bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk factors for intradialytic decline in cerebral perfusion and impaired cerebral autoregulation in adults on hemodialysis
Authors: Wolfgram Dawn F. , Novotny Julia , Goodman Max J. , Visotcky Alexis , Laud Purushottam , Barnes Jill N.
Published: July 2021

Introduction

Hemodialysis (HD) patients have significant burden of cerebral ischemic pathology noted on brain imaging. These ischemic type lesions maybe due to cerebral hypoperfusion that may be occurring during blood pressure (BP) fluctuations commonly noted during HD sessions. We evaluated changes in cerebral perfusion and measured an index of cerebral autoregulation (CA index) during HD to identify potential risk factors for intradialytic decline in cerebral perfusion and impaired cerebral autoregulation.

Methods

In this cross‐sectional study, we included HD patients age 50 years or older receiving conventional in‐center HD. We measured cerebral perfusion during HD, using cerebral oximetry, and calculated the correlation between cerebral perfusion and BP during HD as an index of CA. We measured the association between potential risk factors for intradialytic decline in cerebral perfusion and CA index.

Findings

We included 32 participants and 118 HD sessions in our analysis. The mean ± SD decline in cerebral oxygen saturation during HD was 6.5% ± 2.9% with a relative decline from baseline values of 9.2% ± 4.4%. Greater drop in systolic BP (SBP) during HD was associated with decline in cerebral oxygen saturation, p = 0.02. Impaired CA index was noted in 37.3% of HD sessions. Having diabetes and >20 mmHg drop in SBP during HD were associated with increased (worse) CA index with an increase of 0.24 95%CI [0.06, 0.41] for diabetes and increase of 0.43 95%CI [0.27, 0.56] for a >20 mmHg drop in SBP during HD.

Discussion

Cerebral perfusion can decline during HD and is associated with changes in systemic BP. This may be due to impaired cerebral autoregulation in HD patients. Risk factors for worse CA index include diabetes and >20 mmHg drop in SBP during HD. This study highlights the risk of intradialytic decline in cerebral perfusion and impaired cerebral autoregulation in HD patients.
Efficacy of erythritol powder air‐polishing in active and supportive periodontal therapy: A systematic review and meta‐analysis
Authors: Abdulbaqi Hayder R. , Shaikh Muhammad Saad , Abdulkareem Ali A. , Zafar Muhammad S. , Gul Sarhang S. , Sha Aram M.
Published: July 2021

Objective

This systematic review aimed to analyse available evidence to answer two focused questions about the efficacy of erythritol powder air‐polishing (EPAP) (i) as an adjunctive during active periodontal therapy (APT) and (ii) as an alternative to hand/ultrasonic instrumentation during supportive periodontal therapy (SPT). Additionally, microbiological outcomes and patient's comfort/perceptions were assessed as secondary outcomes.

Methods

PubMed, Cochrane and Medline were searched for relevant articles published before February 2021 following PRISMA guidelines. The search was conducted by three independent reviewers, and the agreement was measured by Cohen's kappa score. Out of 1043 articles, eight randomized clinical trials were selected for systematic review and quantitative synthesis. Only periodontal parameters, such as clinical attachment level (CAL), probing pocket depth (PPD) and bleeding on probing (BoP), showed homogeneity and, thus, were selected for meta‐analysis.

Results

The improvement in PPD and BoP scores after using EPAP was comparable with hand/ultrasonic instrumentation during both APT and SPT. Significant CAL gain was achieved with EPAP during APT (0.16 mm, p < 0.02) compared with hand/ultrasonic instrumentation at the end point, whereas non‐significant CAL gain was achieved during SPT. No differences were observed regarding microbiological outcomes between the two treatment modalities. However, EPAP inflicted less pain and was better perceived by the patients.

Conclusion

Erythritol powder air‐polishing can substitute hand/ultrasonic instrumentation for SPT, and CAL gain is significantly improved when EPAP is used as an adjunct during APT. For microbiological outcomes, no significant differences were observed between the two approaches; however, EPAP was better tolerated by the patients than hand/ultrasonic instrumentation.

Clinical relevance

Erythritol powder air‐polishing can be used as an adjunct during APT and as an alternative to conventional mechanical debridement during SPT.
Feasibility, safety and outcomes of ambulation within 2 h postoperatively in patients with lung cancer undergoing thoracoscopic surgery
Authors: Liu Tingting , Feng Jing , Ge Ling , Jin Fengxia , Zhou Chao , Liu Xiaoxin
Published: July 2021

Aims

The aims of this study were to evaluate the safety, feasibility and outcomes of ambulation within 2 h after thoracoscopic surgery in patients with lung cancer.

Background

There are no consensus guidelines on the ideal time for early ambulation following thoracic surgery, although enhanced recovery programmes have been proposed since years.

Methods

This non‐randomized, concurrent‐control study was conducted on patients who underwent thoracoscopic surgery between October 2020 and February 2021. Participants were assigned to either the observation group (ambulation within 2 h of extubation) or the control group (ambulation on the first postoperative day).

Results

Of the 325 patients who were eligible, 227 were included in the study. Eighty‐three per cent of patients were able to walk any distance within 2 h of extubation, and no adverse events occurred in patients. The length of hospital stay and time to first postoperative flatus were significantly shorter in the observation group than in the control group. There were no differences in the occurrence of postoperative complications and orthostatic hypotension, readmission rate and 6‐min walk distance at discharge.

