Utility of plasma D-dimer for diagnosis of venous thromboembolism after hepatectomy

BACKGROUND Venous thromboembolism(VTE)is a potentially fatal complication of hepatectomy.The use of postoperative prophylactic anticoagulation in patients who have undergone hepatectomy is controversial because of the risk of postoperative bleeding.Therefore,we hypothesized that monitoring plasma D-dimer could be useful in the early diagnosis of VTE after hepatectomy.AIM To evaluate the utility of monitoring plasma D-dimer levels in the early diagnosis of VTE after hepatectomy.METHODS The medical records of patients who underwent hepatectomy at our institution between January 2017 and December 2020 were retrospectively analyzed.Patients were divided into two groups according to whether or not they developed VTE after hepatectomy,as diagnosed by contrast-enhanced computed tomography and/or ultrasonography of the lower extremities.Clinicopathological factors,including demographic data and perioperative D-dimer values,were compared between the two groups.Receiver operating characteristic curve analysis was performed to determine the D-dimer cutoff value.Univariate and multivariate analyses were performed using logistic regression analysis to identify significant predictors.RESULTS In total,234 patients who underwent hepatectomy were,of whom(5.6%)were diagnosed with VTE following hepatectomy.A comparison between the two groups showed significant differences in operative time(529 vs 403 min,P=0.0274)and blood loss(530 vs 138 mL,P=0.0067).The D-dimer levels on postoperative days(POD)1,3,5,7 were significantly higher in the VTE group than in the non-VTE group.In the multivariate analysis,intraoperative blood loss of>275 mL[odds ratio(OR)=5.32,95%confidence interval(CI):1.05-27.0,P=0.044]and plasma D-dimer levels on POD 5≥21μg/mL(OR=10.1,95%CI:2.04-50.1,P=0.0046)were independent risk factors for VTE after hepatectomy.CONCLUSION Monitoring of plasma D-dimer levels after hepatectomy is useful for early diagnosis of VTE and may avoid routine prophylactic anticoagulation in the postoperative period.

Elevated preoperative plasma D-dimer dose not adversely affect survival of gastric cancer after gastrectomy with curative intent: A propensity score analysis

Objective： Elevated plasma D-dimer has been reported to be associated with advanced tumor stage and poor survival in several types of malignancies. The purpose of this study was to assess the potential impact of preoperative plasma D-dimer level（PDL） on overall survival（OS） of gastric cancer（GC） patients undergoing curative surgery by applying propensity score analysis.Methods： A total of 1,025 curatively resected GC patients in Tianjin Medical University Cancer Institute ＆Hospital were enrolled. Patients were categorized into two groups based on preoperative PDL： the elevated group（EG） and the normal group（NG）. To overcome bias due to the different distribution of covariates for the two groups, a one-to-one match was applied using propensity score analysis, after matching, prognostic factors were analyzed.Results： In analysis for the whole study series, patients in the EG were more likely to have a larger proportion of tumor size ≥5 cm（67.5% vs. 55.8%, P=0.006）, elder mean age（64.0±10.8 years vs. 60.5±11.6 years, P〈0.001） and advanced tumor（T）, node（N）, and TNM stage. Patients with elevated PDL demonstrated a significantly lower 5-year OS than those with normal PDL（27.0% vs. 42.6%, P〈0.001）, however, the PDL was not an independent prognostic factor for OS in multivariate analysis [hazard ratio： 1.13, 95% confidence interval（95% CI）： 0.92–1.39,P=0.236]. After matching, 163 patients in the EG and 163 patients in the NG had the same characteristics. The 5-year OS rate for patients in the EG was 27.0% compared with 25.8% for those in the NG（P=0.809, log-rank）.Conclusions： The poor prognosis of GC patients with elevated preoperative PDL was due to the advanced tumor stage and elder age rather than the elevated D-dimer itself.

