bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Soil Warming and Permafrost Thaw Increase CH4 Emissions in an Upland Tundra Ecosystem
Authors: Taylor M. A. , Celis G. , Ledman J. D. , Mauritz M. , Natali S. M. , Pegoraro E.‐F. , Schädel C. , Schuur E. A. G.
Published: October 2021

Rapid Arctic warming is causing permafrost to thaw and exposing large quantities of soil organic carbon (C) to potential decomposition. In dry upland tundra systems, subsidence from thawing permafrost can increase surface soil moisture resulting in higher methane (CH4) emissions from newly waterlogged soils. The proportion of C released as carbon dioxide (CO2) and CH4 remains uncertain as previously dry landscapes transition to a thawed state, resulting in both wetter and drier microsites. To address how thaw and moisture interact to affect total C emissions, we measured CH4 and CO2 emissions from paired chambers across thaw and moisture gradients created by nine years of experimental soil warming in interior Alaska. Cumulative growing season (May–September) CH4 emissions were elevated at both wetter (216.1–1,099.4 mg CH4‐C m−2) and drier (129.7–392.3 mg CH4‐C m−2) deeply thawed microsites relative to shallow thaw (55.6–215.7 mg CH4‐C m−2) and increased with higher deep soil temperatures and permafrost thaw depth. Interannual variability in CH4 emissions was driven by wet conditions in graminoid‐dominated plots that generated >70% of emissions in a wet year. Shoulder season emissions were equivalent to growing season CH4 emissions rates in the deeply thawed, warmed soils, highlighting the importance of non‐growing season CH4 emissions. Net C sink potential was reduced in deeply thawed wet plots by 4%–42%, and by 3.5%–8% in deeply thawed drier plots due to anaerobic respiration, suggesting that some dry upland tundra landscapes may transition into stronger CH4 sources in a warming Arctic.
Altered functional brain dynamics in chromosome 22q11.2 deletion syndrome during facial affect processing
Authors: Cornblath Eli J. , Mahadevan Arun , He Xiaosong , Ruparel Kosha , Lydon-Staley David M. , Moore Tyler M. , Gur Ruben C. , Zackai Elaine H. , Emanuel Beverly , McDonald-McGinn Donna M. , Wolf Daniel H. , Satterthwaite Theodore D. , Roalf David R. , Gur Raquel E. , Bassett Dani S.
Published: October 2021

Chromosome 22q11.2 deletion syndrome (22q11.2DS) is a multisystem disorder associated with multiple congenital anomalies, variable medical features, and neurodevelopmental differences resulting in diverse psychiatric phenotypes, including marked deficits in facial memory and social cognition. Neuroimaging in individuals with 22q11.2DS has revealed differences relative to matched controls in BOLD fMRI activation during facial affect processing tasks. However, time-varying interactions between brain areas during facial affect processing have not yet been studied with BOLD fMRI in 22q11.2DS. We applied constrained principal component analysis to identify temporally overlapping brain activation patterns from BOLD fMRI data acquired during an emotion identification task from 58 individuals with 22q11.2DS and 58 age-, race-, and sex-matched healthy controls. Delayed frontal-motor feedback signals were diminished in individuals with 22q11.2DS, as were delayed emotional memory signals engaging amygdala, hippocampus, and entorhinal cortex. Early task-related engagement of motor and visual cortices and salience-related insular activation were relatively preserved in 22q11.2DS. Insular activation was associated with task performance within the 22q11.2DS sample. Differences in cortical surface area, but not cortical thickness, showed spatial alignment with an activation pattern associated with face processing. These findings suggest that relative to matched controls, primary visual processing and insular function are relatively intact in individuals with 22q11.22DS, while motor feedback, face processing, and emotional memory processes are more affected. Such insights may help inform potential interventional targets and enhance the specificity of neuroimaging indices of cognitive dysfunction in 22q11.2DS.
Polygenic scores: prediction versus explanation
Authors: Plomin Robert , von Stumm Sophie
Published: October 2021

During the past decade, polygenic scores have become a fast-growing area of research in the behavioural sciences. The ability to directly assess people’s genetic propensities has transformed research by making it possible to add genetic predictors of traits to any study. The value of polygenic scores in the behavioural sciences rests on using inherited DNA differences to predict, from birth, common disorders and complex traits in unrelated individuals in the population. This predictive power of polygenic scores does not require knowing anything about the processes that lie between genes and behaviour. It also does not mandate disentangling the extent to which the prediction is due to assortative mating, genotype–environment correlation, or even population stratification. Although bottom-up explanation from genes to brain to behaviour will remain the long-term goal of the behavioural sciences, prediction is also a worthy achievement because it has immediate practical utility for identifying individuals at risk and is the necessary first step towards explanation. A high priority for research must be to increase the predictive power of polygenic scores to be able to use them as an early warning system to prevent problems.
A proposed redesign of elective cataract services in Scotland – pilot project
Authors: Dhillon Niku , Ghazal Dina , Harcourt Jane , Kumarasamy Manjula
Published: October 2021

Background

The demand for cataract surgery is expected to increase by 25% in the next 10 years as the result of our ageing population. A new pathway is being proposed to improve efficiency by utilising the new General Ophthalmic Services code 2.9 for community optometrists in Scotland for Cataract Referral Refinement and Consenting process. A pilot project has been undertaken at NHS Grampian enabling patients to be assessed and undergo surgery at a single visit to the Eye Outpatient Department.

