Shaping helical electrospun filaments: a review.

Nature abounds with helical filaments designed for specific tasks. For instance, some plants use tendrils to coil and attach to the surroundings, while Spiroplasma, a helical bacterium, moves by inverting the helical handedness along the filament axis. Therefore, developing methods to shape filaments on demand to exhibit a diversity of physical properties and shapes could be of interest to many fields, such as the textile industry, biomedicine or nanotechnology. Electrospinning is a simple and versatile technique that allows the production of micro and nanofibres with many different helical shapes. In this work, we review the different electrospinning procedures that can be used to obtain helical shapes similar to those found in natural materials. These techniques also demonstrate that the creation of helical shapes at the micro/nanoscale is not limited by the chirality of the building blocks at the molecular level, a finding which opens new horizons on filament shaping.

Hygroscopic study of hydroxypropylcellulose : Structure and strain-induced birefringence of capillary bridges.

The hygroscopic method developed previously for studies of lyotropic liquid crystals is used for the first time in experiments with millimetric capillary bridges made of a hydroxypropylcellulose/water mixture. Composition of such very small samples is controlled via humidity of the surrounding air. By a slow and well-controlled drying of initially isotropic samples, the isotropic/anisotropic phase transition is crossed and polydomain pseudo-isotropic capillary bridges are prepared. Kept in an atmosphere of constant humidity, these bridges are stretched and the strain-induced birefringence [Formula: see text] n is measured as a function of the draw ratio [Formula: see text] . The variation of [Formula: see text] n with [Formula: see text] is interpreted in terms of an affine uniaxial deformation of the initial pseudo-isotropic texture.

Nanocrystalline cellulose applied simultaneously as the gate dielectric and the substrate in flexible field effect transistors.

Cotton-based nanocrystalline cellulose (NCC), also known as nanopaper, one of the major sources of renewable materials, is a promising substrate and component for producing low cost fully recyclable flexible paper electronic devices and systems due to its properties (lightweight, stiffness, non-toxicity, transparency, low thermal expansion, gas impermeability and improved mechanical properties).Here, we have demonstrated for the first time a thin transparent nanopaper-based field effect transistor (FET) where NCC is simultaneously used as the substrate and as the gate dielectric layer in an 'interstrate' structure, since the device is built on both sides of the NCC films; while the active channel layer is based on oxide amorphous semiconductors, the gate electrode is based on a transparent conductive oxide.Such hybrid FETs present excellent operating characteristics such as high channel saturation mobility (>7 cm(2) V (-1) s(-1)), drain-source current on/off modulation ratio higher than 10(5), enhancement n-type operation and subthreshold gate voltage swing of 2.11 V/decade. The NCC film FET characteristics have been measured in air ambient conditions and present good stability, after two weeks of being processed, without any type of encapsulation or passivation layer. The results obtained are comparable to ones produced for conventional cellulose paper, marking this out as a promising approach for attaining high-performance disposable electronics such as paper displays, smart labels, smart packaging, RFID (radio-frequency identification) and point-of-care systems for self-analysis in bioscience applications, among others.

Improved mechanical stability of acetoxypropyl cellulose upon blending with ultranarrow PbS nanowires in Langmuir monolayer matrix.

Cellulose and cellulose derivatives have long been used as membrane fabrication. Langmuir monolayer behavior, which naturally mimics membranes, of acetoxypropyl cellulose (APC) and lead sulfide (PbS) nanowire mixtures at different volume ratios is reported. Surface pressure (π)-area (A) isotherms of APC and PbS nanowires mixtures at different volume ratios show a gradual decrease in the monolayer area with increasing volume fraction of PbS nanowires. Change of surface potential with monolayer area at different volume ratios also reveals a gradual increase in the surface potential indicating incorporation of PbS nanowires within APC matrix. The compressibility and elastic constants measurements reveal an enhancement of the elasticity upon incorporation of PbS nanowires up to certain volume fractions. An enhancement in stability of the blend is observed upon PbS nanowire incorporation to the APC matrix. Rheological measurements also support the robustness of the mixture of APC and PbS nanowires in 3D bulk phase. Such robust ultrathin films of cellulose based-nanowire blend obtained by means of the Langmuir technique may lead to novel routes for designing cellulosic-based thin films and membranes.

