bluuebunny/crossref_metadata_2025 huggingface dataset:
A projection scheme for Navier‐Stokes with variable viscosity and natural boundary condition
Authors: Plasman L. , Deteix J. , Yakoubi D.
Published: May 2020

Combiningthe Navier‐Stokes systems with Neumann (or natural) boundary condition to characterize a fluid flow is frequent. The popular projection (or pressure correction) methods inspired by Chorin and Temam are not well adapted to such boundary condition, which translate in loss of accuracy. If some alternative projection methods have been proposed to reduce the accuracy loss due to the Neumann condition in case of Newtonian fluids, little has been proposed for generalized Newtonian fluids. In this work, we propose two methods derived from the incremental pressure correction projection that can be used for fluids with inhomogeneous or variable viscosity with natural boundary condition. Both time and space accuracy of the methods will be illustrated using a manufactured solution.
A higher order numerical scheme for generalized fractional diffusion equations
Authors: Ding Qinxu , Wong Patricia J. Y.
Published: May 2020

In this article, we develop a higher order approximation for the generalized fractional derivative that includes a scale function z(t) and a weight function w(t). This is then used to solve a generalized fractional diffusion problem numerically. The stability and convergence analysis of the numerical scheme are conducted by the energy method. It is proven that the temporal convergence order is 3 and this is the best result to date. Finally, we present four examples to confirm the theoretical results.
Adaptive mesh refinement for simulating fluid‐structure interaction using a sharp interface immersed boundary method
Authors: Wang Zhuo , Du Lin , Sun Xiaofeng
Published: May 2020

In this article, adaptive mesh refinement (AMR) is performed to simulate flow around both stationary and moving boundaries. The finite‐difference approach is applied along with a sharp interface immersed boundary (IB) method. The Lagrangian polynomial is employed to facilitate the interpolation from a coarse to a fine grid level, while a weighted‐average formula is used to transfer variables inversely. To save memory, the finest grid is only generated in the local areas close to the wall boundary, and the mesh is dynamically reconstructed based on the location of the wall boundary. The Navier‐Stokes equations are numerically solved through the second‐order central difference scheme in space and the third‐order Runge‐Kutta time integration. Flow around a circular cylinder rotating in a square domain is firstly simulated to examine the accuracy and convergence rate. Then three cases are investigated to test the validity of the present method: flow past a stationary circular cylinder at low Reynolds numbers, flow past a forced oscillating circular cylinder in the transverse direction at various frequencies, and a free circular cylinder subjected to vortex‐induced vibration in two degrees of freedom. Computational results agree well with these in the literature and the flow fields are smooth around the interface of different refinement levels. The effect of refinement level has also been evaluated. In addition, a study for the computational efficiency shows that the AMR approach is helpful to reduce the total node number and speed up the time integration, which could prompt the application of the IB method when a great near‐wall spatial resolution is required.
Uniformly convergent numerical method for singularly perturbed convection‐diffusion type problems with nonlocal boundary condition
Authors: Debela Habtamu Garoma , Duressa Gemechis File
Published: May 2020

In this article, we consider a class of singularly perturbed differential equations of convection‐diffusion type with nonlocal boundary conditions. A uniformly convergent numerical method is constructed via nonstandard finite difference and numerical integration methods to solve the problem. The nonlocal boundary condition is treated using numerical integration techniques. Maximum absolute errors and rates of convergence for different values of perturbation parameter and mesh sizes are tabulated for the numerical example considered. The method is shown to be ϵ‐uniformly convergent.
L1‐type smoothness indicators based weighted essentially nonoscillatory scheme for Hamilton‐Jacobi equations
Authors: Rathan Samala
Published: May 2020

This article presents an improved fifth‐order finite difference weighted essentially nonoscillatory (WENO) scheme to solve Hamilton‐Jacobi equations. A new type of nonlinear weights is introduced with the construction of local smoothness indicators on each local stencil that are measured with the help of generalized undivided differences in L1‐norm. A novel global smoothness measurement is also constructed with the help of local measurements from its linear combination. Numerical experiments are conducted in one‐ and two‐dimensions to demonstrate the performance enhancement, resolution power, numerical accuracy for the proposed scheme, and compared it with the classical WENO scheme.
Political risks and foreign direct investments by multinational corporations: A reference point approach
Authors: Yasuda Naoki , Kotabe Masaaki
Published: May 2020

Research Summary

The purpose of this study is to develop a behavioral framework for management decision‐making under bounded rationality to analyze foreign direct investments and political risks in host countries. This study shows that managers construct reference points on political risks and assess actual political risks in host countries relative to these reference points. This study considers that the political risk reference point is a mental map made up of (a) perceived political risks in host countries where multinational corporations (MNCs) operate and (b) home country political risks. We find that MNCs interpret political risks in host countries as opportunities (threats) if the political risks are below (above) their reference points. Our study provides a significant contribution to the literature on microfoundations of location strategy.