Objectives

To determine the suitability of community cataract referrals for a one stop cataract surgery service and target areas for referral refinement.

Methods

300 consecutive cataract referrals were assessed for suitability for one stop cataract surgery, determined by the documentation of pertinent clinical findings. All suitable referrals were offered a telephone consultation to confirm suitability and those patients were subsequently offered on the day cataract surgery. A telephone led patient satisfaction survey was then completed.

Results

71 (24%) suitable patients were identified from vetting 300 referrals. 54 patients from this group were selected for one-stop service following telephone consultation. 51 patients subsequently attended for surgery. There was a 100% conversion rate to same day surgery and no intraoperative complications reported.

Conclusion

The waiting time was significantly reduced, by 30 weeks, for one-stop patients. Approximately one quarter of referrals were deemed suitable for a one-stop service. Many more patients may have been suitable for same day surgery but there was not sufficient information in their referrals to determine their suitability.
Decreased enrollment in breast cancer trials by histologic subtype: does invasive lobular carcinoma resist RECIST?
Authors: Abel Mary Kathryn , Melisko Michelle E. , Rugo Hope S. , Chien A. Jo , Diaz Italia , Levine Julia K. , Griffin Ann , McGuire Joseph , Esserman Laura J. , Borno Hala T. , Mukhtar Rita A.
Published: October 2021

Enrollment in metastatic breast cancer trials usually requires measurable lesions, but patients with invasive lobular carcinoma (ILC) tend to form diffuse disease. We found that the proportion of patients with metastatic ILC enrolled in clinical trials at our institution was significantly lower than that of patients with invasive ductal carcinoma (IDC). Possible links between requiring measurable disease and decreased enrollment of ILC patients require further study to ensure equitable trial access.
Resistance of SARS-CoV-2 variants to neutralization by convalescent plasma from early COVID-19 outbreak in Singapore
Authors: Wang Bei , Goh Yun Shan , Prince Tessa , Ngoh Eve Zi Xian , Salleh Siti Nazihah Mohd , Hor Pei Xiang , Loh Chiew Yee , Fong Siew Wai , Hartley Catherine , Tan Seow-Yen , Young Barnaby Edward , Leo Yee-Sin , Lye David C. , Maurer-Stroh Sebastian , Ng Lisa F. P. , Hiscox Julian A. , Renia Laurent , Wang Cheng-I
Published: October 2021

The rapid spreading of SARS-CoV-2 variants B.1.1.7 originated from the United Kingdom and B.1.351 from South Africa has contributed to the second wave of COVID-19 cases in the respective countries and also around the world. In this study, we employed advanced biochemical and virological methodologies to evaluate the impact of Spike mutations of these strains on the degree of protection afforded by humoral immune responses following natural infection of the ancestral SARS-CoV-2 strain during the early stages of the outbreak. We found that antibody-mediated neutralization activity was partially reduced for B.1.1.7 variant and significantly attenuated for the B.1.351 strain. We also found that mutations outside the receptor-binding domain (RBD) can strongly influence antibody binding and neutralization, cautioning the use of solely RBD mutations in evaluating vaccine efficacy. These findings highlight an urgent need to develop new SARS-CoV-2 vaccines that are not based exclusively on the ancestral SARS-CoV-2 Spike gene sequence.
A radio technosignature search towards Proxima Centauri resulting in a signal of interest
Authors: Smith Shane , Price Danny C. , Sheikh Sofia Z. , Czech Daniel J. , Croft Steve , DeBoer David , Gajjar Vishal , Isaacson Howard , Lacki Brian C. , Lebofsky Matt , MacMahon David H. E. , Ng Cherry , Perez Karen I. , Siemion Andrew P. V. , Webb Claire Isabel , Drew Jamie , Worden S. Pete , Zic Andrew
Published: October 2021

The detection of life beyond Earth is an ongoing scientific pursuit, with profound implications. One approach, known as the search for extraterrestrial intelligence (SETI), seeks to find engineered signals (‘technosignatures’) that indicate the existence of technologically capable life beyond Earth. Here, we report on the detection of a narrowband signal of interest at ~982 MHz, recorded during observations towards Proxima Centauri with the Parkes Murriyang radio telescope. This signal, BLC1, has characteristics broadly consistent with hypothesized technosignatures and is one of the most compelling candidates to date. Analysis of BLC1—which we ultimately attribute to being an unusual but locally generated form of interference—is provided in a companion paper. Nevertheless, our observations of Proxima Centauri are a particularly sensitive search for radio technosignatures towards a stellar target.
Long-term variation of 90Sr and 137Cs in environmental and food samples around Qinshan nuclear power plant, China
Authors: Cao Yiyao , Zhao Zhixin , Wang Peng , Yu Shunfei , Lai Zhongjun , Zhang Meibian , Gao Xiangjing , Zhao Yaoxian , Xuan Zhiqiang , Ren Hong , Zhang Dongxia , Lou Xiaoming
Published: October 2021

