bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Study on Adsorbing Gaseous Formaldehyde with Novel Biomass Activated Carbons from Agriculture Wastes at Ambient Temperature
Authors: Gao Lei , Li Xian , Liu Yingyun , Xie Jinke , Li Caiting
Published: November 2020

To remove gaseous formaldehyde (HCHO) and rationally utilize agriculture wastes, chemical activation method using ZnCl2 as activating agent was employed to develop high-class biomass activated carbons (BACs) derived from agricultural straws for HCHO removal at ambient temperature. Proximate analysis and ultimate analysis testified that these agricultural straws were appropriate BACs precursors. BACs’ physicochemical properties were characterized by BET, SEM, FTIR and TGA, which demonstrated BACs with large specific surface area had the potential as ideal adsorbents. Systemic tests investigated the effects of activating agent (ZnCl2) and the concentrations of O2 and HCHO on adsorption performances of BACs, and compared them with two commercial activated carbons (CACs). Results showed ZnCl2 brought enormously positive effects but O2 had a prohibitive effect on the adsorption performance. BACs exhibited better performance than CACs, and BACM (BAC derived from maize straw) could obtain more than 80% removal efficiency under 1ppm HCHO after 40h. Desorption and regeneration tests were conducted to evaluate the security of the adsorbent and recycle regenerated adsorbent. The desorption temperature all above 50°C could ensure use security indoors. Saturated BACM through 1 or 2 run regeneration still exhibited better adsorption performance compared with virgin CAC from coal, indicating that the regeneration was significantly meaningful in practical application.
Analysis on Influencing Factors of Energy Consumption of Public Buildings in Cold Areas
Authors: Huang Cuicui , Liu Chunhua
Published: November 2020

DeST-c software was used to build the building model, and the single factor experiment method was used to carry out the simulation study. Under the condition that only single factor was changed and other influencing factors were unchanged, the influence law of each energy influencing factor on energy consumption was analyzed, and the influencing factors were Analysis of the impact degree on energy consumption, the results are as follows: body shape coefficient > outer window heat transfer coefficient > outer wall heat transfer coefficient > south window ratio > roof heat transfer coefficient > north window and wall ratio, namely, body shape coefficient, outer window transmission. The thermal coefficient and the external wall heat transfer coefficient are the main influencing factors of building energy consumption.
Human Factor Analysis in Dam Safety
Authors: Wang Huiwen , Li Dandan , Pan Shijia
Published: November 2020

Since introduced in the 1950s, human factor reliability analysis technology has been widely used in many important fields. However, as an area that also depends on people, dam safety management has not been specifically studied on it. This article focuses on the analysis of human factors in dam safety, puts forward its research significance and focus, and combines human factor research in other fields at home and abroad to propose relevant prospects.
Research on Temperature Control of Hospital Operating Room under Near Comfortable Conditions
Authors: Li Yuping
Published: November 2020

Air temperature has a significant impact on human thermal sensation. It directly affects the heat exchange between the human body and the environment. It is the most important factor in the PMV index that affects human thermal sensation. Clothing thermal resistance is also one of the factors that affect human thermal sensation PMV. In the operating room of a hospital building, because the clothing of the operating staff is different from that of the ordinary office environment staff, the corresponding clothing has different thermal resistance values, which will directly affect the design temperature setting of the operating room. Close to the comfort zone, when wearing surgical gowns, through Matlab programming, the relationship between the PMV value in the operating room and the indoor set temperature and air flow rate is explored in detail, in order to improve the working environment of the operating room personnel and the energy saving of the operating room air conditioning system Provide a reasonable basis.
Research on Satisfaction of Building Indoor Personnel
Authors: Sun Pengcheng , Yang Chuanjun , Xu Liangping , Guan Yuanhang , Wang Yanhui
Published: November 2020

In the operation stage, current green buildings gradually take energy conservation into consideration, a trend resulting in a phenomenon that environmental control system neglects suitability of indoor personnel. This article summarizes the advantages and disadvantages of several existing indoor thermal comfortability evaluation indicators by selectively analyzing common factors that affect personnel satisfaction, including personnel factors, indoor environmental factors, space factors, design factors, equipment factors, construction and property factors, and work factors. By combining the questionnaire to screen first-level impact factors, this article provides a basis for exploring a new multi-method-based evaluation method of intersection satisfaction.
Experimental study on the simultaneous nitrification and denitrification of limited aeration biofilm reactor
Authors: Zheng Peng-Sheng , Jin Li-Li , Gao Jie
Published: November 2020

