A Comparison of Different Textured and Non-Textured Anti-Reflective Coatings for Planar Monolithic Silicon-Perovskite Tandem Solar Cells.

Multijunction solar cells offer a route to exceed the Shockley-Queisser limit for single-junction devices. In a few short years, silicon-perovskite tandems have significantly passed the efficiency of the best silicon single-junction cells. For scalable solution processing of silicon-perovskite tandem devices, with the avoidance of vacuum processing steps, a flat silicon sub-cell is normally required. This results in a flat top surface that can lead to higher optical reflection losses than conformal deposition on textured silicon bottom cells. To overcome this, textured anti-reflective coatings (ARCs) can be used on top of the finished cell, with textured polydimethylsiloxane (PDMS), a promising candidate. In this work, we vary the texture geometry and film thickness of PDMS anti-reflective foils to understand the effect of these parameters on reflectance of the foil. The best film is selected, and anti-reflective performance is compared with two common planar ARCs-lithium fluoride (LiF) and magnesium fluoride (MgF2) showing considerable reduction in reflectance for a non-textured silicon-perovskite tandem cell. The application of a PDMS film is shown to give a 3-5% increase in integrated J SC in each sub-cell of a silicon-perovskite tandem structure.

Bioengineering horizon scan 2020.

Horizon scanning is intended to identify the opportunities and threats associated with technological, regulatory and social change. In 2017 some of the present authors conducted a horizon scan for bioengineering (Wintle et al., 2017). Here we report the results of a new horizon scan that is based on inputs from a larger and more international group of 38 participants. The final list of 20 issues includes topics spanning from the political (the regulation of genomic data, increased philanthropic funding and malicious uses of neurochemicals) to the environmental (crops for changing climates and agricultural gene drives). The early identification of such issues is relevant to researchers, policy-makers and the wider public.

What Factors Necessitate Removal of Retained Ballistic Fragments in the Head and Neck?

PURPOSE: The purpose of this study was to estimate the frequency of retained ballistic fragment (RBF) removal and to identify factors associated with an increased risk for RBF removal. To date, there are no studies focused on identifying factors associated with removal of RBFs localized to the maxillofacial region. MATERIALS AND METHODS: Using a retrospective cohort study design, the authors enrolled a sample composed of patients with RBFs localized to the maxillofacial region. The predictor variables included bullet size, location, involvement of bone, involvement of sinus, antibiotics, multiple antibiotics, and multiple locations. The primary outcome variable was RBF retrieval. The secondary outcome variables were timing of operative retrieval, fragment site infection, and migration of RBF. Appropriate uni- and bivariate statistics were computed and logistic regression modeling was used. RESULTS: The sample was composed of 20 patients (mean age, 30 yr; 80% male) and 55% (11 patients) required or desired object removal overall. The number of projectiles ranged from 1 to 19 (total, 48) in the 20 patients. The logistic model identified larger size, final location of bone, final location of soft tissue, and final location of sinus as having a higher probability of removal that was statistically significant (P < .05); however, size was the only variable with a substantial odds ratio (OR; 1.96; P < .05). There was no evidence of migration and a low rate (2.3%) of infection was noted at subsequent follow-up radiography and clinical examination. CONCLUSION: Size was the only statistically significant predictor variable with a substantial OR (1.96; 95% confidence interval, 1.31-3.40; P < .05). There was a low risk of infection even when considering oral pharyngeal contamination and low risk of migration. Further studies could focus on prudent antibiotic use and larger patient populations.

A transatlantic perspective on 20 emerging issues in biological engineering.

Advances in biological engineering are likely to have substantial impacts on global society. To explore these potential impacts we ran a horizon scanning exercise to capture a range of perspectives on the opportunities and risks presented by biological engineering. We first identified 70 potential issues, and then used an iterative process to prioritise 20 issues that we considered to be emerging, to have potential global impact, and to be relatively unknown outside the field of biological engineering. The issues identified may be of interest to researchers, businesses and policy makers in sectors such as health, energy, agriculture and the environment.

Students' perceptions of the Script Concordance Test and its impact on their learning behavior: a mixed methods study.