Environmental radioactivity monitoring in the surroundings of nuclear facilities is important to provide baseline data for effective detection in case of any radioactive release in the region. In this work, we report for the first time the long-term monitoring data of 137Cs and 90Sr in environmental and food samples around Qinshan nuclear power plant in 2012–2019. The distribution levels, temporal variations and source terms of 137Cs and 90Sr in the investigated samples were discussed. The annual effective dose (AED) for the local population from the ingestion of foods was also evaluated. Peak values of 90Sr and 137Cs concentrations and 137Cs/90Sr activity ratio were observed in total atmospheric deposition in 2016 and some water and food samples in the following years. This seems to be associated to an additional radioactive input, mostly likely from the operational release of a local facility. This demonstrates that 90Sr and 137Cs, especially the 137Cs/90Sr activity ratio, are sensitive indicators for detecting potential radioactive releases. Nevertheless, overall 90Sr and 137Cs activity concentrations measured during 2012–2019 in this work were at the background levels with average AED far below the internationally permissible limit and recommendation.
Risk factors and clinical analysis of peripherally inserted central catheter-related fungal colonization in premature infants
Authors: Zhang Lingping , Yang Liu , Dong Wenbin , Liu Xingling , Lei Xiaoping , Zhang Lianyu
Published: October 2021

We aimed to analyze the risk factors of positive peripherally inserted central catheter (PICC)-related fungal colonization in preterm infants. This retrospective study collected data from 2018 to 2020. The enrolled infants who underwent PICC insertion were born at < 32 weeks’ gestation or birth weight < 1500 g. The demographics, PICC-related characteristics, and treatment information were collected. Univariate and multivariate analyses were performed to investigate risk factors for PICC-related fungal colonization. The receiver operating characteristic (ROC) curve was used to determine the optimal cut-off values for the duration of antibiotics and parenteral nutrition. In total, 124 premature infants underwent PICC insertion. Among them, 19 patients had positive results of fungi on the PICC tips. The duration of antibiotics (odds ratio [OR] 1.16, 95% confidence interval [CI] 1.02–1.31), parenteral nutrition infusion (OR 1.27, 95% CI 1.05–1.54), and postnatal glucocorticoid exposure (OR 9.48, 95% CI 1.06–84.98) were independent risk factors for fungal colonization in PICCs. The ROC curves showed that the risk increased after 15 days of antibiotic use and 28 days of parenteral nutrition infusion. Appropriate clinical management should be used to prevent fungal colonization and fungemia.
Antidiabetic effect of gemigliptin: a systematic review and meta-analysis of randomized controlled trials with Bayesian inference through a quality management system
Authors: Oh Hojin , Nguyen Hai Duc , Yoon In Mo , Ahn Byung-Ryong , Kim Min-Sun
Published: October 2021

Gemigliptin is one of the latest dipeptidyl peptidase-4 inhibitors developed by LG Life Sciences. Since the early 2000s, several randomized controlled trials (RCTs) of gemigliptin have been conducted. However, no study has directly compared its antidiabetic effects through a systematic review and meta-analysis. Therefore, in this study, we performed a systematic review and meta-analysis on RCTs. In particular, a subsequent meta-analysis was performed using Bayesian inference, and an updated quality management system model was integrated throughout our study. The mean differences and 95% confidence intervals for glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), homeostatic model assessment beta cell function (HOMA-β), and low-density lipoprotein (LDL) were evaluated for the efficacy outcomes of gemigliptin as compared to those of placebo and other oral antidiabetic drugs (OADs). In conclusion, we found that gemigliptin was superior to placebo and comparable to other OADs in terms of the effect on HbA1c, FPG, HOMA-β, and LDL. Further, gemigliptin was more effective than other OADs in HbA1c and HOMA-β in Bayesian inference analysis and statistically significant to other OADs in HbA1c and HOMA-β in sensitivity analysis excluding metformin. However, to confirm the results, more studies need to be analysed and the minimum clinically important difference must be applied.
Prediction of fall risk among community-dwelling older adults using a wearable system
Authors: Lockhart Thurmon E. , Soangra Rahul , Yoon Hyunsoo , Wu Teresa , Frames Christopher W. , Weaver Raven , Roberto Karen A.
Published: October 2021

