A first-principles model of copper-boron interactions in Si: implications for the light-induced degradation of solar Si

The recent discovery that Cu contamination of Si combined with light exposure has a significant detrimental impact on carrier life-time has drawn much concern within the solar-Si community. The effect, known as the copper-related light-induced degradation (Cu-LID) of Si solar cells, has been connected to the release of Cu interstitials within the bulk (2016 Sol. Energy Mater. Sol. Cells 147 115-26). In this paper, we describe a comprehensive analysis of the formation/dissociation process of the CuB pair in Si by means of first-principles modelling, as well as the interaction of CuB defects with photo-excited minority carriers. We confirm that the long-range interaction between the [Formula: see text] cation and the [Formula: see text] anion has a Coulomb-like behaviour, in line with the trapping-limited diffusivity of Cu observed by transient ion drift measurements. On the other hand, the short-range interaction between the d-electrons of Cu and the excess of negative charge on [Formula: see text] produces a repulsive effect, thereby decreasing the binding energy of the pair when compared to the ideal point-charge Coulomb model. We also find that metastable CuB pairs produce acceptor states just below the conduction band minimum, which arise from the Cu level emptied by the B acceptor. Based on these results, we argue that photo-generated minority carriers trapped by the metastable pairs can switch off the Coulomb interaction that holds the pairs together, enhancing the release of Cu interstitials, and acting as a catalyst for Cu-LID.

The cost-effectiveness of bevacizumab for the treatment of advanced ovarian cancer in Canada

BACKGROUND

The overall survival (os) analysis of the icon7 trial demonstrated that frontline ovarian cancer patients with a high risk of progression (stage iii suboptimally debulked, and stage iii or iv with unresectable disease) benefited from the addition of bevacizumab to standard chemotherapy compared with standard chemotherapy alone. The objective of the present study was to investigate the cost-effectiveness, from a Canadian publicly funded perspective, of adding bevacizumab to frontline treatment of ovarian cancer at high risk of progression.

METHODS

An area-under-the-curve, Markov-structured model was used to estimate the cost-effectiveness of the treatments. Long-term progression-free survival (pfs) and os were extracted from the icon7 trial (subgroup at high risk of relapse) and extrapolated by parametric time-to-event functions over a time horizon of 10 years. Canadian pfs health state utility values were obtained from the EQ-5D (EuroQoL Group, Rotterdam, Netherlands) questionnaires in the icon7 high-risk patient population. Canadian post-progression utility values were consistent with those for other gynecologic cancers. Cost inputs were informed by public sources. An annual 5% efficacy and cost discount rate was applied. A probabilistic sensitivity analysis and one-way sensitivity analyses were conducted.

RESULTS

Ovarian cancer patients at high risk of progression receiving bevacizumab plus standard chemotherapy experienced a mean incremental quality-adjusted life year (qaly) gain of 0.374 years. At an additional cost of $35,901.54, the incremental cost-effectiveness ratio (icer) for the addition of bevacizumab to standard chemotherapy, relative to standard chemotherapy alone, was $95,942 per qaly.

CONCLUSIONS

No formal health technology assessment willingness-to-pay threshold exists in Canada. However, at a threshold of $100,000 per qaly, bevacizumab in addition to chemotherapy is a cost-effective alternative for ovarian cancer patients who are at high risk of progression (stage iii suboptimally debulked, and stage iii or iv with unresectable disease). Using the $100,000 per qaly threshold in a probabilistic sensitivity analysis, it was determined that, compared with standard chemotherapy, the addition of bevacizumab to chemotherapy is cost-effective in 56% of tested scenarios.

Liver retraction system by C3-muco-adhesive polymer films for laparoscopic surgery

BACKGROUND

Conventional laparoscopic instruments used for retraction may cause trauma at the retraction site. Alternative retraction/lifting especially of heavy solid organs such as the liver may be obtained by other means. The present study was designed to explore the use of C3-muco-adhesive polymers (C3-MAPs), which exhibit strong binding to the liver shortly after application to the organ and which retain strong adhesion for sufficient time, to enable sustained retraction during laparoscopic operations.

METHODS AND MATERIALS

C3-muco-adhesive polymers were produced specifically for the study. In an ex vivo experimental set-up, discs of C3-MAPs were placed on the surface of porcine livers for adhesion and retraction studies involving objective measurements by tensiometry.