CLINICAL SIGNIFICANCE OF PLASMA D-DIMER LEVELS IN PATIENTS WITH ESOPHAGEAL CANCER

Objective: To investigate the clinical significance of the changes of D-dimer levels in patients with esophageal cancer. Methods: The plasma levels of D-dimer were measured pre-and postoperatively in 33 patients with esophageal cancer and 30 healthy subjects served as controls by the method of quantitative enzyme-linked immunosorbent assay (ELISA). Results: The mean preoperative plasma levels of D-dimer in the patients with esophageal cancer (1.98 mg/L±0.34 mg/L) were significantly higher than that of controls (0.33 mg/L±0.12 mg/L) (P<0.01). The D-dimer levels were remarkably elevated on the 1st day after operation (2.41 mg/L±0.55 mg/L) (P<0.01). On the 3rd day the level of D-dimer began to stepwise descend and on the 14th day near to control. The preoperative levels of D-dimer were significantly correlated with the tumor size but had no association with tumor location. A stepwise increase in the mean DD levels was found with the tumor stage. Conclusion: The hypercoagulation and fibrinolysis have occurred in patients with esophageal cancer. The operative trauma could enhance the fibrinolysis in the patients with esophageal cancer. The measurement of the preoperative DD levels is considered to be useful for the preoperative staging of esophageal cancer.

The relationship between level of plasma D-dimer and survival time in metastatic gastric cancer patients

Objective:The principal purpose of this study was to determine the relationship between level of plasma D-dimer and survival time in metastatic gastric cancer patients.Methods:We retrospectively collected the data of plasma D-dimer in metastatic gastric cancer patients admitted in our Department (Department of Oncology,The Affiliated Changzheng Hospital,The Second Military Medical University,Shanghai,China) from October 2006 to October 2008 and analyzed the relationship between level of plasma D-dimer and survival time along with other clinicopathologic parameters.Results:A total of 82 patients were studied in our research,52 were males and 30 females,and the mean age was 57 years.The 48 cases had a normal plasma D-dimer level (<300μg/L) and 34 had a high plasma D-dimer level (≥300μg/L).In the normal and high plasma D-dimer level groups,the mean survival times were 10.9 (95% CI:9.8-12.2) months and 6.8(95% CI:4.4-7.6) months respectively,and the difference was statistically significant.Conclusion:Metastatic gastric cancer patients with high plasma D-dimer level had significantly shorter survival time than those with normal plasma D-dimer level.Level of plasma D-dimer can be referred as a potential predictor in metastatic gastric cancer patients.

Plasma D-dimer level in early and late-onset neonatal sepsis

BACKGROUND Neonatal sepsis is a life-threatening disease.Early diagnosis is essential,but no single marker of infection has been identified.Sepsis activates a coagulation cascade with simultaneous production of the D-dimers due to lysis of fibrin.Ddimer test reflects the activation of the coagulation system.AIM To assess the D-dimer plasma level,elaborating its clinicopathological value in neonates with early-onset and late-onset neonatal sepsis.METHODS The study was a prospective cross-sectional study that included ninety neonates;divided into three groups:Group I:Early-onset sepsis(EOS);Group II:Late-onset sepsis(LOS);and GroupⅢ:Control group.We diagnosed neonatal sepsis according to our protocol.C-reactive protein(CRP)and D-dimer assays were compared between EOS and LOS and correlated to the causative microbiological agents.RESULTS D-dimer was significantly higher in septic groups with a considerably higher number of cases with positive D-dimer.Neonates with LOS had substantially higher levels of D-dimer than EOS,with no significant differences in CRP.Neonates with LOS had a significantly longer hospitalization duration and higher gram-negative bacteriemia and mortality rates than EOS(P<0.01).Gramnegative bacteria have the highest D-dimer levels(Acinetobacter,Klebsiella,and Pseudomonas)and CRP(Serratia,Klebsiella,and Pseudomonas);while gram-positive sepsis was associated with relatively lower levels.D-dimer had a significant negative correlation with hemoglobin level and platelet count;and a significant positive correlation with CRP,hospitalization duration,and mortality rates.The best-suggested cut-off point for D-dimer in neonatal sepsis was 0.75 mg/L,giving a sensitivity of 72.7%and specificity of 86.7%.The D-dimer assay has specificity and sensitivity comparable to CRP in the current study.CONCLUSION The current study revealed a significant diagnostic value for D-dimer in neonatal sepsis.D-dimer can be used as an adjunct to other sepsis markers to increase the sensitivity and specificity of diagnosing neonatal sepsis.

