Analysis of the clinical profile and treatment efficiency of hyperlipidemic acute pancreatitis.

BACKGROUND: The incidence of hyperlipidemic acute pancreatitis (HLAP) has been increasing annually. However, population-based morbidity assessments need to be updated. Early, rapid, and effective lipid-lowering may minimize pancreatic injury and improve clinical prognosis. It is essential to choose the proper treatment. However, treatment options for HLAP are controversial, and there is no uniform treatment protocol. METHODS: In this retrospective study, 127 patients with hyperlipidemic severe acute pancreatitis (HL-SAP) were registered from January 2018 to December 2022 at the General Hospital of Ningxia Medical University. Medical and radiological records of hospitalized patients were collected to determine clinical features, severity, complications, mortality, recurrence rate, and treatment. Risk factors for HL-SAP were analyzed using multifactorial logistic regression. A propensity score matching method was used to compare the clinical outcomes of standard and plasma exchange therapies. RESULTS: In this research, the prevalence of HLAP increased about 1.6 times, and the prevalence of HL-SAP was 50.60%. HL-SAP occurs most often in people between the ages of 30 and 39. Amylase exceeded 110 U/L in 84.3% of patients and 330 U/L in only 47.2%. 83.5% of HL-SAP patients had fatty livers and high body mass index (BMI). A total of 48.0% of patients experienced organ failure, ICU treatment (55.1%), recurrence (33.1%), and death (21.3%). Between the hyperlipidemic group and the biliary group in terms of age, gender, BMI, fatty liver, pleural effusion, abdominal constriction syndrome (ACS), multiple organ dysfunction syndrome (MODS), length of hospital, medical costs, morbidity and mortality, triglyceride, cholesterol, creatinine, blood glucose, D-dimer, amylase, albumin, lactate dehydrogenase, serum phosphorus, serum calcium, oxygenation index, and recurrence rate were statistically significant (P < 0.05). High BMI (P = 0.0038, odds ratio (OR) = 1.336, 95%CI: 0.99-1.804), high C-reactive protein (CRP) (P = 0.022, OR = 1.011, 95%CI: 1.003-1.019), low calcium (P = 0.003, OR = 0.016, 95%CI. 0.001-0.239), low albumin (P = 0.012, OR = 0.045, 95%CI: -0.062-0.192), and high D-dimer (P = 0.041, OR = 0.619, 95%CI: 0.053-2.510) were risk factors for HL-SAP, according to multifactorial logistic regression analysis. Adjusted for propensity score matching (PSM), Serum triglyceride (TG) was significantly lower in both the standard treatment (P < 0.001) and plasma exchange (P < 0.001) groups at 48 h compared with the initial test after the attack. Clearance (83.20% ± 0.0% vs. 84.4% ± 0.0%, P = 0.531), length of hospital stay (19.9 ± 4.9 vs. 19.8 ± 11.1, P = 0.092), and death (26.3% vs. 23.6%, P = 0.791) showed no difference between the two groups. However, the difference in medical costs(P = 0.039)between the two groups was statistically significant. CONCLUSION: The incidence of HLAP exhibited a significant increase, remarkable severity, recurrent trend, and mortality. High BMI, high CRP, low calcium, low albumin, and high D-dimer are risk factors for HL-SAP. Compared with standardized treatment, plasma exchange does not improve the prognosis of HL-SAP patients, and standardized treatment is equally effective, safe, and low-cost in early treatment.

Role of Impurities in Kaolinite Intercalation and Subsequent Formation of Nanoscrolls.

Kaolinite (Kaol)-methanol (MeOH) compounds (Kaol-Me) are widely used as the starting materials for further intercalation. The conventional approach to prepare Kaol-Me compounds is to wash dimethyl sulfoxide (DMSO)-intercalated Kaol (Kaol-DMSO) for 16 days, and MeOH must be refreshed every day. Herein, we report a new and much more efficient method to prepare Kaol-Me from Kaol-DMSO by the promotion of AlCl3 under mild conditions, and the corresponding mechanism is investigated. The X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and X-ray fluorescence characterization results reveal that the electric double layer resulting from the impurities absorbed on the kaolinite surface prevents weakly polar molecules from entering the kaolinite interlayers, which is probably the key reason that MeOH must be refreshed daily in the preparation of Kaol-Me compounds. After being treated with HCl to remove the impurities, Kaol-Me-HCl was successfully intercalated by cetyltrimethyl ammonium bromide and subsequently predominantly curled into nanoscrolls.

