bluuebunny/crossref_metadata_2025 huggingface dataset:
Survival after the diagnosis of de novo malignancy in liver transplant recipients
Authors: Taborelli Martina , Piselli Pierluca , Ettorre Giuseppe Maria , Baccarani Umberto , Burra Patrizia , Lauro Augusto , Galatioto Laura , Rendina Maria , Shalaby Sarah , Petrara Raffaella , Nudo Francesco , Toti Luca , Fantola Giovanni , Cimaglia Claudia , Agresta Alessandro , Vennarecci Giovanni , Pinna Antonio Daniele , Gruttadauria Salvatore , Risaliti Andrea , Di Leo Alfredo , Rossi Massimo , Tisone Giuseppe , Zamboni Fausto , Serraino Diego ,   for the Italian Transplant and Cancer Cohort Study
Published: August 2018

In the setting of liver transplant (LT), the survival after the diagnosis of de novo malignancies (DNMs) has been poorly investigated. In this study, we assessed the impact of DNMs on survival of LT recipients as compared to corresponding LT recipients without DNM. A nested case–control study was conducted in a cohort of 2,818 LT recipients enrolled in nine Italian centres between 1985 and 2014. Cases were 244 LT recipients who developed DNMs after LT. For each case, two controls matched for gender, age, and year at transplant were selected by incidence density sampling among cohort members without DNM. The survival probabilities were estimated using the Kaplan–Meier method. Hazard ratios (HRs) of death and 95% confidence intervals (CIs) were estimated using Cox proportional hazard models. The all‐cancer 10‐year survival was 43% in cases versus 70% in controls (HR = 4.66; 95% CI: 3.17–6.85). Survival was impaired in cases for all the most frequent cancer types, including lung (HR = 37.13; 95% CI: 4.98–276.74), non‐Hodgkin lymphoma (HR = 6.57; 95% CI: 2.15–20.01), head and neck (HR = 4.65; 95% CI: 1.81–11.95), and colon‐rectum (HR = 3.61; 95% CI: 1.08–12.07). The survival gap was observed for both early and late mortality, although the effect was more pronounced in the first year after cancer diagnosis. No significant differences in survival emerged for Kaposi's sarcoma and nonmelanoma skin cancers. The survival gap herein quantified included a broad range of malignancies following LT and prompts close monitoring during the post‐transplant follow‐up to ensure early cancer diagnosis and to improve survival.
Alternative Conceptions and the Learning of Chemistry
Authors: Taber Keith S.
Published: August 2018

A great deal of research has indicated that teaching is rarely a matter of introducing learners to material that simply replaces previous ignorance, but is more often a matter of presenting ideas that are somewhat at odds with existing understanding. In subjects such as chemistry, learners at school and university come to their studies already holding misconceptions or ‘alternative conceptions’ of subject matter. This has implications for subsequent learning, and so for teaching. This article reviews a number of key issues: (i), the origins of these alternative conceptions; (ii), the nature of these ideas; and, (iii), how they influence learning of the chemistry curriculum. These issues are in turn significant for guidance on (a) how curriculum should be selected and sequenced, and (b) on the pedagogy likely to be most effective in teaching chemistry. A specific concern reported in chemistry education is that one source of alternative conceptions seems to be instruction itself.
The association between Helicobacter pylori seropositivity and low birthweight in a Sudanese maternity hospital
Authors: Mustafa Ahmed , Bilal Naser E. , Abass Awad‐Elkareem , Elhassan Elhassan M. , Adam Ishag
Published: August 2018

Objective

To investigate the association between Helicobacter pylori seropositivity and low birthweight (LBW).

Methods

The present case–control study was conducted at a Sudanese maternity hospital from September 1 to December 30, 2015. Patients who delivered single neonates with LBW (>500 g but <2500 g) and the subsequent singleton delivery with birthweight of 2500–4000 g were included. A questionnaire was used to collect medical and obstetric data. The presence of malarial parasites in peripheral, placental, and umbilical cord samples was investigated using blood films. The presence of H. pylori immunoglobulin G (IgG) in maternal and umbilical cord serum samples was determined by enzyme‐linked immunosorbent assay.

Results

The study included 87 patients in each of the LBW and control groups. Maternal serum tested positive for H. pylori IgG among 66 (75.9%) and 48 (55.2%) patients in the LBW and control groups (P=0.006); no malarial parasites were observed. Similarly, umbilical cord serum tested positive for H. pylori IgG among 66 (75.9%) and 34 (39.1%) patients in the LBW and control groups (P<0.001). Maternal H. pylori IgG seropositivity (OR 3.2, 95% CI 1.4–7.2; P=0.003) and umbilical cord H. pylori IgG seropositivity (OR 2.4, 95% confidence interval 2.1–10.2; P<0.001) were significantly associated with LBW.