The Script Concordance Test (SCT) is increasingly used in postgraduate and undergraduate education as a method of summative clinical assessment. It has been shown to have high validity and reliability but there is little evidence of its use in veterinary education as assessment for learning. This study investigates some students' perceptions of the SCT and its effects on their approaches to learning. Final-year undergraduates of the School of Veterinary Medicine and Science (SVMS) at the University of Nottingham participated in a mixed-methods study after completing three formative SCT assessments. A qualitative, thematic analysis was produced from transcripts of three focus group discussions. The quantitative study was a survey based on the analyses of the qualitative study. Out of 50 students who registered for the study, 18 participated in the focus groups and 28 completed the survey. Clinical experience was regarded as the most useful source of information for answering the SCT. The students also indicated that recall of facts was perceived as useful for multiple-choice questions but least useful for the SCT. Themes identified in the qualitative study related to reliability, acceptability, educational impact, and validity of the SCT. The evidence from this study shows that the SCT has high face validity among veterinary students. They reported that it encouraged them to reflect upon their clinical experience, to participate in discussions of case material, and to adopt a deeper approach to clinical learning. These findings strongly suggest that the SCT is potentially a valuable method for assessing clinical reasoning and enhancing student learning.

The educational impact of assessment: a comparison of DOPS and MCQs.

AIM: To evaluate the impact of two different assessment formats on the approaches to learning of final year veterinary students. The relationship between approach to learning and examination performance was also investigated. METHOD: An 18-item version of the Study Process Questionnaire (SPQ) was sent to 87 final year students. Each student responded to the questionnaire with regards to DOPS (Direct Observation of Procedural Skills) and a Multiple Choice Examination (MCQ). Semi-structured interviews were conducted with 16 of the respondents to gain a deeper insight into the students' perception of assessment. RESULTS: Students' adopted a deeper approach to learning for DOPS and a more surface approach with MCQs. There was a positive correlation between an achieving approach to learning and examination performance. Analysis of the qualitative data revealed that deep, surface and achieving approaches were reported by the students and seven major influences on their approaches to learning were identified: motivation, purpose, consequence, acceptability, feedback, time pressure and the individual difference of the students. CONCLUSIONS: The format of DOPS has a positive influence on approaches to learning. There is a conflict for students between preparing for final examinations and preparing for clinical practice.

Analysing the hidden curriculum: use of a cultural web.

CONTEXT: Major influences on learning about medical professionalism come from the hidden curriculum. These influences can contribute positively or negatively towards the professional enculturation of clinical students. The fact that there is no validated method for identifying the components of the hidden curriculum poses problems for educators considering professionalism. The aim of this study was to analyse whether a cultural web, adapted from a business context, might assist in the identification of elements of the hidden curriculum at a UK veterinary school. METHODS: A qualitative approach was used. Seven focus groups consisting of three staff groups and four student groups were organised. Questioning was framed using the cultural web, which is a model used by business owners to assess their environment and consider how it affects their employees and customers. The focus group discussions were recorded, transcribed and analysed thematically using a combination of a priori and emergent themes. RESULTS: The cultural web identified elements of the hidden curriculum for both students and staff. These included: core assumptions; routines; rituals; control systems; organisational factors; power structures, and symbols. Discussions occurred about how and where these issues may affect students' professional identity development. CONCLUSIONS: The cultural web framework functioned well to help participants identify elements of the hidden curriculum. These aspects aligned broadly with previously described factors such as role models and institutional slang. The influence of these issues on a student's development of a professional identity requires discussion amongst faculty staff, and could be used to develop learning opportunities for students. The framework is promising for the analysis of the hidden curriculum and could be developed as an instrument for implementation in other clinical teaching environments.

Incidence of elevation of cardiac troponin I prior to and following routine general anaesthesia in dogs.