Estimation and Assessment of Plasma D-Dimer Levels in HIV Patients

Background: The elevation of plasma D-dimer levels is fully described and associated with the increase of the mortality of patients with HIV. The present study was aimed to estimate and assess the plasma D-dimer levels in HIV patient. Material and Methods: A case control study done in May 2015. A total of 100 subjects were enrolled in this study;50 were patients professionally diagnosed by HIV;25 (50%) were males and 25 (50%) were females;their mean age is 35 years. Further 50 normal healthy individuals as normal control group: their gender and age were matched with patient groups. The platelets poor plasma (PPP) was immediately prepared from citrated blood, then the plasma D-dimer level was measured using (MISPA-i2 Reagent) Switzerland. Data were analyzed using statistical packing for social sciences program (SPSS) 20. Results: The D-dimer levels was significantly higher in patient with HIV compared with the normal healthy control group (Mean and STD 502.2 ± 287.8 vs 251.8 ± 152.7 P. value 0.01). Conclusion: The D-dimer level was significantly higher in patient with HIV compared with those in normal healthy control group.

Analysis of the Role of D-Dimer,Interleukin-6,and Interleukin-18 in Differential Diagnosis of Pediatric Refractory Mycoplasma pneumoniae Pneumonia

Objective:To analyze the value of D-dimer(D-D),interleukin-6(IL-6),and IL-18 in the differential diagnosis of children with refractory Mycoplasma pneumoniae pneumonia(RMPP).Methods:The medical records of 92 children with Mycoplasma pneumoniae pneumonia(MPP)treated in the hospital were selected for retrospective analysis from January 2023 to January 2024.After comprehensive examinations such as computed tomography examination of the chest,48 children with general Mycoplasma pneumoniae pneumonia(GMPP)were put in the GMPP group and 44 children with RMPP were grouped in the RMPP group.The IL-6,IL-18,and D-D levels were compared between the two groups,and the receiver operating characteristic(ROC)curves were plotted to analyze their value for differential diagnosis of RMPP.Results:The levels of IL-6,IL-18,and D-D in the RMPP group were higher than those in the GMPP group(P<0.05);the ROC curves showed that the specificity of the differential diagnosis of IL-6,IL-18,and D-D was higher,and their diagnostic value was significant.Conclusion:Determination of IL-6,IL-18,and D-D levels in children with MPP can further diagnose the children’s condition,which can help physicians formulate targeted treatment plans,and is of great significance to the improvement of the children’s condition,which is worthy of attention.

Study of plasma parameters of coaxial plasma source using triple Langmuir probe and Faraday cup diagnostics

Coaxial plasma guns are a type of plasma source that produces plasma which propagates radially and axially controlled by the shape of the ground electrode, which has attracted much interest in several applications. In this work, a 120° opening angle of CPG nozzle is used as a plasma gun configuration that operates at the energy of 150 J. The ionization of polyethylene insulator between the electrodes of the gun produces a cloud of hydrogen and carbon plasma.The triple Langmuir probe and Faraday cup are used to measure plasma density and plasma temperature. These methods are used to measure the on-axis and off-axis plasma divergence of the coaxial plasma gun. The peak values of ion densities measured at a distance of 25 mm on-axis from the plasma gun are(1.6±0.5)×10^(19)m^(-3)and(2.8±0.6)×10^(19)m^(-3)for hydrogen and carbon plasma respectively and the peak temperature is 3.02±0.5 eV. The mean propagation velocity of plasma is calculated using the transit times of plasma at different distances from the plasma gun and is found to be 4.54±0.25 cm/μs and 1.81±0.18 cm/μs for hydrogen and carbon plasma respectively. The Debye radius is obtained from the measured experimental data that satisfies the thin sheath approximation. The shot-to-shot stability of plasma parameters facilitates the use of plasma guns in laboratory experiments. These types of plasma sources can be used in many applications like plasma opening switches, plasma devices, and as plasma sources.

Final results of the first phase of the PROTO-SPHERA experiment: obtainment of the full current stable screw pinch and first evidences of the jet + torus combined plasma configuration