Falls are among the most common cause of decreased mobility and independence in older adults and rank as one of the most severe public health problems with frequent fatal consequences. In the present study, gait characteristics from 171 community-dwelling older adults were evaluated to determine their predictive ability for future falls using a wearable system. Participants wore a wearable sensor (inertial measurement unit, IMU) affixed to the sternum and performed a 10-m walking test. Measures of gait variability, complexity, and smoothness were extracted from each participant, and prospective fall incidence was evaluated over the following 6-months. Gait parameters were refined to better represent features for a random forest classifier for the fall-risk classification utilizing three experiments. The results show that the best-trained model for faller classification used both linear and nonlinear gait parameters and achieved an overall 81.6 ± 0.7% accuracy, 86.7 ± 0.5% sensitivity, 80.3 ± 0.2% specificity in the blind test. These findings augment the wearable sensor's potential as an ambulatory fall risk identification tool in community-dwelling settings. Furthermore, they highlight the importance of gait features that rely less on event detection methods, and more on time series analysis techniques. Fall prevention is a critical component in older individuals’ healthcare, and simple models based on gait-related tasks and a wearable IMU sensor can determine the risk of future falls.
Lattice dynamics in CePd2Al2 and LaPd2Al2
Authors: Doležal Petr , Cejpek Petr , Tsutsui Satoshi , Kaneko Koji , Legut Dominik , Carva Karel , Javorský Pavel
Published: October 2021

The interaction between phonons and 4f electrons, which is forming a new quantum state (quasi-bound state) beyond Born-Oppenheimer approximation, is very prominent and lattice dynamics plays here a key role. There is only a small number of compounds in which the experimental observation suggest such a scenario. One of these compounds is CePd2Al2. Here the study of phonon dispersion curves of (Ce,La)Pd2Al2 at 1.5, 7.5, 80 and 300 K is presented. The inelastic X-ray scattering technique was used for mapping the phonon modes at X and Z points as well as in Λ and Δ directions, where the symmetry analysis of phonon modes was performed. The measured spectra are compared with the theoretical calculation, showing very good agreement. The measurements were performed in several Brillouin zones allowing the reconstruction of phonon dispersion curves. The results are discussed with respect to the magneto-elastic interaction and are compared with other cerium compounds. The phonon mode symmetry A1g was found to be unaffected by the interaction, which is in contrast to previous assumptions.
The gut commensal fungus, Candida parapsilosis, promotes high fat-diet induced obesity in mice
Authors: Sun Shanshan , Sun Li , Wang Kai , Qiao Shanshan , Zhao Xinyue , Hu Xiaomin , Chen Wei , Zhang Shuyang , Li Hantian , Dai Huanqin , Liu Hongwei
Published: October 2021

Gut fungi is known to play many important roles in human health regulations. Herein, we investigate the anti-obesity efficacy of the antifungal antibiotics (amphotericin B, fluconazole and 5-fluorocytosine) in the high fat diet-fed (HFD) mice. Supplementation of amphotericin B or fluconazole in water can effectively inhibit obesity and its related disorders, whereas 5-fluorocytosine exhibit little effects. The gut fungus Candida parapsilosis is identified as a key commensal fungus related to the diet-induced obesity by the culture-dependent method and the inoculation assay with C. parapsilosis in the fungi-free mice. In addition, the increase of free fatty acids in the gut due to the production of fungal lipases from C. parapsilosis is confirmed as one mechanism by which C. parapsilosis promotes obesity. The current study demonstrates the gut C. parapsilosis as a causal fungus for the development of diet-induced obesity in mice and highlights the therapeutic strategy targeting the gut fungi.
A thiocarbonate-caged fluorescent probe for specific visualization of peroxynitrite in living cells and zebrafish
Authors: Xin Fangyun , Zhao Jiwei , Shu Wei , Zhang Xiaoling , Luo Xixian , Tian Ying , Xing Mingming , Wang Hong , Peng Yong , Tian Yong
Published: October 2021

A novel fluorescent probe NA-ONOO was designed and constructed for in vitro and in vivo ONOO− imaging by virtue of an upgraded ONOO−-specific recognition group.
DO-SRS imaging of metabolic dynamics in aging Drosophila
Authors: Li Yajuan , Zhang Wenxu , Fung Anthony A. , Shi Lingyan
Published: October 2021

Emerging studies have shown that lipid metabolism plays an important role in aging.
Relationship between crystal shape and unit cell shape: crystal shape modification via co-crystallization toward SXRD-suitable crystals
Authors: Okayasu Misaki , Kikkawa Shoko , Hikawa Hidemasa , Azumaya Isao
Published: October 2021

The relationships between the shape and cell parameters were investigated using 131 crystals of secondary aromatic sulfonamides. And, 11 sulfonamides isolated as oils, amorphous, or needle crystals were co-crystallized to obtain block-like crystals.
How DNA affects the hyperthermophilic protein Ape10b2 for oligomerization: an investigation using multiple short molecular dynamics simulations
Authors: Zhang Xue , Zheng Qingchuan
Published: October 2021

Ape10b2 can stabilize DNA at high temperature and DNA disturbance of the protein is beneficial for oligomerization.
Surface functionalization of MXenes
Authors: Mozafari Mohammad , Soroush Masoud
Published: October 2021

Diverse applications have been reported for MXenes owing to their extraordinary physicochemical properties and various chemical compositions.
Fe2O3/rGO/CNT composite sulfur hosts with physical and chemical dual-encapsulation for high performance lithium–sulfur batteries
Authors: Dong Wei , Meng Lingqiang , Zhao Meina , Yang Fang , Shen Ding , Hong Xiaodong , Tang Shuwei , Sun Wen , Yang Shaobin
Published: October 2021

