bluuebunny/crossref_metadata_2025 huggingface dataset:
Roles of Cyclic AMP Response Element Binding Activation in the ERK1/2 and p38 MAPK Signalling Pathway in Central Nervous System, Cardiovascular System, Osteoclast Differentiation and Mucin and Cytokine Production
Authors: Koga Yasuhiko , Tsurumaki Hiroaki , Aoki-Saito Haruka , Sato Makiko , Yatomi Masakiyo , Takehara Kazutaka , Hisada Takeshi
Published: March 2019

There are many downstream targets of mitogen-activated protein kinase (MAPK) signalling that are involved in neuronal development, cellular differentiation, cell migration, cancer, cardiovascular dysfunction and inflammation via their functions in promoting apoptosis and cell motility and regulating various cytokines. It has been reported that cyclic AMP response element-binding protein (CREB) is phosphorylated and activated by cyclic AMP signalling and calcium/calmodulin kinase. Recent evidence also points to CREB phosphorylation by the MAPK signalling pathway. However, the specific roles of CREB phosphorylation in MAPK signalling have not yet been reviewed in detail. Here, we describe the recent advances in the study of this MAPK-CREB signalling axis in human diseases. Overall, the crosstalk between extracellular signal-related kinase (ERK) 1/2 and p38 MAPK signalling has been shown to regulate various physiological functions, including central nervous system, cardiac fibrosis, alcoholic cardiac fibrosis, osteoclast differentiation, mucin production in the airway, vascular smooth muscle cell migration, steroidogenesis and asthmatic inflammation. In this review, we focus on ERK1/2 and/or p38 MAPK-dependent CREB activation associated with various diseases to provide insights for basic and clinical researchers.
Navigating the Landscape of Tumor Extracellular Vesicle Heterogeneity
Authors: Roy Sabrina , Lin Hsing-Ying , Chou Chung-Yu , Huang Chen-Han , Small Julia , Sadik Noah , Ayinon Caroline M. , Lansbury Elizabeth , Cruz Lilian , Yekula Anudeep , Jones Pamela S. , Balaj Leonora , Carter Bob S.
Published: March 2019

The last decade has seen a rapid expansion of interest in extracellular vesicles (EVs) released by cells and proposed to mediate intercellular communication in physiological and pathological conditions. Considering that the genetic content of EVs reflects that of their respective parent cell, many researchers have proposed EVs as a source of biomarkers in various diseases. So far, the question of heterogeneity in given EV samples is rarely addressed at the experimental level. Because of their relatively small size, EVs are difficult to reliably isolate and detect within a given sample. Consequently, standardized protocols that have been optimized for accurate characterization of EVs are lacking despite recent advancements in the field. Continuous improvements in pre-analytical parameters permit more efficient assessment of EVs, however, methods to more objectively distinguish EVs from background, and to interpret multiple single-EV parameters are lacking. Here, we review EV heterogeneity according to their origin, mode of release, membrane composition, organelle and biochemical content, and other factors. In doing so, we also provide an overview of currently available and potentially applicable methods for single EV analysis. Finally, we examine the latest findings from experiments that have analyzed the issue at the single EV level and discuss potential implications.
Matrix Metalloproteinases in Pulmonary and Central Nervous System Tuberculosis—A Review
Authors: Rohlwink Ursula K. , Walker Naomi F. , Ordonez Alvaro A. , Li Yifan J. , Tucker Elizabeth W. , Elkington Paul T. , Wilkinson Robert J. , Wilkinson Katalin A.
Published: March 2019

Tuberculosis (TB) remains the single biggest infectious cause of death globally, claiming almost two million lives and causing disease in over 10 million individuals annually. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes with various physiological roles implicated as key factors contributing to the spread of TB. They are involved in the breakdown of lung extracellular matrix and the consequent release of Mycobacterium tuberculosis bacilli into the airways. Evidence demonstrates that MMPs also play a role in central nervous system (CNS) tuberculosis, as they contribute to the breakdown of the blood brain barrier and are associated with poor outcome in adults with tuberculous meningitis (TBM). However, in pediatric TBM, data indicate that MMPs may play a role in both pathology and recovery of the developing brain. MMPs also have a significant role in HIV-TB-associated immune reconstitution inflammatory syndrome in the lungs and the brain, and their modulation offers potential novel therapeutic avenues. This is a review of recent research on MMPs in pulmonary and CNS TB in adults and children and in the context of co-infection with HIV. We summarize different methods of MMP investigation and discuss the translational implications of MMP inhibition to reduce immunopathology.
Effects of Magnesium Deficiency on Mechanisms of Insulin Resistance in Type 2 Diabetes: Focusing on the Processes of Insulin Secretion and Signaling
Authors: Kostov Krasimir
Published: March 2019

Magnesium (Mg2+) is an essential mineral for human health and plays an important role in the regulation of glucose homeostasis and insulin actions. Despite the widespread clinical evidences for the association of Mg2+ deficiency (MgD) and type 2 diabetes mellitus (T2D), molecular mechanisms by which Mg2+ contributes to insulin resistance (IR) are still under discussion. Mg2+ regulates electrical activity and insulin secretion in pancreatic beta-cells. Intracellular Mg2+ concentrations are critical for the phosphorylation of the insulin receptor and other downstream signal kinases of the target cells. Low Mg2+ levels result in a defective tyrosine kinase activity, post-receptor impairment in insulin action, altered cellular glucose transport, and decreased cellular glucose utilization, which promotes peripheral IR in T2D. MgD triggers chronic systemic inflammation that also potentiates IR. People with T2D may end up in a vicious circle in which MgD increases IR and IR causes MgD, that requires periodic monitoring of serum Mg2+ levels.
Decreased Protein Kinase C-β Type II Associated with the Prominent Endotoxin Exhaustion in the Macrophage of FcGRIIb−/− Lupus Prone Mice is Revealed by Phosphoproteomic Analysis
Authors: Ondee Thunnicha , Jaroonwitchawan Thiranut , Pisitkun Trairak , Gillen Joseph , Nita-Lazar Aleksandra , Leelahavanichkul Asada , Somparn Poorichaya
Published: March 2019