To improve the nitrogen removal effects of domestic sewage and reactive mode, the two-stage limited aeration biofilm reactor was used to carry out an experiment. The pollutants removal effects and influencing factors were analyzed. The results indicate: Under the condition that the 1st reaction chamber DO of 1.5∼2 mg/L, the 2nd reaction chamber DO of 1∼1.5 mg/L, HRT=5 h, and influent ρ(COD) = 147∼181 mg/L, ρ(NH4
+-N) = 35.1∼43.6 mg/L, ρ(TN) = 36.3∼44.1 mg/L, the maximal concentration of COD, NH4
+-N, and TN in the last effluent were 18.8 mg/L, 0.35 mg/L and 14.2 mg/L, with the mean removal rates of 91.1%, 99.5%, 66.6% and the SND ratio of 62.7% ∼ 68.9%. Under the condition of 4.17h≤HRT≤5h, the effluent concentration of COD, NH4
+-N met the Category III of environmental quality standards for surface water (GB3838-2002), and the effluent concentration of TN met the Class A discharge standard of pollutants for municipal wastewater treatment plant (GB18918-2002) with the SND ratio of 65.7%. Under the condition that the 1st reaction chamber DO of 1.5∼2 mg/L, the 2nd reaction chamber DO of 1∼1.5 mg/L, HRT=4.17 h, the SND effects can be improved by the means of additional sodium acetate in the 2nd reaction chamber. The TN removal rate and SND ratio were respectively 75.4% and 75.8% at the optimal dosage of 40 mg/L.
Simulation of Double One-dimensional Two-phase Flow of Single Coated Propellant Internal Ballistic
Authors: Yin Jihong , Du Ping , Nan Fengqiang , Liu Dongyao
Published: November 2020

In this paper, based on the one-dimensional two-phase flow model, we established a model of a single coated propellant and wrote the corresponding software. Using software to simulate the internal ballistic process of a 105mm tank gun, the calculation results are compared with the experimental results of the actual coated propellant. The results show that the calculated values are in good agreement with the experimental values.
Effect of Silica Fume and Nano SiO2 on Properties of High Water Materials
Authors: Zheng Yuying , Xie Wei , Wang Qiufen , Shi Xianzheng , Xie Weizhang
Published: November 2020

In order to improve workability and strength of new high water materials, the influence of silica fume and nanometer on the physical and mechanical properties of high water materials was studied. By changing the content of silica fume or gas-phase nano-SiO2 in the new high-water materials, the workability of the materials was observed, and the strength of the materials at different ages was measured. The results showed that the increase of nano-SiO2 content significantly shortened the coagulation time of the high-water materials and improved the cohesion of the high-water materials. When the water-cement ratio was 1:1, the optimal content of silica fume was 3%, and the strength of the specimen in seven days was 43.7% higher than that of the original high-water material. At the water-cement ratio of 1.5:1, the optimal content of nano-SiO2 was 2%, and the strength of the specimen in seven days was 21.2% higher than that of the original high-water material. Through SEM scanning the microstructure of the material, it was found that the hydration reaction of the high-water material with nano-sio2 was more sufficient and the structure was denser.
Characterization of Various MnOx Doped CSAC and Its Application for Efficient Catalysis of Hydrogen Peroxide
Authors: Chen Qianru , Li Tianqi , Wan Junfeng , Han Song , Wang Yan
Published: November 2020

In the present work, the experiments of catalytic decomposition of hydrogen peroxide (H2O2) were carried out by using a series of prepared catalysts doped the coconut shell activated carbon (CSAC) under Fenton-like system. The relevant catalysts were prepared by the modified impregnation method. The effects of various catalysts had also been studied in the reaction system. The rate of catalytic decomposition of H2O2 was measured at regular time intervals. Besides, the optimum catalysts were characterized by SEM, EDX, BET, and XRD instruments. And it was demonstrated that the rich Mn3O4 and K2-xMn8O16 were beneficial for the catalytic activity, which may account for its superior catalytic efficiency.
The Design and Calculation of the Exoskeleton Backplate Based on the Composite Sandwich Structure
Authors: Peng Xuefeng , Dai Zongmiao , Liu Jiasheng , Wang Qingyuan
Published: November 2020

Aiming at the problem of heavy mechanical structure of the exoskeleton backplate, a lightweight backplate of T700 carbon fiber reinforced hollow glass microspheres/epoxy composite based on sandwich structure is proposed in this paper. By analyzing the influence of the thickness of face layer and core layer on the mechanical properties of composite sandwich structure, a composite backplate structure with face layer thickness of 4mm and core layer thickness of 8mm is designed. The simulation calculation and test of the sandwich backplate were carried out. The results show that the error between the simulation results and the experimental values is small, and the reliability of the results is high, which provides more lightweight design of the exoskeleton backplate.
The Summary of Synthesis and Theoretical Research into Cocrystal Explosives
Authors: Quan Kun
Published: November 2020

With the complexity of the using environment, traditional energetic materials can no longer meet the requirements, and it is urgent to synthesize new energetic materials. As a new type of explosive modification technology, cocrystallization is utilized widely in the field of energetic materials. The researchers mainly employ solvent method to synthesize different kinds of cocrystal explosives and utilise molecular dynamics simulation method to study the properties of different cocrystal explosives. In this paper, the theoretical research and experimental preparation of cocrystal explosives are summarized, and the application of cocrystal technology in energetic materials is analyzed. Both theoretically and experimentally, the results show that cocrystallization can improve the properties of explosives and provide a new and effective way for the modification of explosives.
Overview of Mechanical Behaviour of Corroded Steel Structures
Authors: Luo Lisheng , Xie Xinran , He Wenyuan
Published: November 2020

The corrosion imposes significantly effect on the mechanical behaviour of steel material and steel members, which can reduce the safety of steel structures. This paper presents current key research findings to promote the following research. This paper sets out the preparation methods available to gain corroded steel specimens firstly, then summarizes the correlation between corrosion and mechanical behaviour of corroded steel members and material.
Study on Synthesis and Properties of Vinyl Polyoxyethylene Ether Type Polycarboxylate Superplasticizer
Authors: Jiang Zhuojun , Fang Yunhui , Guo Yuanqiang , Lin Tianxing
Published: November 2020

