Nanofiber scaffolds of polyvinyl alcohol, silk fibroin from
cocoons, and silver nanoparticles were developed as a substrate for MG-63 growth. The fiber morphology, mechanical properties, thermal ...degradation, chemical composition, and water contact angle were investigated. In vitro tests were performed by the cell viability MTS test of MG-63 cells on electrospun PVA scaffolds, mineralization was analyzed by alizarin red, and the alkaline phosphatase (ALP) assay was evaluated. At higher PVA concentrations, Young's modulus (E) increased. The addition of fibroin and silver nanoparticles improved the thermal stability of PVA scaffolds. FTIR spectra indicated characteristic absorption peaks related to the chemical structures of PVA, fibroin, and Ag-NPs, demonstrating good interactions between them. The contact angle of the PVA scaffolds decreased with the incorporation of fibroin and showed hydrophilic characteristics. In all concentrations, MG-63 cells on PVA/fibroin/Ag-NPs scaffolds had higher cell viability than PVA pristine. On day ten of culture, PVA18/SF/Ag-NPs showed the highest mineralization, observed by the alizarin red test. PVA10/SF/Ag-NPs presented the highest alkaline phosphatase activity after an incubation time of 37 h. The achievements indicate the potential of the nanofibers of PVA18/SF/Ag-NPs as a possible substitute for bone tissue engineering (BTE).
Oral examinations are not consistently included in third-year medical student clerkships. When included, they are often unstructured, leaving room for variations in difficulty or scoring. Previous ...research has demonstrated differences in clinical grade achievement, with underrepresented in medicine students receiving significantly lower grades than White students.
We designed a structured oral examination for third-year medical students on the surgery clerkship. Students completed 2 oral examination scenarios and were evaluated on their ability to complete a history and diagnostic workup, interpret laboratory and imaging results, and devise a treatment plan. Scores from our examination were compared to previous, unstructured oral examination scores and to student demographics. Students and faculty were surveyed regarding their experience.
Third-year medical students demonstrated strong knowledge of multiple surgical diseases. The greatest number of errors occurred in treatment planning (P < .001). Third-year medical students receiving honors clerkship grades achieved higher percentages of correct items on their oral examination. (94.8% vs 90.4%) (P = .02). Evaluation of prior unstructured oral examinations found underrepresented in medicine students received lower scores than White students (P = .04). After implementation of our structured examination, no difference was seen between the scores of underrepresented in medicine and White students (P = .99).
We implemented a standardized oral examination for third-year medical students on the surgery clerkship with student and faculty satisfaction and demonstrated the ability to determine domains of knowledge weakness. The application of our structured oral examination helped to address nonspecific grading practices and eliminate oral examination grade differences between underrepresented in medicine and White students.
The preoperative period is an important target for interventions (eg Surgical Prehabilitation and Readiness SPAR) that can improve postoperative outcomes for older patients with comorbidities.
To ...determine whether a preoperative multidisciplinary prehabilitation program (SPAR) reduces postoperative 30-day mortality and the need for non-home discharge in high-risk surgical patients, surgical patients enrolled in a prehabilitation program targeting physical activity, pulmonary function, nutrition, and mindfulness were compared with historical control patients from 1 institution's American College of Surgeons (ACS) NSQIP database. SPAR patients were propensity score-matched 1:3 to pre-SPAR NSQIP patients, and their outcomes were compared. The ACS NSQIP Surgical Risk Calculator was used to compare observed-to-expected ratios for postoperative outcomes.
A total of 246 patients were enrolled in SPAR. A 6-month compliance audit revealed that overall patient adherence to the SPAR program was 89%. At the time of analysis, 118 SPAR patients underwent surgery with 30 days of follow-up. Compared with pre-SPAR NSQIP patients (n = 4,028), SPAR patients were significantly older with worse functional status and more comorbidities. Compared with propensity score-matched pre-SPAR NSQIP patients, SPAR patients had significantly decreased 30-day mortality (0% vs 4.1%, p = 0.036) and decreased need for discharge to postacute care facilities (6.5% vs 15.9%, p = 0.014). Similarly, SPAR patients exhibited decreased observed 30-day mortality (observed-to-expected ratio 0.41) and need for discharge to a facility (observed-to-expected ratio 0.56) compared with their expected outcomes using the ACS NSQIP Surgical Risk Calculator.
The SPAR program is safe and feasible and may reduce postoperative mortality and the need for discharge to postacute care facilities in high-risk surgical patients.