Dysfunction of FcGRIIb, the only inhibitory receptor of the FcGR family, is commonly found in the Asian population and is possibly responsible for the extreme endotoxin exhaustion in lupus. Here, the mechanisms of prominent endotoxin (LPS) tolerance in FcGRIIb−/− mice were explored on bone marrow-derived macrophages using phosphoproteomic analysis. As such, LPS tolerance decreased several phosphoproteins in the FcGRIIb−/− macrophage, including protein kinase C-β type II (PRKCB), which was associated with phagocytosis function. Overexpression of PRKCB attenuated LPS tolerance in RAW264.7 cells, supporting the role of this gene in LPS tolerance. In parallel, LPS tolerance in macrophages and in mice was attenuated by phorbol 12-myristate 13-acetate (PMA) administration. This treatment induced several protein kinase C families, including PRKCB. However, PMA attenuated the severity of mice with cecal ligation and puncture on LPS tolerance preconditioning in FcGRIIb−/− but not in wild-type cells. The significant reduction of PRKCB in the FcGRIIb−/− macrophage over wild-type cell possibly induced the more severe LPS-exhaustion and increased the infection susceptibility in FcGRIIb−/− mice. PMA induced PRKCB, improved LPS-tolerance, and attenuated sepsis severity, predominantly in FcGRIIb−/− mice. PRKCB enhancement might be a promising strategy to improve macrophage functions in lupus patients with LPS-tolerance from chronic infection.
Changes in Human Foetal Osteoblasts Exposed to the Random Positioning Machine and Bone Construct Tissue Engineering
Authors: Mann Vivek , Grimm Daniela , Corydon Thomas J , Krüger Marcus , Wehland Markus , Riwaldt Stefan , Sahana Jayashree , Kopp Sascha , Bauer Johann , Reseland Janne E. , Infanger Manfred , Mari Lian Aina , Okoro Elvis , Sundaresan Alamelu
Published: March 2019

Human cells, when exposed to both real and simulated microgravity (s-µg), form 3D tissue constructs mirroring in vivo architectures (e.g., cartilage, intima constructs, cancer spheroids and others). In this study, we exposed human foetal osteoblast (hFOB 1.19) cells to a Random Positioning Machine (RPM) for 7 days and 14 days, with the purpose of investigating the effects of s-µg on biological processes and to engineer 3D bone constructs. RPM exposure of the hFOB 1.19 cells induces alterations in the cytoskeleton, cell adhesion, extra cellular matrix (ECM) and the 3D multicellular spheroid (MCS) formation. In addition, after 7 days, it influences the morphological appearance of these cells, as it forces adherent cells to detach from the surface and assemble into 3D structures. The RPM-exposed hFOB 1.19 cells exhibited a differential gene expression of the following genes: transforming growth factor beta 1 (TGFB1, bone morphogenic protein 2 (BMP2), SRY-Box 9 (SOX9), actin beta (ACTB), beta tubulin (TUBB), vimentin (VIM), laminin subunit alpha 1 (LAMA1), collagen type 1 alpha 1 (COL1A1), phosphoprotein 1 (SPP1) and fibronectin 1 (FN1). RPM exposure also induced a significantly altered release of the cytokines and bone biomarkers sclerostin (SOST), osteocalcin (OC), osteoprotegerin (OPG), osteopontin (OPN), interleukin 1 beta (IL-1β) and tumour necrosis factor 1 alpha (TNF-1α). After the two-week RPM exposure, the spheroids presented a bone-specific morphology. In conclusion, culturing cells in s-µg under gravitational unloading represents a novel technology for tissue-engineering of bone constructs and it can be used for investigating the mechanisms behind spaceflight-related bone loss as well as bone diseases such as osteonecrosis or bone injuries.
Molecular Mechanisms Driving Progression of Liver Cirrhosis towards Hepatocellular Carcinoma in Chronic Hepatitis B and C Infections: A Review
Authors: Kanda Tatsuo , Goto Taichiro , Hirotsu Yosuke , Moriyama Mitsuhiko , Omata Masao
Published: March 2019

Almost all patients with hepatocellular carcinoma (HCC), a major type of primary liver cancer, also have liver cirrhosis, the severity of which hampers effective treatment for HCC despite recent progress in the efficacy of anticancer drugs for advanced stages of HCC. Here, we review recent knowledge concerning the molecular mechanisms of liver cirrhosis and its progression to HCC from genetic and epigenomic points of view. Because ~70% of patients with HCC have hepatitis B virus (HBV) and/or hepatitis C virus (HCV) infection, we focused on HBV- and HCV-associated HCC. The literature suggests that genetic and epigenetic factors, such as microRNAs, play a role in liver cirrhosis and its progression to HCC, and that HBV- and HCV-encoded proteins appear to be involved in hepatocarcinogenesis. Further studies are needed to elucidate the mechanisms, including immune checkpoints and molecular targets of kinase inhibitors, associated with liver cirrhosis and its progression to HCC.
Purification, Characterization and Degradation Performance of a Novel Dextranase from Penicillium cyclopium CICC-4022
Authors: Huang Ruijie , Zhong Lei , Xie Fengwei , Wei Liming , Gan Lanfang , Wang Xuejiao , Liao Anping
Published: March 2019