Vinyl polyoxyethylene ether type polycarboxylate superplasticizer PCE-6C is prepared by copolymerization of vinyl polyoxyethylene ether and acrylic acid. The initiation system is a hydrogen peroxide-sodium formaldehyde sulfoxylate hydrate redox initiation system. The chain transfer agent is mercaptopropionic acid. The test results show that the monomer conversion rate of the synthesized PCE-6C is high and the dosage sensitivity of PCE-6C is significantly better than that of the conventional ester type polycarboxylate superplasticizer and the conventional ether type polycarboxylate superplasticizer, and the water consumption sensitivity and temperature sensitivity of PCE-6C is slightly better than that of the conventional ester type polycarboxylate superplasticizer and the conventional ether type polycarboxylate superplasticizer.
Analysis on the influencing factors of Shear lag effect of Double-sided Box Girder
Authors: Zhou Jingwen , He Shufa , Wu Zhida
Published: November 2020

In order to research different width-span ratio and aspect ratio on shear lag effect of double-sided box girder, the simple supported and cantilever systems are taken as research object. Simulating the shear lag effect is based on the finite element analysis software ANSYS. The conclusions of research are as follows: when width-span ratio η is 0.25∼0.5, the shear lag effect of the main beam varies the most under uniformly distributed load. With width-span ratio decreasing, the normal stress distribution tends to be more uniform. When aspect ratio decreases, the shear lag effect of double-box beam decreases gradually, but the variation amplitude is not big. Compared with aspect ratio, width-span ratio has a greater influence on the shear lag coefficient of double-sided box girder.
Influence of Loading Parameters of Mixed Charge on Ballistic Performance
Authors: Feng Qunshan , Chen Shanshan , Ma Yan , Nan Fengqiang , Du Pin , Liao Xin
Published: November 2020

In order to study the influence of loading parameters of mixed charge on its trajectory performance, the classical internal trajectory optimization model is adopted to control the consistency of other conditions and regularly change the shape, main charge quantity, arc thickness of main charge and arc thickness of auxiliary charge in mixed charge to calculate the internal trajectory performance data. When the main charge weight is 1780g, the arc thickness of the main charge is 1 mm, and the arc thickness of the auxiliary charge is 0.48mm, the data changes of the ballistic performance with the other three variables are analyzed. The results show that the influence of the main charge arc thickness of the corresponding step length on the ballistic properties of the mixed charge is more obvious than that of the main charge quantity and the auxiliary charge arc thickness of the corresponding step length. The increase of arc thickness will lead to the decrease of muzzle velocity, the decrease of bore pressure and the increase of relative combustion position of gunpowder. The increase of charge volume will lead to the increase of muzzle velocity, the increase of bore pressure and the decrease of the end position of gunpowder combustion velocity. Compared with porous powder, tubular powder has higher initial velocity, smaller gunpowder end position and higher bore pressure.
How religion has changed
Authors: Tweed Thomas A.
Published: November 2020

“How religion has changed,” looks at how the past shapes the present, and how responsible citizenship today requires some sense of history. Too often public discussions of the religious dimensions of policy issues either overlook the past or highlight recent years. But this shortened perspective makes it difficult to see what is new and what is not—and which problems, like climate change, economic inequality, and interreligious violence, are entangled in a longer past. Religion emerged long ago and has played a role in some of the big lifeway transitions—from foraging to farming to factories. There are four altered ways of imagining (new metaphors), making (new technologies), performing (new rituals), and gathering (new communities)—and the with these, there are challenges that accompanied each new religious habitat.
Montaigne: A Very Short Introduction
Authors: Hamlin William M.
Published: November 2020

Montaigne: A Very Short Introduction provides an overview of Michel de Montaigne’s life, thought, and writing. This VSI situates Montaigne’s influential Essays within his lived experience. Montaigne was a member of the minor aristocracy, a judicial investigator in his youth, and a traveler in later life. He also held the office of mayor and acted as a diplomatic link in war-torn France. Montaigne explored debates and dualities that would inspire future French philosophers, comparing marriage with friendship, solitude with sociability, and the Old World with the New. As a philosopher, he is seen as an early modern skeptic, but his broad-minded approach continues to inspire writers today.
Introduction
Authors: Green Nile
Published: November 2020

What is global Islam, and where did it come from? The Introduction defines “global Islam” as the doctrines and practices promoted by transnational religious activists, organizations, and states during the era of modern globalization. These processes involve Africa and Asia as much as the Middle East and the West. Globalization has enabled the emergence and proliferation of many different versions of Islam, both political and expressly nonpolitical. Communications of these beliefs and ideologies have been shaped by new forms of mobility, communication, organization, and finance. Global Islam is the result of a historical process: the interplay between religion and globalization.
Long-Term Habitual Vigorous Physical Activity Is Associated With Lower Visit-to-Visit Systolic Blood Pressure Variability: Insights From the SPRINT Trial
Authors: Xu Xiaoyong , Meng Xianghong , Oka Shin-ichi
Published: November 2020

Background

Our work aimed to investigate the association between vigorous physical activity and visit-to-visit systolic blood pressure variability (BPV).

