Inkjet-printed high-performance and mechanically flexible organic photodiodes for optical wireless communication.

Emerging areas such as the Internet of Things (IoT), wearable and wireless sensor networks require the implementation of optoelectronic devices that are cost-efficient, high-performing and capable of conforming to different surfaces. Organic semiconductors and their deposition via digital printing techniques have opened up new possibilities for optical devices that are particularly suitable for these innovative fields of application. In this work, we present the fabrication and characterization of high-performance organic photodiodes (OPDs) and their use as an optical receiver in an indoor visible light communication (VLC) system. We investigate and compare different device architectures including spin-coated, partially-printed, and fully-printed OPDs. The presented devices exhibited state-of-the-art performance and reached faster detection speeds than any other OPD previously reported as organic receivers in VLC systems. Finally, our results demonstrate that the high-performance of the fabricated OPDs can be maintained in the VLC system even after the fabrication method is transferred to a fully-inkjet-printed process deposited on a mechanically flexible substrate. A comparison between rigid and flexible samples shows absolute differences of only 0.2 b s-1 Hz-1 and 2.9 Mb s-1 for the spectral efficiency and the data rate, respectively.

Side-emitting fiber-based distributed receiver for visible light communication uplink.

We present a distributed receiver for visible light communication based on a side-emitting optical fiber. We show that 500 kbps data rate can be captured with a bit-error rate below the forward-error correction limit of 3.8·10-3 with a light-emitting diode (LED) transmitter 25 cm away from the fiber, whereas by increasing the photodetector gain and reducing the data rate down to 50 kbps, we improve the LED-fiber distance significantly up to 4 m. Our results lead to a low-cost distributed visible-light receiver with a 360° field of view for indoor low-data rate, Internet of Things, and sensory networks.

General framework for calculating irradiance distributions of symmetric surface sources.

Symmetries in system modeling can be exploited to obtain analytical results on the system behavior and to speed up computations using the symmetric model. This work explores the use of symmetries in radiant surfaces for calculating the induced irradiance distributions by developing a general mathematical expression. The obtained model is applied to flat, cylindrical, and spherical sources to obtain explicit expressions. An experimental evaluation of the flat source is carried out and compared with a traditional point source, and the obtained procedure for the flat scenario is compared with the direct integration approach, which shows an improvement in the computation time of at least two orders of magnitude with a relative root mean square error of less than 10%. The results show that the proposed approach enhances short-range predictions for extended sources. To demonstrate the impact of this in optical wireless communications we have outlined a few applications.

Overview of Biofluids and Flow Sensing Techniques Applied in Clinical Practice.

This review summarizes the current knowledge on biofluids and the main flow sensing techniques applied in healthcare today. Since the very beginning of the history of medicine, one of the most important assets for evaluating various human diseases has been the analysis of the conditions of the biofluids within the human body. Hence, extensive research on sensors intended to evaluate the flow of many of these fluids in different tissues and organs has been published and, indeed, continues to be published very frequently. The purpose of this review is to provide researchers interested in venturing into biofluid flow sensing with a concise description of the physiological characteristics of the most important body fluids that are likely to be altered by diverse medical conditions. Similarly, a reported compilation of well-established sensors and techniques currently applied in healthcare regarding flow sensing is aimed at serving as a starting point for understanding the theoretical principles involved in the existing methodologies, allowing researchers to determine the most suitable approach to adopt according to their own objectives in this broad field.

Optical Technologies for the Improvement of Skin Cancer Diagnosis: A Review.

The worldwide incidence of skin cancer has risen rapidly in the last decades, becoming one in three cancers nowadays. Currently, a person has a 4% chance of developing melanoma, the most aggressive form of skin cancer, which causes the greatest number of deaths. In the context of increasing incidence and mortality, skin cancer bears a heavy health and economic burden. Nevertheless, the 5-year survival rate for people with skin cancer significantly improves if the disease is detected and treated early. Accordingly, large research efforts have been devoted to achieve early detection and better understanding of the disease, with the aim of reversing the progressive trend of rising incidence and mortality, especially regarding melanoma. This paper reviews a variety of the optical modalities that have been used in the last years in order to improve non-invasive diagnosis of skin cancer, including confocal microscopy, multispectral imaging, three-dimensional topography, optical coherence tomography, polarimetry, self-mixing interferometry, and machine learning algorithms. The basics of each of these technologies together with the most relevant achievements obtained are described, as well as some of the obstacles still to be resolved and milestones to be met.

