A Critical Review of the Propagation Models Employed in LoRa Systems.

LoRa systems are emerging as a promising technology for wireless sensor networks due to their exceptional range and low power consumption. The successful deployment of LoRa networks relies on accurate propagation models to facilitate effective network planning. Therefore, this review explores the landscape of propagation models supporting LoRa networks. Specifically, we examine empirical propagation models commonly employed in communication systems, assessing their applicability across various environments such as outdoor, indoor, and within vegetation. Our investigation underscores the prevalence of logarithmic decay in most empirical models. In addition, we survey the relationship between model parameters and environmental factors, clearing their nuanced interplay. Analyzing published measurement results, we extract the log-distance model parameters to decipher environmental influences comprehensively. Drawing insights from published measurement results for LoRa, we compare them with the model's outcomes, highlighting successes and limitations. We additionally explore the application of multi-slope models to LoRa measurements to evaluate its effectiveness in enhancing the accuracy of path loss prediction. Finally, we propose new lines for future research in propagation modelling to improve empirical models.

Non-Contact Vision-Based Techniques of Vital Sign Monitoring: Systematic Review.

The development of non-contact techniques for monitoring human vital signs has significant potential to improve patient care in diverse settings. By facilitating easier and more convenient monitoring, these techniques can prevent serious health issues and improve patient outcomes, especially for those unable or unwilling to travel to traditional healthcare environments. This systematic review examines recent advancements in non-contact vital sign monitoring techniques, evaluating publicly available datasets and signal preprocessing methods. Additionally, we identified potential future research directions in this rapidly evolving field.

Urinary Equol and Equol-Predicting Microbial Species Are Favorably Associated With Cardiometabolic Risk Markers in Chinese Adults.

BACKGROUND: The association between soy isoflavones intake and cardiometabolic health remains inconclusive. We investigated the associations of urinary biomarkers of isoflavones including daidzein, glycitein, genistein, equol (a gut microbial metabolite of daidzein), and equol-predicting microbial species with cardiometabolic risk markers. METHODS AND RESULTS: In a 1-year study of 305 Chinese community-dwelling adults aged ≥18 years, urinary isoflavones, fecal microbiota, blood pressure, blood glucose and lipids, and anthropometric data were measured twice, 1 year apart. Brachial-ankle pulse wave velocity was also measured after 1 year. A linear mixed-effects model was used to analyze repeated measurements. Logistic regression was used to calculate the adjusted odds ratio (aOR) and 95% CI for the associations for arterial stiffness. Each 1 µg/g creatinine increase in urinary equol concentrations was associated with 1.47%, 0.96%, and 3.32% decrease in triglycerides, plasma atherogenic index, and metabolic syndrome score, respectively (all P<0.05), and 0.61% increase in high-density lipoprotein cholesterol (P=0.025). Urinary equol was also associated with lower risk of arterial stiffness (aOR, 0.28 [95% CI, 0.09-0.90]; Ptrend=0.036). We identified 21 bacterial genera whose relative abundance was positively associated with urinary equol (false discovery rate-corrected P<0.05) and constructed a microbial species score to reflect the overall equol-predicting capacity. This score (per 1-point increase) was inversely associated with triglycerides (percentage difference=-1.48%), plasma atherogenic index (percentage difference=-0.85%), and the risk of arterial stiffness (aOR, 0.27 [95% CI, 0.08-0.88]; all P<0.05). CONCLUSIONS: Our findings suggest that urinary equol and equol-predicting microbial species may improve cardiometabolic risk parameters in Chinese adults.

Lubricating Polymer Gels/Coatings: Syntheses and Measurement Strategies.

Straightforward design and long-term functionality for tribological considerations has prompted an extensive substitution of polymers for metals across various applications, from industrial machinery to medical devices. Lubrication of and by polymer gels/coatings, essential for ensuring the cost-effective operation and reliability of applications, has gained strong momentum by benefiting from the structural characteristics of natural lubrication systems (such as articular cartilage). The optimal synthetic strategy for lubricating polymer gels/coatings would be a holistic approach, wherein the lubrication mechanism in relation to the structural properties offers a pathway to design tailor-made materials. This review considers recent synthesis strategies for creating lubricating polymer gels/coatings from the molecular level (including polymer brushes, loops, microgels, and hydrogels), and assessing their frictional properties, as well as considering the underlying mechanism of their lubrication.

