Core Length Research Articles

The Role of Multiparametric MRI and MRI–targeted Biopsy in the Diagnosis of Radiorecurrent Prostate Cancer: An Analysis from the FORECAST Trial

BackgroundThe role of multiparametric magnetic resonance imaging (MRI) for detecting recurrent prostate cancer after radiotherapy is unclear. ObjectiveTo evaluate MRI and MRI-targeted biopsies for detecting intraprostatic cancer recurrence and planning for salvage focal ablation. Design, setting, and participantsFOcal RECurrent Assessment and Salvage Treatment (FORECAST; NCT01883128) was a prospective cohort diagnostic study that recruited 181 patients with suspected radiorecurrence at six UK centres (2014 to 2018); 144 were included here. InterventionAll patients underwent MRI with 5 mm transperineal template mapping biopsies; 84 had additional MRI-targeted biopsies. MRI scans with Likert scores of 3 to 5 were deemed suspicious. Outcome measurements and statistical analysisFirst, the diagnostic accuracy of MRI was calculated. Second, the pathological characteristics of MRI-detected and MRI-undetected tumours were compared using the Wilcoxon rank sum test and chi-square test for trend. Third, four biopsy strategies involving an MRI-targeted biopsy alone and with systematic biopsies of one to two other quadrants were studied. Fisher’s exact test was used to compare MRI-targeted biopsy alone with the best other strategy for the number of patients with missed cancer and the number of patients with cancer harbouring additional tumours in unsampled quadrants. Analyses focused primarily on detecting cancer of any grade or length. Last, eligibility for focal therapy was evaluated for men with localised (≤T3bN0M0) radiorecurrent disease. Results and limitationsOf 144 patients, 111 (77%) had cancer detected on biopsy. MRI sensitivity and specificity at the patient level were 0.95 (95% confidence interval [CI] 0.92 to 0.99) and 0.21 (95% CI 0.07 to 0.35), respectively. At the prostate quadrant level, 258/576 (45%) quadrants had cancer detected on biopsy. Sensitivity and specificity were 0.66 (95% CI 0.59 to 0.73) and 0.54 (95% CI 0.46 to 0.62), respectively. At the quadrant level, compared with MRI-undetected tumours, MRI-detected tumours had longer maximum cancer core length (median difference 3 mm [7 vs 4 mm]; 95% CI 1 to 4 mm, p < 0.001) and a higher grade group (p = 0.002). Of the 84 men who also underwent an MRI-targeted biopsy, 73 (87%) had recurrent cancer diagnosed. Performing an MRI-targeted biopsy alone missed cancer in 5/73 patients (7%; 95% CI 3 to 15%); with additional systematic sampling of the other ipsilateral and contralateral posterior quadrants (strategy 4), 2/73 patients (3%; 95% CI 0 to 10%) would have had cancer missed (difference 4%; 95% CI –3 to 11%, p = 0.4). If an MRI-targeted biopsy alone was performed, 43/73 (59%; 95% CI 47 to 69%) patients with cancer would have harboured undetected additional tumours in unsampled quadrants. This reduced but only to 7/73 patients (10%; 95% CI 4 to 19%) with strategy 4 (difference 49%; 95% CI 36 to 62%, p < 0.0001). Of 73 patients, 43 (59%; 95% CI 47 to 69%) had localised radiorecurrent cancer suitable for a form of focal ablation. ConclusionsFor patients with recurrent prostate cancer after radiotherapy, MRI and MRI-targeted biopsy, with or without perilesional sampling, will diagnose cancer in the majority where present. MRI-undetected cancers, defined as Likert scores of 1 to 2, were found to be smaller and of lower grade. However, if salvage focal ablation is planned, an MRI-targeted biopsy alone is insufficient for prostate mapping; approximately three of five patients with recurrent cancer found on an MRI-targeted biopsy alone harboured further tumours in unsampled quadrants. Systematic sampling of the whole gland should be considered in addition to an MRI-targeted biopsy to capture both MRI-detected and MRI-undetected disease. Patient summaryAfter radiotherapy, magnetic resonance imaging (MRI) is accurate for detecting recurrent prostate cancer, with missed cancer being smaller and of lower grade. Targeting a biopsy to suspicious areas on MRI results in a diagnosis of cancer in most patients. However, for every five men who have recurrent cancer, this targeted approach would miss cancers elsewhere in the prostate in three of these men. If further focal treatment of the prostate is planned, random biopsies covering the whole prostate in addition to targeted biopsies should be considered so that tumours are not missed.