A sulfur host material of a Fe2O3/rGO/CNT fluffy composite with Fe2O3 and CNTs being dispersed between the rGO interlayers has been prepared by a hydrothermal reaction. The initial specific capacity of Fe2O3/rGO/CNT/S at 2C is 899 mA h g−1.
Deep learning to analyse microscopy images
Authors: Jacquemet Guillaume
Published: October 2021

Artificial intelligence (AI)-powered algorithms are now influencing many aspects of our day-to-day life, from providing movies/music recommendations to controlling self-driving cars. These algorithms are also increasingly used in the lab to aid biomedical research. In particular, the ability to analyse and process images using AI is slowly revolutionizing the quality and quantity of data we collect from microscopy images. In fact, AI-based algorithms can now be applied to perform virtually any high-performance image analysis tasks such as classifying images, detecting and segmenting objects, aligning images or improving image quality by removing noise or increasing image resolution. This short feature article briefly underlies the principles behind using AI algorithms to analyse microscopy images with a specific focus on segmentation and denoising.
Word Fluency Test Performance in Primary Progressive Aphasia and Primary Progressive Apraxia of Speech
Authors: Scheffel Lucia , Duffy Joseph R. , Strand Edythe A. , Josephs Keith A.
Published: October 2021

Purpose

This study compared performance on three-word fluency measures among individuals with primary progressive aphasia (PPA) and primary progressive apraxia of speech (PPAOS), and examined the relationship between word fluency and other measures of language and speech.

Method

This study included 106 adults with PPA and 30 adults with PPAOS. PPA participants were divided into three clinical subgroups: semantic (svPPA), logopenic (lvPPA), and nonfluent/agrammatic with or without apraxia of speech (nfPPA). Category fluency, letter fluency, and action/verb fluency tasks were administered to all participants.

Results

The four clinical groups performed abnormally on the word fluency measures, although not to a degree that represented high sensitivity to their PPA or PPAOS diagnosis. All PPA subgroups produced fewer words compared to individuals with PPAOS on all word fluency measures. Moderate correlations were found between word fluency and aphasia severity and naming performance in some of the clinical groups.

Conclusions

Word fluency measures are often challenging for individuals with PPA and PPAOS, but they are not of equal difficulty, with letter fluency being the most difficult. Differences among word fluency tests also vary to some degree as a function of the clinical group in question, with least impairment in PPAOS. However, the findings of this study do not support statistically significant differences in word fluency task performance among the PPA subgroups. Correlations suggest that word fluency performance in PPA is at least partly related to aphasia severity.
A methodological approach for a home occupants centred web tool to support buildings energy retrofitting process
Authors: Pili Stefano , Poggi Francesca , Frau Caterina
Published: October 2021

This paper presents a methodological approach to develop a user-oriented web tool to support the early stage of the decision making process for energy retrofitting of residential real estates. The tool mixes a simple analytical Urban Building Energy Model (UBEM) to user-oriented feedback interfaces to simulate the retrofitting potential of the residential units. The AUREE tool will be based on a Web – GIS GeoBlog portal with customized interfaces aimed to share the knowledge on urban building heritage and promote participation of stakeholders of the urban community. There are many literature exempla of guidelines or quality protocols on the topic of energy efficiency specified to particular types of buildings or focused on a territorial area, but these are generally not integrated into a geographically based tool. Moreover, the AUREE methodology aims to set interfaces that could use the portal users’ feedback to update the content of the portal itself. After touch on the theoretical context, a summary of the AUREE project is presented, and then the paper focuses on the structures of algorithms and tools adopted on the residential users’ interfaces. The interface mixes the results of an engineering Urban Building Energy Model based on local archetypal approach and standard energy calculation (series UNI 11300 - TS), with participative data provided via user-interactive interfaces to obtain customized retrofitting scenarios and suggestions. At the end of the paper, the main critical aspects and the further step of the research project are pointed
Towards Zero Energy Districts developments base on bioclimatic strategies: A Numerical Study in a Developing Country
Authors: De León Lissette , Chen Austin Miguel , Carpino Cristina , Mora Dafni
Published: October 2021

The need for more efficient buildings to contribute to more sustainable development has led to the establishment of targets in different countries. European countries have presented energy plans to respond to the guidelines of achieving near-zero energy buildings (nZEB). The concept can be defined at the urban scale (nZED), being a delimited part of a city with high energy efficiency and using renewable energies within its boundaries. This research aims to carry out a numerical study in a residential development in Panama, based on a proposal to redesign it, but using bioclimatic strategies and implementing photovoltaic technology. Thus, to evaluate the feasibility of nZED in the region and to function as a preliminary study to implement regulations of this type in the country. The results indicate that the indoor comfort conditions of each residential building should be evaluated in greater depth, and energy savings of 40% were obtained by implementing the recommended bioclimatic strategies and becoming independent of air conditioning equipment. In addition, photovoltaic generation outstrips demand, making the development net energy positive.
Recognition of two-phase flow pattern inside evaporator tubes
Authors: Amoresano Amedeo , Iodice Paolo , Langella Giuseppe , Niola Vincenzo , Quaremba Giuseppe
Published: October 2021