Exploring choices of early nutritional support for patients with sepsis based on changes in intestinal microecology.

BACKGROUND: Sepsis exacerbates intestinal microecological disorders leading to poor prognosis. Proper modalities of nutritional support can improve nutrition, immunity, and intestinal microecology. AIM: To identify the optimal modality of early nutritional support for patients with sepsis from the perspective of intestinal microecology. METHODS: Thirty patients with sepsis admitted to the intensive care unit of the General Hospital of Ningxia Medical University, China, between 2019 and 2021 with indications for nutritional support, were randomly assigned to one of three different modalities of nutritional support for a total of 5 d: Total enteral nutrition (TEN group), total parenteral nutrition (TPN group), and supplemental parenteral nutrition (SPN group). Blood and stool specimens were collected before and after nutritional support, and changes in gut microbiota, short-chain fatty acids (SCFAs), and immune and nutritional indicators were detected and compared among the three groups. RESULTS: In comparison with before nutritional support, the three groups after nutritional support presented: (1) Differences in the gut bacteria (Enterococcus increased in the TEN group, Campylobacter decreased in the TPN group, and Dialister decreased in the SPN group; all P < 0.05); (2) different trends in SCFAs (the TEN group showed improvement except for Caproic acid, the TPN group showed improvement only for acetic and propionic acid, and the SPN group showed a decreasing trend); (3) significant improvement of the nutritional and immunological indicators in the TEN and SPN groups, while only immunoglobulin G improved in the TPN group (all P < 0.05); and (4) a significant correlation was found between the gut bacteria, SCFAs, and nutritional and immunological indicators (all P < 0.05). CONCLUSION: TEN is recommended as the preferred mode of early nutritional support in sepsis based on clinical nutritional and immunological indicators, as well as changes in intestinal microecology.

[Clinical characteristics and risk factors of early septic patients complicated with bloodstream infection].

OBJECTIVE: To analyze the clinical characteristics, risk factors and prognosis of early septic patients with bloodstream infection (BSI) in department of critical care medicine of Ningxia Medical University General Hospital. METHODS: Patients with sepsis admitted to department of critical care medicine of Ningxia Medical University General Hospital from November 1, 2019 to August 31, 2021 were included in a prospective observational study. Blood samples were collected for culture within 24 hours of sepsis diagnosis. General information, laboratory test indicators and blood culture results within 24 hours of sepsis diagnosis were recorded. Patients were followed up and prognostic indicators [mechanical ventilation time, length of intensive care unit (ICU) stay, and 28-day survival] were observed. According to blood culture results, patients were divided into BSI group and non-BSI group. Univariate and multivariate Logistic regression analysis were performed on the general clinical characteristics of patients in the two groups to screen the risk factors of early BSI in septic patients. Receiver operator characteristic curve (ROC) was drawn to evaluate the predictive value of risk factors for early BSI in septic patients. RESULTS: A total of 202 septic patients were included in this study, with 62 patients in BSI group and 140 patients in non-BSI group. The majority of patients in the BSI group were associated with abdominal infection (61.3%), and the majority of patients in the non-BSI group were associated with pulmonary infection (49.3%). A total of 76 strains were isolated from septic patients in BSI group, and the most common pathogens were Escherichia coli (26 strains, 34.2%), Klebsiella pneumoniae (11 strains, 14.4%), Enterococcus (7 strains, 9.2%), Bacteroides fragilis (6 strains, 7.9%) and Staphylococcus aureus (6 strains, 7.9%). There were no significant differences in mechanical ventilation time, the length of ICU stay and 28-day mortality between the BSI group and the non-BSI group. The difference of variables was statistically significant between two group according to Univariate analysis, which included body temperature, acute physiology and chronic health score II (APACHE II), use of antibiotics before admission to ICU, abdominal infection, hypersensitivity C-reactive protein (hs-CRP), serum creatinine (SCr), total bilirubin (TBil), platelet count (PLT), blood lactic acid (Lac) and hypercalcitonin (PCT). Multivariate analysis showed that low PLT [odds ratio (OR) = 1.004, P = 0.019], high Lac (OR = 1.314, P = 0.002), high body temperature (OR = 1.482, P = 0.027), concomitant abdominal infection (OR = 2.354, P = 0.040), no use of antibiotics before admission to ICU (OR = 2.260, P = 0.049) were independent risk factors for early BSI in septic patients. The area under ROC curve (AUC) of PLT, Lac, body temperature, abdominal infection and no use of antibiotics before admission to ICU for predicting early BSI in septic patients were 0.711, 0.686, 0.594, 0.592 and 0.590, respectively. Youden index was used to calculate the optimal cut-off values, which was PLT 122.50×109/L, Lac 2.95 mmol/L, body temperature 39.45 centigrade, respectively. The highest level of AUC was 0.754, the PI guidance group was expected to achieve PI the sensitivity was 75.8%, and the specificity was 68.8%, which were observed when the 5 items were combined. CONCLUSIONS: Early septic patients with BSI are more serious than those without BSI. Low PLT, high Lac, high temperature, concomitant abdominal infection and no use of antibiotics before admission to ICU are independent risk factors for early BSI in septic patients, and the combination of these five factors has good predictive value.