Conclusion

Ambulation within 2 h of extubation was safe and feasible and could lead to better recovery in patients with lung cancer undergoing thoracoscopic surgery.
Fair play? Sex‐, age‐, and job‐related correlates of performance in a computer‐based simulation game
Authors: Melchers Klaus G. , Basch Johannes M.
Published: July 2021

Gamified and game‐based assessments (GBAs) are increasingly used for personnel selection but there are concerns that males and younger applicants have an advantage in these assessments. However, hardly any research has addressed whether sex and age are related to GBA performance. Similarly, the criterion‐related validity of GBAs is also not sufficiently confirmed. Therefore, we analyzed archival data from a high‐stakes setting in which applicants completed a computer‐based simulation game targeting complex problem solving. The analyses confirmed expectations for the present simulation game of better performance for males than for females and for younger than for older applicants. However, the effect sizes were small. Furthermore, performance in the current simulation game correlated with job‐related performance as measured in an assessment center.
Excellent ferroelectric and pyroelectric performance of rhombohedral Mn‐doped PIMNT thin films with (111) orientation
Authors: Huang Xiaoli , Tang Yanxue , Wang Feifei , Ming Leung Chung , Zhao Xiangyong , Qin Xiaomei , Wang Tao , Duan Zhihua , Wu Yanhui , Wang Jiasheng , Shi Wangzhou
Published: July 2021

Mn‐doped 0.36Pb(In1/2Nb1/2)O3–0.36Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 [Mn‐PIMNT(36/36/28)] thin films were fabricated by pulsed laser deposition. The microstructures and ferroelectric, piezoelectric, dielectric, pyroelectric properties were investigated. The films exhibited a (111) orientation as well as a uniform and dense surface. The Raman spectra revealed that the films showed a rhombohedral phase at room temperature, rhombohedral to tetragonal, and tetragonal to paraelectric phase transitions near 150℃ and 250℃, respectively. Furthermore, the films exhibited a high remnant polarization (Pr) of 51.3 μC cm−2, a coercive field (EC) of 3.14 kV mm−1, a high normalized piezoelectric strain coefficient () up to 47 pm V−1, a pyroelectric coefficient (p) up to 8.5 × 10−4 C m−2 K−1, and dielectric constant (εr) of 2824, as well as excellent dielectric tunability of 89% at room temperature. The excellent ferroelectric and pyroelectric properties combined with high Curie point indicate that the Mn‐PIMNT(36/36/28) films are a potential candidate for ferroelectric and pyroelectric devices.
Peripheral thermometry: Agreement between non‐touch infrared versus traditional modes in an adult population
Authors: Sweeting Penelope , Murphy Minakshi , Geraghty Sadie , Duddle Maree
Published: July 2021

Aim

To test whether infrared non‐touch forehead thermometry (FNTT) obtains comparable temperature readings in adults compared with common, non‐invasive thermometry methods such as axillary (DAT), oral (DOT) and infrared tympanic (ITT).

Design

A prospective, repeated‐measures comparative diagnostic test study design was used for this study.

Methods

Data were collected from a convenience sample of 169 nursing students over 3 months (March 2019 to May 2019). Participants had their temperature measured once with each of the four thermometers. Agreement between thermometers was assessed using repeated‐measures analysis of variance with Bonferroni post hoc testing.

Results/findings

One hundred and sixty‐one participants were included in the final analysis. A repeated‐measures ANOVA showed statistically significant differences between the four thermometer temperature readings. Post hoc pairwise comparisons with Bonferroni adjustment revealed infrared non‐touch forehead thermometry demonstrated statistically significant higher mean temperatures compared with digital oral thermometry MD = 0.466℃ (95% CI, 0.357–0.576, p < .001) and digital axillary thermometry MD = 0.897℃ (95% CI, 0.752–1.043, p < .001), but not with infrared tympanic MD = 0.069℃ (95% CI, −0.025–0.162, p = .307).

Conclusions

This study found that infrared non‐touch forehead thermometry consistently produced higher temperature readings in adults compared with other common forms of peripheral thermometry. Caution should be taken when using forehead non‐touch thermometer readings interchangeably with digital oral and digital axillary readings unless corrections for bias are made. More research is needed into whether infrared non‐touch forehead thermometry and infrared tympanic could be used interchangeably.

Impact statement

This study aimed to address whether non‐touch forehead could be used interchangeably with other common forms of non‐invasive thermometry. Our result revealed inconsistencies in temperature readings between the different thermometers. Consequently, healthcare professionals should exercise caution when monitoring temperature trends where readings have been taken by different types of peripheral thermometers. This study could impact healthcare clinicians responsible for the monitoring and recording of peripheral temperatures.
The emerging roles of long non‐coding RNAs in polyglutamine diseases
Authors: Dong Xiaoyu , Cong Shuyan
Published: July 2021

