Epidemiologia da anafilaxia no Brasil: Registro Brasileiro de Anafilaxia (RBA) da Associação Brasileira de Alergia e Imunologia (ASBAI) / Epidemiology of anaphylaxis in Brazil: The Brazilian Registry of Anaphylaxis (RBA) of the Brazilian Association of Allergy and Immunology (ASBAI)

INTRODUÇÃO: A anafilaxia é uma reação alérgica multissistêmica grave, de início agudo e potencialmente fatal. Poucos são os dados sobre sua epidemiologia no Brasil. O Registro Brasileiro de Anafilaxia da Associação Brasileira de Alergia e Imunologia (RBAASBAI) teve como objetivo ampliar o conhecimento sobre anafilaxia em indivíduos brasileiros. MÉTODOS: Estudo observacional transversal com questionário online sobre dados demográficos, desencadeantes suspeitos, manifestações clínicas, atendimento durante a reação, investigação diagnóstica e aconselhamento após a reação de pacientes que experimentaram uma reação anafilática. RESULTADOS: Entre junho/2021 e abril/2023, foram incluídos 237 pacientes (131 femininos): 99 crianças/adolescentes; 127 adultos e 11 idosos. Houve predomínio de meninos entre crianças/adolescentes (55,5%), e de mulheres entre os adultos (64,5%), e mediana de idade de 22 anos (< 1 a 77 anos). As manifestações cutâneas (92,8%) foram as mais frequentes, seguidas pelas respiratórias (70,1%), gastrointestinais (52,3%), neurológicas (36,3%) e cardiovasculares (35,3%). Os principais desencadeantes foram: alimentos (43,0%), medicamentos (26,2%), himenópteros (21,6%) e látex (2,5%); os alimentos entre crianças (leite, ovo, amendoim/castanhas), e os fármacos (anti-inflamatórios e antibióticos) entre os adultos. Quanto ao tratamento, 61,1% recebeu adrenalina (52,7% por profissional e 8,4% via autoinjetor de adrenalina -AIA). Uma adolescente (12 anos) faleceu após picada de abelha. A maioria recebeu plano escrito de emergência (78,1%) e foi ensinada a usar o AIA (70%). CONCLUSÃO: Os alimentos foram os desencadeantes mais comuns entre crianças/adolescentes, e os fármacos entre adultos brasileiros. A adrenalina continua sendo subutilizada, reforçando a necessidade de maior disseminação do tratamento adequado da anafilaxia.

INTRODUCTION: Anaphylaxis is a life-threatening, acute, severe multisystem allergic reaction.There is little data on its epidemiology in Brazil. The Brazilian Anaphylaxis Registry of the Brazilian Association of Allergy and Immunology (RBA-ASBAI) was devised to expand knowledge about anaphylaxis in Brazilian individuals. METHODS: Cross-sectional observational study using an online questionnaire to collect data on demographics, suspected triggers, clinical manifestations, treatment during the reaction, diagnostic workup, and post-reaction counseling in patients who have experienced an anaphylactic reaction. RESULTS: Between June 2021 and April 2023, 237 patients were included (131 female): 99 children/adolescents (<18yo), 127 adults (18-64yo), and 11 older adults (65-77yo). There was a male predominance in the pediatric group (55.5%), while females were predominant among adults (64.5%). The median age was 22 years (range, <1 to 77). The most frequent clinical manifestations were cutaneous (92.8%), followed by respiratory (70.1%), gastrointestinal (52.3%), neurological (36.3%), and cardiovascular (35.3%). The most common triggers were foods (43.0%), drugs (26.2%), venoms (21.6%), and latex (2.5%). Foods (milk, egg, peanuts/tree nuts) predominated among children, versus drugs (mostly nonsteroidal anti-inflammatory drugs and antibiotics) among adults. Regarding treatment, 61.1% received epinephrine (52.7% by a healthcare professional and 8.4% via epinephrine auto-injector [EAI]). One teenager (12yo) died due to a bee sting. Most patients received a written emergency plan (78.1%) and were taught how to use the EAI (70%). CONCLUSION: Foods were the most common triggers of anaphylaxis among Brazilian children and adolescents, while drugs predominated among adults. Epinephrine continues to be underused, highlighting the need for greater awareness of proper treatment of anaphylaxis.

