Controlled Assembly of CdSe Nanoplatelet Thin Films and Nanowires

We assemble semiconductor CdSe nanoplatelets (NPs) at the air/liquid interface into 2D monolayers several micrometers wide, distinctly displaying nematic order. We show that this configuration is the most favorable energetically and that the edge-to-edge distance between neighboring NPs can be tuned by ligand exchange without disrupting film topology and nanoparticle orientation. We explore the rich assembly phase space by using depletion interactions to direct the formation of 1D nanowires from stacks of NPs. The improved control and understanding of the assembly of semiconductor NPs offers opportunities for the development of cheaper optoelectronic devices that rely on 1D or 2D charge delocalization throughout the assembled monolayers and nanowires.

Assessment of environmental parameters effect on potentially toxic elements mobility in foreshore sediments to support marine-coastal contamination prediction

Potentially toxic elements (PTEs) presence in marine sediments can significantly affect the environmental quality and negatively influence economy and recreational activities in related areas. Accordingly, contamination monitoring and control in the marine environment is a fundamental task. In this work, four PTEs behavior (i.e. As, Hg, Pb, and Zn) in sandy foreshore sediments (SFSs) was thoroughly investigated at different pH, redox potential and temperature conditions of the marine water. For all the tests, the released As was 2.7-6 times higher than its initial concentration in water. Nonetheless, final mass balances showed that preferential release in the liquid phase occurred for Pb and Hg (up to 10 % and 9.1 %, respectively). Moreover, final Zn and Hg content increase in SFSs labile fractions indicated their higher bioavailability after the tests. The obtained results outline an approach useful to predict the contaminants behavior in marine matrices and support environmental monitoring and preservation strategies.

Design Rules for Obtaining Narrow Luminescence from Semiconductors Made in Solution

Solution-processed semiconductors are in demand for present and next-generation optoelectronic technologies ranging from displays to quantum light sources because of their scalability and ease of integration into devices with diverse form factors. One of the central requirements for semiconductors used in these applications is a narrow photoluminescence (PL) line width. Narrow emission line widths are needed to ensure both color and single-photon purity, raising the question of what design rules are needed to obtain narrow emission from semiconductors made in solution. In this review, we first examine the requirements for colloidal emitters for a variety of applications including light-emitting diodes, photodetectors, lasers, and quantum information science. Next, we will delve into the sources of spectral broadening, including "homogeneous" broadening from dynamical broadening mechanisms in single-particle spectra, heterogeneous broadening from static structural differences in ensemble spectra, and spectral diffusion. Then, we compare the current state of the art in terms of emission line width for a variety of colloidal materials including II-VI quantum dots (QDs) and nanoplatelets, III-V QDs, alloyed QDs, metal-halide perovskites including nanocrystals and 2D structures, doped nanocrystals, and, finally, as a point of comparison, organic molecules. We end with some conclusions and connections, including an outline of promising paths forward.

Temperature-Controlled Reversible Formation and Phase Transformation of 3D Nanocrystal Superlattices Through In Situ Small-Angle X-ray Scattering

For decades, the spontaneous organization of nanocrystals into superlattices has captivated the scientific community. However, achieving direct control over the formation of the superlattice and its phase transformations has proven to be a grand challenge, often resulting in the generation of multiple symmetries under the same experimental conditions. Here, we achieve direct control over the formation of the superlattice and its phase transformations by modulating the thermal energy of a nanocrystal dispersion without relying on solvent evaporation. We follow the temperature-dependent dynamics of the self-assembly process using synchrotron-based small-angle X-ray scattering. When cooled below -24.5 °C, lead sulfide nanocrystals form micrometer-sized three-dimensional phase-pure body-centered cubic superlattices. When cooled below -35.1 °C, these superlattices undergo a collective diffusionless phase transformation that yields denser body-centered tetragonal phases. These structural changes can be reversed by increasing the temperature of the dispersion and may lead to the direct modulation of the optical properties of these artificial solids.