Polyglutamine (polyQ) diseases are characterized by trinucleotide repeat amplifications within genes, thus resulting in the formation of polyQ peptides, selective neuronal degeneration and possibly death due to neurodegenerative diseases (NDDs). Long non‐coding RNAs (lncRNAs), which exceed 200 nucleotides in length, have been shown to play important roles in several pathological processes of NDDs, including polyQ diseases. Some lncRNAs have been consistently identified to be specific to polyQ diseases, and circulating lncRNAs are among the most promising novel candidates in the search for non‐invasive biomarkers for the diagnosis and prognosis of polyQ diseases. In this review, we describe the emerging roles of lncRNAs in polyQ diseases and provide an overview of the general biology of lncRNAs, their implications in pathophysiology and their potential roles as future biomarkers and applications for therapy.
Prenatal caffeine exposure: association with neurodevelopmental outcomes in 9‐ to 11‐year‐old children
Authors: Zhang Rui , Manza Peter , Volkow Nora D.
Published: July 2021

Background

Despite the widespread use of caffeine including consumption during pregnancy, the effect of prenatal caffeine exposure on child brain development and behavior is unclear.

Methods

To address this, we used data from the Adolescent Brain and Cognitive Development Study (n = 11,875 children aged 9–11 years from 22 sites across the United States). We explored the associations between prenatal caffeine exposure and various developmental outcomes including birth outcomes, physical health, behavior problems, cognition, substance use and brain structure in children, and evaluated dose effects.

Results

Among 9,978 children (4,745 females) who had valid data for prenatal caffeine exposure and whose mothers did not use drugs of abuse after knowing of pregnancy, 4,170 (41.79%) had no prenatal caffeine exposure, 2,292 (22.97%) had daily, 1,933 (19.37%) had weekly, and 1,583 (15.86%) had less than weekly exposures. Prenatal caffeine exposure including the widely recommended ‘safe’ dose was associated with greater externalizing problems, whereas greater BMI and soda consumption were only observed in children with high dose exposures (3+ per day). Notably, the effect size for association of externalizing problems with prenatal caffeine exposure was comparable with that reported for prenatal alcohol (The American Journal of Psychiatry, 177, 2020 and 1060) and prenatal cannabis (JAMA Psychiatry, 78, 2020 and 64) exposures from previous ABCD publications. Additionally, prenatal caffeine exposure was associated with brain structural changes that included greater posterior and lower frontal cortical thickness and altered parietooccipital sulcal depth.

Conclusions

The recommended ‘safe’ dose of caffeine during pregnancy should be carefully studied to assess whether the behavioral and brain correlates observed here are clinically relevant and determine whether it needs adjustment. Because of the high prevalence of caffeine use in the general population, studies on prenatal exposure to drugs of abuse should include prenatal caffeine use as a covariate.
Resectability of underwater endoscopic mucosal resection for duodenal tumor: A single‐center, retrospective pilot study
Authors: Toya Yosuke , Endo Masaki , Yamazato Masanao , Yamada Shun , Kumei Tomo , Hirai Minami , Eizuka Makoto , Morishita Toshifumi , Akasaka Risaburo , Yanai Shunichi , Uesugi Noriyuki , Sugai Tamotsu , Matsumoto Takayuki
Published: July 2021

Background and Aim

Underwater endoscopic mucosal resection (U‐EMR) has been attracting much attention as treatment for patients with nonampullary duodenal epithelial tumors (NADETs). We aim to compare treatment outcomes, including submucosal resectability, between patients undergoing U‐EMR and conventional endoscopic mucosal resection (C‐EMR) for NADET.

Methods

We conducted a retrospective review of 38 patients with NADET treated by U‐EMR or C‐EMR. In the resected specimens, we measured the horizontal length, the vertical distance from the muscularis mucosa to the margin at the deepest site, and the overall submucosal area. The submucosal index (SMI) was defined as the overall submucosal area divided by the largest horizontal length. These values and other treatment outcomes were compared between NADETs resected by U‐EMR and C‐EMR.

Results

The median size of lesions was 7 mm with a range of 3–13 mm. Although the incidence of adverse events and the rates of en bloc and R0 resection were not different in the two groups, the median procedure time was significantly shorter in the U‐EMR group (11 min vs 13 min; P = 0.045). The median submucosal depth at the deepest site (1.22 mm vs 1.08 mm; P = 0.38) and the median SMI (0.44 vs 0.41; P = 0.42) were not different between groups.

Conclusions

The resectability between NADETs treated by U‐EMR and C‐EMR was comparable. These results, together with the shorter procedure time required for U‐EMR, suggest that U‐EMR may have the potential to be the first choice for small to medium‐sized NADET.
The use of midazolam as an appetite stimulant and anxiolytic in the common marmoset (Callithrix jacchus)
Authors: Herrod Jessica Ann , Avelino Janelle Arcey , Schonvisky Kayla Marie , Lynch Jessica Kay , Hutchinson Eric Kenneth , Izzi Jessica Marie
Published: July 2021

Background

Food avoidance secondary to disease or stress can lead to weight loss and rapid deterioration of clinical condition in the common marmoset (Callithrix jacchus). Currently, there are no data supporting the use of any pharmaceuticals as an appetite stimulant in this species; however, benzodiazepines are frequently used for this purpose in other species.

Methods

Six marmosets were used in a crossover study design to evaluate the benzodiazepine midazolam as an appetite stimulant and anxiolytic. Total food intake (TFI) and latency to eat (LTE) were measured following administration of oral and injectable midazolam in non‐anxious and anxious states.