Conclusion

Seropositivity for H. pylori IgG was associated with LBW.
The role of visual and physiological refuges in humic lakes: Effects of oxygen, light quantity, and spectral composition on daytime depth of chaoborids
Authors: Horppila Jukka , Liljendahl Anne , Estlander Satu , Nurminen Leena
Published: August 2018

To clarify the effect of brownification on the functioning of lake ecosystems, the utilization of daytime refuges by chaoborids was examined in two lakes having different water color. It was hypothesized that with high water color, oxygen concentration plays a smaller role for the behavior of chaoborids than with lower water color. It was also expected that the depth distribution of chaoborids is associated with light intensity at 680–700 nm. This could decrease their visibility to predators. In Lake Iso Valkjärvi with 50 mg L−1 Pt water color, chaoborids occurred below 5 m depth, where the oxygen concentration was 0.4 mg L−1. Supporting the first hypothesis, in Lake Majajärvi with 340 mg L−1 Pt color, the leading edge of the population was at 3 m with 3.5 mg L−1 oxygen concentration. In Majajärvi, chaoborids remained in a layer where planktivorous fish could feed, explained by the low light intensity that decreased the potential predation pressure of fish. In Iso Valkjärvi with higher light intensity, chaoborids inhabited only the layers where oxygen concentration was too low for fish. Supporting the second hypothesis, the intensity of 693 nm light in the two lakes was similar at the depth of the leading edge of the chaoborid population. This wavelength represents the wavelengths that chaoborids reflect most effectively and is beyond the sensitivity peak of their main predator perch. The results suggested that combined effects of oxygen and water color are potential explanatory mechanisms of the observed patterns in the behavior of chaoborids. The results thus suggested that along the worldwide brownification of lakes, the role of oxygen as a regulator of invertebrate predators may change. Because invertebrate predators are important components of lake food webs, such effects may be reflected to the whole ecosystem and further studies on the subject are encouraged.
Elucidating the role of (p)ppGpp in mycobacterial persistence against antibiotics
Authors: Bhaskar Ashima , De Piano Cyntia , Gelman Ekaterina , McKinney John D. , Dhar Neeraj
Published: August 2018

Bacterial persistence, the ability of bacteria to survive high concentrations of antibiotics for extended periods of time, is an important contributing factor to therapy failure and development of chronic and recurrent infections. Several recent studies have suggested that this persistence is mediated primarily by (p)ppGpp, through its interactions with toxin–antitoxin modules and polyphosphates. In this study, we address whether these key players play a role in mycobacterial persistence against antibiotics. We targeted these specific pathways in Mycobacterium smegmatis by constructing deletion strains of (p)ppGpp synthetase/hydrolase (relA), polyphosphate kinases (ppk1 and ppk2), exopolyphosphatases (ppx1 and ppx2), and the lon protease. None of these mutant strains exhibited altered levels of persisters against isoniazid and ciprofloxacin, when compared with wild‐type strain. Even under conditions in which the stringent response usually gets activated, these strains displayed wild‐type persister levels. Interestingly, we also found that unlike Escherichia coli, maintaining M. smegmatis in exponential phase by repeated passaging does not eliminate persisters suggesting that at least against the antibiotics tested, stationary‐phase dependent persisters (type I) are not the major contributors. Thus, our data demonstrate that multiple mechanisms of antibiotic persistence exist and that these vary widely among different bacterial species. © 2018 IUBMB Life, 70(9):836–844, 2018
Detection of HCV genome in peripheral blood mononuclear cells of Iranian seropositive and HCV RNA negative in plasma of patients with beta‐thalassemia major: Occult HCV infection
Authors: Kahyesh‐Esfandiary Roya , Sadigh Zohreh‐Azita , Esghaei Maryam , Bastani Mohammad‐Navid , Donyavi Tahereh , Najafi Alireza , Fakhim Atousa , Bokharaei‐Salim Farah
Published: August 2018

Beta (β) thalassemia major is a genetic blood disorder with a deficiency in the hemoglobin beta chain, requiring blood transfusion therapy. Multiple blood transfusions increase the risk of transmitting blood‐borne infections. The aim of this study is to determine the frequency of hepatitis C virus (HCV) infection in Iranian individuals with β‐thalassemia major. A total of 164 patients with β‐thalassemia major were recruited for this study. HCV RNA testing was done on plasma and peripheral blood mononuclear cells (PBMCs) from the HCV seropositive samples (with reverse transcriptase–nested polymerase chain reaction [PCR] method using primers from the 5′‐untranslated region [UTR]), and all HCV RNA positive samples were genotyped by the restriction fragment length polymorphism assay. For confirmation of the HCV genotyping in PBMCs of occult HCV infection [OCI]‐positive patients, the PCR products of two different regions of HCV (5′‐UTR and nonstructural protein 5B [NS5B]) were sequenced. Of 164 patients, 29.3% were positive for anti‐HCV antibodies, and HCV RNA was detected in the plasma specimens of 13.4% patients and in the PBMC samples of 15.2% participants. The genomic HCV‐RNA was detected in PBMC samples in 3 (6.3%) of the total 48 individuals who were HCV seropositive, and plasma HCV‐RNA negative (occult HCV infection). The subtypes of HCV in the plasma and PBMC samples of three participants were not identical. This study shows that among this group of Iranian patients with β‐thalassemia major, 13.4% had active HCV infection and 6.3% had occult HCV infection as evidenced by HCV RNA detected in PBMC specimens. Therefore, the design of a prospective study that focuses on the diagnosis of OCI can be very valuable and provide more information.
Hemorrhage of MRI and Immunohistochemical Panels Distinguish Secretory Carcinoma From Acinic Cell Carcinoma
Authors: Kuwabara Hiroko , Yamamoto Kiyohito , Terada Tetsuya , Kawata Ryo , Nagao Toshitaka , Hirose Yoshinobu
Published: August 2018

Objectives

Secretory carcinoma (SC, mammary analogue secretory carcinoma) is a salivary gland tumor with ETV6‐NTRK3 gene fusion, and its differential diagnosis includes acinic cell carcinoma (ACC). As hemorrhage is often seen in SC, we hypothesized that magnetic resonance imaging (MRI) and immunohistochemical analyses could distinguish SC from ACC.

