Exploring the genuine psychological experiences of novice nurses at emergency resuscitation events: A qualitative interview study.

Purpose: An emergency rescue situation is an inevitable challenge in medical work, requiring collaborative efforts from healthcare professionals. Due to a lack of practical experience, novice nurses may encounter difficulties in successfully managing emergency resuscitation events. This study aimed to analyse the authentic psychological experiences of novice nurses participating in emergency resuscitation events by exploring applicable coping methods and management strategies. Methods: This study utilized a hermeneutic phenomenological qualitative research method. We employed purposive sampling to select 27 Novice nurses from West China Hospital of Sichuan University for face-to-face semistructured interviews. Data collection for this study was conducted from November 2023 to January 2024. The interviews were fully audio-recorded and transcribed verbatim. The data were coded, categorized and summarized with the help of Nvivo 20.0 software based on the interpretation of phenomenological research methods. Thematic analysis was performed to deeply analyse and extract corresponding themes. The COREQ criteria were used to guide the reporting of this study. Results: The authentic psychological experiences of novice nurses participating in emergency rescue events mainly include six aspects: lack of rescue knowledge reserves and related abilities, psychological and emotional changes, psychological stress after the rescue, rational arrangement of manpower, team cooperation, and postevent reflection and learning. Their authentic psychological experiences directly affect whether novice nurses can effectively respond to emergency rescue events. Conclusions: This study suggested enhancing novice nurses' knowledge, improving their resuscitation skills, and improving their psychological well-being during resuscitation events. It advocates for organized staffing, effective teamwork, and robust support systems to empower novice nurses and improve their overall capabilities in emergencies. These findings offer valuable insights for future research in this area.

Effects of sitting position on ventilation distribution determined by electrical impedance tomography in ventilated ARDS patients.

OBJECTIVE: The study aimed to evaluate the improvements in pulmonary ventilation following a sitting position in ventilated ARDS patients using electrical impedance tomography. METHODOLOGY: A total of 17 patients with ARDS under mechanical ventilation participated in this study, including 8 with moderate ARDS and 9 with severe ARDS. Each patient was initially placed in the supine position (S1), transitioned to sitting position (SP) for 30 min, and then returned to the supine position (S2). Patients were monitored for each period, with parameters recorded. MAIN OUTCOME MEASURES: The primary outcome included the spatial distribution parameters of EIT, regional of interest (ROI), end-expiratory lung impedance (ΔEELI), and parameters of respiratory mechanics. RESULTS: Compared to S1, the SP significantly altered the distribution in ROI1 (11.29 ± 4.70 vs 14.88 ± 5.00 %, p = 0.003) and ROI2 (35.59 ± 8.99 vs 44.65 ± 6.97 %, p ＜ 0.001), showing reductions, while ROI3 (39.71 ± 11.49 vs 33.06 ± 6.34 %, p = 0.009), ROI4 (13.35 ± 8.76 vs 7.24 ± 5.23 %, p ＜ 0.001), along with peak inspiratory pressure (29.24 ± 3.96 vs 27.71 ± 4.00 cmH2O, p = 0.036), showed increases. ΔEELI decreased significantly ventrally (168.3 (40.33 - 189.5), p ＜ 0.0001) and increased significantly dorsally (461.7 (297.5 - 683.7), p ＜ 0.0001). The PaO2/FiO2 ratio saw significant improvement in S2 compared to S1 after 30 min in the seated position (108 (73 - 130) vs 96 (57 - 129) mmHg, p = 0.03). CONCLUSIONS: The sitting position is associated with enhanced compliance, improved oxygenation, and more homogenous ventilation in patients with ventilated ARDS compared to the supine position. IMPLICATIONS FOR CLINICAL PRACTICE: It is important to know the impact of postural changes on patient pulmonary ventilation in order to standardize safe practices in critically ill patients. It may be helpful in the management among ventilated patients.

The effect of biofeedback on nonneurological dysfunctional voiding in children: A meta-analysis and systematic review.

