Association of pre-hospital tracheal intubation with outcomes after out-of-hospital cardiac arrest by drowning comparing to supraglottic airway device: A nationwide propensity score-matched cohort study

AIM OF THE STUDY

This study aimed to compare the survival outcomes of adult patients with out-of-hospital cardiac arrest (OHCA) by drowning who were treated with either endotracheal intubation (ETI) or a supraglottic airway (SGA) device.

METHODS

We compared the outcomes of patients with OHCA by drowning according to airway management using a Japanese nationwide population-based registry (All-Japan Utstein Registry). Adult patients with OHCA treated in 2014-2020 with advanced airway management (ETI or SGA) were included. Patients who received ETI during cardiopulmonary resuscitation were matched with those treated with SGA based on propensity scores in a 1:1 ratio with a 0.2 calliper width. The outcome measures were the return of spontaneous circulation (ROSC), survival at one month, and favourable neurological outcomes defined as a Cerebral Performance Category Scale score of 1 or 2.

RESULTS

Of the 11,703 eligible patients, 4,467 (38.2%) and 7,236 (61.8%) underwent ETI and SGA, respectively. A total of 3,566 patients in each cohort were matched. The ROSC rate was higher in those treated with ETI versus SGA (207/3,566 [5.8%] versus 167/3,566 [4.7%], respectively; adjusted odds ratio, 1.25; 95% confidence interval [CI], 1.02-1.55). There was no intergroup difference in one-month survival or favourable neurological outcome (32/3566 [0.90%] versus 34/3566 [0.95%]; odds ratio, 0.94; 95% CI, 0.58-1.53; and 9/3566 [0.25%] versus 8/3566 [0.22%]; odds ratio, 1.13; 95% CI, 0.43-2.92), respectively.

CONCLUSIONS

In this propensity score-matched study of adult OHCA by drowning, ETI compared to SGA was associated with ROSC but not associated with survival and favourable neurological outcomes at one month.

Association between the severity of hypothermia and in-hospital mortality in patients with infectious diseases: The J-Point registry

Aim

Hypothermia is associated with poor prognosis in patients with sepsis. However, no studies have explored the correlation between the severity of hypothermia and prognosis.

Methods

Using data from the Japanese accidental hypothermia network registry (J-Point registry), we examined adult patients aged ≥18 years with infectious diseases whose initial body temperature was ≤35°C from April 1, 2011 to March 31, 2016, in 12 centers. Patients were divided into three groups according to their body temperature: Tertile 1 (T1) (32.0-35.0°C), Tertile 2 (T2) (28.0-31.9°C), and Tertile 3 (T3) (<28.0°C). In-hospital mortality was employed as a metric to assess outcomes. We conducted a multivariate logistic regression analysis to investigate the relationship between the three categories and the occurrence of in-hospital mortality.

Results

A total of 572 patients were registered, and 170 eligible patients were identified. Of these patients, 55 were in T1 (32.0-35.0°C), 76 in T2 (28.0-31.9°C), and 39 in T3 (<28.0°C) groups. The overall in-hospital mortality rate in accidental hypothermia (AH) patients with infectious diseases was 34.1%. The in-hospital mortality rates in the T1, T2, and T3 groups were 34.5%, 36.8%, and 28.2%, respectively. The multivariable analysis demonstrated no significant differences regarding in-hospital mortality among the three groups (T2 vs. T1, adjusted odds ratio [OR]: 1.29; 95% confidence interval [CI]: 0.58-2.89 and T3 vs. T1, adjusted OR: 0.83; 95% CI: 0.30-2.31).

Conclusion

In this multicenter retrospective observational study, hypothermia severity was not associated with in-hospital mortality in AH patients with infectious diseases.

Awake Fiberoptic Tracheal Intubation in a Patient With Traumatic Retropharyngeal Hematoma

Retropharyngeal hematoma is a rare disease triggered by neck trauma and can result in airway obstruction, requiring early recognition and consideration of tracheal intubation. We present a case of a 42-year-old woman brought to the emergency department with dyspnea after a traffic trauma, and a mild stridor was heard on cervical auscultation, indicating airway compromise. Contrast-enhanced computed tomography (CT) scan showed retropharyngeal hematoma. Considering her obesity and short neck, we performed awake fiberoptic intubation successfully without any complications. Awake fiberoptic intubation, directly confirming anatomic abnormalities, may increase the success rate of intubation and prevent complications, especially in patients at high risk for cannot intubate, cannot ventilate (CICV). Cervical auscultation may contribute to early diagnosis and treatment for airway obstruction in patients with cervical trauma. We report a case of awake fiberoptic tracheal intubation for a retropharyngeal hematoma in a patient at high risk for CICV and cervical auscultation in a primary survey.