A novel dextranase was purified from Penicillium cyclopium CICC-4022 by ammonium sulfate fractional precipitation and gel filtration chromatography. The effects of temperature, pH and some metal ions and chemicals on dextranase activity were investigated. Subsequently, the dextranase was used to produce dextran with specific molecular mass. Weight-average molecular mass (Mw) and the ratio of weight-average molecular mass/number-average molecular mass, or polydispersity index (Mw/Mn), of dextran were measured by multiple-angle laser light scattering (MALS) combined with gel permeation chromatography (GPC). The dextranase was purified to 16.09-fold concentration; the recovery rate was 29.17%; and the specific activity reached 350.29 U/mg. Mw of the dextranase was 66 kDa, which is similar to dextranase obtained from other Penicillium species reported previously. The highest activity was observed at 55 °C and a pH of 5.0. This dextranase was identified as an endodextranase, which specifically degraded the α-1,6 glucosidic bonds of dextran. According to metal ion dependency tests, Li+, Na+ and Fe2+ were observed to effectively improve the enzymatic activity. In particular, Li+ could improve the activity to 116.28%. Furthermore, the dextranase was efficient at degrading dextran and the degradation rate can be well controlled by the dextranase activity, substrate concentration and reaction time. Thus, our results demonstrate the high potential of this dextranase from Penicillium cyclopium CICC-4022 as an efficient enzyme to produce specific clinical dextrans.
Cloning, Expression, and Characterization of a Psychrophilic Glucose 6-Phosphate Dehydrogenase from Sphingomonas sp. PAMC 26621
Authors: TranNgoc Kiet , Pham Nhung , Lee ChangWoo , Jang Sei-Heon
Published: March 2019

Glucose 6-phosphate dehydrogenase (G6PD) (EC 1.1.1.363) is a crucial regulatory enzyme in the oxidative pentose phosphate pathway that provides reductive potential in the form of NADPH, as well as carbon skeletons for the synthesis of macromolecules. In this study, we report the cloning, expression, and characterization of G6PD (SpG6PD1) from a lichen-associated psychrophilic bacterium Sphingomonas sp. PAMC 26621. SpG6PD1 was expressed in Escherichia coli as a soluble protein, having optimum activity at pH 7.5–8.5 and 30 °C for NADP+ and 20 °C for NAD+. SpG6PD1 utilized both NADP+ and NAD+, with the preferential utilization of NADP+. A high Km value for glucose 6-phosphate and low activation enthalpy (ΔH‡) compared with the values of mesophilic counterparts indicate the psychrophilic nature of SpG6PD1. Despite the secondary structure of SpG6PD1 being maintained between 4–40 °C, its activity and tertiary structure were better preserved between 4–20 °C. The results of this study indicate that the SpG6PD1 that has a flexible structure is most suited to a psychrophilic bacterium that is adapted to a permanently cold habitat.
HgS Inhibits Oxidative Stress Caused by Hypoxia through Regulation of 5-HT Metabolism Pathway
Authors: He Qiangqiang , Ma Ji , Kalavagunta Praveen Kumar , Zhou Liangliang , Zhu Junyi , Dong Jing , Ahmad Owais , Du Yuzhi , Wei Lixin , Shang Jing
Published: March 2019

This study aims to reveal the potential relationship between 5-HT and oxidative stress in the organism. Our in vitro experiments in RIN-14B cells showed that anoxia leads the cells to the state of oxidative stress. Administration of exogenous 5-HT exacerbated this effect, whereas the inhibition of Tph1, LP533401 alleviated the oxidative stress. Several research articles reported that Cinnabar (consists of more than 96% mercury sulfide, HgS), which is widely used in both Chinese and Indian traditional medicine prescriptions, has been involved in the regulation of 5-HT. The present research revealed that HgS relieved the level of oxidative stress of RIN-14B cells. This pharmacological activity was also observed in the prescription drug Zuotai, in which HgS accounts for 54.5%, and these effects were found to be similar to LP533401, an experimental drug to treat pulmonary hypertension. Further, our in vivo experiments revealed that the administration of cinnabar or prescription drug Zuotai in zebrafish reduced the reactive oxygen species (ROS) induced by hypoxia and cured behavioral abnormalities. Taken together, in organisms with hypoxia induced oxidative stress 5-HT levels were found to be abnormally elevated, indicating that 5-HT could regulate oxidative stress, and the decrease in the 5-HT levels, behavioral abnormalities after treatment with cinnabar and Zuotai, we may conclude that the therapeutic and pharmacologic effect of cinnabar and Zuotai may be based on the regulation of 5-HT metabolism and relief of oxidative stress. Even though they aren’t toxic at the present dosage in both cell lines and zebrafish, their dose dependent toxicities are yet to be evaluated.
Estimating Spatiotemporal Information from Behavioral Sensing Data of Wheelchair Users by Machine Learning Technologies
Authors: Yairi Ikuko Eguchi , Takahashi Hiroki , Watanabe Takumi , Nagamine Kouya , Fukushima Yusuke , Matsuo Yutaka , Iwasawa Yusuke
Published: March 2019

