bluuebunny/crossref_metadata_2025 huggingface dataset:
Access to personal protective equipment in exposed healthcare workers and COVID-19 illness, severity, symptoms and duration: a population-based case-control study in six countries
Authors: Kim Hyunju , Hegde Sheila , LaFiura Christine , Raghavan Madhunika , Sun Nancy , Cheng Susan , Rebholz Casey M , Seidelmann Sara B
Published: January 2021

Background

Despite the widespread implementation of personal protective equipment (PPE) in the COVID-19 pandemic, there are surprisingly few studies of its impact. To assess the risk, severity and duration of COVID-19 in relation to access to PPE in at-risk healthcare workers (HCWs).

Methods

From 17 July to 25 September 2020, at-risk physicians and nurses registered as a provider in the Survey Healthcare Globus network in six countries (the UK, Germany, France, Italy, Spain and USA) were identified based on adult medical specialties with frequent and close contact with patients with COVID-19. Exposed HCWs completed a detailed questionnaire including demographics, medical, social and lifestyle factors. COVID-19 cases were defined as COVID-19 symptoms (fever, cough, fatigue, loss of taste or smell) and asymptomatic COVID-19 test positive cases.

Results

Among 2884 exposed HCWs (94% medical doctors and 6% nurses or physician assistants), there were 514 reports of COVID-19 illness and 54 asymptomatic COVID-19 test positive cases. COVID-19 risk was significantly associated with close contact with COVID-19 cases both inside and outside the workplace, number of work shifts and hours worked per week. Limited access to PPE compared with access to a fresh mask, gown and gloves and face shield with each patient encounter was associated with a 2.2-fold to 22-fold increased risk of reporting COVID-19 symptoms (p<0.0001), a pattern consistent across all six countries. Further, limited access to PPE was associated with symptom duration greater than 2 weeks and the presence of moderate to severe symptoms such as difficulty breathing, abnormal chest X-ray, low oxygen saturations, respiratory distress and acute lung injury.

Conclusion

In six countries, less access to PPE was strongly associated with both increased risk of reporting COVID-19 illness as well as more prolonged and severe disease course in frontline HCWs.
How big is your bubble? Characteristics of self-isolating household units (‘bubbles’) during the COVID-19 Alert Level 4 period in New Zealand: a cross-sectional survey
Authors: Kearns Nethmi , Shortt Nick , Kearns Ciléin , Eathorne Allie , Holliday Mark , Mackle Diane , Martindale John , Semprini Alex , Weatherall Mark , Beasley Richard , Braithwaite Irene
Published: January 2021

Objective

To characterise the self-isolating household units (bubbles) during the COVID-19 Alert Level 4 lockdown in New Zealand.

Design, setting and participants

In this cross-sectional study, an online survey was distributed to a convenience sample via Facebook advertising and the Medical Research Institute of New Zealand’s social media platforms and mailing list. Respondents were able to share a link to the survey via their own social media platforms and by email. Results were collected over 6 days during Alert Level 4 from respondents living in New Zealand, aged 16 years and over.

Main outcomes measures

The primary outcome was the mean size of a self-isolating household unit or bubble. Secondary outcomes included the mean number of households in each bubble, the proportion of bubbles containing essential workers and/or vulnerable people, and the mean number of times the home was left each week.

Results

14 876 surveys were included in the analysis. The mean (SD) bubble size was 3.58 (4.63) people, with mean (SD) number of households 1.26 (0.77). The proportion of bubbles containing one or more essential workers, or one or more vulnerable persons was 45.3% and 42.1%, respectively. The mean number of times individual bubble members left their home in the previous week was 12.9 (12.4). Bubbles that contained at least one vulnerable individual had fewer outings over the previous week compared with bubbles that did not contain a vulnerable person. The bubble sizes were similar by respondent ethnicity.

Conclusion

In this New Zealand convenience sample, bubble sizes were small, mostly limited to one household, and a high proportion contained essential workers and/or vulnerable people. Understanding these characteristics from a country which achieved a low COVID-19 infection rate may help inform public health interventions during this and future pandemics.
Medication safety in primary care—from measurement to action
Authors: Bennie Marion , Kurdi Amanj , MacBride-Stewart Sean , Avery Tony
Published: January 2021

Topics for DTB review articles are selected by DTB’s editorial board to provide concise overviews of medicines and other treatments to help patients get the best care. Articles include a summary of key points and a brief overview for patients. Articles may also have a series of multiple choice CME questions.
Case of early-onset Alzheimer’s disease with atypical manifestation
Authors: Zhu Lin , Sun Limin , Sun Lin , Xiao Shifu
Published: January 2021

Short-term memory decline is the typical clinical manifestation of Alzheimer’s disease (AD). However, early-onset AD usually has atypical symptoms and may get misdiagnosed. In the present case study, we reported a patient who experienced symptoms of memory loss with progressive non-fluent aphasia accompanied by gradual social withdrawal. He did not meet the diagnostic criteria of AD based on the clinical manifestation and brain MRI. However, his cerebrospinal fluid examination showed a decreased level of beta-amyloid 42, and increased total tau and phosphorylated tau. Massive amyloid β-protein deposition by 11C-Pittsburgh positron emission tomography confirmed the diagnosis of frontal variant AD. This case indicated that early-onset AD may have progressive non-fluent aphasia as the core manifestation. The combination of individual and precision diagnosis would be beneficial for similar cases.
Atrial fibrillation prevalence, awareness and management in a nationwide survey of adults in China
Authors: Du Xin , Guo Lizhu , Xia Shijun , Du Jing , Anderson Craig , Arima Hisatomi , Huffman Mark , Yuan Yiqiang , Zheng Yang , Wu Shulin , Guang Xuefeng , Zhou Xianhui , Lin Hongbo , Cheng Xiaoshu , Dong Jianzeng , Ma Changsheng
Published: January 2021

Objective

To determine AF prevalence and gaps in atrial fibrillation (AF) awareness and management in China.

