High-power holmium laser versus thulium fiber laser for endoscopic enucleation of the prostate in patients with glands larger than 80 ml: Results from the Prostate Endoscopic EnucLeation study group.

Background: Endoscopic enucleation of the prostate (EEP) has gained acceptance as an equitable alternative to transurethral resection of the prostate for benign prostate hyperplasia (BPH). Our primary aim is to compare peri-operative outcomes of EEP using thulium fiber laser (TFL) against high-power holmium laser (HPHL) in hands of experienced surgeons for large prostates (≥80 ml in volume). Secondary outcomes were assess complications within 1 year of follow up. Materials and Methods: We retrospectively reviewed patients with benign prostatic hyperplasia who underwent EEP with TFL or HPHL in 13 centers (January 2019-January 2023). Patients with prostate volume ≥80 ml were included, while those with concomitant prostate cancer, previous prostate/urethral surgery, and pelvic radiotherapy were excluded. Results: Of 1,929 included patients, HPHL was utilized in 1,459 and TFL in 470. After propensity score matching (PSM) for baseline characteristics, 247 patients from each group were analyzed. Overall operative time (90 [70, 120] vs. 52.5 [39, 93] min, P < 0.001) and enucleation time (90 [70, 105] vs. 38 [25, 70] min, P < 0.001) were longer in the TFL group, with comparable morcellation time (13 [10, 19.5] vs. 13 [10, 16.5] min, P = 0.914). In terms of postoperative outcomes, there were no differences in 30-day complications such as acute urinary retention, urinary tract infection or sepsis. In the PSM cohort, univariable analyses showed that higher age, lower preoperative Qmax, higher preoperative PVRU, and longer operation time were associated with higher odds of postoperative incontinence, while 2-lobe enucleation had lower odds of incontinence compared to 3-lobe enucleation. Conclusions: This real-world study reaffirms that HPHL and TFL in large prostates are equally efficacious in terms of 30-day complications. TFL with the en-bloc technique has a shorter operative time which significantly improves short- and medium-term functional outcomes.

Aberrant miR-29 is a predictive feature of severe phenotypes in pediatric Crohn's disease.

Crohn's disease (CD) is a chronic inflammatory gut disorder. Molecular mechanisms underlying the clinical heterogeneity of CD remain poorly understood. MicroRNAs (miRNAs) are important regulators of gut physiology, and several have been implicated in the pathogenesis of adult CD. However, there is a dearth of large-scale miRNA studies for pediatric CD. We hypothesized that specific miRNAs uniquely mark pediatric CD. We performed small RNA-Seq of patient-matched colon and ileum biopsies from treatment-naive pediatric patients with CD (n = 169) and a control cohort (n = 108). Comprehensive miRNA analysis revealed 58 miRNAs altered in pediatric CD. Notably, multinomial logistic regression analysis revealed that index levels of ileal miR-29 are strongly predictive of severe inflammation and stricturing. Transcriptomic analyses of transgenic mice overexpressing miR-29 show a significant reduction of the tight junction protein gene Pmp22 and classic Paneth cell markers. The dramatic loss of Paneth cells was confirmed by histologic assays. Moreover, we found that pediatric patients with CD with elevated miR-29 exhibit significantly lower Paneth cell counts, increased inflammation scores, and reduced levels of PMP22. These findings strongly indicate that miR-29 upregulation is a distinguishing feature of pediatric CD, highly predictive of severe phenotypes, and associated with inflammation and Paneth cell loss.

Long-term drought promotes invasive species by reducing wildfire severity.

