A capillary-induced negative pressure is able to initiate heterogeneous cavitation.

A capillarity-induced negative pressure is of general importance for understanding the phase behaviors of liquids in small pores and cracks. A unique example is the embolism in the xylem of plants and the cavitation at the limiting negative pressure generated by evaporation of water from nanocapillaries in the cell walls of leaves. In this work, by combining the effect of a capillary and cavitation together, we demonstrate with molecular dynamics (MD) simulations that capillarity is able to induce spontaneous cavitation in the presence of hydrophobic heterogeneities. Our simulation results reveal separately how the capillary generates a negative pressure and how the generated negative pressure affects the onset of cavitation. We then interpret the cavitation mechanism and determine the occurrence of cavitation as a function of the hydrophobicity of the nucleating substrates where the cavitation initiates and as a function of the hydrophilicity of the capillary tube from which the negative pressure generates. Our results reveal that the capillary-induced cavitation can be described well with a heterogeneous nucleation mechanism, within the framework of classical nucleation theory.

Maximizing friction by liquid flow clogging in confinement.

In the nanoscale regime, flow behaviors for liquids show qualitative deviations from bulk expectations. In this work, we reveal by molecular dynamics simulations that plug flow down to nanoscale induces molecular friction that leads to a new flow structure due to the molecular clogging of the encaged liquid. This plug-like nanoscale liquid flow shows several features differ from the macroscopic plug flow and Poiseuille flow: It leads to enhanced liquid/solid friction, producing a friction of several order of magnitude larger than that of Couette flow; the friction enhancement is sensitively dependent of the liquid column length and the wettability of the solid substrates; it leads to the local compaction of liquid molecules that may induce solidification phenomenon for a long liquid column.

The fate of bulk nanobubbles under gas dissolution.

Artificially added or undesired organic and inorganic contaminants in solution that are interfacially active always tend to be adsorbed at the gas-liquid interface of micro- and nano-bubbles, affecting the stability of the tiny bubbles. In this work, by using molecular dynamics simulations we study how the adsorbed surfactant-like molecules, with their amphiphilic character, affect the dissolution of the existing bulk nanobubbles under low gas supersaturation environments. We find that, depending on the concentration of the dissolved gas and the molecular structure of surfactants, two fates of bulk nanobubbles whose interfaces are saturated by surfactants are found: either remaining stable or being completely dissolved. With gas dissolution, the bubble shrinks and the insoluble surfactants form a monolayer with an increasing areal density until an extremely low (close to 0) surface tension is reached. In the limit of vanishing surface tension, the chemical structure of surfactants crucially affects the bubble stability by changing the monolayer elastic energy. Two basic conditions for stable nanobubbles at low gas saturation are identified: vanishing surface tension due to bubble dissolution and positive spontaneous curvature of the surfactant monolayer. Based on this observation, we discuss the similarity in the stability mechanism of bulk nanobubbles and that of microemulsions.

Dynamic Equilibrium Model for Surface Nanobubbles in Electrochemistry.

Gas bubbles are ubiquitous in electrochemical processes, particularly in water electrolysis. Due to the development of gas-evolving electrocatalysis and energy conversion technology, a deep understanding of gas bubble behaviors at the electrode surface is highly desirable. In this work, by combining theoretical analysis and molecular simulations, we study the behaviors of a single nanobubble electrogenerated at a nanoelectrode. With the dynamic equilibrium model, the stability criteria for stationary surface nanobubbles are established. We show theoretically that a slight change in either the gas solubility or solute concentration results in various nanobubble dynamic states at a nanoelectrode: contact line pinning in aqueous and ethylene glycol solutions, oscillation of pinning states in dimethyl sulfoxide, and mobile nanobubbles in methanol. The above complex nanobubble behavior at the electrode/electrolyte interface is explained by the competition between gas influx into the nanobubble and outflux from the nanobubble.

Surface enrichment of ions leads to the stability of bulk nanobubbles.