OBJECTIVE: This study was conducted to investigate the effect of biofeedback (BF) on the rehabilitation of children with nonneurological dysfunctional voiding (NDV). METHODS: RCTs were retrieved from various databases (published from inception to February 29, 2024). The effects of the BF and non-BF treatments were compared. A random-effects model was used to evaluate the combined data. RESULTS: Meta-analysis revealed that BF increased the maximum urinary flow rate (SMD = 3.78, 95% CI 1.33∼6.22), improved urination time (SMD = 5.88, 95% CI 3.75∼8.01), and reduced the postvoid residual (SMD = -19.18, 95% CI -27.03∼-11.33) and urinary tract infection incidence (RR = 0.43, 95% CI 0.21∼0.87). Electromyogram activity (RR = 0.46, 95% CI 0.25∼0.84) and abnormal urination patterns (RR = 0.51, 95% CI 0.35∼0.74) improved, with effects persisting for more than 1 year. However, the effect of BF on the mean urinary flow rate in children with NDV was significant only after 1 year of follow-up (SMD = 1.90, 95% CI 0.87∼2.92). CONCLUSION: Existing evidence indicates that BF can enhance urinary parameters and patterns in children with NDV. However, its effectiveness in addressing constipation, daytime urinary incontinence, and nocturnal urinary incontinence is not substantial. High-quality randomized controlled trials can offer additional insights.

The performance of a combination of heparin-binding protein with other biomarkers for sepsis diagnosis: an observational cohort study.

BACKGROUND: HBP, a novel biomarker released from neutrophils, may induce inflammatory responses and exacerbate vascular permeability, representing the pathophysiological characteristics of sepsis and septic shock. However, it remains uncertain whether the combination of HBP with other biomarkers yields enhanced diagnostic capacity for sepsis. We hypothesized that measurements included IL-6·IL-8·HBP, IL-6·IL-8·HBP/ALB and HBP/ALB which based on HBP will improve its diagnostic efficacy and even better than the traditional infection biomarkers. METHODS: Between July 2021 and June 2022, we carried out a comprehensive, multi-center, observational cohort study spanning six leading tertiary hospitals located in Heilongjiang Province, China. Patients were stratified into three categories based on the severity of infection: non-sepsis, sepsis, and septic shock. We collected clinical and laboratory data, along with infection and inflammation biomarkers, for analysis. RESULTS: A total of 195 patients were enrolled. Among the three groups, patients with septic shock (n = 75, 38.5%) had significantly higher baseline levels of HBP, WBC, Lac, CRP, PCT, IL-6, IL-8, and IL-10 compared to non-sepsis patients (n = 43, 22.0%) and sepsis patients (n = 77, 39.5%), with statistically significant differences (p < 0.05) observed for all parameters. When compared to SOFA score and traditional markers of CRP, PCT, IL-6 and IL-8, the combined indexes of IL-6·IL-8·HBP and IL-6·IL-8·HBP/ALB demonstrated significantly improved diagnostic performance for sepsis and septic shock (AUC 0.911 and 0.902 respectively, p < 0.001). CONCLUSIONS: The combined measurements of IL-6·IL-8·HBP and IL-6·IL-8·HBP/ALB can augment the diagnostic capacity of HBP for sepsis, and offer reliable early supplementary indicators to traditional biomarkers for assessing disease severity in patients with infection.

Comparison of the Duhamel Procedure and Transanal Endorectal Pull-through Procedure in the Treatment of Children with Hirschsprung's Disease: A Systematic Review.