Nannochloropsis oceanica microalga feeding increases long-chain omega-3 polyunsaturated fatty acids in lamb meat.

To test the hypothesis that lambs fed freeze-dried Nannochloropsis oceanica (NO) biomass will have a higher deposition of EPA in tissues than those fed other Nannochloropsis EPA-sources, we fed 28 lambs with one of four diets: i) C, control, without EPA; ii) O, with 1.2% Nannochloropsis oil; iii) SD, with 12.3% spray-dried NO biomass; iv) FD, with 9.2% freeze-dried NO biomass. Dry matter intake, growth, tissues fatty acid composition, oxidative stability and sensory traits of the resultant meat were evaluated. The EPA was highest in tissues of lambs fed SD and FD compared with O but was similar between SD and FD. Total trans-18:1 did not differ among treatments, but the t10/t11-18:1 ratio decreased with all EPA containing diets. EPA diets were also supplemented with Vitamin E preventing the lipid oxidation in EPA-enriched meat and the meat sensory traits were not affected although occasionally some off-flavours were detected in FD meat.

BCAR4 induces antioestrogen resistance but sensitises breast cancer to lapatinib.

BACKGROUND: High BCAR4 and ERBB2 mRNA levels in primary breast cancer associate with tamoxifen resistance and poor patient outcome. We determined whether BCAR4 expression sensitises breast cancer cells to lapatinib, and identifies a subgroup of patients who possibly may benefit from ERBB2-targeted therapies despite having tumours with low ERBB2 expression. METHODS: Proliferation assays were applied to determine the effect of BCAR4 expression on lapatinib treatment. Changes in cell signalling were quantified with reverse-phase protein microarrays. Quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) of ERBB2 and BCAR4 was performed in 1418 primary breast cancers. Combined BCAR4 and ERBB2 mRNA levels were evaluated for association with progression-free survival (PFS) in 293 oestrogen receptor-α (ER)-positive patients receiving tamoxifen as first-line monotherapy for recurrent disease. RESULTS: BCAR4 expression strongly sensitised ZR-75-1 and MCF7 breast cancer cells to the combination of lapatinib and antioestrogens. Lapatinib interfered with phosphorylation of ERBB2 and its downstream mediators AKT, FAK, SHC, STAT5, and STAT6. Reverse transcriptase-PCR analysis showed that 27.6% of the breast cancers were positive for BCAR4 and 22% expressed also low levels of ERBB2. The clinical significance of combining BCAR4 and ERBB2 mRNA status was underscored by the finding that the group of patients having BCAR4-positive/ERBB2-low-expressing cancers had a shorter PFS on tamoxifen treatment than the BCAR4-negative group. CONCLUSION: This study shows that BCAR4 expression identifies a subgroup of ER-positive breast cancer patients without overexpression of ERBB2 who have a poor outcome and might benefit from combined ERBB2-targeted and antioestrogen therapy.

Cellulose-based liquid crystalline photoresponsive films with tunable surface wettability.

We report on a new type of liquid crystalline cellulosic films with light controllable reversible wettability. The films are prepared from a thermotropic cellulose derivative functionalized with azo-containing groups. These groups exhibit dynamic changes in interfacial properties in response to UV irradiation. The UV irradiation induces trans-to-cis isomerization in the azobenzene moiety, which causes a conformational change in the upper molecular layers of the thin films. These changes originate a hydrophobic to comparatively hydrophilic transformation of the surface. The reversible wettability of the surface results from the cis/trans photo and thermal isomerization. The UV-vis absorption spectra, as well as contact angle measurements with UV irradiation, clearly support the understanding of the phenomenon. This type of surface design enables the amplification of molecular level conformational transitions to macroscopic changes in interface properties using the means of isomerism. This opens new opportunities in surface engineering using eco-friendly cellulose manipulation.