Recent expansion of intelligent gadgets, such as smartphones and smart watches, familiarizes humans with sensing their activities. We have been developing a road accessibility evaluation system inspired by human sensing technologies. This paper introduces our methodology to estimate road accessibility from the three-axis acceleration data obtained by a smart phone attached on a wheelchair seat, such as environmental factors, e.g., curbs and gaps, which directly influence wheelchair bodies, and human factors, e.g., wheelchair users’ feelings of tiredness and strain. Our goal is to realize a system that provides the road accessibility visualization services to users by online/offline pattern matching using impersonal models, while gradually learning to improve service accuracy using new data provided by users. As the first step, this paper evaluates features acquired by the DCNN (deep convolutional neural network), which learns the state of the road surface from the data in supervised machine learning techniques. The evaluated results show that the features can capture the difference of the road surface condition in more detail than the label attached by us and are effective as the means for quantitatively expressing the road surface condition. This paper developed and evaluated a prototype system that estimated types of ground surfaces focusing on knowledge extraction and visualization.
Chemical Compounds from Female and Male Rectal Pheromone Glands of the Guava Fruit Fly, Bactrocera correcta
Authors: Zhang Xiuge , Wei Chengmei , Miao Jin , Zhang Xiaojiao , Wei Bo , Dong Wenxia , Xiao Chun
Published: March 2019

The guava fruit fly, Bactrocera correcta, is one of the major pests affecting mango (Mangifera indica) and guava (Psidium guajava) production in China. The compound β-caryophyllene was identified from the rectal gland extracts of wild B. correcta males and was demonstrated to be a more specific and potent male lure than methyl eugenol (ME) for B. correcta. In order to find potential additional pheromone attractants for the monitoring and mass-trapping of this fruit fly, a series of chemical and behavioral assays were conducted in this study. Ten compounds were identified from the rectal glands of virgin B. correcta females. These compounds consisted of five major compounds (i.e., ethyl dodecanoate, ethyl tetradecanoate, ethyl (E)-9-hexadecenoate, ethyl hexadecanoate, and ethyl (Z)-9-octadecenoate) in high quantities, and other compounds (i.e., octanal, N-(3-methylbutyl) acetamide, (Z)-9-tricosene, ethyl octadecanoate, and ethyl eicosanoate) in trace amounts, while virtually no compounds were found in male rectal glands. The bioassays indicate that female rectal gland extracts are attractive to virgin females and males. Furthermore, a cyclical production of the five major compounds was found, recurring at roughly 10-d intervals with peaks in 10–13-, 25-, and 35-d-old females. Collectively, these results will contribute to the understanding of pheromone communication in B. correcta and may provide important information for improving existing monitoring and control methods for this pest.
Incidence and Impact of Acute Kidney Injury after Liver Transplantation: A Meta-Analysis
Authors: Thongprayoon Charat , Kaewput Wisit , Thamcharoen Natanong , Bathini Tarun , Watthanasuntorn Kanramon , Lertjitbanjong Ploypin , Sharma Konika , Salim Sohail Abdul , Ungprasert Patompong , Wijarnpreecha Karn , Kröner Paul T. , Aeddula Narothama Reddy , Mao Michael A , Cheungpasitporn Wisit
Published: March 2019

Background: The study’s aim was to summarize the incidence and impacts of post-liver transplant (LTx) acute kidney injury (AKI) on outcomes after LTx. Methods: A literature search was performed using the MEDLINE, EMBASE and Cochrane Databases from inception until December 2018 to identify studies assessing the incidence of AKI (using a standard AKI definition) in adult patients undergoing LTx. Effect estimates from the individual studies were derived and consolidated utilizing random-effect, the generic inverse variance approach of DerSimonian and Laird. The protocol for this systematic review is registered with PROSPERO (no. CRD42018100664). Results: Thirty-eight cohort studies, with a total of 13,422 LTx patients, were enrolled. Overall, the pooled estimated incidence rates of post-LTx AKI and severe AKI requiring renal replacement therapy (RRT) were 40.7% (95% CI: 35.4%–46.2%) and 7.7% (95% CI: 5.1%–11.4%), respectively. Meta-regression showed that the year of study did not significantly affect the incidence of post-LTx AKI (p = 0.81). The pooled estimated in-hospital or 30-day mortality, and 1-year mortality rates of patients with post-LTx AKI were 16.5% (95% CI: 10.8%–24.3%) and 31.1% (95% CI: 22.4%–41.5%), respectively. Post-LTx AKI and severe AKI requiring RRT were associated with significantly higher mortality with pooled ORs of 2.96 (95% CI: 2.32–3.77) and 8.15 (95%CI: 4.52–14.69), respectively. Compared to those without post-LTx AKI, recipients with post-LTx AKI had significantly increased risk of liver graft failure and chronic kidney disease with pooled ORs of 3.76 (95% CI: 1.56–9.03) and 2.35 (95% CI: 1.53–3.61), respectively. Conclusion: The overall estimated incidence rates of post-LTx AKI and severe AKI requiring RRT are 40.8% and 7.0%, respectively. There are significant associations of post-LTx AKI with increased mortality and graft failure after transplantation. Furthermore, the incidence of post-LTx AKI has remained stable over the ten years of the study.
Cardioprotective Properties of Omecamtiv Mecarbil against Ischemia and Reperfusion Injury
Authors: Stroethoff Martin , Behmenburg Friederike , Meierkord Simon , Bunte Sebastian , Mayer Felix , Mathes Alexander , Heinen André , Hollmann Markus W. , Huhn Ragnar
Published: March 2019