Numerous experiments have shown that bulk nanobubble suspensions are often characterized by a high magnitude of zeta potential. However, the underlying physical mechanism of how the bulk nanobubbles can stably exist has remained unclear so far. In this paper, based on theoretical analysis, we report a stability mechanism for charged bulk nanobubbles. The strong affinity of negative charges for the nanobubble interface causes charge enrichment, and the resulting electric field energy gives rise to a local minimum for the free energy cost of bubble formation, leading to thermodynamic metastability of the charged nanobubbles. The excess surface charges mechanically generate a size-dependent force, which balances the Laplace pressure and acts as a restoring force when a nanobubble is thermodynamically perturbed away from its equilibrium state. With this negative feedback mechanism, we discuss the nanobubble stability as a function of surface charge and gas supersaturation. We also compare our theoretical prediction with recent experimental observations, and a good agreement is found. This mechanism provides new fundamental insights into the origin of the unexplained stability of bulk nanobubbles.

Stability of Surface Nanobubbles without Contact Line Pinning.

Although the stability of most surface nanobubbles observed can be well interpreted by contact line pinning and supersaturation theory, there is increasing evidence that at least for certain situations, contact line pinning is not required for nanobubble stability. This raises a significant question of what is the stability mechanism for those sessile nanobubbles. Through theoretical analysis and molecular dynamics simulations, in this work, we report two mechanisms for stabilizing surface nanobubbles on flat and homogeneous substrates. One is attributed to constant adsorption of trace impurities on the nanobubble gas?liquid interface, through which nanobubble growing or shrinking causes the increase and decrease of interfacial tension, acting as a restoring force to bring the nanobubble to its equilibrium size. The other is attributed to the deformation of a soft substrate induced by the formed nanobubble, which in turn stabilizes the nanobubble via impeding the contact line motion, similar to self-pinning of microdroplets on soft substrates. Both mechanisms can interpret, depending on the specified conditions, how surface nanobubbles can remain stable in the absence of contact line pinning.

Surface Nanobubbles Nucleate Liquid Boiling.

Surface nanobubbles have been presumed to lead to the experimental observation that liquid boiling often occurs at a much lower supersaturation than expected, yet no qualitative theory exists to explain how they participate in the process. Here, we report through a simple theoretical analysis on how the metastable nanobubbles nucleate the liquid-to-vapor transition by serving as an intermediate phase. The appearance of metastable nanobubbles inhibits the shrink of the bubble nucleus and changes bubble nucleation into a multistep process. We show three possible mechanisms for heterogeneous nucleation starting from metastable surface nanobubbles: nucleation from pinned nanobubbles, nucleation via nanobubble depinning, and nucleation through nanobubble coalescence, each predicting a significant reduction in a nucleation barrier. The occurrence of a specific nucleation pathway of bubble nucleation depends on the detailed geometry of local substrate roughness. These results give insight into how the appearance of surface nanobubbles changes the nucleation mechanisms of liquid boiling.

Solvent Exchange Leading to Nanobubble Nucleation: A Molecular Dynamics Study.

The solvent exchange procedure has become the most-used protocol to produce surface nanobubbles, while the molecular mechanisms behind the solvent exchange are far from being fully understood. In this paper, we build a simple model and use molecular dynamics simulations to investigate the dynamic characteristics of solvent exchange for producing nanobubbles. We find that at the first stage of solvent exchange, there exists an interface between interchanging solvents of different gas solubility. This interface moves toward the substrate gradually as the exchange process proceeds. Our simulations reveal directed diffusion of gas molecules against the gas concentration gradient, driven by the solubility gradient of the liquid composition across the moving solvent-solvent interface. It is this directed diffusion that causes gas retention and produces a local gas oversaturation much higher near the substrate than far from it. At the second stage of solvent exchange, the high local gas oversaturation leads to bubble nucleation either on the solid surface or in the bulk solution, which is found to depend on the substrate hydrophobicity and the degree of local gas oversaturation. Our findings suggest that solvent exchange could be developed into a standard procedure to produce oversaturation and used to a variety of nucleation applications other than generating nanobubbles.