Improvement of the signal-to-noise ratio in a low power self-mixing interferometer using a coupled interferometric effect.

We present experimental results of a low-emission self-mixing interferometer that uses a coupled interferometric effect to improve the signal produced by a vibrating target. This method is intended to be useful in applications where the target is prone to be damaged by high-intensity laser sources. The beam of a Fabry-Perot laser diode is split and ∼21% of the original emission is used to measure the harmonic micro-displacements of the target using the self-mixing effect. A portion of the residual beam, which also carries the interferometric information related to the target displacement, is reinjected back into the laser cavity by means of a fixed reflector, causing a second interferometric phenomenon that improves the signal-to-noise ratio of the measurement by up to ∼13 dB. A theoretical description of the phenomena is also proposed. Further, we apply this technique to the two most common self-mixing sensing schemes: internal photodiode and junction voltage. The reported results show good agreement with theory and prove the capability of the method to enhance the SNR in SMI schemes.

Impact of Personal Protective Equipment on Surgical Performance During the COVID-19 Pandemic.

BACKGROUND: The Severe Acute Respiratory Syndrome Coronavirus 2 pandemic has exposed surgeons to hazardous working conditions, imposing the need for personal protective equipment (PPE) use during surgery. The use of such equipment may affect their non-technical skills, augment fatigue, and affect performance. This study aimed to assess the surgeons' perceptions of the impact of wearing PPE during emergency surgery throughout the pandemic. METHODS: An international cooperation group conducted an anonymous online survey among surgeons from over 30 countries, to assess perceptions about the impact of PPE use on non-technical skills, overall comfort, decision making, and surgical performance during emergency surgery on COVID-19 patients. RESULTS: Responses to the survey (134) were received from surgeons based on 26 countries. The vast majority (72%) were males. More than half of the respondents (54%) felt that their surgical performance was hampered with PPE. Visual impairment was reported by 63%, whereas 54% had communication impediments. Less than half (48%) felt protected with the use of PPE, and the same proportion perceived that the use of such equipment influenced their decision making. Decreased overall comfort was cited by 66%, and 82% experienced increased surgical fatigue. CONCLUSIONS: Surgeons perceived impediment for both visibility and communication, and other non-technical skills while using PPE on emergency surgery in COVID-19 patients. Their perceived lack of protection and comfort and increased fatigue may have inhibited their optimal surgical performance. More attention should be placed in the design of more user-friendly equipment, given the possibility of a second wave of the pandemic.

Confocal flowmeter based on self-mixing interferometry for real-time velocity profiling of turbid liquids flowing in microcapillaries.

We propose a new confocal device for flow profiling in microcapillaries. A viewfinder system is developed using a visible light microscope, allowing focusing with high precision an 830 nm Fabry-Perot laser diode on a microchannel. By means of a novel confocal approach, the Doppler shift produced by the particles of a turbid liquid moving in the focal plane can be measured in real time using the well-known self-mixing effect. The resolution of this device is characterized in function of the full width at half maximum of the Gaussian frequency peak related to the self-mixing signal in the frequency domain. Velocity measurements for flow rates from 0.2 to 1.6 mL/min are presented, and the results demonstrate that the method reduces the phase noise and the effects of the out-of-focus particles, allowing straightforward flow profiling in microchannel structures.

Orientational and Folding Thermodynamics via Electric Dipole Moment Restraining.

The projection of molecular processes onto a small set of relevant descriptors, the so-called reaction coordinates or collective variables (CVs), is a technique nowadays routinely employed by the biomolecular simulation community. In this work, we implemented two CVs to manipulate the orientation (i.e., angle) (µâƒ—a) and magnitude (|µâƒ—|) of the electric dipole moment. In doing so, we studied the thermodynamics of water orientation under the application of external voltages and the folding of two polypeptides at zero-field conditions. The projection of the free-energy [potential of mean force (PMF)] along water orientation defined an upper limit of around 0.3 V for irrelevant thermodynamic effects. On the other hand, sufficiently strong µâƒ—a restraints applied on 12-alanine (Ala12) triggered structural effects because of the alignment of local dipoles; for lower restraints, a full-body rotation is achieved. The manipulation of |µâƒ—| produced strong perturbations on the secondary structure of Ala12, promoting an enhanced sampling to its configurational space. Rigorous free-energy calculations in the form of 2-D PMFs for deca-alanine showed the utility of |µâƒ—| as a reaction coordinate to study folding in small α helices. As a whole, we propose that the manipulation of both components of the dipole moment, µâƒ—a and |µâƒ—|, provides thermodynamics insights into the structural conformation and stability of biomolecules. These new CVs are implemented in the Colvars module, available for NAMD and LAMMPS.

