bluuebunny/crossref_metadata_2025 huggingface dataset:
Bonding in Phosphanylphosphinidene Complexes of Transition Metals and their Correlation with Structures, 31P NMR Spectra, and Reactivities
Authors: Zauliczny Mateusz , Ordyszewska Anna , Pikies Jerzy , Grubba Rafał
Published: May 2018

Theoretical studies of the bonding interactions and most important properties are carried out for isolable phosphanylphosphinidene complexes of transition metals. Three main types of phosphanylphosphinidene complexes are distinguished, based on the way in which the phosphanylphosphinidene ligand bonds to the metal center: (i) side‐on complexes of platinum, where the R2Pβ–Pα ligand mimics structural features of free singlet phosphanylphosphinidenes with short, polarized, double P–P bonds and two lone electron pairs on the terminal P atom. In this case, interactions between the platinum center and the phosphanylphosphinidene ligand are determined by π(PP)→s(Pt) donation and d(Pt)→π*(PP) back‐donation; (ii) terminal and bridging complexes of zirconium, where the R2P–P ligand is bonded to the metal center only by the terminal P atom. The metal–ligand interactions are a result of the singly occupied p orbitals of a terminal P atom overlapping with the singly occupied d orbitals of the Zr atom, which leads to multiple bonding; (iii) side‐on complexes of early transition metals, where the R2Pβ–Pα group is bonded to the metal through an R2Pβ–M single bond and a Pα=M double bond. The observed shortening of the P–P bond in these complexes is explained by a negative hyperconjugation, as a result of the interaction of the π(PαM) orbital with the σ*(PβC) orbitals.
A hybrid pressure‐based solver for nonideal single‐phase fluid flows at all speeds
Authors: Kraposhin Matvey V. , Banholzer Matthias , Pfitzner Michael , Marchevsky Ilia K.
Published: May 2018

This paper describes the implementation of a numerical solver that is capable of simulating compressible flows of nonideal single‐phase fluids. The proposed method can be applied to arbitrary equations of state and is suitable for all Mach numbers. The pressure‐based solver uses the operator‐splitting technique and is based on the PISO/SIMPLE algorithm: the density, velocity, and temperature fields are predicted by solving the linearized versions of the balance equations using the convective fluxes from the previous iteration or time step. The overall mass continuity is ensured by solving the pressure equation derived from the continuity equation, the momentum equation, and the equation of state. Nonphysical oscillations of the numerical solution near discontinuities are damped using the Kurganov‐Tadmor/Kurganov‐Noelle‐Petrova (KT/KNP) scheme for convective fluxes. The solver was validated using different test cases, where analytical and/or numerical solutions are present or can be derived: (1) A convergent‐divergent nozzle with three different operating conditions; (2) the Riemann problem for the Peng‐Robinson equation of state; (3) the Riemann problem for the covolume equation of state; (4) the development of a laminar velocity profile in a circular pipe (also known as Poiseuille flow); (5) a laminar flow over a circular cylinder; (6) a subsonic flow over a backward‐facing step at low Reynolds numbers; (7) a transonic flow over the RAE 2822 airfoil; and (8) a supersonic flow around a blunt cylinder‐flare model. The spatial approximation order of the scheme is second order. The mesh convergence of the numerical solution was achieved for all cases. The accuracy order for highly compressible flows with discontinuities is close to first order and, for incompressible viscous flows, it is close to second order. The proposed solver is named rhoPimpleCentralFoam and is implemented in the open‐source CFD library OpenFOAM®. For high speed flows, it shows a similar behavior as the KT/KNP schemes (implemented as rhoCentralFoam‐solver, Int. J. Numer. Meth. Fluids 2010), and for flows with small Mach numbers, it behaves like solvers that are based on the PISO/SIMPLE algorithm.
Land cover controls on depression‐focused recharge on the Oak Ridges Moraine, southern Ontario, Canada
Authors: Greenwood Wes J. , Buttle James M.
Published: May 2018

The Oak Ridges Moraine (ORM) is a key hydrogeologic feature in southern Ontario. Previous research has emphasized the importance of depression‐focused recharge (DFR) for the timing and location of water recharge to the ORM's aquifers. However, the significance of DFR has not been empirically demonstrated, and the ORM's permeable surficial deposits imply that rainfall and snowmelt will largely recharge vertically rather than move laterally to topographic depressions. The exception may be during winter and spring, when concrete soil frost limits infiltration and encourages overland flow. The potential for DFR was examined for closed depressions under forest and agricultural land covers with similar soils and surficial geology. Air temperatures, precipitation, snow depth and water equivalent, soil water contents, soil freezing, and depression surface‐water levels were monitored during the winter and spring of 2012–2013 and 2013–2014. Recharge (R) was estimated at the crest and base of each depression using a 1‐dimensional water balance approach and surface‐applied Br− tracing. Both forest and agricultural land covers experienced soil freezing; however, forest soils did not develop concrete frost. Conversely, agricultural fields saw concrete frost, overland flow, episodic ponding, and subsequent drainage of rain‐on‐snow and snowmelt inputs in open depressions. Recharge at the base of open depressions exceeded that in surrounding areas by an order of magnitude, suggesting that DFR is a significant hydrologic process during winter and spring under agricultural land cover on the ORM. Closed topographic depressions under agricultural land cover on the ORM crest may serve as critical recharge “hot spots” during winter and spring, and the ability of the unsaturated zone beneath these depressions to modify the chemistry of recharging water deserves further attention.
Gold(I)‐Catalysis for the Synthesis of Terpenoids: From Intramolecular Cascades to Intermolecular Cycloadditions
Authors: Mayans Joan Guillem , Armengol‐Relats Helena , Calleja Pilar , Echavarren Antonio M.
Published: May 2018