F18-DCFPyL PSMA-PET/CT vs. mpMRI for Localizing the Gross Target Volume for Radiotherapy in Prostate Cancer

Local recurrences in prostate cancer (Pca) after radiotherapy generally occur in the site of dominant tumor burden, and recent evidence based on multi parametric (mpMRI) supports tumor-targeted escalation of dose to improve biochemical disease-free survival outcomes. With the recent emergence of prostate cancer targeted radiotracers, we hypothesize that PSMA-PET and mpMRI may not equally depict the pathological gross target volume (pGTV) at risk of recurrence after radiotherapy. Subjects who underwent both mpMRI and 18F DCFPyl PSMA-PET/CT prior to radiotherapy were identified from a prospective REB-approved registry. Patients who were naive to radiotherapy and patients with local recurrences were evaluated. Each patient underwent standard of care systematic biopsies prior to imaging and treatment. Sextants from prostate biopsy were analyzed on an independent basis. Per previous published work, pGTV at risk of recurrence was defined as the pathological dominant lesions with peak PCL (percentage core length) involvement and any sextants with ≽ 40% PCL involvement. Each imaging method was analyzed independently to determine spatial correspondence of the visible tumor to pGTV at risk of recurrence. Lesions scored 4-5 (PIRADSv2.1) were identified on mpMRI. For PSMA-PET, regions with uptake higher than the adjacent background with scaling SUVmin-max 0-10 were identified. Forty-seven patients with histopathological proven intermediate to high-risk Pca represented the study cohort. Of the 320 sextants, 135 were involved with PCa. Thirty-six percent (17∕47) of patients had a history of prior radiotherapy. PSMA-PET identified the pGTV in 89% (42∕47) of patients, while mpMRI yielded a higher detection rate at 98% (46∕47) (89% vs 98% p = 0.038). The only pGTV not detected on mpMRI was also missed by PSMA-PET, and had received EBRT in 2011. Of the four other pGTVs at risk of recurrence missed by PSMA-PET, three had no history of prior radiotherapy and one was treated with brachytherapy in 2005. Overall, we found no differences in imaging detection rates between previously treated and untreated patients. More detailed volumetric analyses are ongoing and will be presented. mpMRI may provide superior detection of the pGTV at risk of recurrence in comparison to PSMA-PET. Until further research is completed, clinicians should exercise caution in omitting mpMRI and utilizing PSMA-PET as the sole imaging method for GTV targeting.

Precise tuning of silica pore length and pore diameter on silica-encapsulated gold core–shell nanoparticles and catalytic impact

The ability to individually tune the pore length and pore diameter of silica-encapsulated gold core–shell nanoparticles (CSNPs) via a seeded encapsulation method is demonstrated and their impact on catalysis determined. Reducing the solvent volume during the shell growth phase resulted in CSNPs with shells of increasing thickness from 75 nm to 202 nm, following a linear relationship. The addition of 1, 3, 5-triisopropylbenzene (TIB) during synthesis increased the average pore diameter from 25 Å to 32 Å by swelling the pore template, swelling further to 38 Å when adding both TIB and n-decane. By decoupling the gold core reduction and silica condensation stages, gold core diameters were largely unaffected by silica growth reaction conditions. This was achieved by encapsulating CTAB-stabilized nanoparticles rather than reducing and stabilizing the nanoparticles during silica condensation. When used to catalyze solvent-free benzyl alcohol oxidation, it was found that CSNPs with increasing shell thicknesses demonstrated increased formation of the desirable aldehyde product, holding the undesired ester product yield constant. In contrast, CSNPs with increasing pore diameter exhibit increased formation of both aldehyde and ester products unselectively. These results—uniquely observed through the parametric isolation of pore length and diameter—suggest the reactant concentration at the pore wall due to hydrogen bonding, forming concentric “microphases” within the pores.