Morel-Lavallée Lesion in a Female Breast: A Case Report

Morel-Lavalée lesions (MLLs) are caused by closed degloving injuries that mostly occur in the thigh, flank, and buttocks. We report a rare case of an MLL in the breast that was successfully treated with surgical removal in the acute phase. A 57-year-old woman sustained a breast injury from a seatbelt in a motor vehicle accident. Contrast-enhanced CT was performed, and the patient was diagnosed with an MLL in her breast. Surgical removal was performed after five days, and the patient was discharged six days postoperatively. No recurrence was observed, and the cosmetic results were good at six months postoperatively. Early detection and treatment of MLL in the female breast are critical to avoid recurrence and ensure good cosmetic outcomes.

Inactivation and spike protein denaturation of novel coronavirus variants by CuxO/TiO2 nano-photocatalysts

In order to reduce infection risk of novel coronavirus (SARS-CoV-2), we developed nano-photocatalysts with nanoscale rutile TiO₂ (4-8 nm) and Cu_xO (1-2 nm or less). Their extraordinarily small size leads to high dispersity and good optical transparency, besides large active surface area. Those photocatalysts can be applied to white and translucent latex paints. Although Cu₂O clusters involved in the paint coating undergo gradual aerobic oxidation in the dark, the oxidized clusters are re-reduced under > 380 nm light. The paint coating inactivated the original and alpha variant of novel coronavirus under irradiation with fluorescent light for 3 h. The photocatalysts greatly suppressed binding ability of the receptor binding domain (RBD) of coronavirus (the original, alpha and delta variants) spike protein to the receptor of human cells. The coating also exhibited antivirus effects on influenza A virus, feline calicivirus, bacteriophage Qβ and bacteriophage M13. The photocatalysts would be applied to practical coatings and lower the risk of coronavirus infection via solid surfaces.

Elsberg syndrome caused by herpes zoster in the sacral region with preceding urinary retention

Background

Elsberg syndrome (ES) is an acute-onset lumbosacral radiculitis with myelitis caused by a herpes virus infection.

Case Presentation

We present a case of a 77-year-old woman who was admitted with urinary retention prior to genital rash. The patient was diagnosed with ES and treated with intravenous acyclovir 250 mg every 8 h for 1 week.

Conclusion

Physicians should consider ES in patients with voiding dysfunction, as preceding neurological symptoms may lead to a misdiagnosis. Considering the adverse effects of the antiviral drug, its dosage should be according to the causative virus of the ES as well as the patient's age and medical history.

Development of a high-throughput method to screen novel antiviral materials

Respiratory infectious diseases pose a serious threat worldwide, and novel antiviral materials are highly demanded. Photocatalytic nanoparticles have been developed to inhibit indirect transmission of pathogens by acting as surface coating materials. During development of such antiviral materials, researchers use bacteriophages as model viruses due to their safety and experimental efficiency. Screening methods are used to identify potential antiviral materials, and better screening technologies will accelerate the discovery of antiviral treatments. In this study, we constructed a novel platform to evaluate antiviral activity of surface coating materials using the M13 bacteriophage and phagemid system derived from phage display technology. The evaluation results generated by this system for the two tested antiviral materials were comparable to those for the materials tested on the Qβ bacteriophage and influenza virus using traditional screening methods. The experimental system developed in this study provides rapid and effective screening and can be applied to the development of novel antiviral materials.

Clinical relevance of impaired consciousness in accidental hypothermia: a Japanese multicenter retrospective study

Aim

This study aimed to investigate the association between level of impaired consciousness and severe hypothermia (<28°C) and to evaluate the association between level of impaired consciousness and inhospital mortality among accidental hypothermia patients.

Methods

This was a multicenter retrospective study using the J‐Point registry database, which includes data regarding patients whose core body temperature was 35.0°C or less and who were treated as accidental hypothermia in emergency departments between April 1, 2011 and March 31, 2016. We estimated adjusted odds ratios of the level of impaired consciousness for severe hypothermia less than 28°C and inhospital mortality using a logistic regression model.

