High Variability Research Articles

Six Sigma-Based Mathematical Optimization Framework for Flux-Switching Machines: A Roadmap for Quality, Performance, and Manufacturing Tolerances

Flux-switching wound field machines (FSWFMs) offer high torque density and independence from rare-earth materials, making them promising candidates for sustainable electric vehicles and industrial applications. However, their adoption is limited by challenges such as high torque ripple, efficiency variations, and sensitivity to manufacturing tolerances. This study presents a Design for Six Sigma (DFSS) optimization framework that integrates sensitivity analysis, response surface modeling (RSM), and multi-objective genetic algorithms to address these challenges. The optimized solution reduces torque ripple by 7.69%, improves torque output, and enhances energy efficiency. By incorporating Six Sigma principles, the framework ensures robust performance under manufacturing variations, bridging the gap between theoretical optimization and practical implementation. This scalable and efficient methodology establishes FSWFMs as viable solutions for industrial applications, revolutionizing electric machine design.

Invasion of temperate riparian forests by Acacia dealbata affects macroinvertebrate community structure in streams

The riparian forest determines many of the stream characteristics such as physicochemical variables and the availability and quality of food resources for aquatic communities. In central Portugal, native mixed deciduous forests are being heavily invaded by Acacia dealbata, which is an evergreen and nitrogen-fixing tree species, but effects on stream benthic macroinvertebrate communities are unknown. We assessed invasion effects on macroinvertebrate communities by comparing streams flowing through native forests (native streams) and streams flowing through forests heavily invaded by A. dealbata (invaded streams), in central Portugal. We did not find major differences in macroinvertebrate abundance, total taxa richness or diversity between native and invaded streams, due to high variation among native streams. However, taxonomic structure of macroinvertebrate communities differed between stream types, with invaded streams showing lower percentage of sensitive taxa. Macroinvertebrate communities structure based on functional feeding groups also differed between stream types, with a tendency for higher abundance of shredders and scrapers/grazers and lower abundance of filter feeders in native than invaded streams, probably due to altered composition of leaf litter inputs and canopy cover within invaded streams. Our findings suggest that invasion by A. dealbata affect macroinvertebrate community mostly in terms of taxonomic and functional structure. Since A. dealbata is rapidly spreading in all southern Europe, this study highlights the importance of enhancing the comprehension of its impact on aquatic communities to identify ecological risks and formulate effective mitigation strategies.

Ecosystem Services Linked to Extensive Sheep and Goat Farming in Mountain Areas: A Global Literature Analysis Using Text Mining and Topic Analysis

Mountain ecosystems are unique and complex environments characterised by their high altitudes, steep slopes, and significant climatic variations [...]

Adaptive ensemble loss and multi-scale attention in breast ultrasound segmentation with UMA-Net.

The generalization of deep learning (DL) models is critical for accurate lesion segmentation in breast ultrasound (BUS) images. Traditional DL models often struggle to generalize well due to the high frequency and scale variations inherent in BUS images. Moreover, conventional loss functions used in these models frequently result in imbalanced optimization, either prioritizing region overlap or boundary accuracy, which leads to suboptimal segmentation performance. To address these issues, we propose UMA-Net, an enhanced UNet architecture specifically designed for BUS image segmentation. UMA-Net integrates residual connections, attention mechanisms, and a bottleneck with atrous convolutions to effectively capture multi-scale contextual information without compromising spatial resolution. Additionally, we introduce an adaptive ensemble loss function that dynamically balances the contributions of different loss components during training, ensuring optimization across key segmentation metrics. This novel approach mitigates the imbalances found in conventional loss functions. We validate UMA-Net on five diverse BUS datasets-BUET, BUSI, Mendeley, OMI, and UDIAT-demonstrating superior performance. Our findings highlight the importance of addressing frequency and scale variations, confirming UMA-Net as a robust and generalizable solution for BUS image segmentation.