Methods

We conducted a community-based survey of 47 841 adults (age ≥45 years) in seven geographic regions of China between 2014 and 2016. Participants underwent a structured questionnaire, a standard 12-lead ECG, physical examination and blood sampling. AF prevalence, defined by either ECG detection or self-report, was estimated according to sampling weights, non-response and age and sex distribution of the population. We used multivariable logistic regression to estimate associations among sociodemographic, clinical and geographic factors with the AF prevalence, awareness and treatment.

Results

The weighted AF prevalence was 1.8% (95% CI 1.7% to 1.9%), but varied from 0.9% to 2.4% across geographical regions and equates to being present in an estimated 7.9 (95% CI 7.4 to 8.4) million people in China. Among men and women, the AF prevalence increased from 0.8% and 0.6% in the age group 45–54 years to 5.4% and 4.9% in the age group ≥75 years, respectively. Proportions of people who were aware of having AF decreased overall from 65.3% in 45–54 year-olds to 53.9% in ≥75 year-olds and varied between sex (men 58.5%, women 68.8%) and residency status (urban 78.3%, rural 35.3%). Only 6.0% of patients with high-risk AF received anticoagulation therapy.

Conclusions

AF prevalence is higher than previously reported in China, with low awareness and large treatment gaps. Large-scale efforts are urgently needed to reduce AF adverse consequences.
Levels of economic growth and cross-province spread of the COVID-19 in China
Authors: Mo Qiqing , Chen Xinguang , Yu Bin , Ma Zhenyu
Published: January 2021

Background

After the first COVID-19 case detected on 8 December 2019 in Wuhan, the Provincial Capital of Hubei, the epidemic quickly spread throughout the whole country of China. Low developmental levels are often associated with infectious disease epidemic, this study attempted to test this notion with COVID-19 data.

Methods

Data by province from 8 December 2019 to 16 February 2020 were analysed using regression method. Outcomes were days from the first COVID-19 case in the origin of Hubei Province to the date when case was first detected in a destination province, and cumulative number of confirmed cases. Provincial gross domestic products (GDPs) were used to predict the outcomes while considering spatial distance and population density.

Results

Of the total 70 548 COVID-19 cases in all 31 provinces, 58 182 (82.5%) were detected in Hubei and 12 366 (17.5%) in other destination provinces. Regression analysis of data from the 30 provinces indicated that GDP was negatively associated with days of virus spreading (β=−0.2950, p<0.10) and positively associated with cumulative cases (β=97.8709, p<0.01) after controlling for spatial distance. The relationships were reversed with β=0.1287 (p<0.01) for days and β=−54.3756 (p<0.01) for cumulative cases after weighing in population density and controlling for spatial distance.

Conclusion

Higher levels of developmental is a risk factor for cross-province spread of COVID-19. This study adds new data to literature regarding the role of economic growth in facilitating spatial spreading of infectious diseases, and provides timely data informing antiepidemic strategies and developmental plan to balance economic growth and people’s health.
Insurance-based inequities in emergency interhospital transfers: an argument for the prioritisation of patient care
Authors: Riegler Jacob
Published: January 2021

Currently there is an inequity in transfer rates of uninsured patients versus their insured counterparts. While this may vary by hospital system, studies indicate that this is a national trend, especially in emergency situations, and represents a prioritisation of profits over ethical obligations. This creates a variety of ethical issues for patients and society that generates a concordance between deontological and utilitarian viewpoints, two generally opposed schools of thought. The prioritisation of profit maximisation in order to provide better care for a select population is insufficient to justify deleterious health outcomes, stress and financial burden on patients. Current policy regarding patient transfers in the emergency department is insufficient to protect the uninsured and must be reevaluated.
‘The body says it’: the difficulty of measuring and communicating sensations of breathlessness
Authors: Malpass Alice , Mcguire Coreen , Macnaughton Jane
Published: January 2021

Breathlessness is a sensation affecting those living with chronic respiratory disease, obesity, heart disease and anxiety disorders. The Multidimensional Dyspnoea Profile is a respiratory questionnaire which attempts to measure the incommunicable different sensory qualities (and emotional responses) of breathlessness. Drawing on sensorial anthropology we take as our object of study the process of turning sensations into symptoms. We consider how shared cultural templates of ‘what counts as a symptom’ evolve, mediate and feed into the process of bodily sensations becoming a symptom. Our contribution to the field of sensorial anthropology, as an interdisciplinary collaboration between history, anthropology and the medical humanities, is to provide a critique of how biomedicine and cultures of clinical research have measured the multidimensional sensorial aspects of breathlessness. Using cognitive interviews of respiratory questionnaires with participants from the Breathe Easy groups in the UK, we give examples of how the wording used to describe sensations is often at odds with the language those living with breathlessness understand or use. They struggle to comprehend and map their bodily experience of sensations associated with breathlessness to the words on the respiratory questionnaire. We reflect on the alignment between cognitive interviewing as a method and anthropology as a disciplinary approach. We argue biomedicine brings with it a set of cultural assumptions about what it means to measure (and know) the sensorial breathless body in the context of the respiratory clinic (clinical research). We suggest the mismatch between the descriptions (and confusion) of those responding to the respiratory questionnaire items and those selecting the vocabularies in designing it may be symptomatic of a type of historical testimonial epistemic injustice, founded on the prioritisation of clinical expertise over expertise by experience.
Effect of ambient temperature on stroke onset: a time-series analysis between 2003 and 2014 in Shenzhen, China
Authors: Li Lei , Huang Suli , Duan Yanran , Liu Peiyi , Lei Lin , Tian Yuchen , Xiang Ming , Peng Ji , Cheng Jinquan , Yin Ping
Published: January 2021

Objective

Evidence on the relationship between ambient temperature and morbidity of different stroke subtypes in China is limited. This study aimed to assess the influence of ambient temperature on stroke risk in Shenzhen, China.