Results

Injectable midazolam increased TFI and decreased LTE in anxious marmosets, but had no effect in non‐anxious animals. Oral midazolam had no effect on appetite in either state.

Conclusions

Injectable midazolam may be an effective treatment for anxiety‐induced inappetence in marmosets. Individual response to both oral and injectable midazolam may vary.
Midface 3D restoration with an innovative high G’ filler
Authors: Muti Gabriele F.
Published: July 2021

Background

In the evaluation of the facial aging, the midface certainly represents the part that undergoes the most modifications and in which the aging process is most evident. The filling and redefinition of this part are fundamental to modify the perception of the age of the face and create a global rejuvenation effect. In general, high G’ fillers with a deep implant are used to treat the midface, taking advantage of the high lifting capacity and persistence of the implant in place.

Methods

We report our experience in the treatment of 20 patients with a hyaluronic acid (HA) filler based on an innovative crosslinking technology (XTR™—eXcellent Tridimensional Reticulation) for midface treatment. GAIS (Global Aesthetic Improvement Scale) at 1 month and 3 months after treatment was evaluated as primary endpoint. Patient satisfaction with the overall appearance, repeatability of treatment, and also an instrumental evaluation of the improvement were performed.

Results

Global Aesthetic Improvement Scale and patient satisfaction were very good 1 month and 3 months after treatment. The majority of patients said they would undergo treatment again. Clinical results were confirmed by instrumental evaluation.

Conclusion

The treatment of midface with this innovative HA high G’ filler is really effective in restoration of the volumes and in reshaping the curves of zygomatic area.
Fuzzy‐based method for efficient seismic performance evaluation of structures with uncertainty
Authors: Javidan Mohammad Mahdi , Kim Jinkoo
Published: July 2021

Seismic performance evaluation of a large inventory of old structures with no design document is a time‐consuming and costly task. In this research, a fuzzy‐based method and its toolbox are developed to efficiently approximate the seismic performance of structures with lack of structural information. The uncertain parameters are approximated as fuzzy numbers based on statistical studies on existing buildings, empirical formulas, alternative analysis methods, visual assessment, and design codes. The statistical database provided in this research can be valuable to make approximation for seismic performance of structures. The accuracy and applicability of the developed method are demonstrated using two real structures. Furthermore, the applicability of this study is demonstrated using the sensitivity and life‐cycle cost analysis of the case study structures. It is observed that the proposed method can approximate the seismic performance of a structure in a considerably short time with an acceptable trade‐off compared with more costly and time‐consuming site evaluations and detailed computations.
Neurodegenerative movement disorders: An epigenetics perspective and promise for the future
Authors: Murthy Megha , Cheng Yun Yung , Holton Janice L. , Bettencourt Conceição
Published: July 2021

Neurodegenerative movement disorders (NMDs) are age‐dependent disorders that are characterised by the degeneration and loss of neurons, typically accompanied by pathological accumulation of different protein aggregates in the brain, which lead to motor symptoms. NMDs include Parkinson's disease, multiple system atrophy, progressive supranuclear palsy, and Huntington's disease, among others. Epigenetic modifications are responsible for functional gene regulation during development, adult life and ageing and have progressively been implicated in complex diseases such as cancer and more recently in neurodegenerative diseases, such as NMDs. DNA methylation is by far the most widely studied epigenetic modification and consists of the reversible addition of a methyl group to the DNA without changing the DNA sequence. Although this research field is still in its infancy in relation to NMDs, an increasing number of studies point towards a role for DNA methylation in disease processes. This review addresses recent advances in epigenetic and epigenomic research in NMDs, with a focus on human brain DNA methylation studies. We discuss the current understanding of the DNA methylation changes underlying these disorders, the potential for use of these DNA modifications in peripheral tissues as biomarkers in early disease detection, classification and progression as well as a promising role in future disease management and therapy.
The Evolution of Geographic Thought
Authors: Wyly Elvin
Published: July 2021

The formal institutional entity we today call ‘Geography’ only exists because of nineteenth‐century struggles over the science, theology, and politics of human evolution. Old struggles continue even as today’s geographic thought evolves at an accelerating pace, amidst the dramatic transformations wrought by CRISPR gene‐editing technoscience and the consolidation of computational‐cultural forms of accumulation in surveillance capitalism. This paper explores some of the contradictions of these old and new processes in the evolution of geography and the geography of evolution. New, unconventional perspectives are possible with a synthesis of David Harvey’s theory of co‐evolutionary spheres of change in human and non‐human relations, Vine Deloria, Jr.’s analysis of Indigenous/Western settler‐colonial dialectics of space and time, and Pierre Teilhard de Chardin’s portrayal of a noösphere of planetary consciousness. On the advancing frontiers of the Delorian noösphere, humanity confronts a proliferation of neo‐Lamarckian challenges and opportunities to create new geographies of planetary evolution.
Time–temperature indicators versus temperature indicators for transfusion practice: Application in the real hospital setting
Authors: Park Mikyoung , Hur Mina , Kim Hanah , Oh Kyungmi , Ko Dae‐Hyun , Chung Yousun
Published: July 2021

Background and Objectives

Temperature indicators (TIs) are used to monitor the surface temperature of red blood cell (RBC) units. We compared the utility of a newly developed time–temperature indicator (TTI) prototype, Freshzone TTI (FZTTI) (Freshzone, Seoul, South Korea) and two US Food and Drug Administration–approved TIs, Safe‐T‐Vue 10 (STV10; Temptime Corporation, Morris Plains, NJ) and Blood Temp 10 (BT10; Timestrip UK Ltd, Cambridge, UK).