RESULTS

Experiments were carried out on 14 porcine livers. The force required to detach the C3-MAPs from the liver exceeded 2.0 N 30 s after application. The adhesion force by C3-MAPs files was sufficient to enable sustained retraction force necessary for exposure of the gall bladder, which was achieved by a mean retraction force of 4.85 N (SD = 0.63). This was sustained for a mean of 130 min (range 17.0-240.0). In the adhesion studies, the forces at 30 s required to detach the polymer discs from the liver exceeded 20 N (upper limit of the load cells of the Instron). The duration of the adhesion enabled sustained optimal gall bladder exposure for periods ranging from 17 to 240 min, with a mean of 130 ± 91 min.

CONCLUSIONS

The results of the present study demonstrate that the adhesion and retraction properties of the engineered C3-MAP films are sufficient to enable complete exposure of the gall bladder for a period exceeding 1 h, confirming their potential for atraumatic retraction in laparoscopic and other minimal-access surgical approaches.

Understanding Concerns About Treatment-as-Prevention Among People with HIV who are not Using Antiretroviral Therapy

The use of antiretroviral therapy to prevent HIV transmission is now advocated in many settings, yet little research has documented the views of people with HIV. Semi-structured interviews were conducted in Australia between 2012 and 2014 with 27 HIV-positive people not using treatment at the time of interview. Thematic analysis of views on treatment-as-prevention found that while many participants recognised potential prevention benefits, only a minority was in support of initiating treatment solely to achieve those benefits. A range of uncertain or critical views were expressed regarding who would benefit, risk reduction, and changing treatment norms. Participants resisted responsibility narratives that implied treatment should be used for the public good, in favour of making considered decisions about their preferred approach to managing HIV. Engaging communities in dialogue and debate regarding the risks and benefits of treatment will be critical if this new prevention strategy is to engender public trust.

Structural plasticity of helical nanotubes based on coiled-coil assemblies

Numerous instances can be seen in evolution in which protein quaternary structures have diverged while the sequences of the building blocks have remained fairly conserved. However, the path through which such divergence has taken place is usually not known. We have designed two synthetic 29-residue α-helical peptides, based on the coiled-coil structural motif, that spontaneously self-assemble into helical nanotubes in vitro. Using electron cryomicroscopy with a newly available direct electron detection capability, we can achieve near-atomic resolution of these thin structures. We show how conservative changes of only one or two amino acids result in dramatic changes in quaternary structure, in which the assemblies can be switched between two very different forms. This system provides a framework for understanding how small sequence changes in evolution can translate into very large changes in supramolecular structure, a phenomenon that may have significant implications for the de novo design of synthetic peptide assemblies.

Self-powered wireless carbohydrate/oxygen sensitive biodevice based on radio signal transmission

Here for the first time, we detail self-contained (wireless and self-powered) biodevices with wireless signal transmission. Specifically, we demonstrate the operation of self-sustained carbohydrate and oxygen sensitive biodevices, consisting of a wireless electronic unit, radio transmitter and separate sensing bioelectrodes, supplied with electrical energy from a combined multi-enzyme fuel cell generating sufficient current at required voltage to power the electronics. A carbohydrate/oxygen enzymatic fuel cell was assembled by comparing the performance of a range of different bioelectrodes followed by selection of the most suitable, stable combination. Carbohydrates (viz. lactose for the demonstration) and oxygen were also chosen as bioanalytes, being important biomarkers, to demonstrate the operation of the self-contained biosensing device, employing enzyme-modified bioelectrodes to enable the actual sensing. A wireless electronic unit, consisting of a micropotentiostat, an energy harvesting module (voltage amplifier together with a capacitor), and a radio microchip, were designed to enable the biofuel cell to be used as a power supply for managing the sensing devices and for wireless data transmission. The electronic system used required current and voltages greater than 44 µA and 0.57 V, respectively to operate; which the biofuel cell was capable of providing, when placed in a carbohydrate and oxygen containing buffer. In addition, a USB based receiver and computer software were employed for proof-of concept tests of the developed biodevices. Operation of bench-top prototypes was demonstrated in buffers containing different concentrations of the analytes, showcasing that the variation in response of both carbohydrate and oxygen biosensors could be monitored wirelessly in real-time as analyte concentrations in buffers were changed, using only an enzymatic fuel cell as a power supply.

