bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of rail-wheel contact problem by analytical and numerical approaches
Authors: Sirata G G , Lemu H G , Waclawiak K , Jelila Y D
Published: November 2021

This study presents the rail wheel contact problems under normal and tangential categories. Both analytical and numerical approaches were used for modelling, where the analytical approach assumed elliptical contact patches based on the Hertz theory. In the numerical approach, 3D finite element models were used to investigate non-elliptical contact patches. The only elastic material model was considered in the case of Hertz theory. However, in the case of finite element analysis, both elastic and elastoplastic material models were used to simulate the material's behavior under the applied load. The elastoplastic material model was used to determine the amount of stress at which the plastic deformation starts, which enables determining the rail wheel's critical load. The commercial software ABAQUS was employed for 3D modeling and contact stress analysis. The study shows maximum stress at 3 mm from the rail wheel contact surface when the maximum load of 85 kN is applied. This initiates the cracks in the subsurface and causes the portion of the rail wheel to break off in the form of spalling after a certain time.
Local and global assessments of a subsea riser-spool connection under dropped impact loads
Authors: Liu Z , Igland R , Bruaseth S
Published: November 2021

Subsea riser tube and spool is often used together to connect the riser of jacket to flowline or pipeline. Due to its limited size (less than 200 m), the location is within the lifting zones of the platform. Consequently, the dropped object hazard has potential high risk and needs to be checked. This paper presents a numerical study on accessing the structural dynamics of a subsea riser connection under the dropped container impact loads. De-coupled local and global models were established. The impact impulse was obtained from local impact analysis by Abaqus Explicit solver, in which deformations from container and pipeline are both captured. The impact energy level is in line with the risk assessment. The global model was built by ANSYS APDL macros. A simple input file is only needed for end users. The nonlinear pipe and soil interaction are included in a simplified manner. The model comprises of static and dynamic analysis parts. The static analysis captures the in-place configuration and the functional loads. The dynamic analysis is a restart with inherited stress state from static analysis. The impact impulse was applied by point loads in a certain time range. The nonlinear soil stiffness was approached by spring elements (compression only). The dynamic analysis was done in a longer time, ensuring to capture any dynamic effects. The interface loads at the riser stick-out and riser anchor are both extracted and discussed. It is shown that present structure design can withstand the dropped loads at the input energy level.
Capacity of concrete structures with corroded reinforcement and prestressing tendons
Authors: Sigvaldsen M , Ersdal G , Markeset G , Samarakoon S , Langeteig M
Published: November 2021

The main degradation mechanism for concrete structures is corrosion of the reinforcement and prestressing tendons. Management of structures with such degradation requires detailed understanding of their remaining strength and safety and if necessary, make a decision regarding repairs or replacement of the structure or components. Some simplified methods for estimating the residual capacity of concrete structures do exist, primarily based on a reduction of the flexural capacity equal to the percentage of the corroded area. In this paper, a more physical understanding and description of the influence of corrosion on the strength is investigated, based on a reduction of the area of the reinforcement and prestressing tendons both due to uniform corrosion and pitting corrosion. The results of these models are successfully compared to experimental results of concrete beams with corrosion. Particularly corrosion of post-tensioned tendons is a concern for concrete structures. Some disturbing examples of collapse of concrete bridges have been seen as a result of such corrosion. The paper highlights the importance of the significant strength loss of the reinforcement as a result of corrosion itself, but also the loss of ductility due to possible hydrogen embrittlement and hydrogen induced stress corrosion cracking. The paper also suggests sulphate reducing bacteria as a possible explanation to corrosion issues related to corrosion of post-tensioned tendon structures where no chloride is found. The aim of the paper is to propose a method to calculate a lower bound estimate of the remaining capacity of concrete beams with corrosion damage to reinforcement and to the prestressing tendons.
A methodology for collecting donning times of thermal protective immersion suits intended to be worn by passengers on vessels operating in cold environments
Authors: Brünig R , Galea E R , Batalden B M , Oltedal H A
Published: November 2021

Adequate thermal protection for passengers travelling on-board vessels in cold climate regions, such as that provided by thermal protective immersion suits (TPIS), enhances passenger survivability in emergency situations, in particular those requiring the abandonment of the vessel. As emergency abandonment is a time critical process, it is essential to consider the time required to correctly don the TPIS. Testing standards, such as the International Maritime Organization guidelines, require that TPIS must be able to be donned within 2 minutes. Unfortunately, current practices quantifying donning times are questionable and so there is a limited evidence base that reliably quantifies donning times required by typical passengers. This paper presents a test procedure designed to reliably quantify the time required by test subjects to don the TPIS. Furthermore, the procedure assesses the donning correctness – a TPIS that is incorrectly donned is unlikely to offer appropriate thermal protection. The paper will also discuss the deficiencies in current practices to assess required donning time.
Study of the metocean conditions for the Russian Arctic Shelf development projects approaches and results: Review for the period of 2012-2021
Authors: Buzin I V , Gudoshnikov Y P , Nesterov A V , Naumov A K , Skutina E A , Smirnov K G , Andreev O M , Vinogradov R A , Novikov S A , Skutin A A
Published: November 2021