Methods

We conducted a post hoc analysis of SPRINT (Systolic Blood Pressure Intervention Trial), a well-characterized cohort of participants randomized to intensive (<120 mm Hg) or standard (<140 mm Hg) systolic blood pressure targets. We assessed whether patients with hypertension who habitually engage in vigorous physical activity would have lower visit-to-visit systolic BPV compared with those who do not engage in vigorous physical activity. Visit-to-visit systolic BPV was calculated by SD, average real variability (ARV), and SD independent of the mean (SDIM) using measurements taken during the 1-, 2-, 3-, 6-, 9-, and 12-month study visits. A medical history questionnaire assessed vigorous physical activity, which was divided into 3 categories according to the frequency of vigorous physical activity.

Results

A total of 7,571 participants were eligible for analysis (34.8% female, mean age 67.9 ± 9.3 years). During a follow-up of 1-year, vigorous physical activity could significantly reduce SD, ARV, and SDIM across increasing frequency of vigorous physical activity. There were negative linear trends between frequency of vigorous physical activity and visit-to-visit systolic BPV.

Conclusions

Long-term engagement in vigorous physical activity was associated with lower visit-to-visit systolic BPV.

Clinical trials registration

SPRINT (Systolic Blood Pressure Intervention Trial); Trial Number: NCT01206062, https://clinicaltrials.gov/ct2/show/NCT01206062.
The anatomy, movement, and functions of human sperm tail: an evolving mystery
Authors: Kumar Naina , Singh Amit Kant
Published: November 2020

Sperms have attracted attention of many researchers since it was discovered by Antonie van Leeuwenhoek in 1677. Though a small cell, its every part has complex structure and different function to play in carrying life. Sperm tail is most complicated structure with more than 1000 proteins involved in its functioning. With the advent of three-dimensional microscopes, many studies are undergoing to understand exact mechanism of sperm tail movement. Most recent studies have shown that sperms move by spinning rather than swimming. Each subunit of tail, including axonemal, peri-axonemal structures, plays essential roles in sperm motility, capacitation, hyperactivation, fertilization. Furthermore, over 2300 genes are involved in spermatogenesis. A number of genetic mutations have been linked with abnormal sperm flagellar development leading to motility defects and male infertility. It was found that 6% of male infertility cases are related to genetic causes, and 4% of couples undergoing intracytoplasmic sperm injection for male subfertility have chromosomal abnormalities. Hence, an understanding of sperm tail development and genes associated with its normal functioning can help in better diagnosis of male infertility and its management. There is still a lot that needs to be discovered about genes, proteins contributing to normal human sperm tail development, movement, and role in male fertility. Sperm tail has complex anatomy, with surrounding axoneme having 9 + 2 microtubules arrangement along its entire length and peri-axonemal structures that contribute in sperm motility and fertilization. In future sperm tail-associated genes, proteins and subunits can be used as markers of male fertility.
A Novel Case of Homozygous Interferon Alpha/Beta Receptor Alpha Chain (IFNAR1) Deficiency With Hemophagocytic Lymphohistiocytosis
Authors: Gothe Florian , Hatton Catherine F , Truong Linh , Klimova Zofia , Kanderova Veronika , Fejtkova Martina , Grainger Angela , Bigley Venetia , Perthen Joanna , Mitra Dipayan , Janda Ales , Fronkova Eva , Moravcikova Dusana , Hambleton Sophie , Duncan Christopher J A
Published: November 2020

We present a case of complete deficiency of the interferon alpha/beta receptor alpha chain (IFNAR1) in a child with fatal systemic hyperinflammation, apparently provoked by live-attenuated viral vaccination. Such pathologic hyperinflammation, fulfilling criteria for hemophagocytic lymphohistiocytosis, is an emerging phenotype accompanying inborn errors of type I interferon immunity.
Long COVID in the Faroe Islands: A Longitudinal Study Among Nonhospitalized Patients
Authors: Petersen Maria Skaalum , Kristiansen Marnar Fríðheim , Hanusson Katrin Dahl , Danielsen Marjun Eivindardóttir , á Steig Bjarni , Gaini Shahin , Strøm Marin , Weihe Pál
Published: November 2020

Background

Little is known about long-term recovery from coronavirus disease 2019 (COVID-19) disease, especially in nonhospitalized individuals. In this longitudinal study we present symptoms registered during the acute phase as well as long COVID (ie, long-lasting COVID-19 symptoms) in patients from the Faroe Islands.

Methods

All consecutive patients with confirmed reverse transcription–polymerase chain reaction testing from April to June 2020 were invited to participate in this study for the assessment of long COVID. Demographic and clinical characteristics and self-reported acute and persistent symptoms were assessed using a standardized detailed questionnaire administered at enrollment and at repeated phone interviews in the period 22 April to 16 August.

Results

Of the 180 participants (96.3% of the 187 eligible COVID-19 patients), 53.1% reported persistence of at least 1 symptom after a mean of 125 days after symptoms onset, 33.0% reported 1 or 2 symptoms, and 20.1% reported 3 or more symptoms. At the last follow-up, 46.9% were asymptomatic compared with 4.4% during the acute phase. The most prevalent persistent symptoms were fatigue, loss of smell and taste, and arthralgias.

