Meta-analysis of adjuvant chemotherapy versus no adjuvant chemotherapy for resected stage I pancreatic cancer

BACKGROUND

To evaluate comparative outcomes of pancreatic cancer resection with or without adjuvant chemotherapy in patients with stage I pancreatic cancer.

METHODS

A systematic search of MEDLINE, CENTRAL, and Web of Science and bibliographic reference lists were conducted. All comparative studies reporting outcomes of pancreatic cancer resection for stage I cancer with or without adjuvant chemotherapy were included, and their risk of bias was assessed using the Risk Of Bias In Non-randomized Studies-of Interventions tool. Survival outcomes were analyzed using the hazard ratio and odds ratio for the time-to-event and dichotomous outcomes, respectively.

RESULTS

We included 6 comparative studies reporting a total of 6,874 patients with resected stage 1 pancreatic cancer, of whom 3,951 patients had no adjuvant chemotherapy, and the remaining 2,923 patients received adjuvant chemotherapy. The use of adjuvant chemotherapy was associated with significantly higher overall survival (hazard ratio 0.71, 95% confidence interval 0.62-0.82, P < .00001) and 2-year survival (65.1% vs 57.4%, odds ratio 1.99; 95% confidence interval 1.01-1.41, P = .04) compared to no use of adjuvant chemotherapy. However, there was no statistically significant difference in 1-year (86.8% vs 78.4%, odds ratio 1.60; 95% confidence interval 0.72-3.57, P = .25), 3-year (46.0% vs 44.0%, odds ratio 1.07; 95% confidence interval 0.90-1.29, P = .43), or 5-year survival (24.8% vs 23.3%, odds ratio 1.03; 95% confidence interval 0.80-1.33, P = .81) between the 2 groups.

CONCLUSION

Meta-analysis of best available evidence (level 2a with low to moderate certainty) demonstrates that adjuvant chemotherapy may confer survival benefits for stage I pancreatic cancer when compared to the use of surgery alone. Randomized control trials are required to escalate the level of evidence and confirm these findings with consideration of contemporary chemotherapy agents and regimens.

Meta-analysis of laparoscopic spleen-preserving distal pancreatectomy versus laparoscopic distal pancreatectomy with splenectomy: An insight into confounding by indication

AIMS

To evaluate comparative outcomes of laparoscopic spleen-preserving distal pancreatectomy (LSPDP) and laparoscopic distal pancreatectomy with splenectomy (LDPS).

METHODS

A systematic search of multiple electronic data sources and bibliographic reference lists were conducted. Comparative studies reporting outcomes of LSPDP and LDPS were considered followed by evaluation of the associated risk of bias according to ROBINS-I tool. Perioperative complications, clinically important postoperative pancreatic fistula (POPF), infectious complications, blood loss, conversion to open, operative time and duration of hospital stay were the investigated outcome parameters.

RESULTS

Nineteen studies were identified enrolling 3739 patients of whom 1860 patients underwent LSPDP and the remaining 1879 patients had LDPS. The patients in the LSPDP and LDPS groups were of comparable age (p = 0.73), gender (p = 0.59), and BMI (p = 0.07). However, the patient in the LDPS group had larger tumour size (p = 0.0004) and more malignant lesions (p = 0.02). LSPDP was associated with significantly lower POPF (OR:0.65, p = 0.02), blood loss (MD:-28.30, p = 0.001), and conversion to open (OR:0.48, p < 0.0001) compared to LDPS. Moreover, it was associated with significantly shorter procedure time (MD: -22.06, p = 0.0009) and length of hospital stay (MD: -0.75, p = 0.005). However, no significant differences were identified in overall perioperative (OR:0.89, p = 0.25) or infectious (OR:0.67, p = 0.05) complications between two groups.

CONCLUSIONS

LSPDP seems to be associated with lower POPF, bleeding and conversion to open compared to LDPS in patients with small-sized benign tumours. Moreover, it may be quicker and reduce hospital stay. Nevertheless, such advantages are of doubtful merit about large-sized or malignant tumours. The available evidence is subject to confounding by indication.

