Electron energy-loss spectroscopic tomography of FexCo(3-x)O4 impregnated Co3O4 mesoporous particles: unraveling the chemical information in three dimensions.

Electron energy-loss spectroscopy-spectrum image (EELS-SI) tomography is a powerful tool to investigate the three dimensional chemical configuration in nanostructures. Here, we demonstrate, for the first time, the possibility to characterize the spatial distribution of Fe and Co cations in a complex FexCo(3-x)O4/Co3O4 ordered mesoporous system. This hybrid material is relevant because of the ferrimagnetic/antiferromagnetic coupling and high surface area. We unambiguously prove that the EELS-SI tomography shows a sufficiently high resolution to simultaneously unravel the pore structure and the chemical signal.

Electrochemically synthesized amorphous and crystalline nanowires: dissimilar nanomechanical behavior in comparison with homologous flat films.

The effects of constrained sample dimensions on the mechanical behavior of crystalline materials have been extensively investigated. However, there is no clear understanding of these effects in nano-sized amorphous samples. Herein, nanoindentation together with finite element simulations are used to compare the properties of crystalline and glassy CoNi(Re)P electrodeposited nanowires (ϕ ≈ 100 nm) with films (3 µm thick) of analogous composition and structure. The results reveal that amorphous nanowires exhibit a larger hardness, lower Young's modulus and higher plasticity index than glassy films. Conversely, the very large hardness and higher Young's modulus of crystalline nanowires are accompanied by a decrease in plasticity with respect to the homologous crystalline films. Remarkably, proper interpretation of the mechanical properties of the nanowires requires taking the curved geometry of the indented surface and sink-in effects into account. These findings are of high relevance for optimizing the performance of new, mechanically-robust, nanoscale materials for increasingly complex miniaturized devices.

Nanostructured Ti-Zr-Pd-Si-(Nb) bulk metallic composites: Novel biocompatible materials with superior mechanical strength and elastic recovery.

The microstructure, mechanical behaviour, and biocompatibility (cell culture, morphology, and cell adhesion) of nanostructured Ti45 Zr15 Pd35- x Si5 Nbx with x = 0, 5 (at. %) alloys, synthesized by arc melting and subsequent Cu mould suction casting, in the form of rods with 3 mm in diameter, are investigated. Both Ti-Zr-Pd-Si-(Nb) materials show a multi-phase (composite-like) microstructure. The main phase is cubic ß-Ti phase (Im3m) but hexagonal α-Ti (P63/mmc), cubic TiPd (Pm3m), cubic PdZr (Fm3m), and hexagonal (Ti, Zr)5 Si3 (P63/mmc) phases are also present. Nanoindentation experiments show that the Ti45 Zr15 Pd30 Si5 Nb5 sample exhibits lower Young's modulus than Ti45 Zr15 Pd35 Si5 . Conversely, Ti45 Zr15 Pd35 Si5 is mechanically harder. Actually, both alloys exhibit larger values of hardness when compared with commercial Ti-40Nb, (HTi-Zr-Pd-Si ≈ 14 GPa, HTi-Zr-Pd-Si-Nb ≈ 10 GPa and HTi-40Nb ≈ 2.7 GPa). Concerning the biological behaviour, preliminary results of cell viability performed on several Ti-Zr-Pd-Si-(Nb) discs indicate that the number of live cells is superior to 94% in both cases. The studied Ti-Zr-Pd-Si-(Nb) bulk metallic system is thus interesting for biomedical applications because of the outstanding mechanical properties (relatively low Young's modulus combined with large hardness), together with the excellent biocompatibility.

Electrodeposition of magnetic, superhydrophobic, non-stick, two-phase Cu-Ni foam films and their enhanced performance for hydrogen evolution reaction in alkaline water media.