An integrated, non-destructive method for evaluating core quality from R/V Legend’s giant piston coring system (LGD-GPC)

Despite technological advances, some core disturbances due to piston coring process still occur and can be extremely difficult to identify characteristics of sedimentary structures during qualitative visual core description and core lithologies. Few quantitative methods have offered plausible ways to define the exact magnitude of the distorted sedimentary structures in imperfect sedimentary records in the context of overly limited sedimentary records. In this study, an investigation was conducted on the Kaoping slope offshore southwestern Taiwan, a region known for its high sedimentation rate (> 0.9 g/cm2/year), using both the LGD-GPC (giant piston corer) and giant gravity corer techniques. To examine how GPC procedures have shaped the retrieval of sedimentary sequences and affected core quality, we apply well-developed, non-destructive analyses, including physical property measurements, visible color reflectance and digital core images with quantitative curvature index (CI), to recovered sediments. Cores at 22° 23′N, 120° 13′E were as the basis for non-destructive measurement comparison. Evidence from digital core imaging and the CI calculation further supports the mechanism of piston suction. We suggest that shear deformation of sediment against the core barrel would be the prominent factor that govern the observed core disturbances in LGD-GPC cores. Meanwhile, excessive pulling forcing from a modified TORI piston and a slowly lift speed during LGD-GPC coring process may further aggravate core disturbances at the revisited site. The sedimentary length of core LGD-T43-B-PC is overestimated by more than 200%. We further demonstrate that an integration of the CI and color reflectance is an effective way to evaluate the transformation and distorted sedimentary sequences.

Numerical analysis on the effect of passive control geometry in supersonic jet mixing enhancement

Abstract This paper presents the numerical analysis of a convergent-divergent circular nozzle with the exit Mach number of 1.69 with and without passive control at the exit. The passive control method opted for this analysis was inward and outward ascending triangular protrusion. This paper explores the influence of the passive control geometry and its blockage area concerning the nozzle exit. The nozzle pressure ratio (NPR) used for carrying out the flow analysis were 3, 4.932, and 6. Two different inward and outward protrusions were used with a height of 1.5 mm and 3 mm. From the results, the potential core length of the protrusion 1.5 mm height was not much changed in the both outward and inward cases. But when the height of the protrusion was increased to 3 mm, there was a noticeable core length reduction at all NPR but with different cases. At the NPR of 6, the potential core length of the inward protrusions 3 mm was reduced by 44 % compared to the plain CD nozzle.

Is prostatic adenocarcinoma with cribriform architecture more difficult to detect on prostate MRI?

Cribriform (CBFM) pattern on prostate biopsy has been implicated as a predictor for high-risk features, potentially leading to adverse outcomes after definitive treatment. This study aims to investigate whether the CBFM pattern containing prostate cancers (PCa) were associated with false negativemagnetic resonance imaging (MRI) and determine the association between MRI and histopathological disease burden. Patients who underwent multiparametric magnetic resonance imaging (mpMRI), combined 12-core transrectal ultrasound (TRUS) guided systematic (SB) and MRI/US fusion-guided biopsy were retrospectively queried for the presence of CBFM pattern at biopsy. Biopsy cores and lesions were categorized as follows: C0 = benign, C1 = PCa with no CBFM pattern, C2 = PCa with CBFM pattern. Correlation between cancer core length (CCL) and measured MRI lesion dimension were assessed using a modified Pearson correlation test for clustered data. Differences between the biopsy core groups were assessed with the Wilcoxon-signed rank test with clustering. Between 2015 and 2022, a total of 131 consecutive patients with CBFM pattern on prostate biopsy and pre-biopsy mpMRI were included. Clinical feature analysis included 1572 systematic biopsy cores (1149 C0, 272 C1, 151 C2) and 736 MRI-targeted biopsy cores (253 C0, 272 C1, 211 C2). Of the 131 patients with confirmed CBFM pathology, targeted biopsy (TBx) alone identified CBFM in 76.3% (100/131) of patients and detected PCa in 97.7% (128/131) patients. SBx biopsy alone detected CBFM in 61.1% (80/131) of patients and PCa in 90.8% (119/131) patients. TBx and SBx had equivalent detection in patients with smaller prostates (p = 0.045). For both PCa lesion groups there was a positive and significant correlation between maximum MRI lesion dimension and CCL (C1 lesions: p < 0.01, C2 lesions: p < 0.001). There was a significant difference in CCL between C1 and C2 lesions for T2 scores of 3 and 5 (p ≤ 0.01, p ≤ 0.01, respectively) and PI-RADS 5 lesions (p ≤ 0.01), with C2 lesions having larger CCL, despite no significant difference in MRI lesion dimension. The extent of disease for CBFM-containing tumors is difficult to capture on mpMRI. When comparing MRI lesions of similar dimensions and PIRADS scores, CBFM-containing tumors appear to have larger cancer yield on biopsy. Proper staging and planning of therapeutic interventions is reliant on accurate mpMRI estimation. Special considerations should be taken for patients with CBFM pattern on prostate biopsy.