Direct nano-imaging of light-matter interactions in nanoscale excitonic emitters

Strong light-matter interactions in localized nano-emitters placed near metallic mirrors have been widely reported via spectroscopic studies in the optical far-field. Here, we report a near-field nano-spectroscopic study of localized nanoscale emitters on a flat Au substrate. Using quasi 2-dimensional CdSe/Cd_xZn_1-xS nanoplatelets, we observe directional propagation on the Au substrate of surface plasmon polaritons launched from the excitons of the nanoplatelets as wave-like fringe patterns in the near-field photoluminescence maps. These fringe patterns were confirmed via extensive electromagnetic wave simulations to be standing-waves formed between the tip and the edge-up assembled nano-emitters on the substrate plane. We further report that both light confinement and in-plane emission can be engineered by tuning the surrounding dielectric environment of the nanoplatelets. Our results lead to renewed understanding of in-plane, near-field electromagnetic signal transduction from the localized nano-emitters with profound implications in nano and quantum photonics as well as resonant optoelectronics.

Photonically active bowtie nanoassemblies with chirality continuum

Chirality is a geometrical property described by continuous mathematical functions^1-5. However, in chemical disciplines, chirality is often treated as a binary left or right characteristic of molecules rather than a continuity of chiral shapes. Although they are theoretically possible, a family of stable chemical structures with similar shapes and progressively tuneable chirality is yet unknown. Here we show that nanostructured microparticles with an anisotropic bowtie shape display chirality continuum and can be made with widely tuneable twist angle, pitch, width, thickness and length. The self-limited assembly of the bowties enables high synthetic reproducibility, size monodispersity and computational predictability of their geometries for different assembly conditions⁶. The bowtie nanoassemblies show several strong circular dichroism peaks originating from absorptive and scattering phenomena. Unlike classical chiral molecules, these particles show a continuum of chirality measures² that correlate exponentially with the spectral positions of the circular dichroism peaks. Bowtie particles with variable polarization rotation were used to print photonically active metasurfaces with spectrally tuneable positive or negative polarization signatures for light detection and ranging (LIDAR) devices.

Frequency Stabilization and Optically Tunable Lasing in Colloidal Quantum Dot Superparticles

Self-assembled superparticles composed of colloidal quantum dots establish microsphere cavities that support optically pumped lasing from whispering gallery modes. Here, we report on the time- and excitation fluence-dependent lasing properties of CdSe/CdS quantum dot superparticles. Spectra collected under constant photoexcitation reveal that the lasing modes are not temporally stable but instead blue-shift by more than 30 meV over 15 min. To counter this effect, we establish a high-fluence light-soaking protocol that reduces this blue-shift by more than an order of magnitude to 1.7 ± 0.5 meV, with champion superparticles displaying mode blue-shifts of <0.5 meV. Increasing the pump fluence allows for optically controlled, reversible, color-tunable red-to-green lasing. Combining these two paradigms suggests that quantum dot superparticles could serve in applications as low-cost, robust, solution-processable, tunable microlasers.

Nanoparticle dynamics in hydrogel networks with controlled defects

The effect of nanoscale defects on nanoparticle dynamics in defective tetra-poly(ethylene glycol) (tetra-PEG) hydrogels is investigated using single particle tracking. In a swollen nearly homogeneous hydrogel, PEG-functionalized quantum dot (QD) probes with a similar hydrodynamic diameter (d_h = 15.1 nm) to the mesh size (〈ξ_s〉 = 16.3 nm), are primarily immobile. As defects are introduced to the network by reaction-tuning, both the percentage of mobile QDs and the size of displacements increase as the number and size of the defects increase with hydrolysis time, although a large portion of the QDs remain immobile. To probe the effect of nanoparticle size on dynamics in defective networks, the transport of d_h = 47.1 nm fluorescent polystyrene (PS) and d_h = 9.6 nm PEG-functionalized QDs is investigated. The PS nanoparticles are immobile in all hydrogels, even in highly defective networks with an open structure. Conversely, the smaller QDs are more sensitive to perturbations in the network structure with an increased percentage of mobile particles and larger diffusion coefficients compared to the larger QDs and PS nanoparticles. The differences in nanoparticle mobility as a function of size suggests that particles of different sizes probe different length scales of the defects, indicating that metrics such as the confinement ratio alone cannot predict bulk dynamics in these systems. This study provides insight into designing hydrogels with controlled transport properties, with particular importance for degradable hydrogels for drug delivery applications.