Two-phase Cu-Ni magnetic metallic foams (MMFs) with tunable composition have been prepared by electrodeposition taking advantage of hydrogen co-evolution as a source of porosity. It is observed that Ni tends to deposit inside the porous network defined by the Cu building blocks. Contact angle measurements reveal that the prepared porous films show a remarkable superhydrophobicity (contact angle values larger than 150°) and a non-sticking property to aqueous droplets. This behavior is predominately ascribed to the morphology of the films - hierarchical micro/nanoporosity, wall thickness, and spatial arrangement. The electrochemical activity and stability towards hydrogen evolution reaction of the Cu-Ni MMFs has been investigated by cyclic voltammetry in 1 M KOH at 298 K, and the optimal Ni content is found to be 15 at%. Furthermore, all the foam-like films exhibit ferromagnetic behaviour due to the presence of the Ni-rich phase, with coercivity values ranging from 114 Oe to 300 Oe. From the technological point of view, the Cu-Ni MMFs are promising candidates for magnetically-actuated micro/nano-electromechanical systems (MEMS/NEMS) and micro/nanorobotic platforms with a large surface-area to volume ratio or in magnetic sensors or separators.

One-pot electrosynthesis of multi-layered magnetic metallopolymer nanocomposites.

Researchers have been investigating various methodologies for fabricating well-defined, homogenous composites consisting of nanoparticles (NPs) dispersed in a matrix. The main challenges are to prevent particle agglomerations during fabrication and to obtain nanoparticles whose size distribution could be tuned on demand. One of the methods that can provide these features is electrodeposition. We report for the first time the fabrication of a thin magnetic multilayer nanocomposite film by electrodeposition from one bath containing both a monomer and metal salts. Cobalt and cobalt-nickel NPs were deposited on conductive polymer polypyrrole thin films using different electrodeposition potentials and times. Multilayer nanocomposite films were fabricated by subsequent electrodeposition of polymer and nanoparticle layers. Scanning electron microscopy analysis showed that a wide range of NPs (70-230 nm) could be synthesized by manipulating growth potentials and times. The cobalt-nickel NPs were found to contain hexagonal close-packed (hcp) and face-centered cubic (fcc) phases based on X-ray diffraction and selected area electron diffraction. Magnetic measurements proved that both the single and the multi-layered nanocomposites were magnetic at room temperature.

In vitro biocompatibility assessment of Ti40Cu38Zr10Pd12 bulk metallic glass.

The use of biocompatible materials has attained an increasing importance for tissue regeneration and transplantation. The excellent mechanical and corrosion properties of Ti40Cu38Zr10Pd12 bulk metallic glass (BMG) turn it into a potential candidate for its use in orthopaedic implants. Before being considered as a biomaterial, some biological parameters must be taken into account. In this study,mouse preosteoblasts were cultured in the presence or absence of the alloy at different times (24 h, 7 and 21 days) and no differences in cell viability were detected.Moreover, cells were able to adhere to the alloy surface by establishing focal contacts, and displayed a flattened polygonal morphology. After 14 days in culture, differentiation into osteoblasts was observed. Besides, the amount of Cu ions released and their potential toxic effects were analyzed, showing that the amount of Cu released did not increase cell death. Finally, the low levels of inflammatory cytokines secreted by THP-1 differentiated macrophages exposed to the alloy suggest the absence of an immunogenic response to the alloy. In conclusion, in vitro studies indicate that the Ti40Cu38Zr10Pd12 BMG could be considered as a biomaterial to be used in orthopaedic implants.

White-light photoluminescence and photoactivation in cadmium sulfide embedded in mesoporous silicon dioxide templates studied by confocal laser scanning microscopy.

SBA-15 and SBA-16 silica templates have been infiltrated with CdS by means of nanocasting using a hybrid precursor. The morphology and structure of both the SiO2@CdS nanocomposites and the silica-free CdS replicas have been characterized. The three-dimensional nanocrystalline CdS networks embedded in SBA-15 and SBA-16 silica templates exhibit broad photoluminescence (PL) spectra over the entire visible range, together with enhanced PL intensity compared to silica-free CdS replicas. These effects result from the role silica plays in passivating the surface of the CdS mesostructures. Furthermore, photoactivation is eventually observed during continuous illumination because of both structural and chemical surface modifications. Owing to this combination of properties, these materials could be appealing for solid-state lighting, where ultra-bright near-white PL emission is indispensable.