What experiments on pinned nanobubbles can tell about the critical nucleus for bubble nucleation.

The process of homogeneous bubble nucleation is almost impossible to probe experimentally, except near the critical point or for liquids under large negative tension. Elsewhere in the phase diagram, the bubble nucleation barrier is so high as to be effectively insurmountable. Consequently, there is a severe lack of experimental studies of homogenous bubble nucleation under conditions of practical importance (e.g., cavitation). Here we use a simple geometric relation to show that we can obtain information about the homogeneous nucleation process from Molecular Dynamics studies of bubble formation in solvophobic nanopores on a solid surface. The free energy of pinned nanobubbles has two extrema as a function of volume: one state corresponds to a free-energy maximum ("the critical nucleus"), the other corresponds to a free-energy minimum (the metastable, pinned nanobubble). Provided that the surface tension does not depend on nanobubble curvature, the radius of the curvature of the metastable surface nanobubble is independent of the radius of the pore and is equal to the radius of the critical nucleus in homogenous bubble nucleation. This observation opens the way to probe the parameters that determine homogeneous bubble nucleation under experimentally accessible conditions, e.g. with AFM studies of metastable nanobubbles. Our theoretical analysis also indicates that a surface with pores of different sizes can be used to determine the curvature corrections to the surface tension. Our conclusions are not limited to bubble nucleation but suggest that a similar approach could be used to probe the structure of critical nuclei in crystal nucleation.

Hidden Nanobubbles in Undersaturated Liquids.

Here, we propose theoretically the existence of a new type of nanobubble in undersaturated liquids. These nanobubbles have a concave vapor-liquid interface featured with a negative curvature rather than a positive curvature for nanobubbles in supersaturated liquids, so that they often hide inside of the substrate textures and it might not be easy to characterize them through atomic force microscopy (AFM) measurements. However, these hidden nanobubbles are still stabilized by the contact line pinning effect and stay at the thermodynamically metastable state. We further demonstrate that similar to the nanobubbles in supersaturated liquids the contact angle of the hidden nanobubbles is more sensitive to the nanobubble size rather than the substrate chemistry, and their curvature radius is dependent on the chemical potential but independent of the base radius. Finally, we show several potential situations for the appearance of the hidden nanobubbles.

Modeling the Interaction between AFM Tips and Pinned Surface Nanobubbles.

Although the morphology of surface nanobubbles has been studied widely with different AFM modes, AFM images may not reflect the real shapes of the nanobubbles due to AFM tip-nanobubble interactions. In addition, the interplay between surface nanobubble deformation and induced capillary force has not been well understood in this context. In our work we used constraint lattice density functional theory to investigate the interaction between AFM tips and pinned surface nanobubbles systematically, especially concentrating on the effects of tip hydrophilicity and shape. For a hydrophilic tip contacting a nanobubble, its hydrophilic nature facilitates its departure from the bubble surface, displaying a weak and intermediate-range attraction. However, when the tip squeezes the nanobubble during the approach process, the nanobubble shows an elastic effect that prevents the tip from penetrating the bubble, leading to a strong nanobubble deformation and repulsive interactions. On the contrary, a hydrophobic tip can easily pierce the vapor-liquid interface of the nanobubble during the approach process, leading to the disappearance of the repulsive force. In the retraction process, however, the adhesion between the tip and the nanobubble leads to a much stronger lengthening effect on nanobubble deformation and a strong long-range attractive force. The trends of force evolution from our simulations agree qualitatively well with recent experimental AFM observations. This favorable agreement demonstrates that our model catches the main intergradient of tip-nanobubble interactions for pinned surface nanobubbles and may therefore provide important insight into how to design minimally invasive AFM experiments.

Stability of micro-Cassie states on rough substrates.

We numerically study different forms of nanoscale gaseous domains on a model for rough surfaces. Our calculations based on the constrained lattice density functional theory show that the inter-connectivity of pores surrounded by neighboring nanoposts, which model the surface roughness, leads to the formation of stable microscopic Cassie states. We investigate the dependence of the stability of the micro-Cassie states on substrate roughness, fluid-solid interaction, and chemical potential and then address the differences between the origin of the micro-Cassie states and that of surface nanobubbles within similar models. Finally, we show that the micro-Cassie states share some features with experimentally observed micropancakes at solid-water interfaces.

