The Cover Feature shows some nickel(II) complexes of a class of quinquedentate ligands that consist of a tetra‐aza macrocycle (e.g. cyclam) and of a coordinating side chain. These ligands, which hold ...the metal ion firmly in the ring and can sting it on command from above with an aggressive tail, have been named scorpiands and their metal complexes scorpiates. The movement of the side chain, whether coordinated or uncoordinated, can be controlled through acid‐base or redox processes and may induce dramatic changes of the properties of the complex (color, spin multiplicity, oxidation state, light emission). More information can be found in the Review by L. Fabbrizzi.
In this study, twenty-two water samples were collected from boreholes (BH), and streams to evaluate drinking water quality, its distribution, identification of contamination sources and apportionment ...for Moti village, northern Pakistan. An atomic absorption spectrophotometer (AAS) is utilized to determine the level of heavy metals in water such as arsenic (As), zinc (Zn), lead (Pb), copper (Cu), cadmium (Cd), manganese (Mn), and ferrous (Fe). Groundwater chemistry and its quantitative driving factors were further explored using multivariate statistical methods, Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF) models. Finally, a total of eight electrical resistivity tomographs (ERTs) were acquired across i) the highly contaminated streams; ii) the villages far away from contaminated streams; and iii) across the freshwater stream. In the Moti village, the mean levels (mg/l) of heavy metals in water samples were 7.2465 (As), 0.4971 (Zn), 0.5056 (Pb), 0.0422 (Cu), 0.0279 (Cd), 0.1579 (Mn), and 0.9253 (Fe) that exceeded the permissible limit for drinking water (such as 0.010 for As and Pb, 3.0 for Zn, 0.003 for Cd and 0.3 for Fe) established by the World Health Organization (WHO, 2008). The average entropy weighted water quality index (EWQI) of 200, heavy metal pollution index (HPI) of 175, heavy metal evaluation index (HEI) of 1.6 values reveal inferior water quality in the study area. Human health risk assessment, consisting of hazard quotient (HQ) and hazard index (HI), exceeded the risk threshold (>1),indicating prevention of groundwater usage. Results obtained from the PCA and PMF models indicated anthropogenic sources (i.e. industrial and solid waste) responsible for the high concentration of heavy metals in the surface and groundwater. The ERTs imaged the subsurface down to about 40 m depths and show the least resistivity values (<11 Ωm) for subsurface layers that are highly contaminated. However, the ERTs revealed relatively high resistivity values for subsurface layers containing fresh or less contaminated water. Filtering and continuous monitoring of the quality of drinking water in the village are highly recommended.
•Heavy metals ions from municipality and industry affected groundwater chemistry.•Hydrochemical Indices (EWQI, HPI, HEI) was used to determine the water quality.•Hazard quotient (HQ) and hazard index (HI) was used for the evaluation of trace elements in terms of public health risk.•PCA and PMF methods were used for source identification and apportionment.•ERT images reveals that Shayya stream has relative good water quality.
This review tells the story of scorpiands, polyamine ligands which, when specifically stimulated, act as scorpions, and of their metal complexes, scorpiates. Scorpiands consist of a tetramine ...macrocycle (typically cyclam) capable of firmly including a transition metal and of a side chain ending with a nitrogen containing coordinating group: under unperturbed conditions the coordinating group is bound to the metal (ON), but on addition of acid the nitrogen is protonated and comes off the metal (OFF). Alternating acid/base addition makes the side chain move imitating the tail of a scorpion that bites a prey firmly immobilized by the claws. Occurrence of the ON‐OFF motion is monitored by the colour change of the scorpiate complexes associated to the change of coordination or by fluorescence quenching/restoring when a light‐emitting substituent is linked to the side arm. Scorpiate complexes can be considered optical molecular switches and, from a different standpoint, molecular machines able to convert chemical energy into mechanical work.
Artificial scorpions displaying beneficial activities: Quinquedentate ligands made of a cyclam ring and of a side chain ending with a coordinating group may sting from the top the encircled metal, behaving as scorpions. The side chain can be activated by either a chemical or electrochemical input and its motion is signalled by a colour change or by quenching/restoring of fluorescence.
This note is a comment on a recent paper in this journal by Moti Mizrahi. Mizrahi claims that the factivity of knowledge entails that knowledge requires epistemic certainty. But the argument that ...Mizrahi presents does not proceed from factivity to certainty. Instead, it proceeds from a premise about the relationship between grounds and knowledge to the conclusion about certainty.
This reply provides further grounds to doubt Mizrahi’s argument for an infallibilist theory of knowledge. It is pointed out that the fact that knowledge requires both truth and justification does not ...entail that the level of justification required for knowledge be sufficient to guarantee truth. In addition, an argument presented by Mizrahi appears to equivocate with respect to the interpretation of the phrase “p cannot be false”.
Two-dimensional (2D) semiconductor-based devices are mostly using in-plane direction current in their device architecture, to justify the novelty of 2D-like ultrathin electron devices beyond ...conventional 3D devices. Those ultrathin 2D devices, however, would unavoidably meet high contact resistance issue. In the present study, thick 2D-layered crystals are rather chosen for a meaningful vertical device, which alleviates the contact resistance issue using a large contact area. Here, we have fabricated Pt/120 nm-thick MoSe2 Schottky diodes with different Ohmic metal contacts of Au, Ti/Au, and MoTi/Au. These diodes are then monolithically integrated with a capacitor of ~20 nm-thick h-BN or 50 nm-thick ALD Al2O3. This way, van der Waals crystal radios are successfully fabricated for wireless RF energy harvesting. In terms of crystal radio device performance, the best results come from Pt/n-MoSe2 Schottky diode with MoTi contact and h-BN capacitor combination. This superiority is attributed to the excellent Ohmic behavior of MoTi alloy contact. At last, when AM demodulation experiments are conducted with 1 MHz carrier frequency/audio frequency-mixed signals, the crystal radio with MoTi demonstrates the highest output DC voltage envelope, allowing loud audio sound.