Free-standing urethane/urea elastomer films undoped and doped with ferro-nano-particles.

We report on an experimental study of the structures presented by urethane/urea elastomeric films without and with ferromagnetic nanoparticles incorporated. The study is made by using the X-ray diffraction, nuclear magnetic resonance (NMR), optical, atomic and magnetic force (MFM) microscopy techniques, and mechanical assays. The structure of the elastomeric matrix is characterized by a distance of 0.46 nm between neighboring molecular segments, almost independent on the stretching applied. The shear casting performed in order to obtain the elastomeric films tends to orient the molecules parallel to the flow direction thus introducing anisotropy in the molecular network which is reflected on the values obtained for the orientational order parameter and its increase for the stretched films. In the case of nanoparticles-doped samples, the structure remains nearly unchanged although the local order parameter is clearly larger for the undoped films. NMR experiments evidence modifications in the molecular network local ordering. Micrometer size clusters were observed by MFM for even small concentration of magnetic particles.

Single-crystal study on the heavy-fermion antiferromagnet UZn12.

Millimetre size UZn(12) single crystals were grown by the high temperature solution growth method using zinc as the solvent. Single-crystal x-ray diffraction data confirm that this compound crystallizes in the hexagonal high temperature form of SmZn(12) (S.G. P6/mmm) and points to a U(1.01(1))Zn(11.7(1)) stoichiometry for the crystals, with ∼ 4% of the U atoms being located at the 2c site due to the partial substitution of 4h Zn pairs. UZn(12) orders antiferromagnetically at T(N) = 5.0(2) K, and the magnetization and resistivity measurements suggest that the magnetic moments are confined within the a-b plane. The Sommerfeld coefficient, derived from the paramagnetic region by the standard method, is γ(p)≈200 mJ (mol K(2))( - 1), which definitely classifies UZn(12) as a moderate heavy-fermion system. The heavy-fermion character of UZn(12) is also manifested in the overall shape of temperature-dependent electrical resistivity that is dominated by a single-ion Kondo effect at high temperatures and coherent Kondo scattering at low temperatures. The paramagnetic magnetoresistivity isotherms can be fairly well superimposed onto each other using Schlottmann's scaling for the single-ion Kondo model, as expected for a Kondo system.

Computational modeling of lumbar disc degeneration before and after spinal fusion.

BACKGROUND: Advancing age and degeneration frequently lead to low back pain, which is the most prevalent musculoskeletal disorder worldwide. Degenerative changes in intervertebral discs and musculo-ligamentous incapacity to compensate sagittal imbalance are typically amongst the sources of instability, with spinal fusion techniques being the main treatment options to relieve pain. The aims of this work were to: (i) assess the link between ligament degeneration and spinal instability by determining the role of each ligament per movement, (ii) evaluate the impact of disc height reduction in degenerative changes, and (iii) unveil the most advantageous type of posterior fixation in Oblique Lumbar Interbody Fusion to prevent adjacent disc degeneration. METHODS: Two L3-L5 finite element models were developed, being the first in healthy condition and the second having reduced L4-L5 height. Different degrees of degeneration were tested, combined with different fixation configurations for Oblique Lumbar Interbody Fusion. FINDINGS: Facet capsular ligament and anterior longitudinal ligament were the most influential ligaments for spinal stability, particularly with increasing degeneration and disc height reduction. Pre-existent degeneration had lower influence than the fusion procedure for the risk of adjacent disc degeneration, being the highest stability and minimal degeneration achieved with bilateral fixation. Right unilateral fixation was more suited to reduce disc stress than left unilateral fixation. INTERPRETATION: Bilateral fixation is the best option to stabilize the spinal segment, but unilateral right fixation may suffice. This has direct implications for clinical practice, and the extension to a population-based study will allow for more efficient fusion surgeries.