Introduction and evaluation of the ACS BCon basic course in Zaragoza, Spain.

BACKGROUND: The American College of Surgeons Bleeding Control Basic (BCon) course aimed at teaching hemorrhage control techniques in the USA had not yet been taught in Spain. The purpose of this study is to assess its implementation among students and healthcare employees in the Lozano Blesa University Hospital of Zaragoza, a middle-sized Spanish city. METHODS: The study was conducted in a University Hospital and at the University of Zaragoza, scheduling four free B-Con sessions from 2017 to 2018. Two groups were identified as forming the population: healthcare employees and medical students. An anonymous questionnaire was completed at the end of the course regarding content, applicability, usefulness, relevance, and satisfaction. Study variables were ranked from 0 to 10: poor (when graded from 0 to 3), fair (4 to 6) and good (7 to 10). Results were compared between the groups, expressed in percentages and χ2 tested to analyze significant differences if any. RESULTS: Among the 83 individuals who completed the course, 46 were medical students and 37 healthcare employees; 61% women and 39% men; aged 21 years to 52 years. Attendees evaluated satisfaction with the highest grade (84%), followed by usefulness (73%), applicability (70%), and relevance (66%). There was no variable graded as poor. The comparison of perceptions between groups did not reveal statistical differences based on a 0.05 significance level. CONCLUSION: We concluded that the B-Con course was valued as good for relevance, usefulness, applicability, and satisfaction by the majority of the studied population. LEVEL OF EVIDENCE: Level III.

A Complementary Metal Oxide Semiconductor Process-Compatible Ferroelectric Tunnel Junction.

In recent years, experimental demonstration of ferroelectric tunnel junctions (FTJ) based on perovskite tunnel barriers has been reported. However, integrating these perovskite materials into conventional silicon memory technology remains challenging due to their lack of compatibility with the complementary metal oxide semiconductor process (CMOS). This communication reports the fabrication of an FTJ based on a CMOS-compatible tunnel barrier Hf0.5Zr0.5O2 (6 unit cells thick) on an equally CMOS-compatible TiN electrode. Analysis of the FTJ by grazing angle incidence X-ray diffraction confirmed the formation of the noncentrosymmetric orthorhombic phase (Pbc21, ferroelectric phase). The FTJ characterization is followed by the reconstruction of the electrostatic potential profile in the as-grown TiN/Hf0.5Zr0.5O2/Pt heterostructure. A direct tunneling current model across a trapezoidal barrier was used to correlate the electronic and electrical properties of our FTJ devices. The good agreement between the experimental and theoretical model attests to the tunneling electroresistance effect (TER) in our FTJ device. A TER ratio of ∼15 was calculated for the present FTJ device at low read voltage (+0.2 V). This study suggests that Hf0.5Zr0.5O2 is a promising candidate for integration into conventional Si memory technology.

Microcantilever Displacement Measurement Using a Mechanically Modulated Optical Feedback Interferometer.

Microcantilever motion detection is a useful tool for the characterization of the physical, chemical and biological properties of materials. In the past, different approaches have been proposed and tested to enhance the behavior, size and simplicity of microcantilever motion detectors. In this paper, a new approach to measure microcantilever motion with nanometric resolution is presented. The proposed approach is based on the concept of mechanically-modulated optical feedback interferometry, a technique that has shown displacement measurement capabilities well within the nanometric scale and that, due to its size, compactness and low cost, may be a suitable choice for measuring nanometric motions in cantilever-like sensors. It will be shown that the sensor, in its current state of development, is capable of following a cantilever sinusoidal trajectory at different sets of frequencies ranging up to 200 Hz and peak to peak amplitudes up to λ / 2 with experimental resolutions in the λ / 100 range.

Current Developments on Optical Feedback Interferometry as an All-Optical Sensor for Biomedical Applications.