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•Wireless RF energy harvest using a vertical Schottky diode.•Realization of a vdW crystal radio utilizing two types of 2D crystals.•MoTi alloy contact implemented on 2D-layered crystal, MoSe2.•Excellent Ohmic behavior of MoTi contact.
This research explores the influencing factors of learning satisfaction in blended learning. Three dimensions are proposed: perceived usefulness, perceived ease of use, and learning motivation. It ...studied how these variables affect students’ learning satisfaction. The research hypotheses are: (1) Perceived ease of use positively affects perceived usefulness; (2) Perceived usefulness and perceived ease of use will have a positive effect on learning motivation; (3) Learning motivation positively affects learning satisfaction; (4) Perceived usefulness has a positive intermediary effect on the relationship between perceived ease of use and learning motivation. Participants included 173 freshmen who took the first-year interactive game design course at Ling Tung University in Taichung, Taiwan. The questionnaire survey method is applied in this research to analyze the relationship between the variables and verify the hypothesis based on the collected 173 valid questionnaires. The partial least square method structural equation model (PLS-SEM) is used to carry out structural equation modeling to study the relationship between latent variables. It explains that the perceived ease of use affects the perceived usefulness. Perceived usefulness and perceived ease of use have a positive impact on learning motivation. Learning motivation has a positive impact on learning satisfaction. Perceived usefulness as an intermediary factor of perceived ease of use has an indirect impact on learning motivation. The contribution of this research is to provide empirical evidence and explain what factors may affect learning satisfaction. Some other related factors that may affect learning satisfaction should be taken as the factors that teachers should pay attention to when implementing blended learning.
The Monastery of Saint Stepanos, in Julfa, is located in northwesternIran, in the province of East Azerbaijan. Whilst the exactdate of construction is unknown, the building displays ...exceptionalarchitecture. It is believed that the monastery was built between thetenth and seventeenth centuries, and this doubt emphasises the needto investigate the nature of structure and decoration. The Monasteryis situated in a deep canyon beside the Araxes river, on the Iranianside of the border between Iran and the Nakhichevan AutonomousRepublic in Azerbaijan. It was originally built in the ninth century,and was rebuilt during the Safavid era after being damaged by warsand earthquakes. Considering that scholars and travel writers, such asthe French Traveller Taurine, consider the construction of this buildingto be from the Safavid period, probing the structural and decorativesimilarities of this building with Safavid period architecture can bea way of dating this outstanding historical monument. During theSafavid period, the Portuguese arrival on the island of Hormuz inthe Persian Gulf (1515–1622 AD) prepared the ground for the arrivaland activity of European Christians, who spread Christianity and itsculture. One of the earliest consequences of this was the constructionof the Monastery and other Christian architecture. The basic objectivesof the article are to study the influence of Portuguese Christianarchitecture on the construction of Saint Stepanos Monastery, and toinvestigate the influence of Safavid structural design on its architecture.The main questions, are what influence has the architecture of SaintStepanos Monastery had on Christian architecture in Portugal,and what influence did the architecture the Monastery have on thearchitecture of the Safavid period?This research for this article is descriptive and analytical based onhistorical information, available documents and existing images. Anexamination of the architectural similarities between Saint Stepanos
Monastery in Julfa and Christian architecture in Portugal is essentialfor a more accurate understanding of the Monastery.
Citizen science approaches to data collection are growing in popularity, in part because of their potential for achieving both scientific and educational objectives. Evaluating the impacts of ...participation on citizen scientists is important, yet such evaluations are still relatively rare. In addition, recent literature reviews indicate that existing studies often focus on content learning, make limited use of existing scales, and rarely report null results. This paper reports an evaluation of the demographic profile, motivations and learning outcomes of participants in the Dutch National Bee Survey, a national-scale citizen science project involving citizens in collecting observational data of wild bees. Using a repeated measures survey study, we assessed the impact of participation on respondents’ attitudes and behavioural intentions regarding bees, and their attitudes towards nature, citizenship, and citizen science. Our baseline (N = 373) and follow-up (N = 208) surveys indicate that our respondents are of a relatively high age and education level, have a pre-existing affinity with nature, and are strongly motivated by conservation concerns and learning about bees. Assessment of learning outcomes indicated a significant difference between two types of self-report questions: respondents reported significant gains in knowledge and appreciation of wild bees, yet attitudinal scales indicated no significant shifts in attitudes towards bees, nature, citizen science, or citizenship. In our discussion, we suggest several explanations for this finding, including respondents’ pre-existing affinity with nature, and advance suggestions for future research into citizen science learning outcomes.
This is open access book provides plenty of pleasant mathematical surprises. There are many fascinating results that do not appear in textbooks although they are accessible with a good knowledge of ...secondary-school mathematics. This book presents a selection of these topics including the mathematical formalization of origami, construction with straightedge and compass (and other instruments), the five- and six-color theorems, a taste of Ramsey theory and little-known theorems proved by induction. Among the most surprising theorems are the Mohr-Mascheroni theorem that a compass alone can perform all the classical constructions with straightedge and compass, and Steiner's theorem that a straightedge alone is sufficient provided that a single circle is given. The highlight of the book is a detailed presentation of Gauss's purely algebraic proof that a regular heptadecagon (a regular polygon with seventeen sides) can be constructed with straightedge and compass. Although the mathematics used in the book is elementary (Euclidean and analytic geometry, algebra, trigonometry), students in secondary schools and colleges, teachers, and other interested readers will relish the opportunity to confront the challenge of understanding these surprising theorems.
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