Materials and Methods

FZTTI, STV10 and BT10 were attached to 91 RBC units after issue (including eight units that were stored in refrigerators in the ward before transfusion). The time for colour change (CC) was monitored based on the 30‐min rule. The CC of FZTTI indicated the total time elapsed since the temperature of RBC units exceeded 10°C, and the CC of STV10 and BT10 indicated that the temperature of RBC units exceeded 10°C.

Results

In 83 units, the median time for CC differed significantly between FZTTI and the TIs (51.4 min in FZTTI vs. 13.9 min in STV10 and 10.5 min in BT10, both at p < 0.001). In addition, 95.2% (n = 79) of FZTTI tags changed colour after 30 min of issue, whereas 96.4% (n = 80) of STV10 and 98.8% (n = 82) of BT10 changed colour within 30 min of issue. In the eight units stored in refrigerators, the time for CC between the TTI and TIs was significantly different.

Conclusion

FZTTI outperformed the TIs, indicating that it is a feasible option for use in transfusion practice.
A 3-Dimensional Numerical Thermal Analysis for the Configuration Effect of a Single and Double U-tube on the Borehole Performance
Authors: Tarrad Ali H.
Published: July 2021

The thermal design of a borehole is the most important task in the thermal performance evaluation of a geothermal coupled heat pump system. It demands an understanding of the U-tube orientation and configuration in the borehole. The COMSOL Multiphysics 5.4 software was utilized in a 3-dimensional numerical simulation model to investigate the thermal performance of a single and double U-tube embedded in the borehole. The water was chosen as a thermal fluid carrier and circulated in the borehole heat exchanger at a mass flow rate range of (0.14–0.34) kg/s and inlet temperature of (33) °C. The configurations of the double U-tubes were assigned as a parallel flow in a cross U-tube arrangement (PFCD), a parallel flow in a parallel double U-tube in situ (PFPD), a series flow circuiting in a cross double U-tube geometry (SFCD), and a series flow in a parallel double U-tube installation (SFPD). The steady-state numerical solutions were compared at fixed borehole configuration and fixed operating conditions. Results showed that the (PFPD), (PFCD), and (SFPD) U-tube configurations have achieved a higher heat load than that of the single U-tube ones by (16–19) %, (13–16) %, and (15–18) % respectively. They produced a higher heat load than that of the series flow in a cross double U-tube (SFCD) arrangement by (30–31) %, (27–30) %, and (29–31) % for the (PFPD), (PFCD) and (SFPD) configurations respectively.
Maximizing Wind Turbine Efficiency by Using Soft Switching Multiple Model Predictive Control
Authors: Mehdizadeh Gavgani Babak , Farnam Arash , De Kooning Jeroen D. M. , Crevecoeur Guillaume
Published: July 2021

Variable speed small to medium wind turbines need to cope with the intermittent nature of wind speed at lower altitudes. This imposes challenges on optimally tracking the maximum power point (MPP) during partial load and makes the wind turbine dynamics highly nonlinear. As a result, using one linear controller around a specific operating point may not guarantee acceptable performance in the other operating points. In addition, wind speed variations cause fluctuations in the output power of the turbine. The Soft Switching Multiple Model Predictive Control (SSMMPC) technique is introduced to tackle the latter problems when considering multiple linear models around various operating points (MPPs) approximating the nonlinear dynamics. The gap metric method is used to assess how close different linear models are with respect to each other. The closed loop system stability is validated using Lyapunov theory. The controller performance is investigated and compared with a bidirectional TSR-based controller through simulations using the FAST NREL 10kW wind turbine model. The results verify the improvements that can be attained by using SSMMPC in terms of higher maximum power point tracking quality, lower generator torque oscillations and smoother output power, consequently.
Feasibility Study of Refuelling Infrastructure for Compressed Hydrogen Gas Long-Haul Heavy-Duty Trucks in Canada
Authors: Yaïci Wahiba , Longo Michela
Published: July 2021

In view of serious environmental problems occurring around the world and in particular climate change caused significantly by dangerous CO2 emissions into the biosphere in the developmental process, it has become imperative to identify alternative and cleaner sources of energy. It is now indisputable that there cannot be sustained development or meaningful growth without a commitment to preserve the environment. Compressed hydrogen is being considered as a potential fuel for heavy-duty applications because it will possibly substantially reduce toxic greenhouse gas emissions. The cost of hydrogen will be a main element in the acceptance of compressed hydrogen internal combustion vehicles in the marketplace since of its effect on the levelized cost of driving. The cost of hydrogen at the pump is determined by its production cost, which is mainly a function of the feedstock and process utilised, the distribution cost and the refuelling station cost.

This paper investigates the feasibility of implementing a nationwide network of hydrogen refuelling infrastructure in order to accommodate a conversion of Canada’s long-haul, heavy-duty truck fleet from diesel fuel to hydrogen. This initiative is taken in order to reduce vehicle emissions and support Canada’s commitments to the climate plans supporting active transportation infrastructure, together with new transit infrastructure, and zero emission vehicles.