Gold(I)‐catalyzed cycloisomerizations of 1,n‐enynes proceed through electrophilic intermediates that can be trapped intra‐ or intermolecularly by a variety of hetero‐ and carbon nucleophiles to form complex skeletons in a single step. This review covers the efforts of our group towards the development of new reactions that have been successfully applied in the total synthesis of several natural terpenoids and related carbocyclic structures, as well as for the ready access to challenging linear acenes.
The association of the placental CASPASE‐3 gene polymorphisms and preeclampsia susceptibility and in‐silico analysis
Authors: Teimoori Batool , Yazdi Atefeh , Rezaei Mahnaz , Mohammadpour‐Gharehbagh Abbas , Jahantigh Danial , Salimi Saeedeh
Published: May 2018

Preeclampsia is a pathologic complication of pregnancy, associated with increased apoptosis in the cytotrophoblasts as the main cause of this disorder. Caspase‐3 is a key apoptosis‐related enzyme that both mitochondrial and death receptor apoptotic pathways can activate. In this study, we aimed to investigate the effect of placental CASP‐3 rs4647602 and rs4647610 polymorphisms on PE susceptibility. The placentas of 106 PE women and 115 normotensive pregnant women were collected. Genomic DNA was extracted from the placenta. For genotyping of CASP‐3 rs4647602 and rs4647610 polymorphisms, polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) was used. The frequencies of placental CASP‐3rs4647602CA and rs4647610GA genotypes were higher in PE women; however, the differences were not statistically different (P = 0.36 and P = 0.13, respectively). In addition, the frequencies of CA‐GA combined genotypes and A‐A haplotype were higher in PE women compared to the control women; however, the differences were marginally non‐significant (P = 0.051 and P = 0.08, respectively). In‐silico analysis revealed new enhancer and silencer motifs for mutant alleles of CASP‐3rs4647602 and rs4647610 polymorphisms. In conclusion, placental CASP‐3rs4647602 and rs4647610 polymorphisms were not associated with PE. Further studies with higher sample size are necessary to confirm or refute these findings.
Retracted: Long non‐coding RNA GAS5 aggravates hypoxia injury in PC‐12 cells via down‐regulating miR‐124
Authors: Hu Xiaoli , Liu Juan , Zhao Gang , Zheng Jiaping , Qin Xia
Published: May 2018

One important feature of cerebral ischemia is hypoxia injury in nerve cells. Growth arrest‐specific transcript 5 (GAS5) is widely reported as a tumor suppressor gene; however, the investigations about its role in cerebrovascular disease are relatively rare. This study was aimed to explore the impact of GAS5 on hypoxia response in nervous cells. PC‐12 cells were incubated under anoxic condition to induce hypoxia injury. Regulatory effects of GAS5 on miR‐124 and miR‐124 on ICAM‐1 expression were assessed by qRT‐PCR and/or Western blot. Targeting effect of miR‐124 on ICAM‐1 3′‐untranslated regions (UTR) was evaluated through dual luciferase activity assay. The potential regulatory mechanism on hypoxia injury in PC‐12 cells was assessed by detecting key elements of NF‐κB and Notch signaling pathways using Western blot. GAS5 ectopic expression accentuated hypoxia injury in PC‐12 cells. miR‐124 expression was negatively regulated by GAS5 expression. Cells with overexpressions of GAS5 and miR‐124 alleviated hypoxia injury as in compassion with cells only with GAS5 overexpression. ICAM‐1 expression was negatively regulated by miR‐124 expression. ICAM‐1 was a functional target of miR‐124. ICAM‐1 overexpression aggravated hypoxia injury, but inversely, ICAM‐1 silence diminished hypoxia damage. Besides, ICAM‐1 expression was negatively related with activation of NF‐κB and Notch pathways. GAS5‐miR‐124‐ICAM‐1 axis could regulate hypoxia injury in PC‐12 cells. GAS5 might aggravate hypoxia injury via down‐regulating miR‐124, then up‐regulating ICAM‐1, and further enhancing activations of NF‐κB and Notch pathways.
Bisphenol A (BPA) binding on full‐length architectures of estrogen receptor
Authors: Liu Yaquan , Qu Kaili , Hai Ying , Zhao Chunyan
Published: May 2018

Previous research has shown that the major toxicity mechanism for many environment chemicals is binding with estrogen receptor (ER) and blocking endogenous estrogen access, including bisphenol A (BPA). However, the molecular level understanding the global consequence of BPA binding on the full‐length architectures of ER is largely unknown, which is a necessary stage to evaluate estrogen‐like toxicity of BPA. In the present work, the consequence of BPA on full‐length architectures of ER was firstly modeled based on molecular dynamics, focusing on the cross communication between multi‐domains including ligand binding domain (LBD) and DNA binding domain (DBD). The study proved consequence of BPA upon full‐length ER structure was dependent on long‐range communications between multiple protein domains. The allosteric effects occurring in LBD units could alter dimerization formation through a crucial change in residue‐residue connections, which resulted in relaxation of DBD. It indicated BPA could present consequence on the full‐size receptor, not only on the separate domains, but also on the cross communication among LBD, DBD, and DNA molecules. It might provide detailed insight into the knowledge about the structural characteristics of ER and its role in gene regulation, which eventually helped us evaluate the estrogen‐like toxicity upon BPA binding with full‐length ER.
The role of Nrf2 transcription factor in viral infection
Authors: Ramezani Ali , Nahad Mehdi Parsa , Faghihloo Ebrahim
Published: May 2018

