Work function modification of PEDOT:PSS by mixing with barium acetylacetonate

Poly(3,4-ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS) is often used as a hole injection and extractor for various organic electronic devices. This study investigated whether it is possible to n-dope PEDOT:PSS with barium acetylacetonate (Ba(acac)₂) to change its work function so that to be more suitable for electron injection and extraction. Molecular dynamics simulations suggested that barium cations can interact with the aromatic rings of PEDOT and the negatively charged sulfonate in PSS. At high doping concentration, we found that PEDOT became dedoped and precipitated resulting in a clear solution after filtration. The absence of the absorption peak of PEDOT at 263 nm indicates the removal of PEDOT after filtration. The shift in O 1s to a lower binding energy as seen in X-ray photoelectron spectroscopy suggested that the polystyrene sulfonic acids are being ionized to form barium polystyrene sulfonate (Ba–PSS). By spin-coating the solution on top of indium tin oxide, the work function can be adjusted to as low as 3.6 eV. The ability of such a mixture to inject and extract electrons is demonstrated using 2,7-bis(diphenylphosphoryl)-9,9′-spirobifluorene as an electron transporting layer. We attributed the lowering of the work function as the result of the formation of an interfacial dipole as large as 1.37 eV at the ITO/Ba–PSS interface.

Modification of poly(3,4-ethylenedioxythiophene)polystyrene sulfonate as electron injection layer.     

In vitro evaluation of novel low-pressure spark plasma sintered HA–BG composite scaffolds for bone tissue engineering

The low-pressure spark plasma sintering (SPS) technique is adopted to fabricate hydroxyapatite–bioglass (HA–BG) scaffolds while maintaining the physical properties of both components, including their bulk and relative density and hardness. However, prior to their orthopaedic and dental applications, these scaffolds must be validated via pre-clinical assessments. In the present study, scaffolds with different ratios of HA : BG, namely, 100 : 0 (HB 0 S), 90 : 10 (HB 10 S), 80 : 20 (HB 20 S) and 70 : 30 (HB 30 S) were fabricated. These scaffolds were characterized by investigating their physicochemical properties (X-ray diffraction (XRD) and surface wettability), bioactivity in a simulated body fluid (SBF) (field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR) and calcium dissolution), antimicrobial properties, biocompatibility and osteoinduction of human bone marrow-derived mesenchymal stromal cells (hBMSCs) and human monocyte immune cell response. The XRD and surface wettability results confirmed no formation of undesirable phases and the enhanced surface hydrophilicity of the scaffolds, respectively. The bioactivity in SBF indicated the formation of bone-like apatite on the surface of the scaffolds, corresponding to an increase in BG%, which was confirmed through FTIR spectra and the increasing trend of calcium release in SBF. The scaffolds showed inhibition properties against Staphylococcus aureus and Staphylococcus epidermidis. The scanning electron microscopy (SEM) micrographs and Alamar Blue proliferation assay indicated the good attachment and significant proliferation, respectively, of hBMSCs on the scaffolds. Alizarin Red S staining confirmed that the scaffolds supported the mineralisation of hBMSCs. The osteogenic protein secretion (bone morphogenetic protein-2 (BMP2), type-I collagen (COL1) and osterix (OSX)) was significant on the HB 30 S-seeded hBMSCs when compared with that of HB 0 S. The monocyte migration was significantly halted in response to HA–BG-conditioned media when compared with the positive control (monocyte chemoattractant protein-1: MCP-1). In conclusion, the HB 30 S composite scaffold has a greater potential to substitute bone grafts in orthopaedic and dental applications.

HB 30 S composite scaffold inhibits Staphylococcus spp., supports the biocompatibility and osteogenic differentiation of hBMSCs and resists monocyte migration.     

Interest and attitudes of patients,cancer physicians,medical students and cancer researchers towards a spectrum of genetic tests relevant to breast cancer patients

The perspectives of patients and healthcare professionals towards breast cancer genetic tests that are becoming increasingly available is unexplored in Asians. We surveyed the interest and attitudes of 200 breast cancer patients, 67 cancer physicians, 485 medical students and cancer researchers towards three genetic tests, BRCA1/2 mutation, CYP2D6 genotype and Oncotype DX testing, using hypothetical scenarios. Approximately 60% of patients expressed initial interest in each genetic test, although the majority reversed their decisions once test limitations were conveyed, with <15% maintaining interest in each test. Cancer physicians were most likely to recommend BRCA1/2 mutation testing (73%) and least likely to recommend CYP2D6 genotyping (12%), while patients were more likely to choose Oncotype DX testing (28%) over CYP2D6 (21%) and BRCA1/2 testing (15%). Cost concerns, low educational level and lack of prior awareness of genetic testing were the main barriers against breast cancer genetic testing among Asian patients.     

Laparoscopic Silastic Ring Mini-gastric Bypass: a Single Centre Experience

Background

Laparoscopic mini-gastric bypass (MGBP) represents a simpler alternative to Roux-en-Y gastric bypass. The placement of a silastic ring (SR) may enhance excess weight loss and minimize weight regain. This study reports on the results of a consecutive cohort of patients undergoing SR-MGBP in a single centre.

Methods

Short- and medium-term outcomes of 156 consecutive patients undergoing surgery between August 2005 and January 2008 were analysed. Weight loss, comorbidity resolution and morbidity/mortality were assessed.