Omecamtiv mecarbil (OM) is a first-in-class myosin activator. It was developed as a new inotropic therapy option for heart failure and is currently the object of a phase 3 clinical trial program. OM activates ryanodine receptors, which were shown to be involved in cardioprotection induced by conditioning strategies. We hypothesize that OM exerts a concentration-dependent cardioprotective effect through pre- and postconditioning. Isolated male Wistar rat hearts underwent 33 min of global ischemia and 60 min of reperfusion. OM was administered in various concentrations (1, 3, 10, and 30 µM) over 10 min prior to ischemia. Based on these results, in subsequent experiments 3 and 10 µM OM were given over 10 min after ischemia. Infarct sizes were determined by TTC staining. In controls, the infarct size was 60% ± 10% and 59% ± 12%, respectively. Ten micromolar OM before ischemia reduced the infarct size to 33% ± 8%. The lower concentrations did not initiate cardioprotection, and the next highest concentration did not enhance the protective effect. Even if 10 μM OM was given in the early reperfusion phase, it significantly reduced the infarct size (31% ± 6%), whereas 3 μM OM did not trigger a protective effect (58% ± 15%). This study shows for the first time that OM induces cardioprotection by pre- and postconditioning with a binary phenomenon, which is either ineffective or has a maximal effect.
Relationship between the Duration of the Second Stage of Labour and Neonatal Morbidity
Authors: Infante-Torres Nuria , Molina-Alarcón Milagros , Gómez-Salgado Juan , Rodríguez-Almagro Julián , Rubio-Álvarez Ana , Hernández-Martínez Antonio
Published: March 2019

(1) Background: To assess the relationship between the duration of the second stage of labour and the neonatal morbidity risk; (2) Methods: An observational, analytical, retrospective cohort study was performed at the “Mancha-Centro” Hospital (Spain) during the 2013–2016 period. Data were collected from 3863 women who gave a vaginal birth. The studied neonatal morbidity variables were umbilical cord arterial pH, 5-min Apgar score, need for advanced neonatal resuscitation, and a composite neonatal morbidity variable on which the multivariate analysis was done. A univariate analysis was used for the potential risk factors and a multivariate analysis with binary logistic regression to control for possible confounding factors; (3) Results: The univariate analysis showed a statistically significant relationship between the duration of the second stage of labour and a high risk of advanced neonatal resuscitation and composite neonatal morbidity in multiparous women. However, after performing the multivariate analysis for the variable “composite neonatal morbidity”, we observed no relationship with the duration of the second stage of labour in either nulliparous or multiparous women; (4) Conclusions: The duration of the second stage of labour was not related to an increased risk of neonatal morbidity in our study population.
An Analysis of the Causes of Deforestation in Malawi: A Case of Mwazisi
Authors: Ngwira Susan , Watanabe Teiji
Published: March 2019

Deforestation is recognized as a major driver of the loss of biodiversity and ecosystem services. It also disturbs natural processes such as biogeochemical, hydrological, and ecological cycles. In Malawi, deforestation is estimated to be responsible for the loss of 33,000 hectares per year, and is mainly attributed to agriculture expansion, tobacco growing, and excessive use of biomass. However, little research has been conducted at either the local level or that of forests located on customary land. This research aimed to identify and analyze the underlying driving factors associated with the proximate factors of agriculture expansion, tobacco growing, and brick burning in Mwazisi. Landsat images for 1991, 2004, and 2017 were downloaded from the United States Geological Survey website and used to analyze changes in forest cover. Interviews with households (n = 399) and Natural Resource Committee members, a focus group discussion with key officers, and observations were conducted during field data collection in 2017. The results of the land cover analysis showed that forest covered 66% of the study area in 1991, and by 2017 it had decreased to 45.8%. Most households depend on wood from customary land forests for tobacco curing (69%) and brick burning (68%). Furthermore, 47.6% of the households have expanded their agriculture land by approximately 0.57 hectares during the past 15 years. The interview survey and the focus group discussion identified that the underlying driving factors towards these anthropogenic activities are: (a) population growth, (b) poverty, (c) expensive alternative building materials, (d) lack of awareness, (e) lack of resources, (f) lack of commitment from the tobacco companies, and (g) market system of the cash crops grown in the area. In conclusion, a set of economic, institutional, social, and demographic factors, which are associated with imbalanced relationship between rural and urban areas, underpin agriculture expansion, tobacco growing, and brick burning, and have thereby contributed to the decline of the forest cover in Mwazisi, Malawi.
Entropic Analysis of Mirror Symmetry Breaking in Chiral Hypercycles
Authors: Hochberg David , Ribó Josep M.
Published: March 2019

Replicators are fundamental to the origin of life and evolvability. Biology exhibits homochirality: only one of two enantiomers is used in proteins and nucleic acids. Thermodynamic studies of chemical replicators able to lead to homochirality shed valuable light on the origin of homochirality and life in conformity with the underlying mechanisms and constraints. In line with this framework, enantioselective hypercyclic replicators may lead to spontaneous mirror symmetry breaking (SMSB) without the need for additional heterochiral inhibition reactions, which can be an obstacle for the emergence of evolutionary selection properties. We analyze the entropy production of a two-replicator system subject to homochiral cross-catalysis which can undergo SMSB in an open-flow reactor. The entropy exchange with the environment is provided by the input and output matter flows, and is essential for balancing the entropy production at the non-equilibrium stationary states. The partial entropy contributions, associated with the individual elementary flux modes, as defined by stoichiometric network analysis (SNA), describe how the system’s internal currents evolve, maintaining the balance between entropy production and exchange, while minimizing the entropy production after the symmetry breaking transition. We validate the General Evolution Criterion, stating that the change in the chemical affinities proceeds in a way as to lower the value of the entropy production.
Effect of Micro- and Nano-Sized Carbonous Solid Lubricants as Oil Additives in Nanofluid on Tribological Properties
Authors: Omrani Emad , Menezes Pradeep L. , Rohatgi Pradeep K.
Published: March 2019