Pancreatic resection for metastasis from renal cell carcinoma: A single institution experience and meta-analysis of survival outcomes

AIMS

To evaluate short-term clinical and long-term survival outcomes of pancreatic resection for pancreatic metastasis from renal cell carcinoma (RCC).

METHODS

A retrospective evaluation of patients undergoing pancreatic resection for metastasis from RCC over a 12-years period was conducted. Furthermore, a systematic search of electronic data sources and bibliographic reference lists were conducted to identify studies investigating the same clinical question. Short-term clinical and long-term survival outcomes were evaluated. Kaplan-Meier survival plots were constructed for survival outcomes. Cox-proportional regression analysis was performed to determine factors associated with survival. Finally, meta-analysis of survival outcomes was conducted using random-effects modelling.

RESULTS

Eighteen patients underwent pancreatic resections for RCC pancreatic metastasis within the study period. The mean age of the included patients was 63.8 ± 8.0 years. There were 10(55.6 %) male and 8(44.4 %) female patients. Pancreatectomy was associated with 4(25.0 %) Clavien-Dindo (C-D) I, 5(31.3 %) C-D II, and 7(43.7 %) C-D III complications, 7(38.8 %) pancreatic fistula, 3(16.7 %) post-pancreatectomy acute pancreatitis, 1(5.6 %) delayed gastric emptying, and 1(5.6 %) chyle leak. The mean length of hospital stay was 18 ± 16.3 days. The median survival was 64 months (95 % CI 60-78). The 3-and 5-year disease-free survival rates were 83.3 % and 55.5 %, respectively. The 3-and 5-year survival rates were 100 % and 55.6 %, respectively. The pooled analyses of 553 patients demonstrated 3-and 5-year survival rates of 77.6 % and 60.7 %, respectively.

CONCLUSIONS

Pancreatectomy for RCC metastasis is associated with acceptable short-term clinical and promising long-term survival outcomes. Considering the rarity of the entity, escalation of level of evidence in this context is challenging.

Evaluation of variables predicting PFT changes for lung cancer patients treated on a prospective 4DCT-ventilation functional avoidance clinical trial

PURPOSE

Functional avoidance radiotherapy uses functional imaging to reduce pulmonary toxicity by designing radiotherapy plans that reduce doses to functional regions of the lung. A phase-II, multi-center, prospective study of 4DCT-ventilation functional avoidance was completed. Pre and post-treatment pulmonary function tests (PFTs) were acquired and assessed pulmonary function change. This study aims to evaluate which clinical, dose and dose-function factors predict PFT changes for patients treated with 4DCT-ventilation functional avoidance radiotherapy.

MATERIALS AND METHODS

56 patients with locally advanced lung cancer receiving radiotherapy were accrued. PFTs were obtained at baseline and three months following radiotherapy and included forced expiratory volume in 1-second (FEV1), forced vital capacity (FVC), and FEV1/FVC. The ability of patient, clinical, dose (lung and heart), and dose-function metrics (metrics that combine dose and 4DCT-ventilation-based function) to predict PFT changes were evaluated using univariate and multivariate linear regression.

RESULTS

Univariate analysis showed that only dose-function metrics and the presence of chronic obstructive pulmonary disease (COPD) were significant (p<0.05) in predicting FEV1 decline. Multivariate analysis identified a combination of clinical (immunotherapy status, presence of thoracic comorbidities, smoking status, and age), along with lung dose, heart dose, and dose-function metrics in predicting FEV1 and FEV1/FVC changes.

CONCLUSION

The current work evaluated factors predicting PFT changes for patients treated in a prospective functional avoidance radiotherapy study. The data revealed that lung dose- function metrics could predict PFT changes, validating the significance of reducing the dose to the functional lung to mitigate the decline in pulmonary function and providing guidance for future clinical trials.