Managerial Summary

Prior empirical studies have found both positive and negative effects of political risks on MNCs' investments. This study develops a behavioral framework for MNCs' boundedly rational decision‐making in political risk assessment. Characterizing political risks in host countries by the concept of a political risk reference point resolves the contradictory findings in the literature. Using data from the global mining industry, we find that MNCs interpret political risks in host countries as opportunities (threats) if the political risks are below (above) their PRRPs. We also show that the other competing companies' reference points do not have significant effects on MNCs' investment decisions. These findings offer managerial implications because they help managers predict competitors' actions.
Supplier evolution in global value chains and the new brand game from an attention‐based view
Authors: Lechner Christian , Lorenzoni Gianni , Guercini Simone , Gueguen Gaël
Published: May 2020

Research Summary

Suppliers from emerging economies have been particularly active in acquiring brands from advanced economies. We analyze changes in the global value chain (GVC) of the sports shoe industry and show how hollowing out the asset bases of brand‐holding firms through increasing outsourcing has enabled the emergence of rising power firms, as well as a new brand game and a market for brands. These developments in the GVC might be a future challenge for traditional brand‐holding lead firms. We show that managers focused on branding and distribution issues were myopic towards the strategic initiatives of suppliers. Managers need to pay attention to the potential long‐term consequences of outsourcing and offshoring activities, as suppliers could become competitors or acquirers of their order‐giving firms, leading to the question: Are we approaching a state of dual GVC leadership, or do lead firms risk being kicked out by their suppliers?

Managerial Summary

We explore the emergence of rising power firms from the peripheries of GVCs. An increasing number of major brand‐holding companies from traditionally industrialized economies have been acquired by suppliers from newly industrialized economies due to some fundamental changes. First, the emergence of a market for brands makes brands more volatile. Second, continuous outsourcing and hollowing‐out of the lead firm's asset base has reduced their ability to control the GVC. Through a longitudinal case study analysis, by adopting an attention‐based view, we investigate the behavior of the traditional lead firms. Lead firms were not only myopic to the activities of their suppliers, but their focus on downstream activities created increasing opportunity spaces upstream for rising power firms while weakening the defense capacity of brands.
A numerical investigation of bedrock groundwater recharge and exfiltration on soil mantled hillslopes
Authors: Gardner W. Payton , Jensco Kelsey , H. Hoylman Zachary , Livesay Robert , P. Maneta Marco
Published: May 2020

Here we use Richards Equation models of variably saturated soil and bedrock groundwater flow to investigate first‐order patterns of the coupling between soil and bedrock flow systems. We utilize a Monte Carlo sensitivity analysis to identify important hillslope parameters controlling bedrock recharge and then model the transient response of bedrock and soil flow to seasonal precipitation. Our results suggest that hillslopes can be divided into three conceptual zones of groundwater interaction, (a) the zone of lateral unsaturated soil moisture accumulation (upper portion of hillslope), (b) the zone of soil saturation and bedrock recharge (middle of hillslope) and (c) the zone of saturated‐soil lateral flow and bedrock groundwater exfiltration (bottom of hillslope). Zones of groundwater interaction expand upslope during periods of precipitation and drain downslope during dry periods. The amount of water partitioned to the bedrock groundwater system a can be predicted by the ratio of bedrock to soil saturated hydraulic conductivity across a variety of hillslope configurations. Our modelled processes are qualitatively consistent with observations of shallow subsurface saturation and groundwater fluctuation on hillslopes studied in our two experimental watersheds and support a conceptual model of tightly coupled shallow and deep subsurface circulation where groundwater recharge and discharge continuously stores and releases water from longer residence time storage.
Land use change effects on catchment streamflow response in a humid tropical montane cloud forest region, central Veracruz, Mexico
Authors: López‐Ramírez Sergio M. , Sáenz Leonardo , Mayer Alex , Muñoz‐Villers Lyssette E. , Asbjornsen Heidi , Berry Z. Carter , Looker Nathaniel , Manson Robert , Gómez‐Aguilar León Rodrigo
Published: May 2020

Tropical montane cloud forests (TMCF) are recognized for their capacity to maintain high dry‐season baseflow and a host of other ecosystem services. Substantial areas of TMCF have been converted to pasture and crops such as coffee, while in other areas TCMF are recovering. However, little is known about the effects of this complex dynamic on catchment hydrology. We investigated the effect of land use on rainfall‐runoff response in five neighbouring headwater micro‐catchments in central Veracruz, Mexico, dominated by either mature TMCF (MF), young (20 year‐old) and intermediate (40 year‐old) naturally regenerating TMCF (YF and IF, respectively), shaded coffee (SC), and an intensively grazed pasture (IP). We used a 4‐year record of high‐resolution rainfall and streamflow (10 min) data collected from 2015 to 2019. These data were analysed via comparison of hydrologic metrics that summarize streamflow responses at various time scales and magnitudes. Results showed no statistical difference in the regulation capacity of high flows in the micro‐catchment with 20 years of natural regeneration, compared to the MF. In terms of baseflow sustenance, our results support the hypothesis that MF and IF better promote this hydrologic service than the other land uses. SC exhibited a high capacity to modulate peak flows comparable to that of MF, and an intermediate capacity to sustain baseflow, suggesting that the integrated functioning of this micro‐catchment was largely preserved. Finally, 40 years of intense pasture management was found to have degraded the soil hydraulic properties of IP; mainly, reducing its infiltration capacity, causing a fivefold greater peak flow response and a lower baseflow compared to MF.
Storm event sediment fingerprinting for temporal and spatial sediment source tracing
Authors: Vale Simon S. , Fuller Ian C. , Procter Jonathan N. , Basher Les R. , Dymond John R.
Published: May 2020