Micro-CT-assisted identification of the optimal time-window for antifibrotic treatment in a bleomycin mouse model of long-lasting pulmonary fibrosis.

Idiopathic Pulmonary Fibrosis (IPF) is a debilitating and fatal lung disease characterized by the excessive formation of scar tissue and decline of lung function. Despite extensive research, only two FDA-approved drugs exist for IPF, with limited efficacy and relevant side effects. Thus, there is an urgent need for new effective therapies, whose discovery strongly relies on IPF animal models. Despite some limitations, the Bleomycin (BLM)-induced lung fibrosis mouse model is widely used for antifibrotic drug discovery and for investigating disease pathogenesis. The initial acute inflammation triggered by BLM instillation and the spontaneous fibrosis resolution that occurs after 3 weeks are the major drawbacks of this system. In the present study, we applied micro-CT technology to a longer-lasting, triple BLM administration fibrosis mouse model to define the best time-window for Nintedanib (NINT) treatment. Two different treatment regimens were examined, with a daily NINT administration from day 7 to 28 (NINT 7-28), and from day 14 to 28 (NINT 14-28). For the first time, we automatically derived both morphological and functional readouts from longitudinal micro-CT. NINT 14-28 showed significant effects on morphological parameters after just 1 week of treatment, while no modulations of these biomarkers were observed during the preceding 7-14-days period, likely due to persistent inflammation. Micro-CT morphological data evaluated on day 28 were confirmed by lung histology and bronchoalveolar lavage fluid (BALF) cells; Once again, the NINT 7-21 regimen did not provide substantial benefits over the NINT 14-28. Interestingly, both NINT treatments failed to improve micro-CT-derived functional parameters. Altogether, our findings support the need for optimized protocols in preclinical studies to expedite the drug discovery process for antifibrotic agents. This study represents a significant advancement in pulmonary fibrosis animal modeling and antifibrotic treatment understanding, with the potential for improved translatability through the concurrent structural-functional analysis offered by longitudinal micro-CT.

An Intraoperative Method to Minimize Leg Length Discrepancy in Anterior Minimally Invasive Total Hip Arthroplasty-A Prospective Study.

While several intraoperative devices have been described in the literature for assessing leg length discrepancy (LLD), none have been utilized during total hip arthroplasty (THA) performed via the Anterior Minimally Invasive Surgery (AMIS) approach. The aim of this prospective study was to evaluate the efficacy and accuracy of a compass device in assessing leg length during THA performed using the AMIS technique. A prospective study was conducted involving 35 patients who consecutively underwent unilateral primary THA using the AMIS technique at our department from September 2017 to December 2018. LLD was measured by comparing preoperative and postoperative anteroposterior radiographs of the pelvis, independently assessed by two observers. The mean preoperative LLD was 3.6 (SD 3.9, range, 0.2-19.3) mm. The mean postoperative LLD was 2.5 (SD 3.0, range, 0-12.2) mm. A postoperative LLD of less than 5 mm was observed in 88.2% of cases, with 94.1% having values less than 10 mm. In conclusion, the compass device emerged as a valuable tool for ensuring precise limb length control in THA with the AMIS approach, offering both efficiency and cost-effectiveness in clinical practice.

Evaluating the Impact of Reminiscence Therapy on Cognitive and Emotional Outcomes in Dementia Patients.