In astrophysics, the boundary conditions for plasma phenomena are provided by nature and the astronomer faces the problem of understanding them from a variety of observations [Hester J J et al 1996 Astrophys. J. 456 225], on the other hand, in laboratory plasma experiments the electromagnetic boundary conditions become a major problem in the set-up of the machine that produces the plasma, an issue that has to be investigated step by step and to be modified and adapted with great patience, in particular in the case of an innovative plasma confinement experiment. The PROTO-SPHERA machine [Alladio F et al 2006 Nucl. Fusion 46 S613] is a magnetic confinement experiment, that emulates in the laboratory the jet + torus plasma configurations often observed in astrophysics: an inner magnetized jet of plasma centered on the(approximate) axis of symmetry and surrounded by a magnetized plasma torus orthogonal to this jet. The PROTO-SPHERA plasma is simply connected, i.e., no metal current conducting rod is linked to the plasma torus, while instead it is the inner magnetized plasma jet(in the following always called the plasma centerpost) that is linked to the torus. It is mandatory that no spurious plasma current path modifies the optimal shape of the plasma centerpost. Moreover, as the plasma torus is produced and sustained, in absence of any applied inductive electric field, by the inner plasma centerpost through magnetic reconnections [Taylor J B and Turner M F 1989 Nucl.Fusion 29 219], it is required as well that spurious current paths do not surround the torus on its outboard, in order not to lower the efficiency of the magnetic reconnections that maintain the plasma torus at the expense of the plasma centerpost. Boundary conditions have been corrected,up to the point that the first sustainment in steady state has been achieved for the combined plasma.

The multi-peak point phenomenon of broadband microwave reflection caused by inhomogeneous plasma

During spacecraft re-entry,the challenge of measuring plasma sheath parameters directly contributes to difficulties in addressing communication blackout.In this work,we have discovered a phenomenon of multiple peaks in reflection data caused by the inhomogeneous plasma.Simulation results show that the multi-peak points fade away as the characteristic frequency is approached,resembling a series of gradually decreasing peaks.The positions and quantities of these points are positively correlated with electron density,yet they show no relation to collision frequency.This phenomenon is of significant reference value for future studies on the spatial distribution of plasmas,particularly for using microwave reflection signals in diagnosing the plasma sheath.

Experimental confirmation of the linear relation between plasma current and external vertical magnetic field in EXL-50 spherical torus energetic electron plasmas

A three-fluid equilibrium plasma with bulk plasma and energetic electrons has been observed on the Xuanlong-50(EXL-50) spherical torus, where the energetic electrons play a crucial role in sustaining the plasma current and pressure. In this study, the equilibrium of a multi-fluid plasma was investigated by analyzing the relationship between the external vertical magnetic field(B_(V)),plasma current(I_(p)), the poloidal ratio(β_(p)) and the Shafranov formula. Remarkably, our research demonstrates some validity of the Shafranov formula in the presence of multi-fluid plasma in EXL-50 spherical torus. This finding holds significant importance for future reactors as it allows for differentiation between alpha particles and background plasma. The study of multi-fluid plasma provides a significant reference value for the equilibrium reconstruction of burning plasma involving alpha particles.

Effect of matrix thermal properties on laser-induced plasma

The matrix thermal properties have an important impact on laser-induced plasma,as the thermal effect dominates the interaction between ns-pulsed laser and matter,especially in metals.We used a series of pure metals and aluminum alloys to measure plasma temperature and electron density through laser-induced breakdown spectroscopy,in order to investigate the effect of matrix thermal properties on laser-induced plasma.In pure metals,a significant negative linear correlation was observed between the matrix thermal storage coefficient and plasma temperature,while a weak correlation was observed with electron density.The results indicate that metals with low thermal conductivity or specific heat capacity require less laser energy for thermal diffusion or melting and evaporation,resulting in higher ablation rates and higher plasma temperatures.However,considering ionization energy,thermal effects may be a secondary factor affecting electron density.The experiment of aluminum alloy further confirms the influence of thermal conductivity on plasma temperature and its mechanism explanation.

Tunable energy spectrum betatron x-ray sources in a plasma wakefield

X-ray sources with tunable energy spectra have a wide range of applications in different scenarios due to their different penetration depths.However,existing x-ray sources face difficulties in terms of energy regulation.In this paper,we present a scheme for tuning the energy spectrum of a betatron x-ray generated from a relativistic electron bunch oscillating in a plasma wakefield.The center energy of the x-ray source can be tuned from several keV to several hundred keV by changing the plasma density,thereby extending the control range by an order of magnitude.At different central energies,the brightness of the betatron radiation is in the range of 3.7×10^(22)to 5.5×10^(22)photons/(0.1%BW·s·mm^(2)·mrad^(2))and the photon divergence angle is about 2 mrad.This high-brightness,energy-controlled betatron source could pave the way to a wide range of applications requiring photons of specific energy,such as phase-contrast imaging in medicine,non-destructive testing and material analysis in industry,and imaging in nuclear physics.