Post-processing of real-time quantum event measurements for an optimal bandwidth.

Single electron tunneling and its transport statistics have been studied for some time using high precision charge detectors. However, this type of detection requires advanced lithography, optimized material systems and low temperatures (mK). A promising alternative, recently demonstrated, is to exploit an optical transition that is turned on or off when a tunnel event occurs. High bandwidths should be achievable with this approach, although this has not been adequately investigated so far. We have studied low temperature resonance fluorescence from a self-assembled quantum dot embedded in a diode structure. We detect single photons from the dot in real time and evaluate the recorded data only after the experiment, using post-processing to obtain the random telegraph signal of the electron transport. This is a significant difference from commonly used charge detectors and allows us to determine the optimal time resolution for analyzing our data. We show how this post-processing affects both the determination of tunneling rates using waiting-time distributions and statistical analysis using full-counting statistics. We also demonstrate, as an example, that we can analyze our data with bandwidths as high as 175 kHz. Using a simple model, we discuss the limiting factors for achieving the optimal bandwidth and propose how a time resolution of more than 1 MHz could be achieved.

Pushing the Limits in Real-Time Measurements of Quantum Dynamics.

Time-resolved studies of quantum systems are the key to understanding quantum dynamics at its core. The real-time measurement of individual quantum numbers as they switch between certain discrete values, well known as a "random telegraph signal," is expected to yield maximal physical insight. However, the signal suffers from both systematic errors, such as a limited time resolution and noise from the measurement apparatus, as well as statistical errors due to a limited amount of data. Here we demonstrate that an evaluation scheme based on factorial cumulants can reduce the influence of such errors by orders of magnitude. The error resilience is supported by a general theory for the detection errors as well as experimental data of single-electron tunneling through a self-assembled quantum dot. Thus, factorial cumulants push the limits in the analysis of random telegraph data, which represent a wide class of experiments in physics, chemistry, engineering, and life sciences.

Digital health for optimal supportive care in oncology: benefits, limits, and future perspectives.

BACKGROUND: Digital health provides solutions that capture patient-reported outcomes (PROs) and allows symptom monitoring and patient management. Digital therapeutics is the provision to patients of evidence-based therapeutic interventions through software applications aimed at prevention, monitoring, management, and treatment of symptoms and diseases or for treatment optimization. The digital health solutions collecting PROs address many unmet needs, including access to care and reassurance, increase in adherence and treatment efficacy, and decrease in hospitalizations. With current developments in oncology including increased availability of oral drugs and reduced availability of healthcare professionals, these solutions offer an innovative approach to optimize healthcare resource utilization. DESIGN: This scoping review clarifies the role and impact of the digital health solutions in oncology supportive care, with a view of the current segmentation according to their technical features (connection to sensors, PRO collection, remote monitoring, self-management in real time…), and identifies evidence from clinical studies published about their benefits and limitations and drivers and barriers to adoption. A qualitative summary is presented. RESULTS: Sixty-six studies were identified and included in the qualitative synthesis. Studies supported the use of 38 digital health solutions collecting ePROs and allowing remote monitoring, with benefits to patients regarding symptom reporting and management, reduction in symptom distress, decrease in unplanned hospitalizations and related costs and improved quality of life and survival. Among those 38 solutions 21 provided patient self-management with impactful symptom support, improvement of QoL, usefulness and reassurance. Principal challenges are in developing and implementing digital solutions to suit most patients, while ensuring patient compliance and adaptability for use in different healthcare systems and living environments. CONCLUSIONS: There is growing evidence that digital health collecting ePROs provide benefits to patients related to clinical and health economic endpoints. These digital solutions can be integrated into routine supportive care in oncology practice to provide improved patient-centered care.

Optical Detection of Single-Electron Tunneling into a Semiconductor Quantum Dot.