The nuclear factor erythroid 2 related factor 2 (Nrf2) is a major regulator of intracellular inducible defense systems against harmful endogenous and exogenous substances in the body. Under normal conditions Nrf2 is mainly binds to keap1 and located in the cytoplasm. However, in response to oxidative and electrophile stress, Nrf2 translocated to the nucleus and link to anti‐oxidant response elements to induce the transcription of cytoprotective genes. Most viruses cause oxidative stress and increase the activity of radicals and reactive oxygen species (ROS), subsequently, the cellular protection system activates the Nrf2 and increases the expression of cytoprotective genes. However, in some cases, the activation of Nrf2 is not ROS‐dependent, and is carried out directly via the ROS‐independent pathway. Many viruses cause the activation of Nrf2, which is involved in the pathogenesis and the progression of the virus infection and even in its chronic form. However, some viruses inhibit the activation of Nrf2, in which case the virus also benefits of this mechanism to maintain the homeostasis of the cell. However, the challenge between the Nrf2/ARE signaling pathway of and viral infections is unknown in some cases, and in order to know more details in this regard, a more detailed seems necessary.
MicroRNA expression in cervical cancer: Novel diagnostic and prognostic biomarkers
Authors: Gao Chundi , Zhou Chao , Zhuang Jing , Liu Lijuan , Liu Cun , Li Huayao , Liu Gongxi , Wei Junyu , Sun Changgang
Published: May 2018

Growing evidence has shown that a large number of miRNAs are abnormally expressed in cervical cancer (CC) tissues and play irreplaceable roles in tumorigenesis, progression, and metastasis. This study aimed to identify new biomarkers and pivotal genes associated with CC prognosis through comprehensive bioinformatics analysis. At first, the data of gene expression microarray (GSE30656) was downloaded from GEO database and differential miRNAs were obtained. Additionally, 4 miRNAs associated with the survival time of patients with CC were screened through TCGA differential data analysis, Kaplan‐Meier, and Landmark analysis. Among them, the low expression of miR‐188 and high expression of miR‐223 correlated with the short survival of CC patients, while the down‐regulation of miR‐99a and miR‐125b was closely related to the 5‐year survival rate of patients. Then, based on the correspondence between the differentially expressed genes (DEGs) in CC from the TCGA data and the 4 miRNAs target genes, 58 target genes were screened to perform the analysis of function enrichment and the visualization of protein‐protein interaction (PPI) networks. The seven pivotal genes of the PPI network as the target genes of four miRNAs related to prognosis, they were directly or indirectly involved in the development of CC. In this study, based on high‐throughput data mining, differentially expressed miRNAs and related target genes were analyzed to provide an effective bioinformatics basis for further understanding of the pathogenesis and prognosis of CC. And the results may be a promising biomarker for the early screening of high‐risk populations and early diagnosis of cervical cancer.
In situ synthesis of C3N4/Bi2S3 composites with enhanced photocatalytic degradation performance under visible light irradiation
Authors: Yin Jian , Wu Zhenyu , Fang Min , Xu Ying , Zhu Weiju , Li Cun
Published: May 2018

Carbon nitride/bismuth sulfide (C3N4/Bi2S3) nanocomposites were prepared by a facile one‐step in situ calcination method using ammonium thiocyanate and bismuth chloride as reagents. The crystal structure, composition, and morphology of the nanocomposites were characterized by X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The photocatalytic degradation of rhodamine B (RhB) was carried out to evaluate the photocatalytic activity of the nanocomposites under visible light irradiation. The as‐prepared C3N4/Bi2S3 nanocomposites displayed enhanced visible light absorption. These photocatalysts exhibited superior photodegradation performance under visible light irradiation compared to pure C3N4. Meanwhile, the C3N4/Bi2S3 nanocomposites exhibited remarkably stable photocatalytic efficiency after five cycles of photodegradation of RhB. The C3N4/Bi2S3 heterostructure improved the separation and transfer efficiency of the photogenerated electron–hole pairs. It played an important role for the enhanced photocatalytic performance of the nanocomposite photocatalysts.
Easy synthesis of three‐dimensionally ordered macroporous CuO–CeO2 mixed oxide catalysts and their high activities for the catalytic combustion of soot
Authors: Wang Yujie , Zhao Huawang , Zheng Jiandong , Chen Gangling , Yang Jing , Xu Jie
Published: May 2018

Three‐dimensionally ordered macroporous (3DOM) CuxCe‐M (x denote the mole ratio of Cu/[Ce + Cu]) oxide catalysts with large pore sizes and interconnected macroporous frameworks were successfully synthesized using a polymethyl methacrylate template method. The 3DOM structure improves the contact efficiency between catalyst and soot, which benefits soot elimination in the low temperature range. The low redox barriers of the 3DOM Cu–Ce solid solution also facilitate the elimination of the soot. The 3DOM Cu0.1Ce catalysts exhibit the highest catalytic activity with maximum soot oxidation rate temperatures at 375 and 351 °C in the air and NO
x atmosphere, respectively. The NO
x‐TPD results demonstrate that the NO2 produced in the Ce0.1Cu‐M sample plays a curial role in improving the soot oxidation performance. Meanwhile, the NO‐DRIFTs reveal that the nitrates stored in the Cu0.1Ce‐M sample also had a promotional effect on the soot elimination.
Regioselective Synthesis and Antibacterial Activity Studies of 1,2,3‐Triazol‐4‐YL]‐4‐methyl‐2H‐chromen‐2‐ones
Authors: Kolichala Niranjan , Thummala Bhupalreddy , Karkala Vasantha Kumar Pai
Published: May 2018

