Luminescent and magnetic [TbEu] 2D metal-organic frameworks.

We present the synthesis, through a simple, microwave-assisted method, of lanthanoid-based 2D metal-organic frameworks (MOFs) of general formula [LnxLn'1-x(MeCOO)(PhCOO)2], including homonuclear compounds (x = 1), LnEu, Tb, and heterometallic compounds, [TbEu]. The crystalline material is formed by neutral nanosheets held together by van der Waals interactions, which can be easily exfoliated by sonication. Photoluminescent emission in the visible range was observed for all of the synthesized 2D MOF compounds via excitation of the ligand, showing benzoates are efficient antenna ligands. Efficient energy transfer from Tb → Eu was observed in the heterometallic [TbEu] compounds, which could potentially perform as luminescent thermometers. Inks containing nanosheets of 2D MOFs exfoliated in solution were prepared, and luminescent prints of Tb and Eu 2D MOFs on paper were made to show the possible application for anticounterfeiting. Frequency-dependent ac susceptibility results show the occurrence of slow magnetic relaxation in [TbEu] compounds through direct relaxation mechanisms, affected by bottleneck effect. A slowing down of the relaxation time is observed as the Eu/Tb ratio increases.

The Far Ultra-Violet imager on the ICON mission.

ICON Far UltraViolet (FUV) imager contributes to the ICON science objectives by providing remote sensing measurements of the daytime and nighttime atmosphere/ionosphere. During sunlit atmospheric conditions, ICON FUV images the limb altitude profile in the shortwave (SW) band at 135.6 nm and the longwave (LW) band at 157 nm perpendicular to the satellite motion to retrieve the atmospheric O/N2 ratio. In conditions of atmospheric darkness, ICON FUV measures the 135.6 nm recombination emission of O+ ions used to compute the nighttime ionospheric altitude distribution. ICON Far UltraViolet (FUV) imager is a CzernyTurner design Spectrographic Imager with two exit slits and corresponding back imager cameras that produce two independent images in separate wavelength bands on two detectors. All observations will be processed as limb altitude profiles. In addition, the ionospheric 135.6 nm data will be processed as longitude and latitude spatial maps to obtain images of ion distributions around regions of equatorial spread F. The ICON FUV optic axis is pointed 20 degrees below local horizontal and has a steering mirror that allows the field of view to be steered up to 30 degrees forward and aft, to keep the local magnetic meridian in the field of view. The detectors are micro channel plate (MCP) intensified FUV tubes with the phosphor fiber-optically coupled to Charge Coupled Devices (CCDs). The dual stack MCP-s amplify the photoelectron signals to dominate the CCD noise and the rapidly scanned frames are co-added to digitally create 12-second integrated images. Digital on-board signal processing is used to compensate for geometric distortion and satellite motion and to achieve data compression. The instrument was originally aligned in visible light by using a special grating and visible cameras. Final alignment, functional and environmental testing and calibration were performed in a large vacuum chamber with a UV source. The test and calibration program showed that ICON FUV meets its design requirements and is ready to be launched on the ICON spacecraft.

Optical trapping for biosensing: materials and applications.

Since the 70's, when Arthur Ashkin and coworkers demonstrated that optical forces could displace and levitate microsized particles, optical trapping has seen a steady stream of developments and applications, particularly in the biological field. Since that demonstration, optical trapping has been especially exploited as a powerful tool for non-invasive sensitive measurements. The recent development of synthesis routes has further expanded the possibilities of optical trapping in the area of biosensing where new multifunctional particles are used as a single probe. The synergy between the development of new materials and experimental techniques has led to the appearance of numerous studies in which novel biosensing applications are demonstrated. The design of new materials and optical systems to face new challenges makes it necessary to have a clear idea about the latest developments achieved in the field. In this work, we summarize recent experimental advances in biosensing achieved by optical manipulation of micro- and nanoparticles providing a critical review on the state of the art and future prospects.

Assessing Single Upconverting Nanoparticle Luminescence by Optical Tweezers.