Methods

From 1 January 2003 to 31 December 2014, 114 552 stroke cases in Shenzhen were collected. A generalised additive model with quasi-Poisson regression combined with a distributed lag non-linear model was applied to evaluate the temperature effects on stroke subtypes. Furthermore, this study explored the variability of the effects across sex, age and education.

Results

The immediate heat effects on ischaemic stroke (IS) and the persistent effects of ambient temperature on intracerebral haemorrhage (ICH) were significant. Overall, the cold-related relative risks (RRs) of IS, ICH and subarachnoid haemorrhage (SAH) were 1.02 (0.97–1.07), 1.16 (1.04–1.30) and 1.12 (0.61–2.04), whereas the heat-related RRs were 1.00 (0.97–1.04), 0.80 (0.73–0.88) and 1.05 (0.63–1.78), respectively. For IS, a weakly beneficial cold effect was found among men while a detrimental heat effect among both men and women, the elderly and higher-educated population at lag0. However, regarding ICH, the temperature effects in men, the young and higher-educated population are stronger at lag0–4, lag0–7 as cold reveals threat and heat reveals protection.

Conclusion

Responses of diverse stroke subtypes to ambient temperature varied. Effective measures should be taken to increase public awareness about the effects of ambient temperature on stroke attack and to educate the public about self-protection.
Normal salivary gland ultrasonography could rule out the diagnosis of Sjögren’s syndrome in anti-SSA-negative patients with sicca syndrome
Authors: Al Tabaa Omar , Gouze Hélène , Hamroun Sabrina , Bergé Elisabeth , Belkhir Rakiba , Pavy Stephan , Jousse-Joulin Sandrine , Mariette Xavier
Published: January 2021

Objective

To evaluate the relevance of salivary gland ultrasound (SGUS) and its place in the diagnostic algorithm in patients referred with dry syndrome (DS) for a suspicion of Sjögren’s syndrome (SS).

Methods

We included all patients assessed at our dedicated DS clinic from June 2015 to September 2019 for which a SGUS has been carried out. Images were read blindly and the worst salivary gland was scored according to OMERACT classification. Clinical features, disease activity and treatments were collected.

Results

337 patients were seen from June 2015 to September 2019. 269 patients underwent SGUS. 77 patients were diagnosed with SS and 192 did not meet the ACR/EULAR criteria for SS: non-Sjögren’s DS (NSDS). Of these 192 patients, 60 had another possible cause of DS, and 132 patients were diagnosed with SAPS (sicca, asthenia, polyalgia syndrome).

SGUS abnormalities were significantly higher in patients with SS versus NSDS: 51% vs 8% for a score ≥2 (p<0.0001), and 43% vs 3% for a score ≥3 (p<0.0001). SGUS score ≥2 had a specificity (Sp) of 91%, sensitivity (Se) of 57%, positive predictive value (PPV) of 72% and negative predictive value (NPV) of 82% for SS diagnosis. SGUS’s characteristics in SSA-negative patients were similar to the whole population (Se=42%, Sp=91%, PPV=42%, NPV=92%). The high specificity and NPV in this population could avoid labial salivary gland biopsy (LSGB) in SSA-negative patients with normal SGUS (186 patients, 69%).

Conclusion

SGUS is useful for SS diagnosis. If anti-SSA antibodies are negative and SGUS score <2, the diagnosis of SS is very improbable and LSGB could be avoided.
Analysis of the $$ \varvec{e^+ e^- \rightarrow J/\psi D{\bar{D}}}$$ reaction close to the threshold concerning claims of a $$\chi _{c0}(2P)$$ state
Authors: Wang En , Liang Wei-Hong , Oset Eulogio
Published: January 2021

We analyze the $$D{\bar{D}}$$

D

D

¯

mass distribution from a recent Belle experiment on the $$e^+e^- \rightarrow J/\psi D{\bar{D}}$$

e
+

e
-

→
J
/
ψ
D

D

¯

reaction, and show that the mass distribution divided by phase space does not have a clear peak above the $$D{\bar{D}}$$

D

D

¯

threshold that justifies the experimental claim of a $$\chi _{c0}(2P)$$

χ

c
0

(
2
P
)

state from those data. Then we use a unitary formalism with coupled channels $$D^+D^-$$

D
+

D
-

, $$D^0{\bar{D}}^0$$

D
0

D

¯

0

, $$D_s{\bar{D}}_s$$

D
s

D

¯

s

, and $$\eta \eta $$

η
η

, with some of the interactions taken from a theoretical model, and use the data to fix other parameters. We then show that, given the poor quality of the data, we can get different fits leading to very different $$D{\bar{D}}$$

D

D

¯

amplitudes, some of them supporting a $$D{\bar{D}}$$

D

D

¯

bound state and others not. The main conclusion is that the claim for the $$\chi _{c0}(2P)$$