Conclusions

Our results show that it might take months for symptoms to resolve, even among nonhospitalized persons with mild illness course in the acute phase. Continued monitoring for long COVID is needed.
The spectrum of functional responses during ABCDE stress echocardiography
Authors: Zagatina A , Ciampi Q , Cortigiani L , Borguezan-Daros C , De Castro E Silva Pretto J.L , Wierzbowska-Drabik K , Zanella H , Merlo P.M , Djordjevic-Dikic A , Boshchenko A , Arbucci R , Monte I , Lowenstein J , Rigo F , Picano E
Published: November 2020

Background

The new methodological standard in stress echo (SE) is the comprehensive approach with ABCDE protocol: step A for regional wall motion abnormalities (RWMA); step B for B-lines by lung ultrasound; step C for left ventricular contractile reserve (LVCR); step D for Doppler-based coronary flow velocity reserve (CFVR) in left anterior descending coronary artery; and step E for imaging-independent EKG-based heart rate reserve (HRR).

Purpose

To assess the feasibility of ABCDE-SE in a prospective, large scale, multicenter, international, effectiveness study.

Methods

From September 2016 to December 2019, we enrolled 4,585 all-comers patients (age 63±11 years, 2,566 males, 56%; ejection fraction 61±9%) with known or suspected chronic coronary artery disease referred to clinically-driven SE with exercise (n=1,774, 38.7%), dipyridamole (n=2,403, 52.4%), dobutamine (n=375, 8.2%) or adenosine (n=33, 0.7%). Recruitment involved 13-certified laboratories of 7 countries. All patients underwent ABCDE-SE. The same transducer was used for cardiac and lung scan. Criteria for abnormal response were: stress-induced changes in RWMA in 2 contiguous segments for step A; stress-rest increase in B-lines ≥2 for step B (4-site simplified scan, each site scored from 0= A-lines or black lung to 10= white lung for coalescing B-lines); LVCR ≤2.0 for exercise and dobutamine (≤1.1 for vasodilators) for step C; CFVR in LAD ≤2.0 for step D; HRR (peak/rest heart rate) ≤1.80 for exercise and dobutamine (≤1.22 for vasodilators) for step E.

Results

Success rate was 98%, 100%, 99%, 86% and 100% for A, B, C, D and E steps, respectively. The positivity rate was 19% for A, 27% for B, 35% for C, 27% for D and 37% for E. All 5 parameters were normal in 1,496 patients (32.6%), all 5 were abnormal in 183 patients (4.0%). Most patients had abnormal response of 1 (n=1,356, 29.6%), 2 (n=788, 17.2%), 3 (n=477, 9.7%) or 4 (n=315, 6.9%) criteria (see Figure).

Conclusions

ABCDE-SE is extremely feasible, user-friendly, with minimal increase in imaging and off-line analysis time. It allows a comprehensive and personalized functional stratification assessing different vulnerabilities: epicardial coronary artery stenosis (step A), pulmonary congestion (step B), global myocardial dysfunction (step C), coronary microcirculatory dysfunction (step D), and cardiac autonomic nervous system imbalance (step E). The SE response is not only black and white with step A but can be effectively titrated from benign green code (all steps negative) to more functionally malignant red code (at least 3 steps positive).

Figure 1

Funding Acknowledgement

Type of funding source: None
Parameters of left atrial during stress in patients with asymptomatic primary mitral regurgitation
Authors: Zvirblyte R , Tamulenaite E , Saniukaite A , Merkyte I , Mizariene V , Ereminiene E , Vaskelyte J.J
Published: November 2020

Introduction

Progressive volume overload caused by chronic mitral regurgitation (MR) leads to left atrium (LA) and left ventricle (LV) remodeling. Despite these structural changes, most of MR patients may remain asymptomatic for a long time. LA enlargement and reduced LA deformation parameters in asymptomatic MR patients predict a worse prognosis and may provide additional information to guide for earlier surgery.

Purpose

The aim of the study was to evaluate changes of LA size and deformation parameters in patients with asymptomatic primary MR during stress.

Methods

84 asymptomatic patients (age 59.87±13.47 years) with sinus rhythm and preserved left ventricle (LV) ejection fraction (EF) (>50%) at rest were included in the study. Resting and stress (veloergometry as per protocol 25 + 25 W every 3 minutes) echocardiography and speckle tracking off-line analyses were performed to 52 (61.9%) patients with moderate MR (MR group) and 32 (38.1%) patients without significant heart valves disease (control group). Statistical analyses were performed using the SPSS 20.0 software. The value of p<0.05 was considered as statistically significant.

Results

Volume index of LA was significantly higher in subjects with MR (picture 1). LA area was similar in MR and control groups at rest. However, during stress LA area became significantly larger in MR group (picture 1). LA myocardial deformation parameters were calculated during 3 phases of LA cycle: reservoir phase strain (LASr), conduit phase strain (LAScd), contraction phase strain (LASct). At rest, during peak stress and at recovery phase all of them were higher in controls but difference was not significant. During initial stress (25 W) LAScd was significantly higher in MR group (−16.86±−8.06% vs. −11.33 ±−6.26% p=0.034), while healthy subjects had a tendency to lower LASr (20.32±10.53% vs. 22.7±10.89%, p=0.535) (picture 1). Better LV EF at rest was related to smaller LA area (p=0.003, r – 0.390) and volume index (p=0.020, r – 0.308) during peak stress.

Conclusions

Stress provokes significant increase of LA size (volume and area) and LAScd in patients with primary mitral regurgitation. Other myocardial deformation parameters of LA were not significantly related to MR. LV EF at rest correlates with LA parameters during peak stress.