Optical feedback interferometry (OFI) sensors are experiencing a consistent increase in their applications to biosensing due to their contactless nature, low cost and compactness, features that fit very well with current biophotonics research and market trends. The present paper is a review of the work in progress at UPC-CD6 and LAAS-CNRS related to the application of OFI to different aspects of biosensing, both in vivo and ex vivo. This work is intended to present the variety of opportunities and potential applications related to OFI that are available in the field. The activities presented are divided into two main sensing strategies: The measurement of optical path changes and the monitoring of flows, which correspond to sensing strategies linked to the reconstruction of changes of amplitude from the interferometric signal, and to classical Doppler frequency measurements, respectively. For optical path change measurements, measurements of transient pulses, usual in biosensing, together with the measurement of large displacements applied to designing palliative care instrumentation for Parkinson disease are discussed. Regarding the Doppler-based approach, progress in flow-related signal processing and applications in real-time monitoring of non-steady flows, human blood flow monitoring and OFI pressure myograph sensing will be presented. In all cases, experimental setups are discussed and results presented, showing the versatility of the technique. The described applications show the wide capabilities in biosensing of the OFI sensor, showing it as an enabler of low-cost, all-optical, high accuracy biomedical applications.

Extraction of vibration parameters from optical feedback interferometry signals using wavelets.

This paper proposes the use of the wavelet transform as a technique that is suited for fringe detection and analysis of optical feedback interferometry (OFI) signals, thus allowing the retrieval of extremely small physical motion phenomena. A novel algorithm based on wavelet transform is used to process the OFI signal simultaneously in the time and frequency domains, enabling precise detection of signal fringes and, thus, the extraction of amplitude features of the vibrating target with error in the order of 0.1λ. Furthermore, using a complex Morlet wavelet as an analyzing wavelet enables us to extract important information from the time envelope of the OFI signal. Such an envelope can be useful in detecting fringes even in the presence of speckle reducing the error in a displacement reconstruction. Examples of OFI applications, including nanometric displacement sensing without direction ambiguity as well as the measurement of the frequency and velocity of vibrating targets and the detection in time of no periodic events, are also presented using this wavelet approach.

Efecto de la técnica de baño de dializado sobre el bacillus cereus en papa y su riesgo de intoxicación alimentaria / Impact of dialysate technique on bacillus cereus in potato and risk of food poisoning

Introducción: el baño de dializado es una técnica que facilita la extracción del potasio de la papa, Alimento utilizado en la terapia nutricional para pacientes renales, debido a su aporte de energía y escasa contribución proteica. El objetivo de este trabajo fue conocer el contenido microbiológico de Bacillus cereus en la papa y el efecto del baño de dializado. Materiales y métodos: se realizó el recuento microbiológico de la papa previo al baño de dializado, al finalizar las 6 horas del baño de dializado, luego de la cocción por ebullición (100ºC; 20 minutos), después de la cocción en horno (180-200ºC; 54 minutos) y posteriormente finalizado el enfriamiento a temperatura ambiente durante 3 horas. Resultados: se obtuvo un recuento de 7,5 x 105 UFC/g en la papa lavada y pelada; 2,9 x 108 UFC/g finalizado el baño de dializado; 2,6 x 106 UFC/g luego de la cocción por ebullición y posterior enfriamiento a temperatura ambiente >109 UFC/g. En relación a la cocción en horno y enfriado a temperatura ambiente, el recuento fue <105 UFC/g. La presencia de por lo menos 105-106 UFC/g de Bacillus cereus en el alimento es considerado significativo para el diagnóstico de intoxicación alimentaria. Conclusiones: el baño de dializado aumenta el número de UFC/g de alimento de Bacillus cereus y a pesar de consumir inmediatamente la papa luego de la cocción por ebullición, no es un alimento seguro para el consumidor inmunodeprimido. Sin embargo, la papa cocida en horno es el método más seguro para el consumo.