Nanocrystal Superparticles with Whispering-Gallery Modes Tunable through Chemical and Optical Triggers

Whispering-gallery microresonators have the potential to become the building blocks for optical circuits. However, encoding information in an optical signal requires on-demand tuning of optical resonances. Tuning is achieved by modifying the cavity length or the refractive index of the microresonator. Due to their solid, nondeformable structure, conventional microresonators based on bulk materials are inherently difficult to tune. In this work, we fabricate irreversibly tunable optical microresonators by using semiconductor nanocrystals. These nanocrystals are first assembled into colloidal spherical superparticles featuring whispering-gallery modes. Exposing the superparticles to shorter ligands changes the nanocrystal surface chemistry, decreasing the cavity length of the microresonator by 20% and increasing the refractive index by 8.2%. Illuminating the superparticles with ultraviolet light initiates nanocrystal photo-oxidation, providing an orthogonal channel to decrease the refractive index of the microresonator in a continuous fashion. Through these approaches, we demonstrate optical microresonators tunable by several times their free spectral range.

Sub-5 nm Anisotropic Pattern Transfer via Colloidal Lithography of a Self-Assembled GdF3 Nanocrystal Monolayer

Patterning materials with nanoscale features opens many research opportunities ranging from fundamental science to technological applications. However, current nanofabrication methods are ill-suited for sub-5 nm patterning and pattern transfer. We demonstrate the use of colloidal lithography to transfer an anisotropic pattern of discrete features into substrates with a critical dimension below 5 nm. The assembly of monodisperse, anisotropic nanocrystals (NCs) with a rhombic-plate morphology spaced by dendrimer ligands results in a well-ordered monolayer that serves as a 2D anisotropic hard mask pattern. This pattern is transferred into the underlying substrate using dry etching followed by removal of the NC mask. We exemplify this approach by fabricating an array of pillars with a rhombic cross-section and edge-to-edge spacing of 4.4 ± 1.1 nm. The fabrication approach enables broader access to patterning materials at the deep nanoscale by implementing innovative processes into well-established fabrication methods while minimizing process complexity.

Controlled deposition of nanoparticles with critical Casimir forces

Nanocrystal assembly represents the key fabrication step to develop next-generation optoelectronic devices with properties defined from the bottom-up. Despite numerous efforts, our limited understanding of nanoscale interactions has so far delayed the establishment of assembly conditions leading to reproducible superstructure morphologies, therefore hampering integration with large-scale, industrial processes. In this work, we demonstrate the deposition of a layer of semiconductor nanocrystals on a flat and unpatterned silicon substrate as mediated by the interplay of critical Casimir attraction and electrostatic repulsion. We show experimentally and rationalize with Monte Carlo and molecular dynamics simulations how this assembly process can be biased towards the formation of 2D layers or 3D islands and how the morphology of the deposited superstructure can be tuned from crystalline to amorphous. Our findings demonstrate the potential of the critical Casimir interaction to direct the growth of future artificial solids based on nanocrystals as the ultimate building blocks.

Debye vs. Casimir: controlling the structure of charged nanoparticles deposited on a substrate

Fine-tuning the interactions between particles can allow one to steer their collective behaviour and structure. A convenient way to achieve this is to use solvent criticality to control attraction, via critical Casimir forces, and to control repulsion via the Debye screening of electrostatic interactions. Herein, we develop a multiscale simulation framework and a method for controlled deposition of quantum dots to investigate how these interactions affect the structure of charged nanoparticles deposited on a substrate, altogether immersed in a binary liquid mixture intermixed with salt. We consider nanoparticles and substrates favouring the same component of the mixture and find that the critical Casimir interactions between the nanoparticles become drastically reduced at the substrate. In particular, the interactions can become a few k_BT weaker and their decay length a few orders of magnitude smaller than in the bulk. At off-critical compositions, the decay length increases upon approaching criticality, as expected, but the interaction strength decreases. With molecular dynamics simulations and experiments, we reveal that the nanoparticles can self-assemble into crystalline clusters which form superstructures resembling cluster fluids and spinodal morphology. The simulations additionally predict the formation of fractal-like nanoparticle gels and bicontinuous phases. Our results demonstrate that charged nanoparticles in a salty binary liquid mixture provide exciting opportunities to study the formation of complex structures experimentally and theoretically, which may lead to applications in optoelectronics and photonics.