Meta-analysis of Long-term De Novo Acid Reflux-Related Outcomes Following Sleeve Gastrectomy: Evidence Against the Need for Routine Postoperative Endoscopic Surveillance

OBJECTIVES

To evaluate the incidence of long-term de novo acid reflux-related complications following sleeve gastrectomy (SG) to determine whether routine postoperative surveillance endoscopy is necessary.

METHODS

A systematic search of Medline, Embase, CINAHL, CENTRAL, the Web of Science, and bibliographic reference lists was conducted. A proportion meta-analysis model was constructed to quantify the risk of the de novo gastro-oesophageal reflux disease (GORD), oesophagitis, and Barrett's oesophagus (BE) at least 4 years after SG. Random-effects modelling was applied to calculate pooled outcome data.

RESULTS

Thirty-two observational studies were included reporting a total of 7904 patients who underwent primary SG and were followed up for at least 4 years. The median follow-up period was 60 months (48-132). Preoperative acid-reflux symptoms existed in 19.1% ± 15.1% of the patients. The risk of development of de novo GORD, oesophagitis, and BE after SG was 24.8% (95% CI 18.6-31.0%), 27.9% (95% CI 17.7-38.1%), and 6.7% (95% CI 3.7-9.7%), respectively. The between-study heterogeneity was significant in all outcome syntheses. It was suspected that several of the included studies have not reported BE and oesophagitis because such events might not have happened in their cohorts.

CONCLUSIONS

Long-term risk of de novo GORD after SG seems to be comparable with those of the general population which questions the merit of surveillance endoscopy after SG in asymptomatic patients. De novo BE and oesophagitis after SG have not been reported by most of the available studies which may lead to overestimation of the rates of both outcomes in any evidence synthesis. We recommend endoscopic surveillance for symptomatic patients only.

Should routine surgical wound drainage after ventral hernia repair be avoided? A systematic review and meta-analysis

AIMS

To evaluate outcomes of drain use vs. no-drain use during ventral hernia repair.

METHODS

A PRISMA-compliant systematic review was conducted using the following databases: PubMed, Scopus, Cochrane database, The Virtual Health Library, Clinical trials.gov and Science Direct. Studies comparing use of drains with no-drain during ventral hernia repair (primary or incisional) were included. Wound-related complications, operative time, need for mesh removal and early recurrence were the evaluated outcome parameters.

RESULTS

Eight studies reporting a total number of two thousand four hundred and sixty-eight patients (drain group = 1214; no-drain group = 1254) were included. The drain group had a significantly higher rate of surgical site infections (SSI) and longer operative time compared with the no-drain group [odds ratio (OR): 1.63, P = 0.01] and [mean difference (MD): 57.30, P = 0.007], respectively. Overall wound-related complications [OR: 0.95, P = 0.88], seroma formation [OR: 0.66, P = 0.24], haematoma occurrence [OR: 0.78, P = 0.61], mesh removal [OR: 1.32, P = 0.74] and early hernia recurrence [OR: 1.10, P = 0.94] did not differ significantly between the two groups.

CONCLUSION

The available evidence does not seem to support the routine use of surgical drains during primary or incisional ventral hernia repairs. They are associated with increased rates of SSIs and longer total operative time with no significant advantage in terms of wound-related complications.

Characterizing Pulmonary Function Test Changes for Patients With Lung Cancer Treated on a 2-Institution, 4-Dimensional Computed Tomography-Ventilation Functional Avoidance Prospective Clinical Trial

Purpose

Four-dimensional computed tomography (4DCT)-ventilation-based functional avoidance uses 4DCT images to generate plans that avoid functional regions of the lung with the goal of reducing pulmonary toxic effects. A phase 2, multicenter, prospective study was completed to evaluate 4DCT-ventilation functional avoidance radiation therapy. The purpose of this study was to report the results for pretreatment to posttreatment pulmonary function test (PFT) changes for patients treated with functional avoidance radiation therapy.

Methods and Materials

Patients with locally advanced lung cancer receiving chemoradiation were accrued. Functional avoidance plans based on 4DCT-ventilation images were generated. PFTs were obtained at baseline and 3 months after chemoradiation. Differences for PFT metrics are reported, including diffusing capacity for carbon monoxide (DLCO), forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC). PFT metrics were compared for patients who did and did not experience grade 2 or higher pneumonitis.