The FSBI AARI is the leading State Scientific Center of Russia, which is involved in studying the natural environment of the Polar Regions and its impact on human activity for over a century. In the last 30 years, the new sphere of activity, dealing with the specialized metocean (including ice) surveys for the purpose of Arctic Offshore Development was successfully developed here. For the most important Arctic Offshore projects the full set of these specialized studies was conducted by the Institution. The paper gives an overview of AARI’s scientific and applied scope and tasks, a general chronology of the surveys on the Russian Arctic Shelf since 1990-s, a description of the main study methods, and an overview of the main results of studies for the last ten years (2012-2021). It is demonstrated that the role of detailed ice and metocean surveys is often determinative in sense of design and construction of Arctic Offshore objects.
Identifying challenges facing reliable supply chains and ways to mitigate then for mining in the Baffin Bay region
Authors: Taarup-Esbensen J , Gudmestad O T
Published: November 2021

There are substantial economic opportunities in extracting minerals in the Arctic region. However, it has proven difficult for operators to ensure reliable supply chains (SCs) north of the Arctic Circle. This paper uses a case study approach to illustrate the challenges of SCs reliability for mining projects in the northern Baffin Bay and on Greenland, discussing the technological and organisational developments that can mitigate them. A bow-tie approach shows the challenges faced by the industry and the effect of mitigating initiatives. We conclude that increased traffic will require technological, organisational and infrastructure developments to manage SC hazards and increase SC reliability. The available protective and preventive barriers have focused on avoiding periods where hazards could impact SC reliability. However, this strategy is unsustainable in the long term as a viable strategy for mining operations. It exposes the operations to Arctic hazards that are difficult to mitigate when time is limited. The consequence is that SCs often lack access to effective Arctic hazard barriers, ensuring increased SC reliability.
Generative adversarial networks for modeling reservoirs with permeability anisotropy
Authors: Guliev R
Published: November 2021

The geological model is a main element in describing the characteristics of hydrocarbon reservoirs. These models are usually obtained using geostatistical modeling techniques. Recently, methods based on deep learning algorithms have begun to be applied as a generator of a geologic models. However, there are still problems with how to assimilate dynamic data to the model. The goal of this work was to develop a deep learning algorithm - generative adversarial network (GAN) and demonstrate the process of generating a synthetic geological model:

• Without integrating permeability data into the model

• With data assimilation of well permeability data into the model

The authors also assessed the possibility of creating a pair of generative-adversarial network-ensemble smoother to improve the closed-loop reservoir management of oil field development.
Optimization approach for Arctic field development design using subsea production systems
Authors: Beskhizhko Y V
Published: November 2021

Russian experience in the design of trunk pipelines and Arctic studies have been used to develop an efficient model and method for Arctic field development design using the subsea production system (SPS). Compared to 2D models used in the past, the new design technique offers an opportunity to make 3D models and can be used for optimization of offshore field development projects. The proposed optimization model is based on the Bellman - Ford algorithm developed for 3D networks. This approach has been used for the first time to capture key features and specific subsea production system design processes. The algorithm and block diagrams developed for the proposed SPS design method is universal. This method can be used to address tasks of a more general nature. Optimization of the particular case between a single start point (well location) and single end point (SPS facility) is implemented as a separate software package, but the scope of applications is not limited by such cases and may be extended even further. It can also be very efficient for Arctic subsea field development.
Development of the digital oil and gas complex in Arctic areas of Russia
Authors: Dmitrievskiy A N , Eremin N A , Kondratyuk A T , Basnieva I K
Published: November 2021

This article examines the issues of digital modernization of the oil and gas complex of Russia, the evolution of digital oil and gas technologies. The main results of research work in the field of creating digital technologies for preventing complications and accidents, transferring drilling data in blockchain format, monitoring the state of pipelines using magnetic tomography are briefly outlined. The digital modernization strategy is aimed at large-scale digitalization of oil and gas production facilities and lays a reliable basis for the growth of capital productivity of fields in the long term. The approach is based on improving the quality of management, analyzing the effectiveness of control actions when using an integrated model or a digital twin of the field. The integrated application of digital technologies for effective management is the basis for cost optimization, ensuring the transition to robotic control, and increasing the capital productivity ratio of key gas assets. These solutions are especially effective in regions with difficult natural and climatic conditions or undeveloped infrastructure, Arctic fields. The proposed integrated approach makes it possible to extend the periods of profitable exploitation of gas fields at the stage of declining production and complicated production conditions. By the end of 2025, the number of digital fields using technologies for processing Big Geo Data will exceed 10% of the total number of oil and gas fields in Russia.
Maintenance philosophy for an unmanned platform: A case study for an Offshore wind substation
Authors: Tolstow K T , Beiky A , El-Thalji I
Published: November 2021

Unmanned installations introduce new challenges for the operations and maintenance. In many offshore windfarms there is a need for offshore substations and these substations can be designed as unmanned installations. Thus, the purpose of this paper is to review and discuss the available maintenance philosophies for unmanned substation platforms and as a result, propose a suitable maintenance philosophy for this type of installations with regards to key performance indicators such as high availability, low maintenance man-hours and minimal fixed maintenance campaigns. It is concluded that maintenance philosophy for unmanned substation shall consider the DIP (Design out and Intelligent preventive maintenance) concept, where the potential benefits of risk-based maintenance, design-out, predictive, and prescriptive maintenance are unlocked. To illustrate the utilization of proposed philosophy, a case study related to cooling system of a substation is presented
The use of limestone sludge for the geopolymer preparation
Authors: Kubatova D , Khongova I , Krejci Kotlanova M , Zezulova A , Bohac M
Published: November 2021

