Charge-transfer dynamics in van der Waals heterojunctions formed by thiophene-based semiconductor polymers and exfoliated franckeite investigated from resonantly core-excited electrons.

Organic/inorganic van der Waals heterojunctions formed by a combination of 2D materials with semiconductor polymer films enable the fabrication of new device architectures that are interesting for electronic and optoelectronic applications. Here, we investigated the charge-transfer dynamics at the interface between 2D layered franckeite (Fr) and two thiophene-based conjugated polymers (PFO-DBT and P3HT) from the resonantly core-excited electron. The unoccupied electronic states of PFO-DBT/Fr and P3HT/Fr heterojunctions were studied using near-edge X-ray absorption fine structure (NEXAFS) and resonant Auger (RAS) synchrotron-based spectroscopies. We found evidence of ultrafast (subfemtosecond charge-transfer times) interfacial electron delocalization pathways from specific electronic states. For the interface between the PFO-DBT polymer and exfoliated franckeite, the most efficient interfacial electron delocalization pathways were found through π*(S-N) and π*(S-C) electronic states corresponding to the benzothiadiazole and thiophene units. On the other hand, for the P3HT polymer, we found that electrons excited to π-π* and S1s-π*(C-C) electronic states of the P3HT polymer are the most affected by the presence of exfoliated franckeite and consequently are the main interfacial electron-transfer pathways in this heterojunction. Our results have important implications in understanding how ultrafast electron delocalization is taking place in organic/inorganic van der Waals heterojunctions, which is relevant information in designing new devices involving these systems.

Edge phonons in black phosphorus.

Black phosphorus has recently emerged as a new layered crystal that, due to its peculiar and anisotropic crystalline and electronic band structures, may have important applications in electronics, optoelectronics and photonics. Despite the fact that the edges of layered crystals host a range of singular properties whose characterization and exploitation are of utmost importance for device development, the edges of black phosphorus remain poorly characterized. In this work, the atomic structure and behaviour of phonons near different black phosphorus edges are experimentally and theoretically studied using Raman spectroscopy and density functional theory calculations. Polarized Raman results show the appearance of new modes at the edges of the sample, and their spectra depend on the atomic structure of the edges (zigzag or armchair). Theoretical simulations confirm that the new modes are due to edge phonon states that are forbidden in the bulk, and originated from the lattice termination rearrangements.

Efficient graphene saturable absorbers on D-shaped optical fiber for ultrashort pulse generation.

We demonstrated a method to construct high efficiency saturable absorbers based on the evanescent light field interaction of CVD monolayer graphene deposited on side-polished D-shaped optical fiber. A set of samples was fabricated with two different core-graphene distances (0 and 1 µm), covered with graphene ranging between 10 and 25 mm length. The mode-locking was achieved and the best pulse duration was 256 fs, the shortest pulse reported in the literature with CVD monolayer graphene in EDFL. As result, we find a criterion between the polarization relative extinction ratio in the samples and the pulse duration, which relates the better mode-locking performance with the higher polarization extinction ratio of the samples. This criterion also provides a better understanding of the graphene distributed saturable absorbers and their reproducible performance as optoelectronic devices for optical applications.

Pulse generation and propagation in dispersion-managed ultralong erbium-doped fiber lasers mode-locked by carbon nanotubes.

We present a study of pulse generation and propagation in erbium-doped fiber lasers with cavity length varying from 8 m to 3.5 km. We demonstrate that soliton effect determines the pulse stabilization in ultralong cavities, measuring pulses with an average 7.0 ps pulsewidth for cavity lengths between 2.25 and 3.5 km. We also demonstrate that, by filling fundamental soliton requirements, pulsewidth can be determined by length and total dispersion cavity parameters.

Towards local motion detection by the use of analog self electro-optic effect device.

We demonstrated the use of the analog self electro-optic effect device (SEED) as part of an artificial retina chip for the detection and estimation of local motion. The characterization was performed by comparing our chip to biological and computational models and to other artificial retina chips. Its main unique feature is the optical output, since most chips have electrical output. By combining the response of the chip with temporal information about the input image, it is possible to estimate the velocity perpendicular to an edge, including its direction.

[Quality of life in childhood epilepsy]. / Qualidade de vida na epilepsia infantil.

Epilepsy is a chronic disorder in which onset occurs primarily during childhood and adolescence. Traditionally, treatment of childhood epilepsy emphasizes neurologic aspects over psychological factors. The attention to the seizure control in the clinical setting will not address the full range of quality of life problems of childhood epilepsy. Many of the psychosocial difficulties that plague adults with epilepsy develop from the complications associated with this early onset. Children with epilepsy have a high prevalence of behavior problems and learning problems. Assessing quality of life in pediatric epilepsy is especially important because children are in critical periods of development during which many cognitive and social skills are being learned. This study presents a simplified inventory of quality of life, with cultural, personal, social and relationship aspects. This investigation makes possible to the professional knowledge about children and a best direction of their conducts.