The convective heat exchange mechanism in two-phase regime, can allow high exchange coefficients, as long as particular conditions are respected, in terms of vapor quality. In evaporator tubes this problem is particularly important as a deviation from the optimal flow conditions can drastically drop the efficiency of the heat exchange. This work describes an innovative methodology for identifying the different two-phase flow regimes in evaporator pipes, through the processing of the vibrational data acquired on the pipe itself. An experimental apparatus with transparent pipes has been built up to recognize flow patterns by a fast image acquisition camera. Images have been associated to vibration data acquired on pipes by accelerometer. The analysis of frequency spectrum, led to first interesting results thus it is possible to distinguish between “no bubbles” regimes and different “bubbles” regimes. A wide test campaign has been realized on vertical and horizontal pipes, simulating steam bubbles with nitrogen bubbles, reproducing the main flow patterns. The paper demonstrates the possibility to design smart and non-intrusive sensor to be applied on evaporated tubes for the recognizing of anomalous thermal flow condition and sets the stage for future engineering work.
Application of modelling approaches of twin-screw compressors: thermodynamic investigation and reduced-order model identification
Authors: Di Mattia Edoardo , Gambarotta Agostino , Morini Mirko , Saletti Costanza
Published: October 2021

Refrigeration is an essential part of the food chain. It is used in all stages of the chain, from industrial food processing to final consumption at home. In these processes, mechanical refrigeration technologies are employed, where compressors increase gas pressure from evaporation to condensation. In industrial refrigeration systems, twin-screw compressors represent the most widely used technology. A detailed mathematical model of a twin-screw compressor has been developed in Simulink® using differential equations for energy and mass balances to simulate the compression cycle that includes suction, compression and discharge phases. Gas pressure and enthalpy can be calculated as time functions during the cycle. However, the computational times obtained limit the possibility to extend the use of the model in the development of control strategies for the whole refrigeration plant in its real operating conditions. Therefore, the detailed model has been used to train a simplified model developed in Matlab®: the simulated mass flow rate, shaft power and the fluid discharge temperature have been employed to identify several geometrical and thermodynamic parameters of the simplified model. The latter relies on non-linear algebraic equations and, thus, requires a very short computational time. A limited performance dataset has been used to train the model, and a different dataset to test it: the results of the models have been compared, and small errors in mass flow rate, shaft power and fluid discharge temperature have been observed.
Numerical Modelling and Experimental Validation of Twin-Screw Pumps Based on Computational Fluid Dynamics using SCORG®and SIMERICS MP+®
Authors: Borriello Pasquale , Frosina Emma , Senatore Adolfo , Monterosso Federico
Published: October 2021

This paper presents a methodology for simulating screw pumps using a 3D-CFD transient approach. It is known in literature that the advantages of screw pumps in noise emission, reliability, and their capacity to work with any kind of fluid make their applications interesting for many fields. Increasing demands for high-performance screw pumps require a deep understanding of the flow field inside the machine. The investigation is performed by use of a 3D computational fluid dynamics analysis based on a single-domain structured moving mesh obtained by novel grid generation procedure through the commercial software SCORG. The real-time mass flow rate, rotor torque, pressure distribution, velocity field, and other performance indicators including the indicated power were obtained from numerical simulations performed in the SimericsMP+ environment. The performance curves of the numerical model were produced for variable rotation speeds and discharge pressures and compared with experimental data with high accuracy. The pressure distribution in the screw groove is relatively uniform, the screw clearance and the meshing area pressure are different from the screw groove pressure distribution. The results demonstrate that the speed does not have a considerable effect on the pressure field. At last, the numerical model was validated by comparing the numerical results with the measured performance obtained in the experimental test rig through the comprehensive experiment performed for a set of discharge pressures and rotational speeds. The model has shown to predict pressure variation and flow rate with good accuracy.
The application of the EN ISO 52016 standard and its Italian National Annex to assess the heating and cooling needs of a reference office building
Authors: Bianco Mauthe Degerfeld Franz , Ballarini Ilaria , De Luca Giovanna , Corrado Vincenzo
Published: October 2021

The EN ISO 52016-1 standard presents a new simplified dynamic calculation procedure, whose aim is to provide an accurate energy performance assessment without excessively increasing the number of data required. The Italian National Annex to EN ISO 52016-1, currently under development, provides some improvements to the hourly calculation method; despite many works can be found in literature on the hourly model of EN ISO 52016-1, the National Annexes application has not been sufficiently analysed yet. The aim of the present work is to assess the main improvements introduced by the Italian National Annex and to compare the main results, in terms of energy need for space heating and cooling. To this purpose, an existing building representative of the Italian office building stock in Northern Italy was selected as a case study. The energy simulations were carried out considering both continuous and reduced operation of the HVAC systems. The options specified in the Italian National Annex were firstly applied one by one, and then all together. The variation of the energy need compared to the international base procedure is finally quantified. For the premises and the scope above discussed, the present work is intended to enhance the standardisation activity towards the adoption of more accurate and trustable calculation methods of the building energy performance.
Use of Land Surface Temperature Estimation with Geographical Information Tools for Validation of Numerical Microclimate Studies at Urban Scale
Authors: Bustamante Mileyka , Mora Dafni , Chen Austin Miguel
Published: October 2021