The study investigates the effect of sludge waste from mining and washing of limestone on the properties of geopolymer binders based on metakaolin and blast furnace slag. The effect of adding two types of limestone sludge on workability, setting time, compressive strengths, durability and pore distribution was investigated. Limestone sludge was dosed in an amount of 0–30 %. Sodium water glass was used as an alkaline activator in the ratio of 5:4. A linear correlation between the flowability and limestone sludge content was observed, and very satisfactory results of compressive strength after 90 days were obtained for samples with sodium water glass (about 55 MPa). The positive effect of CaCO3 on strength was confirmed. The increased content of clay components resulted in a reduction of compressive strength.
Impact of the curing conditions and carbon dioxide ingress on heavyweight concrete
Authors: Cepcianska J , Dragomirova J , Kuzielova E , Zemlicka M , Palou M T
Published: November 2021

The present work investigates the influence of curing conditions on the mechanical and physical properties of heavyweight concrete. The prismatic bars of 40 mm × 40 mm × 160 mm dimension were cured in a climatic chamber (relative humidity 30%, average temperature 26°C), wet (100% of humidity, average room temperature 26°C) and CO2 chamber-wet (relative humidity 90%, average temperature 50°C and average CO2 concentration 20 %) conditions for 2, 7, 28 and 90 days. Density, compressive strength, dynamic modulus of elasticity, and longitudinal shrinkage were determined at different ages of curing. Mercury Intrusion Porosimetry was used to analyze and determine the influence of carbonation on pore structure evolution. Samples cured under CO2-wet conditions showed a higher compressive strength (54.05, 66.83, 84.98, 96.35 MPa) compared to that of the samples exposed to wet (45.49, 65.87, 78.91, 93.80 MPa) and dry (39.62, 46.52, 48.45, 45.28 MPa) conditions at all ages. The dynamic modulus of elasticity of CO2-wet cured samples (53.02, 51.48, 59.24, 67.60 GPa) was lower than that of samples cured in wet conditions (59.82, 66.76, 78.84, 80.27, GPa), but higher than that of dry-cured samples (45.74, 45.73, 43.91, 44.62 GPa). The density of the samples exposed to all curing conditions was higher than 3800 kg/m3. Carbonation led to a decrease in total porosity (from 10% to 20%) and an increase in density (from 320 to 390 kg/m3). Also, the time and curing conditions have strongly influenced the pore structure. The precipitation of calcium carbonate in the matrix of concrete and the acceleration of hydration reaction under wet conditions has led to a decrease in porosity.
Development of rapid set mortar for additive manufacturing
Authors: Nespor B , Bohac M , Nejedlik M
Published: November 2021

The study presents the development results of blended cement mortars for additive manufacturing. The goal was to achieve a balanced rheological behaviour of the fresh mixture through optimal granulometry, suitable grain shape and the choice of micro-admixtures. The article closely describes the granulometric and rheological characterization of the proposed ternary and quaternary blended mortar mixtures with various SCM’s. The print quality and shape stability of the promising mortars and the researched 3DP mixes were evaluated during incremental layering for comparison. The performed experiments confirmed that the mixtures containing blast furnace slag, quartz powder and metakaolin are more plastic and allow faster layering in height. The slaked lime-enriched mixture has excellent plasticity and is able to resist deformation during overlaying, the printed layers are without surface defects. The small addition of polypropylene fibre (0.08 wt.%) improves the plasticity and shape retention ability.
Effect of alkali cation type on the plasticizing effect of lignosulfonate in alkali-activated systems
Authors: Valeriia Iliushchenko , Vlastimil Bílek , Lukáš Kalina , Petr Hrubý , Tomáš Opravil , Jiři Bojanovský
Published: November 2021

Rheological properties of alkali-activated systems are significantly affected by the nature of the alkaline activator. Hydroxide-activated systems’ workability is typically lower than that of alkali-activated systems but can be improved by lignosulfonate plasticizer. However, the lignosulfonate plasticizer’s effectivity depends on the dosage of lignosulfonate, the nature of hydroxide and pH of their solutions. Therefore, in this study, the effectiveness of lignosulfonate plasticizer with respect to alkali ion type (Na+, K+, Li+) in alkali hydroxide-activated systems based on ground granulated blast furnace slag was evaluated. The concentration of the alkaline activator (NaOH, KOH and LiOH) was the same in all cases of 4M, the superplasticizer dosage was 0 %, 0.5 % and 1.0 % of dry matter of lignosulfonate plasticizer to the slag weight. Rheological properties were determined using a rotational rheometer equipped with vane in-cup geometry working in oscillation amplitude sweep mode, from which critical strain and corresponding viscoelastic variables were obtained.
Hydrothermal synthesis and characterisation of zeolites from metakaolin and water glass
Authors: Krejci Kotlanova M , Dolnicek Z , Khongova I , Zezulova A
Published: November 2021