Study Design

Retrospective study.

Methods

We used ETV6‐NTRK3 gene fusion analyses to reclassify 19 parotid gland tumors that had previously been diagnosed as SC or ACC, and then investigated hemorrhage in both hematoxylin‐eosin (H&E)‐stained sections and MRIs, and immunohistochemical expression of S‐100, mammaglobin, DOG1, and α‐amylase.

Results

The 19 tumors were genetically reclassified into 11 (58%) SC and 8 (42%) ACC. Combined S‐100 and mammaglobin were specific for SC; whereas DOG1 was specific for ACC, and α‐amylase was expressed only in 4 ACC cases (50%). H&E staining showed hemorrhage with hemosiderin deposition in all SC cases, and T2‐weighted MRI showed hypointense areas in all investigated SC cases, but not in ACC.

Conclusion

Hemorrhage with hemosiderin deposition is frequently present in SC, and hemorrhage findings in MRI and an immunohistochemical panels for S‐100, mammaglobin and DOG1 can distinguish SC from ACC.

Level of Evidence

3b
Staged Thyroidectomy: A Single Institution Perspective
Authors: Wu Che‐Wei , Sun Hui , Zhang Guang , Kim Hoon Yub , Catalfamo Antonina , Portinari Mattia , Carcoforo Paolo , Randolph Gregory W. , Chai Young Jun , Dionigi Gianlorenzo
Published: August 2018

Background

The increasing use of intraoperative neuromonitoring (IONM) in thyroid surgery has revealed the need to develop new strategies for cases in which a loss of signal (LOS) occurs on the first side of a planned total thyroidectomy.

Objectives

This study reviews the experience of the authors in using IONM for planned total thyroidectomy after LOS on the first thyroid lobe. The aims were to estimate the incidence of LOS on the first side of resection and to compare intraoperative strategies applied after this event.

Materials and Methods

Intermittent IONM was performed with stimulation of both the vagal nerve and the recurrent laryngeal nerve (RLN) (V1, R1, R2, V2). Patients underwent pre‐ and postoperative laryngoscopy. Before surgery, patients were informed that staged thyroidectomy might be required.

Results

This study analyzed 803 consecutive thyroid procedures. Of these, V2 LOS (<100 mcV) occurred after first lobe exeresis in 23 (2.8%) procedures. The surgical procedure was stopped in 20 cases (ie, staged thyroidectomy was performed). In three cases with malignancy and severe comorbidity (ASA score 3‐4), total bilateral thyroidectomy was performed as planned. No cases of bilateral RLN palsy occurred. Postoperative laryngoscopy confirmed RLN palsy in 21 of the 23 cases. All true positive patients received speech therapy. Patients who had false positive LOS (n = 2) or malignancy (n = 8) and patients who were symptomatic (n = 7) received completion thyroidectomy within 6 months. One patient received radioactive iodine therapy for hyperthyroidism. Two patients received follow up.

Conclusions

Neuromonitoring changes the surgical decision‐making process in a multidisciplinary manner. A shared decision‐making process involving the patient, anesthesiologist, and endocrinologist is suggested. In the case of intraoperative LOS on the first‐operated side in a planned total thyroidectomy, the thyroid surgeon essentially has three options for surgery on the contralateral side: 1) Perform staged thyroidectomy. This option is recommended in bilateral goiter, Graves' disease, or low‐risk thyroid carcinoma (differentiated or medullary thyroid carcinoma). The aim is to avoid bilateral vocal cord palsy. Two‐stage completion surgery is delayed until recovery of ipsilateral nerve function. 2) Perform subtotal resection on the contralateral side ventrally to the RLN plane at a safe distance from the nerve. The aim is to avoid further disease recurrence and revision surgery. 3) Perform total thyroidectomy as planned for advanced thyroid carcinoma (including undifferentiated thyroid carcinoma). The aim is to improve disease control through radioactive iodine therapy, radiation therapy, or target therapy immediately after surgery.

Level of Evidence

4
In vivo nerve identification in head and neck surgery using diffuse reflectance spectroscopy
Authors: Langhout Gerrit C. , Kuhlmann Koert F.D. , Schreuder Pim , Bydlon Torre , Smeele Ludi E. , van den Brekel Michiel W.M. , Sterenborg Henricus J.C.M. , Hendriks Benno H.W. , Ruers Theo J.M.
Published: August 2018

Background

Careful identification of nerves during head and neck surgery is essential to prevent nerve damage. Currently, nerves are identified based on anatomy and appearance, optionally combined with electromyography (EMG). In challenging cases, nerve damage is reported in up to 50%. Recently, optical techniques, like diffuse reflectance spectroscopy (DRS) and fluorescence spectroscopy (FS) show potential to improve nerve identification.

Methods

212 intra‐operative DRS/FS measurements were performed. Small nerve branches (1–3 mm), on near‐nerve adipose tissue, muscle and subcutaneous fat were measured during 11 surgical procedures. Tissue identification was based on quantified concentrations of optical absorbers and scattering parameters.

Results

Clinically comprehensive parameters showed significant differences (<0.05) between the tissues. Classification using k‐Nearest Neighbor resulted in 100% sensitivity and a specificity of 83% (accuracy 91%), for the identification of nerve against surrounding tissues.

