Enhanced sensitivity in non-enzymatic glucose detection by improved growth kinetics of Ni-based nanostructures.

Ni-based nanostructures are attractive catalytic materials for many electrochemical applications, among which are non-enzymatic sensing, charge storage, and water splitting. In this work, we clarify the synthesis kinetics of Ni(OH)2/NiOOH nanowalls grown by chemical bath deposition at room temperature and at 50 °C. We applied the results to non-enzymatic glucose sensing, reaching a highest sensitivity of 31 mA cm-2mM-1. Using scanning electron microscopy, x-ray diffraction analysis and Rutherford backscattering spectrometry we found that the growth occurs through two regimes: first, a quick random growth leading to disordered sheets of Ni oxy-hydroxide, followed by a slower growth of well-aligned sheets of Ni hydroxide. A high growth temperature (50 °C), leading mainly to well-aligned sheets, offers superior electrochemical properties in terms of charge storage, charge carrier transport and catalytic action, as confirmed by cyclic voltammetry and electrochemical impedance spectroscopy analyses. The reported results on the optimization and application of low-cost synthesis of these Ni-based nanostructures have a large potential for application in catalysis, (bio)sensing, and supercapacitors areas.

Hydrogen induced optically-active defects in silicon photonic nanocavities.

We demonstrate intense room temperature photoluminescence (PL) from optically active hydrogen- related defects incorporated into crystalline silicon. Hydrogen was incorporated into the device layer of a silicon on insulator (SOI) wafer by two methods: hydrogen plasma treatment and ion implantation. The room temperature PL spectra show two broad PL bands centered at 1300 and 1500 nm wavelengths: the first one relates to implanted defects while the other band mainly relates to the plasma treatment. Structural characterization reveals the presence of nanometric platelets and bubbles and we attribute different features of the emission spectrum to the presence of these different kind of defects. The emission is further enhanced by introducing defects into photonic crystal (PhC) nanocavities. Transmission electron microscopy analyses revealed that the isotropicity of plasma treatment causes the formation of a higher defects density around the whole cavity compared to the ion implantation technique, while ion implantation creates a lower density of defects embedded in the Si layer, resulting in a higher PL enhancement. These results further increase the understanding of the nature of optically active hydrogen defects and their relation with the observed photoluminescence, which will ultimately lead to the development of intense and tunable crystalline silicon light sources at room temperature.

Enhanced 1.54 µm emission in Y-Er disilicate thin films on silicon photonic crystal cavities.

We introduce an Y-Er disilicate thin film deposited on top of a silicon photonic crystal cavity as a gain medium for active silicon photonic devices. Using photoluminescence analysis, we demonstrate that Er luminescence at 1.54 µm is enhanced by coupling with the cavity modes, and that the directionality of the Er optical emission can be controlled through far-field optimization of the cavity. We determine the maximum excitation power that can be coupled into the cavity to be 12 mW, which is limited by free carrier absorption and thermal heating. At maximum excitation, we observe that nearly 30% of the Er population is in the excited state, as estimated from the direct measurement of the emitted power. Finally, using time-resolved photoluminescence measurements, we determine a value of 2.3 for the Purcell factor of the system at room temperature. These results indicate that overcoating a silicon photonic nanostructure with an Er-rich dielectric layer is a promising method for achieving light emission at 1.54 µm wavelength on a silicon platform.

Quantum confinement and electroluminescence in ultrathin silicon nanowires fabricated by a maskless etching technique.

We present a novel approach for the direct synthesis of ultrathin Si nanowires (NWs) exhibiting room temperature light emission. The synthesis is based on a wet etching process assisted by a metal thin film. The thickness-dependent morphology of the metal layer produces uncovered nanometer-size regions which act as precursor sites for NW formation. The process is cheap, fast, maskless and compatible with Si technology. Very dense arrays of long (several micrometers) and small (diameter of 5-9 nm) NWs have been synthesized. An efficient room temperature luminescence, visible with the naked eye, is observed when NWs are optically excited, exhibiting a blue-shift with decreasing NW size in agreement with quantum confinement effects. A prototype device based on Si NWs has been fabricated showing a strong and stable electroluminescence at low voltages. The relevance and the perspectives of the reported results are discussed, opening the route toward novel applications of Si NWs.

