asunto(s)
Resinas Acrílicas/química , Carbonato de Calcio/química , Electrólitos/química , Precipitación Química , Floculación
14.
Angew Chem Weinheim Bergstr Ger ; 127(18): 5473-5478, 2015 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-27478263

RESUMEN

Hybrid nanocomposites were constructed based on colloidal nanofibrillar hydrogels with interpenetrating supramolecular hydrogels, displaying enhanced rheological yield strain and a synergistic improvement in storage modulus. The supramolecular hydrogel consists of naphthyl-functionalized hydroxyethyl cellulose and a cationic polystyrene derivative decorated with methylviologen moieties, physically cross-linked with cucurbit[8]uril macrocyclic hosts. Fast exchange kinetics within the supramolecular system are enabled by reversible cross-linking through the binding of the naphthyl and viologen guests. The colloidal hydrogel consists of nanofibrillated cellulose that combines a mechanically strong nanofiber skeleton with a lateral fibrillar diameter of a few nanometers. The two networks interact through hydroxyethyl cellulose adsorption to the nanofibrillated cellulose surfaces. This work shows methods to bridge the length scales of molecular and colloidal hybrid hydrogels, resulting in synergy between reinforcement and dynamics.

15.
ACS Appl Mater Interfaces ; 6(24): 22622-7, 2014 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-25454578

RESUMEN

A new method to produce cellulose nanofibrils (CNF) is proposed to reduce the energy demand during deconstruction of precursor fibers suspended in aqueous media. Microemulsions were formulated with aqueous solutions of urea or ethylenediamine and applied to disrupt interfibril hydrogen bonding. Compared to typical fibrillation of lignin-containing and lignin-free fibers, pretreatment with microemulsion systems allowed energy savings during microfluidization of 55 and 32%, respectively. Moreover, microemulsion processing facilitated smaller-scale CNF structures (higher degrees of deconstruction), with higher water retention value (WRV) and surface area. Urea-containing microemulsions were found to be most effective in reducing energy consumption and in weakening the cellulosic matrix. Films prepared from CNF processed after pretreatment with urea-containing microemulsions presented a more uniform fiber network and produced films with smoother surfaces compared to those based on ethylenediamine. The lignin-containing CNF (LCNF) produced denser films than those obtained from lignin-free CNF. The mechanical properties of films obtained after application of microemulsion pretreatment were compared, and the benefits of the proposed approach were further confirmed. Overall, fiber deconstruction after microemulsion treatment is a step toward energy-efficient production of nanocellulose.


Asunto(s)
Etilenodiaminas/química , Colágenos Fibrilares/síntesis química , Colágenos Fibrilares/ultraestructura , Nanofibras/química , Nanofibras/ultraestructura , Urea/química , Cristalización/métodos , Emulsionantes , Emulsiones/química , Ensayo de Materiales , Tamaño de la Partícula , Agua/química
16.
Carbohydr Polym ; 108: 34-40, 2014 Aug 08.
Artículo en Inglés | MEDLINE | ID: mdl-24751244

RESUMEN

The aim of this work was to study the effect of solution conditions and polysaccharide structure on their Layer-by-Layer (LbL) deposition on nanofibrillated cellulose (NFC). Multilayer build-up of cellulose derivatives and chitosan on NFC model surfaces was studied using Quartz Crystal Microbalance with Dissipation (QCM-D) and Colloidal Probe Microscopy (CPM). The type of cationic polysaccharide was found to significantly affect the multilayer build-up and surface interactions. Cationic cellulose derivative quaternized hydroxyethyl cellulose ethoxylate (HECE) formed highly water-swollen layers with carboxymethyl cellulose (CMC), and the build-up was markedly influenced by both the ionic strength and pH. The ionic strength did not significantly influence the multilayer build-up of chitosan-CMC system, and adsorbed chitosan layers decreased the viscoelasticity of the system. Based on the results, it was also confirmed that electrostatic interaction is not the only driving force in case of the build-up of polysaccharide multilayers on nanofibrillated cellulose.