Simultaneous Photonic and Excitonic Coupling in Spherical Quantum Dot Supercrystals

Semiconductor nanocrystals, or quantum dots (QDs), simultaneously benefit from inexpensive low-temperature solution processing and exciting photophysics, making them the ideal candidates for next-generation solar cells and photodetectors. While the working principles of these devices rely on light absorption, QDs intrinsically belong to the Rayleigh regime and display optical behavior limited to electric dipole resonances, resulting in low absorption efficiencies. Increasing the absorption efficiency of QDs, together with their electronic and excitonic coupling to enhance charge carrier mobility, is therefore of critical importance to enable practical applications. Here, we demonstrate a general and scalable approach to increase both light absorption and excitonic coupling of QDs by fabricating hierarchical metamaterials. We assemble QDs into crystalline supraparticles using an emulsion template and demonstrate that these colloidal supercrystals (SCs) exhibit extended resonant optical behavior resulting in an enhancement in absorption efficiency in the visible range of more than 2 orders of magnitude with respect to the case of dispersed QDs. This successful light trapping strategy is complemented by the enhanced excitonic coupling observed in ligand-exchanged SCs, experimentally demonstrated through ultrafast transient absorption spectroscopy and leading to the formation of a free biexciton system on sub-picosecond time scales. These results introduce a colloidal metamaterial designed by self-assembly from the bottom up, simultaneously featuring a combination of nanoscale and mesoscale properties leading to simultaneous photonic and excitonic coupling, therefore presenting the nanocrystal analogue of supramolecular structures.

Continuous Scan Strategy (CSS): A Novel Technique to Improve the Accuracy of Intraoral Digital Impressions

PURPOSE

To present the results obtained with the "Continuous Scan Strategy" (CSS), a direct intraoral scanning technique based on the connection of the implant scan bodies (SBs) with thermoplastic resin.

METHODS

40 patients were restored with 45 long-span monolithic implant-supported zirconia restorations (10 partial prostheses [PP] and 35 full arches [FA]) fabricated via a full-digital workflow after the capture of an intraoral impression (Trios3®) using the CSS technique. The primary outcomes were the marginal adaptation and passive fit of the superstructures, checked at T0 (intraoral try-in of polyurethane or metal replica of the final prosthesis) and T1 (delivery of the final zirconia restoration). The secondary outcomes, registered at T2 (2 years after the delivery of the final prosthesis), were implant survival, prosthetic success, and complications. A throughout statistical analysis was performed.

RESULTS

At T0, 40/45 replicas demonstrated a perfect passive fit and adaptation. At T1, one prosthesis had fractured, and at T2, an additional prosthesis had fractured and one had chipped. The implant survival rate was 100%. The prosthetic success was 93.3%.

CONCLUSIONS

CSS seems to represent a viable option for capturing accurate intraoral digital impressions for the fabrication of precise long-span implant-supported restorations.

Highly Stable Perovskite Supercrystals via Oil-in-Oil Templating

Inorganic perovskites display an enticing foreground for their wide range of optoelectronic applications. Recently, supercrystals (SCs) of inorganic perovskite nanocrystals (NCs) have been reported to possess highly ordered structure as well as novel collective optical properties, opening new opportunities for efficient films. Here, we report the large-scale assembly control of spherical, cubic, and hexagonal SCs of inorganic perovskite NCs through templating by oil-in-oil emulsions. We show that an interplay between the roundness of the cubic NCs and the tension of the confining droplet surface sets the superstructure morphology, and we exploit this interplay to design dense hyperlattices of SCs. The SC films show strongly enhanced stability for at least two months without obvious structural degradation and minor optical changes. Our results on the controlled large-scale assembly of perovskite NC superstructures provide new prospects for the bottom-up production of optoelectronic devices based on the microfluidic production of mesoscopic building blocks.

Controlling Superstructure-Property Relationships via Critical Casimir Assembly of Quantum Dots

The assembly of colloidal quantum dots (QDs) into dense superstructures holds great promise for the development of novel optoelectronic devices. Several assembly techniques have been explored; however, achieving direct and precise control over the interparticle potential that controls the assembly has proven to be challenging. Here, we exploit the application of critical Casimir forces to drive the growth of QDs into superstructures. We show that the exquisite temperature-dependence of the critical Casimir potential offers new opportunities to control the assembly process and morphology of the resulting QD superstructures. The direct assembly control allows us to elucidate the relation between structural, optical, and conductive properties of the critical Casimir-grown QD superstructures. We find that the choice of the temperature setting the interparticle potential plays a central role in maximizing charge percolation across QD thin-films. These results open up new directions for controlling the assembly of nanostructures and their optoelectronic properties.