The Concise Guide to PHARMACOLOGY 2013/14: overview

The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties from the IUPHAR database. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. This compilation of the major pharmacological targets is divided into seven areas of focus: G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors & Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and GRAC and provides a permanent, citable, point-in-time record that will survive database updates.

Vertical rectus abdominis myocutaneous flap reconstruction of the perineal defect after abdominoperineal excision is associated with low morbidity

AIM

To examine the short-term outcomes of perineal reconstruction with a vertical rectus abdominis myocutaneous (VRAM) flap following abdominoperineal excision (APE).

METHOD

Retrospective case note review of all patients undergoing APE and primary VRAM reconstruction between July 2001 and February 2012 in a district general hospital tertiary referral centre for APE. Complications were categorized using the Clavien-Dindo classification, which grades complications from I to V in order of increasing severity.

RESULTS

Fifty-five consecutive patients (31 men, median age 65, range 38-84 years) underwent APE with VRAM flap reconstruction, 15 for anal cancer and 40 for rectal cancer. Median length of stay was 11 days but was significantly shorter in the laparoscopic group compared with the open group (8 vs 12 days; P < 0.01) and in patients who did not experience any complications (P < 0.05). Four patients (7%) had major complications (Grade 3 and above) directly related to the flap or donor site.

CONCLUSION

VRAM reconstruction of the perineum can be safely performed following APE with results that compare favourably with other techniques. Most flap complications are minor, although these are still associated with an increase in the length of hospital stay.

Placental hyperinflation and the risk of adverse perinatal outcome

OBJECTIVES

To determine the pathological basis and clinical associations of excessively thick placentae observed at second-trimester ultrasound examination.

METHODS

In a retrospective cohort of 19 singleton high-risk second-trimester pregnancies noted to have a placental length-to-maximum thickness ratio ≤ 2.0, maximum sonographic placental thickness was correlated with clinical outcome, maximum placental thickness after delivery and placental pathological findings. Results were compared with those of an intermediate group of 21 high-risk pregnancies with normal placental dimensions and a control group of 18 low-risk pregnancies also with normal placental dimensions. Increased maximum placental thickness (> 28 mm) and abnormal placental deflation following delivery (pathology - sonography difference in maximum placental thickness < -2 mm) were defined by the upper and lower quartile values, respectively, in the control group.

RESULTS

The study group exhibited significantly more adverse outcomes and gross pathological placental features compared with both intermediate and control groups. Despite increased sonographic maximum placental thickness in the study group (median, 55 (range, 40-75) mm compared with both the intermediate group (median, 27 (range, 22-41) mm, P < 0.0001) and the control group (median 26 (range, 23-36) mm, P < 0.0001)), all three groups had similar maximal placental thickness following delivery (study group: median, 24 (range, 10-50) mm vs intermediate group: median, 27 (range, 15-40) mm, P = 0.82 and vs control group: median, 28.5 (range, 18-44), P = 0.42). Pathology-sonography difference in maximum placental thickness in the study group (median, -30 (range, -42 to 0) mm) was significantly greater than that in either the intermediate (median, -2 (range, -11 to 9) mm, P < 0.0001) or the control (median, 1.5 (range, -10 to 18) mm, P < 0.0001) group and was significantly associated with abnormal development of the gas-exchanging placental villi (distal villous hypoplasia) (P = 0.0001).

CONCLUSIONS

Increased second-trimester sonographic maximum placental thickness represents a pathological finding associated with severe adverse perinatal outcome. This observation is due to overinflation of the intervillous space by maternal blood rather than to adaptive formation of functional placental tissue.

HbA(1c) as a diagnostic tool for diabetes and pre-diabetes: the Bangladesh experience

AIMS

To evaluate HbA(1c) as a tool for the diagnosis of diabetes and pre-diabetes (impaired glucose tolerance and/or impaired fasting glucose) and to identify the optimal cut-off values suitable for a Bangladeshi population.

METHODS

In this cross-sectional survey in a rural community, 2293 randomly selected individuals aged ≥ 20 years without prior history of diabetes were included. HbA(1c) and other clinical covariates necessary for the diagnosis of diabetes were recorded. Diabetes and pre-diabetes were defined according to the World Health Organization 1999 criteria. The receiver operating characteristic curve was used to determine the performance of HbA(1c).