This study examines the impact of reminiscence therapy on cognitive and emotional well-being in institutionalized older patients with dementia. Conducted at the Long-Term Care Health Facility for the Elderly, the research involved 34 participants who underwent therapy sessions that included personalized discussions of past experiences. Using physiological markers such as electroencephalography alpha and beta waves, along with psychological measures such as the Hasegawa Dementia Scale-Revised, the study aimed to quantify the effects of the therapy. Although the results indicated positive correlations between alpha and beta waves, suggesting enhanced relaxation and cognitive engagement, improvements in Hasegawa Dementia Scale-Revised scores were not statistically significant, pointing to variability in therapeutic effectiveness among patients. Despite these mixed outcomes, the findings support the potential of reminiscence therapy as a non-pharmacological intervention to improve the quality of life of dementia patients, though they also underscore the necessity for further research to refine therapy protocols and enhance applicability.

Facial morphology analysis of children with non-syndromic cleft lip and palate in a local population.

Objectives: To study the facial morphology in children with non-syndromic cleft lip and palate by applying numerical facial analysis on photographs for planning and evaluating treatment outcomes. Methods: This descriptive study was conducted from March 2020 to July 2020 in the Department of Oral Pathology, University of Health Sciences and Cleft Lip and Palate Hospital, Lahore Pakistan. A total of 104 patients of both genders with an age range from three months to thirteen years were included. Photographs of the participants were taken to measure facial anthropometrical landmarks including facial height, nose width, mouth width and inter canthal distance. The association between facial measurements with gender and phenotype and across age groups were computed keeping the confidence level at 95%. Results: Mean age of the children was 72.43±44.2 months with slight male predominance. Thirty-one percent presented with bilateral cleft lip and palate followed by unilateral cleft lip and plate. Total mean facial height, nose width and mouth width were found to be 143.46±21.52mm, 32.24±5.03mm and 33.71±4.38mm respectively. Intercanthal distance was measured to be 31.04±5.99mm. Statistically significant association was observed between gender and facial height, nose width, mouth width and Intercanthal distance. Conclusion: Facial anthropometric measures done on frontal photographs can be used to identify the facial landmarks in children with non-syndromic cleft lip and palate in low resource stings that may help surgeons in getting better aesthetic outcomes. These landmarks vary between ethnic groups therefore these should be specific to a particular race and ethnicity so as to ensure proper aesthetics and improved quality of life for the children of all nations.

Quantification of Methane Emissions from Cold Heavy Oil Production with Sand Extraction in Alberta and Saskatchewan, Canada.

Cold heavy oil production with sand (CHOPS) is an extraction process for heavy oil in Canada, with the potential to lead to higher CH4 venting than conventional oil sites, that have not been adequately characterized. In order to quantify CH4 emissions from CHOPS activities, a focused aerial measurement campaign was conducted in the Canadian provinces of Alberta and Saskatchewan in June 2018. Total CH4 emissions from each of 10 clusters of CHOPS wells (containing 22-167 well sites per cluster) were derived using a mass balance computation algorithm that uses in situ wind data measurement on board aircraft. Results show that there is no statistically significant difference in CH4 emissions from CHOPS wells between the two provinces. Cluster-aggregated emission factors (EF) were determined using correspondingly aggregated production volumes. The average CH4 EF was 70.4 ± 36.9 kg/m3 produced oil for the Alberta wells and 55.1 ± 13.7 kg/m3 produced oil for the Saskatchewan wells. Using these EF and heavy oil production volumes reported to provincial regulators, the annual CH4 emissions from CHOPS were estimated to be 121% larger than CHOPS emissions extracted from Canada's National Inventory Report (NIR) for Saskatchewan. The EF were found to be positively correlated with the percentage of nonpiped production volumes in each cluster, indicating higher emissions for nonpiped wells while suggesting an avenue for methane emission reductions. A comparison with recent measurements indicates relatively limited effectiveness of regulations for Saskatchewan compared to those in Alberta. The results of this study indicate the substantial contribution of CHOPS operations to the underreporting observed in the NIR and provide measurement-based EF that can be used to develop improved emissions inventories for this sector and mitigate CH4 emissions from CHOPS operations.

Facilitators and barriers in the implementation and adoption of Patient Reported Outcomes Measurements in daily practice.