Results

A total of 156 patients (78% female, 22% male) with a mean (range) age of 44 years (18–63), pre-operative weight of 129 kg (83–197) and body mass index of 46 kg/m² (35–64) underwent surgery. Eighty-seven percent had pre-operative comorbidities, and median (range) follow-up was 35 months (6–72). Mean (SD) % excess weight loss (EWL) at 6, 12, 24, 36 and 60 months was 74.6 (19.5), 93.4 (21.1), 98.8 (27.6), 93.5 (20.1) and 89 (16.1) respectively. Thirty-seven percent had complete resolution of comorbidities and 67.3% required vitamin/mineral supplementation. Overall, 10.3% patients suffered early complications, of which 7.7% were minor and 2.6% were major. A total of 45.5% patients suffered late complications, of which 34.6% were minor and 10.9% were major. Food intolerance/vomiting, bile reflux and stomal ulcer were seen in 18.6, 10.3 and 7.7% of patients, respectively. Surgical re-intervention was required in 12.8% of patients. There were no deaths.

Conclusions

Whilst SR-MGBP achieves excellent EWL with low mortality, there is a high incidence of food intolerance/vomiting likely related to the silastic ring. The majority of complications were managed with pharmacological and endoscopic intervention, although 13% required reoperation within 5 years.     

Surgical safety checklist: implementation in an ambulatory surgical facility

Purpose

In 2007, the World Health Organization created a Surgical Safety Checklist (SSC) that encompassed a simple set of surgical safety standards. The threefold purpose of this study was to add ambulatory-specific items to the SSC, to introduce the items into an ambulatory surgical facility, and to determine if patient outcomes regarding postoperative pain and nausea/vomiting improved following implementation. In addition, safety attitudes, antibiotic timing, regional anesthesia/nerve blocks, preemptive pain medications, prophylactic antiemetics, length of stay, and hospital admission were also assessed.

Methods

After Research Ethics Board approval, staff complete a Safety Attitudes Questionnaire. Seven items were added to the SSC. Data were then collected on 180 surgical cases before SSC implementation and 195 cases following implementation. Compliance with each section of the SSC was assessed.

Results

On postoperative day one, the median (97.5% confidence interval [CI]) difference between pre- and post-implementation pain scores was 0.5 (97.5% CI, 0 to 1; P = 0.13), and the median difference in the rate of post-discharge nausea/vomiting was ?8.4% (97.5% CI, ?17.9 to 1.1; P = 0.06). There was no improvement in safety attitudes or any of the secondary outcomes, with the exception of the use of preemptive pain medications. Compliance with the three sections of the checklist, i.e., BRIEFING, TIME OUT, and DEBRIEFING was 99.49%, 97.95%, and 96.92%, respectively. There was low compliance in verbalization of the added “ambulatory-specific items”.

Conclusion

Potential reasons for lack of uptake and integration include poor “user” buy-in, an overly lengthy checklist, and lack of prioritization of ambulatory-specific items. A shortened SSC was developed based on the results of this study. This trial was registered at ClinicalTrials.gov ID: NCT00934310.     

Major complications related to epidural analgesia in children: a 15-year audit of 3,152 epidurals

Background

Complications associated with epidural analgesia in children have a reported incidence of 40-90 in 10,000 epidurals. We sought to determine the incidence of major complications with the use of continuous epidural analgesia that occurred in our centre over the past 15 years and to describe the nature of these complications.

Methods

The Acute Pain Service database at a tertiary care academic pediatric hospital was reviewed retrospectively over a 15-year period. Data were categorized according to patient age (neonate, infant, child one through eight years, and child > eight years), mode of insertion of the epidural (caudal, transsacral, lumbar, thoracic), complication type, and complication severity.

Results

Over the 15-year period, 3,152 epidurals were performed. The use of caudal-thoracic epidurals in neonates and infants has increased since 2007. Twenty-four major complications were identified (incidence, 7.6 in 1,000 epidurals). The rate of complications in neonates was 4.2% compared with 1.4% in infants, 0.5% in children aged one through eight years, and 0.8% in children over eight years of age. The two most common complications were local skin infection and drug error.

Conclusions

Our incidence of major complications and our finding that complications were more common in neonates and infants are both consistent with previously published data. The two most common types of complications are potentially preventable.     

The difficult airway with recommendations for management – Part 1 – Difficult tracheal intubation encountered in an unconscious/induced patient

Background

Previously active in the mid-1990s, the Canadian Airway Focus Group (CAFG) studied the unanticipated difficult airway and made recommendations on management in a 1998 publication. The CAFG has since reconvened to examine more recent scientific literature on airway management. The Focus Group’s mandate for this article was to arrive at updated practice recommendations for management of the unconscious/induced patient in whom difficult or failed tracheal intubation is encountered.

Methods

Nineteen clinicians with backgrounds in anesthesia, emergency medicine, and intensive care joined this iteration of the CAFG. Each member was assigned topics and conducted reviews of Medline, EMBASE, and Cochrane databases. Results were presented and discussed during multiple teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made together with assigned levels of evidence modelled after previously published criteria.

Conclusions

The clinician must be aware of the potential for harm to the patient that can occur with multiple attempts at tracheal intubation. This likelihood can be minimized by moving early from an unsuccessful primary intubation technique to an alternative “Plan B” technique if oxygenation by face mask or ventilation using a supraglottic device is non-problematic. Irrespective of the technique(s) used, failure to achieve successful tracheal intubation in a maximum of three attempts defines failed tracheal intubation and signals the need to engage an exit strategy. Failure to oxygenate by face mask or supraglottic device ventilation occurring in conjunction with failed tracheal intubation defines a failed oxygenation, “cannot intubate, cannot oxygenate” situation. Cricothyrotomy must then be undertaken without delay, although if not already tried, an expedited and concurrent attempt can be made to place a supraglottic device.