N6-methyladenosine modified circPAK2 promotes lymph node metastasis via targeting IGF2BPs/VEGFA signaling in gastric cancer.

Circular RNAs (circRNAs) have emerged as key regulators of cancer occurrence and progression, as well as promising biomarkers for cancer diagnosis and prognosis. However, the potential mechanisms of circRNAs implicated in lymph node (LN) metastasis of gastric cancer remain unclear. Herein, we identify a novel N6-methyladenosine (m6A) modified circRNA, circPAK2, which is significantly upregulated in gastric cancer tissues and metastatic LN tissues. Functionally, circPAK2 enhances the migration, invasion, lymphangiogenesis, angiogenesis, epithelial-mesenchymal transition (EMT), and metastasis of gastric cancer in vitro and in vivo. Mechanistically, circPAK2 is exported by YTH domain-containing protein 1 (YTHDC1) from the nucleus to the cytoplasm in an m6A methylation-dependent manner. Moreover, increased cytoplasmic circPAK2 interacts with Insulin-Like Growth Factor 2 mRNA-Binding Proteins (IGF2BPs) and forms a circPAK2/IGF2BPs/VEGFA complex to stabilize VEGFA mRNA, which contributes to gastric cancer vasculature formation and aggressiveness. Clinically, high circPAK2 expression is positively associated with LN metastasis and poor prognosis in gastric cancer. This study highlights m6A-modified circPAK2 as a key regulator of LN metastasis of gastric cancer, thus supporting circPAK2 as a promising therapeutic target and prognostic biomarker for gastric cancer.

Recurrent metastatic patterns and prognosis after radical surgery in patients with alpha-fetoprotein-producing gastric cancer: a retrospective cohort study.

Alpha-fetoprotein-producing gastric cancer (AFPGC) is a rare and aggressive subtype of gastric cancer associated with poor prognosis. This study aimed to investigate the recurrent metastatic patterns and prognostic factors in AFPGC patients undergoing radical surgical resection. Data from 241 AFPGC patients diagnosed between January 2017 and January 2020 who underwent surgical resection were analyzed across multiple centers. Recurrence patterns, metastatic sites, and survival outcomes were evaluated. Univariate and multivariate analyses were performed to identify risk factors for recurrent metastasis, overall survival (OS), and disease-free survival (DFS). There is an annual increase in the proportion of AFPGC cases, rising from 3.45% in 2017 to 7.88% in 2023. Higher serum AFP level was associated with increased likelihood of lymph node metastasis (P=0.006), deeper invasion depth (P=0.000) and greater tumor diameter (P=0.036). Independent predictors of recurrent metastasis included T4 infiltration, lymph node metastasis, tumor diameter >5 cm, poorly differentiated-undifferentiated pathology, preoperative AFP>1000 ng/mL, and postoperative increasing trend in AFP levels. The 5-year OS and DFS rates were 36.5% and 34.2%, respectively, with poorer survival linked to higher preoperative AFP levels and postoperative increasing trend in AFP level. Independent risk factors for poor OS and DFS included T4 infiltration, lymph node metastasis, poorly differentiated-undifferentiated pathology, preoperative AFP>1000 ng/mL, and postoperative increasing trend in AFP. Serum AFP level can serve as a potential predictive and prognostic biomarker. Identifying independent risk factors informs risk stratification and personalized treatment for AFPGC patients.

Prognostic nomogram for Siewert type II adenocarcinoma of the esophagogastric junction patients with and without neoadjuvant radiotherapy: a retrospective cohort study.