Developed countries have shown a time trend towards a younger age at menarche (AAM), which is associated with increased risk of later obesity and non-communicable diseases. This study aimed to assess ...whether a time trend in AAM is associated with disease risk in Mexican women (
= 30,826), using data from the Mexican National Health Survey (2000). Linear and log binomial regression was used for nutritional and disease outcomes, while Welch⁻ANOVA was used to test for a time trend. AAM (in years) decreased over time (
< 0.001), with a maximal difference of 0.99 years between the 1920s (13.6 years) and 1980s (12.6 years ). AAM was negatively associated with weight (β = -1.01 kg; 95% CI -1.006, -1.004) and body mass index (BMI) (β = -1.01 kg/m²; -1.007, -1.006), and positively with height (β = 0.18 cm; 0.112, 0.231). AAM was associated with diabetes (RR = 0.95; 0.93, 0.98) and hypercholesterolemia (RR = 0.93; 0.90, 0.95), but not with hypertension, breast cancer or arthritis. In Mexico, AAM decreased significantly during the 20th century. AAM was inversely associated with adult weight and BMI, and positively with height. Women with a later AAM had a lower risk of diabetes and hypercholesterolemia.
Lactobacilli, the predominant micro-organisms of the vaginal microbiota, play a major role in the maintenance of a healthy urogenital tract by preventing the colonization of pathogenic bacteria. The ...aim of the present study was to assess the ability of four vaginal Lactobacillus strains, previously selected for their probiotic features, to block in vitro the adherence of three human urogenital pathogens to vaginal epithelial cells (VEC). Three types of assays were performed in order to determine the inhibitory effect of lactobacilli on adhesion of urogenital pathogens to VEC: blockage by exclusion (lactobacilli and VEC followed by pathogens), competition (lactobacilli, VEC and pathogens together) and displacement (pathogens and VEC followed by the addition of lactobacilli). Bacterial adhesion to VEC was quantified by microscopy (x1000) after Gram's stain. All the strains were able to inhibit by exclusion and competition the adhesion of Staphylococcus aureus to VEC but none was able to decrease the attachment of Escherichia coli by neither of the mechanisms assayed. Only Lactobacillus acidophillus CRL 1259 and Lactobacillus paracasei CRL 1289 inhibited the attachment of Group B streptococci (GBS) to VEC by exclusion and competition respectively. Lactobacillus of vaginal origin were able to inhibit the attachment of genitouropathogenic Staph. aureus and GBS to the vaginal epithelium. The results support the probiotic potential of these Lactobacillus strains as anti-infective agents in the vagina and encourage further studies about their capacity to prevent and manage urogenital tract infections in females.
•Analysis for HDS process at three different scales.•Study of the validity of idealities as flow plug in TBR for HDS process.•The lack of exchange information between two scales leads to important ...deviations.•Effectiveness factor in insolated catalysts differ from embedded particles.•External mass resistances for catalyst leads to field jumps at the interface.
For the hydrotreatment process of petroleum cuts, there is a great diversity and level of Trickle Bed Reactors (TBR) models, in which it is very common to use important simplifications, such as the consideration of plug flow; these simplifications restrict the analysis of the multiphysics and multiscale nature of the phenomena that take place in such systems. The analysis of the phenomena that take place at different scales in the TBRs is very scarce; moreover, the qualitative and quantitative determination of the information that passes from one to another scale and its influence on the mass transport nature in these systems is even more difficult to find. With the purpose of analyzing the multiphysic and multiscale nature of a reactor for an HDS process, three Computational Fluid Dynamics (CFD) models were studied at three different scales, corresponding to: (i) Heterogeneous micropores model (HMM) for a particle with explicit representation of the internal surface microstructure of the catalyst, (ii) Pseudohomogeneous catalyst particle model (PCM), and (iii) Reactor scale model (RSM). The objective sought is to establish the validity of some of the assumptions commonly made in the simulation of these types of reactors and develop an analysis to determine the importance of establishing bridges of information between the phenomena that take place at different scales. The results show that despite the small dimensions of the reactor, the plug flow assumptions might not be valid, due to the presence of strong radial gradients. It was also determined that the models that do not take into account the communication between scales (catalysts to reactor scale) differ substantially from those that do, which can be verified by the differences found for the effectiveness factors, of around 35%.