Synthesis, spectral analysis, and antibacterial activity of new coumarin derivatives are described in this paper. Twelve new coumarin derivatives were synthesized in moderate to good yields by the react with 4‐methyl‐6‐(prop‐2‐ynyloxy)‐2H‐chromen‐2‐one (3a–c) and ethyl azide (4a–l) and done by the click reaction to obtained 6‐[(l‐ethyl‐lH‐l,2,3‐triazol‐4‐yl)methoxy]‐4‐methyl‐2H‐chromen‐2‐ones (5a–l). The structures of all the newly synthesized molecules were assigned by elemental analysis and spectral data. The synthesized compounds were screened for their antibacterial activities strains using Cup plate method.
Influence of selenite and selenate on growth, leaf physiology and antioxidant defense system in wheat (Triticum aestivum L.)
Authors: Kaur Manpreet , Sharma Sucheta
Published: May 2018

BACKGROUND

Selenium (Se) induced oxidative stress as well as synthesis of non‐specific selenoproteins has been attributed to its toxicity in plants. Selenium toxicity can affect growth, chlorophyll and protein synthesis and crop yield. This study reveals the effects of different sources (sodium selenite and sodium selenate) and levels (2 and 4 mg Se kg−1 soil) of Se on its uptake, leaf physiology, antioxidant defense system, isoenzymic patterns and mitochondrial activity in wheat cultivar PBW621 at tillering and ear‐initiation stages.

RESULTS

Higher Se accumulation in leaves of wheat plants was observed in selenate than control and selenite treatments. Selenium tolerance index, chlorophyll, photosynthetic efficiency, mitochondrial reduction test, electron transport system activity, lipid peroxidation, proline and glutathione in Se‐treated wheat plants decreased significantly as compared to control. Significant increase in hydrogen peroxide and activities of antioxidant enzymes, namely catalase, peroxidase, superoxide dismutase, glutathione reductase in leaves was due to the presence of Se‐induced oxidative stress in wheat plants.

CONCLUSION

Wheat cultivar PBW621 could adapt to applied selenite concentrations by developing antioxidant defense system but selenate treated plants could exhibit toxicity tolerance up to 2 mg kg−1 and died at high concentrations due to damage to tissue development and function. © 2018 Society of Chemical Industry
Dynamic changes in polyphenol compounds, antioxidant activity, and PAL gene expression in different tissues of buckwheat during germination
Authors: Ling Ajing , Li Xiaoping , Hu Xinzhong , Ma Zhen , Wu Kunming , Zhang Huiwen , Hao Meng , Wei Sifan
Published: May 2018

BACKGROUND

There is a growing interest in buckwheat germination regarding the improvement of its health benefits. The aims of this study were to evaluate the effects of germination on polyphenol compounds, antioxidant activity, and phenylalanine ammonia‐lyase (PAL) gene expression in different tissues (cotyledon, hypocotyl, and radicle) of buckwheat sprouts during germination for 12 days, as well as to investigate their interactions.

RESULTS

Total polyphenol and total flavonoid contents, antioxidant activity, main polyphenol components, and PAL gene expression significantly increased during germination. On day 12, the rutin content in cotyledons was elevated to 88.6 g kg−1, which was 7.7‐times and 39.4‐times compared to those in buckwheat seeds and radicles, respectively. Meanwhile, chlorogenic acid in hypocotyls reached 7.84 g kg−1, which was 36.3‐fold higher than those in radicles. However, the PAL gene showed the highest expression in radicles.

CONCLUSION

Present results showed that polyphenol compounds mainly accumulated in cotyledons and hypocotyls. There was a negative correlation between polyphenol compounds and PAL gene expression. The discrepancy suggested that polyphenol compounds might experience transportation within buckwheat sprouts. The study could provide useful information for further application of buckwheat in functional foods, and revelation of the correlation between bioactive components and related gene expressions. © 2018 Society of Chemical Industry
Bridging the intention–behavior gap among organic grocery customers: The crucial role of point‐of‐sale information
Authors: Frank Phillip , Brock Christian
Published: May 2018

Although the interest in organic groceries has increased, actual buying behavior falls short for reasons that are mostly unknown to researchers and practitioners. This paper addresses this so‐called intention–behavior gap by investigating the impact of point‐of‐sale (POS) information on the perception of purchase barriers and behavior. While behavior and interest differ for various product categories, the organic groceries most frequently bought worldwide are differentiated on the basis of product category involvement in a pilot study. A laboratory experiment and a field experiment containing actual purchase behavior and market data revealed the possibility of enhancing organic purchases within low‐ and high‐involvement categories, while exposed to POS information. In low‐involvement product categories, POS information should reveal new product category‐specific organic features. In high‐involvement product categories, the perceived addition of value for money is crucial for purchasing organic groceries. While the effect of POS information on perceived trust and knowledge is higher for health conscious or green consumers in low‐involvement product categories, it is the converse in high‐involvement product categories.
The preference for scarcity: A developmental and comparative perspective
Authors: John Maria , Melis Alicia P. , Read Daniel , Rossano Federico , Tomasello Michael
Published: May 2018