Results

Fifty-six patients enrolled on the study had baseline and posttreatment PFTs evaluable for analysis. The mean change in DLCO, FEV1, and FVC was -11.6% ± 14.2%, -5.6% ± 16.9%, and -9.0% ± 20.1%, respectively. The mean change in DLCO was -15.4% ± 14.4% for patients with grade 2 or higher radiation pneumonitis and -10.8% ± 14.1% for patients with grade <2 radiation pneumonitis (P = .37). The mean change in FEV1 was -14.3% ± 22.1% for patients with grade 2 or higher radiation pneumonitis and -3.9% ± 15.4% for patients with grade <2 radiation pneumonitis (P = .09).

Conclusions

The current work is the first to quantitatively characterize PFT changes for patients with lung cancer treated on a prospective functional avoidance radiation therapy study. In comparison with patients treated with standard thoracic radiation planning, the data qualitatively show that functional avoidance resulted in less of a decline in DLCO and FEV1. The presented data can help elucidate the potential pulmonary function improvement with functional avoidance radiation therapy.

EGS P07 Management of cutaneous abscesses using the Green Whistle: A Pilot Study

Background

Cutaneous abscesses form a significant volume of emergency general surgery operating throughout the UK. They are most commonly managed with an ‘incision and drainage’ (I&D) procedure which tends to be performed with a general anaesthetic (GA). As expected with the unpredictable nature of emergency general surgery, abscesses booked for I&D under GA are often delayed to accommodate a more urgent procedure or unwell patient. Costs and theatre utilisation of abscesses managed under a general anaesthetic were obtained and analysed. A pilot study was then designed to utilise Methoxyflurane (Penthrox/Green Whistle) as an alternative to general anaesthetic for the management of abscesses.

Methods

Retrospective data of patients requiring I&D of abscesses under GA between January 2020 and January 2021 was collected. Length of stay (LOS), length of surgery (entry into theatre to out of theatre), time spent in theatre (anaesthetic room and operating theatre) and theatre complex (holding bay, anaesthetic room, operating theatre and recovery) were collected. Financial costs were also obtained. Abscesses were organised into different degrees of complexity: complex, medium and simple. ‘Simple’ abscesses were defined as such if the patient met the following criteria: &gt;18 years, ASA 2 or less, non-perianal or ischiorectal and a surgical time of 10 minutes or less.

Following the results, a pilot study was designed and proposed.

20 patients were recruited to this pilot study. Recruitment was performed on admission via the emergency portal (surgical assessment unit). To be eligible for this study, patients would need to meet the following criteria:

A patient satisfaction survey was conducted via telephone at a later date.

Results

381 patients underwent an I&D under GA. Ratio of M:F was 1.12:1. Majority of abscesses drained were perianal (n=120) and pilonidal (n=81). Majority of patients were ASA 1 or 2. 100 ‘simple’ abscesses were identified. The sum of length of stay (LOS) was 949 days. The sum of surgery time (ST) was 4.6 days. The sum of total theatre time (TT) was 14 days. The sum of time in theatre complex (TC) was 48 days.

‘Simple abscesses’ had a total LOS of 144 days, total ST of 12 hours, total TT of 69 hours and total TC of 12 days.

Pilot study: 20 patients had cutaneous abscesses drained between July and September 2021 with Penthrox. M:F ratio was 11:9. 19 patients underwent successful drainage of their abscesses whereas 1 procedure had to be abandoned due to pain. Abscess drainage was performed on the 1st day of presentation in 15 patients. There were no 30-day readmissions noted within this pilot group.

83.3% of respondents to the patient satisfaction survey rated their experience as ‘Very Good’.

Costing

Overall savings of £4,150 were calculated per patient.