Survival comparison in gastric cancer patients between 7th and 8th edition of the AJCC TNM staging system: The first western single center experience

BACKGROUND

The objective of this study was to compare the 7th and the 8th edition of American Joint Committee on Cancer staging system (AJCC TNM) in terms of better stratification in our gastric cancer resected patients.

METHODS AND MATERIALS

A retrospective analysis of a single western center series was made. Patients who underwent surgery from January 2004 to December 2016 were enrolled in the study. We compared survival rates across patients classified according to the 7th and the 8th AJCC TNM staging system.

RESULTS

Among 295 patients we observed 9.8% stage migration according the 8th edition. Of these 2.1% and 7.9% of patients showed respectively a higher and a lower stage. 5 years Overall Survival (5Y-OS) according to the 8th edition for stage IIIB and IIIC were 32% versus 9% showing a better stratification compared to the 7th edition in which 5Y-OS were respectively 26% versus 22%.

CONCLUSION

Restaging system seems to improve survival rate discrimination in particular comparing stage IIIB and stage IIIC; whereas in stage IIIA this is not so clear. More studies are necessary to confirm these data.

Revealing Driving Forces in Quantum Dot Supercrystal Assembly

The assembly of semiconductor nanoparticles, quantum dots (QDs), into dense crystalline nanostructures holds great promise for future optoelectronic devices. However, knowledge of the sub-nanometer scale driving forces underlying the kinetic processes of nucleation, growth, and final densification during QD assembly remains poor. Emulsion-templated assembly has recently been shown to provide good control over the bulk condensation of QDs into highly ordered 3D supercrystals. Here, emulsion-templated assembly is combined with in situ small-angle X-ray scattering to obtain direct insight into the nanoscale interactions underlying the nucleation, growth, and densification of QD supercrystals. At the point of supercrystal nucleation, nanoparticles undergo a hard-sphere-like crystallization into a hexagonal-close-packed lattice, slowly transforming into a face-centered-cubic lattice. The ligands play a crucial role in balancing steric repulsion against attractive van der Waals forces to mediate the initial equilibrium assembly, but cause the QDs to be progressively destabilized upon densification. The rich detail of this kinetic study elucidates the assembly and thermodynamic properties that define QD supercrystal fabrication approaching single-crystal quality, paving the way toward their use in optoelectronic devices.

Excitation-Dependent Photoluminescence from Single-Carbon Dots

Carbon dots (CDs) are carbon-based fluorescent nanoparticles that can exhibit excitation-dependent photoluminescence (PL) "tunable" throughout the entire visible range, interesting for optoelectronic and imaging applications. The mechanism underlying this tunable emission remains largely debated, most prominently being ascribed to dot-to-dot variations that ultimately lead to excitation-dependent ensemble properties. Here, single-dot spectroscopy is used to elucidate the origin of the excitation-dependent PL of CDs. It is demonstrated that already single CDs exhibit excitation-dependent PL spectra, similar to those of the CD ensemble. The single dots, produced by a facile one-step synthesis from chloroform and diethylamine, exhibit emission spectra with several characteristic peaks differing in emission peak position and spectral width and shape, indicating the presence of distinct emission sites on the CDs. Based on previous work, these emission sites are related to the sp² subregions in the carbon core, as well as the functional groups on the surface. These results confirm that it is possible to integrate and engineer different types of electronic transitions at the nanoscale on a single CD, making these CDs even more versatile than organic dyes or inorganic quantum dots and opening up new routes toward light-emission engineering.

Comparison of the Optical Properties of Graphene and Alkyl-terminated Si and Ge Quantum Dots

Semiconductor quantum dots are widely investigated due to their size dependent energy structure. In particular, colloidal quantum dots represent a promising nanomaterial for optoelectronic devices, such as photodetectors and solar cells, but also luminescent markers for biotechnology, among other applications. Ideal materials for these applications should feature efficient radiative recombination and absorption transitions, altogether with spectral tunability over a wide range. Group IV semiconductor quantum dots can fulfill these requirements and serve as an alternative to the commonly used direct bandgap materials containing toxic and/or rare elements. Here, we present optical properties of butyl-terminated Si and Ge quantum dots and compare them to those of graphene quantum dots, finding them remarkably similar. We investigate their time-resolved photoluminescence emission as well as the photoluminescence excitation and linear absorption spectra. We contemplate that their emission characteristics indicate a (semi-) resonant activation of the emitting channel; the photoluminescence excitation shows characteristics similar to those of a molecule. The optical density is consistent with band-to-band absorption processes originating from core-related states. Hence, these observations strongly indicate a different microscopic origin for absorption and radiative recombination in the three investigated quantum dot systems.