Focal therapy versus radical prostatectomy and external beam radiotherapy as primary treatment options for non-metastatic prostate cancer: results of a cost-effectiveness analysis

AimsFocal therapy treats individual areas of tumour in non-metastatic prostate cancer in patients unsuitable for active surveillance. The aim of this work was to evaluate the cost-effectiveness of focal therapy versus prostatectomy and external beam radiotherapy (EBRT).Materials and methodsA Markov cohort health state transition model with four health states (stable disease, local recurrence, metastatic disease and death) was created, evaluating costs and utilities over a 10-year time horizon for patients diagnosed with non-metastatic prostate cancer. National Health Service (NHS) for England perspective was used, based on direct healthcare costs. Clinical transition probabilities were derived from prostate cancer registries in patients undergoing radical prostatectomy, EBRT and focal therapy using cryotherapy (Boston Scientific) or high-intensity focused ultrasound (HIFU) (Sonablate). Propensity score matching was used to ensure that at-risk populations were comparable. Variables included age, prostate-specific antigen (PSA), International Society of Urological Pathology (ISUP) grade group, maximum cancer core length (mm), T-stage and year of treatment.ResultsFocal therapy was associated with a lower overall cost and higher quality-adjusted life year (QALY) gains than either prostatectomy or EBRT, dominating both treatment strategies. Positive incremental net monetary benefit (NMB) values confirm focal therapy as cost-effective versus the alternatives at a willingness to pay (WTP) threshold of £30,000/QALY. One-way deterministic sensitivity analyses revealed consistent results.LimitationsData used to calculate the transition probabilities were derived from a limited number of hospitals meaning that other potential treatment options were excluded. Limited data were available on later outcomes and none on quality of life data, therefore, literature-based estimates were used.ConclusionsCost-effectiveness modelling demonstrates use of focal therapy (cryotherapy or HIFU) is associated with greater QALY gains at a lower overall cost than either radical prostatectomy or EBRT, representing good value for money in the NHS.

Optimization of Oxygen Injection Conditions with Different Molten Steel Levels in the EAF Refining Process by CFD Simulation

In electric arc furnace (EAF) steelmaking, oxygen jets play a crucial role in controlling stirring ability, chemical reactions, and energy consumption. During the EAF lifetime, refractory wear leads to a decrease in the molten steel level and an increase in the nozzle-to-steel distance, thereby negatively affecting the overall energy efficiency of the process. The objective of this study is to optimize the energy efficiency of the EAF refining process by adjusting the nozzle flow conditions and conducting an analysis of jet performance using computational fluid dynamics (CFD) simulation. Three types of injection jets were considered: the conventional jet, the CH4 coherent jet, and the CH4 + O2 coherent jet. The findings reveal that the shrouded flame of the coherent jet enhances jet performance by maintaining the maximum velocity, extending the potential core length, and increasing the penetration depth in the molten steel bath. To maintain the jet performance in response to an increased nozzle-to-steel distance resulting from refractory wear, transitions from the conventional jet to the CH4 coherent jet and the CH4 + O2 coherent jet are recommended once the nozzle-to-steel distance increases from its initial level of 1000 mm to 1500 mm and 2000 mm, respectively.