Zeolites were synthetised from two types of metakaolin mixed with water glass and in some samples with water. The mixtures were autoclaved for 24 hours at 130°C. Autoclaved samples were ground to analytical fineness and tested by X-ray diffraction and differential thermal analysis. Polished samples embedded in epoxy resin were studied using of electron microprobe including BSE imaging and WDX analysis of chemical composition of zeolites. Samples with the highest zeolite content were studied by SEM. The obtained results showed that the dominant synthetised zeolite in autoclaved samples is mineral chemically close to chabazite, less phillipsite. Zeolite Na-P1, gmelinite and boggsite were also identified by XRD analyses. The total content of zeolites is up to 29 wt. % in the sample prepared from a mixture containing metakaolin MK1/sodium water glass/water in weight ratio 1.5/2.5/1. The Si/Al of synthetised zeolites varies between 2.1 and 3.2.
Optical properties of two-dimensional materials with tilted anisotropic Dirac cones: theoretical modeling with application to doped 8-Pmmn borophene
Authors: Margulis Vl A , Muryumin E E
Published: November 2021

The optical reflection, transmission and absorption properties of borophene, a newly discovered two-dimensional material with tilted anisotropic Dirac cones, are explored within a simple electronic band structure model of 8-Pmmn borophene, proposed by Zabolotskiy and Lozovik (2016 Phys. Rev. B 94 165403). It is assumed that the borophene layer is deposited on a dielectric substrate, such as Al2O3, and that the borophene’s electron density is controlled by an external gate voltage. The reflectance, transmittance and absorbance of the borophene layer, the conduction band of which is filled with electrons up to the Fermi level, are calculated against the frequency of the incident radiation, as well as on the angle of its incidence on the layer. Considered are the two principal cases of the incident radiation polarization either parallel to or normal to the plane of incidence. We reveal that the optical characteristics of 8-Pmmn borophene are distinctly different for the above two cases at all angles of radiation incidence, excepting the grazing incidence, for which the borophene layer is found to behave like a mirror regardless of the wave polarization. The results obtained indicate the possibility of visualizing the borophene layer deposited on a dielectric substrate by observing the minimum reflectivity of this layer at a certain angle incidence (called the quasi-Brewster angle) of the p-polarized radiation, which may differ by a value of about ten degrees from the Brewster angle of the substrate.
Second harmonic generation from tetraphenylethylene functionalized graphdiyne
Authors: Liu Chao , Cheng Puxin , Shi Rongchao , Ge Fei , Han Xiao , Qi Siming , Li Geng , Xu Jialiang
Published: November 2021

The nonlinear optical (NLO) properties of two-dimensional (2D) layered materials have received extensive attention for their promising application prospects in the field of optoelectronics. Among these materials, 2D carbon materials have been pushed to the research hotspot thanks to their unique chemical and electronic structures. However, the exploration of second harmonic generation is currently limited to sp2 hybridized 2D carbon materials, while the research on multi-hybridized carbon atomic materials is relatively rare. Here, we report the observation of optical second harmonic from tetraphenylethylene-graphdiyne (TPE-GDY), a fully conjugated fluorescent 2D material composed of sp and sp2 hybridized carbon atoms based on the TPE unit. TPE-GDY is mixed with polyvinylpyrrolidone (PVP) to prepare TPE-GDY/PVP nanocomposite films, which further improves the stability of TPE-GDY. Cotton effect and favorable SHG response have been observed from these composite films. Our research enriches the material system in the field of NLO effects and opens up broad prospects for functional and potential applications of 2D graphdiyne materials.
Reliability of spin-to-charge conversion measurements in graphene-based lateral spin valves
Authors: Safeer C K , Herling Franz , Choi Won Young , Ontoso Nerea , Ingla-Aynés Josep , Hueso Luis E , Casanova Fèlix
Published: November 2021

Understanding spin physics in graphene is crucial for developing future two-dimensional spintronic devices. Recent studies show that efficient spin-to-charge conversions (SCCs) via either the inverse spin Hall effect or the inverse Rashba–Edelstein effect (IREE) can be achieved in graphene by proximity with an adjacent spin–orbit coupling (SOC) material. Lateral spin valve devices, made up of a graphene Hall bar and ferromagnets, are best suited for such studies. Here, we report that signals mimicking the IREE can be measured in pristine graphene possessing negligible SOC, confirming that these signals are unrelated to SCC. We identify either the anomalous Hall effect in the ferromagnet or the ordinary Hall effect in graphene induced by stray fields as the possible sources of this artefact. By quantitatively comparing these options with finite-element-method simulations, we conclude the latter better explains our results. Our study deepens the understanding of SCC measurement schemes in graphene, which should be taken into account when designing future experiments.
Preparation and corrosion resistance properties of duplex stainless steel (00Cr22Ni6MnMoCu)
Authors: Bao Chonggao , Zhang Chong
Published: November 2021