Conclusions

This study aimed to look into the feasibility of a dedicated abscess pathway for patients meeting specific inclusion criteria. Overall, the results have shown that this is feasible and cost-effective. It reduces length of stay, waiting times and costs. Patients are usually discharged home the same day without any complications. Our data has shown that performing an I&D of an abscess under the Green Whistle pathway costs 30-times as less than the same abscess being managed under a GA in the theatre complex.

The pilot study has been ratified at management level and we are currently in the process of stocking Green Whistles in our Surgical Ambulatory Unit and we will shortly begin widespread training and use.

TU5.7 The Nutritional Management of Emergency and Elective Surgical Patients – Are we doing enough in the COVID-19 pandemic?

Aim

Methods

Results

Conclusion

P-O17 The Royal Stoke Green Pathway: a method to undertake safe UGI surgery during the COVID pandemic

Background

During the first wave of the COVID pandemic surgical services we paralysed globally, with cancellation of an estimated 28-million operations during the first 12 weeks.  Worryingly, surgical patient with COVID were reported to have unacceptably high peri-operative mortality, approaching 25%.  However, there was an urgent clinical need to progress with category 1 and 2 operations, to prevent disease progression and avoidable morbidity and mortality from non-COVID pathologies.  During the second and subsequent waves of the pandemic it was vital to protect patients from peri-operative COVID whilst undertaking urgent surgery safely.

Methods

Our centre developed a ring-fenced 'Green Pathway' for category 1 and 2 patients requiring surgery.  Patients were treated in physically separate area of the hospital, with no interaction between COVID and non-COVID patients, healthcare staff or facilities.  Patients self-isolated for 14-days prior to admission, and had pre- and peri-operative COVID RT-PCR tests.  We assessed outcomes for patients immediately prior to the introduction of the Green Pathway (1/10/2020) and following implementation (31/12/2020) to assess safety. Textbook outcomes for pancreatoduodenectomy were compared to assess safety and quality.  Other data suggests that UGI surgery couldn't continue in other hospitals from December 2020.

Results

There were 47 admissions to surgical HDU following category 1 and 2 upper GI operations during the study; 31 pre-pathway (PP) implementation, and 16 green pathway (GP) patients.

Median age 66-years (43-78 range) PP vs 65-years (range 42-74) GP, median ASA 3 vs 2. Median HDU length of stay (LOS) 5-days vs 7-days, and median hospital LOS 11.5-days vs 9-days for PP vs GP respectively. There were 6 cases of peri-operative COVID in PP cohort, and 1 in GP (contract following discharge). There was no mortality within either cohort. For the subgroup of patients undergoing PD: 10 patients PP, 6 patients GP, textbook outcomes were achieved in 90% vs 67% PP vs GP.

Conclusions

The implementation of the Green Pathway at our institution enabled continuation of surgery for patients with category 1 and 2 operations during the COVID pandemic with a significant reduction in peri-operative COVID infection, no mortality and no increase in length of stay. The TO rate was lower with the GP (not statistically significant), but our 4-year institution TO rate is 70.3%, comparing favourably to other studies.  This pathway has enabled safe continuation of urgent surgery during the pandemic and could be a model for adoption in other centres especially if there is resurgence of COVID cases during the coming winter.

Solid-State NMR Investigations of Extracellular Matrixes and Cell Walls of Algae, Bacteria, Fungi, and Plants

Extracellular matrixes (ECMs), such as the cell walls and biofilms, are important for supporting cell integrity and function and regulating intercellular communication. These biomaterials are also of significant interest to the production of biofuels and the development of antimicrobial treatment. Solid-state nuclear magnetic resonance (ssNMR) and magic-angle spinning-dynamic nuclear polarization (MAS-DNP) are uniquely powerful for understanding the conformational structure, dynamical characteristics, and supramolecular assemblies of carbohydrates and other biomolecules in ECMs. This review highlights the recent high-resolution investigations of intact ECMs and native cells in many organisms spanning across plants, bacteria, fungi, and algae. We spotlight the structural principles identified in ECMs, discuss the current technical limitation and underexplored biochemical topics, and point out the promising opportunities enabled by the recent advances of the rapidly evolving ssNMR technology.