χ

c
0

(
2
P
)

state, already included in the PDG, is premature, but refined data can provide very valuable information on the $$D{\bar{D}}$$

D

D

¯

scattering amplitude. As side effects, we warn about the use of a Breit-Wigner amplitude parameterization close to threshold, and show that the $$D_s{\bar{D}}_s$$

D
s

D

¯

s

channel plays an important role in this reaction.
Optimal Time-Delay Control for Multi-Degree-of-Freedom Nonlinear Systems Excited by Harmonic and Wide-Band Noises
Authors: Hu Rongchun , Lü Qiangfeng
Published: January 2021

In this paper, an optimal time-delay control strategy is designed for multi-degree-of-freedom (multi-DOF) strongly nonlinear systems excited by harmonic and wide-band noises. First, by using the generalized harmonic functions, a stochastic averaging method (SAM) is employed for the time-delay controlled strongly nonlinear system under combined harmonic and wide-band noise excitations, by which a set of partially averaged Itô equations are obtained. Then, by solving the dynamical programming equation associated with the partially averaged Itô equations, the optimal control law can be obtained. Finally, by solving the Fokker–Planck–Kolmogorov (FPK) equation, the responses of the optimally time-delay controlled system are predicted. The analytical results are compared with the Monte Carlo simulation to verify the effectiveness and efficiency of the proposed control strategy.
A Multifractal Cross-Correlation Analysis of Economic Policy Uncertainty: Evidence from China and US
Authors: Zhao Ruwei , Dai Peng-Fei
Published: January 2021

In this study, we utilized the prevailing economic policy uncertainty index (EPU) as the proxy of state economic fluctuation and investigated Sino–US economic fluctuation long horizon cross-correlation with a multifractal detrended cross-correlation analysis (MF-DCCA). With the MF-DCCA approach, we found a reliable long-range cross-correlation between China and US EPU changes. In addition, we discovered that a power law cross-correlation existed for the variation of most scaling orders. However, no persistence of cross-correlations was detected within the Sino–US EPU change series. Additionally, we implemented Rényi exponent and spectrum singularity checks. Both the examination results proved series multifractality with the presented arch-shaped curves. We further calculated the Hölder exponent bounds within each series and found that the China EPU changes had maximal multifractality with the largest exponent difference.
Combinatorial Assortment Optimization
Authors: Immorlica Nicole , Lucier Brendan , Mao Jieming , Syrgkanis Vasilis , Tzamos Christos
Published: January 2021

Assortment optimization refers to the problem of designing a slate of products to offer potential customers, such as stocking the shelves in a convenience store. The price of each product is fixed in advance, and a probabilistic choice function describes which product a customer will choose from any given subset. We introduce the combinatorial assortment problem, where each customer may select a bundle of products. We consider a choice model in which each consumer selects a utility-maximizing bundle subject to a private valuation function, and study the complexity of the resulting optimization problem. Our main result is an exact algorithm for additive
k
-demand valuations, under a model of vertical differentiation in which customers agree on the relative value of each pair of items but differ in their absolute willingness to pay. For valuations that are vertically differentiated but not necessarily additive
k
-demand, we show how to obtain constant approximations under a “well-priced” condition, where each product’s price is sufficiently high. We further show that even for a single customer with known valuation, any sub-polynomial approximation to the problem requires exponentially many demand queries when the valuation function is XOS and that no FPTAS exists even when the valuation is succinctly representable.
A Theory of Robust API Knowledge
Authors: Thayer Kyle , Chasins Sarah E. , Ko Amy J.
Published: January 2021

Creating modern software inevitably requires using application programming interfaces (APIs). While software developers can sometimes use APIs by simply copying and pasting code examples, a lack of robust knowledge of how an API works can lead to defects, complicate software maintenance, and limit what someone can express with an API. Prior work has uncovered the many ways that API documentation fails to be helpful, though rarely describes precisely why. We present a theory of robust API knowledge that attempts to explain why, arguing that effective understanding and use of APIs depends on three components of knowledge: (1) the domain concepts the API models along with terminology, (2) the usage patterns of APIs along with rationale, and (3) facts about an API’s execution to support reasoning about its runtime behavior. We derive five hypotheses from this theory and present a study to test them. Our study investigated the effect of having access to these components of knowledge, finding that while learners requested these three components of knowledge when they were not available, whether the knowledge helped the learner use or understand the API depended on the tasks and likely the relevance and quality of the specific information provided. The theory and our evidence in support of its claims have implications for what content API documentation, tutorials, and instruction should contain and the importance of giving the right information at the right time, as well as what information API tools should compute, and even how APIs should be designed. Future work is necessary to both further test and refine the theory, as well as exploit its ideas for better instructional design.
Exploiting Spontaneous Transmissions for Broadcasting and Leader Election in Radio Networks
Authors: Czumaj Artur , Davies Peter
Published: January 2021

We study two fundamental communication primitives:
broadcasting
and
leader election
in the classical model of multi-hop radio networks with unknown topology and without collision detection mechanisms. It has been known for almost 20 years that in undirected networks with
n
nodes and diameter
D
, randomized broadcasting requires Ω(
D
log
n
/
D
+ log
2
n
) rounds, assuming that uninformed nodes are not allowed to communicate (until they are informed). Only very recently, Haeupler and Wajc (PODC'2016) showed that this bound can be improved for the model with spontaneous transmissions, providing an
O
(
D
log
n
log log
n
/log
D
+ log

O
(1)

n
)-time broadcasting algorithm. In this article, we give a new and faster algorithm that completes broadcasting in
O
(
D
log
n
/log
D
+ log

O
(1)

n
) time, succeeding with high probability. This yields the first optimal
O
(
D
)-time broadcasting algorithm whenever
n
is polynomial in
D
.