Human adults often show a preference for scarce over abundant goods. In this paper, we investigate whether this preference was shared by 4‐ and 6‐year‐old children as well as chimpanzees, humans’ nearest primate relative. Neither chimpanzees nor 4‐year‐olds displayed a scarcity preference, but 6‐year‐olds did, especially in the presence of competitors. We conclude that scarcity preference is a human‐unique preference that develops as humans increase their cognitive skills and social experiences with peers and competitors. We explore different potential psychological explanations for scarcity preference and conclude scarcity preference is based on children's fear of missing out an opportunity, especially when dealing with uncertainty or goods of unknown value in the presence of competitors. Furthermore, the results are in line with studies showing that supply‐based scarcity increases the desirability of hedonic goods, suggesting that even as early as 6 years of age humans may use scarce goods to feel unique or special.
High Fat Diet Dysregulates Hypothalamic‐Pituitary Axis Gene Expression Levels which are Differentially Rescued by EPA and DHA Ethyl Esters
Authors: Shaikh Saame Raza , Shaver Patti R. , Shewchuk Brian M.
Published: May 2018

Scope

Dietary fat composition can modulate gene expression in peripheral tissues in obesity. Observations of the dysregulation of growth hormone (GH) in obesity indicate that these effects extend to the hypothalamic‐pituitary (H‐P) axis. The authors thus determine whether specific high fat (HF) diets influence the levels of Gh and other key gene transcripts in the H‐P axis.

Methods and results

C57BL/6 mice are fed a lean control diet or a HF diet in the absence or presence of OA, EPA, or DHA ethyl esters. Comparative studies are conducted with menhaden fish oil. The HF diet lowered pituitary Gh mRNA and protein levels, and cell culture studies reveal that elevated insulin and glucose can reduce Gh transcripts. Supplementation of the HF diet with OA, EPA, DHA, or menhaden fish oil do not improve pituitary Gh levels. The HF diet also impaired the levels of additional genes in the pituitary and hypothalamus, which are selectively rescued with EPA or DHA ethyl esters. The effects of EPA and DHA are more robust relative to fish oil.

Conclusion

A HF diet can affect H‐P axis transcription, which can be mitigated in some genes by EPA and DHA, but not fish oil in most cases.
Broadband and wide beamwidth circularly polarized antenna based on CRLH‐TL for navigation terminal applications
Authors: Luo Xin‐Shuai , Weng Zi‐bin , Wang Lei , Wang Feng , Lin Chen
Published: May 2018

A novel circularly polarized (CP) antenna with broadband and wide beamwidth for navigation terminal applications is presented in this article. A square patch with ring slots is adopted as radiator, which is fed by a Wilkinson power divider based on composite right‐/left‐handed transmission line (CRLH‐TL). The CP wave is produced by four linear polarized waves with equal amplitude but 90° phase shift. The proposed feeding network can provide stable phase shift in a wide bandwidth compared to the traditional power divider. Four Γ‐shaped parasitic branches are conducted to widen their 3 dB beamwidths which are raised to 100° at representative navigation frequencies. The size of the proposed antenna is 0.73λ0 × 0.73λ0 × 0.18λ0 (λ0 is the wavelength at center frequency in free space). The impedance bandwidth for VSWR < 2 is 83.61% and the 3 dB axial ratio (AR) bandwidth is 69.76%. Good agreement between simulated and measured results over the interested frequency bands is observed.
Balanced and unbalanced diplexers design using substrate integrated waveguide cavities
Authors: Ho Min‐Hua , Mimsyad Muhammad , Chang Geng‐Gui , Hong Yi‐Hao , Li Jen‐Chih , Hsu Chung‐I G.
Published: May 2018

The contribution of this article is to propose a balanced and unbalanced diplexers design using substrate integrated waveguide cavities (SIWCs). The employed SIWCs are square cavities which support two co‐frequency degenerate modes. A row of via‐holes is introduced inside the cavity to split the degenerate modes’ co‐frequency resonances into two frequency‐distinct ones, thus creating two duplexing bands with an auxiliary signal filtering effect. The fabricated diplexers performed quite well with measured and simulated results being in good agreement. The measured isolations between the two duplexing ports are more than 40 dB. Furthermore, the balanced SIWC diplexer has its measured common‐mode rejection levels >42 dB, and the measured common‐mode isolations between the two duplexing ports are >53 dB.
Design of a 220 GHz GaAs MHEMT push‐push VCO with low phase noise
Authors: Chen Huakang , Gao Bo , Gong Min , Lu Yuxi
Published: May 2018

In this paper, a negative‐resistance‐type push‐push voltage‐controlled‐oscillator (VCO) is proposed using a 0.07μm InAlAs/InGaAs MHEMT technology with ft of 300 GHz and fmax of 400 GHz. The Common‐gate structure of two sub‐oscillators shows more strong instability and excellent phase noise performance comparing with common‐source structure. And a strong second harmonic signal achieved −3 dBm of output power and −106 dBc/Hz@1 MHz offset of Phase noise at 220 GHz is generated by directly drain‐connecting and extremely simplified Output matching structure.
Compact wideband dual circularly polarized L‐shaped slot antenna
Authors: Wei Chen , Zhou Min , Ding Kang , Yu Fa‐Xin , Mo Jiong‐Jiong , Zhao Xiao‐Long
Published: May 2018