EP.WE.47Cholecystectomy During COVID-19: A Single Centre Experience

Background

The COVID-19 pandemic has significantly impacted healthcare delivery globally with consequent restructuring of surgical services during the peak period and prioritisation of emergency and cancer surgery over elective operations.

We present outcomes for laparoscopic cholecystectomy during the peak period for COVID-19 in the UK and compare this with data for the same period in 2019

Methodology

This is a prospectively study. Analysis of collected data on patients who underwent laparoscopic cholecystectomy during the peak period for COVID-19 from 1st March 2020 – 30^th June 2020 (study cohort) at the Royal Stoke University Hospital. Data from the same period in 2019 (control cohort) was compared and analysed.

Results

104 patients underwent a laparoscopic cholecystectomy during the peak period compared to 217 during the same period in 2019.

Median age in the study cohort was 51.5 years (15-84 years) and 52 years (19-91 years) in the control cohort (p = 0.49). Male to Female ratio was 1:2 in the study cohort and 1:2.2 in the control cohort (p = 0.67)

Emergency admissions constituted the majority of cases and there was no statistically significant difference between both groups (61.5% vs 61.8%, p = 0.49). Most cholecystectomies were for biliary colic (41.3% vs 35.5%) and cholecystitis (37.5% vs 43.8%), and there was no statistically significant difference between both groups (p = 0.31 and p = 0.29 respectively).

Conclusion

This study demonstrates that laparoscopic cholecystectomy was feasible and safe in patients with symptomatic gall bladder disease during the peak period for COVID-19 when compared to a historic cohort in 2019.

Gap-Opening Transition in Dirac Semimetal ZrTe_{5}

We apply ^{125}Te nuclear magnetic resonance (NMR) spectroscopy to investigate the Dirac semimetal ZrTe_{5}. With the NMR magnetic field parallel to the b axis, we observe significant quantum magnetic effects. These include an abrupt drop at 150 K in spin-lattice relaxation rate. This corresponds to a gap-opening transition in the Dirac carriers, likely indicating the onset of excitonic pairing. Below 50 K, we see a more negative shift for the Te_{z} bridging site, indicating the repopulation of Dirac levels with spin polarized carriers at these temperatures. This is the previously reported 3D quantum Hall regime; however, we see no sign of a charge density wave as has been proposed.

Robotics in Cleft Surgery: Origins, Current Status and Future Directions

The field of robotic surgery is an exciting and growing field that has bolstered its way to become a mainstream application in a number of surgical disciplines. The application of robotic surgery in cleft surgery is novel and has captivated many with the benefit it provides: the slender and small arms with wrist articulation at the instrument tip; motion scaling; tremor elimination; and high fidelity, three-dimensional visualization make the robot a very attractive platform for use in confined spaces with small surgical targets. The story of the origin of robotic surgery in cleft surgery is an interesting one, and one that has arisen from other allied surgical specialities to render robotic cleft surgery as its own specialised field. A field that has coined its own terms and has demonstrated a number of applications for its use. This review details the origins of robotic cleft surgery, its evolution and its current status and elaborates on future directions to enhance its application.

Use of Augmented Reality in Reconstructive Microsurgery: A Systematic Review and Development of the Augmented Reality Microsurgery Score

BACKGROUND

 Augmented reality (AR) uses a set of technologies that overlays digital information into the real world, giving the user access to both digital and real-world environments in congruity. AR may be specifically fruitful in reconstructive microsurgery due to the dynamic nature of surgeries performed and the small structures encountered in these operations. The aim of this study was to conduct a high-quality preferred reporting items for systematic reviews and meta-analyses (PRISMA) and assessment of multiple systematic reviews 2 (AMSTAR 2) compliant systematic review evaluating the use of AR in reconstructive microsurgery.

METHODS

 A systematic literature search of Medline, EMBASE, and Web of Science databases was performed using appropriate search terms to identify all applications of AR in reconstructive microsurgery from inception to December 2018. Articles that did not meet the objectives of the study were excluded. A qualitative synthesis was performed of those articles that met the inclusion criteria.