Results

The study included 505 of 572 patients in the J‐Point registry. Relative to mildly impaired consciousness (Glasgow Coma Scale [GCS] 13–15), the adjusted odds ratios for severe hypothermia less than 28°C were: moderate (GCS 9–12), 3.26 (95% confidence interval [CI], 1.69–6.25); and severe (GCS < 9), 4.68 (95% CI, 2.40–9.14). Relative to mildly impaired consciousness (GCS 13–15), the adjusted odds ratios for inhospital mortality were: moderate (GCS9–12), 1.65 (95% CI, 0.95–2.88); and severe (GCS < 9), 2.10 (95% CI, 1.17–3.78).

Conclusion

The level of impaired consciousness in patients with accidental hypothermia was associated with severe hypothermia and inhospital mortality.

Machine learning-based prediction models for accidental hypothermia patients

Background

Accidental hypothermia is a critical condition with high risks of fatal arrhythmia, multiple organ failure, and mortality; however, there is no established model to predict the mortality. The present study aimed to develop and validate machine learning-based models for predicting in-hospital mortality using easily available data at hospital admission among the patients with accidental hypothermia.

Method

This study was secondary analysis of multi-center retrospective cohort study (J-point registry) including patients with accidental hypothermia. Adult patients with body temperature 35.0 °C or less at emergency department were included. Prediction models for in-hospital mortality using machine learning (lasso, random forest, and gradient boosting tree) were made in development cohort from six hospitals, and the predictive performance were assessed in validation cohort from other six hospitals. As a reference, we compared the SOFA score and 5A score.

Results

We included total 532 patients in the development cohort [N = 288, six hospitals, in-hospital mortality: 22.0% (64/288)], and the validation cohort [N = 244, six hospitals, in-hospital mortality 27.0% (66/244)]. The C-statistics [95% CI] of the models in validation cohorts were as follows: lasso 0.784 [0.717–0.851] , random forest 0.794[0.735–0.853], gradient boosting tree 0.780 [0.714–0.847], SOFA 0.787 [0.722–0.851], and 5A score 0.750[0.681–0.820]. The calibration plot showed that these models were well calibrated to observed in-hospital mortality. Decision curve analysis indicated that these models obtained clinical net-benefit.

Conclusion

This multi-center retrospective cohort study indicated that machine learning-based prediction models could accurately predict in-hospital mortality in validation cohort among the accidental hypothermia patients. These models might be able to support physicians and patient’s decision-making. However, the applicability to clinical settings, and the actual clinical utility is still unclear; thus, further prospective study is warranted to evaluate the clinical usefulness.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40560-021-00525-z.

Care at critical care medical centers is associated with improved outcomes in patients with accidental hypothermia: a historical cohort study from the J-Point registry

Aim

The recommendation that patients with accidental hypothermia should be transported to specialized centers that can provide extracorporeal life support has not been validated, and the efficacy remains unclear.

Methods

This was a multicenter retrospective cohort study of patients with a body temperature of ≤35°C presenting at the emergency department of 12 hospitals in Japan between April 2011 and March 2016. We divided the patients into two groups based on the point of care delivery: critical care medical center (CCMC) or non‐CCMC. The primary outcome of this study was in‐hospital death. In‐hospital death was compared using a multivariable logistic regression analysis. Subgroup analyses were carried out according to patients with severe hypothermia (<28°C) or systolic blood pressure (sBP) of <90 mmHg.

Results

A total of 537 patients were included, 413 patients (76.9%) in the CCMC group and 124 patients (23.1%) in the non‐CCMC group. The in‐hospital death rate was lower in the CCMC group than in the non‐CCMC group (22.3% versus 31.5%, P < 0.001). The multivariable logistic regression analysis showed that the adjusted odds ratio (AOR) of the CCMC group was 0.54 (95% confidence interval, 0.32–0.90). In subgroup analyses, patients with systolic blood pressure <90 mmHg in the CCMC group were less likely to experience in‐hospital death (AOR 0.36; 95% CI, 0.23–0.56). However, no such association was observed among patients with severe hypothermia (AOR 1.08; 95% CI, 0.63–1.85).

Conclusions

Our multicenter study indicated that care at a CCMC was associated with improved outcomes in patients with accidental hypothermia.