[Application value of lung ultrasound in the diagnosis and severity assessment of ventilator-associated pneumonia].

OBJECTIVE: To explore the value of bedside lung ultrasound in the early diagnosis and severity assessment of ventilator-associated pneumonia (VAP). METHODS: A prospective observational study was conducted in 60 patients with VAP (VAP group) and 62 patients without VAP (control group) who were admitted to department of intensive care unit of General Hospital of Ningxia Medical University from September 2018 to July 2020. The gender, age and underlying diseases of non-VAP group were matched with VAP group. The general clinical data such as gender, age, underlying diseases, department source of the patient, acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure assessment (SOFA) score were recorded. The body temperature, white blood cell count (WBC), procalcitonin (PCT), oxygenation index (PaO2/FiO2), alveolar artery oxygen differential pressure (PA-aDO2) were recorded. During mechanical ventilation, the patient's body temperature, WBC, sputum characteristics, and the change of the lung ultrasound were dynamically observed. With or without dynamic air bronchogram, lung ultrasound was considered to be positive as long as there were small subpleural consolidation or tissue-like sign. Ventilator-associated pneumonia lung ultrasound score (VPLUS) and lung ultrasound score (LUSS) were performed, and chest CT scan was completed on the same day. Use positive chest CT scan as the standard to evaluate the diagnostic efficacy of lung ultrasound, VPLUS score, and the combination of the two with PCT for VAP. LUSS was used to assess the severity of disease in patients with VAP. The correlation between LUSS and PaO2/FiO2, PA-aDO2, APACHE II score and SOFA score were analyzed. RESULTS: (1) General information: compared with non-VAP group, VAP group had more emergency surgery patients [51.7% (31/60) vs. 33.9% (21/62), P = 0.047], APACHE II score and SOFA score were significantly higher (APACHE II score: 15.4±5.7 vs. 13.4±3.4, P = 0.021; SOFA score: 8.8±4.2 vs. 6.3±3.3, P < 0.001), body temperature tended to rise (centigrade: 38.3±0.8 vs. 38.0±0.9, P = 0.054), more patients had airway purulent secretions [65.0% (39/60) vs. 41.9% (26/62), P = 0.011], and mechanical ventilation time and length of ICU stay were longer [mechanical ventilation time (days): 10.5 (6.6, 15.0) vs. 4.3 (3.0, 6.0), P < 0.001; length of ICU stay (days): 14.8 (9.0, 18.0) vs. 6.0 (4.0, 9.1), P < 0.001], 28-day mortality rate was higher [31.7% (19/60) vs. 9.7% (6/62), P = 0.003]. (2) Diagnostic efficacy evaluation: when lung ultrasound was positive, VPLUS ≥ 3 and PCT > 0.5 µg/L were used separately for the diagnosis of VAP, the sensitivity was 73.3%, 75.0%, 61.7%, respectively; the specificity was 80.6%, 58.1% and 59.7%, respectively; the 95% confidence interval (95%CI) was 0.685-0.842, 0.574-0.748, 0.514-0.694, respectively,all P < 0.05, positive lung ultrasound had good sensitivity and specificity. When positive lung ultrasound or VPLUS ≥ 3 were combined with PCT > 0.5 µg/L for tandem test, the specificity of VAP diagnosis was increased to 95.2% and 83.9%, respectively; but the specificity of VAP diagnosis of positive lung ultrasound combined with PCT > 0.5 µg/L was higher than VPLUS ≥ 3 combined with PCT > 0.5 µg/L (95.2% vs. 83.9%, P < 0.05). (3) Correlation analysis: LUSS showed a significant positive correlation with APACHE II and SOFA score (r values were 0.407, 0.399, P values were 0.001, 0.002, respectively), LUSS had no relation with PaO2/FiO2 and PA-aDO2 (r values were 0.189, -0.064, P values were 0.629, 0.149, respectively). CONCLUSIONS: Lung ultrasound can early detect VAP , and its diagnostic specificity is significantly improved when combined with PCT > 0.5 µg/L. LUSS is closely related to the severity of disease in VAP patients, therefore, lung ultrasound may be an effective method for early diagnosis and efficacy evaluation of VAP patients.

