Interesting Class Research Articles

On Reverse Elastic Channels and the Asymmetry of Commitment Capacity Under Channel Elasticity

Commitment is an important cryptographic primitive. It is well known that noisy channels are a promising resource to realize commitment in an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">information-theoretically</i> secure manner. However, oftentimes, channel behaviour may be poorly characterized thereby limiting the commitment throughput and/or degrading the security guarantees; a particularly problematic situation arises when a dishonest party, unbeknown to the honest one, maliciously alters the channel characteristics. Reverse elastic channels (RECs) are an interesting class of such <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">unreliable</i> channels where only a dishonest <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">committer</i> , say Alice, can maliciously alter the channel. RECs have attracted recent interest in the study of several cryptographic primitives. Our principal contribution is the REC commitment capacity characterization; this proves a recent related conjecture. A key result is our tight converse which analyses a specific cheating strategy by Alice. Along with elastic channels (ECs), where only a dishonest <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">receiver</i> Bob can alter the channel, RECs are also closely related to the classic unfair noisy channels (UNCs). In stark contrast to UNCs, both RECs and ECs always exhibit positive commitment throughput for all non-trivial channel parameters. Interestingly, our results show that channels with exclusive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">one-sided elasticity</i> for dishonest parties, exhibit a fundamental <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">asymmetry</i> where, a committer with one-sided elasticity has a significantly more debilitating effect on the commitment throughput than a similarly capable receiver.

The third AI summer: AAAI Robert S. Engelmore Memorial Lecture

The third AI summer: AAAI Robert S. Engelmore Memorial Lecture

Magnetic characterization of self-assembled nanostructures in cobalt ferrites using first-order reversal curve (FORC) analysis

Magnetic ceramics are important for numerous technologically relevant applications with a detailed understanding of structure, property, and processing inter-relationships playing a critical role in tailoring magnetic properties. Spinel ferrites are a particularly interesting class of magnetic ceramics of chemical formula AB2O4, with applications including biomedical hyperthermia and high frequency electrical power conversion. In this contribution, we seek to investigate a unique class of Co-ferrites in which spinodal decomposition can produce a ferrite nanocomposite with chemistry and stress state fluctuating within the interior of crystalline grains on the nm-scale, resulting in corresponding fluctuations of intrinsic magnetic properties as well as exchange and magnetostatic interactions. Structural and magnetic characterization of spinel ferrite samples are carried out (1) in the as-milled state prior to thermal processing, (2) after chemical and structural homogenization with a thermal calcination step, and (3) in the spinodal decomposed state following a subsequent annealing treatment within the Co-ferrite miscibility gap. Of note is the formation of a wasp-waisted hysteresis loop which emerges for the spinodal decomposed Co-ferrite sample, indicative of more complex magnetization reversal processes at relatively large applied fields than for homogeneous Co-ferrite samples of similar particle size and identical nominal chemistry. First order reversal curve (FORC) analysis is applied to further characterize the magnetization response, and a conventional interpretation of observed features in the FORC contrast is presented to discuss potential dominant magnetization mechanisms. The work described here represents the first application of FORC to spinodal decomposed magnetic ceramics and provides a strong foundation for future investigations seeking to quantitatively describe the impacts of nm-scale chemical, structural, and magnetic fluctuations on magnetization processes in ferrite spinel nanocomposite systems.

Superconductivity in (Ba,K)SbO3

(Ba,K)BiO3 constitute an interesting class of superconductors, where the remarkably high superconducting transition temperature Tc of 30 K arises in proximity to charge density wave order. However, the precise mechanism behind these phases remains unclear. Here, enabled by high-pressure synthesis, we report superconductivity in (Ba,K)SbO3 with a positive oxygen–metal charge transfer energy in contrast to (Ba,K)BiO3. The parent compound BaSbO3−δ shows a larger charge density wave gap compared to BaBiO3. As the charge density wave order is suppressed via potassium substitution up to 65%, superconductivity emerges, rising up to Tc = 15 K. This value is lower than the maximum Tc of (Ba,K)BiO3, but higher by more than a factor of two at comparable potassium concentrations. The discovery of an enhanced charge density wave gap and superconductivity in (Ba,K)SbO3 indicates that strong oxygen–metal covalency may be more essential than the sign of the charge transfer energy in the main-group perovskite superconductors.