The tribological behavior of graphene and graphite as additives in canola oil was investigated with a pin-on-disk tribometer. The wear surfaces of the aluminum pins lubricated with the additive-containing canola oil were analyzed by scanning electron microscopy (SEM). It was found that graphene and graphite as additives in oil show a lower coefficient of friction and wear rate in comparison with neat canola oil. The graphene sheets are more effective than graphite flakes to reduce friction and wear. In addition, there is a proper concentration where the coefficient of friction (COF) and wear are in minimum value. The optimal concentration of the additive in canola oil is about 0.7 wt %. Therefore, the load-carrying capacity and antiwear ability of the lubricating oil are improved. Moreover, the worn surface of aluminum pins is smother in the presence of solid lubricant rather than neat oil.
Unsaturated Poly(Hydroxyalkanoates) for the Production of Nanoparticles and the Effect of Cross-Linking on Nanoparticle Features
Authors: Pignatello Rosario , Impallomeni Giuseppe , Cupri Sarha , Puzzo Giuseppe , Curcio Claudia , Rizzo Maria Giovanna , Guglielmino Salvatore , Ballistreri Alberto
Published: March 2019

A biodegradable poly(3-R-hydroxyalkanoate) synthesized by Pseudomonas mediterranea was investigated as a biomaterial to obtain colloidal drug delivery systems. Using a nanoprecipitation method, nanoparticles with a mean size of 155 nm and a negative surface charge were formed. They can be freeze-dried by adding hydroxypropyl-β-cyclodextrin as a cryoprotectant, and they have been shown to efficiently load both a hydrophilic (calcein) and a lipophilic (Nile red) model probe. Since this polymer contains terminal double bonds in the side chains, cross-linking conditions were tested. In particular, under the action of UV rays or irradiation with an incandescent yellow lamp, this polymer tended to cross-link.
Defect Creation in the Root of Single-Crystalline Turbine Blades Made of Ni-Based Superalloy
Authors: Krawczyk Jacek , Paszkowski Robert , Bogdanowicz Włodzimierz , Hanc-Kuczkowska Aneta , Sieniawski Jan , Terlecki Bartosz
Published: March 2019

An analysis of the defects in the vicinity of the selector–root connection plane occurring during the creation of single-crystalline turbine blades made of CMSX-6 Ni-based superalloy was performed. X-ray diffraction topography, scanning electron microscopy, and positron annihilation lifetime spectroscopy were used. Comparing the area of undisturbed axial growth of dendrites to the area of lateral growth concluded that the low-angle boundaries-like (LAB-like) defects were created in the root as a result of unsteady-state lateral growth of some secondary dendrite arms in layers of the root located directly at the selector–root connection plane. Additional macroscopic low-angle boundaries (LABs) with higher misorientation angles were created as a result of concave curvatures of liquidus isotherm in platform-like regions near selector–root connections. Two kinds of vacancy-type defects, mono-vacancies and vacancy clusters, were determined in relation to the LABs and LAB-like defects. Only mono-vacancies appeared in the areas of undisturbed axial growth. Reasons for the creation of macroscopic LABs and LAB-like defects, and their relationships with vacancy-type defects were discussed.
Dealing with Nap-Core Sandwich Composites: How to Predict the Effect of Symmetry
Authors: Ha Giap , Zehn Manfred , Marinkovic Dragan , Fragassa Cristiano
Published: March 2019

The behavior of nap-core sandwiches was investigated with a special focus on the effect of symmetry in nap cores. A nap-core is, in general terms, a 3D-formed hollow structure made of knitted textile impregnated by a thermosetting resin. The molding process determines if the nap-core is double-sided (symmetric) or single-sided. The sandwich with nap-core owns various remarkable properties of a novel lightweight material, but the nap-core’s complex structure makes the prediction of these properties a difficult task. While the analysis of a single-sided nap-core sandwich has been presented by the authors before, this study is focused on the simulation of symmetric nap-core sandwich. Overall, performance of the structure is examined with respect to several loading conditions. The simulation approach invokes a typical homogenization scheme to find the engineering properties of the nap-core’s fabric with least computational time and memory resources. Results from experiments and simulations exhibit a good compatibility, which prove the fitness of the modeling method.
Metal Oxide Thin Films Prepared by Magnetron Sputtering Technology for Volatile Organic Compound Detection in the Microwave Frequency Range
Authors: Rydosz Artur , Brudnik Andrzej , Staszek Kamil
Published: March 2019

Metal oxide thin films such as copper oxide, titanium dioxide, and tin dioxide deposited by magnetron sputtering technology were verified as a gas-sensitive layer in microwave-based gas sensors operated at 2.4 GHz. The developed gas sensors were tested at room temperature (23 °C) and 50% relative humidity (RH) under exposure to 0–200 ppm of selected volatile organic compounds (acetone, ethanol, and methanol) that are of high interest in industry and biomedical applications. The highest responses to acetone were obtained for CuO-based gas sensors, to ethanol for SnO2-based gas sensors, while for methanol detection both dioxides, SnO2 and TiO2, exhibited good sensitivity.
Combustion Synthesis of Non-Precious CuO-CeO2 Nanocrystalline Catalysts with Enhanced Catalytic Activity for Methane Oxidation
Authors: Zedan Abdallah F. , AlJaber Amina S.
Published: March 2019