Furthermore, our approach can be applied to design a new leader election algorithm that matches the performance of our broadcasting algorithm. Previously, all fast randomized leader election algorithms have used broadcasting as a subroutine and their complexity has been asymptotically strictly larger than the complexity of broadcasting. In particular, the fastest previously known randomized leader election algorithm of Ghaffari and Haeupler (SODA'2013) requires
O
(
D
log
n
/
D
min {log log
n
, log
n
/
D
} + log

O
(1)

n
)-time, succeeding with high probability. Our new algorithm again requires
O
(
D
log
n
/log
D
+ log

O
(1)

n
) time, also succeeding with high probability.
Evaluation of a Laser Reduced Graphene Electrode Modified with Electrodeposited Silver Nanoparticles for SERS Detection
Authors: Aparicio-Martinez Eider , Estrada-Moreno Ivan A. , Dominguez Rocio B
Published: January 2021

The manufacturing of nanostructured surfaces for Surface Enhanced Raman Scattering (SERS) usually involves highly expensive techniques to achieve good performance. For this reason, this work proposes the preparation of a SERS substrate employing the electrochemical deposition of silver nanoparticles (AgNps) over a laser reduced graphene oxide electrode (LRGO). The material was obtained using laser irradiation of graphene oxide to restore the conductivity of the material and subsequently modified with silver nanoparticles. The material characterization corroborated the reduction of GO and the formation of AgNps with an average diameter of 103 nm. Finally, the LRGO-AgNps substrate was evaluated to detect the model analyte rhodamine 6G, achieving concentrations down to a 1x10-9 M. These results showed the developed material is suitable for application as a SERS substrate with the advantage of having been obtained through a low-cost and easy-to-implement method.
Study of Methanol Electro-Oxidation on Thin Nickel Films by Sampled Current Voltammetry
Authors: Salinas Maria Paula , Crespo-Yapur Diego Alfonso , Videa Marcelo
Published: January 2021

Nickel-based electrocatalysts have shown good catalytic activity for the electrochemical oxidation of alcohols in alkaline media, which has generated significant interest in using nickel films and nickel oxides in alcohol fuel cells. In this work, Ni films were deposited by the galvanostatic method on gold electrodes. The electrocatalytic activity for the electro-oxidation of methanol from these deposits was evaluated by cyclic voltammetry (CV) and sampled current voltammetry (SCV). Cyclic voltammetry measurements showed that depending on the Au electrode roughness, the position NiOOH formation peak of the electrodeposited Ni deposits could differ. The deposits were divided depending on whether the NiOOH formation peak was below or above 0.39 V vs. Ag|AgCl reference electrode. Sampled current voltammograms showed that the former presented greater specificity for the oxidation of methanol, and the latter, showed electrocatalytic activity for both the oxidation of methanol and for the oxygen evolution reaction.
Electrochemical Biosensor Development for Uric Acid Detection
Authors: Piedras Jessica Jetzabet , Dominguez Rocio B , Gutierrez Juan Manuel
Published: January 2021

Uric Acid (UA) is a purine metabolism final product in humans and is considered as an important biomarker for diseases like diabetes mellitus, metabolic syndrome, and gout. Thus, simple and cost-effective uric acid detection is highly desirable. This work focuses on developing an electrochemical biosensor for UA detection based on a screen-printed carbon electrode with immobilized uricase by a glutaraldehyde crosslinking procedure. The presence of immobilized uricase on the surface of the electrode was verified using cyclic voltammetry and the presence of a characteristic peak in the signal at a potential of –0.42 V. Biosensor response was analyzed with different UA concentrations in a range of 0 to 480 µM, the considered limit of detection was 6 µM. The obtained results suggest that the developed biosensor could be a promising alternative for simple and cost-effective UA detection on biological samples.
Study of Linear Sweep Voltammetry in Tequila and Raicilla Samples
Authors: Alvarez Alejandra , Carrillo Mercader A. , Gonzalez - Cruz MA , Carreon-Alvarez Clara , Moran-Lazaro Juan Pablo , Tostado-Plascencia M.M.
Published: January 2021

In this work, the study and comparison of the authentication of raicilla and tequila were investigated, using linear voltammetry, in which a copper electrode was used as a working electrode. It was found that for both alcoholic beverages the oxidation potentials are at a potential of -0.12 to -0.8 V and from -0.19 to -0.8 V (vs. Ag/AgCl) for tequila and raicilla correspondingly. The oxidation potentials found were explained in terms of the oxidation of the alcohols present in these beverages on the copper electrode, described in terms of the Fleischmann mechanism. On the other hand, the peak current in the tequila and the raicilla was analyzed according to the classification. In this sense, it was found that despite being of the same type of classification but of a different brand of tequila or raicilla, the peak current was different. This was explained in terms of the difference found during the production process and the agave used in each brand of tequila or raicilla.
Kinetic Study of the Cd-Biopolyelectrolyte Complexes Formation Using Square Wave Stripping Voltammetry
Authors: Oropeza Guzman Mercedes , Quintero-Gonzalez Carlos Alfonso , Romero Orellana Luis Alberto , Martinez-Quiroz Marisela , Lopez-Maldonado Eduardo Alberto
Published: January 2021