The maximum information of a dynamic quantum system is given by real-time detection of every quantum event, where the ultimate challenge is a stable, sensitive detector with high bandwidth. All physical information can then be drawn from a statistical analysis of the time traces. We demonstrate here an optical detection scheme based on the time-resolved resonance fluorescence on a single quantum dot. Single-electron resolution with high signal-to-noise ratio (4σ confidence) and high bandwidth of 10 kHz make it possible to record the individual quantum events of the transport dynamics. Full counting statistics with factorial cumulants gives access to the nonequilibrium dynamics of spin relaxation of a singly charged dot (γ_{↑↓}=3 ms^{-1}), even in an equilibrium transport measurement.

Craniomaxillofacial morphology alterations in children, adolescents and adults with neurofibromatosis 1: A cone beam computed tomography analysis of a Brazilian sample.

BACKGROUND: Oral manifestations are common in neurofibromatosis 1 (NF1), and include jaws and teeth alterations. Our aim was to investigate the craniomaxillofacial morphology of Brazilian children, adolescents and adults with NF1 using cone beam computed tomography. MATERIAL AND METHODS: This study was conducted with 36 Brazilian individuals with NF1 with ages ranging from 4 to 75. The participants were submitted to anamnesis, extra and intraoral exam and cephalometric analysis using cone beam computed tomography. Height of the NF1 individuals was compared to the length of jaws and skull base. The results of the cephalometric measurements of the NF1 group were compared with a control group paired by age, gender and skin color. RESULTS: Individuals with NF1 had lower maxillary length (p<0.0001), lower mandibular length (p<0.0001), lower skull base length (p<0.0001). In children and adolescents, the mandible was more posteriorly positioned (p=0.01), when compared with the control group. There was no association between jaws and skull base length with the height of the individuals with NF1. CONCLUSIONS: Brazilian children, adolescents and adults with NF1 have short mandible, maxilla and skull base. Moreover, children and adolescents present mandibular retrusion.

Clinicopathologic characteristics associated with long-term survival in advanced epithelial ovarian cancer: an NRG Oncology/Gynecologic Oncology Group ancillary data study.

OBJECTIVE: To identify clinicopathologic factors associated with 10-year overall survival in epithelial ovarian cancer (EOC) and primary peritoneal cancer (PPC), and to develop a predictive model identifying long-term survivors. METHODS: Demographic, surgical, and clinicopathologic data were abstracted from GOG 182 records. The association between clinical variables and long-term survival (LTS) (>10years) was assessed using multivariable regression analysis. Bootstrap methods were used to develop predictive models from known prognostic clinical factors and predictive accuracy was quantified using optimism-adjusted area under the receiver operating characteristic curve (AUC). RESULTS: The analysis dataset included 3010 evaluable patients, of whom 195 survived greater than ten years. These patients were more likely to have better performance status, endometrioid histology, stage III (rather than stage IV) disease, absence of ascites, less extensive preoperative disease distribution, microscopic disease residual following cyoreduction (R0), and decreased complexity of surgery (p<0.01). Multivariable regression analysis revealed that lower CA-125 levels, absence of ascites, stage, and R0 were significant independent predictors of LTS. A predictive model created using these variables had an AUC=0.729, which outperformed any of the individual predictors. CONCLUSIONS: The absence of ascites, a low CA-125, stage, and R0 at the time of cytoreduction are factors associated with LTS when controlling for other confounders. An extensively annotated clinicopathologic prediction model for LTS fell short of clinical utility suggesting that prognostic molecular profiles are needed to better predict which patients are likely to be long-term survivors.

IL-15 super-agonist (ALT-803) enhances natural killer (NK) cell function against ovarian cancer.