Diurnal and daily fluctuations in levels of the urinary oxidative stress marker 8-hydroxyguanosine in spot urine samples

BackgroundUrinary 8-hydroxyguanosine (8-OHGuo) levels serve as a biomarker for oxidative stress and hydroxyl radical–induced RNA damage. Evaluating the diurnal and daily fluctuations in urinary 8-OHGuo excretion levels is essential for understanding its implications. However, research in this area remains limited. In this study, we aim to investigate the diurnal and daily fluctuations in 8-OHGuo levels as well as the factors that influence these variations, using spot urine samples.MethodsUrine samples were collected from seven healthy participants during each urination from the time of awakening until 24:00 h to evaluate diurnal variations. To assess daily fluctuations, urine samples were collected from 18 healthy participants at the time of awakening for 23 consecutive days. The urinary 8-OHGuo levels were measured using an HPLC-ECD method.ResultsNo significant variations were observed in the diurnal levels of urinary 8-OHGuo among non-smokers. Conversely, the daily variation of 8-OHGuo in the urine of the smoker was significant, with a coefficient of variation of 18.71%. Each individual maintained a characteristic value despite some diurnal fluctuations. Furthermore, the daily levels of 8-OHGuo exhibited a range of variations influenced by lifestyle factors, including mental state, sleep duration, smoking, menstrual cycle, and dietary habits.ConclusionAs a specific marker of RNA oxidation, 8-OHGuo provides unique insights distinct from those provided by the widely used DNA oxidation marker 8-hydroxydeoxyguanosine as an indicator of oxidative stress. Urinary 8-OHGuo could serve as a valuable biomarker for managing and preventing oxidative stress–related diseases, provided that the specific range of daily variations is established. The high daily variation in urinary 8-OHGuo levels necessitates the use of multiple samples to accurately determine individual levels. However, further research with large sample sizes will help to validate these findings.

P1126 Patterns of conventional therapy use and drivers of initiation for advanced therapy in Inflammatory Bowel Disease: A European situational analysis

Abstract Background Data suggest limited use of advanced therapies (AT) in inflammatory bowel disease (IBD) despite the accumulating data for the benefits of early, broader AT use.1-3 We evaluated barriers to AT use in IBD using a multimodal approach. Methods Market research was conducted June-November 2023. Quantitative survey on prescribing trends amongst gastroenterologists (GEs) prescribing ATs was conducted to capture AT initiation drivers in Germany, Italy, UK and US; questions for this survey were identified in qualitative interviews. GEs cycling an average of 0-1 and ≥2 conventional therapies (CTs) before initiating AT were classified as low and high cyclers, respectively. The COM-B (Capability, Opportunity, Motivation and Behaviour) model was used for behavioural analysis.4 Results Qualitative analysis covered responses from 62 participants (28 patients [pts], 24 GEs, 7 nurses, 3 pt organisation representatives), and quantitative analysis – from 142 GEs (Germany, 30; Italy, 30; UK, 30; US, 52) currently prescribing ATs, with 559 pt report forms (ulcerative colitis [UC], 280; Crohn’s disease [CD], 279) collected. CT cycling was more prevalent in UC vs CD; AT treatment was less likely in pts with UC vs CD (Figure). Differences among GEs by geography were only partially explained by cost containment in highly regulated markets (eg, Italy, UK). High cycling variations were linked to behavioural and belief-driven factors as illustrated by the notable use (7-20%) of 5-aminosalicylates in CD despite the lack of clinical guideline support. In behavioural analysis, AT initiation barriers included a lack of awareness of AT value and prescribing approach of exhausting all CT options before initiating AT. Low vs high cyclers placed higher importance on patient preference (UC, +16%; CD, +19%) and peer recommendations (UC, +13%; CD, +20%). In UC, the belief of exhausting all CT options before initiating AT was more important for high vs low cyclers (+9%). Qualitative research showed that the lack of clear guidelines disproportionately impacted high cyclers as they had reduced academic interest and limited capacity as contributors. Physician-relevant AT initiation drivers were the perceived CT risks and the growing recognition of the AT clinical value and long-term impact on the quality of life. Pt-relevant drivers included improved AT awareness and the ability and confidence for pts to self-advocate. Conclusion Cost containment and guideline variations could partially explain the observed geographic variations in AT use. Within any given country, clinical beliefs play a determining role. In Europe, a tangible increase in AT vs CT share could be achieved by encouraging GEs to initiate AT in pts with poor prognostic factors as per guideline suggestions.