A FEM-Based Comparative Study of the Effect of Rotor Bar Designs on the Performance of Squirrel Cage Induction Motors

Induction motors (IM) are the most frequently used type of motor in the industry. The number of rotor slots, bar geometry, and conductivity of bar material have a strong impact on the torque profile and efficiency characteristics of induction motors. This study focused on investigating the effect of different rotor bar designs on motor performance by the finite element method (FEM). The IMs have been designed using the same stator core, winding, and core lengths. The total rotor bar cross-section areas are also fixed throughout all designs. In addition to the change in the number of rotor bars and geometry, the effect of copper and aluminum bar materials on motor performance was also investigated, both for single and double-layered squirrel-cage structures. The results of the study indicate that the starting torque of the motor in a 36/30-slot aluminum single-cage structure was obtained as 96.26 Nm, while the starting torque of a 36/46-slot aluminum double-cage structure was found to be 115.34 Nm. It is also found that the starting torque of the initial design can be increased by up to 19.82% by changing only the rotor bar numbers and material with the same stator and rotor size. The efficiency of the motors was determined as 86.6% for both designs. In addition to efficiency, the output torque ripple has been decreased to 2.63, which equals a 67.32% decrease in the ripple of the initial design. The improved design has an approximately 8 °C lower T2 due to better cooling performance as a result of a higher number of rotor slots.

Transperineal vs transrectal magnetic resonance and ultrasound image fusion prostate biopsy: a pair-matched comparison

The objective of this study was to compare transperineal (TP) versus transrectal (TR) magnetic resonance imaging (MRI) and transrectal ultrasound (TRUS) fusion prostate biopsy (PBx). Consecutive men who underwent prostate MRI followed by a systematic biopsy. Additional target biopsies were performed from Prostate Imaging Reporting & Data System (PIRADS) 3–5 lesions. Men who underwent TP PBx were matched 1:2 with a synchronous cohort undergoing TR PBx by PSA, Prostate volume (PV) and PIRADS score. Endpoint of the study was the detection of clinically significant prostate cancer (CSPCa; Grade Group ≥ 2). Univariate and multivariable analyses were performed. Results were considered statistically significant if p < 0.05. Overall, 504 patients met the inclusion criteria. A total of 168 TP PBx were pair-matched to 336 TR PBx patients. Baseline demographics and imaging characteristics were similar between the groups. Per patient, the CSPCa detection was 2.1% vs 6.3% (p = 0.4) for PIRADS 1–2, and 59% vs 60% (p = 0.9) for PIRADS 3–5, on TP vs TR PBx, respectively. Per lesion, the CSPCa detection for PIRADS 3 (21% vs 16%; p = 0.4), PIRADS 4 (51% vs 44%; p = 0.8) and PIRADS 5 (76% vs 84%; p = 0.3) was similar for TP vs TR PBx, respectively. However, the TP PBx showed a longer maximum cancer core length (11 vs 9 mm; p = 0.02) and higher cancer core involvement (83% vs 65%; p < 0.001) than TR PBx. Independent predictors for CSPCa detection were age, PSA, PV, abnormal digital rectal examination findings, and PIRADS 3–5. Our study demonstrated transperineal MRI/TRUS fusion PBx provides similar CSPCa detection, with larger prostate cancer core length and percent of core involvement, than transrectal PBx.

Enhanced production of highly methylated brGDGTs linked to anaerobic bacteria from sediments of the Mariana Trench

Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial membrane lipids that are widely used in terrestrial paleoclimatic reconstructions. Recent studies have reported that brGDGTs can also be produced by marine bacteria. However, the environmental factors influencing marine-derived brGDGTs and their source organisms remain largely unknown. Here, we investigated the distribution and composition of brGDGTs and a suite of their putative derivatives called overly branched GDGTs (obGDGTs) in the Mariana Trench core sediments (water depth 8300 m, core length 320 cm), as well as the composition of bacterial communities. The ratio of the branched over isoprenoid tetraethers (BIT) was 0.03-0.21 (average 0.07; SD = 0.04; n = 21) and the ratio ΣIIIa/ΣIIa of brGDGTs was 0.93-7.47 (average 3.39; SD = 1.73; n = 21), which support the in situ production of brGDGTs. Co-occurrence network analysis revealed that a total of 33 types of bacteria at the order level (e.g., Armatimonadota DG-56, Proteobacteria Rhodospirillales, Chloroflexi SAR202_clade) were closely related to the distribution of brGDGTs and obGDGTs, which could be potential sources for these compounds. The abrupt increase in brGDGT and obGDGT concentrations in deeper oxygen-depleted sediments and their good correlations with anaerobic bacterial abundances suggest that these brGDGTs and obGDGTs may be produced by anaerobic bacteria residing in the anoxic sediments. Considerable variation in the degrees of methylation and cyclization of brGDGTs (obGDGTs) under different redox conditions indicate that sediment oxygen levels may have a profound impact on the presence and abundance of brGDGTs and obGDGTs, which should be considered when applying them for paleo-temperature or pH reconstructions. This study shows that brGDGTs and obGDGTs obtained from the Mariana Trench were probably produced by a variety of bacterial phyla indigenous in the hadal ocean, which are different from Acidobacteria commonly considered to be major terrestrial sources of brGDGTs.

Infrared spectroscopy and chemometric modelling of organic carbon measured by Rock-Eval pyrolysis of UK shale rock

Abstract Shale rock core from the Bowland Shale Formation, UK, was analysed in the laboratory using Rock-Eval pyrolysis and Fourier transform infrared spectroscopy (FTIR). These methods are used to characterize the organic constituents of soil and rock. This research is a proof-of-concept study to investigate whether regression models developed using FTIR and Rock-Eval data for the same length of core can be used to estimate selected Rock-Eval parameters. The accuracy of the regression models was assessed using statistical methods, the results of which were used to choose preferred models for each Rock-Eval parameter. The models produced were shown to have an acceptable level of uncertainty for total organic carbon and S1, S2 and S3 outputs, which led us to conclude that these are potentially suitable for estimating unknown down-core Rock-Eval parameter values. Conversely, the model for the temperature of the maximum rate of hydrocarbon generation ( T max ) had higher variability in the cross-validation data above the acceptable level of uncertainty, which could lead to erroneous estimates. Down-core interpolations of selected Rock-Eval parameters could be practically achieved by modelling FTIR data by maintaining standard sample frequencies for Rock-Eval while supplementing with higher frequencies for FTIR and chemometric analysis.

Dynamic time warping to quantify age distortion in firn cores impacted by melt processes

Abstract As warming intensifies across the Greenland ice sheet, an increasing number of shallow coring and radar studies are targeting the melt-impacted firn column to investigate meltwater processes. Highly inhomogeneous infiltration and refreezing, however, redistributes mass, distorting age–depth relationships and confounding comparisons between different cores. Here, we utilize a dynamic time warping algorithm for time series alignment to investigate and quantify the heterogeneous impact of melt processes on nine closely spaced (within 50 m) firn core-density profiles. The 10 m cores were collected relatively high in Greenland's percolation zone, where melt alteration is minimal compared to lower elevation. Our analysis demonstrates the effectiveness of dynamic time warping as a tool for assessing heterogeneity between ice core records. We find that the optimal alignment of density profiles in the nine cores requires vertical stretching and compression of individual profiles, ranging from, on average, &lt;1 to ~16% of the core lengths. We identified four depth zones of mass redistribution that appear to coincide with observed ice layers. Further, ~75% of density measurements from each core do not align with an age model-derived density profile that assumes no mass redistribution of meltwater, indicating the pervasive impact of melt processes.

Evaluating the Learning Curve for In-office Freehand Cognitive Fusion Transperineal Prostate Biopsy