Customized modulation on plasma uniformity by non-uniform magnetic field in capacitively coupled plasma

A two-dimensional fluid model based on COMSOL Multiphysics is developed to investigate the modulation of static magnetic field on plasma homogeneity in a capacitively coupled plasma(CCP)chamber. To generate a static magnetic field, direct current is applied to a circular coil located at the top of the chamber. By adjusting the magnetic field's configuration, which is done by altering the coil current and position, both the plasma uniformity and density can be significantly modulated. In the absence of the magnetic field, the plasma density exhibits an inhomogeneous distribution characterized by higher values at the plasma edge and lower values at the center. The introduction of a magnetic field generated by coils results in a significant increase in electron density near the coils. Furthermore, an increase in the sets of coils improves the uniformity of the plasma. By flexibly adjusting the positions of the coils and the applied current,a substantial enhancement in overall uniformity can be achieved. These findings demonstrate the feasibility of using this method for achieving uniform plasma densities in industrial applications.

Edge effect during microwave plasma chemical vapor deposition diamond-film:Multiphysics simulation and experimental verification

This study focused on the investigation of the edge effect of diamond films deposited by microwave plasma chemical vapor de-position.Substrate bulge height△h is a factor that affects the edge effect,and it was used to simulate plasma and guide the diamond-film deposition experiments.Finite-element software COMSOL Multiphysics was used to construct a multiphysics(electromagnetic,plasma,and fluid heat transfer fields)coupling model based on electron collision reaction.Raman spectroscopy and scanning electron microscopy were performed to characterize the experimental growth and validate the model.The simulation results reflected the experimental trends observed.Plasma discharge at the edge of the substrate accelerated due to the increase in△h(△h=0-3 mm),and the values of electron density(n_(c)),molar concentration of H(C_(H)),and molar concentration of CH_(3)(C_(CH_(3)))doubled at the edge(for the special concave sample with△h=−1 mm,the active chemical groups exhibited a decreased molar concentration at the edge of the substrate).At=0-3 mm,a high diamond growth rate and a large diamond grain size were observed at the edge of the substrate,and their values increased with.The uniformity of film thickness decreased with.The Raman spectra of all samples revealed the first-order characteristic peak of dia-mond near 1332 cm^(−1).When△h=−1 mm,tensile stress occurred in all regions of the film.When△h=1-3 mm,all areas in the film ex-hibited compressive stress.

A research on the effect of plasma spectrum collection device on LIBS spectral intensity

Only a small amount of spectral information is collected because the collection solid angle of the optical fiber probe and lens is very limited when collecting spectral information.To overcome this limitation,this study presents a novel method for acquiring plasma spectral information from various spatial directions.A parabolic-shaped plasma spectral collection device(PSCD)is employed to effectively collect more spectral information into the spectrometer,thereby enhancing the overall spectral intensity.The research objects in this study were soil samples containing different concentrations of heavy metals Pb,Cr,and Cd.The results indicate that the PSCD significantly enhances the spectral signal,with an enhancement rate of up to 45%.Moreover,the signal-to-noise ratio also increases by as much as 36%.Simultaneously,when compared to the absence of a device,it is found that there is no significant variation in plasma temperature when the PSCD is utilized.This observation eliminates the impact of the spatial effect caused by the PSCD on the spectral intensity.Consequently,a concentrationspectral intensity relationship curve is established under the PSCD.The results revealed that the linear fitting R^(2)for Pb,Cr,and Cd increased by 0.011,0.001,and 0.054,respectively.Additionally,the limit of detection(LOD)decreased by 0.361 ppm,0.901 ppm,and 0.602 ppm,respectively.These findings indicate that the spectral enhancement rate elevates with the increase in heavy metal concentration.Hence,the PSCD can effectively enhance the spectral intensity and reduce the detection limit of heavy metals in soil.