Sediment fingerprinting has been widely used to distinguish discrete sediment sources; however, application to intra‐storm sediment source variability has received relatively little focus despite the benefit being long recognized. In this investigation, sediment fingerprinting was applied to a 53‐hr storm event sampled hourly to determine sediment source dynamics throughout the event. Sediment sources were differentiated using 16 variables, and source contribution determined using Bayesian and Frequentist mixing models for comparison. Both models provided comparable source predictions for the dominant source estimates and the general temporal pattern. The Frequentist model appeared to exhibit some unreliable values coinciding with low GOF and attributed to inherent model structure. The Bayesian model showed higher uncertainty, likely due to the “process error” utilized associated with single sample mixtures. High variability in sediment source contribution was observed between hourly time steps; however, local smoothing reveals temporal trends during the event. A higher average proportion of mudstone is found in the falling limb (0.544) compared with the rising limb (0.464), and the reverse is observed for mountain range (0.218 vs. 0.283) and unconsolidated (0.073 vs. 0.055). In the initial hours of the storm, mudstone source contribution significantly drops, whereas mountain range and unconsolidated contributions peak. The SSC‐Q clockwise hysteresis indicates proximal sediment sources, suggesting the mudstone sediment is stored channel sediment and easily entrained. This sediment flushes through, coinciding with a drop as the distal mountain range and unconsolidated sources arrive to peak contribution. The wider Manawatū discharge and sediment load then arrive, delivering increasing levels of mudstone throughout the remainder of the event while mountain range sediment diminishes. Spatial representation of the sediment source contribution was derived from distributing sediment source loads to the spatial extent of the source material according to sub‐catchment sediment loads and was weighted according to slope. This provided an effective means to visualize the origin of the sediment and a better spatial interpretation of sediment fingerprinting results, which is typically limited by poor spatial resolution.
Forests and floods: Using field evidence to reconcile analysis methods
Authors: Bathurst James C. , Fahey Barry , Iroumé Andrés , Jones Julia
Published: May 2020

The extent to which forests, relative to shorter vegetation, mitigate flood peak discharges remains controversial and relatively poorly researched, with only a few significant field studies. Considering the effect purely of change of vegetation cover, peak flow magnitude comparisons for paired catchments have suggested that forests do not mitigate large floods, whereas flood frequency comparisons have shown that forests mitigate frequencies over all magnitudes of flood. This study investigates the apparent inconsistency using field‐based evidence from four contrasting field programmes at scales of 0.34–3.1 km2. Repeated patterns are identified that provide strong evidence of real effects with physical explanations. Magnitude and frequency comparisons are both relevant to the impact of forests on peak discharges but address different questions. Both can show a convergence of response between forested and grassland/logged states at the highest recorded flows but the associated return periods may be quite variable and are subject to estimation uncertainty. For low to moderate events, the forested catchments have a lower peak magnitude for a given frequency than the grassland/logged catchments. Depending on antecedent soil saturation, a given storm may nevertheless generate peak discharges of the same magnitude for both catchment states but these peaks will have different return periods. The effect purely of change in vegetation cover may be modified by additional forestry interventions, such as road networks and drainage ditches which, by effectively increasing the drainage density, may increase peak flows for all event magnitudes. For all the sites, forest cover substantially reduces annual runoff.
Loss of microRNA‐21 leads to profound stromal remodeling and short survival in K‐Ras‐driven mouse models of pancreatic cancer
Authors: Schipper Josh , Westerhuis Jennifer J. , Beddows Ian , Madaj Zach , Monsma David , Hostetter Galen , Kiupel Matti , Conejo‐Garcia Jose R. , Sempere Lorenzo F.
Published: May 2020

The microenvironment of pancreatic cancer adenocarcinoma (PDAC) is highly desmoplastic with distinct tumor‐restraining and tumor‐promoting fibroblast subpopulations. Re‐education rather than indiscriminate elimination of these fibroblasts has emerged as a new strategy for combination therapy. Here, we studied the effects of global loss of profibrotic noncoding regulatory microRNA‐21 (miR‐21) in K‐Ras‐driven p53‐deleted genetically engineered mouse models of PDAC. Strikingly, loss of miR‐21 accelerated tumor initiation via mucinous cystic neoplastic lesions and progression to locally advanced invasive carcinoma from which animals precipitously succumbed at an early age. The absence of tumor‐restraining myofibroblasts and a massive infiltrate of immune cells were salient phenotypic features of global miR‐21 loss. Stromal miR‐21 activity was required for induction of tumor‐restraining myofibroblasts in in vivo isograft transplantation experiments. Low miR‐21 expression negatively correlated with a fibroblast gene expression signature and positively with an immune cell gene expression signature in The Cancer Genome Atlas PDAC data set (n = 156) mirroring findings in the mouse models. Our results exposed an overall tumor‐suppressive function of miR‐21 in in vivo PDAC models. These results have important clinical implications for anti‐miR‐21‐based inhibitory therapeutic approaches under consideration for PDAC and other cancer types. Mechanistic dissection of the cell‐intrinsic role of miR‐21 in cancer‐associated fibroblasts and other cell types will be needed to inform best strategies for pharmacological modulation of miR‐21 activity to remodel the tumor microenvironment and enhance treatment response in PDAC.
U.S.‐Thai Consortium for the development of pharmacy education in Thailand: History, progress, and impact
Authors: Nathisuwan Surakit , Pattharachayakul Sutthiporn , Subongkot Suphat , Doungngern Thitima , Jones Sirada M. , Engle Janet P. , Lau Alan , Katz Michael D. , Moreton Julian Edward , Ryan Melody
Published: May 2020