A wideband dual circularly polarized (CP) L‐shaped slot antenna with compact size is proposed. The antenna consists of an L‐shaped slot, two asymmetric microstrip feedlines and perturbed stub at the lower left corner of the slot. The initial L‐slot is used to obtain the first CP mode in lower band while the upper CP mode is realized by the orthogonal feedlines. Then, additional stub is also introduced to widen the axial ratio (AR) bandwidth. The proposed antenna with an area of 24 × 24 mm2 was fabricated and measured to demonstrate the final design. The L‐shaped slot antenna has a −10‐dB bandwidth of 97.9% (3.6‐10.5 GHz) and a 3‐dB AR bandwidth of 94.9%. In addition, the isolation is better than 12 dB within the CP band.
An arbitrary load selector with reconfigurable impedance matching for multiple antenna selection
Authors: Wei Kai , Lee Han Lim , Lee Moon‐Que
Published: May 2018

In this letter, an N‐way reconfigurable load selector for multiple antenna selection is presented based on switchable impedance matching network. The proposed structure is mainly configured by a 1:7 reconfigurable power divider as an arbitrary load selector and a switchable impedance matching circuitry. The arbitrary load selector has 1 input port and reconfigurable 7 output ports that any combination of output ports like single output or multiple outputs can be selected. Since the input impedance of load selector is varied according to the number of selected output ports, the reconfigurable impedance matching circuitry consisting of a reflection‐type phase shifter and a varactor diode compensates the impedance variation in different operation modes. The proposed structure was tested at 1.575 GHz for anti‐jamming controlled reception pattern antenna (CRPA) feed network where the reconfigurable impedance matching circuitry and switching elements were controlled by micro control unit. The experimental results showed that various path modes were selectable with return loss better than 25 dB and insertion loss <1.0 dB. Also, the magnitude variation in different mode was <0.6 dB.
Design of wide‐beam triple‐fed helical antennas employing simple and efficient feed networks for bandwidth improvement
Authors: Fartookzadeh Mahdi , Hossein Seyyed , Armaki Mohseni
Published: May 2018

In this article, a simple method for designing feed networks for wide‐beam multi‐fed helical antennas, suitable for satellite communications, is studied. Power division with similar phase differences for these antennas is obtained using serial feed network. The number of antenna arms is arbitrary, since the serial feed can be designed for any feasible number of outputs. Triple‐fed helical antenna is studied in this article, as an example. The proposed S band triple‐fed antenna benefits from 3 dB AR bandwidth of 24%. It has also low‐level reflection coefficients throughout the bandwidth.
Gain augmentation of a CPW fed printed miniature UWB antenna using frequency selective surface
Authors: Kundu Surajit
Published: May 2018

A co‐planar waveguide fed compact ultra‐wideband antenna is proposed in this article. The antenna dimension is reduced from 25 × 15 × 0.8 to 17.5 × 14.5 × 0.8 mm3 by lateral half cut of the radiating element. This miniature antenna gives a wide impedance bandwidth from 6 to 20.9 GHz with gain variation of 2‐4 dBi, average radiation efficiency of 85% and monopole like E‐plane and omnidirectional H‐plane pattern as per the experimental study. More than 3 dBi gain enhancement is achieved by adding dual frequency selective surfaces of dimension 17.5 × 17.5 mm2 each at the back side of antenna. The proposed antenna with frequency selective surface package provides more radiation to the broadside direction and an efficiency of >75%, without affecting the impedance band. Linear antenna transfer function and non‐varying group delay response are also reported.
A face‐centred finite volume method for second‐order elliptic problems
Authors: Sevilla Ruben , Giacomini Matteo , Huerta Antonio
Published: May 2018

This work proposes a novel finite volume paradigm, ie, the face‐centred finite volume (FCFV) method. Contrary to the popular vertex and cell‐centred finite volume methods, the novel FCFV defines the solution on the mesh faces (edges in two dimensions) to construct locally conservative numerical schemes. The idea of the FCFV method stems from a hybridisable discontinuous Galerkin formulation with constant degree of approximation, and thus inheriting the convergence properties of the classical hybridisable discontinuous Galerkin. The resulting FCFV features a global problem in terms of a piecewise constant function defined on the faces of the mesh. The solution and its gradient in each element are then recovered by solving a set of independent element‐by‐element problems. The mathematical formulation of FCFV for Poisson and Stokes equation is derived, and numerical evidence of optimal convergence in two dimensions and three dimensions is provided. Numerical examples are presented to illustrate the accuracy, efficiency, and robustness of the proposed methodology. The results show that, contrary to other finite volume methods, the accuracy of the FCFV method is not sensitive to mesh distortion and stretching. In addition, the FCFV method shows its better performance, accuracy, and robustness using simplicial elements, facilitating its application to problems involving complex geometries in three dimensions.
Crystal structure of a novel Kunitz type inhibitor, alocasin with anti‐Aedes aegypti activity targeting midgut proteases
Authors: Vajravijayan Senthilvadivel , Pletnev Sergei , Pletnev Vladimir Z , Nandhagopal Narayanasamy , Gunasekaran Krishnasamy
Published: May 2018

BACKGROUND

The pesticidal properties of many Kunitz‐type inhibitors have been reported previously; however, the mechanism of action is not well established. In this study, the activity of alocasin against Aedes aegypti is demonstrated and the structure–activity relationship of this Kunitz‐type inhibitor is explained through X‐ray structure analyses.