In the present paper, a new kind of duplex stainless steel (DSS, 00Cr22Ni6MnMoCu) was prepared. Cr30 was chosen as a comparison of microstructures and mechanical properties with 00Cr22Ni6MnMoCu. Corrosion tests with 3.5% NaCl solution and electrolytic solution for 00Cr22Ni6MnMoCu were carried out to analyze the corrosion pattern of test materials. It can be concluded that: (1) Austenitic and ferrite duplex stainless steel has an optimized phase distribution, high toughness and strength when the ratio of two-phase content is 1:1. (2) Corrosion tests show that the corrosion resistance of 00Cr22Ni6MnMoCu is 12 times compared to ferrite stainless steel Cr30. (3) Electrolytic corrosion tests show that for 00Cr22Ni6MnMoCu, the corrosion is caused by intergranular corrosion. For Cr30, it is mainly caused by pinholes. However, Cr30 has a poor corrosion resistance because of the presence of a large amount of carbides and their phase boundaries caused by the electric potential difference between the carbide and the matrix.
Effect of N on corrosion resistance of Fe-Cr-Ni-Mo-Mn alloy
Authors: Liu Hongyu , Wang Tao , Guo Xuefeng , Feng Feng , Su Yunhai
Published: November 2021

In order to develop the Fe-Cr-Ni-Mo-Mn-N corrosion resistant alloys, analyze the influence of nitrogen on the corrosion resistance of Fe-Cr-Ni-Mo-Mn alloy, adjust the N content in the alloy system, and Flux cored wires with different N content were prepared. They were surfaced on low carbon steel by MIG welding. The phase composition, microstructure and corrosion resistance of the cladding metal were analyzed to study the effect of N content on the structure and performance of the surfacing metal. The results show that the addition of nitrogen does not change the matrix structure (which is Fe-Ni-Cr austenite), but with the increase of nitrogen content, the precipitation of nitrides (Cr2(C,N) and BN)is accompanied; when the amount of nitrogen added reaches 1.0%, the corrosion resistance of the surfacing metal is the best. At this time, the self-corrosion current density is at least 1.569 × 10–9 mA cm−2 and the self-corrosion potential is at most −0.318 V. The addition of nitrogen can promote the formation of austenite and nitride, inhibit the appearance of carbides, avoid the phenomenon of poor Cr, and improve the corrosion resistance of the material.
Effect of twinning and Al–Nd phase on dynamic recrystallization in rolled Mg–Al–Zn–Nd alloy at the moderate strain rate
Authors: Cui Xiaoming , Wang Zhengguang , Yu Zhilei , Liu Fei , Zhao Xueping , Du Zhaoxin , Bai Pucun
Published: November 2021

The dynamic recrystallization of Mg–Al–Zn–Nd alloy during moderate strain rate rolling was studied using electron backscatter diffraction (EBSD) and an energy dispersive spectrometer (EDS). The results showed three kinds of twinnings produced in the alloy in the strain rate range of 4.2 s−1∼7.3 s−1, including

{
10

1
¯

2
}

extension twinning,

{
10

1
¯

1
}

contraction twinning, and

10

1
¯

1

−

{
10

1
¯

2
}

double twinning. The extension twinnings decreased gradually with the increase of strain rate. The dynamic recrystallization mechanisms during hot rolling under moderate strain rate conditions mainly include grain boundary nucleation, twinning nucleation, and secondary particle assistant nucleation. The dynamic recrystallization mechanism induced by twinning is mainly

10

1
¯

1

−

{
10

1
¯

2
}

double twinnings. In addition, the strain value near the Al–Nd phase and grain boundary is higher than in grain. The Al–Nd particles in Mg–Al–Zn–Nd alloy play an auxiliary nucleation effect on dynamic recrystallization during hot rolling deformation.
Clustering and enhanced classification using a hybrid quantum autoencoder
Authors: Srikumar Maiyuren , Hill Charles D , Hollenberg Lloyd C L
Published: November 2021

Quantum machine learning (QML) is a rapidly growing area of research at the intersection of classical machine learning and quantum information theory. One area of considerable interest is the use of QML to learn information contained within quantum states themselves. In this work, we propose a novel approach in which the extraction of information from quantum states is undertaken in a classical representational-space, obtained through the training of a hybrid quantum autoencoder (HQA). Hence, given a set of pure states, this variational QML algorithm learns to identify—and classically represent—their essential distinguishing characteristics, subsequently giving rise to a new paradigm for clustering and semi-supervised classification. The analysis and employment of the HQA model are presented in the context of amplitude encoded states—which in principle can be extended to arbitrary states for the analysis of structure in non-trivial quantum data sets.
Intracorporeal versus extracorporeal anastomosis in laparoscopic right colectomy: updated meta-analysis of randomized controlled trials
Authors: Zhang Hongyu , Sun Nan , Fu Yang , Zhao Chunlin
Published: November 2021

Background

Selection of intracorporeal anastomosis (IA) or extracorporeal anastomosis (EA) in laparoscopic right colectomy (LRC) remains controversial. This meta-analysis aimed to evaluate the effectiveness and safety of IA compared with EA in LRC patients.

Methods

Literature was searched systematically for randomized controlled trials (RCTs) that compared IA with EA in LRC patients until May 2021. The eligible studies for risk of bias were assessed using the Cochrane Risk of Bias Tool. Data were extracted and analysed for the following outcomes of interest: operative time, length of incision, nodal harvest, bowel function recovery, postoperative pain, postoperative complications (wound infection, anastomotic leak, ileus, obstruction, reoperation), death at 30 days, duration of hospital stay and 30-day readmission.