Repairing Nanoparticle Surface Defects

Solar devices based on semiconductor nanoparticles require the use of conductive ligands; however, replacing the native, insulating ligands with conductive metal chalcogenide complexes introduces structural defects within the crystalline nanostructure that act as traps for charge carriers. We utilized atomically thin semiconductor nanoplatelets as a convenient platform for studying, both microscopically and spectroscopically, the development of defects during ligand exchange with the conductive ligands Na₄SnS₄ and (NH₄)₄Sn₂S₆. These defects can be repaired via mild chemical or thermal routes, through the addition of L‐type ligands or wet annealing, respectively. This results in a higher‐quality, conductive, colloidally stable nanomaterial that may be used as the active film in optoelectronic devices.

Solvatochromism Unravels the Emission Mechanism of Carbon Nanodots

High quantum yield, photoluminescence tunability, and sensitivity to the environment are hallmarks that make carbon nanodots interesting for fundamental research and applications. Yet, the underlying electronic transitions behind their bright photoluminescence are strongly debated. Despite carbon-dot interactions with their environment should provide valuable insight into the emitting transitions, they have hardly been studied. Here, we investigate these interactions in a wide range of solvents to elucidate the nature of the electronic transitions. We find remarkable and systematic dependence of the emission energy and kinetics on the characteristics of the solvent, with strong response of the photoexcited dots to hydrogen bonding. These findings suggest that the fluorescence originates from the radiative recombination of a photoexcited electron migrated to surface groups with holes left in the valence band of the crystalline core. Furthermore, the results demonstrate the fluorescence tunability to inherently derive from dot-to-dot polydispersity, independent of solvent interactions.

Survival prognostic factors in patients undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy treatment: analysis from a single oncological center

Background

The aim of our study is to analyze survival, treatment-related morbidity, and safety in our experience of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

Methods

Sixty-four patients were treated. Survival curves were calculated according to the Kaplan-Meier method. Univariate and multivariate analyses were done, and Cox’s proportional hazard model was used to identify significant factors.

Results

Global 5-year overall survival was 55 %. Overall survival was also evaluated according to neutrophils to lymphocytes ratio and neutrophils to platelets ratio. Overall survival according to pre-operative serum albumin level shows a difference in the two groups (P < 0.05). We observed minor or no adverse events in 53 cases (89.8 %), while 3 patients (5.1 %) showed a grade III–IV complication and 3 post-operative deaths (5.1 %). Post-operative complication also influenced overall survival; patients in whom a minor complication occurred had a 3-year overall survival (OS) of 62 % vs. a 3-year OS of 28 % in patients who underwent a major complication (P < 0.1).

Conclusions

Hyperthermic intraperitoneal chemotherapy (HIPEC) could be a valid and feasible option for selected patients affected by gastrointestinal malignancies’ peritoneal carcinomatosis.

Pre-operative parameters could be evaluated to choose patient who could benefit from cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

The cortisol awakening response predicts subclinical depressive symptomatology in Mexican American adults

While childhood trauma appears to be a risk factor for the onset of depression and subclinical depressive symptomatology in Mexican Americans, the specific physiological mechanisms contributing to this relationship remain to be clarified. Stress-induced dysregulation of the Hypothalamic-Pituitary-Adrenal (HPA) axis is associated with depressive symptomatology in non-Hispanics. The current study assessed the extent to which the cortisol awakening response (CAR) predicts subclinical depressive symptomatology beyond the influence of childhood trauma in a sample of 55 Mexican American males and females ages 18-38 years, without a diagnosis of clinical depression. Participants were assessed for exposure to early trauma and current depressive symptomatology. Salivary cortisol samples were collected on two consecutive days at awakening, 30, 45, and 60 min thereafter, and again at 3 p.m., 6 p.m. and 9 p.m. Data were analyzed using general linear models with repeated measures at four morning time points, and again, at three afternoon and evening time points. Results indicated a significant Symptoms×Time interaction for the CAR(p<0.05). The Symptom×Time interaction was not significant for afternoon and evening cortisol concentrations. Moreover, subclinical symptomatology was associated with attenuation of the initial rise in CAR, after controlling for the total frequency of exposure to childhood traumas. Hierarchical analyses show attenuation of the initial rise in the CAR was the best predictor of greater subclinical depressive symptomatology beyond the influence of trauma, and independent of a current diagnosis of major depression in a sample of adult Mexican Americans.