OBJECTIVES: At the Erasmus MC, Patient Reported Outcome Measures (PROMs) are implemented on a hospital-wide scale. However, less than half of the patients and healthcare professionals (HCP) utilize these PROMs. Therefore, this study aimed to investigate facilitators and barriers for adoption of PROMs to develop guidance around implementation. METHODS: A mixed-methods study with a combination of interviews and focus groups, and questionnaires was conducted, involving patients, both PROM non-responders and PROM responders, HCPs, and medicine students and nurse specialists in training (hereafter 'students'). (Group)interview transcripts were subjected to thematic content analysis. Subsequently, questionnaires were developed and presented to all stakeholders to validate the findings. Last, identified themes and implementation recommendations were presented in a final questionnaire to the Value Based Healthcare Erasmus MC expert group to prioritize findings. RESULTS: Interviews were conducted with 15 patients, 14 HCPs and 4 students, and 2 focus groups with 5 students. The questionnaire was completed by 370/999 responders (37.0%), 173/1395 non-responders (12.5%), 44/194 HCPs (22.7%) and 40 students were reached via an open link. The identified facilitators and barriers were grouped into four overarching themes; training on PROMs at different levels in the education of (future) HCPS, motivate and reduce the burden for the HCP, implement generic and disease-specific PROMs simultaneously and motivate, activate and reduce the patient burden. CONCLUSIONS: Providing end-users with digital tools, implementation support and a clear hospital-wide vision are important, yet this does not guarantee successful adoption of PROMs. Successful adoption necessitates ongoing efforts to engage, motivate and train end-users.

A novel method to perform morphological measurements on three-dimensional (3D) models of the calcaneus based on computed tomography (CT)-imaging.

Background: While current preoperative and postoperative assessment of the fractured and surgically reconstructed calcaneus relies on computed tomography (CT)-imaging, there are no established methods to quantify calcaneus morphology on CT-images. This study aims to develop a semi-automated method for morphological measurements of the calcaneus on three-dimensional (3D) models derived from CT-imaging. Methods: Using CT data, 3D models were created from healthy, fractured, and surgically reconstructed calcanei. Böhler's angle (BA) and Critical angle of Gissane (CAG) were measured on conventional lateral radiographs and corresponding 3D CT reconstructions using a novel point-based method with semi-automatic landmark placement by three observers. Intraobserver and interobserver reliability scores were calculated using intra-class correlation coefficient (ICC). In addition, consensus among observers was calculated for a maximal allowable discrepancy of 5 and 10 degrees for both methods. Results: Imaging data from 119 feet were obtained (40 healthy, 39 fractured, 40 reconstructed). Semi-automated measurements on 3D models of BA and CAG showed excellent reliability (ICC: 0.87-1.00). The manual measurements on conventional radiographs had a poor-to-excellent reliability (ICC: 0.22-0.96). In addition, the percentage of consensus among observers was much higher for the 3D method when compared to conventional two-dimensional (2D) measurements. Conclusions: The proposed method enables reliable and reproducible quantification of calcaneus morphology in 3D models of healthy, fractured and reconstructed calcanei.

[Cardiac biomarkers prior to noncardiac surgery]. / Kardiale Biomarker vor nicht-kardiochirurgischen Eingriffen.