Development of Automatic Waste Classification System using CNN-Based Deep Learning to Support Smart Waste Management

This research develops an automatic waste classification system using deep learning based on Convolutional Neural Network (CNN) to support the implementation of Smart Waste Management (SWM). The main objective of this research is to design and test a CNN model that is able to classify various types of waste, such as plastic, paper, organic, and other non-organic waste, with high accuracy and efficiency. The developed CNN model successfully achieved an accuracy rate of 94.86% on the training dataset. The system performed very well in classifying recyclable waste with a precision of 56.6% and recall of 63.5%, although it still faces challenges in the classification of organic waste with a precision of 45.7% and recall of 38.8%. This research also includes model validation using cross-validation techniques to ensure the generalizability of the model on different datasets. In addition, tests were conducted on external datasets to evaluate the robustness of the model under real-world conditions. Data preprocessing techniques such as image normalisation and data augmentation were used to improve the performance of the model. The results show that a CNN-based automated waste classification system has great potential to be implemented in SWM systems, enabling more efficient and automated waste management. However, there are still some challenges such as high variation in litter images and dataset limitations that need to be addressed for future development of a more robust system

Performance of a Thin CRCP Inlay Designed for a Five-Year Life: a Case Study

The steep uphill section of an interstate highway had experienced considerable damage in the form of serious rutting due to slow-moving heavy vehicles. The asphalt pavement had had to be rehabilitated every 4 years and a decision was made to mill and replace the top 180mm of the slow lane with a CRCP inlay. The inlay design was based on an anticipated 6 million equivalent 80 kN axles over five years and it was envisaged that a concrete overlay would be placed over the full width of the road at the end of this period. However, at the end of six years only approximately 0.25% of the area of the inlay had shown serious distress. It was decided to determine the remaining structural life of the pavement with a view to repairing failed areas permanently, rather than temporarily, if the remaining structural life was found to be significant. This paper describes the testing of behaviour and performance on a relatively highly cracked section of the inlay using the Heavy Vehicle Simulator (HVS). Although the test section had narrowly spaced transverse cracking prior to testing, no punch-outs could be created using the HVS. A detailed survey of the 26 lane km of inlay showed that failure did not necessarily occur at closely spaced cracks, but was more associated with edge loading, loss of slab support and poor quality concrete. It also became very clear that a high variation in concrete characteristics (and in particular concrete strength) resulted in a high risk of structural failure. The results were translated into transfer functions that have been included in cncPave, a mechanistically-based design method for concrete pavements developed for South African conditions.

Diet and trophic structure of fishes in the Barents Sea: between empty and full stomachs - large individual variability follows a common pattern.

More than 27,000 stomachs from 70 species of fish were collected from the Barents Sea in 2015. Quantitative stomach content expressed relative to the body weight of the predator fish (g g-1 as %) varied by four to five orders of magnitude for six species with the largest sample size (Atlantic cod Gadus morhua, haddock Melanogrammus aeglefinus, Greenland halibut Reinhardtius hippoglossoides, long rough dab Hippoglossoides platessoides, polar cod Boreogadus saida, and Atlantic capelin Mallotus villosus). The quantitative stomach contents of individual fish followed a common and strict statistical relationship for predator species or groups of species (by families), and for prey categories across predator species. The common pattern was log-normal-like and was modelled with good fit by different types of right-skewed distributions, that is, variants of the Box-Cox, generalized inverse Gaussian, inverse gamma, or gamma distributions. The long tail in the high end reflects high variation with no clear sign of a plateau, as could be expected from the concept of a "full stomach". This is interpreted to reflect that high stomach contents are rare events that are sampled at low frequencies. The maximum recorded stomach content varied from 1% to 34% of body weight for 55 species of fish, being positively correlated (R2 = 0.45) with sample size. About a third of the stomachs were empty, and the low tail of the log-normal-like distribution represents the transition to empty stomachs. The amount of food in the stomachs was overall low compared to maximum values, with mean and median of 2.0% and 1.1%, respectively, for the 17,873 stomachs containing food. Supported by bioenergetic considerations, this suggests relatively low feeding rates of the various fish predators but sufficient to meet their energy demands.