[Simplified inventory of quality of life in childhood epilepsy: initial results]. / Inventário simplificado de qualidade de vida na epilepsia infantil: primeiros resultados.

PURPOSE: To check how parents realize the quality of life of their epileptic children and if the relationship is controlled by their beliefs about epilepsy. METHODS: It has been applied 21 protocols of "Simplified inventory of quality of life in childhood epilepsy" to parents of children aged between 6-14 years old with benign childhood epilepsy. RESULTS: It was observed that 86% of parents reported beliefs about epilepsy. The majority of parents evaluated their children's quality of life as very good, but reported difficulties to deal with them. Behaviors of overprotection (62%) and feelings of worry, fear and insecurity (90%) were observed. The children were evaluated as irritated (52%), dependents (38%), overwroughts and inquiets (38%). About school, 33% are in special schools and have difficulties of academic and relationship. CONCLUSION: It was verified a lot of beliefs and acknowledgement seem to control parent's behavior on the way of dealing with epileptic children producing inadequate behaviors, in spite of realizing the quality of life of their children as been very good.

[Feelings and behaviors of parents of children with epilepsy]. / Sentimentos e reações de pais de crianças epilépticas.

PURPOSE: To assess the efficacy of support groups in identifying parents feelings and behaviors facing the diagnosis of epilepsy in their children. METHODS: Protocols were applied to 18 parents before and after the sessions. Each protocol consisted of questions concerning feelings and beliefs toward epilepsy as well as children-parent interactions. RESULTS: The following feelings were observed: disappointment (94.4%), fear (72.2%), frightening (27.8%), sadness (33.3%), anxiety (27.8%) and rejection (38.9%). These feelings were associated with overprotection (83.3%) and a lack of limits (38.9%). Parents reported feeling of safety after seizure control and 77.8% associate major of difficulties to the lack of information and the inadequate beliefs involved. After support sessions, 94.4% of the parents reported less anxiety. CONCLUSION: Support groups dispel misconception, clarify child parent relationships and prevent behavioral difficulties.

Association of a temporomandibular disorder and Eagle's syndrome: case report.

We report a clinical case of Eagle's syndrome which required dental intervention due to the presence of exacerbated symptoms indicating an association with a temporomandibular disorder. The therapeutic dental procedures used were an occlusal splint and temporary removable partial dentures. Surgical removal of the styloid process on the left side was later performed as a medical option.

Wavelength-division multiplexing with femtosecond pulses.

We demonstrate wavelength-division multiplexing with a single broadband femtosecond source by slicing the 3.7-THz spectral bandwidth of 85-fs laser pulses into 16 channels that are modulated individually.

Low-loss intracavity AlAs/AlGaAs saturable Bragg reflector for femtosecond mode locking in solid-state lasers.

We introduce a new low-loss semiconductor structure for femtosecond intracavity mode locking in low-gain solidstate lasers. This monolithic device can be engineered to exhibit specif ic saturation characteristics desirable for mode locking solid-state lasers. Self-starting 90-fs pulses are obtained with Ti:sapphire and diode-pumped Cr:LiSAF lasers. We discuss mode-locking mechanisms in quantum-well passively mode-locked solid-state lasers.

Self-linearized analog differential self-electro-optic-effect device.

We describe, demonstrate, and characterize an analog self-electro-optic-effect device that gives a difference between two optical output powers that is linearly proportional to an electrical or an optical drive. Such a device should permit bipolar (positive and negative) processing in novel image processing arrays. The device is able to operate over a range of more than 4 orders of magnitude of optical power from 50 nW to 2.5 mW, corresponding to uniform incident intensities as low as 3.3 mW/cm(2). The frequency response (3-dB limit) varies linearly from 7 kHz at 1-µW absorber power to 3.5 MHz at 1 mW of absorbed powers.

Analog differential self-linearized quantum-well self-electro-optic-effect modulator.

We describe an analog self-electro-optic-effect device that gives a difference between two optical output powers that is linearly proportional to electrical or optical drive, permitting bipolar processing in novel image-processing arrays. The device is able to operate over a range of more than four orders of magnitude optical power, from 50 nW to 2.5 mW, corresponding to uniform incident intensities as low as 3.3 mW/cm(2).

Testicular schistosomiasis mansoni: a differential diagnostic problem with testicular neoplasias.

We report a case of testicular schistosomiasis mansoni that was surgically treated as a tumor. Massive enlargement of the testicle (twice the original volume) was due to an extensive granulomatous reaction.