OBJECTIVE: To estimate the incidence of raised cTnI after general anaesthesia in dogs and to explore major risk factors influencing this. STUDY DESIGN: Prospective clinical study. Animals A total of 107 (ASA physical status 1-2) dogs, 63% male and 37% female, median age 5 years (range 0.3-13.4), median weight 24.4 kg (range 4.2-66.5 kg) undergoing anaesthesia for clinical purposes. METHODS: Venous blood samples were taken within 24 hours prior to induction and 24 hours after the termination of anaesthesia. Serum concentrations of cardiac troponin I were measured using a chemiluminescent enzyme immunometric assay with a lower level of detection of 0.20 ng mL(-1) (below this level <0.20 ng mL(-1)). Continuous data were assessed graphically for normality and paired and unpaired data compared with the Wilcoxon signed ranks and Mann-Whitney U-tests respectively. Categorical data were compared with the Chi squared or Fisher's exact test as appropriate (p < 0.05). RESULTS: Of the 107 dogs recruited, 100 had pre- and post-anaesthetic cTnI measured. The median pre-anaesthesia cTnI was '<0.20' ng mL(-1) (range '<0.20'-0.43 ng mL(-1)) and the median increase from pre-anaesthesia level was 0.00 ng mL(-1) (range -0.12 to 0.61 ng mL(-1)). Fourteen dogs had increased cTnI after anaesthesia relative to pre-anaesthesia (14%, 95% CI 7.2-20.8%, range of increase 0.03-0.61 ng mL(-1)). Six animals had cTnI levels that decreased (range 0.02-0.12 ng mL(-1)). Older dogs were more likely to have increased cTnI prior to anaesthesia (OR = 5.32, 95% CI 1.35-21.0, p = 0.007) and dogs 8 years and over were 3.6 times as likely to have an increased cTnI after anaesthesia (95% CI 1.1-12.4, p = 0.028). CONCLUSION AND CLINICAL RELEVANCE: Increased cTnI after anaesthesia relative to pre-anaesthesia levels was observed in a number of apparently healthy dogs undergoing routine anaesthesia.

Positive frequency shifts observed upon adsorbing micron-sized solid objects to a quartz crystal microbalance from the liquid phase.

By specifically binding derivatized colloidal particles and physisorbing nonderivatized particles to the surface of a quartz crystal microbalance (QCM), we have observed positive shifts of frequency, Deltaf, in contrast to the negative frequency shifts typically found in adsorption experiments. Evidently, the Sauerbrey relation does not apply to this situation. A comparison of frequencies shifts and bandwidths on different overtones reveals a coupled resonance: at low overtones, Deltaf is negative, whereas it is positive at high overtones, with maximal resonance bandwidth observed at the crossover point. As predicted by the Dybwad model, the spheres bound to the surface form resonating systems on their own. A composite resonator is formed, consisting of a large crystal with resonance frequency omega and the adsorbed spheres with resonance frequency omega(S). In the case in which the resonance frequency of the small spheres (firmly attached to crystal), omega(S), is higher than the resonance frequency of the crystal, omega, Deltaf of the composite system is negative (leading to the Sauerbrey limit). In the opposite limit (that is, in the case of large adsorbed particles bound to the sensor surface via a sufficiently weak bridge) Deltaf is positive. Such a behavior is known from sphere-plate contacts in the dry state. Finite element calculation demonstrates that this phenomena is also plausible in liquid phase media, with Deltaf critically dependent on the strength of the sphere-plate contact. Operated in this mode, the QCM most likely probes the contact strength, rather than the mass of the particle.

The risk of death: the confidential enquiry into perioperative small animal fatalities.