Application of Tradescantia-based test systems for the assessment of genotoxic effects of environmental radioactivity of undisturbed mountain soils (Aragats Massif, Armenia)

ABSTRACT Plant test systems are a sensitive way to detect the genetic effects of various contaminants in environmental compartments: water, soil and sediments. Biotesting of the genotoxicity of soil samples with various activity concentrations of naturally occurring (226Ra, 232Th, 40K) and artificial (137Cs) radionuclides in soil, from the territory of the Aragats Massif (Armenia) was carried out with the application of the Tradescantia micronucleus (Trad-MСN) and stamen hair mutation (Trad-SHM) bioassays of Tradescantia (clone 02) model test-object in the soil – plant system. Undisturbed soil sampling was performed in the southern slopes of the Aragats Massif, from different altitudes (from 1000 to 3200 m above sea level). The soils of the Aragats Massif exhibited a background level of naturally occurring materials (NORM) activity. The highest variability was indicated for 40K. The activity concentration of 137Cs in soils exhibited a naturally increased as the altitude increased. Tradescantia (clone 02) was grown on the undisturbed soils in the greenhouse. To determine the level of genotoxicity of the studied soil samples, the Tradescantia-based Trad-MCN and Trad-SHM tests were applied. The activity concentrations of NORM and artificial 137Cs in soil and phytomass were determined using an HPGe detector-based gamma spectrometer (Canberra). Tradescantia (clone 02) accumulated mainly 40K, accumulation of 226Ra observed in one soil sample. In the areas with elevated activity of NORM, levels of genotoxicity were significantly higher compared to the control soil sample with the low rate of spontaneous mutation frequency. The positive correlation between genetic damages of Tradescantia (MCN and SSH) and contents of 40K and 226Ra in soils was revealed. The obtained results indicated the possibility of using Trad-MCN and Trad-SHM tests of Tradescantia (clone 02) for biotesting of background radioactivity in natural areas.

Worker participation under digitalisation: Structure, power and varieties of union influence in two manufacturing sectors

Technological changes associated with the rise of digitalisation are sometimes envisioned as disrupting forces for the role of workers on the shopfloor. Whether these changes will lead to enhanced or reduced participation of labour and unions has been the subject of conjectures put forward by different schools of thought. The article proposes a framework mobilising various forms of participation to understand patterns of involvement under technological changes. An exploration of four cases in the aluminium and rubber manufacturing sectors in Québec (Canada) reveals a high variation of participation schemes, ranging from collective and formal to mixed (collective and formal, direct and informal), and direct and formal. The authors argue that patterns of participation at work should be understood as the outcomes of the material conditions (technology, markets, economic) in which workplaces are embedded in conjunction with the ability of workers and unions to mobilise power resources to influence changes at work.

Resting state BOLD-perfusion coupling patterns using multiband multi-echo pseudo-continuous arterial spin label imaging

The alteration of neurovascular coupling (NVC), where acute localized blood flow increases following neural activity, plays a key role in several neurovascular processes including aging and neurodegeneration. While not equivalent to NVC, the coupling between simultaneously measured cerebral blood flow (CBF) with arterial spin labeling (ASL) and blood oxygenation dependent (BOLD) signals, can also be affected. Moreover, the acquisition of BOLD data allows the assessment of resting state (RS) fMRI metrics. In this study a multiband, multi-echo (MBME) pseudo-continuous ASL (pCASL) sequence was used to collect simultaneous BOLD and ASL data in a group of healthy control subjects, and the patterns of BOLD-CBF coupling were evaluated. Coupling was also correlated with the BOLD RS measures. The variability, reproducibility, and reliability of the metrics were also computed in a multi-session subgroup. Areas of higher coupling were observed in the visual, motor, parietal, and frontal cortices and corresponded to major brain networks. Areas of significant correlation between coupling and BOLD RS measures corresponded to areas of heightened coupling. Higher variability and lower reliability were found for coupling metrics compared to BOLD RS metrics. These results indicate BOLD-CBF coupling metrics may be useful for studying neurovascular physiology.

Acral Melanoma: A Review of Its Pathogenesis, Progression, and Management.

Acral melanoma is a distinct subtype of cutaneous malignant melanoma that uniquely occurs on ultraviolet (UV)-shielded, glabrous skin of the palms, soles, and nail beds. While acral melanoma only accounts for 2-3% of all melanomas, it represents the most common subtype among darker-skinned, non-Caucasian individuals. Unlike other cutaneous melanomas, acral melanoma does not arise from UV radiation exposure and is accordingly associated with a relatively low tumor mutational burden. Recent advances in genomic, transcriptomic, and epigenomic sequencing have revealed genetic alterations unique to acral melanoma, including novel driver genes, high copy number variations, and complex chromosomal rearrangements. This review synthesizes the current knowledge on the clinical features, epidemiology, and treatment approaches for acral melanoma, with a focus on the genetic pathogenesis that gives rise to its unique tumor landscape. These findings highlight a need to deepen our genetic and molecular understanding to better target this challenging subtype of melanoma.