Conclusions

DRS/FS is a potentially useful intraoperative tool for identification of nerves from adjacent tissues.

Level of Evidence

Observational proof of principle study.
Polarization Control in Graphene‐Based Polymer Waveguide Polarizer
Authors: Kim Jin Tae , Choi Hongkyw
Published: August 2018

Polarizers have been intensively investigated theoretically and experimentally, with innovative device designs and emerging optical materials. However, the polarization state and extinction ratio in a waveguide polarizer are not changeable, owing to the passive device operation principles. In this study, a polarization‐switchable graphene waveguide polarizer based on the polarization‐dependent light absorption of graphene film of different thicknesses and micro‐opto‐mechanical systems (MOMS) technology is demonstrated. A superstrate on which graphene layers of different thicknesses are integrated is positioned on the optical waveguide core, and is mechanically pushed to suppress the unwanted polarization state. Graphene thickness on the superstrate plays a key role in switching the device's polarization state: A few‐layer graphene film on the superstrate attenuates the transverse‐electric (TE) mode, making the device transverse‐magnetic (TM) passing, while a many‐layer graphene diminishes the TM mode, making the device TE passing. The dynamic optical attenuation function is automatically configured via accurate and discrete mechanical adjustment of the air gap between the superstrate and the waveguide core. The theoretical simulation and the experimental result exhibit good agreement. This work introduces an idea for tuning the polarization state in a polarization diverse coherent optical system and may contribute to a wide range of applications in MOMS systems.
Sequential facial skin rejuvenation with intense pulsed light and non‐ablative fractionated laser resurfacing in fitzpatrick skin type II–IV patients: A prospective multicenter analysis
Authors: Knight J. Matthew , Kautz Gerd
Published: August 2018

Background

While skin aging is triggered by multiple factors and typically presents with multiple manifestations, conventional treatment regimens deploy a single treatment modality. Typical approaches exploit ablative techniques, which involve considerable patient discomfort and downtime and can induce adverse events. Non‐ablative fractionated laser (NAFL) resurfacing promotes neocollagenesis, with significantly fewer complications and discomfort. At the same time, intense pulsed light (IPL) therapies have a marked impact on skin tone, with an effect on collagen deposition. This study evaluated the combined effect of same‐day, sequential IPL‐NAFL treatment on photoaging of the face.

Design

In this prospective study, 30 patients presenting Fitzpatrick skin types II–IV, elastosis scores 3–6 and mild to moderate pigmentation, underwent three sessions, of full‐face IPL therapy, followed immediately by NAFL treatment, conducted at 4–6 weeks intervals. Wrinkle/elastosis and skin qualities were scored at 1, 3, and 6 months after the last treatment session. Immediate responses were evaluated up to 30 min following treatment and adverse events were monitored throughout the study period.

Results

Wrinkle/elastosis scores gradually improved over the treatment period, with 59% of patients presenting a ≥1‐point improvement in FES scores by the 1‐month follow‐up session, which persisted also at the 6 months follow‐up visit. Good to excellent pigmentation responses were recorded for ≥63% and improvements in texture, brightness, and tightness were recorded for ≥80% of patients throughout the follow‐up period. Over 90% of the treated patients exhibited improved or much improved overall appearance. Patient scorings and satisfaction level reflected physician assessments. Treatments were well tolerated and the social downtime observed was of 1.5 ± 0.25 days.

Conclusion

The same‐day combined IPL‐NAFL regimen proved safe and elicited a significant skin rejuvenating effect, in a similar manner to that shown in other same‐day combined therapies, without prolonging downtime of each individual modality. Lasers Surg. Med. 51:141–149, 2019. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.
Impact of Nonmalignant Portal Vein Thrombosis in Transplant Recipients With Nonalcoholic Steatohepatitis
Authors: Agbim Uchenna , Jiang Yu , Kedia Satish K. , Singal Ashwani K. , Ahmed Aijaz , Bhamidimarri Kalyan Ram , Bernstein David E. , Harrison Stephen A. , Younossi Zobair M. , Satapathy Sanjaya K.
Published: August 2018

Nonalcoholic fatty liver disease is an increasingly prevalent condition, and its more severe progressive state, nonalcoholic steatohepatitis (NASH), is currently the second most common indication for wait‐listed adults in the United States. The association of portal vein thrombosis (PVT) prior to or at transplant and poor graft and patient outcomes is not well established, particularly among NASH patients who inherently have an increased hypercoagulable profile. Using the United Network for Organ Sharing data set, we analyzed graft and patient outcomes of patients transplanted for the indication of NASH with and without PVT. Of 3689 NASH transplant recipients, the prevalence of PVT was 12% (450 with PVT and 3239 without PVT). NASH transplant recipients with PVT had inferior graft and patient survival compared with NASH transplant recipients without PVT, even after adjusting for recipient and donor demographic characteristics, body mass index, synthetic dysfunction, and presence of diabetes. In a multivariate Cox regression model, NASH transplant recipients with PVT had a 37% increased risk of graft failure (hazard ratio [HR], 1.37; 95% confidence interval [CI], 1.15‐1.63; P < 0.001) and 31% increased risk of overall death (HR, 1.31; 95% CI, 1.09‐1.58; P < 0.001) compared with NASH transplant recipients without PVT at transplant. This difference in graft and patient survival was most pronounced in the early posttransplant period. These results demonstrate that NASH patients with PVT have decreased graft and patient survival independent of recipient and donor factors.
Nodal solutions for resonant and superlinear (p, 2)‐equations
Authors: He Tieshan , Lei Youfa , Zhang Meng , Sun Hongying
Published: August 2018