OBJECTIVE: To estimate the risks of anaesthetic and sedation-related mortality in companion animals in the UK. (The Confidential Enquiry into Perioperative Small Animal Fatalities, CEPSAF). STUDY DESIGN: A prospective cohort study with nested case-control study. ANIMAL POPULATION: All small animals anaesthetized and sedated at participating centres between June 2002 and June 2004. METHODS: Patient outcomes at 48 hours (alive, dead and killed) were recorded. Anaesthetic and sedation-related death was defined as death where surgical or pre-existing medical causes did not solely cause death. Species-specific risks of anaesthetic-related death and 95% confidence intervals (95% CI) were calculated. Risks were also estimated in the sub-sets of dogs, cats and rabbits that were either healthy or sick (ASA 1-2 and 3-5, respectively). RESULTS: One hundred and seventeen veterinary practices participated in the study and 98 036 dogs, 79 178 cats and 8209 rabbits were anaesthetized and sedated. Overall risks of anaesthetic and sedation-related death in dogs were 0.17% (1 in 601, 95% CI 0.14-0.19%), in cats 0.24% (1 in 419, 95% CI 0.20-0.27%) and in rabbits 1.39% (1 in 72, 95% CI 1.14-1.64%) within 48 hours of the procedure. In healthy dogs, cats and rabbits, the risks were estimated to be 0.05% (1 in 1849, 95% CI 0.04-0.07%), 0.11%, (1 in 895, 95% CI 0.09-0.14%) and 0.73% (1 in 137, 95% CI 0.54-0.93%), respectively. In sick dogs, cats and rabbits, the risks were 1.33%, (1 in 75, 95% CI 1.07-1.60%), 1.40% (1 in 71, 95% CI 1.12-1.68%) and 7.37% (1 in 14, 95% CI 5.20-9.54%), respectively. Postoperative deaths accounted for 47% of deaths in dogs, 61% in cats and 64% in rabbits. Most other small animal species had higher mortality risks. CONCLUSIONS AND CLINICAL RELEVANCE: Small animal anaesthesia appears to be increasingly safe. Greater patient care in the postoperative period could reduce fatalities.

The isoflurane-sparing and clinical effects of a constant rate infusion of remifentanil in dogs.

OBJECTIVE: To evaluate the isoflurane-sparing and clinical effects of two constant rate infusions of remifentanil in healthy dogs undergoing orthopaedic surgery. STUDY DESIGN: Prospective, randomized clinical study. ANIMALS: Forty-one American Society of Anesthesiologists I-II client-owned dogs (age, 7 months-9 years; body mass 11-59 kg). METHODS: Dogs were randomly assigned to one of three groups and received either: intramuscular (IM) meperidine 2 mg kg(-1) every 2 hours throughout surgery (control group (C); n = 13); remifentanil infused intravenously (IV) at 0.1 microg kg(-1) minute(-1) (low remifentanil group (L); n = 14) or remifentanil infused at 0.25 microg kg(-1) minute(-1) IV (high remifentanil group (H); n = 14). Anaesthesia was induced with thiopental administered to effect and maintained using isoflurane in 100% oxygen. During controlled ventilation when the end-tidal CO(2) was maintained between 4.65 and 5.98 kPa [35-45 mmHg], the end-tidal isoflurane concentration (e'iso%), mean arterial blood pressure (MAP) and heart rate (HR) were measured every 5 minutes. Bradycardia (HR < 40 minute(-1) lasting >5 minutes) was corrected with 0.01 mg kg(-1) IV glycopyrrolate. Data were analysed using the Kruskal-Wallis test with a post-hoc Mann-Whitney U-test and Bonferroni correction. Statistical significance was accepted at < or = 0.05. Data are expressed as mean +/- standard deviation. RESULTS: The e'iso% was reduced in a dose-dependent manner by remifentanil. In C, e'iso% was 1.28 +/-0.13 and was significantly different from L (0.78 +/- 0.17, p < 0.001) and H (0.65 +/- 0.16, p < 0.001). HR was significantly different between groups (p < 0.001). There were no significant differences in MAP between groups. Glycopyrrolate was required in two, three and six dogs in the C, L and H groups respectively. CONCLUSIONS: Remifentanil infusion reduced the isoflurane concentration required for surgical anaesthesia during orthopaedic surgery. CLINICAL RELEVANCE: Remifentanil infusions may be a useful additive to isoflurane anaesthesia in healthy dogs.

An investigation of the bacterial contamination of small animal breathing systems during routine use.

