Mesoscopic ring element growth and deformation induced biofilm streamer evolution in microfluidic channels.

In a fluid environment, biofilms usually form and grow into streamers attached to solid surfaces. Existing research on single streamers studied their formation and failure modes. In the experiment on biofilm growth in a microfluidic channel, we found that rings composed of bacteria and an extracellular matrix are important elements on a mesoscopic scale. In the fluid environment, the failure of these ring elements causes damage to streamers. We simulated the growth and deformation of the ring structure in the micro-channel using multi-agent simulation and fluid-structure coupling of a porous elastic body. Based on this, we simulated the biofilm evolution involving multi-ring deformation, which provides a new length scale to study the biofilm streamer dynamics in fluid environments.

Retroperitoneal Castlemans disease mimicking a liver cancer: a case report.

Castleman disease (CD), a distinct lymphoproliferative disorder, is infrequently encountered in clinical practice and poses significant diagnostic challenges. We present the case of a 48-year-old asymptomatic female, admitted for evaluation of a hepatic mass detected in the liver's right lobe. Preoperative laboratory tests were within normal limits. Diagnostic imaging, including contrast-enhanced magnetic resonance imaging (MRI), was suggestive of hepatocellular carcinoma. Furthermore, contrast-enhanced abdominal computed tomography (CT) scans were indicative of hepatic malignancy. Subsequently, the patient underwent laparoscopic surgery targeting a retroperitoneal mass. During the surgical procedure, it was observed that the tumor was a retroperitoneal mass situated posterior to the liver, exhibiting localized adhesion to hepatic tissue. The postoperative histopathological analysis revealed the mass to be hyaline-vascular type Castleman disease (HV-CD), thereby refuting the initial diagnosis of a hepatic malignancy. This case underscores the complexity of diagnosing retroperitoneal Castleman disease, particularly when it masquerades as a hepatic tumor.

The porous structure induced heterogeneous and localized failure of the biofilm in microfluidic channels.

Understanding the mechanism of biofilm distribution and detachment is very important to effectively improve water treatment and prevent blockage in porous media. The existing research is more related to the local biofilm evolving around one or few microposts and the lack of the integral biofilm evolution in a micropost array for a longer growth period. This study combines microfluidic experiments and mathematical simulations to study the distribution and detachment of biofilm in porous media. Microfluidic chips with an array of microposts with different sizes are designed to simulate the physical pore structure of soil. The research shows that the initial formation and distribution of biofilm are influenced by bacterial transport velocity gradients within the pore space. Bacteria prefer to aggregate areas with smaller microposts, leading to the development of biofilm in those regions. Consequently, impermeable blockage structures form in this area. By analyzing experimental images of biofilm structures at the later stages, as well as coupling fluid flow and porous medium, and the finite element simulation, we find that the biofilm detachment is correlated with the morphology and permeability (kb) (from 10-15 to 10-9 m2) of the biofilm. The simulations show that there are two modes of biofilm detachment, such as internal detachment and external erosion.

Clinical characteristics and short-term outcomes of acute pancreatitis among patients with COVID-19.

OBJECTIVE: The existing literature on the combination of acute pancreatitis (AP) and COVID-19 is scarce. The objective of our study is to compare the clinical outcomes and occurrence of long COVID syndrome in AP patients with and without COVID-19, while investigating the potential impact of COVID-19 on the severity, mortality rate, and long COVID syndrome in these patients. METHODS: This retrospective, observational study was conducted at a single center. It included patients aged 18 years and above who were diagnosed with AP during the pandemic. Patients were categorized into two groups based on the results of RT-qPCR testing: the SARS-CoV-2-positive group and the SARS-CoV-2-negative group. The study aimed to compare the severity of AP, mortality rate, and occurrence of long COVID syndrome between these two groups. RESULT: A retrospective review was conducted on 122 patients diagnosed with acute pancreatitis between December 1, 2022, and January 31, 2023. Out of these patients, 100 were included in the study. The analysis revealed no significant differences in mortality rate, severity, and sequelae between AP patients with COVID-19 and those without COVID-19 (p > 0.005). However, a statistically significant difference was observed in the occurrence of long COVID syndrome, specifically in the presence of cough (p = 0.04). CONCLUSION: This study demonstrates that the presence of COVID-19 in patients with pancreatitis does not lead to an increase in the mortality and severity rate of pancreatitis.