Two methods, Constant Traffic and Variable Traffic, along with data about hydrogen infrastructure and vehicles, were developed to estimate fuelling requirements for Canada’s long-haul, heavy-duty truck fleet. Furthermore, a thorough economic study was conducted on various test cases to evaluate how diverse variables affects the final selling price of hydrogen. This provided insight with the understanding of what factors go into pricing hydrogen and if it can compete against diesel in the trucking market.

Results revealed that the cost to purchase hydrogen is the greatest factor in the pump price of hydrogen. Due to the variability in hydrogen production, however, there is no precise cost, which makes predictions difficult. Moreover, it was found that the pump price of hydrogen is, on average, 239% more expensive than diesel fuel.

Future work should concentrate on the costs and logistics of high-capacity hydrogen refuelling stations, which is required to deliver fuel to a fleet of long-haul, heavy-duty trucks. A breakdown of hydrogen production costs, with regard to the Canadian landscape and the requirements of a long-haul, heavy-duty truck fleet, may possibly give further accurate predictions of those made in this study.
Simulations of Solar Power Systems to Provide Electricity to a Model Water Desalination Plant in Floreana Island, Ecuador
Authors: Amoroso Fernando , Hidalgo-León Rubén , Litardo Jaqueline , Granja Alejandro , Calderón Jackeline , Siguenza-Alvarado Diego , Soriano Guillermo
Published: July 2021

This work shows the techno-economic comparison of the design of two solar photovoltaic systems: 1) on-grid (G-SPVS) and 2) off-grid (SPVS). Both schemes aim to supply electricity to a model water desalination plant located in Floreana Island, Ecuador. The annual load profiles and other operational details of the case study were previously obtained. For this research, a period of 15-years was analyzed. During this time, the maximum power of water pump system remained constant and represented the highest percentage of the electrical load, which changed each year influenced by the drinking water requirements of the population. Results from the HOMER PRO simulations showed that the SPVS produced higher surpluses of electricity. In contrast, the G-SPVS exhibited lower net present cost (NPC) and cost of energy (COE).
Terrestrial Heat Repository for Months of Storage (THERMS): A Novel Radial Thermocline System
Authors: Ho Clifford K. , Gerstle Walter
Published: July 2021

This paper describes a terrestrial thermocline storage system comprised of inexpensive rock, gravel, and/or sand-like materials to store high-temperature heat for days to months. The present system seeks to overcome past challenges of thermocline storage (cost and performance) by utilizing a confined radial-based thermocline storage system that can better control the flow and temperature distribution in a bed of porous materials with one or more layers or zones of different particle sizes, materials, and injection/extraction wells. Air is used as the heat-transfer fluid, and the storage bed can be heated or “trickle charged” by flowing hot air through multiple wells during periods of low electricity demand using electrical heating or heat from a solar thermal plant. This terrestrial-based storage system can provide low-cost, large-capacity energy storage for both high- (∼400–800°C) and low- (∼100–400°C) temperature applications. Bench-scale experiments were conducted, and computational fluid dynamics (CFD) simulations were performed to verify models and improve understanding of relevant features and processes that impact the performance of the radial thermocline storage system. Sensitivity studies were performed using the CFD model to investigate the impact of the air flow rate, porosity, particle thermal conductivity, and air-to-particle heat-transfer coefficient on temperature profiles. A preliminary technoeconomic analysis was also performed to estimate the levelized cost of storage for different storage durations and discharging scenarios.
Heat Transfer Modeling in a Counter-Current Moving-Bed Tubular Reactor for High-Temperature Thermochemical Energy Storage
Authors: Huang Wei , Million Eric , Randhir Kelvin , Petrasch Joerg , Klausner James , AuYeung Nick , Li Like
Published: July 2021

An axisymmetric model coupling counter-current gas-solid flow, heat transfer, and thermochemical redox reactions in a moving-bed tubular reactor was developed. The counter-current flow enhances convective heat transfer and a low oxygen partial pressure environment is maintained for thermal reduction within the reaction zone by using oxygen depleted inlet gas. A similar concept can be used for the oxidation reactor which releases high-temperature heat that can be used for power generation or as process heat. The heat transfer model was validated with published results for packed bed reactors. After validation, the model was applied to simulate the moving-bed reactor performance, through which the effects of the main geometric parameters and operating conditions were studied to provide guidance for lab-scale reactor fabrication and testing.
Numerical Research on Heat Transfer Characteristics Analysis of Two Particles in Supercritical Water
Authors: Li Xiaoyu , Wu Zhenqun , Wang Huibo , Jin Hui
Published: July 2021

In the supercritical water (SCW)-particle two-phase flow of fluidized bed, the particles that make up the particle cluster interact with each other through fluid, and it will affect the flow and heat transfer. However, due to the complex properties of SCW, the research on particle cluster is lacking, especially in terms of heat transfer. This research takes two particles as an example to study the heat transfer characteristics between SCW and another particle when one particle exists. This research uses the distance and angle between the two particles as the influencing factors to study the average heat transfer rate and local heat transfer rate. In this research, it is found that the effect is obvious when L/D = 1.1. When L = 1.1D, the temperature field and the flow field will partially overlap. The overlap of the temperature field will weaken the heat transfer between SCW and the particle. The overlap of the flow field has an enhanced effect on the heat transfer between SCW and the particle. The heat transfer between SCW and particles is simultaneously affected by these two effects, especially local heat transfer rate. In addition, this research also found that as the SCW temperature decreases, the thermal conductivity and specific heat of SCW increases, which enhances the heat transfer between SCW and the particles. This research is of great significance for studying the heat transfer characteristics of SCW-particle two-phase flow in fluidized bed.
Estimation of Fuel Quality Using Statistical Regression-Based Analysis of Leidenfrost Droplets
Authors: Bhati Awan , Acharya Palash V. , Ezekoye Ofodike A. , Bahadur Vaibhav
Published: July 2021