Osborn Wave Is Related to Ventricular Fibrillation and Tachycardia in Hypothermic Patients

BACKGROUND

The Osborn wave (OW) is often observed in hypothermic patients; however, whether OW in hypothermic patients is related to the development of fatal ventricular arrhythmia, including ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT), remains undetermined. This study aimed to estimate the association between OW and the incidence of fatal ventricular arrhythmias.Methods and Results: This retrospective study used the Japanese Accidental Hypothermia Network registry database and included 572 hypothermic patients. Patients were divided into the OW group (those with OW) and non-OW group (those without OW). The relationship between the development of fatal arrhythmias and presence of OW was assessed using the chi-squared test. All patients who developed VF/VT (n=10) had OW on electrocardiogram upon hospital arrival. The presence of OW had a sensitivity of 100%, specificity of 47.8%, positive predictive value of 4.0%, and negative predictive value of 100% for VF/VT development. The in-hospital mortality rate was 22.3% in the OW group and 21.2% in the non-OW group (P=0.781).

CONCLUSIONS

OW was observed in all hypothermic patients with VF/VT. The occurrence of ventricular arrhythmias is highly unlikely in the absence of OW on the electrocardiogram. Although the presence of OW might be used to predict these fatal arrhythmias in hypothermic patients, there was no association between the presence of OW and in-hospital mortality.

Prognostic ability of the sequential organ failure assessment score in accidental hypothermia: a multi-institutional retrospective cohort study

Background

Severe accidental hypothermia (AH) is life threatening. Thus, prognostic prediction in AH is essential to rapidly initiate intensive care. Several studies on prognostic factors for AH are known, but none have been established. We clarified the prognostic ability of the Sequential Organ Failure Assessment (SOFA) score in comparison with previously reported prognostic factors among patients with AH.

Methods

The J-point registry database is a multi-institutional retrospective cohort study for AH in 12 Japanese emergency departments. From this registry, we enrolled patients who were treated at the intensive care unit (ICU) in various critical care medical centers. In-hospital mortality was the primary outcome. We investigated the discrimination ability of each candidate prognostic factor and the in-hospital mortality by applying the logistic regression models with areas under the receiver operating characteristic curve (AUROC) with 95% confidence interval (CI).

Results

Of the 572 patients with AH registered in the J-point registry, 220 were eligible for the analyses. The in-hospital mortality was 23.2%. The AUROC of the SOFA score (0.80; 95% CI: 0.72–0.86) was the highest among all factors. The other factors were serum potassium (0.65; 95% CI: 0.55–0.73), lactate (0.67; 95% CI: 0.57–0.75), quick SOFA (qSOFA) (0.55; 95% CI: 0.46–0.65), systemic inflammatory response syndrome (SIRS) (0.60; 95% CI: 0.50–0.69), and 5A severity scale (0.77; 95% CI: 0.68–0.84).

Discussion

Although serum potassium and lactate had relatively good discrimination ability as mortality predictors, the SOFA score had slightly better discrimination ability. The reason is that lactate and serum potassium were mainly reflected by the hemodynamic state; conversely, the SOFA score is a comprehensive score of organ failure, basing on six different scores from the respiratory, cardiovascular, hepatic, coagulation, renal, and neurological systems. Meanwhile, the qSOFA and SIRS scores underestimated the severity, with low discrimination abilities for mortality.

Conclusions

The SOFA score demonstrated better discrimination ability as a mortality predictor among all known prognostic factors in patients with AH.

Correction to: The development and validation of a "5A" severity scale for predicting in-hospital mortality after accidental hypothermia from J-point registry data

[This corrects the article DOI: 10.1186/s40560-019-0384-2.].

The development and validation of a "5A" severity scale for predicting in-hospital mortality after accidental hypothermia from J-point registry data

Background

Accidental hypothermia is a serious condition that requires immediate and accurate assessment to determine severity and treatment. Currently, accidental hypothermia is evaluated using the Swiss grading system which uses core body temperature and clinical findings; however, research has shown that core body temperature is not associated with in-hospital mortality in urban settings. Therefore, we developed and validated a severity scale for predicting in-hospital mortality among urban Japanese patients with accidental hypothermia.

Methods

Data for this multi-center retrospective cohort study were obtained from the J-point registry. We included patients with accidental hypothermia who were admitted to an emergency department. The total cohort was divided into a development cohort and validation cohort, based on the location of each institution. We developed a logistic regression model for predicting in-hospital mortality using the development cohort and assessed its internal validity using bootstrapping. The model was then subjected to external validation using the validation cohorts.