Objective: To compare the Duhamel and transanal endorectal pull-through (TERPT) procedures in the treatment of children with Hirschsprung's disease. METHODS: Studies comparing the Duhamel and TERPT procedures were included until 22 July 2023. R software (version 4.3.0) was used to perform the meta-analysis. RESULTS: Ten studies with a sum of 496 patients were included. The length of postoperative hospital stay and incidence of postoperative constipation were longer and higher after the Duhamel procedure than the TERPT procedure (p < 0.0001 and p = 0.0041, respectively). The incidence of postoperative anastomotic stricture was higher after the TERPT procedure than the Duhamel procedure (p = 0.0015). No significant differences were found in the incidence of postoperative fecal continence, fecal incontinence/soiling, anastomotic leak, or ileus between these two procedures. The operation time seemed to be similar for both procedures, but it became longer for the Duhamel procedure than the TERPT procedure after sensitivity analysis. While the incidence of postoperative enterocolitis seemed to be higher after the TERPT procedure, it became similar for both procedures in the subgroup analysis. CONCLUSIONS: The Duhamel procedure seems to be associated with a longer length of postoperative hospital stay, a higher incidence of postoperative constipation, and a lower incidence of postoperative anastomotic stricture than the TERPT procedure. However, the effect of these two procedures on the operation time and the incidence of postoperative enterocolitis remains unclear.

Effects of illness perception on negative emotions and fatigue in chronic rheumatic diseases: Rumination as a possible mediator.

BACKGROUND: Illness perception has long been hypothesized to be linked to psychological well-b eing in patients with rheumatic diseases, although substantial evidence is lacking, and the contribution of ruminative coping style to this relationship is unclear. AIM: To investigate the roles of illness perception and rumination in predicting fatigue and negative emotions in patients with chronic rheumatic diseases. METHODS: Illness perception, rumination, fatigue and negative emotions (i.e. depression, anxiety and stress) were assessed by the Illness Perception Questionnaire-Revised, Stress Reactive Rumination Scale, Multidimensional Assessment of Fatigue, and the Depression, Anxiety and Stress Scale respectively. Multivariate regression analysis, the Sobel test, and the bootstrap were used to identify the mediating effect of rumination. RESULTS: All five subscales of illness perception, including perceived illness identity, chronicity, cyclical nature, consequences and coherence of illness, were significantly associated with fatigue and negative emotions. In mediational analysis, rumination was found to mediate three components of illness perception (the identity, cyclical nature and consequences of illness) and negative emotions/fatigue. CONCLUSION: Perceived identity, cyclical nature, and consequences of illness are significantly associated with fatigue and negative emotions in patients with chronic rheumatic diseases and these associations are mediated by rumination. Our findings suggest that psychological intervention should target rumination to improve physical and emotional well-being of patients with chronic rheumatic diseases.

U-shaped association between serum albumin and pediatric intensive care unit mortality in critically ill children.

Introduction: The detailed association between albumin levels and mortality has not been studied in critically ill children. The aim of this study was to reveal an association between albumin levels in detail and mortality in critically ill children. Materials and methods: We retrospectively collected data from children admitted to four pediatric intensive care units (PICUs) in China between January 2015 and October 2020. Restricted cubic spline curves based on logistic regression models were generated to evaluate the detailed associations between serum albumin levels and PICU mortality. Threshold effect analysis was performed using two piecewise regression models. Results: The study included 9,123 children. The overall mortality was 5.3%. The detailed association between serum albumin levels and the risk of mortality followed a U-shape. The risk of mortality decreased with increasing serum albumin levels (OR = 0.919; 95% CI: 0.886, 0.954) in children with serum albumin levels < 43.2 g/L and increased with increasing serum albumin levels (OR = 1.174; 95% CI: 1.044, 1.316) in children with serum albumin levels ≥ 43.2 g/L. Conclusion: There was a U-shaped association between serum albumin levels and mortality in critically ill children in the PICU.

Maternal and Perinatal Risk Factors for Infantile Hemangioma: A Matched Case-Control Study with a Large Sample Size.