Introduction: dialysate bath is a technique allowing potassium extraction from foods such as potatoes in renal patients on kidney diet due to its energy intake and scarce protein contribution. The aim of this paper was to determine the microbiological content of Bacillus cereus in potatoes and the effect of dialysate bath. Materials and methods: the microbiological count of potato was performed before dialysate bath, once the 6-hour dialysate bath was finished, after boiling (100°C; 20 minutes), after oven baking (180-200ºC; 54 minutes) and finally after cooling at room temperature for 3 hours. Results: a count of 7.5 x 105 UFC/g was obtained in washed and peeled potatoes; 2.9 x 108 UFC/g after dialysate bath was finished; 2,6 x 106 UFC/g after boiling and subsequent cooling at room temperature>109 UFC/g. With respect to oven baking and subsequent cooling at room temperature, count was<105 UFC/g. The presence of at least 105-106 UFC/g of Bacillus cereus in food is considered significant for diagnosing food poisoning. Conclusions: dialysate bath increases the number of UFC/g of food of Bacillus cereus in spite of immediate potato consumption after boiling; it is not safe food for the immunosuppressed consumer. However, oven baking is the safest method for consuming potatoes.

Structural and thermochemical chemisorption of CO2 on Li(4+x)(Si(1-x)Al(x))O4 and Li(4-x)(Si(1-x)V(x))O4 solid solutions.

Different Li(4)SiO(4) solid solutions containing aluminum (Li(4+x)(Si(1-x)Al(x))O(4)) or vanadium (Li(4-x)(Si(1-x)V(x))O(4)) were prepared by solid state reactions. Samples were characterized by X-ray diffraction and solid state nuclear magnetic resonance. Then, samples were tested as CO(2) captors. Characterization results show that both, aluminum and vanadium ions, occupy silicon sites into the Li(4)SiO(4) lattice. Thus, the dissolution of aluminum is compensated by Li(1+) interstitials, while the dissolution of vanadium leads to lithium vacancies formation. Finally, the CO(2) capture evaluation shows that the aluminum presence into the Li(4)SiO(4) structure highly improves the CO(2) chemisorption, and on the contrary, vanadium addition inhibits it. The differences observed between the CO(2) chemisorption processes are mainly correlated to the different lithium secondary phases produced in each case and their corresponding diffusion properties.

Chemical composition and antibacterial activity of the essential oil of Lantana camara var. moritziana.

The essential oil obtained from the leaves of Lantana camara var. moritziana (Otto & Dietr.) López-Palacios collected at Rubio, Táchira State, Venezuela, was obtained by hydrodistillation in a Clevenger trap (0.1% yield). The oil was analyzed by gas chromatography-mass spectrometry (GC/MS) on HP GC-MS System, model 5973, identifying 33 compounds (97.1%) of which the major components were germacrene D (31.0%), followed by beta-caryophyllene (14.8%), a-phellandrene (6.7%), limonene (5.7%) and 1,8-cineole (5.2%). Evaluation of the antibacterial activity by agar diffusion method with discs against international reference bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Salmonella Typhi, Pseudomonas aeruginosa) showed growing inhibition of E. faecalis and S. aureus at MIC of 350 mg/mL and 400 mg/mL, respectively.

Curvature inversion technique: a novel tuboplastic technique for patulous Eustachian tube--a preliminary report.

OBJECTIVE: To assess the laser-assisted curvature inversion technique for the treatment of patients with patulous Eustachian tube (PET). STUDY DESIGN: Case series with planned data collection. SETTING: Tertiary care medical center. SUBJECTS AND METHODS: Eleven patients with Eustachian tube dysfunction underwent laser-assisted curvature inversion technique (CIT) of the medial and lateral lamina of the Eustachian tube. A KTP laser is used to cross-hatch the medial and lateral lamina of the tube to modify the curvature and to alter the spring of the posterior cushion. A change in the direction of the cartilaginous structure curvature is created to promote full closure of the patulous gap without interfering with the tube's muscular activity. None of the patients had any concurrent disease or additional surgical procedure. RESULTS: There were no surgical complications. Following CIT, subjective symptoms of autophony on nasal breathing improved in 9 of 11 patients (81.8%), while voice autophony improved in 8 patients (72.7%); posterior cushion curvature became inverted and less wide, and the valve was seen more closed postoperatively on simple endoscopy and slow-motion video-endoscopic analysis. On otoscopy, abnormal tympanic membrane excursions disappeared in 10 of 11 patients (90.9%). Mean immittance changes in tympanometric measurements for the forced respiration conditions improved postoperatively at least 0.05 mmhos in 9 of 11 patients (81.1%; P = .015). The follow-up period was 24 months. CONCLUSION: CIT appears to be a promising and relatively feasible technique for the treatment of PET.