Results

Among the 572 patients in the J-point registry, 532 were ultimately included and divided into the development cohort (N = 288, six hospitals, in-hospital mortality 22.0%) and the validation cohort (N = 244, six hospitals, in-hospital mortality 27.0%). The 5 “A” scoring system based on age, activities-of-daily-living status, near arrest, acidemia, and serum albumin level was developed based on the variables’ coefficients in the development cohort. In the validation cohort, the prediction performance was validated.

Conclusion

Our “5A” severity scoring system could accurately predict the risk of in-hospital mortality among patients with accidental hypothermia.

Electronic supplementary material

The online version of this article (10.1186/s40560-019-0384-2) contains supplementary material, which is available to authorized users.

Prevalence and outcomes of accidental hypothermia among elderly patients in Japan: Data from the J-Point registry

AIM

We aimed to evaluate the prevalence and outcomes of accidental hypothermia (AH) among elderly patients in Japan.

METHODS

This was a multicenter chart review study of patients with AH (Japanese accidental hypothermia network registry; J-Point registry) that included patients with a body temperature ≤35 °C and those aged ≥18 years who visited the emergency department of 12 institutions in Japan from 1 April 2011 to 31 March 2016. The patients were classified into three groups: adult (aged 18-64 years), young-old (aged 65-79 years) and old-old (aged ≥80 years). The association between each age category and in-hospital mortality from AH was examined through a multivariable logistic regression analysis.

RESULTS

In total, 572 patients were registered in the J-Point registry database, of which 537 were included. The proportion of individuals who developed AH in an indoor setting was higher in the old-old group than in the adult group (86.9% [226/260] vs 61.1% [87/113]). The in-hospital mortality rates of the adult, young-old and old-old groups were 15.0% (17/113), 21.3% (35/164) and 30.4% (79/260), respectively. In the multivariable analysis, the in-hospital mortality rate was higher in the young-old and old-old groups than in the adult group (young-old vs adult, adjusted odds ratio: 2.31 and 95% confidence interval 1.16-4.64; old-old vs adult, adjusted odds ratio: 2.91 and 95% confidence interval 1.41-6.02).

CONCLUSIONS

Approximately 80% of patients with AH were aged ≥65 years. The in-hospital mortality rate of patients aged ≥65 years was significantly higher than that of those aged <65 years. Geriatr Gerontol Int 2018; 18: 1427-1432.

Prognostic factors for patients with accidental hypothermia: A multi-institutional retrospective cohort study

INTRODUCTION

In cases of severe accidental hypothermia (AH) in urban areas, the prognostic factors are unknown. We identified factors associated with in-hospital mortality in patients with moderate-to-severe AH in urban areas of Japan.

METHOD

The J-Point registry database is a multi-institutional retrospective cohort study for AH in 12 Japanese emergency departments. From this registry, we enrolled patients whose core body temperature was 32 °C or less on admission. In-hospital death was the primary outcome of this study. We investigated the association between each candidate prognostic factor and in-hospital death by applying the multivariate logistic regression analyses with adjusted odds ratios (AORs) and their 95% confidence interval [CI] as the effect variables.

RESULTS

Of 572 patients registered in the J-point registry, 358 hypothermic patients were eligible for analyses. Median body temperature was 29.2 °C (interquartile range, 27.0 °C-30.8 °C). In-hospital deaths comprised 26.3% (94/358) of all study patients. Factors associated with in-hospital death were age ≥ 75 years (AOR, 3.09; 95% CI, 1.31-7.27), need for assistance with activities of daily living (ADL; AOR, 3.06; 95% CI, 1.68-5.59), hemodynamic instability (AOR, 2.49; 95% CI, 1.32-4.68), and hyperkalemia (≥5.6 mEq/L; AOR, 2.65; 95% CI, 1.13-6.21).

CONCLUSION

The independent prognostic factors associated with in-hospital mortality of patients with moderate-to-severe AH in urban areas of Japan were age ≥ 75 years, need for assistance with ADL, hemodynamic instability, and hyperkalemia.

Characteristics and outcomes of accidental hypothermia in Japan: the J-Point registry

BACKGROUND

Accidental hypothermia (AH) has higher incidence and mortality in geriatric populations. Japan has a rapidly ageing population, and little is known about the epidemiology of hypothermia in this country.

METHODS

We created an AH registry based on retrospective review of patients visiting the ED of 12 institutions with temperature ≤35°C between April 2011 and March 2016. The severity of AH was classified as mild (≤35, ≥32°C), moderate (<32, ≥28°C) or severe (<28°C). The relationship between in-hospital mortality and severity of AH was assessed using a multivariable logistic regression analysis.