Classification and carbon structural transformation from anthracite to natural coaly graphite by XRD, Raman spectroscopy, and HRTEM.

Low-weight components of coal macromolecule were subjected to pyrolysis and condensation when magmatic rock intruded into coal measure, eventually, the residual condensed aromatic components can transform into microcrystalline graphite (coaly graphite). To study the structural transformation from anthracite to natural coaly graphite, ten samples with different graphitization degrees from Xinhua and Lutang of Hunan Province, China were characterized by organic geochemical analysis, X-ray diffraction (XRD), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM). The geochemical parameters (proximate and ultimate analyses) and structural features (XRD, Raman, and HRTEM) of the series naturally graphitized coals exhibit a progressive change as the samples' locations closing to the intrusion. The series naturally graphitized coal samples were classified into four categories, including anthracite, meta-anthracite, semi-graphite, and coaly graphite. But, single parameter cannot classify the series metamorphosed coals well, multi parameters including ash free-basis volatile matter, petrographic features, and carbon structural parameters (based on XRD and Raman spectroscopy) should be considered, additionally, the lattice fringe change observed under HRTEM from anthracite to coaly graphite can verify for the classification. The relatively lower metamorphic grade samples (anthracite and meta-anthracite) have small crystalline sizes, prominent disorders, and amorphous carbon structure, whereas the crystallite structure of highest grade samples (coaly graphite) is three-dimensional crystalline order (testified by XRD and HRTEM), indicating a totally structural transformation from amorphous carbon of anthracite to highly ordered crystalline carbon of coaly graphite in the course of natural graphitization. The carbon structural evolution of coal under natural graphitization process will probably be helpful for synthetic graphite using coal to replace the expensive petroleum coke in the future.

An efficient method to prepare aluminosilicate nanoscrolls under mild conditions.

The conventional approach to exfoliate kaolinite to form aluminosilicate nanoscrolls is very time-consuming. Herein, we report a novel method to prepare aluminosilicate nanoscrolls from kaolinite by catalysis of AlCl3 under mild conditions. This method is highly efficient, environmentally friendly, and can be easily scaled up for mass production.

TEG in the monitoring of coagulation changes in patients with sepsis and the clinical significance.

Application values of thromboelastography (TEG) in dynamic monitoring of coagulation parameters of sepsis patients were investigated. Eighty-one patients with sepsis who were admitted to the ICU department of the General Hospital of Ningxia Medical University from April 1, 2015 to December 31, 2015 were collected. Clinical data of the patients were collected. Data were compared using 5 grouping methods: i) the 81 patients were divided into the sepsis group (n=45) and sepsis shock group (n=36); ii) patients were divided into two groups: group A (APACHE II score ≤13, n=51); group B (APACHE II score >13, n=30); iii) according to Disseminated Intravascular Coagulation Diagnosis Integral System (CDSS), patients were divided into non-disseminated intravascular coagulation (DIC) group (CDSS <7 points) and DIC group (CDSS ≥7 points); TEG indexes were compared between the two groups; iv) correlation between TEG indexes and Sequential Organ Failure Assessment (SOFA) scores was analyzed; v) patients were divided into survival group and non-survival group and correlations between TEG indicators and prognosis were analyzed. At 6 h after ICU entry, compared with sepsis group, R value and K time were significantly increased, LY30 was also increased, while MA value, coagulation index (CI), and α angle were significantly decreased in the septic shock group (P<0.05). At 6 h after ICU entry, compared with sepsis group, R value and K time were significantly increased, while MA value, CI, and α angle were significantly decreased in the septic shock group (P<0.05). Compared with the non-DIC group, the DIC group had prolonged K time, decreased α angle, increased R value, and decreased CI and MA value (P<0.05). With increase of SOFA scores, R value and K value increased significantly, and α angle, MA value, and CI decreased significantly (P<0.05). According to TEG, platelet function and fibrinogen function of DIC patients were significantly reduced, and the body showed hypocoagulability.