In Thailand during the early 1990s, there was a need for an increased number of pharmacists and expansion of their knowledge and skills to address the need of the nation. Leaders of the Thai pharmacy education community at the time crafted a long‐term plan aiming to expand the pharmacy educator workforce at a national scale through the financial support of the Royal Thai Government. This led to the establishment of the United States‐Thai Consortium for the Development of Pharmacy Education in Thailand in 1994. The aim of the Consortium was to advance pharmacy education in Thailand through the support of leading U.S. pharmacy schools using both short‐term and long‐term trainings. Twenty plus years later, pharmacy education and practice in Thailand have changed dramatically. The number of faculties (schools) of pharmacy in Thailand has increased from 10 in 1993 to 19 in 2013. The ratio of pharmacists to population has decreased from 1:10532 in 1994 to 1:2261 in 2016. The professional pharmacy curriculum has changed from a 5‐year bachelor to a 6‐year Doctor of Pharmacy (Pharm.D.) degree. The role of Thai pharmacists has been endorsed by national health service initiatives and practice guidelines. Currently, 7 universities offer residency/fellowship programs. The 8 Thai founding institutions of the Consortium are now publishing over 500 papers in high‐quality international journals annually. In summary, pharmacy education, practice, and research in Thailand have improved dramatically through the U.S.‐Thai Pharmacy Consortium. This bi‐national model of knowledge and skill transfer may serve as an example for how a large‐scale international partnership can facilitate a rapid and positive transformation of pharmacy in a developing country. Local adjustment and adaptation are required to reflect national identity and to suit the local context.
Computed tomography for in vivo deep over‐1000 nm near‐infrared fluorescence imaging
Authors: Umezawa Masakazu , Sera Toshihiro , Yokota Hideo , Takematsu Maho , Morita Masahiko , Yeroslavsky Gil , Kamimura Masao , Soga Kohei
Published: May 2020

This study aims to develop a novel cross‐sectional imaging of fluorescence in over‐1000 nm near‐infrared (OTN‐NIR), which allows in vivo deep imaging, using computed tomography (CT) system. Cylindrical specimens of composite of OTN‐NIR fluorophore, NaGdF4 co‐doped with Yb3+ and Ho3+ (ex: 980 nm, em: 1150 nm), were embedded in cubic agar (10.5–12 mm) or in the peritoneal cavity of mice and placed on a rotatable stage. When the fluorescence from inside of the samples was serially captured from multiple angles, the images were disrupted by the reflection and refraction of emitted light on the sample‐air interface. Immersing the sample into water filled in a rectangular bath suppressed the disruption at the interface and successfully reconstructed the position and concentration of OTN‐NIR fluorophores on the cross‐sectional images using a CT technique. This is promising as a novel three‐dimensional imaging technique for OTN‐NIR fluorescent image projections of small animals captured from multiple angles.
Improved osteogenic differentiation of human amniotic mesenchymal stem cells on gradient nanostructured Ti surface
Authors: Wang Wei , Wang Zhenbo , Fu Yating , Dunne Nicholas , Liang Chen , Luo Xue , Liu Keda , Li Xiaoming , Pang Xining , Lu Ke
Published: May 2020

Titanium (Ti) and Ti‐based alloys are widely used in the manufacture of dental and orthopedic implants. However, how to improve their osteogenic differentiation ability is still a key issue to be resolved. In this study, gradient nanostructured surface (GNS) samples were prepared by surface mechanical grinding treatment, and coarse‐grained (CG) samples were obtained by recrystallization annealing, making sure that the two kinds of specimens had similar roughness. Then, human amniotic mesenchymal stem cells (hAMSCs) were cocultured with the two kinds of Ti to investigate the material effects on the cellular functions. The results demonstrated that the grains with size ~56 nm were formed on the surface of the GNS Ti, and the grain size gradually increases from the sample surface to interior. Compared to the CG samples, the GNS ones could make the adhesion effect of the hAMSCs better, and promote the cell proliferation and osteogenic differentiation more significantly, the preliminary mechanism of which might be due to their specific nanostructure, the thicker oxide layer formed on their surface and the enhanced hardness. Our results indicated that the gradient nanostructured Ti materials could enhance both osteogenic differentiation and mechanical properties, which may possess broader applications in bone tissue engineering and clinical implanting.
Productivity and scale‐up of poly(3‐hydroxybutyrate) production under different oxygen transfer conditions in cultures of Azotobacter vinelandii
Authors: Padilla‐Córdova Claudio , Mongili Beatrice , Contreras Pablo , Fino Debora , Tommasi Tonia , Díaz‐Barrera Alvaro
Published: May 2020

Background

Poly(3‐hydroxybutyrate) (PHB) is a polymer produced by Azotobacter vinelandii. The production of PHB in a bioreactor is affected by oxygen transfer conditions. The aim of this study was to evaluate PHB synthesis in extended batch of A. vinelandii, to obtain an operation curve (productivity versus oxygen transfer rate) and to scale up the bioprocess.