We report on stable, long-term immobilization and localization of a single colloidal Er(3+)/Yb(3+) codoped upconverting fluorescent nanoparticle (UCNP) by optical trapping with a single infrared laser beam. Contrary to expectations, the single UCNP emission differs from that generated by an assembly of UCNPs. The experimental data reveal that the differences can be explained in terms of modulations caused by radiation-trapping, a phenomenon not considered before but that this work reveals to be of great relevance.

Gold nanorod assisted intracellular optical manipulation of silica microspheres.

We report on the improvement of the infrared optical trapping efficiency of dielectric microspheres by the controlled adhesion of gold nanorods to their surface. When trapping wavelength was equal to the surface plasmon resonance wavelength of the gold nanorods (808 nm), a 7 times improvement in the optical force acting on the microspheres was obtained. Such a gold nanorod assisted enhancement of the optical trapping efficiency enabled the intracellular manipulation of the decorated dielectric microsphere by using a low power (22 mW) infrared optical trap.

Tiroides ectópico asociado con Graves-Basedow / Ectopic thyroids associated with Graves-Basedow Disease

Se presenta un caso de tiroides ectópico sublingual asociado a enfermedad de Graves-Basedow en un niño de 16 años con antecedentes personales de diabetes mellitus tipo 1 desde los 11 años. La verdadera incidencia de tiroides ectópico es desconocida por cursar la mayor parte de ellos de forma asintomática; en caso de presentar clínica, suele ser hipotiroidismo, siendo excepcional su asociación a hipertiroidismo (AU)

A case is presented of sublingual ectopic thyroid associated to Graves-Basedow disease in a 16 year-old male child with personal background of Diabetes Mellitus 1 from 11 years of age. The true incidence of ectopic thyroid is unknown as it mostly occurs symptomatically. If there are symptoms, they are generally hypothyroidism, its association to hyperthyroidism being very rare (AU)

Evaluation of ion release, cytotoxicity, and platelet adhesion of electrochemical anodized 316 L stainless steel cardiovascular stents.

316L Stainless steel is one of the most used metallic material in orthopedical prosthesis, osteosinthesis plates, and cardiovascular stents. One of the main problems this material presents is the nickel and chromium release, specially the Ni ion release that provokes allergy in a high number of patients. Recently, experimental applications in vitro and in vivo seem to indicate that the thickness of the nature oxide of the stainless steel results in very strong reinforcement of the biological response and reduce the ion release due to the thicker surface oxide. It is possible to grow the natural chromium oxide layer by electrolytic method such anodization. In this study, two main anodization methods to grow chromium oxide on the 316L stainless steel have been evaluated. Nickel and Chromium ions release in human blood at 37 degrees C were detected at times of 1, 6, 11, and 15 days by means of atomic absorption in a graphite furnace (GAAF). Moreover, cytocompatibility tests were carried out. Perfusion experiments were performed to evaluate morphometrically platelet interaction with the material and to explore the potential thrombogenicity. The results showed a good cytocompatibility between the material and the osteoblast-like cells. However, these anodization methods released between 2 and 10 times more nickel and chromium than the original stainless steel, depending on the method used. Besides, anodized samples shown an increase of the percentage of surface covered by platelets. Consequently, the anodization methods studied do not improve the long-term behavior of the stainless steel for its application as cardiovascular stents.

Dental casting alloys behaviour during power toothbrushing with toothpastes of various abrasivities. Part II: corrosion and ion release.

The purpose of this study was to evaluate the long term effect of abrasivity of toothpastes normally used over the corrosion behavior and ion release of the different dental casting alloys. Three dental casting alloys (Ni-Cr, Co-Cr and commercially pure Ti) were studied. Four specimens of each material were immersed, brushed without paste or brushed with one of four toothpastes of different Relative Dentine Abrasivity (RDA 50, 52, 80, and 114). An electric toothbrush with a load of 250 g was used for 420 min. Corrosion behavior was determined by means a potenciostat with high sensitivity and the ion release determined by Inductively Coupled Plasma-Mass Spectrometry. Two-way ANOVA and non-parametric tests were used to detect significant differences. Titanium specimens exhibited the best corrosion behavior after and before the toothbrushed, being the worst of the three alloys the Cr-Ni. Titanium oxide produced spontaneously on the Ti surface is the main cause of the high corrosion resistance of the material. However, the eutectoid of the CrNi with chemical composition between different phases produces pitting on the phases boundaries with an important decrease of the corrosion resistance. Besides, the CrNi produces high values of the Ni and Cr release. Slight increment in roughness were observed after toothbrushing and depended on the material but not on the toothpaste used. The increase of the microhardness (residual stresses) provokes a decrease of the corrosion resistance and an increase of the ion release.