RESULTS

 A total of 686 articles were identified from title and abstract review. Five studies met the inclusion criteria. Three of the studies used head-mounted displays, one study used a display monitor, and one study demonstrated AR using spatial navigation technology. The augmented reality microsurgery score was developed and applied to each of the AR technologies and scores ranged from 8 to 12.

CONCLUSION

 Although higher quality studies reviewing the use of AR in reconstructive microsurgery is needed, the feasibility of AR in reconstructive microsurgery has been demonstrated across different subspecialties of plastic surgery. AR applications, that are reproducible, user-friendly, and have clear benefit to the surgeon and patient, have the greatest potential utility. Further research is required to validate its use and overcome the barriers to its implementation.

Structure Change and Rattling Dynamics in Cu12Sb4S13 Tetrahedrite: an NMR Study

We present a ⁶³Cu and ⁶⁵Cu NMR study of Cu₁₂Sb₄S₁₃, the basis for tetrahedrite thermoelectric materials. In addition to electronic changes observed at the T_c = 88 K metal-insulator transition, we find that locally there are significant structural changes occurring as the temperature extends above T_c, which we associate with Cu atom displacements away from symmetry positions. Spin-lattice relaxation rates (1/ T₁) are dominated by a quadrupolar process indicating anharmonic vibrational dynamics both above and below T_c. We used a quasiharmonic approximation for localized anharmonic oscillators to analyze the impact of Cu rattling. The results demonstrate that Cu-atom rattling dynamics extends unimpeded in the distorted structural configuration below T_c and provide a direct measure of the anharmonic potential well.

Native defects and impurity band behavior in half-Heusler thermoelectric NbFeSb

Native defects are identified that dominate the electronic behavior and generate impurity-band states in the promising thermoelectric NbFeSb.

Quantum phase transitions in the Kondo-necklace model: perturbative continuous unitary transformation approach

The Kondo-necklace model can describe magnetic low-energy limit of strongly correlated heavy fermion materials. There exist multiple energy scales in this model corresponding to each phase of the system. Here, we study quantum phase transition between the Kondo-singlet phase and the antiferromagnetic long-range ordered phase, and show the effect of anisotropies in terms of quantum information properties and vanishing energy gap. We employ the 'perturbative continuous unitary transformations' approach to calculate the energy gap and spin-spin correlations for the model in the thermodynamic limit of one, two, and three spatial dimensions as well as for spin ladders. In particular, we show that the method, although being perturbative, can predict the expected quantum critical point, where the gap of low-energy spectrum vanishes, which is in good agreement with results of other numerical and Green's function analyses. In addition, we employ concurrence, a bipartite entanglement measure, to study the criticality of the model. Absence of singularities in the derivative of concurrence in two and three dimensions in the Kondo-necklace model shows that this model features multipartite entanglement. We also discuss crossover from the one-dimensional to the two-dimensional model via the ladder structure.

Anti-oxidant effect of flavonoids on hemoglobin glycosylation

A high glucose concentration has been found to lead to the glycosylation of amino groups of lysine residue in proteins. The addition of reducing agent not only prevents this reaction but also reverses it. On the other hand, flavonoids which found in plant sources have antioxidant properties. Since the glycosylation of protein is an oxidation reaction, therefore, antioxidants should be able to prevent this reaction. In this study, the best concentration and time to incubate glucose with hemoglobin was investigated. Then the glycosylation degree of hemoglobin in the presence of flavonoids and their absence was measured by means of a colorimetric method. Different concentration of flavonoids (Quercetin, Rutin, Kaempferol) were used. The preventing effect on hemoglobin glycosylation by the three concentrations; 0.5, 5, 10 micrograms/ml was estimated as follows: for Rutin; 11%, 27%, 42%, Quercetin; 3%, 37%, 52%, Kaempferol; 10%, 12%, 15% respectively. So, the in vivo effect should be investigated and then plants that containing flavonoids can be utilized to prevent or treat complication of diabetes.