On the biodegradability, mechanical behavior, and cytocompatibility of amorphous Mg72 Zn23 Ca5 and crystalline Mg70 Zn23 Ca5 Pd2 alloys as temporary implant materials.

The evolution of microstructure and mechanical properties of almost fully amorphous Mg(72) Zn(23) Ca(5) and crystalline Mg(70) Zn(23) Ca(5) Pd(2) alloys during immersion in Hank's balanced salt solution (HBSS), as well as their cytocompatibility, are investigated in order to assess the feasibility of both materials as biodegradable implants. Though the crystalline Mg(70) Zn(23) Ca(5) Pd(2) sample shows lower wettability and more positive corrosion potential, this sample degrades much faster upon incubation in HBSS as a consequence of the formation of micro-galvanic couples between the nobler Pd-rich dendrites and the surrounding phases. After 22-h immersion, the concentration of Mg ions in the HBSS medium containing the Mg(70) Zn(23) Ca(5) Pd(2) sample is six times larger than for Mg(72) Zn(23) Ca(5) . Due to the Zn enrichment and the incipient porosity, the mechanical properties of the Mg(72) Zn(23) Ca(5) sample improve within the first stages of biodegradation (i.e., hardness increases while the Young's modulus decreases, thus rendering an enhanced wear resistance). Cytocompatibility studies reveal that neither Mg(72) Zn(23) Ca(5) nor Mg(70) Zn(23) Ca(5) Pd(2) are cytotoxic, although preosteoblast cell adhesion is to some extent precluded, particularly onto the surface of Mg(70) Zn(23) Ca(5) Pd(2) , because of the relatively high hydrophobicity. Because of their outstanding properties and their time-evolution, the use of the Pd-free alloy in temporary implants such as screws, stents, and sutures is envisioned.

Improved mechanical performance and delayed corrosion phenomena in biodegradable Mg-Zn-Ca alloys through Pd-alloying.

The influence of partial substitution of Mg by Pd on the microstructure, mechanical properties and corrosion behaviour of Mg(72-x)Zn(23)Ca(5)Pd(x) (x=0, 2 and 6 at.%) alloys, synthesized by copper mould casting, is investigated. While the Mg(72)Zn(23)Ca(5) alloy is mainly amorphous, the addition of Pd decreases the glass-forming ability, thus favouring the formation of crystalline phases. From a mechanical viewpoint, the hardness increases with the addition of Pd, from 2.71 GPa for x=0 to 3.9 GPa for x=6, mainly due to the formation of high-strength phases. In turn, the wear resistance is maximized for an intermediate Pd content (i.e., Mg(70)Zn(23)Ca(5)Pd(2)). Corrosion tests in a simulated body fluid (Hank's solution) indicate that Pd causes a shift in the corrosion potential towards more positive values, thus delaying the biodegradability of this alloy. Moreover, since the cytotoxic studies with mouse preosteoblasts do not show dead cells after culturing for 27 h, these alloys are potential candidates to be used as biomaterials.

Enhanced mechanical properties and in vitro corrosion behavior of amorphous and devitrified Ti40Zr10Cu38Pd12 metallic glass.