Dental casting alloys behaviour during power toothbrushing with toothpastes with various abrasivities. Part I: wear behavior.

The purpose of this study was to evaluate the long term effect of abrasivity of toothpastes normally used over the surface and mechanical properties of dental casting alloys. Three dental casting alloys (Ni-Cr, Co-Cr, c.p. Ti) and one ceramic were chosen. Four specimens of each material were immersed in artificial saliva, brushed without or with one of four toothpastes of different Relative Dentine Abrasivity (RDA 50, 52, 80, and 114). An electric toothbrush with a load of 250 g was used for 420 min. Mass loss was determined by difference in weight, microhardness and surface roughness were also measured. Two-way ANOVA and non-parametric tests were used to detect significant differences. Titanium specimens (478 microg/cm(2)) exhibited the most mass loss, whereas ceramic (282 microg/cm(2)) and Co-Cr (262 microg/cm(2)) exhibited the least. However, ceramic demonstrated the most volume loss (0.239 mm(3)). The abrasivity effect of the toothpaste correlated with the RDA values. Slight variations in microhardness were observed after toothbrushing and depended on the material but not on the toothpaste used. Material surfaces were slightly smoothed by toothbrushing but no significant differences were detected. Dental casting alloys and ceramic are susceptible to abrasion by brushing with an electric toothbrush depending on the RDA value of the toothpaste. Variations in microhardness and surface roughness were not clinically relevant.

Esporotricosis transmitida por gatodoméstico. Reporte de un caso / Sporotrichosis transmitted by a domestic cat. Case report

La esporotricosis es la micosis subcutánea más frecuente en México, cuyo agente causal es Sporothrix schenckii y se considera en algunos casos como una zoonosis. Se presente el caso de una paciente femenina de 43 años, con nódulos ulcerados en el antebrazo después de haber sido arañada por su gato, quien igualmente tenía lesiones en su cuerpo. La paciente se diagnosticó clínica y micológicamente como una esporotricosis linfangítica. Recibió itraconazol 200 mg/día por 3 meses con resolución de las lesiones (AU)

Sporotrichosis is the most common subcutaneous mycosis in Mexico which is caused by Sporothrix schenckii and in some cases it has been consideredas a zoonosis. A 43-year-old women who developed ulcerated nodules in her forearm after a scratch of her cat which also has lesions in his body, isreported. The patient had a clinic and mycological diagnosis of lymphocutaneous sporothrichosis. Itraconazol 200 mg/daily during 3 months was given with complete remission (AU)

Laser welding of NiTi orthodontic archwires for selective force application.

Conventional superelastic orthodontic wires are arch-shaped, have the same mechanical properties all along their length and are used to correct the position of teeth. The disadvantage of these archwires is that there are different types of teeth in the mouth and different forces are therefore needed to rectify their position. The aim of this work was to laser weld several types of NiTi orthodontic wires that had different chemical compositions and superelastic properties, in order to adjust their properties to different parts of the mouth. Microstructural changes, transformation stresses and temperatures, variations in corrosion behaviour and ion release were studied in the welded wires.

Surface-enhanced Raman scattering study of the interaction of red dye alizarin with ovalbumin.

Surface-enhanced Raman spectroscopy and UV-vis absorption spectroscopy were employed to study the interaction between the red dye alizarin and ovalbumin (OA), to check the effect of binding media usually employed when applying this pigment in painting practices based on egg tempera. The protein/alizarin interaction is rather weak and takes place through the alizarin neutral form, which interacts with exposed hydrophobic moieties of OA. This effect is of great interest from an artistic point of view because the dye color can be modified. Furthermore, the interaction with alizarin could induce a change in the protein structure, leading to a denaturation and subsequent aggregation.

Folding kinetics of phage 434 Cro protein.