Hierarchical Structure Kaolinite Nanospheres with Remarkably Enhanced Adsorption Properties for Methylene Blue.

Kaolinite nanospheres with hierarchical structures were synthesized via dehydration-rehydration technique through calcined-hydrothermal route. The microstructure of samples were characterized and analyzed by diverse techniques. The results show that after hydrothermal treatment, the layered pseudo-hexagonal kaolinite particles transformed to hierarchical structure nanospheres. The hierarchical structures exhibit large specific surface area of 157.1 m2 g-1 and narrow mesoporous size distribution. The adsorption properties of kaolinite nanospheres were systematically investigated by the removal of methylene blue (MB) from water. It was found that the nanospheres can rapidly adsorb MB with a higher adsorption capacity (184.9 mg/g), and adsorption data followed Langmuir isotherm model and pseudo-second-order kinetic model. Furthermore, the adsorbent can be regenerated by washing with methanol-HCl solution and shown removal efficiency of more than 95% up to 4 cycles.

Colquhounia Root Tablet Protects Rat Pulmonary Microvascular Endothelial Cells against TNF-α-Induced Injury by Upregulating the Expression of Tight Junction Proteins Claudin-5 and ZO-1.

BACKGROUND: There are currently limited effective pharmacotherapy agents for acute lung injury (ALI). Inflammatory response in the lungs is the main pathophysiological process of ALI. Our preliminary data have shown that colquhounia root tablet (CRT), a natural herbal medicine, alleviates the pulmonary inflammatory responses and edema in a rat model with oleic acid-induced ALI. However, the potential molecular action mechanisms underlining its protective effects against ALI are poorly understood. This study aimed to investigate the effects and mechanism of CRT in rat pulmonary microvascular endothelial cells (PMEC) with TNF-α-induced injury. METHODS: PMECs were divided into 6 groups: normal control, TNF-α (10 ng/mL TNF-α), Dex (1×10-6 M Dex + 10 ng/mL TNF-α), CRT high (1000 ng/mL CRT + 10 ng/mL TNF-α), CRT medium (500 ng/mL CRT + 10 ng/mL TNF-α), and CRT low group (250 ng/mL CRT + 10 ng/mL TNF-α). Cell proliferation and apoptosis were detected by MTT assay and flow cytometry. Cell micromorphology was observed under transmission electron microscope. The localization and expression of tight junction proteins Claudin-5 and ZO-1 were analyzed by immunofluorescence staining and Western blot, respectively. RESULTS: TNF-a had successfully induced an acute endothelial cell injury model. Dex and CRT treatments had significantly stimulated the growth and reduced the apoptosis of PMECs (all p < 0.05 or 0.01) and alleviated the TNF-α-induced cell injury. The expression of Claudin-5 and ZO-1 in Dex and all 3 CRT groups was markedly increased compared with TNF-a group (all p < 0.05 or 0.01). CONCLUSION: CRT effectively protects PMECs from TNF-α-induced injury, which might be mediated via stabilizing the structure of tight junction. CRT might be a promising, effective, and safe therapeutic agent for the treatment of ALI.

Interfacial Structure and Interaction of Kaolinite Intercalated with N-methylformamide Insight from Molecular Dynamics Modeling.