Xanthogranulomatous inflammation involving the gallbladder, bile duct, and pancreas: a case report.

Xanthogranulomatous inflammation (XGI) is a rare, benign condition that can affect several organs, including the gallbladder, kidney, skin, gastrointestinal tract, lymph nodes, and soft tissues. It is often misdiagnosed as a malignancy. In this report, we present the case of a 79-year-old male who presented with persistent jaundice for 11 months. Computed tomography and magnetic resonance imaging revealed pancreatic head enlargement, gallbladder thickening, and common bile duct thickening, leading to a preoperative diagnosis of malignant neoplasm of the pancreatic head. During surgery, dense adhesions were found around the portal vein, suggestive of mass invasion. To relieve obstruction, choledochojejunostomy was performed. Postoperative pathological examination revealed xanthogranulomatous cholecystitis (XGCc), xanthogranulomatous cholangitis (XGCg), and xanthogranulomatous pancreatitis (XGP). XGI affecting the bile ducts and pancreas is extremely rare, and there are no reported cases of simultaneous involvement of the gallbladder, bile duct, and pancreas by XGI. This study provides valuable insight into the differential diagnosis of XGI by presenting the imaging features of XGI patients.

Comparative outcomes of single-incision laparoscopic, mini-laparoscopic, four-port laparoscopic, three-port laparoscopic, and single-incision robotic cholecystectomy: a systematic review and network meta-analysis.

Benign gallbladder diseases are common in surgery department, and the laparoscopic cholecystectomy (LC) is the gold standard procedure for benign diseases of gallbladder. Laparoscopic cholecystectomy is conventionally performed using four laparoscopic ports. However, the clinical application of different LCs is equivocal and there is no comprehensive comparison to explore which surgical options could benefit patients with benign gallbladder diseases. A network meta-analysis (NMA) to evaluate the efficacy of the different LCs could benefit patients with benign gallbladder diseases by comprehensive comparison. A systematic literature search was performed using PubMed, Embase, and Cochran Library. Totally, 17 randomized controlled trials (RCTs) (n = 1627) met study selection criteria and were incorporated in this NMA study. The first ranking probabilities of the five surgical options to alleviate postoperative pain scores were: 54.4% for single-incision robotic cholecystectomy (SIRC), 25.2% for single-incision laparoscopic cholecystectomy (SALC), and 24.9% for mini-laparoscopic cholecystectomy (Mini). The first ranking probabilities for reducing postoperative complications in the surgical options were: 61.3% for three-port laparoscopic cholecystectomy and 21.8% for four-port laparoscopic cholecystectomy. The first ranking probabilities for reducing hospital stay(days) in the surgical options were: 32.3% for SIRC, 29.0% for three-port laparoscopic cholecystectomy and 19.8% for four-port laparoscopic cholecystectomy. The first ranking probabilities for reducing operation time showed that the three-port technique had the shortest operation time, followed by three-port laparoscopic cholecystectomy (51.3%), four-port laparoscopic cholecystectomy (26.8%), and mini-laparoscopic cholecystectomy (21.6%). Our study found that the optimal surgical plan for different outcomes varies, making it difficult to give a comprehensive recommendation. Three-port laparoscopic cholecystectomy and four-port laparoscopic cholecystectomy may be the best options in terms of reducing surgical complications and operative time. Meanwhile, SIRC is the best options for relieving postoperative pain relief. SIRC and three-port laparoscopic cholecystectomy can reduce hospital stay (days) compared other LCs.

Matrix-producing cells formed 'Van Gogh bundles' facilitate Bacillus subtilis biofilm self-healing.