RESULTS

Alocasin was purified from mature rhizomes of Alocasia as a single polypeptide chain of ∼ 20 kDa. The structure at 2.5 Å resolution revealed a Kunitz‐type fold, but variation in the loop regions makes this structure unique; one loop with a single disulfide bridge is replaced by a long loop with two bridges. Alignment of homologous sequences revealed that this long loop contains a conserved Arg residue and modeling studies showed interaction with the catalytic Ser residue of trypsin‐like enzymes. The anti‐Aedes aegypti activity of alocasin is examined and discussed in detail. The in vitro activity of alocasin against midgut proteases of Aedes aegypti showed profound inhibition. Further, morphological changes in larvae upon treatment with alocasin revealed its activity against Ae. aegypti. Docking studies of alocasin with trypsin (5G1), a midgut protease involved in the development cycle and blood meal digestion, illustrated its insecticidal activity.

CONCLUSION

The three‐dimensional structure of alocasin was determined and its structure–function relationship established for its anti Ae. aegypti activity. © 2018 Society of Chemical Industry
Effect of elevated CO2 on the interaction between invasive thrips, Frankliniella occidentalis, and its host kidney bean, Phaseolus vulgaris
Authors: Qian Lei , He Shuqi , Liu Xiaowei , Huang Zujin , Chen Fajun , Gui Furong
Published: May 2018

BACKGROUND

Elevated CO2 can alter the leaf damage caused by insect herbivores. Frankliniella occidentalis (Pergande) is highly destructive invasive pest of crop production worldwide. To investigate how elevated CO2 affects F. occidentalis fed with Phaseolus vulgaris and, in particular, the interaction between plant defense and thrips anti‐defense, nutrient content and antioxidant enzyme activity of P. vulgaris were measured, as well as the detoxifying enzyme activity of adult thrips.

RESULTS

Elevated CO2 increased the soluble sugar, soluble protein and free amino acid content in non thrip‐infested plants, and decreased superoxide dismutase (SOD) and peroxidase (POD) activity in these plants. Feeding thrips reduced the nutrient content in plants, and increased their SOD, catalase and POD activity. Variations in nutrient content and antioxidant enzyme activity in plants showed an opposite tendency over thrip feeding time. After feeding, acetylcholinesterase, carboxylesterase, and mixed‐function oxidase activity in thrips increased to counter the plant defenses. Greater thrip densities induced stronger plant defenses and, in turn, detoxifying enzyme levels in thrips increased over thrip numbers.

CONCLUSION

Our study revealed that F. occidentalis can induce not only an antioxidant‐associated plant defense, but also detoxifying enzymes in thrips. Elevated CO2 might both enhance plant defense against thrip attack, and increase thrip anti‐defense against plant defenses. © 2018 Society of Chemical Industry
RNA‐Seq identification of candidate defense genes targeted by endophytic Bacillus cereus‐mediated induced systemic resistance against Meloidogyne incognita in tomato
Authors: Hu Haijing , Wang Cong , Li Xia , Tang Yunyun , Wang Yufang , Chen Shuanglin , Yan Shuzhen
Published: May 2018

BACKGROUND

The endophytic bacteria Bacillus cereus BCM2 has shown great potential as a defense against the parasitic nematode Meloidogyne incognita. Here, we studied endophytic bacteria‐mediated plant defense against M. incognita and searched for defense‐related candidate genes using RNA‐Seq.

RESULTS

The induced systemic resistance of BCM2 against M. incognita was tested using the split‐root method. Pre‐inoculated BCM2 on the inducer side was associated with a dramatic reduction in galls and egg masses on the responder side, but inoculated BCM2 alone did not produce the same effect. In order to investigate which plant defense‐related genes are specifically activated by BCM2, four RNA samples from tomato roots were sequenced, and four high‐quality total clean bases were obtained, ranging from 6.64 to 6.75 Gb, with an average of 21 558 total genes. The 34 candidate defense‐related genes were identified by pair‐wise comparison among libraries, representing the targets for BCM2 priming resistance against M. incognita. Functional characterization revealed that the plant–pathogen interaction pathway (ID: ko04626) was significantly enriched for BCM2‐mediated M. incognita resistance.

CONCLUSION

This study demonstrates that B. cereus BCM2 maintains a harmonious host–microbe relationship with tomato, but appeared to prime the plant, resulting in more vigorous defense response toward the infection nematode. © 2018 Society of Chemical Industry
Influence of mating disruption on the reproductive biology of the vine mealybug,Planococcus ficus(Hemiptera: Pseudococcidae), under field conditions
Authors: Cocco Arturo , Muscas Enrico , Mura Alessandra , Iodice Andrea , Savino Francesco , Lentini Andrea
Published: May 2018

BACKGROUND

Although mating disruption is increasingly being used to control the worldwide grapevine pest vine mealybug,Planococcus ficus(Signoret) (Hemiptera: Pseudococcidae), its mode of action remains unclear. A 3‐year field experiment was carried out to investigate the effects of mating disruption on the development and reproduction of the vine mealybug. The influence of mating disruption applied over consecutive years on the pest population density was also evaluated.

RESULTS

The percentage of ovipositing females was significantly reduced in disrupted plots by 18.8–66.2%, depending on the year. The absence of ovipositing females in disrupted plots in the autumn of the second and third years indicates the effectiveness of mating disruption throughout the whole growing season. Mating disruption consistently prolonged the pre‐oviposition period in all years by up to 12.5 days.