Breast MR with special focus on DW-MRI and DCE-MRI.

The use of magnetic resonance imaging (MRI) for the assessment of breast lesions was first described in the 1970s; however, its wide application in clinical routine is relatively recent. The basic principles for diagnosis of a breast lesion rely on the evaluation of signal intensity in T2-weighted sequences, on morphologic assessment and on the evaluation of contrast enhancement behaviour. The quantification of dynamic contrast behaviour by dynamic contrast-enhanced (DCE) MRI and evaluation of the diffusivity of water molecules by means of diffusion-weighted MRI (DW-MRI) have shown promise in the work-up of breast lesions. Therefore, breast MRI has gained a role for all indications that could benefit from its high sensitivity, such as detection of multifocal lesions, detection of contralateral carcinoma and in patients with familial disposition. Breast MRI has been shown to have a role in monitoring of neoadjuvant chemotherapy, for the evaluation of therapeutic results during the course of therapy. Breast MRI can improve the determination of the remaining tumour size at the end of therapy in patients with a minor response. DCE-MRI and DW-MRI have shown potential for improving the early assessment of tumour response to therapy and the assessment of residual tumour after the end of therapy. Breast MRI is important in the postoperative work-up of breast cancers. High sensitivity and specificity have been reported for the diagnosis of recurrence; however, pitfalls such as liponecrosis and changes after radiation therapy have to be carefully considered.

[Validation of an hourly transcutaneous bilirubin nomogram in a population of term or late preterm newborn infants: preliminary results]. / Validazione di un nomogramma orari di bilirubina transcutanea in una popolazione di neonati a termine o late preterm: risultati preliminari.

OBJECTIVE: The aim of this study was to asses the validity of the TCB nomogram for the European population for predicting significant hyperbilirubinemia in healthy term and late-preterm newborns. METHODS: This observational study was conducted from February 2009 to December 2009 in the well-baby nurseries of Gemelli hospital of Rome. The predictive ability of the skin bilirubin (TCB) nomogram was prospectively assessed in 926 neonates with gestational age ?35 weeks. TCB was measured with Bilichek and total serum bilirubin (TSB) was contemporary assayed by the standard spectrophotometric method. Every neonate was assess for a single TCB and TSB value. RESULTS: The mean TSB values was 8.2 +/- 3.2 mg/dl, while the mean TCB values was 9.5 +/- 3.6 mg/dl A sensitivity of 100% and a negative predictive value of 100% were obtained with a single bilirubin determination applying the 75 degrees percentile of our nomogram. CONCLUSION: The 75 degrees percentile of the skin bilirubin nomogram for the European population in the first 96 hours of life is able to predict all neonates at risk of severe hyperbilirubinemia. It could facilitate a safe discharge from the hospital and a targeted intervention and follow-up reducing the need for blood samples.

Control of growth mechanisms and orientation in epitaxial Si nanowires grown by electron beam evaporation.

The growth mechanisms of epitaxial Si nanowires (NWs) grown by electron beam evaporation (EBE) and catalyzed through gold droplets are identified. NWs are seen to grow both from adsorbed Si atoms diffusing from the substrate and forming a dip around them, and from directly impinging atoms. The growth of a 2D planar layer competing with the axial growth of the NWs is also observed and the experimental parameters determining which of the two processes prevails are identified. NWs with (111), (100) and (110) orientation have been found and the growth rate is observed to have a strong orientation dependence, suggesting a microscopic growth mechanism based on the atomic ordering along (110) ledges onto (111)-oriented terraces. By properly changing the range of experimental conditions we demonstrate how it is possible to favor the axial growth of the NWs, define their length and control their crystallographic orientation.