We consider nonlinear, nonhomogeneous elliptic Dirichlet equations driven by the sum of a p‐Laplacian and a Laplacian (so‐called (p, 2)‐equation). We are concerned with both cases (singular case) and . In the first one, the reaction is linear grow near and resonant with respect to a nonprincipal nonnegative eigenvalue. In the second case, the reaction is ()‐superlinear near and has z‐dependent zeros of constant sign. Using variational methods together with flow invariance arguments, we establish the existence of nodal solutions.
TBD‐Catalyzed Ring‐Opening Polymerization of Alkyl‐Substituted Morpholine‐2,5‐Dione Derivatives
Authors: Dirauf Michael , Bandelli Damiano , Weber Christine , Görls Helmar , Gottschaldt Michael , Schubert Ulrich S.
Published: August 2018

In a two‐step synthesis, five different alkyl‐substituted morpholine‐2,5‐dione monomers were synthesized from the natural amino acids glycine, alanine, valine, leucine, and isoleucine. The heterocyclic compounds crystallize in a boat‐like conformation and are polymerized via 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD)‐catalyzed ring‐opening polymerization (ROP) in tetrahydrofuran. Well‐defined polymers could be obtained from the monomers based on valine, leucine, and isoleucine at a feed ratio of M/I/TBD = 100/1/0.5. Kinetic studies of the ROP reveal that the molar masses and dispersities (Đ < 1.2) could be well controlled, as confirmed by size exclusion chromatography and 1H NMR spectroscopy. At conversions above 50%, the polymerization rate decreases and the dispersity slightly increases, presumably due to transesterification. Matrix‐assisted laser desorption time‐of‐flight mass spectrometry indicates the presence of polymer chains with α‐end groups derived from the initiator.
A new highly accurate domain decomposition optimal homotopy analysis method and its convergence for singular boundary value problems
Authors: Roul Pradip , Madduri Harshita
Published: August 2018

We describe a new iterative technique based on domain decomposition optimal homotopy analysis method for solving singular boundary value problems arising in various physical models in applied science and technology. This method produces approximate solution in the form of a series with easily computable components. The method is analyzed for convergence. Some computational examples are presented to illustrate the applicability and efficiency of the proposed method. The advantage in the domain decomposition optimal homotopy analysis method as compared with the classical optimal homotopy analysis method is that fewer number of solution components are required to obtain similar results. Furthermore, this method shows its advantage over the spline method and the finite difference methods.
A fast multipole accelerated indirect boundary element method for broadband scattering of elastic waves in a fluid‐saturated poroelastic domain
Authors: Liu Zhongxian , Sun Shuaijie , Cheng Alexander H.D. , Wang YiRui
Published: August 2018

A fast multipole accelerated indirect boundary element method is developed to efficiently solve the scattering of broadband waves by inhomogeneity in a fluid‐saturated 3D poroelastic space. Based on the single layer potential theory, poroelastic free‐space Green's functions of point force and fluid source are distributed on the scatterer surface at fictitious densities to construct the scattered waves. By using the plane wave expansion of 3D potential functions of compressional and shear waves, the multipole expansion and the local expansion coefficients are derived. Numerical results demonstrated that this proposed method can greatly improve the efficiency of traditional indirect boundary element method and reduce the memory requirement for 3D broadband wave scattering problems in an unbounded poroelastic medium. Problems of wave scattering by a spherical cavity, a group of cavities, and a canyon in a semiinfinite poroelastic space are investigated. Several notable scattering characteristics are revealed.
Tribological performance of ultra high molecular weight polyethylene nanocomposites reinforced with graphene nanoplatelets
Authors: Aliyu Ismaila Kayode , Mohammed Abdul Samad , Al‐Qutub Amro
Published: August 2018

Self‐lubricating polymers, such as ultrahigh molecular weight polyethylene (UHMWPE) are attractive for minimizing friction and wear in dry sliding state. However, UHMWPE has low load bearing capacity. Therefore, this research focuses on the development of graphene nanoplatelets (GNPs) reinforced UHMWPE nanocomposite for improved tribological properties to meet the current mechanical bearing applications demands. In order to realize this target, UHMWPE reinforced with different loadings (0.1, 0.25, and 0.5 wt%) of GNPs, were fabricated by ultra‐sonication and hot pressing to investigate optimum GNPs concentration. Pin on disc wear test was carried out to select the optimum composition which gives the lowest wear rate. The nanocomposites were characterized by phase, microscopic, and profilometric analyses. The results showed that UHMWPE/0.25 wt% GNPs demonstrated the highest wear resistance with a 31% reduction in wear rate as compared to the pure UHMWPE. The pressure and velocity (PV) limit for the UHMWPE/0.25 wt% GNPs nanocomposite was calculated to be 6 MPa m/s. POLYM. COMPOS., 40:E1301–E1311, 2019. © 2018 Society of Plastics Engineers
Antimicrobial peptide modification of biomaterials using supramolecular additives
Authors: Zaccaria Sabrina , van Gaal Ronald C. , Riool Martijn , Zaat Sebastian A. J. , Dankers Patricia Y. W.
Published: August 2018