Anthropogenic climate change has increased the frequency of drought, wildfire, and invasions of non-native species. Although high-severity fires linked to drought can inhibit recovery of native vegetation in forested ecosystems, it remains unclear how drought impacts the recovery of other plant communities following wildfire. We leveraged an existing rainfall manipulation experiment to test the hypothesis that reduced precipitation, fuel load, and fire severity convert plant community composition from native shrubs to invasive grasses in a Southern California coastal sage scrub system. We measured community composition before and after the 2020 Silverado wildfire in plots with three rainfall treatments. Drought reduced fuel load and vegetation cover, which reduced fire severity. Native shrubs had greater prefire cover in added water plots compared to reduced water plots. Native cover was lower and invasive cover was higher in postfire reduced water plots compared to postfire added and ambient water plots. Our results demonstrate the importance of fuel load on fire severity and plant community composition on an ecosystem scale. Management should focus on reducing fire frequency and removing invasive species to maintain the resilience of coastal sage scrub communities facing drought. In these communities, controlled burns are not recommended as they promote invasive plants.

Conversational agents for depression screening: A systematic review.

OBJECTIVE: This work explores the advances in conversational agents aimed at the detection of mental health disorders, and specifically the screening of depression. The focus is put on those based on voice interaction, but other approaches are also tackled, such as text-based interaction or embodied avatars. METHODS: PRISMA was selected as the systematic methodology for the analysis of existing literature, which was retrieved from Scopus, PubMed, IEEE Xplore, APA PsycINFO, Cochrane, and Web of Science. Relevant research addresses the detection of depression using conversational agents, and the selection criteria utilized include their effectiveness, usability, personalization, and psychometric properties. RESULTS: Of the 993 references initially retrieved, 36 were finally included in our work. The analysis of these studies allowed us to identify 30 conversational agents that claim to detect depression, specifically or in combination with other disorders such as anxiety or stress disorders. As a general approach, screening was implemented in the conversational agents taking as a reference standardized or psychometrically validated clinical tests, which were also utilized as a golden standard for their validation. The implementation of questionnaires such as Patient Health Questionnaire or the Beck Depression Inventory, which are used in 65% of the articles analyzed, stand out. CONCLUSIONS: The usefulness of intelligent conversational agents allows screening to be administered to different types of profiles, such as patients (33% of relevant proposals) and caregivers (11%), although in many cases a target profile is not clearly of (66% of solutions analyzed). This study found 30 standalone conversational agents, but some proposals were explored that combine several approaches for a more enriching data acquisition. The interaction implemented in most relevant conversational agents is text-based, although the evolution is clearly towards voice integration, which in turns enhances their psychometric characteristics, as voice interaction is perceived as more natural and less invasive.

Validation of a Latin-American Spanish version of the Body Esteem Scale for Adolescents and Adults (BESAA-LA) in Colombian and Nicaraguan adults.

BACKGROUND: Body dissatisfaction (BD) is a growing concern in Latin America; reliable and culturally appropriate scales are necessary to support body image research in Spanish speaking Latin American countries. We sought to validate a Latin-American Spanish version of the Body Esteem Scale for Adolescents and Adults (BESAA; Mendelson et al. 2001). METHODS: The BESAA was translated, culturally adapted, and validated in a sample of adults in Colombia (N = 525, 65% women, Mage 24.4, SD = 9.28). We assessed factor structure (using confirmatory factor analysis (CFA), exploratory factor analysis (EFA) and exploratory structural equation model (ESEM)), internal reliability (using Cronbach's alpha and omega), validity (using the Body Appreciation Scale BAS and Sociocultural Attitudes Towards Appearance Questionnaire SATAQ), test-retest stability in a small subsample (N = 84, using Intraclass correlations ICC) and measurement invariance across gender. To evaluate the generalizability of the scale, we assessed reliability, validity, and factor structure in a second sample from rural Nicaragua (N = 102, 73% women, Mage 22.2, SD = 4.72), and assessed measurement invariance across Nicaraguan and Colombian participants. RESULTS: The scale showed good internal reliability and validity in both samples, and there was evidence of adequate test-retest stability in the Colombian sample. EFA showed a three-factor structure with subscales we labelled 'appearance-positive', 'appearance-negative' and 'weight', that was confirmed using CFA and ESEM in the Colombian sample. Measurement invariance was confirmed across the Colombian and Nicaraguan samples, and across gender within the Colombian sample. CONCLUSION: The Latin-American Spanish version of the BESAA (BESAA-LA) appears to be a psychometrically sound measure with good reliability, validity and invariance across gender and countries. These results support the use of this scale to measure body satisfaction/dissatisfaction in Latin American adult populations.