Folding kinetics for phage 434 Cro protein are examined and compared with those reported for lambda(6-85), the N-terminal domain of the repressor of phage lambda. The two proteins have similar all-helical structures consisting of five helices but different stabilities. In contrast to lambda(6-85), sharp and distinct aromatic (1)H NMR signals without exchange broadening characterize the native and urea-denatured 434 Cro forms at equilibrium at 20 degrees C, indicating slow interconversion on the NMR time scale. Stopped-flow fluorescence data using the single 434 Cro tryptophan indicate strongly urea-dependent refolding rates and smaller urea dependencies of the unfolding rates, suggesting a native-like transition state ensemble. Refolding rates are slower and unfolding rates considerably faster at pH 4 than at pH 6. This accounts for the lower stability of 434 Cro at pH 4 and suggests the existence of pH-dependent, possibly salt bridge interactions that are more stabilizing at pH 6. At <2 M urea, decreased folding amplitudes and nonlinear urea dependencies that are apparent at pH 6 indicate deviation from two-state behavior and suggest the formation of an early folding intermediate. The folding behavior of 434 Cro and why it folds 2 orders of magnitude slower than lambda(6-85) are rationalized in terms of the lower intrinsic helix stabilities and putative charge interactions in 434 Cro.

Hydrogen exchange in ribonuclease A and ribonuclease S: evidence for residual structure in the unfolded state under native conditions.

Two-dimensional NMR spectroscopy has been used to monitor the exchange of backbone amide protons in ribonuclease A (RNase A) and its subtilisin-cleaved form, ribonuclease S (RNase S). Exchange measurements at two different pH values (5.4 and 6.0) show that the exchange process occurs according to the conditions of the EX2 limit. Differential scanning calorimetry measurements have been carried out in 2H2O under conditions analogous to those used in the NMR experiments in order to determine the values of DeltaCp, DeltaHu and Tm, corresponding to the thermal denaturation of both proteins. For the amide protons of a large number of residues in RNase A, the free energies at 25 degreesC for exchange competent unfolding processes are much lower than the calorimetric denaturation free energies, thus showing that exchange occurs through local fluctuations in the native state. For 20 other protons, the cleavage reaction had approximately the same effect on the exchange rate constants than on the equilibrium constant for unfolding, indicating that those protons exchange by global unfolding. There is a good agreement between the residues to which these protons belong and those involved in the putative folding nucleation site identified by quench-flow NMR studies. The unfolding free energies of the slowest exchanging protons, DeltaGex, as evaluated from exchange data, are much larger than the calorimetric free energies of unfolding, DeltaGu. Given the agreement between DeltaDeltaGex(A-S), the difference in free energy from exchange for a given proton of the two proteins, and DeltaDeltaGu(A-S), the difference in the calorimetric free energy of the two proteins, the discrepancy indicates that the intrinsic exchange rates in the unfolded state of those protons cannot be approximated by those measured in short unstructured peptides and, consequently, exchange for those protons in RNase A and S must occur through a rather structured denatured state.

Solution structure determination by two-dimensional 1H NMR of omega-conotoxin MVIID, a calcium channel blocker peptide.

The three-dimensional structure of omega-conotoxin MVIID has been determined in aqueous solution by two-dimensional 1H NMR techniques. A total of 267 relevant upper-bound distance restraints were used to obtain a family of convergent structures using molecular dynamics methods. A standard simulated annealing protocol using the XPLOR program included in ARIA provided a total of 18 final structures. The averaged RMSD between these structures and the mean atomic coordinates was 0.8 +/- 0.3 A for the backbone atoms. The highest mobility was observed in the segments between residues 10 to 13, comprising Tyr 13, one of the residues shown to be important for binding of omega-conotoxin GVIA and MVIIA to N-type calcium channels. The three-dimensional structure is stabilised by the three disulfide bonds and includes a short antiparallel beta-strand between residues 5-8, 23-25 and 19-21. The folding for this non-N-type calcium channel blocker is similar to that previously calculated for omega-conotoxins GVIA, MVIIA and MVIIC. This suggests the disulfide bond pattern fixes the structure. The reported three-dimensional information can be used to advantage in order to highlight the structural parameters involved in discrimination among calcium channel subtypes.