In this study, xCuO-CeO2 mixed oxide catalysts (Cu weight ratio x = 1.5, 3, 4.5, 6 and 15 wt.%) were prepared using solution combustion synthesis (SCS) and their catalytic activities towards the methane (CH4) oxidation reaction were studied. The combustion synthesis of the pure CeO2 and the CuO-CeO2 solid solution catalysts was performed using copper and/or cerium nitrate salt as an oxidizer and citric acid as a fuel. A variety of standard techniques, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were employed to reveal the microstructural, crystal, thermal and electronic properties that may affect the performance of CH4 oxidation. The CuO subphase was detected in the prepared solid solution and confirmed with XRD and Raman spectroscopy, as indicated by the XRD peaks at diffraction angles of 35.3° and 38.5° and the Ag Raman mode at 289 cm−1, which are characteristics of tenorite CuO. A profound influence of Cu content was evident, not only affecting the structural and electronic properties of the catalysts, but also the performance of catalysts in the CH4 oxidation. The presence of Cu in the CeO2 lattice obviously promoted its catalytic activity for CH4 catalytic oxidation. Among the prepared catalysts, the 6% CuO-CeO2 catalyst demonstrated the highest performance, with T50 = 502 °C and T80 = 556 °C, an activity that is associated with the availability of a fine porous structure and the enhanced surface area of this catalyst. The results demonstrate that nanocrystalline copper-ceria mixed oxide catalysts could serve as an inexpensive and active material for CH4 combustion.
Preparation of Sludge-Derived Activated Carbon by Fenton Activation and the Adsorption of Eriochrome Black T
Authors: Wen Haifeng , Zhang Daofang , Gu Lin , Yu Haixiang , Pan Minmin , Huang Yuanxing
Published: March 2019

Sludge-derived activated carbon (SAC) was prepared by Fenton activation and calcination, and used as adsorbent to eliminate Eriochrome Black T (EBT) dye from aqueous media. The characterization results indicated that the produced SAC had a porous structure, high specific surface area, and abundant functional groups on its surface. The adsorption process was affected by pH, adsorbent dosage, time, and temperature. The adsorption capacity increased with temperature, and the highest adsorption capacity reached 178.2 mg·g−1 in 48 h at 318 K and pH 6. The results of the adsorption isotherm, kinetic, and thermodynamic analyses revealed that the adsorption of EBT onto SAC was naturally endothermic and spontaneous, involved both physical and chemical processes, and belonged mostly to the multilayer type of adsorption.
Medical-Grade PCL Based Polyurethane System for FDM 3D Printing—Characterization and Fabrication
Authors: Haryńska Agnieszka , Kucinska-Lipka Justyna , Sulowska Agnieszka , Gubanska Iga , Kostrzewa Marcin , Janik Helena
Published: March 2019

The widespread use of three-dimensional (3D) printing technologies in medicine has contributed to the increased demand for 3D printing materials. In addition, new printing materials that are appearing in the industry do not provide a detailed material characterization. In this paper, we present the synthesis and characterization of polycaprolactone (PCL) based medical-grade thermoplastic polyurethanes, which are suitable for forming in a filament that is dedicated to Fused Deposition Modeling 3D (FDM 3D)printers. For this purpose, we synthesized polyurethane that is based on PCL and 1,6-hexamethylene diisocyanate (HDI) with a different isocyanate index NCO:OH (0.9:1, 1.1:1). Particular characteristics of synthesized materials included, structural properties (FTIR, Raman), thermal (differential scanning calorimetry (DSC), thermogravimetric analysis (TGA)), mechanical and surfaces (contact angle) properties. Moreover, pre-biological tests in vitro and degradation studies were also performed. On the basis of the conducted tests, a material with more desirable properties S-TPU(PCL)0.9 was selected and the optimization of filament forming via melt-extrusion process was described. The initial biological test showed the biocompatibility of synthesized S-TPU(PCL)0.9 with respect to C2C12 cells. It was noticed that the process of thermoplastic polyurethanes (TPU) filaments forming by extrusion was significantly influenced by the appropriate ratio between the temperature profile, rotation speed, and dosage ratio.
Characterization of the Mechanical Properties of FFF Structures and Materials: A Review on the Experimental, Computational and Theoretical Approaches
Authors: Cuan-Urquizo Enrique , Barocio Eduardo , Tejada-Ortigoza Viridiana , Pipes R. Byron , Rodriguez Ciro A. , Roman-Flores Armando
Published: March 2019

The increase in accessibility of fused filament fabrication (FFF) machines has inspired the scientific community to work towards the understanding of the structural performance of components fabricated with this technology. Numerous attempts to characterize and to estimate the mechanical properties of structures fabricated with FFF have been reported in the literature. Experimental characterization of printed components has been reported extensively. However, few attempts have been made to predict properties of printed structures with computational models, and a lot less work with analytical approximations. As a result, a thorough review of reported experimental characterization and predictive models is presented with the aim of summarizing applicability and limitations of those approaches. Finally, recommendations on practices for characterizing printed materials are given and areas that deserve further research are proposed.
Study on the Properties of Vertical Carbon Nanotube Films Grown on Stainless Steel Bipolar Plates
Authors: Lu Congda , Shi Fengye , Jin Jing , Peng Xiang
Published: March 2019