Improving stability of iron oxide nanofluids for enhanced oil recovery: Exploiting wettability modifications in carbonaceous rocks

Superparamagnetic Iron Oxide Nanoparticles (SPION) exhibit relatively low toxicity and cost, while their chemical versatility provides an interesting class of materials for the development of nanofluids for advanced oil recovery. In this article, we present a comprehensive characterization of SPION modified with the disodium 4,5-dihydroxy-1,3-benzenedisulfonate (HBS) anionic ligand, forming a coating capable of improving the colloidal stability of the nanofluid, even in brine containing up to 22,000 ppm of sodium chloride. Fourier-transform infrared spectroscopy (FTIR) and x-ray photoelectron spectrometry (XPS) data demonstrated the chemical modification of the surface of the particles by the HBS ligand, through the linking of the catechol group, expose the sulfonate groups on the surface of the SPION-HBS. The anionic groups modify the surface charge distribution of the nanoparticles, shifting the isoelectric point of the nanoparticles from pH 6.3 (SPION) to less than pH 2 (SPION-HBS). This fact affords greater stability, supporting the drastic conditions of enhanced oil recovery (EOR) application. The interfacial properties of these particles were also investigated, revealing a slight reduction in the interfacial tension (IFT) of the nanofluid/oil, and small changes in the contact angle (CA) measured as a decane droplet on a glass surface. Despite the slight reduction in IFT and CA, spontaneous imbibition experiments showed a dramatic improvement in oil production in the nanofluid group, reaching a relative value of 2.75 times greater than in the control, at the end of the 5-month trial. The higher oil production achieved with the SPION-HBS nanofluid can be attributed to a more efficient change in wettability, reflecting the role of electrostatic interactions between the sulfonate groups at the particle surface and the porous surface of limestone rock. Since there was no surfactant in the composition of the nanofluid, the observed effects can only be attributed to the influence of the nanoparticles in the EOR process.

Pharmacology and toxicology of tannins.

Tannins are an interesting class of polyphenols, characterized, in almost all cases, by a different degree of polymerization, which, inevitably, markedly influences their bioavailability, as well as biochemical and pharmacological activities. They have been used for the process of tanning to transform hides into leather, from which their name derives. For several time, they have not been accurately evaluated, but now researchers have started to unravel their potential, highlighting anti-inflammatory, antimicrobial, antioxidant and anticancer activities, as well as their involvement in cardiovascular, neuroprotective and in general metabolic diseases prevention. The mechanisms underlying their activity are often complex, but the main targets of their action (such as key enzymes modulation, activation of metabolic pathways and changes in the metabolic fluxes) are highlighted in this review, without losing sight of their toxicity. This aspect still needs further and better-designed study to be thoroughly understood and allow a more conscious use of tannins for human health.

The Effectiveness of the Real-case Online-based Learning on Nursing Care Plan Self-efficacy

BACKGROUND: Online learning has become a new thing that is adapted and supports the learning process, including in nursing education during the COVID-19 pandemic. However, various studies report that there are limitations to conduct the online learning. AIM: The objective of the study was to identify the effectiveness of the real-case online-based learning in understanding the nursing care plan process and, self-efficacy from the students’ perspective. METHODS: Mix methods; explanatory sequential designs. One-hundred and fifty-seven respondents participated in the quantitative approach (64 students in the intervention group and, 93 students in the control group). Six students among the quantitative approach were participated in the qualitative approach. Mann-Whitney’s statistical approach was used for the quantitative approach, while Colaizzi’s method of data analysis was used for the qualitative approach. RESULTS: There was no significant difference between the control and treatment groups in the nursing care plan (p = 0.13) and student self-efficacy (p = 0.45). In addition, there were five themes identified by the students’ perspectives regarding the real case online learning, including; 1) opinions on learning, 2) the feelings experienced during the learning, 3) learning benefits, 4) learning barriers, and 5) expectations of learning. CONCLUSION: The real case online learning provides a different atmosphere including more interesting class, interactive interaction with the patients directly and providing positive experience for the students in the form of seeing the real cases online. The infrastructure/facilities (internet availability and stability) are important factors in the online learning process. The real case online learning is recommended as an alternative of learning that is more interesting and interactive involving the patients, students, and direct supervisors. Further research on the learning process of nursing care with a mixed system; limited offline and online cases with real, comprehensive, and interdisciplinary approaches are recommended.