Draft Genome Sequence Resource of Erwinia sp. Strain INIA01, a Phytopathogen Isolated from a Diseased Stalk of Peruvian Maize.

Here, we report the complete genome sequence of Erwinia sp. strain INIA01, a bacterium isolated from lesions of Zea mays from northern Peru. This genome possesses two circular replicons, a 4.2-Mb chromosome, and a 438-kb plasmid.

Utility of a Short Neuropsychological Protocol for Detecting HIV-Associated Neurocognitive Disorders in Patients with Asymptomatic HIV-1 Infection.

Human Immunodeficiency Virus type 1 (HIV-1) infection is a chronic disease that affects ~40 million people worldwide. HIV-associated neurocognitive disorders (HAND) are common in individuals with HIV-1 Infection, and represent a recent public health problem. Here we evaluate the performance of a recently proposed short protocol for detecting HAND by studying 60 individuals with HIV-1-Infection and 60 seronegative controls from a Caribbean community in Barranquilla, Colombia. The short evaluation protocol used significant neuropsychological tests from a previous study of asymptomatic HIV-1 infected patients and a group of seronegative controls. Brief screening instruments, i.e., the Mini-mental State Examination (MMSE) and the International HIV Dementia Scale (IHDS), were also applied. Using machine-learning techniques, we derived predictive models of HAND status, and evaluated their performance with the ROC curves. The proposed short protocol performs exceptionally well yielding sensitivity, specificity, and overall prediction values >90%, and better predictive capacity than that of the MMSE and IHDS. Community-specific cut-off values for HAND diagnosis, based on the MMSE and IHDS, make this protocol suitable for HAND screening in individuals from this Caribbean community. This study shows the effectivity of a recently proposed short protocol to detect HAND in individuals with asymptomatic HIV-1-Infection. The application of community-specific cut-off values for HAND diagnosis in the clinical setting may improve HAND screening accuracy and facilitate patients' treatment and follow-up. Further studies are needed to assess the performance of this protocol in other Latin American populations.

A Rare Case of Endometriosis of the Small Bowel.

Endometriosis of the small bowel is a rare clinical event. The clinical condition presents with vague abdominal symptoms and is usually not diagnosed acutely, unless clinicians have a high index of suspicion. Most patients are diagnosed after multiple clinical encounters. We present a case of endometriosis causing small bowel obstruction diagnosed postsurgically.

Antimicrobial resistance of Escherichia coli isolates from spray‑chilled sheep carcasses during cooling / Resistencia antimicrobiana en aislados de Escherichia coli de canales de ovejas asperjadas durante la refrigeración / Resistência antimicrobiana de isolados de Escherichia coli de carcaças ovinas aspergidas durante o resfriamento

Abstract Background: Multidrug-resistant bacteria present in food of animal origin raise human and animal health concerns. Objective: To assess antimicrobial resistance of Escherichia coli isolates from sheep carcasses subjected to spray-chilling with water (4 and 10 hours) during cooling. Methods: Thirty surface swabs were collected from carcasses before and after the last water spray in two slaughter periods. In a first assessment (1st sampling), three spray-chilled carcasses (4 hours), three non-sprayed and one control carcass were sampled. In a second assessment (2nd sampling), the same number of carcasses and treatments were maintained, but spray-chilling was extended to 10 hours. All samples collected were isolated and submitted to susceptibility test using 16 (1st sampling) and 17 (2nd sampling) antimicrobials, respectively. Results: Overall, E. coli isolates were resistant most antimicrobials. Spray-chilled and control carcasses (10 hours) showed resistance to meropenem. Conclusion: E. coli isolates from carcasses subjected to spray-chilling with water for 10 hours had higher antimicrobial resistance to one, two, and four antimicrobial classes, characterizing a multidrug resistance profile. These results highlight the need to monitor health status throughout the meat production processes.