The effects of annealing treatments on the microstructure, elastic/mechanical properties, wear resistance and corrosion behavior of rod-shaped Ti40Zr10Cu38Pd12 bulk glassy alloys, synthesized by copper mold casting, are investigated. Formation of ultrafine crystals embedded in an amorphous matrix is observed for intermediate annealing temperatures, whereas a fully crystalline microstructure develops after heating to sufficiently high temperatures. The glassy alloy exhibits large hardness, relatively low Young's modulus, good wear resistance and excellent corrosion behavior. Nanoindentation measurements reveal that the sample annealed in the supercooled liquid region exhibits a hardness value of 9.4 GPa, which is 20% larger than in the completely amorphous state and much larger than the hardness of commercial Ti-6Al-4V alloy. The Young's modulus of the as-cast alloy (around 100 GPa, as determined from acoustic measurements) increases only slightly during partial devitrification. Finally, the anticorrosion performance of the Ti40Zr10Cu38Pd12 alloy in Hank's solution has been shown to ameliorate as crystallization proceeds and is roughly as good as in the commercial Ti-6Al-4V alloy. The outstanding mechanical and corrosion properties of the Ti40Zr10Cu38Pd12 alloy, both in amorphous and crystalline states, are appealing for its use in biomedical applications.

Structural and magnetic characterization of batch-fabricated nickel encapsulated multi-walled carbon nanotubes.

We report on the growth and fabrication of Ni-filled multi-walled carbon nanotubes (Ni-MWNTs) with an average diameter of 115 nm and variable length of 400 nm-1 µm. The Ni-MWNTs were grown using template-assisted electrodeposition and low pressure chemical vapor deposition (LPCVD) techniques. Anodized alumina oxide (AAO) templates were fabricated on Si using a current controlled process. This was followed by the electrodeposition of Ni nanowires (NWs) using galvanostatic pulsed current (PC) electrodeposition. Ni NWs served as the catalyst to grow Ni-MWNTs in an atmosphere of H2/C2H2 at a temperature of 700 °C. Time dependent depositions were carried out to understand the diffusion and growth mechanism of Ni-MWNTs. Characterization was carried out using scanning electron microscopy (SEM), focused ion beam (FIB) milling, transmission electron microscopy (TEM), Raman spectroscopy and energy dispersive x-ray spectroscopy (EDX). TEM analysis revealed that the Ni nanowires possess a fcc structure. To understand the effects of the electrodeposition parameters, and also the effects of the high temperatures encountered during MWNT growth on the magnetic properties of the Ni-MWNTs, vibrating sample magnetometer (VSM) measurements were performed. The template-based fabrication method is repeatable, efficient, enables batch fabrication and provides good control on the dimensions of the Ni-MWNTs.

Water vapor detection with individual tin oxide nanowires.

Individual tin oxide nanowires (NWs), contacted to platinum electrodes using focused ion beam assisted nanolithography, were used for detecting water vapor (1500-32 000 ppm) in different gaseous environments. Responses obtained in synthetic air (SA) and nitrogen atmospheres suggested differences in the sensing mechanism, which were related to changes in surface density of the adsorbed oxygen species in the two cases. A model describing the different behaviors has been proposed together with comparative evaluation of NW responses against sensors based on bulk tin oxide. The results obtained on ten individual devices (tested >6 times) revealed the interfering effect of water in the detection of carbon monoxide and illustrated the intrinsic potential of nanowire-based devices as humidity sensors. Investigations were made on sensitivity, recovery time and device stability as well as surface-humidity interactions. This is the first step towards fundamental understanding of single-crystalline one-dimensional (1D) tin oxide nanostructures for sensor applications, which could lead to integration in real devices.

Portable microsensors based on individual SnO2 nanowires.

Individual SnO(2) nanowires were integrated in suspended micromembrane-based bottom-up devices. Electrical contacts between the nanowires and the electrodes were achieved with the help of electron- and ion-beam-assisted direct-write nanolithography processes. The stability of these nanomaterials was evaluated as function of time and applied current, showing that stable and reliable devices were obtained. Furthermore, the possibility of modulating their temperature using the integrated microheater placed in the membrane was also demonstrated, enabling these devices to be used in gas sensing procedures. We present a methodology and general strategy for the fabrication and characterization of portable and reliable nanowire-based devices.

Neoadjuvant radiation and chemotherapy in rectal cancer does not increase postoperative complications.