The evolution of basal spacing and interfacial structure of kaolinite-N-methylformamide (NMF) complexes during the intercalation process were difficult to obtain using experimental methods. In present study, a series of kaolinite-NMF complex models with various numbers of NMF molecules in the interlayer space were constructed to mimic the progressive stage of the intercalation process of kaolinite intercalated by NMF. The MD simulations were performed on these models to explore the evolution of basal spacing and interfacial structure of kaolinite-NMF complexes during the intercalation process. It was found that the basal spacing of complex was stabilized at 11 Å during the intercalation process, where the molecular plane of NMF oriented at small angles with respect to the interlayer surface with the C=O groups and N-H bonds pointing toward the octahedral and tetrahedral surfaces, respectively, due to the hydrogen bonding interactions. The basal spacing can be enlarged to larger values with the prerequisite of overcoming the energy barrier. With the increase of basal spacing during the intercalation process, the NMF were rearranged as a pillar with the molecular planes orienting at higher angles with respect to the interlayer surface, and then developed to disordered bilayer structure. For the interfacial interaction of kaolinite-NMF complex, both the octahedral surface and tetrahedral surface showed binding affinity to the NMF, which is the driving force for the intercalation of NMF in kaolinite. The octahedral surface displays stronger binding affinity to the NMF in terms of the H-bonds and energetics compared to the tetrahedral surface partially due to the highly active surface hydroxyl groups. The present study provides insight into the basal spacing evolution, and interfacial structure and interaction of kaolinite-NMF complexes, which can enhance the understanding of kaolinite intercalated by small molecules.

Molecular Structure and Decomposition Kinetics of Kaolinite/Alkylamine Intercalation Compounds.

Although the development of clay/polymer nanocomposites and their applications have attracted much attention in recent years, a thorough understanding of the structure and the decomposition mechanism of clay/polymer nanocomposites is still lacking. In this research, the intercalation of kaolinite (Kaol) with different alkylamines were investigated by X-ray diffracion (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetry and differential scanning calorimetry (TG-DSC). The results showed that the intercalation of Kaol/methanol compound with hexylamine (HA), dodecylamine (DA), and octadecylamine (OA) led to the expansion of the interlayer distance and resulted in the dominant basal diffraction at 2.86, 4.08, and 5.66 nm. The alky chains of HA, DA, and OA are tilted toward the Kaol surface in bilayer with an inclination angle of ~40°. The most probable mechanism function, activation energy E, and pre-exponential factor A were obtained by mutual authentication using KAS and Ozawa methods, itrative and Satava integral method. The average activation energy E of the three intercalation compounds are 104.44, 130.80, and 154.59 kJ mol-1, respectively. It shows a positive correlation with the alkyl chain length. The pre-exponential factor A was estimated to be 1.09 × 1015, 1.15 × 108, and 4.17 × 1021 s-1, respectively. The optimized mechanism function for the decomposition of alkylamine is G(α) = [(1-α) -1/3-1]2.

Molecular Dynamics Simulation of Basal Spacing, Energetics, and Structure Evolution of a Kaolinite-Formamide Intercalation Complex and Their Interfacial Interaction.

Molecular dynamics simulations were performed on kaolinite-formamide complex models with various numbers of formamide molecules loaded in the kaolinite interlayer to explore the basal spacing, energetics, and structure evolution of the kaolinite-formamide complex during the intercalation process. Additionally, the interfacial interactions of formamide with kaolinite interlayer surfaces were calculated. The calculation revealed that the basal spacing of kaolinite was enlarged to 9.6 Å at the beginning of intercalation. Formamide was arranged as a monolayer structure in the kaolinite interlayer with the molecular plane oriented at small angles with respect to the interlayer surface. With continuous intercalation, the basal spacing readily reached a stable stage at 10.6 Å, where formamide rearranged its structure by rotating the molecule plane along the C-N bond that was parallel to the interlayer surface, which resulted in the molecular plane orienting at higher angles with respect to the interlayer surface. During this process, the C═O groups oriented toward the hydroxyl groups on the interlayer octahedral surface, and one of N-H bonds progressively pointed toward the basal oxygens on the opposing interlayer tetrahedral surface. Continuous intercalation can enlarge the basal spacing to more than 14 Å with the prerequisite of overcoming the energy barrier, and then formamide evolved to a disordered bilayer structure in the kaolinite interlayer. The affinity of kaolinite interlayer surfaces for formamide motivated the intercalation process. The octahedral surface displayed a relatively larger affinity toward formamide compared to the tetrahedral surface partially due to the presence of hydroxyl groups that are more active in the intermolecular interactions with formamide.