Changes of LA parameters during stress

Funding Acknowledgement

Type of funding source: None
The five-beat averaged method of assessing aortic stenosis in atrial fibrillation significantly underestimates stenosis severity compared to sinus rhythm
Authors: Tomlinson S , Mandala A , Hayman S , Scalia G
Published: November 2020

Background

Doppler echocardiographic assessment of aortic stenosis (AS) is dependent on trans-valvular flow rate (TVFR) and is most accurately performed in physiologically normal conditions (TVFR >200ml/s). Atrial fibrillation (AF) complicates AS assessment with heart rate variability and reduced averaged indexed stroke volume (SVi) compared to sinus rhythm (SR). We hypothesize that the 5-beat averaging technique in AF leads to underestimation of severity of AS compared to SR, and that diagnostic accuracy may be improved by maximum SVi beat selection.

Methods

Patients with at least mild AS (mean aortic gradient (MG) >15mmHg) with separate echocardiograms demonstrating SR and AF within a six-month period were identified. Patients with interval cardiac surgery, change in left ventricular ejection fraction (LVEF) of >15%, aortic valve prostheses, infective endocarditis, paced rhythm, severe concomitant valvular dysfunction, LVEF <35%, heart rate >100 beats per minute (bpm) or TVFR <200ml/s on their SR examination were excluded. In AF, individual beat SVi was calculated from individual beat aortic velocity time integral (VTI) and the reported aortic valve area (AVA) via the continuity equation.

Results

Seventeen patients were identified (mean time between echocardiograms 132 days, mean difference in LVEF 4%, mean difference in heart rate 11bpm). Using the 5-beat averaged model, compared to SR, the presence of AF significantly reduced SVi (−12.68ml/m2, p=0.00007) and TVFR (−69ml/s, p=0.00014). In AF, 9/17 cases demonstrated one or more beats with TVFR <200ml/s, with 6/17 producing a 5-beat averaged TVFR <200ml/s – consistent with a low flow state. Correspondingly, flow derived severity assessment parameters and calculated aortic valve area (AVA) in AF were reduced compared to SR (aortic peak velocity (Vmax) −0.42m/s, p=0.00005, MG −7.01mmHg, p=0.002, AVA −0.11cm2, p=0.025). As a proposed correction in AF, the single beat with the largest SVi was compared with SR. This measure improved concordance with flow conditions and severity assessment in SR (difference SVi −8.77ml/m2, p=0.004, TVFR −46ml/s, p=0.001, Vmax −0.21, p=0.003, MG −3.55mmHg, p=0.02) and equalized calculated AVA (−0.07cm2, p=0.09).

Conclusion

In individual patients with AS observed in SR and AF within a six-month period, AF was associated with significantly lower SVi and TVFR, with underestimation of AS severity assessment. AS assessment in AF using maximum observed stroke volume beat (as opposed to 5-beat average) improves concordance with SR assessment significantly.

Funding Acknowledgement

Type of funding source: None
A novel echocardiographic-derived classification after LAA closure can accurately predict incomplete ostial closure and significant peri-device leaks
Authors: Hamadanchi A , Ijuin S , Haertel F , Baez L , Franz M , Schulze C , Moebius-Winkler S
Published: November 2020

Background

The assessment of residual peri-device leaks (PDL) after percutaneous left atrial appendage closure (LAAC) remains crucial in the post-procedural management. Clinical significance of PDL is still poorly understood and echocardiographic recognition of PDL remains challenging. This study aimed to verify a novel proposed echocardiographic classification for prediction of clinically significant PDL following LAAC.

Methods

We retrospectively evaluated our echocardiographic data of 72 patients who underwent percutaneous LAAC at the University Hospital Jena between September 2015 - 2018. All echo images were transferred to a workstation for offline analysis by two independent investigators. Total number of studies was 127. We proposed a morphological classification of LAA devices (Fig. 1A-C) based on the amount of echodensity and luceny inside the devices into three types: type A: homogenous echodensity in 0, 45, 90 and 135°; indicating completely thrombosed device, type B with inhomogeneous echo-lucencies (<50% of device) and type C: partially thrombosed device with echo-lucencies >50% of total, which we labeled “ice-cream cone” sign. Each type was then matched to the degree of PDL and other clinical and paraclinical parameters.

Results

Tab.1 shows patient's characteristics. PDL was found in 21% of patients. Four patients showed regression of PDL after 160 days. Patients with type C had the most percentage of PDL in three types at 6 months follow-up (type A: 7%, type B: 33%, type C 100%, p<0.001). Device size in patients with type C was largest in three types (type A: 25.9±3.6mm, type B: 25.8±3.4mm, type C 29.8±3.0mm, type A vs. B, p=0.018; type B vs. C, p=0.007). Mean compression rate after 45 days was 21±9.3% in type A vs. 14±7.4% in type C (p=0.022). Ice cream sign showed a sensitivity of 53.1%, specificity of 100% and positive predictive value of 100% for prediction of PDL.

Conclusion

Our data demonstrate that: 1) This novel classification irrespective of anticoagulation regimen, can accurately discriminate among various degrees of PDL, in such that type C or “ice cream sign” has a very high positive predictive value for PDL (100%). 2) Type A, the ideal type, is associated with smaller landing zones and a higher compression rate.