OBJECTIVE: To compare the prognostic factors of Siewert type II AEG patients who had received neoadjuvant radiotherapy (nRT) versus those who did not receive nRT. Nomograms for outcome prediction were constructed for the two treatment modalities. MATERIALS AND METHODS: Data for 1,745 Siewert II type AEG patients who underwent radical surgery between 2010 and 2015 were retrieved from SEER (Surveillance, Epidemiology, and End Results) database. Patients were assigned to neoadjuvant radiotherapy (nRT) and non-neoadjuvant radiotherapy (non-nRT) groups based on treatment modality. Independent prognostic predictors were used to develop nomograms. Concordance index (C-index), receiver operating characteristic (ROC), calibration curves, and decision curve analyses (DCA) were used to determine the performance and prognostic value of the nomograms. The predictive accuracy of nomograms was compared with the prognostic value of the Tumor-Node-Metastasis (TNM) staging system. RESULTS: The results showed that age, lymph node rate (LNR), and the number of removed lymph nodes (RLN) were independent prognostic factors for CSS in the nRT group. Tumor size, tumor grade, T stage, LNR, and therapy type were independent prognosis factors for CSS in patients in the non-nRT group. The C-indices for the nomograms were 0.652 (95% CI, 0.614-0.690) and 0.663 (95% CI, 0.606-0.720) in the training and validation cohort, respectively, for the nRT group. C-indices for the nomogram in non-nRT group were 0.754 (95% CI, 0.723-0.785) and 0.747 (95% CI, 0.688-0.800) for the training and validation cohorts, respectively. C-indices and ROC curves showed good predictive value compared with the TNM staging system in both groups. C-indices, as well as the AUC values of the nomograms and the TNM staging system for both cohorts in the non-nRT group were higher compared with those in the nRT group. Analysis of the survival calibration curve revealed high consistency between actual versus predicted outcomes determined by the nomograms. Decision curve analyses revealed that the new models had higher prediction value and clinical significance compared with TNM staging system. CONCLUSION: The established nomograms showed high prognostic value for Siewert type II AEG patients in both nRT and non-nRT groups. In addition, the nomogram and the TNM staging systems showed better prognostic performance for patients in the non-nRT group compared with patients in the nRT group.

Nomograms for Predicting Disease-Free Survival in Patients With Siewert Type II/III Adenocarcinoma of the Esophagogastric Junction Receiving Neoadjuvant Therapy and Radical Surgery.

Objective: This study aimed to develop prognostic prediction models for patients with Siewert type II/III adenocarcinoma of the esophagogastric junction (AEG) who received neoadjuvant therapy (neoadjuvant chemoradiotherapy or neoadjuvant chemotherapy) and radical surgery. A baseline nomogram and a post-operative nomogram were constructed before neoadjuvant therapy and after surgery. The predictive performance of the constructed nomograms was internally validated and compared to the TNM staging system. Materials and Methods: A total of 245 patients diagnosed with Siewert type II/III AEG and treated with neoadjuvant therapy followed by radical surgery at The Fourth Hospital of Hebei Medical University between January 2011 and December 2017 were enrolled. The variables before neoadjuvant therapy were defined as baseline factors, while the variables of baseline factors along with the variables of treatment and postoperative pathology were defined as post-operative factors. To construct the corresponding nomograms, independent predictors of baseline and post-operative factors were identified. The C-index and a time-dependent receiver operating characteristic curve were used to evaluate the model's discrimination ability. The calibration ability of the model was determined by comparing the probability of predicted free-recurrence to the actual free-recurrence. Decision curve analysis (DCA) was used to determine the clinical usefulness of the nomogram. Results: Among the baseline factors, age, cT stage, cN stage, Borrmann type, and staging laparoscopy were independent prognostic predictors. In contrast, among the post-operative factors, age, cN stage, staging laparoscopy, ypT stage, clinical response, number of positive lymph nodes, number of negative lymph nodes, laurén classification, and lymphatic, or perineural invasion (VELPI) were independent prognostic predictors. The two nomograms were constructed using the independent predictors of prognosis. The C-indexes for the baseline and post-operative nomograms were 0.690 (95% CI, 0.644-0.736) and 0.817 (95% CI, 0.782-0.853), respectively. The AUCs of the baseline nomogram at 3 and 5 years were both greater than cTNM (73.1 vs 58.8, 76.1 vs 55.7). Similarly, the AUCs of the post-operative nomogram were both greater than ypTNM (85.2 vs 69.1, 88.2 vs 71.3) at 3 and 5 years. The calibration curves indicated that both models had a high degree of calibration ability. By comparing the DCA at 3 and 5 years, we determined that the two nomograms constructed had better clinical utility than the TNM staging system. Conclusions: The constructed nomograms have a more accurate predictive ability than the eighth edition TNM staging system, which can be useful for treatment selection and follow-up monitoring of patients.