Resumen Antecedentes: las bacterias multirresistentes presentes en alimentos de origen animal son motivo de alerta para la salud humana y animal. Objetivo: verificar la resistencia a antimicrobianos de aislados de Escherichia coli en canales ovinas sometidas a aspersión (4 y 10 h) durante la refrigeración. Métodos: Luego de dos faenas de sacrificio, treinta hisopos fueron colectados en la superficie de las canales antes y después de la última aspersión. En un primer sacrificio (1era colecta) se recolectaron muestras de tres canales sometidas a aspersión (4 horas), tres sin aspersión y una canal como control. En un segundo sacrificio (2da colecta), el mismo número de canales y tratamientos se mantuvo, y el período de aspersión se extendió a 10 horas. Las muestras recogidas fueron aisladas y sometidas a la prueba de susceptibilidad utilizándo 16 (1.ª colecta) y 17 (2.ª colecta) antimicrobianos, respectivamente. Resultados: los aislamientos de E. coli fueron, en general, resistentes a las principales clases de antimicrobianos. Las canales con aspersión y el control (10 h) presentaron resistencia al meropenem. Conclusión: cuando la asperción duró 10 h, los aislados de E. coli presentaron mayor resistencia para una, dos y cuatro clases de antimicrobianos, es decir, fueron multirresistentes a los fármacos utilizados. Esto resalta la necesidad de monitorear el estado de salud durante todos los procesos de producción de carne.

Resumo Antecedentes: bactérias multirresistentes presentes em alimentos de origem animal são motivo de preocupação e alerta na saúde humana e animal. Objetivo: verificar a resistência antimicrobiana em isolados de Escherichia coli de carcaças de ovinos pulverizadas ou não (4 e 10 horas) durante a refrigeração. Métodos: foram coletados trinta swabs de superfície em carcaças antes e após a última aspersão em dois abates. Em outubro do 2015, três carcaças aspergidas foram amostradas, três sem aspersão e uma carcaça para controle, por um período de 4 horas. Em julho de 2016 (2ª coleta), o mesmo número de carcaças e tratamentos foram mantidos e o período de aspersão foi prolongado em 10 horas. As amostras coletadas foram isoladas e submetidas ao teste de susceptibilidade em 16 (1ª coleta) e 17 (2ª coleta) antimicrobianos, respectivamente. Resultados: isolados de E. coli foram, em geral, resistentes às principais classes de antimicrobianos. As carcaças e o controle aspergidos (10 h) apresentaram resistência ao meropenem. Conclusão: quando a aspersão de água durou 10 horas, os isolados de E. coli apresentaram maior resistência antimicrobiana a uma, duas e quatro classes de antimicrobianos, o que é uma multirresistência aos fármacos testados. Isso alerta para a necessidade de monitorar os aspectos de saúde durante todos os processos de produção de carne.

Smart conversational agents for the detection of neuropsychiatric disorders: A systematic review.