Funding Acknowledgement

Type of funding source: None
Fully automated contrast and non-contrast cardiac view detection in echocardiography a multi-centre, multi-vendor study
Authors: Gao S , Stojanovski D , Parker A , Marques P , Heitner S , Yadava M , Upton R , Woodward G , Lamata P , Beqiri A , Leeson P
Published: November 2020

Background

Correctly identifying views acquired in a 2D echocardiographic examination is paramount to post-processing and quantification steps often performed as part of most clinical workflows. In many exams, particularly in stress echocardiography, microbubble contrast is used which greatly affects the appearance of the cardiac views. Here we present a bespoke, fully automated convolutional neural network (CNN) which identifies apical 2, 3, and 4 chamber, and short axis (SAX) views acquired with and without contrast. The CNN was tested in a completely independent, external dataset with the data acquired in a different country than that used to train the neural network.

Methods

Training data comprised of 2D echocardiograms was taken from 1014 subjects from a prospective multisite, multi-vendor, UK trial with the number of frames in each view greater than 17,500. Prior to view classification model training, images were processed using standard techniques to ensure homogenous and normalised image inputs to the training pipeline. A bespoke CNN was built using the minimum number of convolutional layers required with batch normalisation, and including dropout for reducing overfitting. Before processing, the data was split into 90% for model training (211,958 frames), and 10% used as a validation dataset (23,946 frames). Image frames from different subjects were separated out entirely amongst the training and validation datasets. Further, a separate trial dataset of 240 studies acquired in the USA was used as an independent test dataset (39,401 frames).

Results

Figure 1 shows the confusion matrices for both validation data (left) and independent test data (right), with an overall accuracy of 96% and 95% for the validation and test datasets respectively. The accuracy for the non-contrast cardiac views of >99% exceeds that seen in other works. The combined datasets included images acquired across ultrasound manufacturers and models from 12 clinical sites.

Conclusion

We have developed a CNN capable of automatically accurately identifying all relevant cardiac views used in “real world” echo exams, including views acquired with contrast. Use of the CNN in a routine clinical workflow could improve efficiency of quantification steps performed after image acquisition. This was tested on an independent dataset acquired in a different country to that used to train the model and was found to perform similarly thus indicating the generalisability of the model.

Figure 1. Confusion matrices

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Ultromics Ltd.
Exercise capacity is associated with rest and peak-exercise left ventricular global longitudinal strain in patients with hypertrophic cardiomyopathy
Authors: Fava A.M , Alashi A , Saijo Y , Sande Mathias I , Popovic Z , Thamilarasan M , Lever H , Desai M.Y
Published: November 2020

Background

Patients with hypertrophic cardiomyopathy (HCM) frequently have reduced exercise capacity, which can be associated with subclinical cardiac dysfunction. Left ventricle global myocardial strain (LV-GLS) is a sensitive index to detect subclinical myocardial dysfunction. However, the clinical utility of LV-GLS during exercise test remains uncertain.

Purpose

We assessed the association of functional capacity with LV-GLS at rest and at the peak of stress in HCM patients.

Methods

We examined 566 asymptomatic/minimally symptomatic HCM patients (54±14 years, 57% men, body mass index 30±6 kg/m2, 84% on beta-blockers) by echo at rest and following maximal exercise. We recorded clinical, echo variables (LV ejection fraction [LVEF], LV thickness, left ventricle mass index [LVMI], left ventricle outflow tract [LVOT] gradient, LV-GLS at rest and at peak stress), and exercise variables (percent of age-gender predicted metabolic equivalents [AGP-METs]).

Results

Echo parameters were as follows: LVEF at rest of 62±6%, wall thickness of 16.9±0.4 mm, LVMI of 117±47 g/m2, LVOT gradient at rest of 27±33 mmHg, LV-GLS at rest of −15.9±3.6%, LV-GLS at peak of stress of −17.4±4.3%, and change in LV strain from rest to stress of −1.9±2.3%. Only 41% of patients achieved >85% of AGP-METs. Logistic regression demonstrating an association between AGP-METs less than 85% and various predictors are shown in Table 1.

Conclusion

Impaired deformation at peak of stress assessed by LV-GLS was associated with reduced exercise capacity measured as AGP-METs less than 85%. These findings suggest that early systolic cardiac deterioration should be considered as a cause of exercise impairment in patients with HCM.

Funding Acknowledgement

Type of funding source: None
Cardiac time intervals predict major adverse cardiovascular events in individuals with type 1 diabetes without known heart disease
Authors: Brainin P , Lassen M.C.H , Joergensen P.G , Biering-Soerensen T , Andersen H.U , Rossing P , Jensen M.T
Published: November 2020

Background

Cardiac time intervals, and in particular the myocardial performance index (MPI) which combines systolic and diastolic function, are associated with cardiovascular prognosis in various populations. We aimed to investigate if cardiac time intervals offer prognostic information on cardiovascular risk in individuals with type 1 diabetes (T1DM).

Methods

We prospectively included 1,088 individuals with T1DM without known heart disease (mean age 50±15 years; 53% male; duration of diabetes 26±15 years; 30% had albuminuria). All enrolled individuals underwent an echocardiographic examination with assessment of cardiac time intervals by color Tissue Doppler imaging M-mode. We evaluated the isovolumetric relaxation and contraction time (IVRT; IVCT) and ejection time (ET). The MPI was calculated as [(IVRT+IVCT)/ET]. In Cox proportional hazards models, we assessed major adverse cardiovascular events (MACE), a composite of incident heart failure or hospitalization for acute coronary syndrome or PCI/CABG. Multivariable models were adjusted for clinical information, pharmacotherapy and echocardiographic parameters.