A Nomogram for Predicting the Risk of Pulmonary Hypertension for Patients with Chronic Obstructive Pulmonary Disease.

Background: Pulmonary hypertension (PH) is a life-threatening complication of chronic obstructive pulmonary disease (COPD). Timely diagnosis of PH in COPD patients is vital to achieve proper treatment; however, there is no algorithm to identify those at high risk. We aimed to develop a predictive model for PH in patients with COPD that provides individualized risk estimates. Methods: A total of 527 patients with COPD who were admitted to our hospital between May 2019 and December 2020 were retrospectively enrolled in this study. Using echocardiographic results as a standard, patients were stratified into a moderate- or high-PH probability group and a low-PH probability group. They were randomly grouped into either the training set (n = 368 patients) or validation set (n = 159 patients) in a ratio of 7:3. We utilized the least absolute shrinkage and selection operator (LASSO) regression model to select the feature variables. The characteristic variables selected in the LASSO regression were analyzed using multivariable logistic regression to construct the predictive model. The predictive model was displayed using a nomogram. We used the receiver operating characteristic curve, calibration curve, and clinical decision curve analysis (DCA) to evaluate model performance, and internal validation was assessed. Results: The predictive factors included in the prediction model were Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage, emphysema, PaCO2, NT-pro-BNP, red blood cell (RBC) distribution width-standard deviation (RDW-SD), and neutrophil/lymphocyte ratio (NLR). The predictive model yielded an area under the curve (AUC) of 0.770 (95% confidence interval [CI], 0.719-0.820); in the internal validation, the AUC was 0.741 (95% CI, 0.659-0.823). The predictive model was well calibrated, and the DCA showed that the proposed nomogram had strong clinical applicability. Conclusion: This study showed that a simple nomogram could be used to calculate the risk of PH in patients with COPD which can be useful for the individualized clinical management of COPD patients who may be occur with PH. Further studies need to be confirmed by larger sample sizes and validated in the stable COPD population.

Oscillating state transition in pinned nanobubbles with coupled fluctuations.

Analogous to other porous solids, pinned nanobubbles serve as a zero-dimensional stable nanoscale chamber with controllable thermodynamic parameters, whereas they can respond to state change of guest molecule. Here we analyzed peculiarities of phase transitions in pinned nanobubbles, which were experimentally proved to be superstable. By combining molecular dynamics simulation and thermodynamic analysis, we reveal that guest molecules encapsulated inside a nanobubble exhibit distinct state behaviors: a state in vapor phase, a reversible two-state oscillation, and a stable nanodroplet@nanobubble state, depending on the number of guest molecules and the external pressure. The free-energy landscape shows how state metastability gradually develops with external stimuli and leads to the specific bistable state of two-state oscillation. The existence of strong coupling between nanobubble breathing and two-state oscillation is identified. Our simulation results demonstrate that the flexibility of pinned nanobubbles plays at least the same important role as space confinement in determining the states of guest molecules. Our findings indicate that pinned nanobubbles, serving as soft porous media that possess high stability and reversible transformability, show a wealth of properties that are not found in bulk solutions and in porous solids.

[Risk factors analysis of central venous catheter-related thrombosis in critically ill patients and development of nomogram prediction model].