OBJECTIVE: To determine whether smart conversational agents can be used for detection of neuropsychiatric disorders. Therefore, we reviewed the technologies used, targeted mental disorders and validation procedures of relevant proposals in this field. METHODS: We searched Scopus, PubMed, Pro-Quest, IEEE Xplore, Web of Science, CINAHL and the Cochrane Library using a predefined search strategy. Studies were included if they focused on neuropsychiatric disorders and involved conversational data for detection and diagnosis. They were assessed for eligibility by independent reviewers and ultimately included if a consensus was reached about their relevance. RESULTS: 2356 references were initially retrieved. Eventually, 17 articles - referring 9 smart conversational agents - met the inclusion criteria. Out of the selected studies, 7 are targeted at neurocognitive disorders, 7 at depression and 3 at other conditions. They apply diverse technological solutions and analysis techniques (82.4% use Artificial Intelligence), and they usually rely on gold standard tests for criterion validity assessment. Acceptability, reliability and other aspects of validity were rarely addressed. CONCLUSION: The use of smart conversational agents for the detection of neuropsychiatric disorders is an emerging and promising field of research, with a broad coverage of mental disorders and extended use of AI. However, the few published studies did not undergo robust psychometric validation processes. Future research in this field would benefit from more rigorous validation mechanisms and standardized software and hardware platforms.

Utilization of Grafix for the Detection of Transient Interactors of Saccharomyces cerevisiae Spliceosome Subcomplexes.

Pre-mRNA splicing is a very dynamic process that involves many molecular rearrangements of the spliceosome subcomplexes during assembly, RNA processing, and release of the complex components. Glycerol gradient centrifugation has been used for the separation of protein or RNP (RiboNucleoProtein) complexes for functional and structural studies. Here, we describe the utilization of Grafix (Gradient Fixation), which was first developed to purify and stabilize macromolecular complexes for single particle cryo-electron microscopy, to identify interactions between splicing factors that bind transiently to the spliceosome complex. This method is based on the centrifugation of samples into an increasing concentration of a fixation reagent to stabilize complexes. After centrifugation of yeast total extracts loaded on glycerol gradients, recovered fractions are analyzed by dot blot for the identification of the spliceosome sub-complexes and determination of the presence of individual splicing factors.

Assessing the measurement invariance of a Latin-American Spanish translation of the Body Appreciation Scale-2 in Mexican, Argentinean, and Colombian adolescents.

In order to advance in the study of positive body image among different cultures, it is important to create culturally appropriate measures. We examined the psychometric properties of a Latin-American Spanish translation of the Body Appreciation Scale-2 (BAS-2; Tylka & Wood-Barcalow, 2015a), specifically assessing measurement invariance using a large sample of 3845 male and female adolescents from Argentina, Mexico, and Colombia. Participants completed the BAS-2, Eating Disorder Inventory-2, Male Body Attitude Scale and the Sociocultural Attitudes Toward Appearance Questionnaire-3. The BAS-2 had a unidimensional factor structure in each of the three samples. We confirmed the structural, metric, and scalar invariance of the scale regardless of gender or country. Adolescents in Argentina had lower body appreciation compared with those in Mexico and Colombia. Overall, females had lower body appreciation than males, with the greatest gender difference found in the Argentinean sample. Our findings strongly support the validity and reliability of this Latin-American translation of the BAS-2 in measuring positive body image in adolescents in Argentina, Mexico, and Colombia.

Geographic Object-Based Analysis of Airborne Multispectral Images for Health Assessment of Capsicum annuum L. Crops.

Vegetation health assessment by using airborne multispectral images throughout crop production cycles, among other precision agriculture technologies, is an important tool for modern agriculture practices. However, to really take advantage of crop fields imagery, specialized analysis techniques are needed. In this paper we present a geographic object-based image analysis (GEOBIA) approach to examine a set of very high resolution (VHR) multispectral images obtained by the use of small unmanned aerial vehicles (UAVs), to evaluate plant health states and to generate cropland maps for Capsicum annuum L. The scheme described here integrates machine learning methods with semi-automated training and validation, which allowed us to develop an algorithmic sequence for the evaluation of plant health conditions at individual sowing point clusters over an entire parcel. The features selected at the classification stages are based on phenotypic traits of plants with different health levels. Determination of areas without data dependencies for the algorithms employed allowed us to execute some of the calculations as parallel processes. Comparison with the standard normalized difference vegetation index (NDVI) and biological analyses were also performed. The classification obtained showed a precision level of about 95 % in discerning between vegetation and non-vegetation objects, and clustering efficiency ranging from 79 % to 89 % for the evaluation of different vegetation health categories, which makes our approach suitable for being incorporated at C. annuum crop's production systems, as well as to other similar crops. This methodology can be reproduced and adjusted as an on-the-go solution to get a georeferenced plant health estimation.