Relevance of BCAR4 in tamoxifen resistance and tumour aggressiveness of human breast cancer.

BACKGROUND: Breast cancer anti-oestrogen resistance 4 (BCAR4) was identified in a search for genes involved in anti-oestrogen resistance in breast cancer. We explored whether BCAR4 is predictive for tamoxifen resistance and prognostic for tumour aggressiveness, and studied its function. METHODS: BCAR4 mRNA levels were measured in primary breast tumours, and evaluated for association with progression-free survival (PFS) and clinical benefit in patients with oestrogen receptor (ERα)-positive tumours receiving tamoxifen as first-line monotherapy for advanced disease. In a separate cohort of patients with lymph node-negative, ERα-positive cancer, and not receiving systemic adjuvant therapy, BCAR4 levels were evaluated for association with distant metastasis-free survival (MFS). The function of BCAR4 was studied with immunoblotting and RNA interference in a cell model. RESULTS: Multivariate analyses established high BCAR4 mRNA levels as an independent predictive factor for poor PFS after start of tamoxifen therapy for recurrent disease. High BCAR4 mRNA levels were associated with poor MFS and overall survival, reflecting tumour aggressiveness. In BCAR4-expressing cells, phosphorylation of v-erb-b2 erythroblastic leukaemia viral oncogene homolog (ERBB)2, ERBB3, and their downstream mediators extracellular signal-regulated kinase 1/2 and v-akt murine thymoma viral oncogene homolog (AKT) 1/2, was increased. Selective knockdown of ERBB2 or ERBB3 inhibited proliferation, confirming their role in BCAR4-induced tamoxifen resistance. CONCLUSION: BCAR4 may have clinical relevance for tumour aggressiveness and tamoxifen resistance. Our cell model suggests that BCAR4-positive breast tumours are driven by ERBB2/ERBB3 signalling. Patients with such tumours may benefit from ERBB-targeted therapy.

The characterization of Listeria spp. isolated from food products and the food-processing environment.

AIM: To enhance the information pertaining to the epidemiology of a collection of 378 Listeria spp. isolates obtained from several food-processing plants in Ireland over a 3-year period (2004-2007). METHODS AND RESULTS: The collection was characterized by pulsed-field gel electrophoresis (PFGE). The most prevalent pulse-type was PFGE profile I (n=14·5%) that consisted mainly of environmental Listeria spp. samples. Serotyping of 145 Listeria monocytogenes isolates was performed. The most common serovar was 1/2a and comprised 57·4% (n=77) of the L. monocytogenes collection. The other serovars were as follows: 4b (14·1%, n=19), 1/2b (9·7%, n=13), 4c (4·4%, n=6) and 1/2c (6·7%, n=9), respectively. Eleven isolates were identified as non-Listeria spp., the remaining ten L. monocytogenes isolates were nontypeable. The antimicrobial susceptibility testing revealed the antibiotic that isolates displayed the most resistance to was gentamicin (5%) followed by sulfamethoxazole-trimethoprim (2%), tetracycline and ciprofloxacin (1·5%). CONCLUSIONS: The subtyping has indicated the diversity of the Listeria spp. The presence of serotype 1/2a, 1/2b and 4b in both raw and cooked ready-to-eat food products is a public health concern, as these serotypes are frequently associated with foodborne outbreaks and sporadic cases of human listeriosis. In addition, the emergence of antimicrobial-resistant L. monocytogenes isolates could have serious therapeutic consequences. SIGNIFICANCE AND IMPACT OF STUDY: The molecular subtyping and the further characterization of these isolates may be valuable particularly in the context of a suspected common source outbreak in the future.