Results

PHB production by A. vinelandii under dinitrogen fixation was evaluated using an extended batch modality under different oxygen transfer rates (OTRs). Extended batch cultures were performed using different agitation rates (400, 600, 800 and 1000 rpm), which determined different OTRs in the cultures. Under the conditions evaluated, it was possible to establish an operation curve of PHB productivity at different OTRs, allowing for the establishment of the maximum productivity of PHB. The maximum PHB productivity obtained was 0.40 ± 0.05 g L−1 h−1, which was reached under an OTR of 22.1 ± 1.5 mmol L−1 h−1. Using the OTR as a criterion to scale up PHB production from 3 to 30 L, it was possible to obtain a similar PHB concentration (7.9 ± 0.0 g L−1) and volumetric productivity (0.43 ± 0.04 g L−1 h−1) on a 30 L scale.

Conclusions

The results lead to the conclusion that in extended cultures and under dinitrogen fixation in A. vinelandii cultures, the OTR value determines the maximum PHB productivity. This study provides evidence that the OTR is an adequate parameter as a criterion for the successful scaling up of PHB synthesis for the first time. © 2020 Society of Chemical Industry
Preparation of conjugated polyvinyl chloride/TiO2 nanotubes for Rhodamine B photocatalytic degradation under visible light
Authors: Bui Dai‐Phat , Huu Pham Huan , Minh Cao Thi , Van Pham Viet
Published: May 2020

BACKGROUND

Efficient and stable photocatalysts are essential for the removal of organic dyes in wastewater. Here, the nanocomposites of conjugated polyvinyl chloride supported on hydrothermally synthesized titanium dioxide nanotubes (cPVC/TNTs) were fabricated by a simple annealing process. Their photocatalytic ability and reaction mechanisms were also investigated via degrading Rhodamine B (RhB) under different conditions.

RESULTS

The functional groups, instinct characteristic bonding, crystallinity, and morphology were characterized by the Fourier‐transform infrared spectroscopy (FTIR), Raman spectroscopy, X‐ray diffraction (XRD), and transmission electron microscopy (TEM), respectively. These results confirmed the success of nanocomposites preparation. In addition, the band energy structure of materials was investigated by electrochemical analysis (ECA) and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). The band structure and photocatalytic experiments showed that the 10% cPVC/TNTs could work under visible light and degrade 90% of RhB, while cPVC and TNTs lack this performance. The vital role of both electrons and holes were confirmed with the evidence obtained from the trapping experiment.

CONCLUSION

The combination of cPVC and TNTs significantly improved photocatalytic performance and stability. Their properties and reaction mechanisms were detailly described to further other research. © 2020 Society of Chemical Industry
Biological cyanide removal from industrial wastewater by applying membrane bioreactors
Authors: Lintzos Loukas , Koumaki Elena , Mendrinou Panagiota , Chatzikonstantinou Kostas , Tzamtzis Nikolaos , Malamis Simos
Published: May 2020

BACKGROUND

This work investigates whether the membrane bioreactor (MBR) process can effectively treat industrial wastewater containing high cyanide concentrations; cyanide may inhibit the biological processes, rendering such processes inadequate. In this work, the changes in process performance and microbial activity under gradually increased free cyanide (CN−) concentrations (1,3 and 10 mgCN−L−1) were investigated in two pilot‐scale MBR configurations. The MBR systems consisted of two parallel operating lines: a single aerobic (MBR1) and an aerobic/anoxic (MBR2).

RESULTS

Cyanide removal was not adversely affected by the increase in cyanide concentration since removals up to 90% were obtained. Despite the inhibition that occurred, ammonia and organic carbon removal efficiency did not decrease, even at the highest cyanide concentration of 10 mgCN−L−1, and it remained high (>95%) in both systems. Nitrification (sAUR) was inhibited by 35%, 54%, and 64% in MBR1 and by 16%, 25%, and 36% in MBR2, with the addition of 1, 3, and 10 mgCN−L−1, respectively. The aerobic respiration (sOUR) was inhibited considerably less with an inhibition of 19%, 37%, and 45% in MBR1 and 9%, 16%, and 21% in MBR2. The biomass maintained under both aerobic and anoxic conditions (MBR2) was more tolerant to cyanide compared to the biomass that was acclimated under only aerobic conditions (MBR1).

CONCLUSION

At high cyanide load conditions, the MBR systems showed satisfactory removal of both cyanide and conventional pollutants despite the inhibition observed, indicating that MBR systems can successfully respond to the treatment of industrial wastewater that is heavily contaminated with cyanide. © 2020 Society of Chemical Industry
Strategic planning for chemicals and fuels bioconversion processes
Authors: Bonatsos Nikolaos , Moutousidi Eleni , Kookos Ioannis K
Published: May 2020

BACKGROUND

The huge industrial growth of recent decades has led to the production of significant amounts of by‐product streams. The appropriate use of these by‐product streams can offer benefits either socially, by producing high quality products, or environmentally, by avoiding the excessive use of natural resources and reducing their impact on natural ecosystems. Technology selection at a strategic level is among the most challenging problems in many areas of science and engineering.

RESULTS

A case study is considered, in which 300 kt year−1 of monosaccharides are assumed available to produce a spectrum of potential bio‐based products. In an optimal situation, all raw material is utilized for the production of bio‐succinic acid with a manufacturing cost of 522.3 M$ year−1, revenue of 747 M$ year−1 and a net present value (NPV) of M$1482.4. When less than 50% of the raw material can be utilized by any of the available technologies, the algorithm selects the simultaneous production of succinic acid and methyl‐ethyl‐ketone and the NPV is reduced to M$1360. Finally, when each technology cannot use more than 1/8 of the available raw material, five out the eight potential technologies are selected, which end up consuming 62.5% of the available raw material while the NPV is reduced significantly to M$497.