Mechanism Responsible for Intercalation of Dimethyl Sulfoxide in Kaolinite: Molecular Dynamics Simulations.

Intercalation is the promising strategy to expand the interlayer region of kaolinite for their further applications. Herein, the adaptive biasing force (ABF) accelerated molecular dynamics simulations were performed to calculate the free energies involved in the kaolinite intercalation by dimethyl sulfoxide (DMSO). Additionally, the classical all atom molecular dynamics simulations were carried out to calculate the interfacial interactions between kaolinite interlayer surfaces and DMSO with the aim at exploring the underlying force that drives the DMSO to enter the interlayer space. The results showed that the favorable interaction of DMSO with both kaolinite interlayer octahedral surface and tetrahedral surface can help in introducing DMSO enter kaolinite interlayer. The hydroxyl groups on octahedral surface functioned as H-donors attracting the S=O groups of DMSO through hydrogen bonding interaction. The tetrahedral surface featuring hydrophobic property attracted the methyl groups of DMSO through hydrophobic interaction. The results provided a detailed picture of the energetics and interlayer structure of kaolinite-DMSO intercalate.

[Expressions of microRNA-127-5p in bronchoalveolar lavage fluid of patients with severe pneumonia and its diagnostic value].

OBJECTIVE: To observe differential expressions of microRNA-127-5p (miR-127-5p) in bronchoalveolar lavage fluid (BALF) of patients with severe pneumonia and the value of miR-127-5p in the diagnosis of severe pneumonia. METHODS: Thirty severe pneumonia patients and 10 non-respiratory infection patients who needed mechanical ventilation after surgery admitted to Department of Critical Care Medicine of General Hospital of Ningxia Medical University from January to December in 2015 were enrolled, whose specimens of BALF were collected. The differential expressions of miRNA in BALF of patients in both groups were screened by miRNA chip technique to preliminarily establish miRNA differential expression profiles in BALF of severe pneumonia, and the miRNAs which were up-regulated and down-regulated were screened out. The expression levels of miR-127-5p were determined using a real-time fluorescent quantitative polymerase chain reaction (PCR). The value of miR-127-5p expression in the diagnosis of severe pneumonia was evaluated with receiver-operating characteristic curve (ROC). RESULTS: All of the 40 patients were enrolled in the final analysis. Differential expression spectrum of miRNA in severe pneumonia patients was initially built, in which 40 miRNAs were up-regulated and 113 miRNAs were down-regulated. Compared with non-respiratory infection patients, the expressions of miR-127-5p were significantly lowered in severe pneumonia patients (2-Δ ΔCT: 0.578±0.226 vs. 1.004±0.337) with statistical difference (t = 4.552, P = 0.000). ROC curve analysis showed that the area under ROC curve (AUC) of miR-127-5p for diagnosis of severe pneumonia was 0.855 [95% confidence interval (95%CI) = 0.721-0.989, P = 0.001], with the optimal sensitivity and specificity of 86.7% and 70.0% respectively with 0.840 as the critical value, and the positive likelihood ratio was 2.89, the negative likelihood ratio was 0.19. CONCLUSIONS: miR-127-5p in BALF could be used as a new biomarker for the diagnosis of severe pneumonia.

Electrokinetic Energy Conversion in Self-Assembled 2D Nanofluidic Channels with Janus Nanobuilding Blocks.

Inspired by the microstructure of nacre, material design, and large-scale integration of artificial nanofluidic devices step into a completely new stage, termed 2D nanofluidics, in which mass and charge transportation are confined in the interstitial space between reconstructed 2D nanomaterials. However, all the existing 2D nanofluidic systems are reconstituted from homogeneous nanobuilding blocks. Herein, this paper reports the bottom-up construction of 2D nanofluidic materials with kaolinite-based Janus nanobuilding blocks, and demonstrates two types of electrokinetic energy conversion through the network of 2D nanochannels. Being different from previous 2D nanofluidic systems, two distinct types of sub-nanometer- and nanometer-wide fluidic channels of about 6.8 and 13.8 Å are identified in the reconstructed kaolinite membranes (RKM), showing prominent surface-governed ion transport behaviors and nearly perfect cation-selectivity. The RKMs exhibit superior capability in osmotic and hydraulic energy conversion, compared to graphene-based membranes. The mineral-based 2D nanofluidic system opens up a new avenue to self-assemble asymmetric 2D nanomaterials for energy, environmental, and healthcare applications.