Branching quantum convolutional neural networks

Neural-network-based algorithms have garnered considerable attention for their ability to learn complex patterns from very-high-dimensional data sets towards classifying complex long-range patterns of entanglement and correlations in many-body quantum systems, and towards processing high-dimensional classical data sets. Small-scale quantum computers are already showing potential gains in learning tasks on large quantum and very large classical data sets. A particularly interesting class of algorithms, the quantum convolutional neural networks (QCNNs) could learn features of a quantum data set by performing a binary classification task on a nontrivial phase of quantum matter. Inspired by this promise, we present a generalization of QCNN, the ``branching quantum convolutional neural network,'' or bQCNN, with substantially higher expressibility. A key feature of bQCNN is that it leverages midcircuit (intermediate) measurement results, realizable on several current quantum devices, obtained in pooling layers to determine which sets of parameters will be used in the subsequent convolutional layers of the circuit. This results in a ``branching'' structure, which allows for a greater number of trainable variational parameters in a given circuit depth. This is of particular use in current-day noisy intermediate-scale quantum devices, where circuit depth is limited by gate noise. We present an overview of the Ansatz structure and scaling and provide evidence of its enhanced expressibility compared with QCNN. Using artificially constructed large data sets of training states as a proof of concept, we demonstrate the existence of training tasks in which bQCNN far outperforms an ordinary QCNN. We provide an explicit example of such a task in the recognition of the transition from a symmetry protected topological to a trivial phase induced by multiple, distinct perturbations. Finally, we present future directions where the classical branching structure and increased density of trainable parameters in bQCNN would be particularly valuable.

Novel tetrameric cell penetrating antimicrobial peptoids effective against mycobacteria and drug-resistant Staphylococcus aureus.

Antimicrobial peptides (AMPs) are short, cationic, amphipathic molecules that have gained tremendous popularity as alternatives to traditional antibiotics due to their lower propensity to develop bacterial resistance. However, the clinical developability of AMPs remains impeded due to shortcomings such as proteolytic instability and poor penetration leading to low bioavailability. To improve the access of AMPs to cells and subsequent bacteria killing, we evaluated the cell-penetrating and antimicrobial properties of three novel libraries of synthetic peptoids using Minimum Inhibitory Concentration, killing efficacy and membrane permeabilization assays against mycobacteria and Staphylococcus aureus. In addition, we investigated cell selectivity using mammalian cells to assess peptoid toxicity. We showed that short tetrameric Rhodamine B-labeled peptoids composed of a balance of aromatic and lipophilic residues have potent selective antimicrobial activity against a range of microorganisms. The most potent candidates were active against drug-resistant S. aureus isolates as well as mycobacterial strains, with cell penetrating capabilities reported in HeLa and RAW 264.7 macrophage cells. These data suggest that peptoids with novel dual functionalities may potentially be an interesting class of therapeutics and/or molecular delivery agents for anti-infective purposes.

Recent Advances in the Biological Activity of s-Triazine Core Compounds.

An effective strategy for successful chemotherapy relies on creating compounds with high selectivity against cancer cells compared to normal cells and relatively low cytotoxicity. One such approach is the discovery of critical points in cancer cells, i.e., where specific enzymes that are potential therapeutic targets are generated. Triazine is a six-membered heterocyclic ring compound with three nitrogen replacing carbon-hydrogen units in the benzene ring structure. The subject of this review is the symmetrical 1,3,5-triazine, known as s-triazine. 1,3,5-triazine is one of the oldest heterocyclic compounds available. Because of its low cost and high availability, it has attracted researcher attention for novel synthesis. s-Triazine has a weak base, it has much weaker resonance energy than benzene, therefore, nucleophilic substitution is preferred to electrophilic substitution. Heterocyclic bearing a symmetrical s-triazine core represents an interesting class of compounds possessing a wide spectrum of biological properties such as anti-cancer, antiviral, fungicidal, insecticidal, bactericidal, herbicidal and antimicrobial, antimalarial agents. They also have applications as dyes, lubricants, and analytical reagents. Hence, the group of 1,3,5-triazine derivatives has developed over the years. Triazine is not only the core amongst them, but is also a factor increasing the kinetic potential of the entire derivatives. Modifying the structure and introducing new substituents makes it possible to obtain compounds with broad inhibitory activity on processes such as proliferation. In some cases, s-triazine derivatives induce cell apoptosis. In this review we will present currently investigated 1,3,5-triazine derivatives with anti-cancer activities, with particular emphasis on their inhibition of enzymes involved in the process of tumorigenesis.

Structural and Functional Diversity of Animal Toxins Interacting With GPCRs.