Biofilms grow and expand through cell differentiation into various phenotypes, which have different functions and cooperate with each other. In our experiments, we find that biofilms can heal after damaged, and we also find there is a special structure near the cut, which is called the 'Van Gogh bundles' by Jordi et al. because of its resemblance to Van Gogh's famous painting 'The Starry Night'. Here, we study the 'Van Gogh bundles' structure evolution near the cut area, and how 'Van Gogh bundles' structure facilitates the cut healing by observing microscopic images of bacterial colonies growing from wild-type and mutant strains. We find that the amount of matrix-producing cells contributes to the 'Van Gogh bundles' structure, such as curvature. Through the comparison of curvatures of 'Van Gogh bundles' and the rate of the cut healing, we find that the smaller the curvature, the faster healing rate. To better explain the above experiment observations, we establish an individual-based model and simulate the formation and growth of 'Van Gogh bundles' along the cut by giving rules for an individual cell like cell growth, division and turning rules, and also 'Van Gogh bundles' fold division rule.

Osmotic pressure induced by extracellular matrix drives Bacillus subtilis biofilms' self-healing.

The formation of bacterial biofilms is due to the bacteria adhering to the contact surface, secreting exopolysaccharide (EPS) and proteins, which make a large number of bacteria aggregate to form communities. In our experiments, we find that biofilms can heal after being destroyed like cut. To understand how biofilms self-heal, we use a diffusion-reaction continuum model to simulate the biofilm self-healing process, by using the extended finite element and level set method through MATLAB. The extended finite element method is used to calculate the diffusion of nutrients and the pressure field in the biofilm during the self-healing process, and the level set method is used to track the biofilm edge expansion and the cutting edge healing. The result can well describe the experimental observation, we find that the cut in the young biofilm heals almost completely, while old biofilms heal only at the edge. According to the phenotype observation, we find that matrix producing cells contribute to the biofilm self-healing, matrix producing cells secrete exopolysaccharide causing the difference of macromolecular substances' concentration in the biofilm and the agar substrate, which results in osmotic pressure promoting the transport of nutrients and leads to cut healing. Our simulation demonstrates that the nutrient concentration and the osmotic pressure are confinements for the biofilm healing.

Effect of microfluidic channel geometry on Bacillus subtilis biofilm formation.

Biofilms are microbial colonies encased in an extracellular polymer matrix self-secreted through bacterial proliferation and differentiation. Biofilms exist almost everywhere such as sewers, rivers and oceans. In the fluid environment, the formation of biofilms is closely related to the relevant parameters of the flow field, such as the shear stress, the secondary flow, and the Reynolds number. In this paper, we use microfluidic channels made of polydimethylsiloxane to study the channel-geometry effect on Bacillus subtilis biofilms formation, such as the biofilm adhesion and structure. Our study shows that both the shear stress and the secondary flow play roles in the biofilm adhesion at the initial stage, the shear stress decides whether the biofilm adheres, if yes, then the secondary flow determines the adhesion rate. Our study further shows that after the biofilm forms, its structure evolves from loose to dense, with a concomitant 20-times rise in adhesion. Our study provides new insights into the adhesion of biofilms in natural and industrial fluid environments and helps understand the growth of biofilms.

Biofilm streamer growth dynamics in various microfluidic channels.

Biofilms are microbial colonies that are encapsulated in extracellular polymers secreted by cells through their proliferation and differentiation. Biofilms exist on solid surfaces, liquid surfaces, or in liquid media, where the growth of the bacterial biofilm is closely related to the velocity of the secondary flow, main flow, and geometry of the channel, which are difficult to measure in a natural fluid environment, making the study of the biofilm streamer growth process difficult. In this study, we used microfluidic channels made of polydimethylsiloxane to study the growth dynamics of Bacillus subtilis biofilm streamers. We observed that the biofilm streamer growth undergoes three stages with different growth characteristics. First, we found that the initial growth of the streamer is located at the position with the maximum value of P = secondary flow velocity × main flow velocity. Second, the biofilm underwent floating growth around the microcolumn obstacle. After the transition stage, the last growth stage includes two types because of the different attachment strengths and mechanical properties of the biofilm. Our research provides new insights into the formation and shedding of biofilm streamers in natural and industrial environments and helps us to better understand biofilm growth in fluid flow.