CONCLUSION

Our findings provide new insights into the mechanisms underlying the pheromone‐based control of the vine mealybug and indicate that the reduction of the pest population density is attributable to both a decrease and a delay in female mating. In addition, the population density of vine mealybugs under mating disruption decreased over the years, indicating that consecutive applications of this control strategy would significantly increase the effectiveness of control of the vine mealybug by mating disruption. © 2018 Society of Chemical Industry
Improving soil seed bank management
Authors: Haring Steven C , Flessner Michael L
Published: May 2018

Problems associated with simplified weed management motivate efforts for diversification. Integrated weed management uses the fundamentals of weed biology and applied ecology to provide a framework for diversified weed management programs; the soil seed bank comprises a necessary part of this framework. By targeting seeds, growers can inhibit the propagule pressure on which annual weeds depend for agricultural invasion. Some current management practices affect weed seed banks, such as crop rotation and tillage, but these tools are often used without specific intention to manage weed seeds. Difficulties quantifying the weed seed bank, understanding seed bank phenology, and linking seed banks to emerged weed communities challenge existing soil seed bank management practices. Improved seed bank quantification methods could include DNA profiling of the soil seed bank, mark and recapture, or 3D LIDAR mapping. Successful and sustainable soil seed bank management must constrain functionally diverse and changing weed communities. Harvest weed seed controls represent a step forward, but over‐reliance on this singular technique could make it short‐lived. Researchers must explore tools inspired by other pest management disciplines, such as gene drives or habitat modification for predatory organisms. Future weed seed bank management will combine multiple complementary practices that enhance diverse agroecosystems. © 2018 Society of Chemical Industry
Optical, Physical and Structural Properties of Er3+ Doped Low‐Phonon Energy Vitreous Matrix: ZnO‐B2O3‐TeO2
Authors: Chopra Neetu , Kaur Sandeep , Kaur Manpreet , Singla Shivani , Marwaha Ritika , Sharma Gopi , Heer Manmohan Singh
Published: May 2018

This paper reports on the effect of varying concentration of erbium (Er3+) on the (70‐x/2) TeO2 − (20‐x/2) B2O3 −10 ZnO − x Er2O3 (where x = 0, 0.5, 1.0, 2.0, 2.5 mol.%) system, fabricated using the conventional melt quenching technique. The impact of Er3+ on the structural, physical, and optical properties of these zinc borotellurite glasses is investigated using Fourier transform infrared spectroscopy (FTIR), density measurements and UV–vis spectroscopy. The amorphous nature is confirmed using X‐Ray diffraction. FTIR results reveal that the glass is formed of fundamental borate and tellurite network units. The addition of Er2­O3 results in the formation of TeO3 at the expense of Te‐O‐Te linkage. The UV–vis spectroscopy results show that Er3+ enter the glass matrix showing absorption peaks corresponding to 4f‐4f transitions of trivalent Erbium ions (Er3+) from ground state 4I15/2 to the excited states 4F5/2, 4F7/2, 2H11/2, 4S3/2, 4F9/2, 4I9/2, 4I11/2, and 4I13/2. The optical band gap tends to decrease and refractive index increases with the increase in Er3+ concentration hence making these materials more efficient for the optical devices such as light emitting devices and image sensors.
A discrete‐components millimeter‐wave satellite beacon receiver for Q‐band propagation experiment
Authors: Mrak Sebastijan , Hrovat Andrej , Vidmar Matjaz , Vilhar Andrej
Published: May 2018

Ever increasing bandwidth requirements in satellite communications continuously push the frequency limits. Q‐ band (33 – 50 GHz) is the next frequency band to be populated; however, at these frequencies, the Earth's troposphere (weather) profoundly alters the radio propagation conditions. Therefore, in order to properly plan radio links, accurate statistical models of radio channels are necessary. These statistical models are built upon empirical data, ie, measurements, which are furthermore used to design appropriate Propagation Impairment Mitigation Techniques. The Q‐ band lacks such data, hence the statistical models are inadequate. To address this problem, we propose a cost‐effective, easy to replicate Q‐ band beacon receiver to leverage the Alphasat propagation campaign. We present a step‐by‐step implementation process of the receiver's fundamental part, a Low‐Noise Block, which translates input 39.402 GHz signal into 162 MHz output signal with a conversion gain of 52 dB. The receiver furthermore utilizes software define radio for signal processing and other data manipulation. Here, we describe the receiver implementations in great details, supplementing the crucial parts with laboratory validation results. Finally, we show 2 example datasets, showing usual data obtained during heavy showers and on a quiet day, respectively.
Modeling strategies enhanced by metacognitive tools in high school physics to support student conceptual trajectories and understanding of electricity
Authors: Wade‐Jaimes Katherine , Demir Kadir , Qureshi Azhar
Published: May 2018

Modeling is considered an important scientific practice, and modeling instruction has the potential to support conceptual change in students in physics. However, when students are not taught how to think about modeling, and how to develop and use models, the learning potential of modeling may be limited. This paper argues that the use and explicit teaching of metacognitive tools like interactive questioning and individual reflection increase students’ ability to use and make sense of models. We present a sequence of activities incorporating metacognitive tools with a variety of models (mental, physical, simulated, and mathematical) in a high school physics unit of electricity. Using data from classroom observations, individual student reflections, group‐created posters, and classroom discussion, we found evidence to demonstrate the complicated nature of conceptual change, the importance of using a variety of different representations (models) of a phenomenon, and the critical role of the teacher in learning. Teachers need to be aware of this process and able to give students the time they need to fully explore and develop multiple models and support to think critically about models. Although many classrooms are limited in time, this process is necessary to move beyond rote memorization toward meaningful conceptual change.