Accurate measurement of fuel quality is critical for automotive applications as it impacts engine performance and emissions. A number of techniques have been proposed to measure fuel quality including acoustic wave speed sensors, chemometric modeling, near-infrared spectrophotometry, Raman spectroscopy etc. All of these techniques are complex in nature and require expensive equipment. In contrast, we propose a novel, simple and rapid method for estimating fuel quality in field environments. This involves measuring the evaporation time of fuel droplets in the Leidenfrost state, and using the results of statistical data analysis conducted on an experimental data bank comprising evaporation time data for similar droplets. The Leidenfrost state refers to a liquid droplet hovering on its own vapor layer on a superheated surface. To showcase our approach, evaporation time was measured for droplets consisting of isopropyl alcohol (IPA) and water blends with varying parameters such as IPA fraction (0-1), droplet volume (20–100μL) and surface temperature (200–340 °C). The resulting data bank (96 data points) was used to train and evaluate the performance of a polynomial regression (using a semilogarithmic transformation) model in predicting the evaporation time as a function of the above-mentioned parameters. R2 accuracies of 97.34% (training data), 96.82% (test data), 97.46% (total) and a relative error within ± 0.25% for the entire dataset was obtained using the regression model, which highlights the predictive capabilities of our approach.
Numerical Simulation and Flame Characteristics Analysis of Non-Premixed Swirling Combustion
Authors: Su Yi , Zhang Bin , Hou Junqing , Chen Yifeng , Jiang Jieyu , Li Wei
Published: July 2021

Swirling flames are important in practical industrial combustors. The dynamic characteristics of swirling flames form complex velocity and temperature fields, which indicate combustion efficiency and influence pollutant emission. A reliable numerical simulation that can calculate the entire velocity and temperature fields is required to understand and investigate the underlying combustion mechanism. The governing equations of the methane swirling combustion process consist of the mass conservation, Navier-Stokes, and energy equations, all of which are solved by the SIMPLE algorithm based on finite volume method. This study performed a simulation using the realizable k-ε and non-premixed models in conjunction with the GRI Mech 3.0 mechanism. The characteristics of swirling combustion were analyzed on the bases of visualizations of temperature distribution, velocity distribution, and streamlines. In each cross section with varying heights from the nozzle, the high velocity and high temperature areas showed similar closed or semi-closed annular structures. In the central longitudinal section, the V-shaped high temperature and high velocity regions showed the swirling structure of the combustion flow field. The high temperature area did not coincide with the high velocity area but was located relatively downstream. The high velocity area was in the periphery of the high temperature area. Furthermore, the effects of swirl blade position on methane combustion characteristics were discussed. The validity of the numerical simulation results was verified by the simultaneous laser measurement of 3D temperature and velocity fields in the swirling flame.
Study of Boiling Heat Transfer on Heterogeneous Wetting Surface With MD Simulation
Authors: Liu Zeyu , Liu Runkeng , Li Peng , Xu Anyi , Liu Zhenyu
Published: July 2021

Wettability has been proved as an important issue to the thermal transport at solid-liquid interface at different scales, however, its enhancement mechanism has not been clearly understood till now. In this study, the nucleate boiling behavior of argon fluid on heterogeneous wetting surfaces were examined with the non-equilibrium molecular dynamics (MD) method, the ring-patterned and stripe-patterned schemes were designed and analyzed, respectively. By comparing the boiling inception time and evaporation rate of liquid argon atoms, it is found that the ring-patterned surface shows an advantage in the nucleate boiling heat transfer compared with the stripe-patterned one. The differences in heat transfer characteristics for different surfaces can be explained through the qualitative analysis of fluid density distribution and solid-fluid interaction energy. Furthermore, the boiling phenomena on ring-patterned surfaces with alternated hydrophilic and hydrophobic intervals were simulated to study the influence of area fraction of hydrophilic region on the heat transfer performance. It is observed that bubble nucleus firstly appears over the hydrophobic region of the substrate. The substrate with more hydrophilic area will have a better heat transfer performance. It is also demonstrated that there is an optimal area fraction, which can make the evaporation rate of fluid reach the highest value. The findings in this work can contribute to the design and fabrication of nanocoating surface to enhance its heat transfer performance under high heat flux condition.
Numerical Investigation of Porosity Effect on Confined Round Impinging Jets of Nanofluids in Aluminum Foams
Authors: Buonomo Bernardo , di Pasqua Anna , Manca Oronzio , Nappo Sergio
Published: July 2021