Perrogator: A Portable Energy-Efficient Interrogator for Dynamic Monitoring of Wavelength-Based Sensors in Wearable Applications.

In this paper, we report the development of a portable energy-efficient interrogator (Perrogator) for wavelength-based optical sensors. The interrogator is based on a compact solution encompassing a white light source and the spectral convolution between the sensor and a tunable filter, which is acquired by a photodetector, where a microcontroller has two functions: (i) To control the filter tuning and to (ii) acquire the photodetector signal. Then, the data is sent to a single-board computer for further signal processing. Furthermore, the employed single-board computer has a Wi-Fi module, which can be used to send the sensors data to the cloud. The proposed approach resulted in an interrogator with a resolution as high as 3.82 pm (for 15.64 nm sweeping range) and maximum acquisition frequency of about 210 Hz (with lower resolution ~15.30 pm). Perrogator was compared with a commercial fiber Bragg grating (FBG) interrogator for strain measurements and good agreement between both devices was found (1.226 pm/µÎµ for the commercial interrogator and 1.201 pm/µÎµ for the proposed approach with root mean square error of 0.0144 and 0.0153, respectively), where the Perrogator has the additional advantages of lower cost, higher portability and lower energy consumption. In order to demonstrate such advantages in conjunction with the high acquisition frequency allowed us to demonstrate two wearable applications using the proposed interrogation device over FBG and Fabry-Perot interferometer (FPI) sensors. In the first application, an FBG-embedded smart textile for knee angle assessment was used to analyze the gait of a healthy person. Due to the capability of reconstructing the FBG spectra, it was possible to employ a technique based on the FBG wavelength shift and reflectivity to decouple the effects of the bending angle and axial strain on the FBG response. The measurement of the knee angle as well as the estimation of the angular and axial displacements on the grating that can be correlated to the variations of the knee center of rotation were performed. In the second application, a FPI was embedded in a chest band for simultaneous measurement of breath and heart rates, where good agreement (error below 5%) was found with the reference sensors in all analyzed cases.

Polymethyl methacrylate (PMMA) recycling for the production of optical fiber sensor systems.

This paper proposes the recycling of poly (methyl methacrylate) plates, formerly used in LCD monitors to produce polymer optical fibers without cladding for sensor systems and a discussion about the fabrication process of the fiber cladding is briefly presented. After disassembling LCD monitors the acrylic plate is cleaned and submitted to an extrusion process. Extrusion temperatures of 220°C, 230°C and 240°C were applied, and the produced polymer fibers were characterized by infrared and visible spectrometry, as well as evaluated for thermal analysis through differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Furthermore, a refractive index sensor was developed with the recycled fibers. Results show that the recycled fiber refractive index sensor is linear (R2 = 0.99) and presents a sensitivity of more than 4 times higher when compared to a sensor using a commercial POF.

Low-Cost Interrogation Technique for Dynamic Measurements with FBG-Based Devices.

Fiber Bragg gratings are widely used optical fiber sensors for measuring temperature and/or mechanical strain. Nevertheless, the high cost of the interrogation systems is the most important drawback for their large commercial application. In this work, an in-line Fabry-Perot interferometer based edge filter is explored in the interrogation of fiber Bragg grating dynamic measurements up to 5 kHz. Two devices an accelerometer and an arterial pulse wave probe were interrogated with the developed approach and the results were compared with a commercial interrogation monitor. The data obtained with the edge filter are in agreement with the commercial device, with a maximum RMSE of 0.05 being able to meet the requirements of the measurements. Resolutions of 3.6 pm and 2.4 pm were obtained, using the optical accelerometer and the arterial pulse wave probe, respectively.