Dactylitis, a term for different digit diseases.

Dorland's Illustrated Medical Dictionary gives the following definition of dactylitis (deltaalphachitauupsilonlambdaomicronsigma = digit): 'inflammation of a finger or toe'. Although any inflammatory process involving the fingers or toes may be called dactylitis, the term has entered in current use only in some well-defined entities. These differ in the involved tissue of the digit and in the type of involvement. Tuberculous dactylitis is the variant of tuberculous osteomyelitis affecting the short tubular bone of the hands and feet. Radiographs typically show a central, lytic, cystic, and expansive lesion known as spina ventosa. Syphilitic dactylitis is a manifestation of congenital syphilis. Radiological findings mimic those of tuberculous dactylitis but the involvement is bilateral and symmetric. Sarcoid dactylitis is due to typical non-caseating granulomas invading the phalanges and the adjacent soft tissue. Blistering distal dactylitis is an infection of the anterior fat pad on the volar surface of the distal portion of a single finger or more rarely a toe, mostly caused by group A beta-haemolytic streptococci. Sickle cell dactylitis, also known as 'hand-foot syndrome', is due to localized bone marrow infarction of the carpal and tarsal bones and phalanges. Spondyloarthritis dactylitis, also called 'sausage-like' digit, is a diffuse painful swelling of the fingers and toes. Recent ultrasonography (US) and magnetic resonance imaging (MRI) studies on both finger and toe dactylitis have established that dactylitis is due to flexor tenosynovitis and that the enlargement of the joint capsule is not an indispensable condition for the 'sausage-like' feature. There is no evidence of enthesitis of flexor digitorum tendons and joint capsule.

Room temperature migration of boron in crystalline silicon.

We demonstrate that substitutional B in silicon can migrate even at room temperature and below, stimulated by a high interstitial flux. Once mobile B is formed, it migrates for long distances with a diffusivity >5 x 10(-13) cm(2)/s, until it assumes an immobile configuration with a migration length independent of the temperature. This phenomenon is present during secondary ion mass spectrometry (SIMS) analyses of B profiles, altering the profile during the analysis itself. These results shed new light on all the data based on SIMS analyses and reported in literature in the last decades.

Capillaroscopic findings in erosive and nodal osteoarthritis of the hands.

Osteoarthritis of the hands is a very common disease that can present a large number of different clinic pictures, such as nodal (NOA) and erosive (EOA) forms. EOA in particular is a rare subset of hand osteoarthritis characterised by faster destructive changes involving the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints. In the early stages of the disease the differential diagnosis from other arthritides, such as rheumatoid or seronegative arthritis, may pose a challenge. Nailfold capillaroscopy is a non-invasive technique that allows the in vivo study of the microvascular environment. In this study the authors have compared the capillaroscopic microvascular patterns in 56 patients with EOA, in 46 patients with NOA, and in 50 normal controls. The abnormalities that could be found in EOA patients were similar to those described by some authors in patients with psoriatic arthritis. The authors discuss the significance of these abnormalities and the possible relationship between EOA and psoriatic arthritis.

Structural and optical properties of silicon nanocrystals grown by plasma-enhanced chemical vapor deposition.

Silicon nanocrystals (Si-nc) embedded in SiO2 matrix have been prepared by high temperature thermal annealing (1000-1250 degrees C) of substoichiometric SiOx films deposited by plasma-enhanced chemical vapor deposition (PECVD). Different techniques have been used to examine the optical and structural properties of Si-nc. Transmission electron microscopy analysis shows the formation of nanocrystals whose sizes are dependent on annealing conditions and deposition parameters. The spectral positions of room temperature photoluminescence are systematically blue shifted with reduction in the size of Si-nc obtained by decreasing the annealing temperature or the Si content during the PECVD deposition. A similar trend has been found in optical absorption measurements. X-ray absorption fine structure measurements indicate the presence of an intermediate region between the Si-nc and the SiO2 matrix that participates in the light emission process. Theoretical observations reported here support these findings. All these efforts allow us to study the link between dimensionality, optical properties, and the local environment of Si-nc and the surrounding SiO2 matrix.