For the assessment of existing slab-between-girder bridges, the shear capacity and failure mode are under discussion. In particular, preliminary assessment calculations showed that the critical ...failure mode of the girders is shear-tension. In this paper, four girders taken from a demolished bridge that were tested in the lab are analyzed according to existing codes. The comparison between the experiments and the analysis shows that the Dutch RBK provisions are conservative and the ACI 318-19 provisions result in good predictions of the shear capacity at inclined cracking and at ultimate. These observations are then combined into recommendations for the assessment of prestressed concrete girders in existing slab-between-girder bridges for shear cracking and the ultimate shear capacity. Keywords: bridge assessment; concrete bridges; flexure-shear; large-scale testing; prestressed concrete; shear; shear-compression; shear-tension.
Molecular relaxations of chitosan films have been investigated in the wide frequency range of 0.1 to 3 × 10
9
Hz from −10 °C to 110 °C using dielectric spectroscopy. For the first time, two ...high-frequency relaxation processes (in the range 10
8
to 3 × 10
9
Hz) are reported in addition to the low frequency relaxations α and β. These two relaxation processes are related to the vibrations of OH and NH
2
/NH
3
+
, respectively. The high-frequency relaxations exhibit Arrhenius-type dependencies in the temperature range 10 °C to 54 °C with negative activation energy; this observation is traceable to hydrogen bonding reorientation. At temperatures above the glass transition temperature (54 °C), the activation energy changes from negative to positive values due to breaking of hydrogen bonding and water loss. Upon cooling in a sealed environment, the activation energies of two relaxation processes are nearly zero. FTIR and XRD analyses reveal associated structural changes upon heating and cooling. These two new high-frequency relaxation processes can be attributed to the interaction of bound water with OH and NH
2
/NH
3
+
, respectively. A plausible scenario for these high-frequency relaxations is discussed in light of impedance spectroscopy, TGA, FTIR and XRD measurements.
Temperature-dependence relaxation time of OH side groups
versus
1/
T
for chitosan films in the heating and cooling process. The solid lines represent Arrhenius-type dependence fitting. Schematic of proposed molecular interactions.
Pancreaticoduodenectomy (PD) has a high rate of readmission, and racial disparities in care could be an important contributor.
Patients undergoing PD were prospectively followed, and their ...complications graded using the Modified Accordion Grading System (MAGS). Patient factors and perioperative outcomes for patients with and without postoperative readmission were compared in univariate and multivariate analysis by severity.
837 patients underwent PD, the overall 90-day readmission rate was 27.5%. Non-white race was independently associated with readmission (OR 1.83, p = 0.007). 51.3% of readmissions were for non-severe complications (MAGS <3). Non-white race was independently associated with MAGS non-severe readmission (OR 2.13, p = 0.006), but not MAGS severe readmission.
Non-white patients are more likely to be readmitted, particularly for non-severe complications. Follow up protocols should be tailored to address race disparities in the rates of readmission as readmission for less severe complications could potentially be avoidable.
•Pancreaticoduodenectomy (PD) is a complex procedure with a high readmission rate.•Non-white race is an important risk factor for readmission after PD.•Non-white patients are readmitted disproportionately for non-severe complications.•Follow up protocols should be tailored to address race disparities in readmissions.
Due to the COVID-19 pandemic, the recruitment cycle for the 2021 Match was performed virtually. This Association for Surgical Education (ASE)-sponsored survey set out to study applicants’ ability to ...assess the factors contributing to fit through video interviews.
An IRB-approved, online, anonymous survey was distributed to surgical applicants at a single academic institution and through the ASE clerkship director distribution list between the rank order list certification deadline and Match Day. Applicants used 5-point Likert-type scales to rate factors for importance to fit and their ease of assessment through video interviewing. A variety of recruitment activities were also rated by applicants for their perceived helpfulness in assessment of fit.
One hundred and eighty-three applicants responded to the survey. The three most important factors for applicant fit were how much the program cared, how satisfied residents seem with their program, and how well residents get along. Resident rapport, diversity of the patient population, and quality of the facilities were hardest to assess through video interviews. In general, diversity-related factors were more important to female and non-White applicants, but not more difficult to assess. Interview day and resident-only virtual panels were the most helpful recruitment activities, while virtual campus tours, faculty-only panels, and a program's social media were the least helpful.
This study provides valuable insight into the limitations of virtual recruitment for surgical applicants’ perception of fit. These findings and the recommendations herein should be taken into consideration by residency program leadership to ensure successful recruitment of diverse residency classes.
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