For this study, different approaches found in the literature to obtain the Land Surface Temperature (LST) were evaluated through Geographic Information tools, to validate the temperature results obtained from dynamic simulations at urban scale with the Envi-met software. Here, the case study is an urban section of the Historic center of Panama City named Casco Antiguo. From the dynamic simulation results, the surface temperature was analyzed for March at 15:00. Concerning the results obtained for March, the Online Global Land Surface Temperature Estimation tool provided the best characteristics when validating the data obtained with Envi-met. It was found that the Landsat 7 images, applying the emissivity method ASTER and NDVI, provided data more stable and closer to the ones we wanted to validate.
Evaluation of a novel strategy, based in Coolant Flow Rate Control, for avoiding Knock in a SI engine
Authors: Falbo Luigi
Published: October 2021

An experimental study is carried out for investigating the possibility to limit knock occurrence on a SI engine by proper engine thermal management. The control of the wall temperature is realized by means of an electrically driven water pump. The coolant flow rate can be varied regardless of the engine speed. Preliminarily, an experimental campaign aimed at evaluating the effects of the coolant flow rate on the in-cylinder pressure fluctuations, under steady state engine operation, namely WOT@1500 rpm, is presented. In the experiments, the spark advance and the equivalence ratio are controlled by the ECU according to the production engine map and the coolant flow rate is varied from 1500 up to 4500 dm3/h. In a subsequent set of tests, a variation on spark advance is operated and, for each value of the spark advance, different coolant flow rates are enforced with the aim of evaluating the possibility to increase the spark advance as close as possible to the maximum brake torque condition and of mitigating knock occurrence with increased coolant flow rates. The benefits in terms of fuel economy and increase engine performance, in comparison to the traditional approaches for knock mitigation, are evaluated.
Hydrogen refueling station cost model applied to five real case studies for fuel cell buses
Authors: Caponi Roberta , Monforti Ferrario Andrea , Del Zotto Luca , Bocci Enrico
Published: October 2021

Hydrogen Refueling Stations (HRS) are a key infrastructure to the successful deployment of hydrogen mobility. Their cost-effectiveness will represent an increasingly crucial issue considering the foreseen growth of vehicle fleets, from few captive fleets to large-scale penetration of hydrogen vehicles. In this context a detailed, component-oriented cost model is important to assess HRS costs for different design concepts, layout schemes and possible customizations, respect to aggregate tools which are mostly available in literature. In this work an improved version of a previously developed component-oriented, scale-sensitive HRS cost model is applied to 5 different European HRS developed within the 3Emotion project with different refueling capacities (kgH2/day), hydrogen supply schemes (in-situ production or delivery), storage volumes and pressures and operational strategies. The model output allows to assess the upfront investment cost (CAPEX), the annual operational cost (OPEX) and the Levelized Cost of Hydrogen (LCOH) at the dispenser and identify the most crucial cost components. The results for the five analyzed HRS sites show an LCOH at the nozzle of around 8-9 €/kg for delivery based HRSs, which are mainly dominated by the H2 retail price and transport service price and around 11-12 €/kg for on-site producing HRS, for which the electrolyzer CAPEX and electricity price plays a key role in the cost structure. The compression, storage, and dispensing sections account for between 1-3 €/kg according to the specific design & performance requirements of the HRS. The total LCOH values are comparable with literature, standard market prices for similar scale HRSs and with the 3Emotion project targets.
Jet ignition in small two-stroke engines: an experimental survey on benefits and challenges
Authors: Bosi Lorenzo , Ciampolini Marco , Raspanti Sandro , Romani Luca , Ferrara Giovanni
Published: October 2021

Increasingly stringent policy on carbon dioxide have proved to be a severe constraint on the design of light two-stroke (2S) engines. The enhancement of efficiency is claimed to be the main target to make these devices compliant with future regulations. Low-Pressure Direct Injection (LPDI) was found to be effective in the reduction of fuel short circuit, thus improving efficiency and mitigating pollution. Innovative combustion technologies are required to exploit further the fuel potential. Jet Ignition (JI), i.e., ignition provided by means of hot turbulent jets, was found to improve the fuel ignition process, leading to a faster and more uniform combustion. Several benefits are shown in over forty years of Literature, from the higher performance to wider flammability limits. However, few studies have been performed on small 2S engines, for which only full-load data are available. This paper aims at experimentally evaluating benefits and challenges of adopting the JI technology on light 2S LPDI engines at both full- and low- load operation. Different configurations of passive prechambers have been investigated in terms of indicated cycle, brake efficiency and cycle-to-cycle variation. A sensitivity analysis on the spark timing was performed to fine-tune the combustion process. Results show the adequacy of the JI for use in devices operating close to full torque, like garden tools; however, issues related to the excessive amount of residual gas or to the rapid pressure decrease during the expansion phase were highlighted. Different solutions for solving these challenges are proposed.
LPT (Local Public Transport) electric buses: innovative solutions to reduce the energy absorption of auxiliaries
Authors: Orecchini Fabio , Santiangeli Adriano , Zuccari Fabrizio , Ortenzi Fernando , Genovese Antonino , Valentini Maria Pia
Published: October 2021