Optical gain in silicon nanocrystals.

Adding optical functionality to a silicon microelectronic chip is one of the most challenging problems of materials research. Silicon is an indirect-bandgap semiconductor and so is an inefficient emitter of light. For this reason, integration of optically functional elements with silicon microelectronic circuitry has largely been achieved through the use of direct-bandgap compound semiconductors. For optoelectronic applications, the key device is the light source--a laser. Compound semiconductor lasers exploit low-dimensional electronic systems, such as quantum wells and quantum dots, as the active optical amplifying medium. Here we demonstrate that light amplification is possible using silicon itself, in the form of quantum dots dispersed in a silicon dioxide matrix. Net optical gain is seen in both waveguide and transmission configurations, with the material gain being of the same order as that of direct-bandgap quantum dots. We explain the observations using a model based on population inversion of radiative states associated with the Si/SiO2 interface. These findings open a route to the fabrication of a silicon laser.

Role of color Doppler sonography in the assessment of musculoskeletal soft tissue masses.

Fifty-six patients with soft tissue masses of the limbs (36 benign, 20 malignant) prospectively underwent sonography (color Doppler and pulsed Doppler examinations) to assess the role of Doppler interrogation in differentiating benign from malignant lesions. Sonography showed 60% sensitivity, 55% specificity, 71% negative predictive value, 42% positive predictive value, and 57% accuracy. Color Doppler evaluation showed 85% sensitivity, 88% specificity, 91% negative predictive value, 80% positive predictive value, and 87% accuracy. Diastolic and venous velocities and pulsatility index values were not statistically significant. Mean systolic velocity was 0.27 m/s in benign lesions and 0.55 m/s in malignant lesions. By combining sonographic and Doppler data, a correct diagnosis was obtained in 51 of 56 patients (90% sensitivity, 91% specificity, 85% positive predictive value, 94% negative predictive value, 91% accuracy). Color Doppler and pulsed Doppler evaluations represent a useful adjunct to sonography and should be routinely included in the evaluation of musculoskeletal soft tissue masses by ultrasonography.

Primary bone tumors and pseudotumors of the lumbosacral spine.

Primary tumors of the spine are relatively infrequent lesions compared with metastatic disease, multiple myeloma, and lymphoma which are the more frequent neoplasms of the spine and usually manifest with multifocal lesions and thus pose little diagnostic dilemma. However, in the presence of a solitary spinal lesion, the more uncommon primary tumors of the spine represent an important group of entities for diagnostic consideration. The most common benign and malignant primary tumors of the spine are enostosis, osteoid osteoma, osteoblastoma, giant cell tumor, aneurysmal bone cyst, osteochondroma, chordoma, chondrosarcoma, Ewing sarcoma, primitive neuroectodermal tumor, and osteosarcoma. The imaging features of these lesions are often characteristic. Radiologists should be aware of the appearance of these unusual tumors in order to provide a complete differential diagnosis.

Craniocervical junction involvement in rheumatoid arthritis: a clinical and radiological study.

OBJECTIVE: To make a comparative evaluation of different imaging techniques for studying the craniocervical junction involvement in patients with rheumatoid arthritis (RA). Upper cervical spine involvement was compared with clinical and immunological data. METHODS: Patients (n = 47) underwent plain radiographs and computerized tomography (CT) and magnetic resonance (MR) study of the craniocervical junction. Neurological examination following clinical signs of possible atlantoaxial involvement was performed in all patients following the Ranawat classification. RESULTS: Radiographic and MR images showed craniocervical involvement in 41.3% and 61% of the patients, respectively. Immunological data were not correlated with imaging findings, whereas Ranawat class II and III of neurological involvement seem to be predictive of atlantoaxial alteration. CONCLUSION: Conventional radiography allowed us to detect 41.3% of patients with craniocervical involvement, but only in advanced stages of the disease. MR imaging had the unique potential of direct and detailed synovial visualization, especially in the gadolinium enhanced axial images, resulting in the early diagnosis of craniocervical RA.