INTRODUCTION: Infantile hemangioma (IH) is the most common benign tumor in infancy, but information about its pathogenesis is limited. The aim of this study was to determine maternal and perinatal risk factors for IH. METHODS: A total of 1033 IH patients were enrolled in the study between 2017 and 2020. IH patients were matched with controls by sex. Trained investigators collected detailed information from the participants. Logistic regression models were used for multivariate analysis. RESULTS: The statistical analysis demonstrated that miscarriage history (odds ratio [OR] = 4.275; 95% confidence interval [CI] [3.195, 5.720]), anemia in pregnancy (OR = 4.228; 95% CI [3.083, 5.799]), preterm premature rupture of membranes (PPROM) (OR = 3.182; 95% CI [1.359, 7.454]), placenta previa (OR = 2.440; 95% CI [1.787, 3.333]), threatened miscarriage (OR = 2.290; 95% CI [1.726, 3.039]), premature rupture of membranes (PROM) (OR = 1.785; P < 0.05), progesterone use (OR = 1.614; P < 0.001) and abnormal amniotic fluid volume (OR = 1.499; P < 0.05) were independent risk factors for IH. Gestational diabetes mellitus (GDM) (OR = 0.607; 95% CI [0.464, 0.794]), multiple gestations (OR = 0.407; 95% CI [0.232, 0.713]), hypothyroidism (OR = 0.407; 95% CI [0.227, 0.730]) and uterine fibroids (OR = 0.393; 95% CI [0.250, 0.618]) may reduce the risk of IH. CONCLUSIONS: Maternal and perinatal factors are closely associated with IH occurrence. Our study provides reliable clues to guide further exploration of the pathogenesis of IH. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03331744. Infantile hemangioma is the most common benign tumor in children, which seriously affects appearance and function and even threatens life. The pathogenesis is not clear, a detailed case-control study of the maternal and perinatal periods with a large sample size will facilitate the development of individualized and precise treatment, early and timely interventions for high-risk children and improvement of prognosis. Our study found that miscarriage history, anemia in pregnancy, preterm premature rupture of membranes (PPROM), placenta previa, threatened miscarriage, premature rupture of membranes (PROM), progesterone use and abnormal amniotic fluid volume were independent risk factors for IH.

Au Modified F-TiO2 for Efficient Photocatalytic Synthesis of Hydrogen Peroxide.

In this work, Au-modified F-TiO2 is developed as a simple and efficient photocatalyst for H2O2 production under ultraviolet light. The Au/F-TiO2 photocatalyst avoids the necessity of adding fluoride into the reaction medium for enhancing H2O2 synthesis, as in a pure TiO2 reaction system. The F- modification inhibits the H2O2 decomposition through the formation of the ≡Ti-F complex. Au is an active cocatalyst for photocatalytic H2O2 production. We compared the activity of TiO2 with F- modification and without F- modification in the presence of Au, and found that the H2O2 production rate over Au/F-TiO2 reaches four times that of Au/TiO2. In situ electron spin resonance studies have shown that H2O2 is produced by stepwise single-electron oxygen reduction on the Au/F-TiO2 photocatalyst.

Comparison of PICU Cost and Severity-Adjusted Cost Between Patients With SIRS-Defined Sepsis and Those With Age-Adapted SOFA-Defined Sepsis.

Background: The 2005 International Pediatric Sepsis Consensus definition is considered to lack specificity and may lead to the admission of low-risk patients to the pediatric intensive care unit (PICU). The aim of this study was to compare the PICU cost and the severity-adjusted cost between patients with sepsis defined by the 2005 International Pediatric Sepsis Consensus and those diagnosed using the age-adapted Sepsis-3 criteria. Methods: Septic children identified by the 2005 Consensus were screened for enrollment. The enrolled children were stratified into two subgroups using the age-adapted Sepsis 3.0 definition. A comparison was made between the subgroups of sepsis 3.0-defined children and non-sepsis 3.0-defined septic children. The Severity Adjusted ICU Cost (SAIC) was used to evaluate the case-mixed severity-adjusted costs of the study population. Coefficients in linear regression analyses in subgroups were calculated for presenting variation of PICU costs for every unit change of PRISM score. Results: A total of 397 children were enrolled. The PICU length of stay was longer in the sepsis 3.0 group than in the non-sepsis 3.0 group [median (IQR), 9.0 (5.0, 15.0) vs. 6.0 (3.0, 9.0); P < 0.001]. Pediatric risk of mortality (PRISM) scores and mortality were significantly higher in sepsis 3.0-defined septic patients. The total costs and daily costs in the PICU were both significantly lower in the non-sepsis 3.0 group (P < 0.001). The severity-adjusted ICU cost in the non-sepsis 3.0 group was lower than that in the sepsis 3.0 group [median (IQR), 7,125 (3,588, 11,134) vs. 9,364 (5,680, 15,876); P = 0.001]. There was no significant difference among the regression coefficients. Conclusions: The 2005 International Pediatric Sepsis Consensus definition does not lead to more PICU costs after considering illness severity. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT03598127.