Results

During the median follow-up time of 6 years [IQR 6, 7 years], 106 (10%) experienced MACE. In adjusted survival analyses the IVRT (HR: 1.13 per 10ms increase [1.01 to 1.26], P=0.026) and MPI (HR: 1.03 per 1 unit increase [1.01 to 1.04], P=0.005) were associated with MACE. Overall, the association between IVCT and outcome was borderline significant (HR: 1.15 per 10ms increase [0.97 to 1.36], P=0.10) while there was no association for ET (HR: 0.97 per 10ms increase [0.89 to 1.05], P=0.43). Sex modified the association for IVCT (P interaction<0.05) such that IVCT (HR: 1.23 per 10ms increase [1.02 to 1.49], P=0.027) and MPI (HR 1.03 per 1 unit increase [1.01 to 1.05], P=0.005; Figure) were associated with MACE in women but not in men.

Conclusion

Cardiac time intervals are positively associated with MACE in T1D without known heart disease. Furthermore, the association is modified by sex in that the IVCT and MPI provide independent and prognostic information on the risk of future cardiovascular events particularly in female individuals while not significant in men. These findings suggest sex differences in myocardial impairment related to T1D.

Association between MACE and MPI in DM1

Funding Acknowledgement

Type of funding source: None
Prognostic utility of early systolic lengthening by speckle tracking echocardiography in patients with type 2 diabetes
Authors: Brainin P , Jensen M.T , Biering-Soerensen T , Moegelvang R , Fritz-Hansen T , Vilsboell T , Rossing P , Joergensen P.G
Published: November 2020

Background

Early systolic lengthening (ESL) has recently recognized as a predictor of cardiovascular events in patients with myocardial ischemia. Our aim was to evaluate the prognostic value of ESL in patients with type 2 diabetes.

Methods

In this prospective study we conducted speckle tracking examinations in 743 patients with type 2 diabetes (62% male; age 63±10 years; diabetes duration 11 [5, 17] years). Patients were free from interventricular conduction disturbances, atrial fibrillation, heart failure and ischemic heart disease at study inclusion. We assessed the ESL index, defined as: (−100 x [peak positive systolic strain / global longitudinal strain (GLS)]), and duration of ESL, defined as time from onset of QRS complex on the electrocardiogram to time of peak positive systolic strain. Measurements were averaged from 18 myocardial segments.

Results

During the median follow-up time of 4.8 years [IQR 4, 5.3 years], 93 (13%) patients experienced major adverse cardiovascular events (MACE), a composite of incident heart failure, myocardial infarction and cardiovascular death. Because GLS modified the association with MACE (P interaction <0.05), the population was stratified by the median GLS value (low >−15% and high ≤−15%). In patients with low GLS, the ESL index (HR 1.47 per 1% increase [1.12 to 1.93], P=0.005) and ESL duration (HR 1.73 per 1ms increase [1.10 to 2.72], P=0.017) were associated with MACE. Both associations remained significant in multivariable models adjusted for clinical, echocardiographic and speckle tracking measurements (Figure). No associations were found in patients with high GLS (Figure).

Conclusion

Assessment of ESL yields novel and independent prognostic information on major adverse cardiovascular events in patients with diabetes type 2 and reduced longitudinal strain.

Forest plot: ESL and risk of MACE by GLS

Funding Acknowledgement

Type of funding source: None
Echocardiographic predictors of atrial fibrillation in middle-aged patients without overt heart disease
Authors: Borizanova-Petkova A , Georgieva N , Kinova E , Goudev A , Koleva V
Published: November 2020

Background

Left atrial volume index (LAVi) has been established as a surrogate marker for chronically elevated left ventricular (LV) filling pressure. Moreover it is a powerful predictor of atrial fibrillation (AF) in different pathologies. However, there is limited data for additional and sensitive echocardiographic predictors of AF in patients without over heart disease.

Purpose

To investigate middle- aged AF patients without overt heart disease and to identify additional echocardiographic predictors of AF.

Methods

A total of 936 consecutive patients with AF, who had been admitted for sinus rhythm restoriation in our hospital for the period January 2016- December 2018, were screened for participation in the study. Only 70 patients met the inclusion criteria- stable sinus rhythm, age between 40–60 years, without over heart disease. They were separated in 2 groups: with new onset AF (n=33) and recurrent AF (n=37); 30 healthy subjects were enrolled in the control group. All patients underwent two dimensional echocardiographic assessment with volumetric and speckle tracking analyses.

Results

There were significant differences between all groups in: LAVi; LA total (LATEF), passive (LAPEF) and active (LAAEF) emptying fractions; LA reservoir (LASr), conduit (LAScd) and contractile (LASct) strain; LV global longitudinal strain (GLS), but not in other LV indices – table. Multiple regression analysis demonstrated that LAVi (B=0.012, p=0.05, 95% CI: 0.000–0.023), LASr (B=−0.055, p=0.0001, 95% CI: −0.071 to −0.039), LASct (B=0.041, p=0.001, 95% CI: 0.016–0.066) are independent predictors of AF.

Conclusion

In middle- aged patients without overt heart disease LASr and LASct have additive value beyond LAVi in prediction of AF.

Funding Acknowledgement

Type of funding source: None