RESULTS

A total of 572 patients were registered in this registry and 537 patients were eligible for our analysis. The median age was 79 (IQR 66-87) years and the proportion of men was 51.2% (273/537). AH was more likely to occur in elderly patients aged ≥65 years (424/537, 80.0%) and in indoor settings (418/537, 77.8%). The condition most frequently associated with AH, irrespective of severity, was acute medical illness. A lower mean outside temperature was associated with a higher prevalence of AH, and particularly severe AH (p for trend <0.001). The overall proportion of cases resulting in in-hospital death was 24.4% (131/537), with no significant difference between severity levels observed in a multivariable logistic regression analysis (severe group (37/118, 31.4%) vs mild group (42/192, 21.9%), adjusted OR (AOR) 1.01, 95% CI 0.61 to 1.68; and moderate group (52/227, 22.9%) vs mild group, AOR 1.11, 95% CI 0.58 to 2.14).

CONCLUSION

Active prevention and intervention should occur for this important public health issue.

Resuscitative endovascular balloon occlusion of the aorta performed by emergency physicians for traumatic hemorrhagic shock: a case series from Japanese emergency rooms

Background

Resuscitative endovascular balloon occlusion of the aorta (REBOA), which has been increasingly used for the management of hemorrhagic shock, is a less invasive strategy for the management of patients with very severe hemorrhage. However, its effectiveness remains controversial.

Methods

This retrospective case series included trauma patients who underwent REBOA for hemorrhagic shock due to trauma in four Japanese tertiary care emergency centers from January 2013 to March 2017. Patients in cardiac arrest at the time of REBOA and those who underwent REBOA for nontraumatic causes during the study period were excluded.

Results

A total of 24 patients underwent REBOA during the study period. The median age was 52 years (interquartile range (IQR) 36.5–62.5), 17 (70.8%) of the patients were male, and 23 (95.8%) had blunt trauma. The 24-h survival was 50% (n = 12), and the in-hospital survival rate was 41.7% (10/24). In all cases, REBOA was performed in emergency rooms by emergency physicians without fluoroscopic guidance. Complications of REBOA were mesenteric ischemia (n = 1, 4.2%), ischemia of the lower extremities (n = 1, 4.2%), and placement of REBOA in thoracic aortic injury (n = 3, 12.5%).

Conclusions

REBOA can be an effective and feasible tool for controlling massive hemorrhage due to trauma. However, caution should be exercised regarding complications including placement of REBOA in aortic injury and limb ischemia in cases where REBOA is performed in an emergency department setting with minimal or no support from trauma surgeons.

Synthesis and growth mechanism of pentagonal bipyramid-shaped gold-rich Au/Ag alloy nanoparticles

Pentagonal bipyramid-shaped gold-rich Au/Ag alloy nanoparticles are synthesized in ethylene glycol (EG) in the presence of small amounts of AgNO3 and PVP without using Au seeds. The contents of Au and Ag in pentagonal nanobipyramids are determined by energy-dispersive X-ray spectroscopy (EDS). The EDS data demonstrates that this kind of nanoparticles is composed of Au/Ag alloys, not silver monolayers simply covering the surface of Au nanoparticles. Insights into the growth mechanism of pentagonal bipyramid-shaped gold-rich Au/Ag alloy nanoparticles are discussed.

Fast preparation of PtRu catalysts supported on carbon nanofibers by the microwave-polyol method and their application to fuel cells

PtRu alloy nanoparticles (24 +/- 1 wt %, Ru/Pt atomic ratios = 0.91-0.97) supported on carbon nanofibers (CNFs) were prepared within a few minutes by using a microwave-polyol method. Three types of CNFs with very different surface structures, such as platelet, herringbone, and tubular ones, were used as new carbon supports. The dependence of particles sizes and electrochemical properties on the structures of CNFs was examined. It was found that the methanol fuel cell activities of PtRu/CNF catalysts were in the order of platelet > tubular > herringbone. The methanol fuel cell activities of PtRu/CNFs measured at 60 degrees C were 1.7-3.0 times higher than that of a standard PtRu (29 wt %, Ru/Pt atomic ratio = 0.92) catalyst loaded on carbon black (Vulcan XC72R) support. The best electrocatalytic activity was obtained for the platelet CNF, which is characterized by its edge surface and high graphitization degree.