Results

Five RCTs, including a total of 559 patients, were eligible for meta-analysis. All of the trials reported adequate random sequence generation and allocation concealment. There were significantly better outcomes in the IA group than in the EA group in time to first flatus (mean difference (MD) −0.71 (95 per cent c.i. −1.12 to −0.31), P = 0.0005), time to first passage of stool (MD −0.53 (95 per cent c.i. −0.69 to −0.37), P < 0.00001), visual analogue scale of pain on postoperative day (POD) 3 (MD −0.76 (95 per cent c.i. −1.23 to −0.28), P = 0.002), POD 4 (MD −0.83 (95 per cent c.i. −1.46 to −0.20), P = 0.01), POD 5 (MD −0.60 (95 per cent c.i. −0.95 to −0.25), P = 0.0007), length of incision (MD −1.52 (95 per cent c.i. −2.30 to −0.74), P = 0.0001) and wound infection (relative risk 0.46 (95 per cent c.i. 0.23 to 0.91), P = 0.02). However, there were no statistically significant differences between the two groups in duration of hospital stay (P = 0.47), operative time (P = 0.07), number of lymph nodes harvested (P = 0.70), anastomotic leak (P = 0.88), postoperative ileus (P = 0.48), bleeding (P = 0.15), bowel obstruction (P = 0.24), reoperation (P = 0.34), readmission within 30 days (P = 0.26), and death (P = 0.70).

Conclusion

Compared with EA, IA shows a faster recovery of bowel function with fewer wound infections.
How Can Progress Toward Ending the Human Immunodeficiency Virus Epidemic in the United States Be Monitored?
Authors: Mitchell Kate M , Maheu-Giroux Mathieu , Dimitrov Dobromir , Moore Mia , Hughes James P , Donnell Deborah , Beyrer Chris , El-Sadr Wafaa M , Cohen Myron S , Boily Marie Claude
Published: November 2021

The plan for Ending the HIV (human immunodeficiency virus) Epidemic (EHE) in the United States aims to reduce new infections by 75% by 2025 and by 90% by 2030. For EHE to be successful, it is important to accurately measure changes in numbers of new HIV infections after 5 and 10 years (to determine whether the EHE goals have been achieved) but also over shorter timescales (to monitor progress and intensify prevention efforts if required). In this viewpoint, we aim to demonstrate why the method used to monitor progress toward the EHE goals must be carefully considered. We briefly describe and discuss different methods to estimate numbers of new HIV infections based on longitudinal cohort studies, cross-sectional incidence surveys, and routine surveillance data. We particularly focus on identifying conditions under which unadjusted and adjusted estimates based on routine surveillance data can be used to estimate changes in new HIV infections.
Five-year outcomes in trials comparing transcatheter aortic valve implantation versus surgical aortic valve replacement: a pooled meta-analysis of reconstructed time-to-event data
Authors: Barili Fabio , Freemantle Nicholas , Musumeci Francesco , Martin Barbara , Anselmi Amedeo , Rinaldi Mauro , Kaul Sanjay , Rodriguez-Roda Jorge , Di Mauro Michele , Folliguet Thierry , Verhoye Jean-Philippe , Sousa-Uva Miguel , Parolari Alessandro ,   the Latin European Alliance of CardioVascular Surgical Societies (LEACSS) and with the endorsement of the Latin American Association of Cardiac and Endovascular Surgery (LACES), LEACSS members are the Italian Society of Cardiac Surgery (FB FM MR MdM AP), the Portuguese Society of Cardiac Surgery (MSU), the French Society of Cardiac Surgery (JFV, AA) and the Spanish Society of Cardiac Surgery (JRR) Institutions
Published: November 2021

OBJECTIVES

The incidence of outcomes in trials comparing transcatheter aortic valve implantation (TAVI) and surgical aortic valve replacement (SAVR) is expected to be different in the short and long term. We planned a meta-analysis of reconstructed time-to-event data from trials comparing TAVI and SAVR to evaluate their time-varying effects on outcomes.

METHODS

We performed a systematic review of the literature from January 2007 through September 2021 on Medline, Embase, the Cochrane Central Register of Controlled Trials and specialistic websites, including randomized trials with allocation to TAVI or SAVR that reported at least 1-year follow-up and that graphed Kaplan–Meier curves of end points. The comparisons were done with grouped frailty Cox models in a landmark framework and fully parametric models.

RESULTS

Seven trials were included (7770 participants). TAVI showed a lower incidence of the composite of death or stroke in the first 6 months [risk-stratified hazard ratio (HR) 0.66, 95% confidence interval (CI) 0.56–0.77, P-value <0.001], with an HR reversal after 24 months favouring SAVR (risk-stratified HR 1.25; 95% CI 1.08–1.46; P-value 0.003). These outcomes were confirmed for all-cause death (risk-stratified HR after 24 months 1.18; 95% CI 1.03–1.35; P-value 0.01). TAVI was also associated with an increased incidence of rehospitalization after 6 months (risk-stratified HR 1.42; 95% CI 1.06–1.91; P-value 0.018) that got worse after 24 months (risk-stratified HR 1.67; 95% CI 1.24–2.24; P-value <0.001).