Research on the conductivity and corrosion resistance of stainless steel bipolar plates in a proton exchange membrane fuel cell (PEMFC) is commonly performed in a normal-temperature environment (about 20 °C). However, these fuel cells must function in low-temperature environments (lower than 0 °C) in some conditions, such as in vehicle fuel cells and in portable power supplies that operate during the winter in northern China. Stainless steel bipolar plates have higher requirements in terms of their hydrophobic and anti-icing properties, in addition to needing high conductivity and corrosion resistance. In this study, carbon nanotubes (CNTs) are grown on the surface of 304 stainless steel (304 SS) without a catalyst coating by plasma-enhanced chemical vapor deposition (PECVD), which is a simple and cheap method that allows stainless steel to be used as bipolar plates in low-temperature environments. The Raman spectroscopy and scanning electron microscopy (SEM) results show that the CNTs grown on the surface of 304 SS have different morphologies. The stainless steel samples with different CNT morphologies are tested by hydrophobicity and in situ icing experiments to prove that vertical CNTs can achieve a superhydrophobic state and have good anti-icing properties. The interfacial contact resistance (ICR) of the bare 304 SS and the 304 SS with vertical CNTs is compared by voltammetry, and then the corrosion resistances of both types is compared in a simulated PEMFC environment via a three-electrode system. Consequently, the ICR of the 304 SS with vertical CNTs was lower than the bare 304 SS. The corrosion potential was positive, and the corrosion current density was greatly reduced for the stainless steel with vertical CNTs grown directly on its surface when compared with the bare 304 SS. The experimental results show that vertical CNTs have good application prospects as bipolar plates for PEMFCs in low-temperature environments.
Correlation of Macroscopic Fracture Behavior with Microscopic Fracture Mechanism for AHSS Sheet
Authors: Qian Lingyun , Wang Xiaocan , Sun Chaoyang , Dai Anyi
Published: March 2019

This research aims to correlate the macroscopic fracture phenomenon with its microscopic fracture mechanism for an advanced high-strength steel (AHSS) TRIP 780 sheet by applying a combined experimental-numerical approach. Six specimens with different shapes were tensioned to fracture and the main deformation areas of specimens were subjected to stress states ranging from lower to higher stress triaxiality. The final fracture surface feature for each specimen was obtained to characterize the macroscopic fracture modes at different stress states. The scanning electron microscope (SEM) fractographies of fracture surfaces were detected to reveal the microscopic fracture mechanisms. The stress triaxiality evolution was applied to correlate of fracture mode and fracture mechanism by comparing the macroscopic fracture features as well as micro-defect changes. An increase of stress triaxiality leads to voids extension and then results in a voids-dominant fracture. The micro-shear-slip tends to appear in the stress triaxiality level lower than that of pure shear stress state. The fracture behavior of a practice deformation process was the result of interplay between shear-slip fracture and void-dominant fracture. The unified relationship between average void sizes and stress triaxiality was obtained. The void growth was predicted by the Rice–Tracey model with higher precision.
Synthesis of Nanocrystalline AZ91 Magnesium Alloy Dispersed with 15 vol.% Submicron SiC Particles by Mechanical Milling
Authors: Su Shitian , Zhou Jixue , Tang Shouqiu , Yu Huan , Su Qian , Zhang Suqing
Published: March 2019

The development of a magnesium matrix composite with a high content of dispersions using conventional liquid-phase process is a great challenge, especially for nanometer/submicron particles. In this work, mechanical milling was employed to prepare nanocrystalline AZ91 dispersed with 15 vol.% submicron SiC particles (SiCp/AZ91). AZ91 with no SiCp was applied as a comparative study with the same mechanical milling. In order to investigate the mechanism of dispersing, the morphology evolution of powders and the corresponding SiCp distribution were observed. As the scanning electron microscope (SEM) analysis exhibited, the addition of SiCp accelerated the smashing of AZ91 particles, which promoted the dispersion of SiCp in AZ91. Thus, after mechanical milling, 15 vol.% SiCp, which was smashed from 800 to 255 nm, got uniformly distributed in the Mg matrix. Based on X-ray diffraction (XRD) results, part of the Mg17Al12 precipitate got dissolved, and an Al-supersaturated Mg solid solution was formed. The transmission electron microscopy (TEM) results showed that the ultimate Mg grain (32 nm) of milled SiCp/AZ91 was much smaller than that of milled AZ91 (64 nm), which can be attributed to a pinning effect of submicron SiCp. After mechanical milling, the hardness of SiCp/AZ91 reached 185 HV, which was 185% higher than the original AZ91 and 33% higher than milled AZ91, due to fine Mg grain and submicron dispersions.
New Antimalarial and Antimicrobial Tryptamine Derivatives from the Marine Sponge Fascaplysinopsis reticulata
Authors: Campos Pierre-Eric , Pichon Emmanuel , Moriou Céline , Clerc Patricia , Trépos Rozenn , Frederich Michel , De Voogd Nicole , Hellio Claire , Gauvin-Bialecki Anne , Al-Mourabit Ali
Published: March 2019

Chemical study of the CH2Cl2-MeOH (1:1) extract of the sponge Fascaplysinopsis reticulata collected in Mayotte highlighted three new tryptophan derived alkaloids, 6,6′-bis-(debromo)-gelliusine F (1), 6-bromo-8,1′-dihydro-isoplysin A (2) and 5,6-dibromo-8,1′-dihydro-isoplysin A (3), along with the synthetically known 8-oxo-tryptamine (4) and the three known molecules from the same family, tryptamine (5), (E)-6-bromo-2′-demethyl-3′-N-methylaplysinopsin (6) and (Z)-6-bromo-2′-demethyl-3′-N-methylaplysinopsin (7). Their structures were elucidated by 1D and 2D NMR spectra and HRESIMS data. All compounds were evaluated for their antimicrobial and their antiplasmodial activities. Regarding antimicrobial activities, the best compounds are (2) and (3), with minimum inhibitory concentration (MIC) of 0.01 and 1 µg/mL, respectively, towards Vibrio natrigens, and (5), with MIC values of 1 µg/mL towards Vibrio carchariae. In addition the known 8-oxo-tryptamine (4) and the mixture of the (E)-6-bromo-2′-demethyl-3′-N-methylaplysinopsin (6) and (Z)-6-bromo-2′-demethyl-3′-N-methylaplysinopsin (7) showed moderate antiplasmodial activity against Plasmodium falciparum with IC50 values of 8.8 and 8.0 µg/mL, respectively.