Conversion of MDF wastes into a char with remarkable potential to remove Food Red 17 dye from aqueous effluents.

Medium density fiberboard (MDF) wastes were converted into an efficient char able to uptake Food Red 17 dye (FR17) from colored effluents. The yield of the pyrolysis process, in terms of char, was 29%. The produced char presented micro and mesoporous, with surface area of 218.8 m2 g-1 and total pore volume of 0.122 cm3 g-1. Regarding to the FR17 adsorption, removal percentages of 90% were found at pH 2 and using 0.5 g L-1 of char. Pseudo-first and pseudo-second order models were adequate to represent the adsorption kinetic profile, being the equilibrium reached within 20 min. Freundlich model was selected to represent the equilibrium data. The maximum adsorption capacity was 210 mg g-1. The adsorption of FR17 on the char was endothermic and physical in nature. The char was efficient for 8 adsorption-desorption cycles, maintaining the same adsorption capacity. In brief, this work demonstrated a useful practice in terms of cleaner production. It was possible add value to MDF wastes, generating an efficient and reusable adsorbent to treat colored effluents containing FR 17 dye.

Ferromagnetism induced in rutile single crystals by argon and nitrogen implantation.

The magnetic properties of Ar- and N-implanted single crystalline TiO(2) rutile were studied and correlated with the induced disorder in order to clarify the influence of defects in the magnetic behaviour. Nominal fluences of 1 × 10(17) and 2 × 10(17) cm(-2) and an implantation energy of 100 keV were used. The as-implanted single crystals exhibited ferromagnetic behaviour up to 380 K. Annealing at 1073 K induced recovery of the lattice structure and the decrease of the ferromagnetic moment in the case of Ar-implanted samples, but the magnetic moment did not change significantly for the samples implanted with nitrogen. No impurities, other than the implanted species were detected and consequently the ferromagnetic behaviour is attributed to defects created during implantation, which in the case of nitrogen remained in the lattice even after partial recovery of the structure.

Study of micro and nano surface structures from UV irradiated urethane/urea elastomers.

In this work we address new results obtained with a thin free standing flexible film (approximately 120 microm) of a urethane/urea copolymer related to the formation of micro and nano size structures [M.H. Godinho, A.C. Trindade, J.L. Figueirinhas, L.V. Melo, P. Brogueira, Synthetic Metals, 147(1-3), 209 (2004); M.H. Godinho, A.C. Trindade, J.L. Figueirinhas, L.V. Melo, P. Brogueira, Molecular Crystals and Liquid Crystals (2005)]. The copolymer was synthesized from a polypropylene oxide-based prepolymer with three isocyanate terminal groups (PU) and polybutadienediol (PBDO) with PBDO content of 40% wt. After casting and curing the film was cut into different samples and each exposed to UV radiation for different periods of time; 23, 25, 26, 31 and 49 h (lambda=254 nm) and later extracted with toluene and dried. The dried films were then studied by polarising optical microscopy (POM), small angle light scattering (SALS) and the surfaces exposed to UV radiation analyzed by means of atomic force microscopy (AFM). Before extraction with toluene a nanometer-flat surface, characterized by a mean roughness value Ra=0.59 nm, was obtained. Depending on exposure time to UV radiation and after extraction with toluene a corrugated surface, with features mum-sized in all axes, resulting in an increase of the overall mean roughness value to Ra=50.7 nm, starts to develop after 25 h of exposure time. This work gives evidence of the non-monotonous time behavior of the wrinkled surface growth that develops under the action of ultraviolet radiation. As the exposure time increases the free-standing films directly exposed surfaces show a decreasing density of the structures observed and an increasing characteristic peak-to-valley height. The peak-to-valley height measured for samples exposed for 23, 25, 26, 31 and 49 h, respectively 193, 383, 381, 1550 and 2039 nm and the corresponding mean roughness values are Ra=50.7 nm, 105.4, 116.8, 438.3 and 515.4 nm, respectively. Between 26 and 31 h exposure time a leap in both values, peak-to-valley and Ra, was observed. The sudden increase in these values is correlated to fabrication of wrinkles by uniaxially stretching PU/PBDO elastomer films.