The focus of the study is the analysis and sizing of the air conditioning system on board the vehicle which operates in thermal transient for the duration of the typical mission, using “fan coil” type air conditioning devices powered by a hot or cold heat vector fluid loaded into “electro-thermal” charging station and the related ground cogeneration plant (at the BUS terminus). For winter air conditioning, it was assumed that a heat transfer fluid at a temperature of 90 ° C could be stored on board. This value allows the use of water as a heat transfer fluid without pressurizing the systems, minimizing costs and supply problems, and is compatible with the characteristics of ICE cogeneration systems. For summer air conditioning, it was assumed that ice or fluid at a temperature of -20 ° C could be loaded. Also in this case it was decided to operate with a common fluid, such as a solution of water and salt (e.g. calcium chloride CaCl2). A comparative analysis of two solutions was carried out: the first involves the standard solution with BUS air conditioning system with heat pump powered by traction batteries charged by the grid and the second one analyzes the use of a high temperature Fuel Cell in a trigenerative configuration with refrigeration unit absorption fueled by the fumes of the FC. The trigeneration plant produces 100 kW of electricity via SOFC (Solid Oxide Fuel Cell) and, through an exchanger, water at 95 ° C which is stored on board the BUS for winter heating and feeds an absorption refrigeration machine that produces fluid at a temperature of -20 ° C for summer conditioning. For the two solutions, the savings of non-renewable primary energy and the reduction of GHG emissions compared to the standard solution (recharging the electric BUS from the network with on-board air conditioning powered by the traction batteries) are calculated through a WTW analysis. Consumption and emissions of electric powertrains, potentially for consumption and zero emissions, are closely linked to the methods of production and distribution of electricity.
Non-catalytic NOx reduction for marine Diesel engine: an experimental approach
Authors: Galletti Anna Maria Raspolli , Frigo Stefano , Antonelli Marco , Pasini Gianluca , Bertetti Paolo , Tocchi Federico
Published: October 2021

Recent legislation concerning air pollutant emissions from ships (Tier III) has considerably decreased NOx emission limits for recreational ships with less than 500 gross tonnages and greater than 24 m load line length (LLL), the so-called “large yachts”. For these yachts, which adopt multiple Diesel engines with maximum power ranging from 800 to 2000 kW, the new NOx limit is less than 2 g/kWh. To satisfy that limit, engine makers suggest the adoption of a classic SCR system with urea injection but this methodology, in addition to requiring a large space for installation, does not seem so appropriate for diesel engines of large yachts that normally operate at low power with exhaust temperatures often well below 300 °C, therefore not sufficient to allow the correct functioning of the SCR. The aforementioned circumstances have prompted Sanlorenzo Spa (La Spezia – Italy), one of the world’s leading companies in the production of pleasure boats, to collaborate with the University of Pisa in the study of alternative solutions to SCR systems. Recently there is a great interest in innovative NOx abatement systems, based on the possibility of absorbing NOx molecules into seawater through the utilization of appropriate aqueous solutions containing targeted saline oxidizing agents. The present study describes the first results of a research program aimed to identify, from one side, the best saline oxidizing agent for an aqueous NOx abatement and, from the other, the best washing methodology compatible with the propulsion layouts usually adopted on yachts. In the engine testing laboratories of the Department of Energy, Systems, Territory and Construction Engineering (DESTeC) of the University of Pisa, an experimental apparatus has been created to reproduce the real conditions of underwater engine exhausting. This device was combined with a small 1.2 L direct injection diesel engine. The first results showed a reduction of the NOx emissions of about 27% by using a gas washing with wet scrubber, followed by bubbling in water, using 0.2 molar NaClO saline solutions.
Numerical comparison between conventional and interdigitated flow fields in Proton Exchange Membrane Fuel Cells (PEMFCs)
Authors: Corda Giuseppe , d’Adamo Alessandro , Riccardi Matteo
Published: October 2021

The recent trend towards the decarbonization of the energy system has renewed the scientific community's interest in fuel cells. These devices have the potential to eliminate, or greatly reduce, the production of greenhouse gases. Polymeric Electrolyte Membrane Fuel Cells (PEMFC) are among the most promising technologies in this regard, being suited for various applications in stationary power plants, vehicles, and portable power devices. The critical issues in PEMFC are the limitation of oxygen transport through the air cathode and water management at high current density operation, which could be largely limited by modifying the design of the reactant supplier channels. In this paper, a three-dimensional CFD approach is used to compare straight and interdigitated flow fields, focusing on the increased current density and improved water management in the diffusion and catalyst layers for the interdigitated design. The simulation results show that the fluid is forced to flow through the porous layers, promoting a convection-type transport, leading to better water removal from the porous layers as well as to increased transport rates of reactants/products to/from the catalyst layers.

This leads to reduced concentration overpotentials, and it shows the potential of simulation-driven design for high energy density PEMFC systems.