To define the learning curve of the in-office, freehand MRI-ultrasound cognitive fusion transperineal prostate biopsy (CTPB) by assessing cancer detection, biopsy core quantity and quality, procedure times, and complications over the initial experience. We reviewed 110 consecutive CTPB performed March 2021-September 2022 by a urologist inexperienced with the PrecisionPoint platform. The study period was divided into quarters to assess for temporal variation in outcomes. Univariable and multivariable analysis modeled the learning curve. Across quarters, there were no differences in the detection of clinically significant prostate cancer (Q1:50%, Q2:52%, Q3:50%, Q4:48%, P>.9) or Gleason grade group upgrading by targeted vs systematic biopsy (P=.6). Median procedure times improved with experience (Q1:17minutes, Q2:14minutes, Q3:12minutes, Q4:13minutes, P=.018). On multivariable analysis, procedure times decreased by 1minute per 20 cases (P<.001). On linear regression, CTPB procedure times approximated transrectal biopsy times after 90 cases (P<.001). The histopathologic core quality did not differ, as evidenced by consistent core length (P=.13) and presence of minimal fibromuscular tissue (P>.9). The most common complications, hematuria and hematospermia, were similar across quarters (P=.7, P=.3, respectively). There was a single episode of urinary retention and no reported infections. There is no evidence of a learning curve for CTPB as shown by consistent clinically significant prostate cancer detection, high-quality biopsy cores, and low complications. However, CTPB procedural times begin to approximate cognitive targeted transrectal biopsy times after 90 cases.

Experimental and numerical simulation research on counter-current imbibition distance in tight oil reservoirs

Counter-current imbibition behavior is an important mechanism for exploiting oil recovery during shut-in periods after hydraulic fracturing in tight oil reservoirs. However, most researches mainly focused on imbibition recovery and its influencing factors in tight oil reservoirs, while experimental investigations to quantitatively characterize the imbibition distance is still inadequate. In this work, counter-current imbibition experiments under one end open (OEO) boundary condition were conducted, and the dynamic imbibition process in porous media were monitored in real-time by nuclear magnetic resonance (NMR) pulse sequences and NMR imaging to quantify the range of counter-current imbibition and the reduction of oil saturation in-situ. In addition, a one-dimensional (1D) imbibition numerical model with OEO boundary condition at core scale was developed, and the influencing factors on oil production was further discussed in detail. The experimental results illustrated that the overall oil recoveries of nanofluid and deionized (DI) water were 25.37 % and 5.19 %, respectively. Moreover, the advancing distance of nanofluid was 4.44 cm, while DI water advanced only 2.38 cm along the core sample. Nanofluid considerably reduced residual oil saturation and increased movable fluid saturation, making the crude oil to be highly mobilized in micro- and mesopores. The simulated results well verified the counter-current imbibition experimental data, and indicated that the influences of core permeability and fluid viscosity on imbibition performances were more significant than that of core length. The purpose of this work is to provide a new method to determine the extent of counter-current imbibition.

Computational characterization of the temperature field in coaxial nitrogen injection under supercritical conditions

The modeling of fluids in the supercritical regime is addressed at conditions characteristic of liquid-propelled rocket engines, whose increasing performance demands paved the way for supercritical conditions. In the present document, nitrogen is used as a surrogate for the commonly encountered oxygen-hydrogen mixture so that turbulence mixing can be looked into without influences from combustion and chemically reacting effects. The temperature field validation on nitrogen coaxial injection at supercritical conditions, with high-velocity ratios (outer-to-inner), where the main (inner) stream is recessed relative to the outer stream, is of paramount importance in the flame stabilization operation of liquid rocket motors. The temperature field is analyzed taking into account varying momentum and velocity ratios, whose increased leads to a reduction of potential core lengths, increasing jet spreading. The results also depict a fundamental influence of thermal effects, dominating over the transport of momentum. The experimental data and large eddy simulation solvers from the literature agree with the estimate of injection velocities at several conditions and comparable to the space shuttle main engine pre-burner.

Multi physical comprehensive design of a new type of FeCo based high speed permanent magnet motor

In order to solve the problem that the design of high-speed permanent magnet motor (HSPMM) is constrained by multi-physical fields, this paper starts with the comprehensive study of multi physical fields, introduces the finite element calculation model of rotor strength-rotor dynamics-electromagnetic field-fluid field and temperature field, carries out the comprehensive design of a 100 kW, 18 000 r/min FeCo based HSPMM, and gives the detailed and complete research process of the main parameters of HSPMM under multi-physical field constraints. First, the initial dimensions of the motor are obtained by electromagnetic and mechanical design theory. Secondly, the influence of design parameters on rotor stress is analyzed in detail, including the influence of bearing rigidity, impeller mass, rotor diameter, rotor core length and gyroscopic effect on critical speed. Subsequently, the electromagnetic characteristics of the motor are comprehensively studied, the cooling system is designed in the Flow-Heat coupling calculation model and the temperature field is studied. Finally, the prototype test verifies the correctness and validity of the comprehensive research method of multi physical field.