In this work an electrochemical methodology was developed to follow the association kinetics between a heavy metals and two different biopolymers, BP (corn gum and chitosan). This type of interaction is a key factor in the removal of metal ions contained in aqueous media at low concentrations. An aqueous solution with ppm of cadmium was used as a model to evaluate the kinetics of formation of the Cd-BP complex. The method selected for the quantification of cadmium was the square wave stripping voltammetry (SWSV). The experiment was carried out using a Britton-Robinson solution as a support electrolyte at pH 4.5, vitreous carbon as a working electrode, Calomel as a reference electrode, and graphite as a counter electrode. The initial concentration of Cd (II) solution was 10 mg/L. The concentration changes were recorded during 590 s. The kinetic models chosen to identify the reaction mechanism of the complex formation process were reversible first order and pseudo first order.
Emerging Contaminants Removed by Electro-Fenton Heterogeneous Using Porous Material of Chitosan and Magnetite Nanoparticles
Authors: Moreno-Medrano Edgar David
Published: January 2021

The present work shows the investigation of the synthesis of chitosan porous materials as support for magnetite nanoparticles for the degradation of drugs by means of electro-Fenton-type reactions in heterogeneous catalysis. These materials were successfully synthesized using a High Internal Phase Emulsion like a template, showing stability, very good porosity, and pore interconnectivity, which allowed the diffusion of the fluid inside. Furthermore, suitable conditions were found for the electro-generation of hydrogen peroxide and the degradation of the antibiotic ciprofloxacin.
Corrosion Analysis of Gasoline Level Sensor in E85 FUEL
Authors: Jáquez-Muñoz Jesús Manuel , Gaona Tiburcio Citlalli , Estupiñán López Francisco , Cabral Miramontes José Ángel , Orquiz Carlos , Marquez Clemente , Almeraya Calderon Facundo
Published: January 2021

For the time being biofuel is an important alternative to reduce the pollution caused by conventional based petroleum. One of the most common biofuels is the mix of bioethanol and gasoline in different percent. USA and EU use E22 and E85 (the number is the ethanol percent) as a fuel for diverse cars models. The main aim of this research was characterized the electrochemical behaviour of a gasoline level sensor that is made of metallic inks immerse in E85 fuel as an electrolyte, the sensor was divided in different zones. The electrochemical techniques employed were potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). Analysis by PP and EIS showed that in zone 1A (resistive ink) present a higher corrosion resistance, while when all zones and a connector are immersed in E85 the corrosion resistance decreases.
Corrosion Behavior of Titanium Alloys Using Electrochemical Noise
Authors: Jáquez-Muñoz Jesús Manuel , Gaona Tiburcio Citlalli , Cabral Miramontes José Ángel , Estupiñán López Francisco , Zambrano Robledo Patricia , Lara-Banda Maria , Almeraya Calderon Facundo
Published: January 2021

Nowadays aeronautic industry is looking for lighter materials as Ti alloys because they resist higher stress than aluminium alloys and are lighter than steel alloys, saving of this way volume and weight. The EN technique was used to evaluate the corrosión behaviour of different Ti-alloys in H2SO4 and NaCl at 3.5 wt% solutions. All samples presented mix corrosion being an indicative of the instability of passive layer generated in the electrolytes.
Corrosion Assessment of Fe-Ni-Al Based Alloy in Saline Solution
Authors: Espinosa-Medina Marco Antonio , Carbajal-De la Torre Georgina , Méndez Nancy Nelly Nelly
Published: January 2021

The corrosion assessment of a Fe-Al-Ni alloy in saline solution was carried out by using electrochemical techniques. The Fe-Al-Ni alloy was produced by casting in an induction furnace. It was microstructural and chemically characterized by SEM, EDS XRD. The microstructural characterization results of the casting Fe-Ni-Al alloy showed a homogeneous microstructure morphology, with some porosities formed during the solidification process. The Fe-Ni-Al base alloy presented a B2-(Fe,Ni)Al solid solution phase and non-third phase was observed. The potentiodynamic results showed a more positive Ecorr
value in the solution at pH 5. At the pH 7, the linear polarization resistance results showed the highest values of the icorr
kinetic. Whereas, the best performance against corrosion was observed at pH 5, where the lowest icorr
kinetic values were observed. This was associated to the formation of a more stable and dense scale of corrosion products at that condition.
Comparison of the Properties of Tin Selenide Thin Films Synthesized by Electrodeposition
Authors: Alvarez Alejandra , Vázquez-García Luis Fernando , Castañeda-Valderrama Rocío , Sánchez-Tizapa Marciano , Rodríguez-López José Luis , Huerta-Ávila Héctor
Published: January 2021

In this work we present a comparison of the properties of three tin selenide (SnSe) thin films synthesized by electrodeposition under air or nitrogen atmosphere. The films were synthesized at -0.7 V, -0.8 V, and -0.9 V vs. Ag/AgCl using a fluorine doped tin oxide conductive glass as working electrode, a silver chloride electrode as reference electrode, and a platinum mesh as counter electrode. After the electrodeposition, films were heated at 55°C for 30 minutes in air atmosphere. Films without and with thermal treatment were characterized by UV-Visible Spectroscopy, Atomic Force Microscopy, and Raman Spectroscopy. Analyzing the results, it was found that the optimal conditions for the electrodeposition were at -0.8 V vs Ag/AgCl. Band gap values were in the range from 1.2 to 1.5 eV. Raman spectroscopy revealed characteristic vibrational modes of SnSe and SnSe2 materials. The analysis by Atomic Force Microscopy revealed grain size of 100-700 nm.
Corrosion Mechanism of a X100 Pipeline Steel in NACE Brine at 1000 rpm
Authors: Campechano-Lira Clarisa , Bedolla A. , Contreras A. , Orozco Cruz Ricardo , Galván Martínez R.
Published: January 2021