Biomaterials based on non‐active polymers functionalized with antimicrobial agents by covalent modification or mixing are currently regarded as high potential solutions to prevent biomaterial associated infections that are major causes of biomedical device failure. Herewith a strategy is proposed in which antimicrobial materials are prepared by simply mixing‐and‐matching of ureido‐pyrimidinone (UPy) based supramolecular polymers with antimicrobial peptides (AMPs) modified with the same UPy‐moiety. The N‐terminus of the AMPs was coupled in solution to an UPy‐carboxylic acid synthon resulting in formation of a new amidic bond. The UPy‐functionalization of the AMPs did not affect their secondary structure, as proved by circular dichroism spectroscopy. The antimicrobial activity of the UPy‐AMPs in solution was also retained. In addition, the incorporation of UPy‐AMPs into an UPy‐polymer was stable and the final material was biocompatible. The addition of 4 mol % of UPy‐AMPs in the UPy‐polymer material protected against colonization by Escherichia coli, and methicillin‐sensitive and ‐resistant strains of Staphylococcus aureus. This modular approach enables a stable but dynamic incorporation of the antimicrobial agents, allowing at the same time for the possibility to change the nature of the polymer, as well as the use of AMPs with different activity spectra. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1926–1934
Accessible microwave synthetized conjugated poly(azomethine‐pyridine) network and its metal complexes for CO2conversion
Authors: Brivary Mari Anne , Gómez Mónica , Iglesias Marta , Maya Eva M.
Published: August 2018

A conjugated crosslinked polyazomethine containing pyridine units (PAM‐Py) was prepared from two commercial monomers, 2,6‐diaminopyridine and isophthaldehyde, under microwave heating in only 30 min. Taking advantage of its thermal and chemical stability, porosity (SBETof 192 m2/g), insolubility, and ability to coordinate metals through the pyridine or imine N atoms, ruthenium‐, aluminum‐, iron‐, and cobalt‐poly(azomethine‐pyridine) complexes (PAM‐PyM) were prepared. The resulting metal polymers were evaluated as heterogeneous catalysts for the cycloaddition of CO2to epoxides yielding selectively the corresponding cyclic carbonates. All heterogeneous catalysts showed an extraordinary effectiveness with very high yields of epoxide conversion (up to 98%), turnover numbers up to 7425, and were reused at least five times without loss in catalytic activity. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2018,56, 1946–1952
Tunable memory performances of the porphyrin terminated hyperbranched polyimides
Authors: Tan Haiwei , Yu Huaxuan , Yao Hongyan , Song Ying , Zhu Shiyang , Tian Ye , Liu Huiling , Guan Shaowei
Published: August 2018

Herein, a functional hyperbranched polyimide, denoted as ATPP‐HBPI, was synthesized by termination of polyamic acid with 5‐(4‐aminophenyl)‐10, 15, 20‐triphenylporphyrin (ATPP) and chemical imidization. Subsequently, ATPP‐HBPI was coordinated with Zn ion to give Zn‐ATPP‐HBPI. In the HBPIs, the porphyrin terminals acted as the electron donor (D) and the 6FDA moieties acted as the electron acceptor (A) to promote the electron transition. Both ATPP‐HBPI and Zn‐ATPP‐HBPI exhibited good organo‐solubility and high thermal stability. They were used as the electroactive layer to fabricate the memory device with a configuration of indium tin oxide (ITO)/HBPI/Al to evaluate their bistability. The devices exhibited different memory behaviors, WORM for ATPP‐HBPI and SRAM for Zn‐ATPP‐HBPI, respectively. Optical and electrochemical experiments and molecular simulation were carried out to illustrate this phenomenon of performance transformation. The results show that the metallization of terminal of the HBPIs provides a strategy for tailoring the memory characteristics of the devices. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1953–1961
Decreased streamflow impacts fish movement and energetics through reductions to invertebrate drift body size and abundance
Authors: Caldwell Timothy J. , Rossi Gabriel J. , Henery Rene E. , Chandra Sudeep
Published: August 2018

Streamflow drives ecological processes across multiple trophic levels making it a “master variable in lotic systems.” In mountain systems, especially those that are regulated, increased frequency of droughts and reductions in snowpack may alter future streamflow regimes and impact ecological processes. We monitored invertebrate drift abundance, size, and diversity as a function of streamflow. We then related these variables to fish movement and energetic efficiencies in the Upper Shasta River in California, above and below a large streamflow diversion. Invertebrate drift biomass was significantly less at impaired flows compared with unimpaired flows, and average body size of invertebrates decreased with decreasing streamflow. Generally, fish movement was greater at the impaired flow site (>50% of the time fish were tracked). Fish movement at the upstream site was negatively related to the size of individual prey items and amount of prey available, and significant drivers were not detected in the flow‐impaired site. Energetic efficiency was reduced by over 70% when search foraging took place, and the net rate of energetic intake was below 0 J/s for low‐flow periods. Our results suggest that fish foraging behaviour may be influenced indirectly by altered streamflow through changes to amount and size of invertebrate drift. A shift to foraging behaviour, coupled with low food availability, results in decreased energetic efficiency. Future prescriptions of flow rates to regulated rivers should account for changes to invertebrate drift, fish behaviour, and fish energetics on seasonal time scales.
A Microfluidic Strategy for Controllable Generation of Water‐in‐Water Droplets as Biocompatible Microcarriers
Authors: Liu Hai‐Tao , Wang Hui , Wei Wen‐Bo , Liu Hui , Jiang Lei , Qin Jian‐Hua
Published: August 2018