Accelerating Performance: Reliability of Phase-Specific Measurements in Elite Speed Skaters’ 100-Meter Starts

ABSTRACT This study examined within-session reliability and minimal detectable change (MDC) in mean split time, velocity, and acceleration across 100-meter start phases (0–20, 20–50, 50–70, 70–100 m) in elite speed skaters. Nineteen skaters (10 females, 9 males) completed two trials on the same day on a 400-meter indoor ice track under standardized conditions, with split times recorded every 10-meters using an automated timing system. Results showed acceptable reliability for mean split time (ICC = 0.84, CV = 7.5%, MDC = 0.00–0.15 s) and velocity (ICC = 0.79, CV = 9.2%, MDC = 0.21–1.09 m·s− 1). Mean acceleration showed moderate reliability (ICC = 0.70, CV = 12.4%) and higher variability over greater distances (70–100 m). These findings support using the 100-meter acceleration profile to assess key performance elements (initial start and sustained acceleration), emphasizing the need to tailor training and assessments to specific race phases.

Helminths infection of Schizothorax niger in Kashmir, India: morphological and molecular characterization.

The identification of helminth parasites in Schizothorax spp. from Kashmir, including Schyzocotyle acheilognathi, Pomphorhynchus kashmirensis, and Adenoscolex oreini, is hindered by morphological limitations and high intraspecific variation. While previous studies have relied on morphological diagnosis, a comprehensive molecular characterization is lacking. To address these limitations and achieve more accurate species identification, this study employs molecular techniques such as DNA sequencing and phylogenetic analysis. Genomic DNA was extracted using standardized protocols. Partial amplification of 18S, ITS, and 28S rRNA was carried out using specific primer sets, followed by Sanger sequencing. Genetic characteristics were analyzed using bioinformatic approaches, focusing on Nucleotide divergence and Phylogenetic relationships. Phylogenetic analysis confirmed the monophyly of S. acheilognathi, revealing close relationships with S. nayarensis. Interspecific variation ranged from 2.0 - 4.1% for 18S and 0.8 - 2.2% for 28S rDNA, while P. kashmirensis showed high genetic similarity to P. tereticollis and P. laevis with variations ranging from 0.1 - 1.5% for 18S and 2.3-6.0% for ITS rDNA. A. oreini forms a monophyletic lineage separate from Caryophyllaeides and Caryophyllaeus species. Our study resolved persistent taxonomic ambiguities within the order Bothriocephalidea, resulting in the reassignment of Schyzocotyle acheilognathi (previously Bothriocephalus acheilognathi) to the reinstated genus Schyzocotyle. This study underscores the utility of ribosomal gene sequencing in characterizing fish parasites and highlights the need for taxonomic re-evaluation of A. oreini within the Capingentidae family.

High-Frequency High-Magnetic Flux Variation Foil Winding AC Inductor Design with the Vertical Penetrating Magnetic Field Elimination

In traditional inductor design with planar windings, the magnetic field distribution may not be well-organized, leading to significant winding loss, particularly at high switching frequencies. This study explores the relationship between current distribution and magnetic field distribution in the winding region. Unlike conventional magnetic flux distribution, which directs a large portion of the magnetic field vertically through the windings in the winding region, this work introduces a structure that maintains most of the magnetic flux parallel to the foil windings through the application of quasi-distributed air gaps. This paper presents a design methodology for a high-frequency foil winding inductor with high flux variation. Building on this concept, a high-power density, low loss inductor with foil windings is designed based on the four-switch buck-boost (FSBB) converter. Experimental results demonstrate that the proposed inductor design significantly reduces winding loss in inductors with planar windings.

Ecohydrological Conditions in Urban Wells and Patterns of Invertebrate Fauna Distribution (Kraków, Poland)

ABSTRACTGroundwaters are threatened by various kinds of contaminants, especially in cities. The results of an ecohydrological analysis (hydrobiological, chemical and geological) conducted in 91 urban wells in Kraków showed their effect on fauna composition and abundance. In 74 wells, the presence of invertebrates, chiefly characteristic for surface water, as well as Collembola was stated. Copepoda were found in 40 wells, whereas Nematoda, Annelida and Diptera larvae were found at over a dozen sites. Microturbellaria, Rotifera, Ostracoda and Amphipoda were present in only a few wells. The aim of this article was to find the patterns of invertebrates' distribution in the wells to further understanding of their relationships with groundwater chemistry and the geological background. This is especially important in light of the anthropogenic pollution occurring in wells and the desired attainment of the good ecological status of groundwater. According to Student's t‐test, the presence of fauna did not depend on the studied environmental factors, whereas Pearson correlations showed that total fauna abundance and Copepoda occurrence positively correlated with water temperature which was higher in the city in comparison to that in rural wells. The value of the Shannon–Wiener index and the number of taxa negatively correlated with the well's depth. High variations of water chemical parameters caused by mixed lithology and hydrogeology as well as spotty contamination may affect the occurrence of fauna.