Performance of rotary kiln reactor for the elephant grass pyrolysis.

The influence of process conditions (rotary speed/temperature) on the performance of a rotary kiln reactor for non-catalytic pyrolysis of a perennial grass (elephant grass) was investigated. The product yields, the production of non-condensable gases as well as the biochar properties were evaluated. The maximum H2 yield was close to that observed for catalytic pyrolysis processes, while the bio-oil yield was higher than reported for pyrolysis of other biomass in rotary kiln reactors. A H2/CO ratio suitable for Fischer-Tropsch synthesis (FTS) was obtained. The biochars presented an alkaline pH (above 10) and interesting contents of nutrients, as well as low electrical conductivity, indicating a high potential as soil amendment.

CREB is cleaved by caspases during neural cell apoptosis.

Programmed cell death, or apoptosis, is a tightly regulated process mediated by selective cleavage of proteins by caspases, resulting in ordered destruction of the cell. In addition to structural proteins, proteins that mediate anti-apoptotic signal transduction are also substrates; their destruction eliminates potential futile attempts to escape execution. We asked whether cAMP response element binding protein (CREB), a transcription factor that mediates nerve growth factor (NGF) survival signals, is a target for caspases during apoptosis. CREB was specifically cleaved by caspases in neuroblastoma extracts, and in cells induced to undergo apoptosis by staurosporine. The destruction of CREB eliminates a key factor that could reverse apoptosis.

Umbilical cord blood processing: volume reduction and recovery of CD34+ cells.

One of the main problems for the establishment of umbilical cord blood (UCB) banks is the storage space needed for the frozen samples. The aim of this study was to find a method of reducing the volume of UCB units without major losses of the haematopoietic progenitor-CD34+ cells. The UCB was collected into a triple blood bag system, in which the anti-coagulant had been previously adjusted. The blood bag was first centrifuged for red cell depletion followed by a second centrifugation for plasma reduction. At this point, the main bag containing the white blood cell (WBC) rich fraction "buffy coat' (BC) and the "waste bag' were sealed and detached. Haematologic cell counts and CD34+ cell quantification were done in whole blood and in the isolated fractions. The average volume of the 19 UCB samples processed was 103 ml. Separation by centrifugation led to a mean volume reduction of 56% with red cell depletion of 59%. The white blood cell recovery was of 72% with a significant CD34+ cell recovery of 87%. This seems a promising method for cord blood volume reduction and enrichment of CD34+ cells.

Analysis of surface markers on CD34+ cells, isolated from cord blood and G-CSF primed peripheral blood.

We report a comparative study of the expression of multilineage and adhesion molecules on CD34+ cells isolated from human umbilical cord blood (CB) and G-CSF-mobilized peripheral blood progenitor cells (PBPC) from healthy volunteers. The major difference found between the two sources of CD34+ populations was the expression of CD54 molecule, which was higher in CB in comparison to PBPC.

Morphologic and anthropometric characteristics of high level Dutch korfball players.

In this study a morphologic and anthropometric characterisation of Dutch korfball players (N = 36) is performed. Data, compared with those of other sports populations, showed that (1) korfball athletes are smaller and lighter than basketball and volleyball players but heavier and taller than other team-sport players; (2) korfball players have less relative body fat, more lean body mass, more limb fat, and less or similar trunk fat than the other athletes. (3) Male korfball players presented a somatotype (1.9-4.4-3.4) similar to endurance athletes and an endomorphic value lower than or similar to the other athletes. (4) The only apparent similarity between female korfball somatotype (3.2-4.0-2.8) and other athletes' somatotypes is the dominance of mesomorphy.