OBJECTIVE: Natural killer (NK) cells represent a powerful immunotherapeutic target as they lyse tumors directly, do not require differentiation, and can elicit potent inflammatory responses. The objective of these studies was to use an IL-15 super-agonist complex, ALT-803 (Altor BioScience Corporation), to enhance the function of both normal and ovarian cancer patient derived NK cells by increasing cytotoxicity and cytokine production. METHODS: NK cell function from normal donor peripheral blood mononuclear cells (PBMCs) and ovarian cancer patient ascites was assessed using flow cytometry and chromium release assays ±ALT-803 stimulation. To evaluate the ability of ALT-803 to enhance NK cell function in vivo against ovarian cancer, we used a MA148-luc ovarian cancer NOD scid gamma (NSG) xenogeneic mouse model with transferred human NK cells. RESULTS: ALT-803 potently enhanced functionality of NK cells against all ovarian cancer cell lines with significant increases seen in CD107a, IFNγ and TNFα expression depending on target cell line. Function was also rescued in NK cells derived from ovarian cancer patient ascites. Finally, only animals treated with intraperitoneal ALT-803 displayed an NK dependent significant decrease in tumor. CONCLUSIONS: ALT-803 enhances NK cell cytotoxicity against ovarian cancer in vitro and in vivo and is able to rescue functionality of NK cells derived from ovarian cancer patient ascites. These findings suggest that ALT-803 has the potential to enhance NK cell-based immunotherapeutic approaches for the treatment of ovarian cancer.

Optical Blocking of Electron Tunneling into a Single Self-Assembled Quantum Dot.

Time-resolved resonance fluorescence (RF) is used to analyze electron tunneling between a single self-assembled quantum dot (QD) and an electron reservoir. In equilibrium, the RF intensity reflects the average electron occupation of the QD and exhibits a gate voltage dependence that is given by the Fermi distribution in the reservoir. In the time-resolved signal, however, we find that the relaxation rate for electron tunneling is, surprisingly, independent of the occupation in the charge reservoir-in contrast to results from all-electrical transport measurements. Using a master equation approach, which includes both the electron tunneling and the optical excitation or recombination, we are able to explain the experimental data by optical blocking, which also reduces the electron tunneling rate when the QD is occupied by an exciton.

Comorbidity indices for clinical trials: adaptation of two existing indices for use with the FREEDOM trial in women with postmenopausal osteoporosis.

UNLABELLED: Two comorbidity indices were adapted for use in the FREEDOM trial and significantly correlated with the number of medications and impaired health status at baseline. The indices have applications for the analysis of clinical trial data and would allow for the appropriate adjustment of comorbidities when evaluating clinical trial outcomes. INTRODUCTION: The purpose of this study is to adapt two published comorbidity indices for use with the FREEDOM clinical trial evaluating postmenopausal women with osteoporosis. METHODS: FREEDOM enrolled women aged 60-90 years with a bone mineral density T-score <-2.5 at the lumbar spine or total hip and ≥-4.0 at both sites. Comorbidity indices were calculated using methods described by Sangha (Arthritis Rheum 49:156-163, 2003) and Wolfe (J Rheumatol 37:305-315, 2010) following modification. The adapted Sangha index included 12 conditions with a summary score of 0-12; the adapted Wolfe index included 7 conditions with a weighted summary score of 0-8. Higher scores indicated greater comorbidity. A panel of clinicians independently reviewed subjects' medical histories using a systematic process based on Medical Dictionary for Regulatory Activities (MedDRA) preferred terms to map specified comorbid conditions. Spearman correlations between the adapted indices and baseline subject characteristics expected to be associated with comorbidities were examined. RESULTS: Of the 7808 subjects in this study, 74 % had ≥1 comorbidities based on the adapted Sangha or Wolfe comorbidity indices. The mean (SD) adapted Sangha and Wolfe comorbidity indices were 1.4 (1.2) and 1.4 (1.3), respectively. Both indices correlated positively with age, body mass index, and the number of medications (r = 0.54 to 0.55) at baseline and inversely correlated with health-related quality of life (r = -0.22 to -0.30) (all P < 0.0001). Further, when either the adapted Sangha or Wolfe index was included as a covariate for assessing mortality over 36 months in the FREEDOM population, the hazard ratio of the comorbidity index indicated that the mortality risk increased by 27 or 28 %, respectively, for each unit increase in the adapted index (both P < 0.0001). CONCLUSIONS: Our work suggests these comorbidity indices may be adapted for use with clinical trial data, thereby allowing for the appropriate adjustment and reporting of covariates in the evaluation of clinical trial outcomes in an osteoporotic population.

Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells.

Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia colicells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficientE. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out.

Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells

Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia colicells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficientE. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out.

Oral manifestations of neurofibromatosis type 1 in children with facial plexiform neurofibroma: report of three cases.

Neurofibromatosis type 1 (NF1) is a common autosomal genetic disorder with a prevalence of 1 in 3,000 births. NF1 is a complex syndrome characterized by many abnormalities and may affect all organ systems. Oral manifestations of NF1 occur frequently, but reports including NF1 children with facial plexiform neurofibromas and oral alterations are scant. Facial plexiform neurofibroma may cause asymmetry, disfigurement and usually arises from the trigeminal nerve. The aim of this paper is to to report three pediatric NF1 cases with facial plexiform neurofibroma presenting with oral manifestations, which were evaluated clinically and radiographically, and also to briefly review the literature. Patients presented with changes in the oral soft tissues, jaws, and teeth ipsilateral to the tumor.

Effect of denosumab on bone mineral density and biochemical markers of bone turnover: 8-year results of a phase 2 clinical trial.

UNLABELLED: In a phase 2 study, continued denosumab treatment for up to 8 years was associated with continued gains in bone mineral density and persistent reductions in bone turnover markers. Denosumab treatment was well tolerated throughout the 8-year study. INTRODUCTION: The purpose of this study is to present the effects of 8 years of continued denosumab treatment on bone mineral density (BMD) and bone turnover markers (BTM) from a phase 2 study. METHODS: In the 4-year parent study, postmenopausal women with low BMD were randomized to receive placebo, alendronate, or denosumab. After 2 years, subjects were reallocated to continue, discontinue, or discontinue and reinitiate denosumab; discontinue alendronate; or maintain placebo for two more years. The parent study was then extended for 4 years where all subjects received denosumab. RESULTS: Of the 262 subjects who completed the parent study, 200 enrolled in the extension, and of these, 138 completed the extension. For the subjects who received 8 years of continued denosumab treatment, BMD at the lumbar spine (N = 88) and total hip (N = 87) increased by 16.5 and 6.8 %, respectively, compared with their parent study baseline, and by 5.7 and 1.8 %, respectively, compared with their extension study baseline. For the 12 subjects in the original placebo group, 4 years of denosumab resulted in BMD gains comparable with those observed during the 4 years of denosumab in the parent study. Reductions in BTM were sustained over the course of continued denosumab treatment. Reductions also were observed when the placebo group transitioned to denosumab. Adverse event profile was consistent with previous reports and an aging cohort. CONCLUSION: Continued denosumab treatment for 8 years was associated with progressive gains in BMD, persistent reductions in BTM, and was well tolerated.

International consensus on (ICON) pediatric asthma.

Asthma is the most common chronic lower respiratory disease in childhood throughout the world. Several guidelines and/or consensus documents are available to support medical decisions on pediatric asthma. Although there is no doubt that the use of common systematic approaches for management can considerably improve outcomes, dissemination and implementation of these are still major challenges. Consequently, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), recently formed by the EAACI, AAAAI, ACAAI, and WAO, has decided to propose an International Consensus on (ICON) Pediatric Asthma. The purpose of this document is to highlight the key messages that are common to many of the existing guidelines, while critically reviewing and commenting on any differences, thus providing a concise reference. The principles of pediatric asthma management are generally accepted. Overall, the treatment goal is disease control. To achieve this, patients and their parents should be educated to optimally manage the disease, in collaboration with healthcare professionals. Identification and avoidance of triggers is also of significant importance. Assessment and monitoring should be performed regularly to re-evaluate and fine-tune treatment. Pharmacotherapy is the cornerstone of treatment. The optimal use of medication can, in most cases, help patients control symptoms and reduce the risk for future morbidity. The management of exacerbations is a major consideration, independent of chronic treatment. There is a trend toward considering phenotype-specific treatment choices; however, this goal has not yet been achieved.