This work shows the research about the corrosion mechanism analysis of a X100 pipeline steel immersed in NACE brine under turbulent flow conditions (1000 and 5000 rpm) at room temperature and atmospheric pressure of Veracruz Port. In order to study the hydrodynamic conditions, a rotating cylinder electrode (RCE) was used, while to the electrochemical analysis, the electrochemical techniques like potentiodynamic Polarization Curves (PC) and Linear Polarization Resistance (RPL) were used. The obtained results shown that the corrosion system is limited by the mass transfer process, specifically the oxygen transfer from the bulk to the metallic surface, due to the momentum transfer, called “Convective Diffusion.” It is important to point out that this diffusion can modify the electrochemical reactions (incrementing of redox reactions), so the stability of the corrosion products films adsorbed on metallic surface are dependent to the shear stress and the aggressiveness of the medium.
Studies of Corrosion Resistant Properties of PU Coatings Reinforced with La-Pr-O Nanostructures
Authors: Rocha-Ortíz E. , Brachetti-Sibaja S. B. , Palma-Ramírez D. , Torres-Huerta A.M. , Dorantes-Rosales H. J. , Rodríguez-Salazar A. E. , Domínguez-Crespo M. A.
Published: January 2021

This work examines the main parameters to obtain solid solutions of La-Pr-O nanostructures and their incorporation into a poly(urethane) (PU) based on hexamethylene diisocyanate (HDI) (PU-HDI). The effect of obtaining La-Pr-O at different intervals of time was evaluated. Structural results indicated that the alloys, as solid solutions, can be obtained during the first 60 min. These nanostructures were found to have morphologies of agglomerates growing from random and irregular shapes of particles. Once stablished the optimal conditions, 1, 3, and 5 wt.% of La-Pr-O nanostructures were incorporated into PU-HDI through magnetic stirring and deposited onto AISI 1060 carbon steel by spray technique. XRD indicated that the nanostructures were successfully dispersed into PU-HDI with a final reduced crystal size related to the adequate dispersion. The electrochemical findings, such as the displacement in the Ecorr
towards to positive direction, an important reduction of the jcorr
and polarization resistance, demonstrate that La-Pr-O nanostructures offer an effective strategy to improve barrier properties of PU systems.
Electrochemical Performance of UHMWPE Biocompatible Coatings on Ti6Al4V Alloy in Simulated Body Solutions: Influence of Immersion Time
Authors: Anaya-Garza Karely , Domínguez-Crespo Miguel A. , Torres-Huerta A.M. , Palma-Ramírez D. , Rodríguez-Salazar A. E. , Ramírez-Meneses E. , Brachetti-Sibaja B.
Published: January 2021

Ti6Al4V alloys are widely employed in the production of orthopedic implants due to their adequate mechanical properties, corrosion resistance, and biocompatibility. Nevertheless, these alloys present a high friction coefficient and low wear resistance limiting their half-life time. Then, once implanted, the interaction between the metal and the surrounding tissue can promote the corrosion process which in turn can ultimately trigger its rejection. In this work, ultra-high molecular weight polyethylene (UHMWPE) films were coated onto Ti6Al4V alloy substrates using the dip coating method to evaluate the influence of immersion time on the electrochemical performance in Simulated Body Solutions. The coating thickness was ranged from 11-20 µm changing the immersion time between 20 and 40 s. Structural characterization shows that an increase in the immersion time reduces the crystallinity of UHMWPE coatings and their porosity from 32 to 0.2%. The performance of the films as protective barriers against the corrosion process was enhanced with high immersion times, decreasing the corrosion rate up to 0.05 µm y-1 (40 s).
Electrochemical Evaluation of Acanthocereus Tetragonus Extract Corrosion Inhibitor for Aluminum in NaCl (0.6 M) and HCl (1 M)
Authors: Méndez Figueroa Henevith Gisell , Galvan-Martinez Ricardo , López-López Ari Yamir , Ramirez-Fernandez Jose Arturo , Orozco Cruz Ricardo
Published: January 2021

In this work, Acanthocereus tetragonus extract from stems ripe was used as corrosion inhibitor for aluminum in NaCl (0.6 M) and HCl (1 M). The extract was added in 50 ppm, 100 ppm, and 200 ppm and evaluated at 0 h, 6 h, 12 h, and 24 h with Linear Polarization Resistance (LPR), Electrochemical Impedance Spectroscopy (EIS), and Polarization Curves (PC). As results, the efficiency shows an increase with longer exposure time. Moreover, the efficiencies reached 76% in NaCl (0.6 M) and 52% in HCl (1 M), with 50 ppm after 24 h in both electrolytes.
Electrochemical Evaluation of Three Zinc-Rich Paints on Carbon Steel Substrates Exposed to 3.5% NaCl
Authors: Ataxca Corintia Guadalupe , Martinez Daniel , Galicia Aguilar Gonzalo , Chavez-Rosales Rosario , Orozco Cruz Ricardo
Published: January 2021