RESULTS

The prevalences of diabetes and pre-diabetes were 7.9 and 8.6%, respectively. Based on receiver operating characteristic curve analysis, an HbA(1c) cut-off value of ≥ 42 mmol/mol (≥ 6.0%) gave an optimal sensitivity of 86.2% and specificity of 93.3%, with an area under the curve of 0.949 to predict diabetes using the oral glucose tolerance test as the gold standard; a cut-off value of ≥ 38 mmol/mol (≥ 5.6%) gave an optimal sensitivity of 68.0% and specificity of 66.4%, with an area under the curve of 0.714 to predict pre-diabetes. In subjects at high risk of diabetes, HbA(1c) ≥ 42 mmol/mol (≥ 6.0%) showed higher sensitivity than fasting plasma glucose ≥ 7.0 mmol/l, 2-h plasma glucose ≥ 11.1 mmol/l and HbA(1c) ≥ 48 mmol/mol (≥ 6.5%).

CONCLUSIONS

An HbA(1c) cut-off value of ≥ 42 mmol/mol (≥ 6.0%) was highly sensitive and specific in diagnosing diabetes mellitus. This optimal cut-off level may be suitable as a diagnostic criterion for diabetes in a Bangladeshi population.

Finding out about sperm banking: what information is available online for men diagnosed with cancer?

Sperm banking is routinely offered to men where there is a risk of infertility following cancer treatment but uptake is lower than expected. Since these men may turn to the internet for information, we used the search engine www.google.com to identify the material available about sperm banking and fertility preservation options. Sixty-six resources (NHS/Private Clinic, Charity, Press Releases, General and Forums/Blogs) fulfilled the criteria for inclusion and were examined for quality including readability, layout and content. The most frequently reported information related to: (1) effects of cancer treatment on fertility (77.3%); (2) reasons to bank sperm (69.7%); and (3) fertility recovery after treatment (57.6%). Information about maintaining contact with the sperm bank (18.2%) and disposal of banked samples (10.6%) was less often included. The quality of information available on the Internet about sperm banking was variable. The readability of all resources was assessed as 'fairly difficult', i.e. reading skills required were too complex for the average member of the public to understand. Furthermore, visual presentation of material (e.g. lay out) did not facilitate easy reading. More attention should be given to information about longer-term issues, such as fertility recovery and the use or disposal of banked sperm.

Does use of antiretroviral therapy regimens with high central nervous system penetration improve survival in HIV-infected adults?

OBJECTIVES

The aim of the study was to determine whether combination antiretroviral therapy (cART) with high central nervous system penetration-effectiveness (CPE) rank (neurocART) is associated with increased survival benefit compared with non-neurocART.

METHODS

Prospective data were examined for HIV-positive patients in the Asia Pacific HIV Observational Database who had commenced cART. CPE rank was calculated using the 2010 rankings process. NeurocART status was assigned to regimens with a CPE rank of 8 or more. Survival was analysed using Cox proportional hazards models with covariates updated at changes in cART regimen and with deaths up to 90 days after regimen cessation attributed to that regimen. Sensitivity analyses were conducted to examine the robustness of analysis assumptions.

RESULTS

Among 5882 patients, 308 deaths occurred. The hazard ratio (HR) for neurocART use was 0.89 (P=0.35) when data were stratified by cohort and adjusted for age, mode of HIV exposure, hepatitis B virus coinfection, AIDS-defining illness, CD4 count (cells/μL) and regimen count. Sensitivity analyses showed similar nonsignificant results. We also examined a composite endpoint of AIDS-defining illness or death (HR=0.93; P=0.61), baseline regimen as neurocART (HR=0.95; P=0.69), CPE category (P=0.71) and prior neurocART duration (P=0.16). No association between CD4 cell count and neurocART use was observed (P=0.52).

CONCLUSIONS

Our findings do not show a significant overall survival benefit associated with neurocART compared with cART. The potential benefit associated with neurocART in terms of prevention of neurocognitive impairment did not translate into an improvement in overall survival in this population. These findings were limited by the low incidence of associated mortality. Further studies and more extensive data are needed to address these limitations.