In this paper a numerical study on mixed convection in confined impinging round jets in a porous media is carried out. Pure water and Al2O3/water based nanofluids are employed as working fluids; a single-phase model approach has been applied to evaluate their properties. A two-dimensional domain is analyzed and different Peclet are considered. The Rayleigh number is fixed equal to 30000. The thermal non-equilibrium energy condition (LTNE) is assumed to accomplish two-dimensional simulations on the metal foam section. The examined aluminum foams are characterized by distinct porosity (ε), from 0.90 to about 0.97, for different values of pores per inch (PPI), equal to 5, 10, 20 and 40. The particle volume concentrations range from 0% to 4% and the particle diameter is equal to 30 nm. The target surface is heated by a constant temperature value, calculated according to the value of Rayleigh number. The results show that the convective heat transfer coefficients increase with increasing of values of Peclet number and nanoparticle concentration. Furthermore, the heat transfer coefficient shows a different behavior at varying porosity for different Peclet and Rayleigh numbers. In addition, temperature profiles are presented for the fluid and solid phases of the porous zone.
Validation Of Multiphase Computational Model Using Experimental Study of Air/Mist Film Cooling
Authors: Abdelmaksoud Ramy , Wang Ting
Published: July 2021

A numerical study has been performed to validate the multiphase CFD model (DPM) by comparing its results to the experimental data of an air/mist film cooling study. The complete experimental test section was simulated including all the details including all the five holes, side walls effect, partially opened top wall, the conjugate bottom wall, the initial droplet distributions from the actual data, and the long boundary layer developing region upstream of the cooling holes. The effects of different particle distributions, the breakup and coalescence models, and the conjugate wall on the adiabatic film cooling effectiveness were investigated. The multiphase CFD model employs an Eulerian-Lagrangian approach. The Eulerian method is used for the continuous phase including air and water vapor and the Lagrangian method in terms of the discrete phase model (DPM) is used to simulate the dispersed phase (e.g., mist or liquid droplets) in a continuous phase (e.g., air). The overall consistency between the computational prediction and experimental data is within 0.2% for the air-only case and 7% for the mist case. The results showed that considering the wall using the conjugate heat transfer technique significantly provided better agreement with the experimental data than without including the wall. The non-uniform particle distribution provided better agreement with the experimental results near the film cooling hole exit.
Drying Characteristics and Quality of Fresh White Waxy Corn Under Different Drying Methods
Authors: He Yanling , Huang Dan , Chen Yongjia , Men Kaiyang , Sherif S. A. , Li Wei
Published: July 2021

The drying characteristics and drying quality of fresh white waxy corn were investigated under three different drying methods (sun drying, hot-air drying and far-infrared drying) and different drying temperatures (55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C). The optimal drying method and drying condition were obtained by comparing the drying time and drying quality including damage rate, rehydration capacity and the contents of protein, fatty acid and starch. The results showed that the drying time of sun drying was the longest, while the drying quality was the best, i.e., the damage rate was the lowest and the nutrient retention was the highest. The far-infrared drying time was shorter and the quality was better than that of hot air drying. The higher the temperature, the faster the drying rate. The optimal drying temperature was 60 °C under far-infrared drying, which can effectively remove the water and keep the food quality. Besides, the drying rate was faster than hot air, and the color of the dried products was brighter. When hot air drying was used, the value of fatty acids did not change much below 65 °C, but it rose sharply above 65 °C. The optimal drying temperature was 65 °C, under which the drying rate was moderate and the quality was relatively good. If the production cost was considered, sun drying was the best, following the 60 °C far-infrared drying. This conclusion can provide a reference for the drying conditions of corn after harvest in agricultural production, and to a certain extent provide suggestions for the later drying treatment methods and treatment temperatures of fresh white waxy corn.
Effect of Build Angle on Additively Manufactured Aluminum Alloy Surface Roughness and Water Wetting Ability
Authors: Bailey Christopher M. , Thompson Scott M. , Derby Melanie , Morrow Jordan , Weeks Cameron
Published: July 2021

Additive manufacturing (AM) allows for the fabrication of complex metallic specimens which are otherwise very difficult or impossible to create using traditional manufacturing methods. For multi-phase heat spreaders such as vapor chambers, complex internal geometry lends itself well to AM as new design features can be realized. The internal geometries of vapor chambers frequently involve several thin pillars, which act as wicking structures and support a small internal cavity in which the phase change of a liquid, usually water, provides a means to effectively ‘spread’ a high heat flux throughout a larger area. In this case study, Laser Powder Bed Fusion (L-PBF) AM was utilized to create a series of aluminum alloy (AlSi10Mg) support pillars of fixed height with varying filet angles and build orientations (0°, 10°, 20°, 30°, 40°, 50° and 60° from the normal surface) to determine effects on surface roughness and resolution. Surface-to-water contact angles were measured on rinsed, un-polished surfaces, and microscopy was employed to obtain images demonstrating surface roughness profiles. This was done on both heated and unheated surfaces. Results clearly demonstrate that the surface roughness of upward and downward-facing surfaces during L-PBF depends on build orientation. The observational findings of this experiment showed that the surface roughness on surfaces representing horizontally oriented faces decreased as the printing orientation increased. This indicates that one must be cognizant of printing orientation for the L-PBF of capillary structures. A change in surface roughness as a result of printing orientation effects the heat transfer within an enclosed space due to a change in contact angles between the liquid and the heated surface. The results of this study will aid in future design considerations of heat pipes for their additive manufacture via current L-PBF technology.