CONCLUSIONS

Although it could appear that there is no difference between TAVI and SAVR in the 5-year cumulative results, TAVI shows a strong protective effect in the short term that runs out after 1 year. TAVI becomes a risk factor for all-cause mortality and the composite end point after 24 months and for rehospitalization after 6 months.
What makes Komagataella phaffii non-conventional?
Authors: Ata Özge , Ergün Burcu Gündüz , Fickers Patrick , Heistinger Lina , Mattanovich Diethard , Rebnegger Corinna , Gasser Brigitte
Published: November 2021

The important industrial protein production host Komagataella phaffii (syn Pichia pastoris) is classified as a non-conventional yeast. But what exactly makes K. phaffii non-conventional? In this review, we set out to address the main differences to the ‘conventional’ yeast Saccharomyces cerevisiae, but also pinpoint differences to other non-conventional yeasts used in biotechnology. Apart from its methylotrophic lifestyle, K. phaffii is a Crabtree-negative yeast species. But even within the methylotrophs, K. phaffii possesses distinct regulatory features such as glycerol-repression of the methanol-utilization pathway or the lack of nitrate assimilation. Rewiring of the transcriptional networks regulating carbon (and nitrogen) source utilization clearly contributes to our understanding of genetic events occurring during evolution of yeast species. The mechanisms of mating-type switching and the triggers of morphogenic phenotypes represent further examples for how K. phaffii is distinguished from the model yeast S. cerevisiae. With respect to heterologous protein production, K. phaffii features high secretory capacity but secretes only low amounts of endogenous proteins. Different to S. cerevisiae, the Golgi apparatus of K. phaffii is stacked like in mammals. While it is tempting to speculate that Golgi architecture is correlated to the high secretion levels or the different N-glycan structures observed in K. phaffii, there is recent evidence against this. We conclude that K. phaffii is a yeast with unique features that has a lot of potential to explore both fundamental research questions and industrial applications.
Regularizing linear inverse problems under unknown non-Gaussian white noise allowing repeated measurements
Authors: Harrach Bastian , Jahn Tim , Potthast Roland
Published: November 2021

We deal with the solution of a generic linear inverse problem in the Hilbert space setting. The exact right-hand side is unknown and only accessible through discretized measurements corrupted by white noise with unknown arbitrary distribution. The measuring process can be repeated, which allows to reduce and estimate the measurement error through averaging. We show convergence against the true solution of the infinite-dimensional problem for a priori and a posteriori regularization schemes as the number of measurements and the dimension of the discretization tend to infinity under natural and easily verifiable conditions for the discretization.
SAT: a Surrogate-Assisted Two-wave case boosting sampling method, with application to EHR-based association studies
Authors: Liu Xiaokang , Chubak Jessica , Hubbard Rebecca A , Chen Yong
Published: November 2021

Objectives

Electronic health records (EHRs) enable investigation of the association between phenotypes and risk factors. However, studies solely relying on potentially error-prone EHR-derived phenotypes (ie, surrogates) are subject to bias. Analyses of low prevalence phenotypes may also suffer from poor efficiency. Existing methods typically focus on one of these issues but seldom address both. This study aims to simultaneously address both issues by developing new sampling methods to select an optimal subsample to collect gold standard phenotypes for improving the accuracy of association estimation.

Materials and Methods

We develop a surrogate-assisted two-wave (SAT) sampling method, where a surrogate-guided sampling (SGS) procedure and a modified optimal subsampling procedure motivated from A-optimality criterion (OSMAC) are employed sequentially, to select a subsample for outcome validation through manual chart review subject to budget constraints. A model is then fitted based on the subsample with the true phenotypes. Simulation studies and an application to an EHR dataset of breast cancer survivors are conducted to demonstrate the effectiveness of SAT.

Results

We found that the subsample selected with the proposed method contains informative observations that effectively reduce the mean squared error of the resultant estimator of the association.

Conclusions

The proposed approach can handle the problem brought by the rarity of cases and misclassification of the surrogate in phenotype-absent EHR-based association studies. With a well-behaved surrogate, SAT successfully boosts the case prevalence in the subsample and improves the efficiency of estimation.
Validated Spectrophotometric Methods for Simultaneous Determination of Atorvastatin Calcium and Olmesartan Medoxomil in Their Pharmaceutical Formulation
Authors: Kamal Amira H , Hammad Sherin F , Marie Aya A
Published: November 2021

Background

Few spectrophotometric methods have been developed for the simultaneous determination of atorvastatin calcium (ATO) and olmesartan medoxomil (OLM).

Objective

This work aimed to develop and validate five simple spectrophotometric methods for the simultaneous estimation of ATO and OLM in their tablet form.

Methods

Method I applied the area under curve (AUC) based on the measurement of areas between 241 and 261 nm for ATO, and 248 and 263 nm for OLM. Method II applied second derivative spectrophotometry where the analytical amplitudes at 246.5 and 235 nm were chosen for the estimation of ATO and OLM, respectively. Method III applied the ratio difference (RD) method based on the measurement of amplitude difference (ΔP) within ratio spectra; ΔP (240–260 nm) was directly related to ATO concentration, and ΔP (262–240 nm) was directly related to OLM concentration. Method IV depended on the absorbance ratio method in which the wavelength at the iso-absorptive point (λISP) and the maximum absorbance wavelength (λmax), 277 and 255.5 nm, respectively, were used to calculate OLM concentration, while ATO concentration was determined from the zero-order UV spectra at 300 nm. Method V utilized a dual wavelength (DW) technique where ΔA between 247.5 and 262 nm was directly related to ATO concentration, and ΔA between 216 and 238 nm was directly related to OLM concentration.