Mechanism Associated with Kaolinite Intercalation with Urea: Combination of Infrared Spectroscopy and Molecular Dynamics Simulation Studies.

Intercalation of urea in kaolinite was investigated using infrared spectroscopy and molecular dynamics simulation. Infrared spectroscopic results indicated the formation of hydrogen bonds between urea and siloxane/alumina surfaces of kaolinite. The carbonyl group (-C=O) of urea acted as H-acceptors for the hydroxyl groups on alumina surfaces. The amine group (-NH2) of urea functioned as H-donors interacting with basal oxygens on siloxane surfaces and/or the oxygens of hydroxyl groups on alumina surfaces. The H-bonds of urea formed with kaolinite surfaces calculated directly from molecular dynamics simulation was consistent with the infrared spectroscopic results. Additionally, MD simulations further provided insight into the interaction energies of urea with the kaolinite interlayer environment. The calculated interaction energies of urea molecules with kaolinite alumina and siloxane surfaces suggest that the intercalation of urea within kaolinite interlayers is energetically favorable. The interaction energy of urea with alumina surfaces was greater than that with siloxane surfaces, indicating that the alumina surface plays a primary role in the intercalation of kaolinite by urea. The siloxane surfaces function as H-acceptors to facilitate the intercalation of urea. The present study offers a direct view of the specific driving force involved in urea intercalation in kaolinite. The results obtained can help develop appropriate protocol to intercalate and delaminate clay layers for clay-based applications and products.

Thermodynamic Mechanism and Interfacial Structure of Kaolinite Intercalation and Surface Modification by Alkane Surfactants with Neutral and Ionic Head Groups.

Intercalation and surface modification of clays with surfactants are the essential process to tailor the clays' surface chemistry for their extended applications. A full understanding of the interaction mechanism of surfactants with clay surfaces is crucial to engineer clay surfaces for meeting a particular requirement of industrial applications. In this study, the thermodynamic mechanism involved in the intercalation and surface modification of methanol preintercalated kaolinite by three representative alkane surfactants with different head groups, dodecylamine, cetyltrimethylammonium chloride (CTAC), and sodium stearate, were investigated using the adaptive biasing force accelerated molecular dynamics simulations. In addition, the interaction energies of surfactants with an interlayer environment (alumina surface, siloxane surface, and interlayer methanol) of methanol preintercalated kaolinite were also calculated. It was found that the intercalation free energy of CTAC with a cationic head group was relatively larger than that of stearate with an anionic head group and dodecylamine with a neutral head group. The attractive electrostatic and van der Waals interactions of surfactants with an interlayer environment contributed to the intercalation and surface modification process with the electrostatic force playing the significant role. This study revealed the underlying mechanism involved in the intercalation and surface modification process of methanol preintercalated kaolinite by surfactants, which can help in further design of kaolinite-based organic clays with desired properties for specific applications.

Molecular-Level Investigation of the Adsorption Mechanisms of Toluene and Aniline on Natural and Organically Modified Montmorillonite.

The present work reports the adsorption mechanisms of aniline and toluene in dry and hydrated montmorillonite (MMT-Na and MMT-Na-W) and tetramethylammonium-cation-modified MMT (MMT-TMA) as determined through density functional theory. These theoretical investigations explicitly demonstrate that cation-π interactions between Na(+)/TMA(+) cations and aromatics play the key role in adsorption of organics over MMT-Na and MMT-TMA. Weak hydrogen bonds between the H atoms of organics and basal O atoms of tetrahedral silicate also stabilize the location of organics. The combination of interactions between water and basal O atoms and between organics and water molecules in hydrated MMT complexes strengthens the adsorption of organics on MMT, resulting in higher formation energies in hydrated organically intercalated MMTs than in the corresponding dry complexes. The adsorption of organics also changes frontier orbital distributions and consequently promotes the preferential occurrence of reactions on the organics rather than on the MMT layers. These adsorption mechanisms predicted by theoretical investigation can be used to explicate the adsorption of aromatic organics on aluminosilicates with different external environment.