BACKGROUND AND AIMS: Neoadjuvant radiation and chemotherapy in rectal cancer reduces local recurrences and increases the rate of conservative sphincter surgery. However, an increase in postoperative morbidity and mortality has also been observed. This study analyzed the operative difficulty and postoperative complications in patients with this treatment. PATIENTS AND METHODS: Retrospective review of 103 patients with rectal cancer, divided into two groups: group A, 53 patients undergoing preoperative radiotherapy with 45 Gy combined with chemotherapy, and group B, 50 patients with rectal cancer who received surgery after diagnosis. Both groups were homogeneous. The two groups were compared for both technical difficulty, using intraoperative data and rate of complications. RESULTS: There were no statistically significant differences between the two groups with regard to intraoperative or postoperative data. In group A there were 20 complications in 17 patients (32%) and in group B 22 complications in 19 patients (38%). The rates of perineal wound infection were similar. The percentage of anastomotic leaks was higher in group A. A greater number of anterior resections was performed in group A. CONCLUSION: Preoperative radiation and chemotherapy in rectal cancer does not increase postoperative complications and increases the rate of sphincter-preserving surgery.

Índice de sustitución como indicador de calidad en cirugía mayor ambulatoria. Evolución anual en un servicio de cirugía / The substitution index as an indicators of quality of care in major ambulatory surgery: Annual evolution in a surgery department

Fundamento: El índice de sustitución (IS) es uno de los indicadores utilizados para monitorizar la calidad de los programas de cirugía mayor ambulatoria (CMA). El objetivo de nuestro trabajo es estudiar la evolución en los últimos años de dicho índice en nuestro servicio de cirugía. Métodos: En el período 1995-2000 fueron intervenidos 5.675 pacientes por patologías incluidas en los programas de CMA. El 37,8 por ciento de los pacientes fueron intervenidos sin ingreso. Se analiza el IS anual para cada enfermedad. Resultados: Observamos una evolución ascendente del IS para cada enfermedad, alcanzando en el año 2000 cifras del 93 por ciento para enfermedades como el sinus pilonidal. Conclusión: El IS como medida del impacto de la CMA en nuestro servicio ha presentado un incremento anual para la mayor parte de los procesos hasta equipararse con los estándares establecidos actualmente (AU)

La quimioterapia y la radioterapia neoadyuvante en el cáncer de recto incrementan las tasas de cirugía conservadora de esfínteres, sin aumentar la dificultad técnica de la intervención ni las complicaciones postoperatorias / Neoadjuvant chemotherapy and radiation therapy in rectal cancer increases the rate of sphincter conservation without increasing the technical difficulty of the intervention or postoperative complications

Introducción. La radioquimioterapia neoadyuvante en el cáncer de recto disminuye las recidivas locales y algunos autores comunican un aumento de la supervivencia, también se ha observado un aumento de la morbimortalidad postoperatoria. El objetivo de este estudio es analizar la dificultad operatoria y las complicaciones postoperatorias en los pacientes con radioquimioterapia preoperatoria. Pacientes y método. Se estudian 103 pacientes intervenidos de cáncer de recto entre enero de 1995 y diciembre de 1999, divididos en dos grupos: grupo A, formado por 53 pacientes sometidos a radioterapia preoperatoria con 45 Gy (1,8 Gy/día durante 25 días), junto a quimioterapia con 5-fluorouracilo y ácido folínico (la cirugía se realizó 4-6 semanas después de la finalización del tratamiento), y grupo B, compuesto por 50 pacientes con cáncer de recto a los que se practicó la cirugía tras el diagnóstico. Ambos grupos son homogéneos en los datos preoperatorios analizados. Se compara entre los dos grupos la dificultad técnica mediante datos intraoperatorios, así como la tasa de complicaciones. Resultados. No existen diferencias estadísticamente significativas entre los dos grupos en cuanto a los datos intraoperatorios ni postoperatorios evaluados. En el grupo A existen 20 complicaciones en 17 pacientes (32 por ciento), mientras que en el grupo B existen 22 complicaciones en 19 pacientes (38 por ciento). La tasa de infección de la herida perineal fue similar en los dos grupos: el 9,4 por ciento en el grupo A frente al 10 por ciento en el grupo B. El porcentaje de fugas anastomóticas fue mayor en el grupo A (5,7 por ciento) que en el grupo B (2 por ciento), diferencia sin significación estadística. En el grupo de radioquimioterapia se realizaron un mayor número de resecciones anteriores (75 por ciento) que en el grupo B (60 por ciento). Conclusión. El uso de la radioquimioterapia preoperatoria en el cáncer de recto no aumenta la incidencia de complicaciones postoperatorias y aumenta la tasa de cirugía conservadora de esfínteres (AU)