CONCLUSION

A novel and practically useful mathematical programming method, that can be used to assist in making decisions related to a long‐term planning of biotechnological production processes using renewable raw materials, is proposed in this work and its advantages are demonstrated through a large‐scale case study.
Long‐term virologic responses to antiretroviral therapy among HIV‐positive patients entering adherence clubs in Khayelitsha, Cape Town, South Africa: a longitudinal analysis
Authors: Kehoe Kathleen , Boulle Andrew , Tsondai Priscilla R , Euvrard Jonathan , Davies Mary Ann , Cornell Morna
Published: May 2020

Introduction

In South Africa, an estimated 4.6 million people were accessing antiretroviral therapy (ART) in 2018. As universal Test and Treat is implemented, these numbers will continue to increase. Given the need for lifelong care for millions of individuals, differentiated service delivery models for ART services such as adherence clubs (ACs) for stable patients are required. In this study, we describe long‐term virologic outcomes of patients who have ever entered ACs in Khayelitsha, Cape Town.

Methods

We included adult patients enrolled in ACs in Khayelitsha between January 2011 and December 2016 with a recorded viral load (VL) before enrolment. Risk factors for an elevated VL (VL >1000 copies/mL) and confirmed virologic failure (two consecutive VLs >1000 copies/mL one year apart) were estimated using Cox proportional hazards models. VL completeness over time was assessed.

Results

Overall, 8058 patients were included in the analysis, contributing 16,047 person‐years of follow‐up from AC entry (median follow‐up time 1.7 years, interquartile range [IQR]:0.9 to 2.9). At AC entry, 74% were female, 46% were aged between 35 and 44 years, and the median duration on ART was 4.8 years (IQR: 3.0 to 7.2). Among patients virologically suppressed at AC entry (n = 8058), 7136 (89%) had a subsequent VL test, of which 441 (6%) experienced an elevated VL (median time from AC entry 363 days, IQR: 170 to 728). Older age (adjusted hazard ratio [aHR] 0.64, 95% confidence interval [CI] 0.46 to 0.88), more recent year of AC entry (aHR 0.76, 95% CI 0.68 to 0.84) and higher CD4 count (aHR 0.67, 95% CI 0.54 to 0.84) were protective against experiencing an elevated VL. Among patients with an elevated VL, 52% (150/291) with a repeat VL test subsequently experienced confirmed virologic failure in a median time of 112 days (IQR: 56 to 168). Frequency of VL testing was constant over time (82 to 85%), with over 90% of patients remaining virologically suppressed.

Conclusions

This study demonstrates low prevalence of elevated VLs and confirmed virologic failure among patients who entered ACs. Although ACs were expanded rapidly, most patients were well monitored and remained stable, supporting the continued rollout of this model.
Stability assessment of levofloxacin in three different suspension vehicles
Authors: Tardif Véronique , Lepage Olivier , Friciu Mihaela , St‐Jean Isabelle , Forest Jean‐Marc , Leclair Grégoire , Roullin V. Gaëlle
Published: May 2020

Background

Levofloxacin is a broad‐spectrum antibiotic of the fluoroquinolone class used in the paediatric population to treat resistant bacterial infections. Because no commercial option exists, a stable liquid formulation of this antibiotic made with accessible vehicles would be useful.

Aim

The aim of this study was to develop and assess the stability of levofloxacin suspensions made from commercially available tablets and three different accessible vehicles.

Methods

Levofloxacin suspensions (50 mg/mL) were compounded using two different commercially available tablets (from Apotex; Toronto, ON, Canada and Sandoz; Boucherville, QC, Canada) and three different vehicles (Ora‐Blend, Oral‐Mix; Medisca, Saint‐Laurent, QC, Canada and Simple Syrup (SS); Laboratoire Atlas Inc., Anjou, QC, Canada). Suitable suspensions in Ora‐Blend and Oral‐Mix were stored at room temperature (25°C) as well as under refrigeration (5°C) in amber plastic bottles for 90 days. Suspensions made with SS were only stored at 25°C because of sugar crystallisation at 5°C. Suspension concentrations were assessed by HPLC.

Results

Suspensions using Apotex levofloxacin tablets produced unsuitable high‐foaming, phase‐separated, non‐homogeneous suspension products in all vehicles tested that were therefore not tested for stability. Levofloxacin suspensions prepared using Sandoz tablets remained chemically and physically stable for 3 months, with >96% recovery according to United States Pharmacopeia criteria (90%–110%) in all three vehicles.

Conclusion

The results show that the choice of generic levofloxacin tablets is important when preparing homogeneous suspensions. All three vehicles could be used to prepare levofloxacin suspensions using Sandoz tablets that were physically and chemically stable for 3 months.
Fabrication of all‐cellulose nanocomposites from corn stalk
Authors: Bian Hongxia , Tu Peng , Chen Jonathan Y
Published: May 2020

BACKGROUND

There is a need to help farmers and industries develop value‐added composite and nanocomposite materials from agricultural residuals. Cellulose nanofibers (CNFs) were made using a TEMPO oxidation method and celluloses were prepared by acid–base method and extracting method, which were all from corn stalk, an agricultural residual. The prepared celluloses were dissolved separately in dimethylacetamide/LiCl solvent and CNFs were added at 0.0%, 0.5%, 1.5% and 3.0% to form all‐cellulose nanocomposites, and then cast into films. Morphology, structure and properties of the nanocomposite films were characterized using atomic force microscopy, field emission scanning electron microscopy, thermogravimetric analysis, X‐ray diffraction and mechanical testing.