Probing the Sulfur-Modified Capping Layer of Gold Nanoparticles Using Surface Enhanced Raman Spectroscopy (SERS) Effects.

Gold nanoparticles (AuNP) exhibit particular plasmonic properties when stimulated by visible light, which makes them a promising tool to many applications in sensor technology and biomedical applications, especially when associated to sulfur-based compounds. Sulfur species form a great variety of self-assembled structures that cap AuNP and this interaction rules the optical and plasmonic properties of the system. Here, we report the behavior of citrate-stabilized gold nanospheres in two distinct sulfur colloidal solutions, namely, thiocyanate and sulfide ionic solutions. Citrate-capped gold nanospheres were characterized using ultraviolet-visible (UV-Vis) absorption, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). In the presence of sulfur species, we have observed the formation of NP clusters and chain-like structures, giving rise to surface-enhanced effects. Surface-enhanced Raman spectroscopy (SERS) pointed to a modification in citrate vibrational modes, which suggests substitution of citrate by either thiocyanate or sulfide ions with distinct dynamics, as showed by in situ fluorescence. Moreover, we report the emergence of surface-enhanced infrared absorption (SEIRA) effect, which corroborates SERS conclusions. Further, SEIRA shows a great potential as a tool for specification of sulfur compounds in colloidal solutions, which is particularly useful when dealing with sensor technology.

An Unusual Case of Posterior Reversible Encephalopathy Syndrome.

A 21-year-old pregnant female with no significant past medical history presented with acute onset headache and nausea as well as tonic-clonic seizures, then rapidly decompensated into a coma with complete absence of brainstem reflexes. The patient was ultimately diagnosed with hemolysis, elevated liver enzymes, and low platelets (HELLP syndrome) and subsequent posterior reversible encephalopathy syndrome (PRES) with brainstem involvement. Emergent delivery and blood pressure control resulted in rapid and complete neurologic recovery.

Envelope-based technique for liquid level sensors using an in-line fiber Mach-Zehnder interferometer.

This paper proposes a sensor interrogation technique based on the analysis of the overall spectrum envelope of an in-line Mach-Zehnder interferometer structure with three different fibers. The interference pattern created by a level sensor of 120 mm was evaluated with both the traditional and the proposed interrogation techniques. The result shows that the technique here proposed improves the sensitivity of the sensor by more than an order of magnitude. Moreover, our new interrogation technique allows the length of an in-line Mach-Zehnder interferometer to be extended up to 470 mm while maintaining high linearity and sensitivity.

Corrosion Resistant FBG-Based Quasi-Distributed Sensor for Crude Oil Tank Dynamic Temperature Profile Monitoring.

This article presents a corrosion resistant, maneuverable, and intrinsically safe fiber Bragg grating (FBG)-based temperature optical sensor. Temperature monitoring is a critical activity for the oil and gas industry. It typically involves acquiring the desired parameters in a hazardous and corrosive environment. The use of polytetrafluoroethylene (PTFE) was proposed as a means of simultaneously isolating the optical fiber from the corrosive environment and avoiding undesirable mechanical tensions on the FBGs. The presented sensor head is based on multiple FBGs inscribed in a lengthy single mode fiber. The sensor presents an average thermal sensitivity of 8.82 ± 0.09 pm/°C, resulting in a typical temperature resolution of ~0.1 °C and an average time constant value of 6.25 ± 0.08 s. Corrosion and degradation resistance were verified by infrared spectroscopy and scanning electron microscopy during 90 days exposure to high salinity crude oil samples. The developed sensor was tested in a field pilot test, mimicking the operation of an inland crude tank, demonstrating its abilities to dynamically monitor temperature profile.