The current role of radiography in the assessment of skeletal tumors and tumor-like lesions.

Radiography offers more information than any other imaging modality in the study of bone lesions and remains the cornerstone for the differential diagnosis of skeletal tumors and tumor-like lesions thanks to its higher specificity in detecting tumor morphologic hallmarks. the radiographic features that help the radiologist make the diagnosis of a bone tumor or tumor-like lesion, or at least narrow the diagnostic possibilities, include patterns of bone destruction (geographic, moth-eaten and permeated), lesion margins (from sclerotic rim to ill-defined margin), internal characteristics of the lesion (non-matrix producing tumors, non-mineralized matrix producing tumors, mineralized matrix producing tumors), type of host bone response (medullary or periosteal), location (femur, tibia, humerus, etc.), site (metaphysis, diaphysis or epiphysis), and position (central, eccentric or periosteal) of the lesion in the skeletal system and in the individual bone, soft tissue involvement, and single or multiple lesion nature. Patterns of bone destruction, margins, and reactive changes in the host bone clearly depict the growth rate of a bone lesion, that is its biologic activity; the matrix of the lesion, as well as lesion location, site and position may allow a specific diagnosis. This general information coupled with clinical information helps define whether the lesion is neoplastic or non-neoplastic, benign or malignant, primary or metastatic, and will help further direct the subsequent work-up. CT may be indicated for the optimal assessment of tumor matrix especially in complex anatomical sites, such as the spine, pelvis and hindfoot. The main role of MRI lies in local tumor staging, especially for planning limb-salving resections. Biopsy is the definitive diagnostic procedure and should be carried out only after the appropriate diagnostic and staging tests. Whenever a bone lesion is suspected, clinical-radiologic pathologic correlation is essential to make a more accurate diagnosis and to improve patient care.

Skeletal benign bone-forming lesions.

The imaging features of benign osseous lesions of the bone are often characteristic and suggestive of a specific diagnosis. This is particularly true for skeletal benign bone-forming lesions such as enostosis, osteoma, osteoid osteoma and osteoblastoma. Enostosis or bone island is an incidental finding in the axial skeleton (pelvis, spine, ribs) of asymptomatic patients; it appears as a small (0.2-2 cm) round to oval sclerotic area with irregular, radiating ('thorny') spicules peripherally. Osteoma is a benign slow-growth tumor and usually an incidental finding in cranial sinuses, vault and mandible, and presenting as a homogeneous, sharply defined bone mass arising from bone surface; its signs and symptoms are rare and depend on the tumor size and location--e.g. sinusitis, headache, exophthalmos, diplopia. Osteoid osteoma is a painful highly vascularized benign tumor usually affecting the long bone diaphysis cortex of young patients; it generally appears as a small radiolucent nidus with or without central calcification and surrounding bone sclerosis on radiographs, and as a 'hot' spot on scintigraphy. CT is the method of choice for the definite location of the nidus especially in sites of complex anatomy, such as the spine, pelvis and hindfoot. Osteoblastoma is a rare tumor, histologically similar to osteoid osteoma but with a significantly different clinical potential because of the possibilities of postoperative recurrence, of its locally aggressive behavior or, rarer still, malignant transformation; the spine and long bones are affected in more than half the cases. Its radiologic appearance is not always distinctive and usually characterized by a lytic lesion with varying bone production and expansile behavior; CT and MRI are required for the diagnosis of spinal osteoblastomas. When a bone-producing tumor or tumor-like lesion is suspected but no specific diagnosis can be made, the knowledge of the range of the imaging findings of these lesions will allow a suitably ordered differential diagnosis. Radiography is the single most effective imaging method in this respect. CT is required for the tumors in complex anatomical sites, such as the spine, pelvis and hindfoot, as well as for the optimal assessment of the tumor matrix. MRI is specifically required to study the lesion effect on the spinal canal.