Asunto(s)
Celulosa/química , Nanoestructuras/química , Polisacáridos/química , Celulosa/análogos & derivados , Quitosano/análogos & derivados , Quitosano/química
17.
Bioresour Technol ; 161: 55-62, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24686371

RESUMEN

The amount of residual lignin and hemicelluloses in softwood fibers was systematically varied by SO2-ethanol-water fractionation for integrated biorefinery with nanomaterial and biofuel production. On the basis of their low energy demand in mechanical processing, the fibers were deconstructed to lignocellulose nanofibrils (LCNF) and used as substrate for bioconversion. The effect of LCNF composition on saccharification via multicomponent enzymes was investigated at different loadings. LCNF digestibility was compared with the enzyme activity measured with a quartz crystal microbalance. LCNF hydrolysis rate gradually decreased with lignin and hemicellulose concentration, both of which limited enzyme accessibility. Enzyme inhibition resulted from non-productive binding of proteins onto lignin. Near complete LCNF hydrolysis was achieved, even at high lignin and hemicellulose content. Sugar yields for LCNF were higher than those for precursor SEW fibers, highlighting the benefits of high surface area in LCNF.


Asunto(s)
Lignina/química , Nanofibras/química , Polisacáridos/química , Fraccionamiento Químico , Etanol , Hidrólisis , Picea , Dióxido de Azufre
18.
Biomacromolecules ; 15(3): 876-81, 2014 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-24456129

RESUMEN

Films and hydrogels consisting of cellulose nanofibrils (CNF) were modified by covalent EDC/NHS coupling of luminescent, water-dispersible carbon dots (CDs). Quartz crystal microgravimetry with dissipation monitoring (QCM-D) and surface plasmon resonance (SPR) were used to investigate the attachment of CDs on carboxymethylated CNF (CM-CNF). As the first reported use of CD in nanocellulose products, we provide proof-of-concept for the synthesis of transparent and fluorescent nanopaper and for its tunable luminescence as confirmed by confocal microscopy imaging.


Asunto(s)
Adsorción , Celulosa/química , Sustancias Luminiscentes/química , Nanofibras/química , Carbono/química , Cristalización , Luminiscencia , Nanopartículas/química , Cuarzo/química , Resonancia por Plasmón de Superficie , Propiedades de Superficie , Agua/química
19.
PLoS One ; 9(1): e85457, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24465569

RESUMEN

An extensive drinking water-associated gastroenteritis outbreak took place in the town of Nokia in Southern Finland in 2007. 53% of the exposed came down with gastroenteritis and 7% had arthritis-like symptoms (joint swelling, redness, warmth or pain in movement) according to a population-based questionnaire study at 8 weeks after the incident. Campylobacter and norovirus were the main pathogens. A follow-up questionnaire study was carried out 15 months after the outbreak to evaluate the duration of gastrointestinal and joint symptoms. 323 residents of the original contaminated area were included. The response rate was 53%. Participants were inquired about having gastroenteritis during the outbreak and the duration of symptoms. Of those with gastroenteritis, 43% reported loose stools and abdominal pain or distension after the acute disease. The prevalence of symptoms declined promptly during the first 3 months but at 15 months, 11% reported continuing symptoms. 32% of the respondents with gastroenteritis reported subsequent arthritis-like symptoms. The disappearance of arthritis-like symptoms was more gradual and they levelled off only after 5 months. 19% showed symptoms at 15 months. Prolonged gastrointestinal symptoms correlated to prolonged arthritis-like symptoms. High proportion of respondents continued to have arthritis-like symptoms at 15 months after the epidemic. The gastrointestinal symptoms, instead, had declined to a low level.


Asunto(s)
Gastroenteritis/epidemiología , Gastroenteritis/virología , Artropatías/epidemiología , Artropatías/virología , Encuestas y Cuestionarios , Microbiología del Agua , Heces/virología , Finlandia/epidemiología , Estudios de Seguimiento , Humanos , Incidencia , Prevalencia , Factores de Tiempo
20.
Biomacromolecules ; 15(1): 373-9, 2014 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-24328321

RESUMEN

Developing sustainable chemical methods to synthesize silver nanoparticles has drawn significant research interest. Due to their unique and well-defined physical-chemical properties, cellulose nanocrystals (CNCs) have become one of the most promising renewable nanomaterials. Here we use CNC to mediate silver nanoparticle synthesis and elucidate the effect of CNC surface chemistry (as defined by sulfate groups) in nanoparticle formation and nucleation in the presence of borohydride reduction. Pristine CNCs produced by sulfuric acid hydrolysis and partially desulfated CNCs mediated the formation of silver nanoparticles of different sizes (and size distribution) following different rates of formation, as determined by transmission electron microscopy (TEM) and UV-vis spectroscopy. The results shed light on methods to stabilize silver nanoparticles, control their nucleation, and highlight the potential of CNCs in metal nanoparticle synthesis.


Asunto(s)
Celulosa/síntesis química , Nanopartículas del Metal/química , Plata/química , Sulfatos/síntesis química , Cristalización
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