RESULTS

The all‐cellulose nanocomposite films with different cellulose matrices exhibited good optical transparency and layer structure. The all‐cellulose nanocomposite films with cellulose prepared by the extracting method (Composite E) exhibited a higher crystallinity, better thermal stability and higher mechanical strength compared to the all‐cellulose nanocomposite films with cellulose prepared by the acid–base method (Composite A).

CONCLUSIONS

The crystal structure of the all‐cellulose nanocomposite films indicated the coexistence of cellulose I and cellulose II. However, in contrast to Composite A, the diffraction intensity of cellulose I in Composite E was higher than that of cellulose II. This was another reason that the mechanical properties of Composite E were superior to those of Composite A. In addition, the mechanical properties of the all‐cellulose nanocomposite films were significantly different when the addition of CNFs reached 3.0% by weight, as indicated by a multiple‐range comparison. © 2020 Society of Chemical Industry
Development of a novel nano‐based detection card by electrospinning for rapid and sensitive analysis of pesticide residues
Authors: Zhai Meng‐Yu , Feng Kun , Hu Teng‐Gen , Zong Min‐Hua , Wu Hong
Published: May 2020

BACKGROUND

Increasing food safety awareness of consumers promotes the development of rapid and sensitive detection techniques for pesticide residues. In this study, a new type of rapid detection card for organophosphorus and carbamate pesticide residues was developed by electrospinning. The card involved enzyme fiber mat (EFM) and substrate fiber mat (SFM) which were prepared by mixing poly(vinyl alcohol) with acetylcholinesterase (AChE) and indolyl acetate (IA), respectively.

RESULTS

The mean diameter of fibers was 240 ± 53 nm for EFM and 387 ± 84 nm for SFM. Results of Fourier transform infrared and X‐ray photoelectron spectroscopies confirmed that AChE and IA were successfully encapsulated into the fibers. The minimum concentrations of AChE and IA for effective detection were 1 and 3 mg mL−1, respectively, and the optimal detection time was 15 min. The limits of detection for this card were 0.5 mg L−1 for omethoate, 1.5 mg L−1 for malathion, 0.1 mg L−1 for carbaryl and 0.02 mg L−1 for carbofuran. The detection card exhibited good storage stability and its activity could be maintained when stored at room temperature for at least 4 months. Additionally, the EFM can be reused three times.

CONCLUSIONS

The detection card obtained here was superior to a commercial card in detecting pesticide residues in real food samples. Hence, this electrospun detection card has potential for simple, rapid and sensitive analysis of pesticide residues. © 2020 Society of Chemical Industry
Functional compounds from olive pomace to obtain high‐added value foods – a review
Authors: Difonzo Graziana , Troilo Marica , Squeo Giacomo , Pasqualone Antonella , Caponio Francesco
Published: May 2020

Olive pomace, the solid by‐product from virgin olive oil extraction, constitutes a remarkable source of functional compounds and has been exploited by several authors to formulate high value‐added foods and, consequently, to foster the sustainability of the olive‐oil chain. In this framework, the aim of the present review was to summarize the results on the application of functional compounds from olive pomace in food products.

Phenolic‐rich extracts from olive pomace were added to vegetable oils, fish burgers, fermented milk, and in the edible coating of fruit, to take advantage of their antioxidant and antimicrobial effects. Olive pomace was also used directly in the formulation of pasta and baked goods, by exploiting polyunsaturated fatty acids, phenolic compounds, and dietary fiber to obtain high value‐added healthy foods and / or to extend their shelf‐life. With the same scope, olive pomace was also added to animal feeds, providing healthy, improved animal products. Different authors used olive pomace to produce biodegradable materials and / or active packaging able to increase the content of bioactive compounds and the oxidative stability of foods.

Overall, the results highlighted, in most cases, the effectiveness of the addition of olive pomace‐derived functional compounds in improving nutritional value, quality, and / or the shelf‐life of foods. However, the direct addition of olive pomace was found to be more challenging, especially due to alterations in the sensory and textural features of food. © 2020 Society of Chemical Industry
A novel approach to the characterization of old wheat (Triticum aestivum L.) varieties by complex rheological analysis
Authors: Bánfalvi Ágnes , Németh Renáta , Bagdi Attila , Gergely Szilveszter , Rakszegi Marianna , Bedő Zoltán , Láng László , Vida Gyula , Tömösközi Sándor
Published: May 2020

BACKGROUND

Lines of the internationally recognized old Hungarian Bánkúti 1201 variety are important genetic resources for breeding programmes. Their protein composition and gluten dependent technological traits have been comprehensively studied, however, little information is available about their carbohydrate dependent viscous properties. The aim of this work was to obtain comprehensive rheological characterization of all sublines of Bánkúti 1201 maintained at Martonvásár and to investigate their variability if the carbohydrate dependent viscous behaviour was also included in the analyses.