OBJECTIVE: To investigate the need for sterilization of anaesthetic breathing systems to prevent cross-infection between animals due to the re-use of anaesthetic circuit tubing. STUDY DESIGN: Prospective microbiological study. METHODS: Bacteriology samples were taken from 37 sterile breathing systems, each used for 1 day, at two sampling sites (one proximal and one distal to the animal). The number of patient connections, cumulative anaesthesia time, culture results, number of colony-forming units and the number of different species were recorded. Secondly, four sterile breathing systems were used for 2 months under routine conditions and sampled every 2 weeks and the same parameters recorded. Finally, the inner surfaces of four sterile breathing systems were inoculated with a known load of canine oropharyngeal bacteria. Bacteriology samples were taken at 1 minute, 1 hour and 1 day post-deposition. The number of colonies identified was compared with the initial load. RESULTS: Only a very small number of micro-organisms were isolated and these were generally organisms of low pathogenic potential. The proximal site was found to be significantly more colonized than the distal site (p < 0.001). Neither longer daily connection time (p = 0.54), nor a higher number of connections (p = 0.81) increased the incidence of proximal site colonization. Over the 2-month study period, the bacterial population did not increase. There was no correlation between cultures isolated from successive samples taken from the same tubing. There was rapid loss of viability of the micro-organisms deliberately inoculated onto the tubing surface: the number of colonies isolated from the breathing system after 1 minute was significantly lower than in the inoculum (p = 0.042). CONCLUSIONS AND CLINICAL RELEVANCE: Sterile anaesthesia breathing systems were colonized by environmental micro-organisms of low pathogenicity. Although long-term survival of recognized pathogens in a dry environment is still possible, the use of a bacterial filter or a sterilized breathing system for routine veterinary anaesthesia cannot be supported by current evidence.

Solid-phase extraction and HPLC analysis of methylparaben and propylparaben in a concentrated antibiotic suspension.

An accurate and precise solid-phase extraction coupled with high performance liquid chromatography (SPE/HPLC) method developed for the quantification of antimicrobial preservatives (methylparaben and propylparaben) in oxytetracycline injectable suspension is described in this article. The SPE technique was necessary to quantify the preservatives since the high concentration of the drug and excipients was masking low levels of preservatives, making quantification difficult. This developed HPLC method was stability-indicating and found to be linear between 1.3 to 2.4 mg/mL for methylparaben and 0.15 to 0.27 mg/mL for propylparaben in this concentrated antibiotic suspension formulation. The extraction recoveries were 98.8-101.6%. System precision and sample extraction precision (RSD) were less than 1%.

Application of high-resolution capillary array electrophoresis with automated fraction collection for GeneCalling trade mark analysis of the yeast genomic DNA.

Capillary array instrument was applied to transcript profiling of the yeast genomic DNA using GeneCalling trade mark chemistry. The instrument integrated a 12-capillary array for DNA separation with a replaceable sieving matrix, laser-induced fluorescence detection and an automated microfraction collector. The DNA fractions, exiting the separation capillaries, were continuously deposited in a 1536-well collection plate made of agarose gel. DNA fragments recovered from selected fractions were cloned and then sequenced. Over 80% of theoretically predicted fragments could be recovered in the collected fractions, cloned and sequenced with an average redundancy of threefold. Excellent correlation of the experimentally obtained sequences with the theoretically predicted gene fragments demonstrated the suitability of capillary array electrophoresis for micropreparative recovery of DNA fragments. This approach, useful especially for rapid DNA expression profiling of unknown genes for nonsequenced organisms, demonstrates the practical capability of the prototype multicapillary fraction collector.

Persistent sciatic vessels, varicose veins, and lower limb hypertrophy: an unusual case or discrete clinical syndrome?

Persistent sciatic artery is a rare congenital anomaly with a high incidence rate of aneurysmal degeneration and risk of thromboembolization or rupture. Despite a number of recognized associations, the presence of coexistent venous anomalies is extremely rare. We present the case of a 27-year-old woman with atypical left-sided varicose veins and soft tissue hypertrophy. Imaging showed persistence of both sciatic artery and vein. Whether these anomalies are an incidental finding or represent a discrete clinical syndrome remains unclear. We emphasize that unusual distribution varicose veins may be associated with underlying persistent sciatic vessels and recommend formal duplex scan assessment for these anomalies.