Droplet microfluidics has been widely applied in functional microparticles fabricating, tissue engineering, and drug screening due to its high throughput and great controllability. However, most of the current droplet microfluidics are dependent on water‐in‐oil (W/O) systems, which involve organic reagents, thus limiting their broader biological applications. In this work, a new microfluidic strategy is described for controllable and high‐throughput generation of monodispersed water‐in‐water (W/W) droplets. Solutions of polyethylene glycol and dextran are used as continuous and dispersed phases, respectively, without any organic reagents or surfactants. The size of W/W droplets can be precisely adjusted by changing the flow rate of dispersed and continuous phases and the valve switch cycle. In addition, uniform cell‐laden microgels are fabricated by introducing the alginate component and rat pancreatic islet (β‐TC6) cell suspension to the dispersed phase. The encapsulated islet cells retain high viability and the function of insulin secretion after cultivation for 7 days. The high‐throughput droplet microfluidic system with high biocompatibility is stable, controllable, and flexible, which can boost various chemical and biological applications, such as bio‐oriented microparticles synthesizing, microcarriers fabricating, tissue engineering, etc.
On the trade, growth, and welfare effects of intellectual property rights protection
Authors: Saito Yuki
Published: August 2018

To examine how intellectual property rights protection affects trade, growth, and welfare, I develop a two‐country R&D‐based growth model in which final goods firms in both countries determine the range of imported varieties in the overall use of intermediate inputs. I show that strengthening patent protection in either country increases the range of imported varieties of intermediate goods and stimulates economic growth in the country that strengthened patent protection. Moreover, I also show that the Nash equilibrium level of patent protection is stronger than the globally optimal level of patent protection.
Why factors facilitating collusion may not predict cartel occurrence — experimental evidence
Authors: Fonseca Miguel A. , Li Yan , Normann Hans‐Theo
Published: August 2018

Factors facilitating collusion may not successfully predict cartel occurrence: When a factor predicts that collusion (explicit and tacit) becomes easier, firms might be less inclined to set up a cartel simply because tacit coordination already tends to go in hand with supra‐competitive profits. We illustrate this issue with laboratory data. We run n‐firm Cournot experiments with written cheap‐talk communication between players and we compare them to treatments without the possibility to talk. We conduct this comparison for two, four, and six firms. We find that two firms indeed find it easier to collude tacitly but that the number of firms does not significantly affect outcomes with communication. As a result, the payoff gain from communication increases with the number of firms, at a decreasing rate.
Requiring Versus Recommending Preparation Before Class: Does It Matter?
Authors: Andersen Martin S. , Gicheva Dora , Sarbaum Jeffrey
Published: August 2018

Asking students to come to class prepared is quite common in undergraduate and graduate education. We use a quasiexperimental design to assess whether requiring undergraduate students in an introductory course to review prior to lecture the material that will be taught in class enhances their understanding of key concepts. We find that requiring rather than recommending preparation before class increases exam scores by about a quarter of a standard deviation, or roughly a third of a letter grade, for students in the second and third quartiles of the ability distribution but has little impact on very high‐ or low‐ability students. We also estimate local average treatment effects, from which we draw a similar conclusion: reviewing the material before lecture benefits students in the middle of the ability distribution but has essentially no impact on the top and bottom quartiles.
Evolutionary Management: From Theory to Action
Authors: Donaires Omar Sacilotto , Martinelli Dante Pinheiro
Published: August 2018

The concept of evolutionary management suggests that the understanding of the autonomous operating principles of the dynamics of the system can be of interest for the development of organizations and their ability to adapt to unpredictable changes. This paper presents the concept of evolutionary management and discusses how it can be moved from theory to practice by using two systems methodologies: soft systems methodology (SSM) and the viable system model (VSM). The authors provide a conceptual framework and, by means of an application in a real company, exemplify how SSM and the VSM can be used together to enable the practice of evolutionary management and achieve its benefits in practice. As a theoretical outcome of the research work, some principles are formulated for the practice of evolutionary management and illustrated with examples drawn from the application. © 2018 John Wiley & Sons, Ltd.
Hydride Amide and Hydride Phenolate Complexes of NHC Coordinated Aluminum
Authors: Hock Andreas , Schneider Heidi , Krahfuß Mirjam J. , Radius Udo
Published: August 2018

The reaction of NHC alane adducts NHC·AlH3 (NHC = N‐Heterocyclic Carbene; NHC = iPr2Im, Dipp2Im; R2Im = 1,3‐di‐organyl‐imidazolin‐2‐ylidene; iPr = isopropyl; Dipp = 2,6‐diisopropylphenyl) with secondary amines HNR2 [R = iPr, Ph, Si(CH3)3] and the reaction of the trimethylamine alane adduct (NMe3)·AlH3 with secondary amines followed by the reaction with the NHC both lead to formation of the compounds NHC·AlH2(NR2) 1–6 [NHC = iPr2Im, Dipp2Im, R = iPr, Ph, Si(CH3)3]. These compounds are stable in solution up to temperatures of 90 °C. In contrast to the NHC alane adduct (iPr2Im)·AlH3 (I) and (Dipp2Im)·AlH3 (II), no ring expansion reaction to six‐membered heterocyclic rings or ring opening reaction were observed for the reaction of (iPr2Im)·AlH2(NR2) with another equivalent of the NHCs iPr2Im or Dipp2Im. Thus, amide substituted NHC alane adducts show a much high stability compared to the parent compounds NHC·AlH3. Furthermore, the reaction of NHC·AlH3 (NHC = iPr2Im, Dipp2Im) with 2,4,6‐trimethylphenol leads to the formation of the adducts NHC·AlH3–n(OMes)n 7–10 (n = 1, 2). The reaction with n ≥ 3 equivalent of 2,4,6‐trimethylphenol afforded the imidazolium salt [Dipp2ImH]+[Al(OMes)4]– (11). The compounds 7–11 are also stable with respect to ring expansion after addition of another equivalent NHC.
Heating up exotic RG flows with holography
Authors: Bea Yago , Mateos David
Published: August 2018