Impact of D-dimer on in-hospital mortality following aortic dissection:A systematic review and meta-analysis

BACKGROUND The utility of D-dimer(DD)as a biomarker for acute aortic dissection(AD)is recognized.Yet,its predictive value for in-hospital mortality remains uncertain and subject to conflicting evidence.AIM To conduct a meta-analysis of AD-related in-hospital mortality(ADIM)with elevated DD levels.METHODS We searched PubMed,Scopus,Embase,and Google Scholar for AD and ADIM literature through May 2022.Heterogeneity was assessed using I2 statistics and effect size(hazard or odds ratio)analysis with random-effects models.Sample size,study type,and patients’mean age were used for subgroup analysis.The significance threshold was P<0.05.RESULTS Thirteen studies(3628 patients)were included in our study.The pooled prevalence of ADIM was 20%(95%CI:15%-25%).Despite comparable demographic characteristics and comorbidities,elevated DD values were associated with higher ADIM risk(unadjusted effect size:1.94,95%CI:1.34-2.8;adjusted effect size:1.12,95%CI:1.05-1.19,P<0.01).Studies involving patients with a mean age of<60 years exhibited an increased mortality risk(effect size:1.43,95%CI:1.23-1.67,P<0.01),whereas no significant difference was observed in studies with a mean age>60 years.Prospective and larger sample size studies(n>250)demonstrated a heightened likelihood of ADIM associated with elevated DD levels(effect size:2.57,95%CI:1.30-5.08,P<0.01 vs effect size:1.05,95%CI:1.00-1.11,P=0.05,respectively).CONCLUSION Our meta-analysis shows elevated DD increases in-hospital mortality risk in AD patients,highlighting the need for larger,prospective studies to improve risk prediction models.

Wave field structure and power coupling features of blue-core helicon plasma driven by various antenna geometries and frequencies

This paper deals with wave propagation and power coupling in blue-core helicon plasma driven by various antennas and frequencies.It is found that compared to non-blue-core mode,for blue-core mode,the wave can propagate in the core region,and it decays sharply outside the core.The power absorption is lower and steeper in radius for blue-core mode.Regarding the effects of antenna geometry for blue-core mode,it shows that half helix antenna yields the strongest wave field and power absorption,while loop antenna yields the lowest.Moreover,near axis,for antennas with m=+1,the wave field increases with axial distance.In the core region,the wave number approaches to a saturation value at much lower frequency for non-blue-core mode compared to blue-core mode.The total loading resistance is much lower for blue-core mode.These findings are valuable to understanding the physics of blue-core helicon discharge and optimizing the experimental performance of blue-core helicon plasma sources for applications such as space propulsion and material treatment.

Effect of coil and chamber structure on plasma radial uniformity in radio frequency inductively coupled plasma

Enhancing plasma uniformity can be achieved by modifying coil and chamber structures in radio frequency inductively coupled plasma(ICP)to meet the demand for large-area and uniformly distributed plasma in industrial manufacturing.This study utilized a two-dimensional self-consistent fluid model to investigate how different coil configurations and chamber aspect ratios affect the radial uniformity of plasma in radio frequency ICP.The findings indicate that optimizing the radial spacing of the coil enhances plasma uniformity but with a reduction in electron density.Furthermore,optimizing the coil within the ICP reactor,using the interior point method in the Interior Point Optimizer significantly enhances plasma uniformity,elevating it from 56%to 96%within the range of the model sizes.Additionally,when the chamber aspect ratio k changes from 2.8 to 4.7,the plasma distribution changes from a center-high to a saddleshaped distribution.Moreover,the plasma uniformity becomes worse.Finally,adjusting process parameters,such as increasing source power and gas pressure,can enhance plasma uniformity.These findings contribute to optimizing the etching process by improving plasma radial uniformity.

Plasma density enhancement in radio-frequency hollow electrode discharge

The plasma density enhancement outside hollow electrodes in capacitively coupled radio-frequency(RF) discharges is investigated by a two-dimensional(2D) particle-in-cell/Monte-Carlo collision(PIC/MCC) model. Results show that plasma exists inside the cavity when the sheath inside the hollow electrode hole is fully collapsed, which is an essential condition for the plasma density enhancement outside hollow electrodes. In addition, the existence of the electron density peak at the orifice is generated via the hollow cathode effect(HCE), which plays an important role in the density enhancement. It is also found that the radial width of bulk plasma at the orifice affects the magnitude of the density enhancement, and narrow radial plasma bulk width at the orifice is not beneficial to obtain high-density plasma outside hollow electrodes.Higher electron density at the orifice, combined with larger radial plasma bulk width at the orifice,causes higher electron density outside hollow electrodes. The results also imply that the HCE strength inside the cavity cannot be determined by the magnitude of the electron density outside hollow electrodes.