BACKGROUND: Cardiac biomarkers, such as high-sensitivity cardiac troponin (hs-cTn) and brain natriuretic peptide (BNP) or N­terminal prohormone of brain natriuretic peptide (NT-proBNP) are measured perioperatively to improve the prognosis and risk prediction. The European Society of Cardiology (ESC), European Society of Anesthesiology and Intensive Care (ESAIC) and the German Society of Anesthesiology and Intensive Care Medicine (DGAI) have recently published guidelines on the use of cardiac biomarkers prior to surgery. OBJECTIVE/RESEARCH QUESTION: This article provides an overview of the available evidence on perioperative troponin and BNP/NT-proBNP measurements. Current guideline recommendations are presented and discussed. MATERIAL AND METHODS: MEDLINE, Cochrane and google.scholar were searched for relevant keywords. Titles and abstracts of identified papers were checked for relevance and published results were summarized. Guideline recommendations from the ESC, ESAIC and DGAI are presented, compared and evaluated based on the available literature. In addition, the significance of new perioperative cardiac biomarkers is discussed based on the existing evidence. RESULTS: The definitions, diagnosis and management of cardiovascular events in the perioperative context differ from those in the nonsurgical setting. The evidence for the measurement of hs-cTn and BNP/NT-proBNP is evaluated differently in the guidelines and the resulting recommendations are partly contradictory. In particular, recommendations for changes in perioperative management based on biomarker measurements diverge. The ESC guidelines propose an algorithm that uses preoperative biomarkers as the basis for additional cardiac investigations. In particular, invasive coronary angiography is recommended for patients with stable chronic coronary syndrome who have no preoperative cardiac symptoms but elevated biomarkers. In contrast, the ESAIC guidelines emphasize that the available evidence is not sufficient to use perioperative biomarker measurements as a basis for a change in perioperative management. DISCUSSION: Treating physicians should coordinate interdisciplinary (surgery, anesthesiology, cardiology) recommendations for clinical practice based on the aforementioned guidelines. If cardiac biomarkers are routinely determined in high-risk patients, this should be done in accordance with the ESC algorithm.

Serial cardiac biomarkers, pulmonary artery pressures and traditional parameters of fluid status in relation to prognosis in patients with chronic heart failure: Design and rationale of the BioMEMS study.

AIMS: Heart failure (HF), a global pandemic affecting millions of individuals, calls for adequate predictive guidance for improved therapy. Congestion, a key factor in HF-related hospitalizations, further underscores the need for timely interventions. Proactive monitoring of intracardiac pressures, guided by pulmonary artery (PA) pressure, offers opportunities for efficient early-stage intervention, since haemodynamic congestion precedes clinical symptoms. METHODS: The BioMEMS study, a substudy of the MONITOR-HF trial, proposes a multifaceted approach integrating blood biobank data with traditional and novel HF parameters. Two additional blood samples from 340 active participants in the MONITOR-HF trial were collected at baseline, 3-, 6-, and 12-month visits and stored for the BioMEMS biobank. The main aims are to identify the relationship between temporal biomarker patterns and PA pressures derived from the CardioMEMS-HF system, and to identify the biomarker profile(s) associated with the risk of HF events and cardiovascular death. CONCLUSION: Since the prognostic value of single baseline measurements of biomarkers like N-terminal pro-B-type natriuretic peptide is limited, with the BioMEMS study we advocate a dynamic, serial approach to better capture HF progression. We will substantiate this by relating repeated biomarker measurements to PA pressures. This design rationale presents a comprehensive review on cardiac biomarkers in HF, and aims to contribute valuable insights into personalized HF therapy and patient risk assessment, advancing our ability to address the evolving nature of HF effectively.

Measurement and conceptualization of male involvement in family planning: a bibliometric analysis of Africa-based studies.

BACKGROUND: Male involvement in Family Planning (FP) is an exercise of men's sexual and reproductive health rights. However, the measurement of male involvement has been highly inconsistent and too discretional in FP studies. As a result, we used bibliometric tools to analyze the existing measures of male involvement in FP and recommend modifications for standard measures. METHODS: Using developed search terms, we searched for research articles ever published on male involvement in FP from Scopus, Web of Science, and PubMed databases. The search results were filtered for studies that focused on Africa. A total of 152 research articles were selected after the screening, and bibliometric analysis was performed in R. RESULTS: Results showed that 54% of the studies measured male involvement through approval for FP, while 46.7% measured it through the attitude of males to FP. About 31% measured male involvement through input in deciding FP method, while others measured it through inputs in the choice of FP service center (13.6%), attendance at FP clinic/service center (17.8%), and monetary provision for FP services/materials (12.4%). About 82.2% of the studies used primary data, though the majority (61.2%) obtained information on male involvement from women alone. Only about one in five studies (19.1%) got responses from males and females, with fewer focusing on males alone. CONCLUSION: Most studies have measured male involvement in FP through expressed or perceived approval for FP. However, these do not sufficiently capture male involvement and do not reflect women's autonomy. Other more encompassing measures of male involvement, which would reflect the amount of intimacy among heterosexual partners, depict the extent of the exercise of person-centered rights, and encourage the collection of union-specific data, are recommended.