Results

The results of the assays indicated good mean % recovery ± SD as well as good agreement with the reported method.

Conclusion

Five simple and rapid spectrophotometric methods were developed, validated, and successfully applied for simultaneous estimation of ATO and OLM tablets.

Highlights

None of the developed methods has previously been reported for simultaneous determination of ATO and OLM.
HPLC–MS Analysis of Four Potential Genotoxic Impurities in Alogliptin Pharmaceutical Materials
Authors: Al-Sabti Bashar , Harbali Jehad
Published: November 2021

Background

Pyridine, 3-aminopyridine, 4-dimethylaminopyridine, and N, N-dimethylamine are reactive bases that may be used in the preparation of the pharmaceutical ingredient alogliptin (ALO). They are considered as potentially genotoxic impurities (PGIs) since they contain electrophilic functional groups. Therefore, they should be monitored at the allowed limits in ALO.

Objective

The aim of this study was to develop a novel liquid chromatography–mass spectrometry (LC–MS) method to estimate quantities of pyridine, 3-aminopyridine, 4-dimethylaminopyridine, and N, N-dimethylaniline impurities in ALO drug material.

Methods

The separation was performed on Kromasil CN (250 mm × 3.9 mm, 3.5 µm) column in reversed phase mode. The mobile phase was a mixture of water-methanol (55:45, v/v) containing 2.5 mM ammonium acetate and 0.1% formic acid. Impurities were detected by MS in selected ion monitoring mode at m/z = 80, 95, 122, and 123 for pyridine, 3-aminopyridine, N, N-dimethylaniline, and 4-dimethylaminopyridine, respectively. The flow rate of the method was 0.5 mL/min.

Results

The sensitivity of the method was excellent at levels much less than the allowed limits. The method had excellent linearity in the concentration ranges of Quantitation Limit (QL)-150% of allowed limits and coefficients of determination were above 0.9990. The recovery ratios were in the range of 93.56–110.28%.

Conclusion

Results showed good linearity, precision, accuracy, sensitivity, selectivity, robustness, and solution stability. The studied method was applied to test two samples of raw materials and one sample of tablets.

Highlights

The method discussed here could be very useful for controlling potentially genotoxic impurities (PGIs) levels in ALO during its synthesis, and for QC testing of ALO raw materials before using them in the preparation of pharmaceutical products.
Experiments on Multiple Requests for Consent to Data Linkage in Surveys
Authors: Walzenbach Sandra , Burton Jonathan , Couper Mick P , Crossley Thomas F , JÄckle Annette
Published: November 2021

It is increasingly common for researchers to link survey data to administrative data. If several administrative data sources are of interest, respondents are required to give consent to each of them, meaning that multiple consent questions have to be included in one survey. Existing literature suggests that individual consent varies widely between data sources and over time, but little is known about how respondents process multiple consent requests in a single survey. Using an online access panel in Great Britain, we conducted a set of experiments in two surveys to explore multiple consent requests (covering five domains or data sources). In the first study, we experimentally varied the format of the request, testing three versions: (1) a sequence of pages (with one response per domain), (2) all five requests on the same page (with one response per domain), and (3) a single request (with one joint request covering all five domains). We also varied the order of the domains. We find that average consent rates do not differ by format, but asking a less-sensitive or easier-to-comply request first yields slightly higher average consent rates than asking a more sensitive request first. We repeated the order experiment in a second study, using an independent sample from the same panel, and adding two more order conditions. We find average consent rates are not affected much by order, but the consent to individual domains is affected by order. However, we fail to replicate the pattern of consents found in the first study. We conclude that the order in which multiple consent requests are asked does matter, but in complicated ways that depend on the particular outcomes in which one is interested. Objective knowledge and subjective comprehension of the consent process, and confidence in the decision are largely unaffected by format or order.
The return of the spin period in DW Cnc and evidence of new high state outbursts
Authors: Duffy C , Ramsay G , Steeghs D , Kennedy M R , West R G , Wheatley P J , Dhillon V S , Ackley K , Dyer M J , Galloway D K , Gill S , Acton J S , Burleigh M R , Casewell S L , Goad M R , Henderson B A , Tilbrook R H , Strøm P A , Anderson D R
Published: November 2021

DW Cnc is an intermediate polar which has previously been observed in both high and low states. Observations of the high state of DW Cnc have previously revealed a spin period at ∼38.6 min, however, observations from the 2018 to 2019 low state showed no evidence of the spin period. We present results from our analysis of 12 s cadence photometric data collected by Next Generation Transit Survey of DW Cnc during the high state which began in 2019. Following the previously reported suppression of the spin period signal, we identify the return of this signal during the high state, consistent with previous observations of it. We identify this as the restarting of accretion during the high state. We further identified three short outbursts lasting ∼1 d in DW Cnc with a mean recurrence time of ∼60 d and an amplitude of ∼1 mag. These are the first outbursts identified in DW Cnc since 2008. Due to the short nature of these events, we identify them not as a result of accretion instabilities but instead either from instabilities originating from the interaction of the magnetorotational instability in the accretion disc and the magnetic field generated by the white dwarf or the result of magnetic gating.