OBJECTIVE: To analyze the risk factors of central venous catheter-related thrombosis (CRT) in critically ill patients and develop the model of a nomogram. METHODS: A prospective investigation study was conducted on 385 critically ill patients who received central venous catheters during hospitalization in Hengshui People's Hospital from May 2018 to March 2021. Color Doppler ultrasonography was performed daily after catheterization. Patients were divided into thrombosis group and non-thrombosis group according to whether CRT was formed. The patient's gender, age, body mass index (BMI), acute physiology and chronic health evaluation II (APACHE II) score, complications, existing tumor, D-dimer level on the 3rd day after catheterization, maximum velocity of right internal jugular vein on the 3rd day after catheterization, mechanical ventilation time, and catheter indwelling time were recorded, and the differences of above indexes between the two groups were compared. Multivariate Logistic regression was performed on the influencing factors with statistical differences between the two groups to establish the nomogram prediction. The receiver operator characteristic curve (ROC curve) and calibration curve were used to evaluate the predictive power of the model. RESULTS: The incidence of central venous CRT in critically ill patients was 16.1% (62/385). Compared with non-thrombosis patients, the thrombosis group patients had higher APACHE II score, the proportion of existing tumor, and D-dimer level on the 3rd day after catheterization [APACHE II score: 17 (15, 19) vs. 15 (12, 18), the proportion of existing tumor: 51.6% (32/62) vs. 35.3% (114/323), D-dimer (mg/L): 0.84 (0.64, 0.94) vs. 0.57 (0.44, 0.76), all P < 0.05], the maximum flow rate of right internal jugular vein was slower on the 3rd day after catheterization [cm/s: 14 (13, 15) vs. 16 (14, 18), P < 0.05]. Univariate analysis showed that high APACHE II score, critical patients with existing tumor, high D-dimer level on the 3rd day after catheterization, and slow maximum flow rate of right internal jugular vein on the 3rd day after catheterization were more likely to develop central venous CRT. Further multivariate Logistic regression analysis showed that high APACHE II score, existing tumor, high D-dimer level on the 3rd day after catheterization and slow maximum flow rate of right internal jugular vein on the 3rd day after catheterization were independent risk factors for central venous CRT in critical patients [odds ratio (OR) and 95% confidence interval (95%CI) were 0.876 (0.801-0.957), 0.482 (0.259-0.895), 0.039 (0.011-0.139), 1.401 (1.218-1.611), and P values were 0.003, 0.021, < 0.001, < 0.001, respectively]. According to the results of multivariate analysis, the prediction model of the nomogram was constructed. The area under ROC curve (AUC) was 0.820, 95%CI was 0.767-0.872, P < 0.001. The calibration curve showed that the prediction probability of central venous CRT nomogram model in critically ill patients had good consistency with the actual occurrence probability. CONCLUSIONS: Existing tumor, high APACHE II score, elevated D-dimer on the 3rd day after catheterization, and decreased maximum velocity of right internal jugular vein on the 3rd day after catheterization are independent risk factors for central venous CRT in critical patients. The prediction model based on the proposed model has good clinical efficacy.

Enhanced fluctuation for pinned surface nanobubbles.

By employing molecular dynamics simulations we investigate the fluctuation of surface nanobubbles immersed in liquid phase. Our simulation results indicate that in comparison with the surrounding liquid and nanobubble interior, the vapor-liquid or gas-liquid interface of nanobubbles always exhibits the largest compressibility, demonstrating the enhanced fluctuation for nanobubble interfaces. We also find that vapor surface nanobubbles and gas surface nanobubbles exhibit different fluctuation behaviors. For vapor nanobubbles that appear in overheated pure liquid, both density fluctuation and interface fluctuation are independent on the external pressure since the internal pressure remains constant at a given temperature. For gas nanobubbles that appear in gas supersaturated solution, the density fluctuation monotonously decreases with the increase of gas concentration, while the interface fluctuation shows a nonmonotonic variation. Departure from the intermediate gas concentration with the minimal interface fluctuation would enhance the fluctuation, which may finally lead to nanobubble destabilization. Finally, our simulation results indicate that the complicated interface fluctuation of surface nanobubbles comprises two different modes: interface deformation and interface oscillation, both of which display similar trends as that of the combined interface fluctuation.