RESULTS

The majority of the lines reflected the famously good mixing quality of Bánkúti, however, much higher diversity of pasting behaviour was detected. Cluster analysis of the Mixolab data was performed resulting in four sample groups. Since several lines of similar mixing properties had significantly different pasting characteristics, it was assumed that classification was mainly based on the viscous properties. From each cluster two to three representative samples were selected for wider examination using conventional testing methods. These results also supported the higher variability of pasting behaviour of the lines, which can be critical for end product quality. The members of the second cluster can be highlighted due to their waxy wheat like behaviour.

CONCLUSIONS

Possible reasons for the great variability of pasting behaviour could be the compositional and structural differences of starch and other carbohydrates (e.g. arabinoxylans). Complex rheological characterization and study of molecular background can provide information about important traits from the point of view of technology and product development, which are unknown in the case of old wheat varieties and landraces. © 2020 Society of Chemical Industry
Metabolism and biological activity of α‐tocopherol derived from vitamin E‐enriched transgenic maize in broilers
Authors: Zhan Tengfei , Han Yunsheng , Tang Chaohua , Zhao Qingyu , Sun Dandan , Li Ying , Jia Xueting , Zhou Lingyun , Zhang Junmin
Published: May 2020

BACKGROUND

The aim of this study was to investigate the metabolism of α‐tocopherol derived from vitamin E‐enriched transgenic maize (VER) and its effects on antioxidant and immune functions in broilers aged 1–42 days. A total of 360 1‐day‐old male broilers were randomly divided into three groups containing six replicates with 20 broilers per replicate. The negative control (NC) group and the positive control (PC) group were given non‐GM maize and non‐GM maize plus exogenous vitamin E (VE), respectively, and the VER group was given VER, replacing the non‐GM maize given to the NC group. Between days 1 and 21 and days 22 and 42, VE levels were 4.38 and 4.63 mg kg−1 in the NC group, and 14.11 and 14.91 mg kg−1 in the PC and VER group, respectively.

RESULTS

The results showed that α‐tocopherol from both VER and additives increased α‐tocopherol transfer protein and cytochrome P450 concentrations. Serum α‐tocopherol and α‐tocopherylquinone levels of broilers in the PC and VER groups were also significantly higher than those in the NC group (P < 0.05). Compared with the NC group, broilers in both groups that received α‐tocopherol had reduced NF‐κB p65 concentrations, significantly decreased serum prostaglandin E2, interleukin‐6, malondialdehyde, and hydrogen peroxide levels (P < 0.05), and significantly increased glutathione, glutathione peroxidase, and total antioxidant capacity (P < 0.05).

CONCLUSION

In summary, both VER and non‐GM maize fortified with exogenous VE showed similar effects on broilers, indicating that the α‐tocopherol in VER has sufficient biological activity. © 2020 Society of Chemical Industry
Simultaneous and rapid determination of sesamin and sesamolin in sesame oils using excitation‐emission matrix fluorescence coupled with self‐weighted alternating trilinear decomposition
Authors: Liu Yan , Wu Qian , Xia Zhenzhen , Wu Yang , Li Yan , Gong Zhiyong
Published: May 2020

BACKGROUND

Sesamin and sesamolin are two typical and important lignans isolated from sesame oil. Various studies have shown the bioactivity, physiological activity, and potential health benefits of the two components. In this study, a rapid method for the simultaneous determination of sesamin and sesamolin in sesame oils was proposed. The excitation‐emission fluorescence spectra of the oils were obtained after a simple pretreatment, then self‐weighted alternating trilinear decomposition was used to extract the quantitative information from the very overlapping spectra.

RESULTS

It was found that reasonable quantification results could be obtained with the limits of detection for the two lignans. These limits were 0.05 mg/g and 0.24 mg/g, and the limits of quantitation were 0.14 mg/g and 0.74 mg/g, respectively. The average recoveries for sesamin and sesamolin were 99.05% and 94.97%.

CONCLUSION

The results indicate that, with simple sample pretreatment, the application for combining excitation‐emission fluorescence spectra and self‐weighted alternating trilinear decomposition can be a useful and sensitive tool for the determination of lignans in sesame oil. © 2020 Society of Chemical Industry
The effects of humic acid urea and polyaspartic acid urea on reducing nitrogen loss compared with urea
Authors: Shen Yuwen , Lin Haitao , Gao Wensheng , Li Mingli
Published: May 2020

BACKGROUND

The utilization rate of urea‐N in fertilizer plays a very important role in agricultural production and environmental protection. Humic acid urea (HAU) and polyaspartic acid urea (PAU) are two similar synergistic nitrogen fertilizers.

METHODS

Fourier‐transform infrared spectroscopy (FTIR), X‐ray powder diffraction (XRD) and carbon‐13‐nuclear magnetic resonance (13C‐NMR) were used to determine the loading of urea‐N into humic acid (HA) and polyaspartic acid (PA). Thermal stability and physical adsorption properties of HAU and PAU were assessed by thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) surface measurement. The soil incubation experiment was conducted to investigate the effects of HAU and PAU on nitrogen transformation and gaseous nitrogen loss compared with commercial urea.

RESULTS

Nitrogen transformation from HAU and PAU was slowed down compared with urea. After 90 days of incubation, HAU and PAU reduced the cumulative ammonia (NH3) volatilization (by 9.70% and 6.30%, respectively) and nitrous oxide (N2O) emission (by 40.48% and 43.00%, respectively) from soil compared with the urea‐alone treatment.

CONCLUSION

HAU and PAU could improve the nitrogen use efficiency. © 2020 Society of Chemical Industry