Health system and environmental factors affecting global progress towards achieving End TB targets between 2015 and 2020.

Health system and environmental factors play a significant role in achieving the World Health Organization (WHO) End Tuberculosis (TB) targets. However, quantitative measures are scarce or non-existent at a global level. We aimed to measure the progress made towards meeting the global End TB milestones from 2015 to 2020 and identify health system and environmental factors contributing to the success. We obtained data from ten different online data repositories and used principal component analysis to create domain-specific health system performance measures. We used radar charts and dumbbell plots to show the country's progress in ending TB with their health systems. Lastly, we used a linear regression model to identify key health systems and environmental predictors of the percent reduction in TB incidence and mortality. There was a high variation in TB incidence and mortality reduction between countries and WHO regions. Of all countries included, 75 (39.3%) achieved more than a 20% reduction in TB incidence between 2015 and 2020. However, only 31 (16.2%) reached a 35% reduction in TB mortality. The European Region achieved the highest incidence reduction, exceeding the 2020 milestone with a 25% reduction. The African Region also made notable progress, achieving an 18% mortality reduction despite its relatively poor health systems. Health system factors, such as TB financing, TB-specific health service delivery, access to medicine, and governance, were significantly associated with TB mortality reduction between 2015 and 2020. Environmental factors, such as average annual temperature and air particulate matter concentration, were found to have a significant negative effect on TB incidence and mortality reduction. Weak health systems were identified as major barriers to achieving the End TB milestones in most high-burden countries. Hence, strengthening health systems with a special focus on TB financing, service delivery, and access to medicine in these countries should be prioritised to achieve global TB mortality reduction targets. Countries should follow WHO's air quality guidelines and rapidly reduce carbon dioxide and other greenhouse gas emissions to mitigate the impact of environmental factors.

Analysis of income and risk of Porang farming

This research data analyzed quantitatively to find the amount of income and risk of farming. The research was conducted in Mundeh Kauh Village, West Selemadeg District, Tabanan Regency and Depeha Village, Kubu Additional District, Buleleng Regency. The samples were taken from 19 Porang farmers from members of the Maju Bersama farmer group using the saturated sampling method and 11 Porang farmers from the Bali Porang Farmers Association (P3B) using the accidental sampling method. Farming income is the difference between the farming income obtained and the total farming expenditure. Farming risk is analyzed using the coefficient of variation. The research results reveal the following. The average income of Porang farming in Bali is IDR 2,130,493.46 per production cycle with an average plant population of 2,155 plants. The risk of Porang farming is classified as a large risk as indicated by the coefficient of variation (CV) value of Porang farming income of 1.96 (>0.5). The source of risk in Porang farming is the high variation in production due to exposure to tuber caterpillar attacks and falling prices due to the closure of Indonesian Porang exports due to non-fulfillment of food safety requirements in importing countries.

Two-dimensional Czochralski growth of single-crystal MoS2.

Batch production of single-crystal two-dimensional (2D) transition metal dichalcogenides is one prerequisite for the fabrication of next-generation integrated circuits. Contemporary strategies for the wafer-scale high-quality crystallinity of 2D materials centre on merging unidirectionally aligned, differently sized domains. However, an imperfectly merged area with a translational lattice brings about a high defect density and low device uniformity, which restricts the application of the 2D materials. Here we establish a liquid-to-solid crystallization in 2D space that can rapidly grow a centimetre-scale single-crystal MoS2 domain with no grain boundaries. The large MoS2 single crystal obtained shows superb uniformity and high quality with an ultra-low defect density. A statistical analysis of field effect transistors fabricated from the MoS2 reveals a high device yield and minimal variation in mobility, positioning this FET as an advanced standard monolayer MoS2 device. This 2D Czochralski method has implications for fabricating high-quality and scalable 2D semiconductor materials and devices.