Coatings are the most common method of corrosion control based on isolating a metal from the aggressive environment. They also represent one of the most effective tools to combat the degradation of metallic materials. This research work evaluates using electrochemical techniques, three paint systems rich in zinc: Zerovoc (Z1), ZRC Galvilite (Z2), and Zinga (Z3), on carbon steel substrates. As a first step, the different coatings were applied. Subsequently, the characterization was carried out using direct current (DC) and alternating current (AC) electrochemical techniques; Linear Polarization Resistance (LPR) and Electrochemical Impedance Spectroscopy (EIS). The systems were evaluated in a period of 30 days of immersion in 3.5% NaCl obtaining as a result a degradation mechanism and the corrosion rate for each paint. Based on the results, it was determined that the ZRC Galvilite (Z2) system represented the best protection performance.
Electrochemical Evaluation of Galvanized Steel
Authors: Lugo Gabriela , Gallardo Castán Ernesto , Lagunes Acosta Arturo , Chavez Rosales Rosario , Garcia Navarro Norma , Ramírez Reyes José Luis , Galicia Aguilar Gonzalo , Galicia Badillo Aurora Edelmira
Published: January 2021

In this work, the corrosive behavior of commercial galvanized steel samples with and without defects on their surface is evaluated in aqueous media to simulate the marine environment with the presence of chlorides and sulfates, a common environment for steel parts for industrial purposes. Galvanized steel samples were exposed in two electrolytes (3% sodium chloride and 0.1 M sodium sulfate) in a period of 40 days. Then the samples were subjected to electrochemical tests (Polarization Resistance, Electrochemical Impedance Spectroscopy, and Potentiodynamic Polarization Curves) to predict the behavior in terms of their deterioration or destruction of the material. It was found that the defective and non-defective samples immersed in the sodium chloride electrolyte presented greater deterioration due to corrosion since the substance causes greater destructive effects in metallic materials compared to sodium sulfate.
Experimental Study of the Evolution of Acid Fronts During Galvanic Corrosion of the CS/AA6063 and CS/AA7075 Systems
Authors: Ortiz Alma , Ruíz-García A. , Genesca Juan , Montoya Rodrigo
Published: January 2021

This work proposes an experimental arrangement to determine the propagation of pH fronts during the galvanic corrosion process of different aluminum alloys in contact with carbon steel and under gelled-electrolytes. Both thick and thin electrolyte thickness were tested as well as concentrated and dilute electrolytes. The results show that the propagation of acidic fronts is faster under dilute electrolytes. Under thin electrolytes the evolution of the acid front is confined around the metallic joint of the system (always on top of the aluminum alloy). Such a behavior is not observed when the galvanic couple is under thick electrolytes.
Analysis of the Transport Number of Cadmium and Lead from an Extract of Soils Contaminated with Mining Seals through a Commercial Membrane
Authors: Vazquez Rodriguez Guadalupe , Baltazar Vera Juan Carlos , Alvarado Montalvo Lucia Guadalupe , Tirado Torres David , Delgadillo Ruiz Eladio , Ramirez Ramirez Natividad , Calderon Vega Felicitas , Torres Rodriguez Luz Maria , Montes Rojas Antonio
Published: January 2021

The historical contamination of soils by heavy metals shows little degradation and therefore they are considered as persistent bioaccumulative toxins, which represent a marked risk to human health ecosystems. In recent years, technologies have been developed to help alleviate the problem of contaminated soils. The methods developed have mainly focused on in situ remediation, among which electro remediation stands out for both organic and inorganic pollutants. The present work aims to analyze variables for the treatment of soils with heavy metals using electrochemical strategies with the application of commercial membranes. The analysis made it possible to determine the transition zone where the depletion of the counterion occurs in the diffusion layer of the cadmium and lead ion. The results of the limit current analysis in the membrane reflect the presence of a mixture of ions where the diffusion layer is altered by the mixture of ions present. The results suggest that the membrane presents fouling of complexing organic compounds in the diffusion layer and therefore behaves like a reactive membrane where the permeation channels and the fixed charge change their original function.
Electrochemical Study of the Localized Electrodeposition of Co Onto a Polycrystalline Gold Substrate
Authors: Corona Jair Azael , Mendoza Huizar L. Humberto , Álvarez Romero Giaan Arturo , Rivera Hernández Margarita , Saucedo Solorio José Manuel
Published: January 2021

Cobalt is a metal widely used in the computer industry because is a fundamental component. This has motivated an important research activity about the synthesis of Co particles at the nano and micro level. Microelectrodes (MEs) have been employed to analyze the Co electrodeposition process because their small dimensions allow the formation and growth of a minimum number of nuclei. In the present work, we employ a Co-ME as source of cobalt ions in order to electrodeposit cobalt onto a polycrystalline gold electrode. We placed a Co-ME on a specific position over the gold electrode surface. Then a dissolution potential pulse to the Co-ME was applied. At the same time, a deposition potential pulse to the gold electrode. Thus, it was possible to electrodeposit cobalt particles onto the gold electrode in a specific position.
Study of the Electrodeposition of Silver Nanoparticles on Glassy Carbon by Galvanostatic Control
Authors: Moreno Hernandez Roberto , Crespo-Yapur Diego Alfonso , Videa Marcelo
Published: January 2021

In this work, nucleation and growth processes under galvanostatic control are studied, taking silver as a reference system. The methodology proposed allows electrodeposition to be carried out in areas of 5 mm2 and with a reagent volume of 10 μL, using a capillary droplet cell built for this purpose. Silver nuclei were generated by transfer of the same charge but varying the intensity of the applied current density and the pulse duration. It was found that pulses with a current density of 1.70 mA/cm2 generate a high density of particles with low variability. The comparison between the galvanostatic and potentiostatic methods shows that the galvanostatic control generates smaller particles with high density. In contrast, the potentiostatic pulse result in a better spatial distribution of the particles on the electrode area limited by the droplet.