Clinical trials in rheumatoid arthritis: methodological suggestions for assessing radiographs arising from the GRISAR Study. Gruppo Reumatologi Italiani Studio Artrite Reumatoide.

OBJECTIVES: The three x ray assessors of the GRISAR study (blinded to treatment) gave consensual erosion and damage scores to the baseline and 12 month radiographs of 284 rheumatoid arthritis (RA) patients using three different methods: single readings (blinded as to patient and chronological sequence of the x rays), paired readings (blinded as to sequence), and chronologically ordered paired readings. The aim was to evaluate which of these reading procedures is the most appropriate for clinical trials. METHODS: The progression of the scores obtained using each procedure was compared by means of descriptive statistics, principal components analysis, and intra-patient correlation coefficients of pairs of methods. Bootstrap estimates of the variance of the difference in the means of two equally sized random samples were calculated to evaluate the power of the statistical analysis performed to assess the possible treatment effect for both paired and chronological reading methods. RESULTS: (a) The standard deviations of the paired and chronological readings were similar, but that of the single readings was higher. (b) The knowledge that two x rays were of the same patient accounted for a sizeable proportion of the between method variability. (c) Agreement was satisfactory between the paired and chronological methods for both scores but, between them and the single readings, it was modest for erosions and poor for damage. (d) The bootstrap estimate of the variance of the difference was smaller for the paired than the chronological method, possibly giving it greater power to test treatment effect. CONCLUSIONS: These results suggested that paired readings were the most suitable for evaluating the progression of joint damage in the GRISAR study.

Lumbosacral junction injury associated with unstable pelvic fracture: classification and diagnosis.

PURPOSE: To determine the types and prevalence of lumbosacral junction injuries associated with an unstable pelvic fracture and to assess the diagnostic value of conventional radiographic and computed tomographic (CT) findings. MATERIALS AND METHODS: Anteroposterior, inlet, and outlet radiographs and CT scans in 97 patients with pelvic disruption were retrospectively reviewed. RESULTS: Unstable pelvic fractures were seen on radiographs in 73 patients, 42 of whom had a sacral fracture. Fourteen of these 42 patients had an associated L5-S1 facet joint injury (three extraarticular, nine articular, and two complex). In three of these 14 patients, the L-5 body was laterally bent by more than 10 degrees, with asymmetric L5-S1 intervertebral space. The diagnosis in nine of the 14 patients with an associated lumbosacral junction injury was rendered on the basis of CT findings only. CONCLUSION: Lumbosacral junction injury must be considered in patients with an unstable pelvic fracture, especially in those with an associated sacral fracture. CT is necessary because these conditions may be overlooked on radiographs, although outlet radiographs are better than CT scans for depicting the possibly associated L5-S1 intervertebral disk lesion.

The radiological assessment of rheumatoid arthritis.

Antirheumatic therapy has changed from a rather conservative approach towards more aggressive early intervention. Objective measures of the course and outcome of rheumatoid arthritis are essential to understand the disease process and evaluate the therapeutic response. Radiological evaluation fulfils many of the criteria of objectivity: the films provide a permanent record and can be evaluated serially and repeatedly; the changes do not fluctuate with disease activity; and good technique and correct timing can keep the radiation load to a very acceptable level. Consequently, therapies can be evaluated on the basis of their efficacy on radiological progression. In clinical practice, a visual qualitative assessment is usually sufficient, but for therapeutic trials or studies of disease progression in certain patient groups, quantitative methods are needed. A number of different evaluation systems have been introduced, but none of these have gained universal acceptance. No ideal evaluation method (which should be rapid, easy to use and have a good level of reproducibility) has yet been found. Here we make provisional recommendations on the conduct of future therapeutic trials to maximise the likelihood that they will give conclusive results using radiographic outcome assessments.