Cytohistologic correlation of nuclear grade in breast carcinoma.

OBJECTIVE: To compare the nuclear grade (NG) in cytologic material (CNG) obtained from breast fine needle aspiration biopsies (FNABs) with the NG observed in surgical biopsies (BNG) of the same tumors. STUDY DESIGN: The study group consisted of 135 breast carcinomas with both FNAB and biopsy. Most of them were invasive ductal carcinomas. Cytologic aspirates and tissue sections were graded simultaneously by the three authors using a multiheaded microscope. Fisher's modification of Black's nuclear grading scheme was used. RESULTS: There was agreement between CNG and BNG in 70.37% of tumors. The percentage coincidence was slightly greater for NG 3. CONCLUSION: Nuclear grade can be easily established on FNAB. The lack of correlation (29.63%) may have been due to tumor heterogeneity and observer subjectivity when assigning nuclear grade.

Carcinoembryonic antigen expression in stages I and II breast cancer: its relationship with clinicopathologic factors.

Carcinoembryonic antigen (CEA) has been detected by immunohistochemistry in breast carcinoma, but its relationship with prognosis is still unclear. This difficulty may be because of the great variety of antibodies used for its determination. In the present study, 271 stages I and II breast carcinomas are analyzed by immunohistochemistry, using T84.66 antibody, a well-known highly specific CEA antibody. The results show that CEA expression was not associated with any of the clinicopathologic factors analyzed. Factors associated with disease-free survival (DFS) after univariate logistic regression analyses were tumor size smaller than 2 cm (P = .01), lymph node free of metastases (P = .0000), low nuclear grade (P = .007), absence of c-erbB-2 overexpression (P = .02), and bcl-2 (P = .005) and CEA expression (P = .005), whereas those significantly associated with a better overall survival (OS) were tumor size small than 2 cm (P = .002), lymph node free of metastases (P = .0001), low nuclear grade (P = .01), low histological grade (P = .02), absence of c-erbB-2 overexpression (P = .002) and bcl-2 expression (P = .01). After multivariate stepwise regression analysis, lymph node free of metastases (P = .0000), CEA expression (P = .001), absence of c-erbB-2 overexpression (P = .01), and bcl-2 expression (P = .01) were found to be independent factors associated with DFS, whereas lymph node free of metastases (P = .0000), tumor size smaller than 2 cm (P = .0000), and absence of c-erbB-2 overexpression (P = .004) were associated with a better OS. These results show that immunohistochemical detection of CEA with the antibody T84.66 may be useful as an additional factor in establishing breast cancer prognosis.

Diagnostic value of p53 protein in the study of serous effusions.

The differential diagnosis between neoplastic and reactive mesothelial cells is one of the most frequent problems in the study of serous effusions. We assessed the utility of the immunohistochemical determination of p53 protein as a marker of malignancy in 34 embedded blocks of neoplastic fluids and 30 nonneoplastic effusions. Eleven (32.4%) of the tumor fluids were positive for this antibody, while all the nonneoplastic fluids were negative. A specificity of 100% and a sensitivity of 59% were observed. The immunohistochemical determination of p53 protein seems to be helpful in the differential diagnosis of effusions; its principal limitation is its relatively low sensitivity.