Central venous catheters misplaced in paraspinal veins: A systematic literature review based on case reports.

BACKGROUND: Paraspinal vein misplacement is an uncommon complication of central venous catheterization via lower extremities, most of which have been reported in case reports. AIM: To determine the clinical characteristics of paraspinal vein misplacement. DESIGN: This was a systematic review. METHODS: A systematic literature search in the PubMed, EMBASE, Scopus, and Web of Science databases was performed from their inception to 18 June 2019. Case reports and small case series describing central venous catheter misplacement in the paraspinal vein were included. Data on the catheterization procedure, catheter tip position, complications, and radiographic features of misplacement were extracted. RESULTS: Thirty studies with a total of 36 patients were included. The ascending lumbar vein accounted for the majority of misplacements (n = 30), followed by the lumbar vein (n = 4), iliolumbar vein (n = 1), and vertebral venous plexus (n = 1). Six patients had eventful catheterization procedures. Twenty-six patients experienced misplacement-induced complications, of whom seven died. The most common complications included cerebrospinal fluid abnormalities, neurological symptoms, and deteriorated respiration. Among the entire case cohort, the onset of complications was the primary sign that alerted medical staff to misplacement (n = 23). The typical radiographic characteristics were posterior deviation of the catheter course overlapping with the spine on lateral X-rays and a bend, kink, or hump in the catheter course on anteroposterior X-rays at the L4 to L5 levels. CONCLUSIONS: Nurses should be aware of this particular complication if a patient who has undergone catheterization via a lower extremity presents deterioration of neurological function and respiration. RELEVANCE TO CLINICAL PRACTICE: Lateral X-ray radiography is an effective method to verify misplacement and is recommended as routine practice during catheterization via lower extremities.

Learning curve of robot-assisted choledochal cyst excision in pediatrics: report of 60 cases.

BACKGROUND: Little data are available to assess the learning curve for robot-assisted surgery on choledochal cysts. The aim of this current study is to investigate the characteristics of the learning curve for robot-assisted choledochal cyst excisions using the da Vinci (SI) surgical system in pediatrics. METHODS: A retrospectively collected database comprising all medical records of the first 60 consecutive patients undergoing a robot-assisted choledochal cyst excision and Roux-en-Y hepaticojejunostomy using the da Vinci (SI) surgical system performed by one individual surgeon was studied. Baseline information and postoperative outcomes were collected and then learning curves were analyzed using the cumulative sum (CUSUM) method. Patients were divided into two groups including group A and group B according to the cutoff points of the learning curve. Intraoperative characteristics and short-term outcomes were compared between the two groups. RESULTS: CUSUM plots revealed that the cutoff point of the learning curve was 14 cases. Comparison of the operative time between the two groups revealed that the total operative time (203.71 ± 15.27, 171.28 ± 3.62 min, P < 0.001), docking time (23.79 ± 5.81, 14.50 ± 0.98 min, P < 0.001), and console time (151.86 ± 9.77, 129.15 ± 2.96 min, P < 0.001) were decreased significantly. The intraoperative bleeding (20.36 ± 7.46 vs. 20.43 ± 9.18, P = 0.977), time to taking water (2.89 ± 0.22 vs. 3.04 ± 0.34, P = 0.115), time to starting solids diet (3.73 ± 0.17 vs. 3.79 ± 0.26, P = 0.387), hospital stay (7.51 ± 1.12 vs. 7.54 ± 0.95, P = 0.910), and the postoperative complications did not differ significantly between the two groups. CONCLUSIONS: The learning curve for the robot-assisted choledochal cyst excision and Roux-en-Y hepaticojejunostomy in children is 14 cases. This learning curve can be used as the basis for performance guidance during training in future.