Strategy for Ensuring the Metrological Traceability of Nanoparticle Size Measurements by SEM.

The concept of measurement traceability is crucial for ensuring the data reliability and the comparability of measurement results provided by different instruments and operators. In the field of nanoparticle metrology, determining the size of nanoparticles using electron microscopy-based techniques remains a real challenge. In laboratory settings, the establishment of traceability regarding the instrument calibration procedures, the assessment of uncertainties associated with instruments/operators/samples/environments, as well as the complexities related to electron-sample interactions, are often neglected. In this article, we describe the calibration procedure set up at the LNE (Laboratoire National de métrologie et d'Essais) and propose an evaluation method for determining the uncertainties in measuring nanoparticle size by SEM (Scanning Electron Microscopy). This study investigates the impact of the energy of the primary electrons (PEs) generated by the electron beam and accelerating voltage on the reliability of size measurements. The convolution between the signals coming from a nanoparticle and the substrate on which the particle is deposited induces edge effects that can have a negative impact on the measurement results. Finally, a diagram describing the various stages involved in establishing traceability for SEM measurements of nanoparticle size is proposed to facilitate the work of future operators.

Structural, Electrical, and Optical Properties of Single-Walled Carbon Nanotubes Synthesized through Floating Catalyst Chemical Vapor Deposition.

Single-walled carbon nanotube (SWCNT) thin films were synthesized by using a floating catalyst chemical vapor deposition (FCCVD) method with a low flow rate (200 sccm) of mixed gases (Ar and H2). SWCNT thin films with different thicknesses can be prepared by controlling the collection time of the SWCNTs on membrane filters. Transmission electron microscopy (TEM) showed that the SWCNTs formed bundles and that they had an average diameter of 1.46 nm. The Raman spectra of the SWCNT films suggested that the synthesized SWCNTs were very well crystallized. Although the electrical properties of SWCNTs have been widely studied so far, the Hall effect of SWCNTs has not been fully studied to explore the electrical characteristics of SWCNT thin films. In this research, Hall effect measurements have been performed to investigate the important electrical characteristics of SWCNTs, such as their carrier mobility, carrier density, Hall coefficient, conductivity, and sheet resistance. The samples with transmittance between 95 and 43% showed a high carrier density of 1021-1023 cm-3. The SWCNTs were also treated using Brønsted acids (HCl, HNO3, H2SO4) to enhance their electrical properties. After the acid treatments, the samples maintained their p-type nature. The carrier mobility and conductivity increased, and the sheet resistance decreased for all treated samples. The highest mobility of 1.5 cm2/Vs was obtained with the sulfuric acid treatment at 80 °C, while the highest conductivity (30,720 S/m) and lowest sheet resistance (43 ohm/square) were achieved with the nitric acid treatment at room temperature. Different functional groups were identified in our synthesized SWCNTs before and after the acid treatments using Fourier-Transform Infrared Spectroscopy (FTIR).

Electro-osmotic Flow Generation via a Sticky Ion Action.

Selective transport of ions through nanometer-sized pores is fundamental to cell biology and central to many technological processes such as water desalination and electrical energy storage. Conventional methods for generating ion selectivity include placement of fixed electrical charges at the inner surface of a nanopore through either point mutations in a protein pore or chemical treatment of a solid-state nanopore surface, with each nanopore type requiring a custom approach. Here, we describe a general method for transforming a nanoscale pore into a highly selective, anion-conducting channel capable of generating a giant electro-osmotic effect. Our molecular dynamics simulations and reverse potential measurements show that exposure of a biological nanopore to high concentrations of guanidinium chloride renders the nanopore surface positively charged due to transient binding of guanidinium cations to the protein surface. A comparison of four biological nanopores reveals the relationship between ion selectivity, nanopore shape, composition of the nanopore surface, and electro-osmotic flow. Guanidinium ions are also found to produce anion selectivity and a giant electro-osmotic flow in solid-state nanopores via the same mechanism. Our sticky-ion approach to generate electro-osmotic flow can have numerous applications in controlling molecular transport at the nanoscale and for detection, identification, and sequencing of individual proteins.