Abstract

We use holography to study finite-temperature deformations of RG flows that have exotic properties from an RG viewpoint. The holographic model consists of five-dimensional gravity coupled to a scalar field with a potential. Each negative extrema of the potential defines a dual conformal field theory. We find all the black brane solutions on the gravity side and use them to construct the thermal phase diagrams of the dual theories. We find an intricate phase structure that reflects and extends the exotic properties at zero temperature.
Psychometric Models of Small Group Collaborations
Authors: Halpin Peter F. , Bergner Yoav
Published: August 2018

The social combination theory of group problem solving is used to extend existing psychometric models to collaborative settings. A model for pairwise group work is proposed, the implications of the model for assessment design are considered, and its estimation is addressed. The results are illustrated with an empirical example in which dyads work together on a twelfth-grade level mathematics assessment. In conclusion, attention is given to avenues of research that seem most fruitful for advancing current initiatives concerning the assessment of collaboration, teamwork, and related constructs.
Introduction to Special Section: Why Marketing Still Matters in Oceania and Asia
Authors: Phau Ian , Garrett Tony
Published: August 2018

Cultural diversity is the norm in today's society, and past research has shown that ethnic cues in advertisements are effective in targeting ethnic consumers. This study extends this research stream by examining how ethnic identify impacts ethnic consumers’ perceptions of advertising in ethnic versus mainstream newspapers. The results show that ethnic consumers with higher ethnic identity have more positive responses towards advertisements with ethnic cues, particularly when the advertisements appear in ethnic newspapers. By contrast, for the same advertisements, mainstream media appears less effective in eliciting positive responses. Ethnic consumers with higher ethnic identity are also more likely to purchase and recommend products advertised in ethnic media. These findings offer insights to marketers and businesses who are targeting ethnic consumers. They shed light on when and how to use ethnic cues, particularly in ethnic media, in order to achieve desirable marketing and communication strategies that target ethnic consumers.
FromThe Composition of Foodsusing chemical analysis…to micronutrients and beyond
Authors: Walker Ann F.
Published: August 2018

In the early 1930s, after obtaining her PhD on the carbohydrates in apples, Dr Elsie Widdowson embarked on a postgraduate course in dietetics at King’s College of Household and Social Science, London. During the hospital training element of this course at St Bartholomew’s Hospital, she was appalled at the inaccuracy of the food compositional data being used to formulate medically-prescribed diets. She resolved to change matters, and after she had joined Dr McCance’s team she realized that they had already obtained sufficient new analytical data on the majority of the food groups to form the basis of completely new tables.
From early nutrition and later development...to underlying mechanisms and optimal health
Authors: Dauncey M. J.
Published: August 2018

‘Life is a country that the old have seen, and lived in. Those who have to travel through it can only learn the way from them.’

Joseph Joubert, 1842

This quotation is perhaps especially appropriate when considering the extensive contributions made by Professor McCance and Dr Widdowson to the field of early nutrition and later development. A detailed knowledge of their work in this area is of undoubted value both in interpreting many recent findings and in the design of new investigations. The first part of this paper presents a brief overview of some of their most significant studies. Their implications at both the fundamental and applied levels are then discussed, especially in relation to the role of nutrition in health and disease. Finally, potential mechanisms by which development may be modified by early nutrition are considered.
From animals in the service of nutrition...to the potential of biotechnology
Authors: Hall Judith
Published: August 2018

In 1986, in her paper, ‘Animals in the service of human nutrition’, celebrating the award of the E. V. McCollum International Lectureship in Nutrition, Dr Elsie Widdowson observed: ‘Animals have served human nutrition well over the past century.... They are still of great service in human nutrition and may be more essential in the future as proper animal models for human diseases are discovered’. Ten years on, those animal models are an integral part of nutrition research and are providing fundamental tools to study the effects of diet on many of the major diseases of the Western world, including cardiovascular disease, obesity and cancer. Many of these models have been developed through the use of recombinant DNA technology and the expression of normal or mutated genes in the genome of transgenic mice.
John Rawls métaéthicien?
Authors: DESMONS OPHÉLIE
Published: August 2018

Les critiques aussi bien que les défenseurs contemporains du constructivisme métaéthique jugent incomplet le constructivisme développé par John Rawls. Ils considèrent que son agnosticisme ontologique est un signe évident de l’incomplétude de sa position métaéthique. L’ambition de cet article est de contester ce verdict généralement accepté, en produisant une interprétation alternative de l’agnosticisme ontologique de Rawls, selon laquelle cet agnosticisme est l’effet de sa position métaéthique plutôt qu’un défaut de position métaéthique. Sur cette base, je pose à nouveaux frais la question de l’originalité et de l’attractivité de la métaéthique rawlsienne. Je montre que l’attractivité de la métaéthique rawlsienne se situe dans sa capacité à saisir l’historicité spécifique des normes de justice.