Research on the Gas-Liquid Two-Phase Distribution Behavior and Influencing Factors of Swirling Flow in Horizontal Pipe

Gas-liquid two-phase swirling flow is widely used for gas-liquid separation in the power, chemical, petroleum, and nuclear industries. However, the majority of current research on swirling flow focuses on identifying flow patterns and does not pay more attention to topics such as the boundary where swirling flow forms. The length and diameter of the central gas core are the main focus of the current studies as well as the distribution patterns of gas-liquid two-phase. Comparative studies on the gas-liquid distribution morphology, such as whether the gas phase is separated and the separation mode, are lacking. In this paper, a combination of visual experimental observations and numerical simulations of Computational Fluid Dynamics (CFD) is used to investigate the formation conditions of gas-liquid two-phase swirling flow in three types of cyclonic components. The results show that the minimum superficial liquid velocity for the formation of swirling flow in the horizontal tube is about 0.375~0.82 m/s when the superficial gas velocity is less than 10 m/s. The formation of swirling flow is almost independent of the geometric swirl number and superficial liquid velocity when the superficial gas velocity is greater than 10 m/s. At low inlet superficial velocities, the tangential velocity determines the transition from swirling flow to stratified flow. However, at higher inlet superficial velocities, the decay of the cyclonic field is mainly affected by the wave amplitude of the gas-liquid interface. In both co-current and counter-current horizontal inline gas-liquid cyclone separators, the flow split is related to the vortex core breakdown of the central gas core. In addition, the numerical simulation results show that the breakdown of the vortex core is related to the pressure distribution inside the separator. This work enriches the study of swirling flow and provides a basis for the performance improvement of inline gas-liquid cyclone separators.

Numerical analysis of load-transfer mechanism of stiffened deep cement mixing pile foundation

ABSTRACT To reveal the load-transfer mechanism of stiffened deep cement mixing (SDCM) piles, the three-dimensional numerical analysis of a pilot pile was first conducted using the finite element software Diana, which can simulate the Mohr-Coulomb friction interface. Comparisons show that the computed load-settlement curve and distribution law of the skin frictions agreed well with the measurements. Then, the numerical method was employed to model the group pile foundations with four SDCM piles. It shows that the bearing capacity increased with increasing pile spacing and core lengths. And most loading was shared by the stiffened cores. It indicates that negative skin frictions may arise at the bottom of a reinforced concrete pile cap or the end of a stiffened core. And there is a hysteresis effect for the peak frictions on the two interfaces to mobilize. Meanwhile, plastic shear zones in soil and DCM pile may sequentially arise with increasing load.

Correlation, Genetic Variability, Heritability And Genetic Advance For Some Morphological Traits In Red Cabbage Lines (Brassica oleracea L.var. capitata subvar. rubra)

Genetic variability, heritability, genetic advance, genetic gain and correlation for seven different traits were studied in 22 genotypes of red cabbage. The genotypes were evaluated for seven quantitative characters such as head weight, head diameter, head length, core length, head volume, head density and head shape index. Analysis of variance showed significant variation among the genotypes for all the studied yield and yield contributing characters. Head weight of the lines was highly significant positively correlated with head length, head diameter, core length and head volume. The phenotypic coefficient of variation were observed to be higher than the corresponding genotypic coefficient of variation for all the characters studied, indicated that the traits were influenced by environment. The high phenotypic and genotypic coefficient (PCV and GCV) was observed for head density (30.61 and 20.06) followed by head volume (24.72 and 20.49), core length (15.68 and 14.99) and head weight (10.66 and 9.65). Heritability was high for majority of the traits. High heritability (broad sense) values were recorded for traits such as for head length (91.56%), core length (91.38%) and head diameter (82.24%). The highest genetic advance as percent of mean was shown by head volume (35.0 %) followed by core length (29.52%) and head density (27.09%). As a result, high heritability coupled with high genetic advance was observed head length, head diameter, head volume and head density which are governed by additive gene and could be effectively used as selection criteria in the breeding programme of red cabbage varieties with high yield.