The Impact of Sustainability Courses: Are They Effective in Improving Diet Quality and Anthropometric Indices?

There are studies on the effect of general nutrition education on diet quality and anthropometric measurements, while studies showing the effectiveness of sustainable nutrition education, which also addresses the effect of food on the environment, are quite limited. This study aimed to investigate the effects of sustainable nutrition education on diet quality, anthropometric measurements, and the carbon footprint (CFP) and water footprint (WFP) of diet. A total of 160 university students received 1 h of sustainable nutrition education for 6 weeks. Before, at the end of, and 2 months after the courses, 24 h food consumption records were taken to assess diet quality and CFP and WFP values of diet, and Mediterranean diet (MedDiet) and Healthy Eating Index (HEI)-2020 scores were evaluated. The results of the study showed that sustainable nutrition education increased MedDiet score by 1.86 points and HEI-2020 score by 7.38 points. This education program also decreased body weight, body mass index (BMI), fat mass, and neck circumference. Sustainability education has a positive impact on calcium, potassium, and magnesium intakes, a negative impact on vitamin B12 and zinc intakes, and no effect on total protein intake. Education resulted in a 22% reduction in CFP and a 10% reduction in WFP.

Corrosion Inhibition Properties of Corrosion Inhibitors to under-Deposit Corrosion of X65 Steel in CO2 Corrosion Conditions.

Under-deposit corrosion is widely present in the pipelines of oil and gas production, causing significant corrosion damage. In this paper, a novel electrochemical cathodic-polarization method was carried out to accelerate the formation of CaCO3 scale on a X65 steel surface in a simulated solution containing scaling ions. Subsequently, pre-scaled X65 steel was placed in a high temperature and pressure autoclave to conduct corrosion weight-loss experiments and in situ electrochemical measurements. The study mainly compared the corrosion inhibition behavior of four quaternary ammonium salt corrosion inhibitors, pyridinium quaternary salt (BPC), quinolinium quaternary salt (BQC), 8-hydroxyquinolinium quaternary salt (BHQ) and pyridinium (1-chloromethyl naphthalene) quaternary salt (1-CPN), in a simulated oilfield scale under corrosive conditions. The results of the weight-loss experiments demonstrated that the inhibition efficiencies of the corrosion inhibitors from high to low were as follows: 1-CPN < BHQ < BQC < BPC. The in situ electrochemical measurements showed that the immersion time and type of corrosion inhibitor had a pronounced influence on the corrosion and corrosion inhibition behavior of X65 steel with CaCO3 coating. It was also proved using both EIS and PC that 1-CPN shows the best inhibition performance in all. Lastly, the inhibition mechanism of corrosion inhibitors at under-deposit conditions was analyzed via a surface morphology observation of SEM.

Measurements of Nuclear Magnetic Shielding in Molecules.

The origin of nuclear magnetic shielding in diamagnetic molecules is discussed, pointing out various contributions to the shielding from electrons and the effects of intra- and intermolecular interactions. In NMR practice, chemical shifts are determined first as the measure of shielding in observed samples. The descriptions of shielding and chemical shifts are not fully consistent. Gas phase studies permit the withdrawal of intermolecular contributions from shielding and obtaining the magnetic shielding data in isolated molecules. The shielding determination in molecules is possible using at least three methods delivering the reference shielding standards for selected nuclei. The known shielding of one magnetic nucleus can be transferred to other nuclei if the appropriate nuclear magnetic moments are available with satisfactory accuracy. It is possible to determine the nuclear magnetic dipole moments using the most advanced ab initio shielding calculations jointly with the NMR frequencies measurements for small-sized isolated molecules. Helium-3 gas is postulated as all the molecules' primary and universal reference standard of shielding. It can be easily applied using common deuterium lock solvents as the secondary reference standards. The measurements of absolute shielding are available for everyone with the use of standard NMR spectrometers.