Font adaptive word indexing of modern printed documents

We propose an approach for the word-level indexing of modern printed documents which are difficult to recognize using current OCR engines. By means of word-level indexing, it is possible to retrieve the position of words in a document, enabling queries involving proximity of terms. Web search engines implement this kind of indexing, allowing users to retrieve Web pages on the basis of their textual content. Nowadays, digital libraries hold collections of digitized documents that can be retrieved either by browsing the document images or relying on appropriate metadata assembled by domain experts. Word indexing tools would therefore increase the access to these collections. The proposed system is designed to index homogeneous document collections by automatically adapting to different languages and font styles without relying on OCR engines for character recognition. The approach is based on three main ideas: the use of Self Organizing Maps (SOM) to perform unsupervised character clustering, the definition of one suitable vector-based word representation whose size depends on the word aspect-ratio, and the run-time alignment of the query word with indexed words to deal with broken and touching characters. The most appropriate applications are for processing modern printed documents (17th to 19th centuries) where current OCR engines are less accurate. Our experimental analysis addresses six data sets containing documents ranging from books of the 17th century to contemporary journals.

Combined sedation with oral chlordemethyldiazepam and midazolam by nasal route in third molar surgery

AIM

This study was performed to evaluate the effects on the cardiocirculatory system, on perioperative anxiety and compliance of sedation with 2 benzodiazepines, chlordemethyldiazepam (CDDZ) a long acting oral drug for presedation and midazolam, a short acting drug, administered by nasal route to induce intraoperative sedation.

METHODS

Fifty randomized patients undergoing third molar extraction at the Dental Clinic, University of Padua, were preoperatively evaluated. Anxiety was evaluated through a visual, analogue, scale (VAS) of 10 cm, a questionnaire of adjectives called interval scale of anxiety response (ISAR) and the Newman test was applied to evaluate the changes in psychomotor functions. All patients were treated with 1 ml of oral CDDZ for presedation and midazolam by the nasal route for intraoperative sedation at doses of 1 mg in Group 1 (25 patients) and 2 mg in Group 2 (25 patients). In all patients preoperative cardiocirculatory parameters were evaluated and in the first 20 min after the beginning of intervention. At the end of intervention the Newman test was reapplied, anxiety and postoperative cardiocirculatory data were reevaluated and the quality of the intervention judged in an interview made 1 week after the intervention (quality of the sedation technique, perioperative pain intensity, assumption of analgesic drugs, swelling, amnesia etc. after intervention).

RESULTS

The treatment with 1 mg CDDZ + 2 mg midazolam by nasal route is the best association to slightly attenuate intra- and postoperative cardiocirculatory response, anxiety and to improve the quality of the treatment without interfering on the psychomotor response of patients at the time of the discharge.

CONCLUSION

To conclude, the sedative technique employed is easily applied by the dentist, and is safe, efficacious and well tolerated by patients.

Electron-beam tomography coronary calcium scores are superior to Framingham risk variables for predicting the measured proximal stenosis burden

Previous studies of electron-beam tomography (EBT) have correlated coronary calcium scores with simplistic visual estimates of disease severity. In a clinical trial designed to evaluate 2 treatment strategies in coronary artery disease (CAD) patients with low levels of high-density lipoprotein cholesterol, we used quantitative coronary angiography to measure composite proximal stenosis burden from the baseline coronary angiogram and assessed the traditional Framingham risk variables in 146 patients. Stenosis burden is the sum, per patient, of percent stenosis for the worst lesion found in each of 9 standard proximal coronary segments. EBT estimates of coronary calcium (Agatston score, calcium volume score) were obtained for 115 of these patients. Stenosis burden was correlated with the calcium scores and risk variables. The best traditional correlates of stenosis burden were smoking status (r = 0.31, p = 0.001), prior myocardial infarction (r = 0.24, p = 0.005), body mass index (r = 0.23, p = 0.005), pack-years smoking (r = 0.20, p = 0.05), and age (r = 0.17, p = 0.04). With adjustment for age, all these correlations improved (eg, body mass index x age [r = 0.28, p = 0.001]). In addition, total cholesterol x age (r = 0.22, p = 0.008), fibrinogen x age (r = 0.19, p = 0.03), and systolic blood pressure x age (r = 0.18, p = 0.03) became significant correlates. Spearman correlations of the calcium scores with stenosis burden were considerably greater (Agatston: r = 0.62, p <0.0001; calcium volume: r = 0.63, p <0.0001). In multivariate regression analysis, calcium score, body mass index, and history of myocardial infarction were independent correlates of stenosis burden (R(2) = 0.45). At a given point in time, the EBT coronary calcium scores are greatly superior to the Framingham risk factors in predicting the measured proximal stenosis burden. Agatston and calcium volume scores are comparably predictive of stenosis burden.