A ß-cyclodextrin Modified Graphitic Carbon Nitride with Au Co-Catalyst for Efficient Photocatalytic Hydrogen Peroxide Production.

Photocatalytic hydrogen peroxide (H2O2) production has attracted considerable attention as a renewable and environment-friendly method to replace other traditional production techniques. The performance of H2O2 production remains limited by the inertness of graphitic carbon nitride (CN) towards the adsorption and activation of O2. In this work, a photocatalyst comprising of ß-cyclodextrin (ß-CD)-modified CN with supporting Au co-catalyst (Au/ß-CD-CN) has been utilized for effective H2O2 production under visible light irradiation. The static contact angle measurement suggested that ß-CD modification increased the hydrophobicity of the CN photocatalyst as well as its affinity to oxygen gas, leading to an increase in H2O2 production. The rate of H2O2 production reached more than 0.1 mM/h under visible-light irradiation. The electron spin resonance spectra indicated that H2O2 was directly formed via a 2-electron oxygen reduction reaction (ORR) over the Au/ß-CD-CN photocatalyst.

A peripherally inserted central catheter misplacement into lateral thoracic vein: A case report.

INTRODUCTION: Central venous catheter applications and complications are closely related to the tip position. Previous studies have reported some rare cases of catheter misplacement. Here, we report a case of misplacement of a peripherally inserted central catheter into the lateral thoracic vein. CASE REPORT: A 56-year-old cancer patient underwent placement of a peripherally inserted central catheter through the left basilic vein under ultrasound-guided puncture. The catheterisation procedure was uneventful, so the catheter was believed to be in the superior vena cava. However, the post-anterior chest X-ray image revealed that after the catheter advanced towards the axilla, it turned downwards and outwards in the direction of the left lateral thoracic region, with the projection of the catheter tip giving the appearance of termination in the subcutaneous tissue of the lateral thoracic wall on the two-dimensional image. The catheter was then repositioned in the distal superior vena cava. DISCUSSION: Peripherally inserted central catheters can be potentially misplaced into the lateral thoracic vein because these catheters can pass through the orifice of the lateral thoracic vein which flows into the axillary vein. Some pathological cases and clinical conditions can cause dilatation of the lateral thoracic vein, which increases the probability of catheter misplacement. Three principles were proposed to avoid this rare complication: a comprehensive review of the patients' medical history, real-time image-guided catheterisation and routine radiographic identification of the tip position.

A novel "turn-on" fluorescent sensor for hydrogen peroxide based on oxidized porous g-C3 N4 nanosheets.

An oxidized, porous graphitic carbon nitride nanosheets (CNNs) was successfully obtained via a bottom-up approach. The inner filter effect (IFE) of Fe (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachlorideporphyrin pentachloride (FeTMPyP) on the CNNs results in fluorescence quenching of the CNNs due to the overlap of FeTMPyP absorbance band and CNNs emission band. It is interesting that the quenched fluorescence could be "turned on" in response to the participation of H2 O2 , which caused by decomposition of FeMPyP. In this study, for the first time, a porous fluorescence probe based on CNNs and FeTMPyP was designed and an excellent H2 O2 detection performance with a large detection range of 0.1 ~ 100 µM and a detection limit of 0.07 µM was achieved. Furthermore, the proposed method was successfully used for H2 O2 detection in RAW 264.7 cells.

What is the impact of the use of transanastomotic feeding tube on patients with esophageal atresia: a systematic review and meta-analysis.