Dietetic management in gastrointestinal complications from antimalignant chemotherapy.

Antineoplastic chemotherapy (CT) represents the systemic treatment of malignant tumors. It can be used alone or combined with surgery and / or radiotherapy. The cytotoxic agents used in chemotherapy work on both cancerous cells and noncancerous cells of the body, generally resulting in high toxicity. The biological aggressiveness of chemotherapy particularly affects rapidly replicating cells, such as those of the digestive tract, resulting in adverse effects that impair food intake, leading to compromised nutritional status and which may lead to cachexia. The main toxic effects of chemotherapy in the gastrointestinal tract include nausea, vomiting -these are the most frequent- constipation, diarrhea, xerostomia, mucositis, dysphagia and anorexia. Given the high frequency of such effects, nutritional intervention should be an integral part of cancer treatment, to maintain and/or improve the patient's nutritional status and reduce or minimize the side effects caused by treatment. Accordingly, the goal of this study is to review dietetic conduct in the process of caring for patients undergoing cancer chemotherapy.

Transport spectroscopy of non-equilibrium many-particle spin states in self-assembled quantum dots.

Self-assembled quantum dots (QDs) are prominent candidates for solid-state quantum information processing. For these systems, great progress has been made in addressing spin states by optical means. In this study, we introduce an all-electrical measurement technique to prepare and detect non-equilibrium many-particle spin states in an ensemble of self-assembled QDs at liquid helium temperature. The excitation spectra of the one- (QD hydrogen), two- (QD helium) and three- (QD lithium) electron configuration are shown and compared with calculations using the exact diagonalization method. An exchange splitting of 10 meV between the excited triplet and singlet spin states is observed in the QD helium spectrum. These experiments are a starting point for an all-electrical control of electron spin states in self-assembled QDs above liquid helium temperature.

Optical properties of heavily doped GaAs nanowires and electroluminescent nanowire structures.

We present GaAs electroluminescent nanowire structures fabricated by metal organic vapor phase epitaxy. Electroluminescent structures were realized in both axial pn-junctions in single GaAs nanowires and free-standing nanowire arrays with a pn-junction formed between nanowires and substrate, respectively. The electroluminescence emission peak from single nanowire pn-junctions at 10 K was registered at an energy of around 1.32 eV and shifted to 1.4 eV with an increasing current. The line is attributed to the recombination in the compensated region present in the nanowire due to the memory effect of the vapor-liquid-solid growth mechanism. Arrayed nanowire electroluminescent structures with a pn-junction formed between nanowires and substrate demonstrated at 5 K a strong electroluminescence peak at 1.488 eV and two shoulder peaks at 1.455 and 1.519 eV. The main emission line was attributed to the recombination in the p-doped GaAs. The other two lines correspond to the tunneling-assisted photon emission and band-edge recombination in the abrupt junction, respectively. Electroluminescence spectra are compared with the micro-photoluminescence spectra taken along the single p-, n- and single nanowire pn-junctions to find the origin of the electroluminescence peaks, the distribution of doping species and the sharpness of the junctions.

XeF(2) gas-assisted focused-electron-beam-induced etching of GaAs with 30 nm resolution.

We demonstrate the gas-assisted focused-electron-beam (FEB)-induced etching of GaAs with a resolution of 30 nm at room temperature. We use a scanning electron microscope (SEM) in a dual beam focused ion beam together with xenon difluoride (XeF(2)) that can be injected by a needle directly onto the sample surface. We show that the FEB-induced etching with XeF(2) as a precursor gas results in isotropic and smooth etching of GaAs, while the etch rate depends strongly on the beam current and the electron energy. The natural oxide of GaAs at the sample surface inhibits the etching process; hence, oxide removal in combination with chemical surface passivation is necessary as a strategy to enable this high-resolution etching alternative for GaAs.