Cell differentiation and motion determine the Bacillus subtilis biofilm morphological evolution under the competitive growth.

The growth discrepancy of Bacillus subtilis biofilms along different directions under the competitive growth drive the formation of anisotropic biofilm morphology directly. Two biofilms growing from two inoculating positions with different distances exhibit promoting or inhibiting growth behavior. Here we develop an optical imaging technology to observe the cell differentiation and the growth dynamics when the biofilm grows. It shows that the spatiotemporal distribution of different phenotypes affects the biofilm morphological evolution. We develop a program to calculate the velocity of cell motion within the biofilm, which is based on the feature point matching approach. We find the cell differentiation ununiformity in the neighboring region and its opposite region leads to the cell velocity difference in the competitive environment, the different cell motion further influences the biofilm morphology evolution. When biofilms grow with a long inoculating distance, there is always a gap between the them; when biofilms grow with a short inoculating distance, two biofilms gradually merge into a whole. Our work establishes a relationship between microscopic cells and macroscopic biofilm morphological which enables us to study the competitive growth process of biofilms from multiple perspectives.

Geophysical implications for the formation of the Tamu Massif-the Earth's largest single volcano-within the Shatsky Rise in the northwest Pacific Ocean.

Recent geophysical research programs survey the Tamu Massif within the Shatsky Rise oceanic plateau in the northwest Pacific Ocean to understand the formation of this immense volcano and to test the formation hypotheses of large igneous province volcanism. Massive sheet basalt flows are cored from the Tamu Massif, implying voluminous eruptions with high effusion rates. Seismic reflection data show that the Tamu Massif is the largest single volcano on Earth, characterized by a central volcanic shield with low-gradient flank slopes, implying lava flows emanating from its center and spreading massive area on the seafloor. Velocity model calculated from seismic refraction data shows that crustal thickness has a negative correlation with average velocity, implying a chemically anomalous origin of the Tamu Massif. Seismic refraction and reflection data reveal a complete crustal structure across the entire volcano, featured by a deep crust root with a maximum thickness of ∼30km, and Moho geometry is consistent with the Airy Isostasy. These recent findings provide evidence for the two end-member formation models: the mantle plume and the plate boundary. Both are supported by some results, but both are not fit with some either. Consequently, plume-ridge interaction could be a resolution that awaits future investigations.

Fabrication of hollow spheres by dry-gel conversion and its application in the selective hydrodesulfurization of FCC gasoline.

Hollow spheres were synthesized from MCM-41 solid spheres by dry-gel conversion. It was found that water amount has a major impact on the formation of hollow spheres. Transmission electron microscopy (TEM) images revealed that the hollow spheres are between 500 and 600 nm in size with a dense shell of ca. 100 nm. The synthesized hollow sphere sample was examined as a support for hydrodesulfurization catalyst. The sulfur removal was enhanced while olefin hydrogenation of FCC gasoline was suppressed, and thus, the octane value was preserved when the hollow spheres (Na type) were loaded with Ni and Mo oxides as catalyst.

[Catalytic removal of NO on modified precious catalyst].

The streams of waste gases containing NO from industries would cause seriously pollution on the environment if they are directly discharged without further purification. The property of removal of NO from the waste gas at lower temperature performed on platinum catalyst by reduction with NH3 was investigated. Experimental study showed that the precious catalyst, platinum, had good activity at low temperature and high selectivity of catalytic removal of NO from the waste gas by ammonia. However, its performance was affected by the sulfur compound, SO2, which was present in the waste gas. Results indicated that the performance of platinum supported catalyst could be improved with addition of lanthanides on it. The suitable compositions of the modified catalyst were 1:3.78:3.56 molar ratio of Pt:La:Ce in the experiment.