BACKGROUND: The transanastomotic feeding tube (TAFT) is widely used around the world in patients with esophageal atresia (EA). However, the safety of the use of TAFT is still unknown and remains to be clarified. METHODS: The following electronic databases were searched: PubMed, EMBASE and Cochrane. Studies comparing outcomes in patients with the use of TAFT (TAFT+) and patients without the use of TAFT (TAFT-) were scrutinized. The quality of included studies was evaluated with the Newcastle-Ottawa scale score. Statistical heterogeneity was assessed using the I2 value. A fixed or random-effect model was applied. RESULTS: Four retrospective controlled studies involving 455 patients were included. The pooled estimates showed that the use of TAFT significantly increased the risk of stricture, with a risk ratio (RR) of 1.83 (95% CI 1.30-2.58; P = 0.0005). The meta-analyses of other postoperative complications did not show significant differences between TAFT+ and TAFT- group, with a RR of 1.65 (95% CI 0.93-2.93; P = 0.09) for anastomotic leakage, 0.91 (95% CI 0.34-2.44; P = 0.85) for sepsis, 1.89 (95% CI 0.22-16.20; P = 0.56) for tracheomalacia, 0.50 (95% CI 0.13-1.93; P = 0.31) for gastroesophageal reflux, 1.29 (95% CI 0.28-5.92; P = 0.74) for wound infection, and 0.97 (95% CI 0.03-36.75; p = 0.99) for pneumonia. CONCLUSIONS: This study demonstrates that the use of TAFT in patients with EA significantly increases the risk of stricture. However, TAFT is not associated with other complications, including anastomotic leakage, sepsis, tracheomalacia, gastroesophageal reflux, wound infection and pneumonia.

Cationic Gemini Surfactants with a Bipyridyl Spacer as Corrosion Inhibitors for Carbon Steel.

In this work, cationic Gemini surfactants with different alkyl chain lengths (n = 8, 10, and 12) and a bipyridyl spacer were synthesized and tested as corrosion inhibitors for carbon steel in 1 M HCl solution. The corrosion inhibition efficiency was determined by weight loss measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy. Results showed that such three inhibitors could effectively inhibit the corrosion of carbon steel in 1 M HCl solution, especially at their low concentrations, while the carbon chain length of Geminis used played a negligible role in the inhibition efficiency. Scanning electron microscopy/energy dispersive X-ray analysis observations demonstrated the formation of a protective inhibitor layer on the carbon steel surface. Additionally, the adsorption of the inhibitor molecules on the carbon steel surface was found to obey the Langmuir isotherm.

[Characterization of D-amino acid oxidase and its mutants from Arthrobacter protophormiae].

OBJECTIVE: To characterize D-amino acid oxidase from Arthrobacter protophormiae (DSM 20168). METHODS: Genes apdaao-1 and apdaao-2 from A. protophormiae (DSM 15035 & 20168) were cloned by PCR; expression vectors were constructed and expressed in E. coli BL21 (DE3). The mutant was constructed by site-directed mutagenesis using plasmid pET-ApDAAO-2 as the template. After Ni-NTA column chromatography purification, the protein was characterized. RESULTS: Protein ApDAAO-1, ApDAAO-2 and 4 mutants were expressed and purified successfully. The apparent molecular masses of all purified proteins were about 36 kDa by SDS-PAGE. The optimum temperature of ApDAAO-2 and 4 mutants was 30 degrees C similar to ApDAAO-1. ApDAAO-2 and its mutants exhibited much broader optimal pH than ApDAAO-1, and they revealed broad substrate specificity and high specificity to D-Met (100%) except T256K, which showed the substrate preference for D-Phe (108%). For substrates D-Met and D-Phe, the second-order rate constants k(cat)/Km of ApDAAO-2 and 4 mutants were several-fold higher than ApDAAO-1 and pKDAAO, respectively. CONCLUSION: Comparing with ApDAAO-1 and pKDAAO, ApDAAO-2 and its mutants had much broader substrate specificity and higher catalytic efficiency, which suggested that they might have much higher commercial value.