High-risk sexual behaviors among adolescents engaged through a street-based peer outreach program--(the Adolescent HIV Project)

On-the-street peer based programs can overcome barriers and successfully engage teens in HIV counseling and testing. This initiative combines on-the-street peer outreach with on-the-street HIV testing in a mobile counseling and testing van. A survey was conducted to measure HIV risk behaviors concern about HIV infection. In year one, the program engaged 1550 youth. Of these, 666 completed HIV counseling and testing. Only 18% indicated that they had not had unprotected sexual intercourse in the preceding year. Thirty-nine percent of the males and 52% of the females had caused or been pregnant. Sixty-six percent of the males and 53% of the females believed that they could become HIV infected. Fifty-three percent of the male and 75% of the female respondents had had a previous HIV test. However concern about HIV did not significantly decrease the prevalence of HIV risk behaviors. Peer outreach and on-the-street counseling and testing is a successful method of increasing HIV testing among high risk youth. Youth are concerned about HIV infection but that concern does not translated into a change in risk behaviors.

Quantification and measurement of human lens opacities using the lens opacity meter

Lens opacity was quantified in 85 cataractous patients, using a new instrument: the lens opacity meter 701 (LOM; Interzeag, Schlieren, Switzerland). Cataracts were classified as nuclear, cortical, subcapsular and mixed forms. Sensitivity, specificity and reproducibility of the results were evaluated by statistical analysis. Visual acuity was correlated with LOM values in patients with nuclear and mixed cataracts. Moreover, the instrument gave a good degree of reproducibility only in patients who presented these forms of lens opacities. Our findings demonstrate that the LOM 701 is able to detect and to measure only lens opacities which affect the central area of the lens.

[Oroantral communications. The gold foil method]

The Authors propose the method of the golden leave to close oro-antral communications. The main advantages offered by this technique are the following: 1) marked reduction of the previously observed loss of vertical height of the alveolar bone (7-8% of the original values); 2) the post-operative phase is, most of the time, uneventful.

Bendazac and benzydamine for treatment of cataract: individualized therapy by the "BLOA test"

It was found that two chemically very close Non-Steroid Antiinflammatory Drugs (NSAID), bendazac and benzydamine, were able to reduce the Biological Liquid Oxidant Activity (BLOA) in vitro (bendezac) and in vivo (bendazac and benzydamine). Four hundred and seven patients were treated with bendazac and 599 with benzydamine. After a single dose oral administration they effected a BLOA Reducing Activity (BRA) ranging from 5% to over 20% in about 40% of cataractous patients. When these drugs were able to reduce the BLOA, they showed anticataract activity in about 50% and about 90% of patients according to the extent of BRA, i.e., less than 20% and greater than or equal to 20% of the basal value. This fact suggests that the anticataract agent is not the original NSAID (prodrug) but a NSAID metabolite or an elicited endogenous compound which produced the BLOA reduction. Individual BLOA could be reduced in vivo by benzydamine or bendazac, by both or by neither of them. This finding may be accounted for by selective biotransformation of each patient's original NSAID into the antioxidant anticataract compound. However, other possible mechanisms of the anticataract activity beside antioxidant activity might take place, such as protein and membrane stabilization, together with a not yet defined activation of enzymes within the lens effecting the reversal of cataractous opacity. Several side effects were apparent in short and long term treatments. The final conclusion of our study is that bendazac at a dosage ten-fold lower than that used in the clinics is anticataract drug when orally administered to "BLOA test selected" patients, at least for short term treatment of young, otherwise healthy humans with cortical cataract.