Peptide toxins from venoms have undergone a long evolutionary process allowing host defense or prey capture and making them highly selective and potent for their target. This has resulted in the emergence of a large panel of toxins from a wide diversity of species, with varied structures and multiple associated biological functions. In this way, animal toxins constitute an inexhaustible reservoir of druggable molecules due to their interesting pharmacological properties. One of the most interesting classes of therapeutic targets is the G-protein coupled receptors (GPCRs). GPCRs represent the largest family of membrane receptors in mammals with approximately 800 different members. They are involved in almost all biological functions and are the target of almost 30% of drugs currently on the market. Given the interest of GPCRs in the therapeutic field, the study of toxins that can interact with and modulate their activity with the purpose of drug development is of particular importance. The present review focuses on toxins targeting GPCRs, including peptide-interacting receptors or aminergic receptors, with a particular focus on structural aspects and, when relevant, on potential medical applications. The toxins described here exhibit a great diversity in size, from 10 to 80 amino acids long, in disulfide bridges, from none to five, and belong to a large panel of structural scaffolds. Particular toxin structures developed here include inhibitory cystine knot (ICK), three-finger fold, and Kunitz-type toxins. We summarize current knowledge on the structural and functional diversity of toxins interacting with GPCRs, concerning first the agonist-mimicking toxins that act as endogenous agonists targeting the corresponding receptor, and second the toxins that differ structurally from natural agonists and which display agonist, antagonist, or allosteric properties.

Association between Enjoyment in Physical Education Online Classes and Physical Activity Levels in Adolescents during the COVID-19 Pandemic

Motivation, with special emphasis on intrinsic motivation is important factor that influences physical activity levels (PAL). The COVID-19 pandemic forced Physical education (PE) teachers to switch to online classes, which increased the problem of keeping students motivated to be physically active. This study aimed to determine the associations between enjoyment in online PE classes and PAL during the COVID-19 lockdown. 198 highschool students aged 14-19 years participated in this study. Variables included interest and enjoyment in PE classes assessed by the Intrinsic Motivation Inventory questionnaire and PAL assessed by Physical Activity Questionnaire for Adolescents. Pearson’s correlation coefficient was calculated to evaluate the associations between variables. Independent samples T-test and χ2 test were used for determining the gender differences in study variables. Significant correlation between PAL and interest/enjoyment in online PE classes was recorded (R=0.23, p&lt;0.05). There were no significant differences between girls and boys in the total subset interest/ enjoyment of intrinsic motivation. However, the difference was observed in the subset enjoyment (χ2(1, N=198)=9.53), with boys showing more enjoyment. Because of the evidenced positive association between interest/enjoyment in PE classes and PAL, it is crucial to provide students fun and interesting PE online classes to maintain PAL during the pandemic and similar situations. The special emphasis should be placed on girls.

Versatile Approach for the Synthesis of Furo-coumarin Derivatives

Abstract: Owing to useful physio-chemical properties of furo-coumarin derivatives, their synthetic and mechanistic investigation has been reported here. We have demonstrated a range of synthetic approaches to access furan-fused coumarin derivatives. Many metalmediated, base, and acid-catalyzed approaches have been revealed for the formation of this coumarin-based fused heterocycles of biological importance. In addition to this, microwaveassisted synthetic routes have also been revealed. The last and most useful approach for the synthesis of these heterocycles includes the use of purely solvent as a reaction media for synthesizing these interesting classes of heterocycles.

Prime ideals and Noetherian properties in vector lattices

In this paper we study the set of prime ideals in vector lattices and how the properties of the prime ideals structure the vector lattice in question. The different properties that will be considered are firstly, that all or none of the prime ideals are order dense, secondly, that there are only finitely many prime ideals, thirdly, that every prime ideal is principal, and lastly, that every ascending chain of prime ideals is stationary (a property that we refer to as prime Noetherian). We also completely characterize the prime ideals in vector lattices of piecewise polynomials, which turns out to be an interesting class of vector lattices for studying principal prime ideals and ascending chains of prime ideals.

NHC‐Catalyzed 1,4‐Elimination in the Dearomative Activation of 3‐Furaldehydes towards (4+2)‐Cycloadditions

AbstractA dearomative formal (4+2)‐cycloaddition reaction between 2‐substituted 3‐furaldehydes derivatives and isatins or α,α,α‐trifluoroacetophenones as electrophiles has been established under NHC‐catalysis. This approach utilizes the process of hydrogen chloride 1,4‐elimination leading to a highly reactive NHC‐bound heterocyclic o‐QDM intermediates derived from 3‐furaldehydes, which play a key role in the process. By using this strategy, a series of structurally diverse 6,7‐dihydro‐4H‐furo[3,2‐c]pyran‐4‐ones was prepared in 41–85% yields. In addition, the potential of the obtained (4+2)‐cycloadducts has been confirmed in the synthesis of interesting class of spirooxindole derivative containing 6,7‐dihydro‐4H‐furo[3,2‐c]pyran scaffold.magnified image

Spatial search on Johnson graphs by continuous-time quantum walk

Spatial search on graphs is one of the most important algorithmic applications of quantum walks. To show that a quantum-walk-based search is more efficient than a random-walk-based search is a difficult problem, which has been addressed in several ways. Usually, graph symmetries aid in the calculation of the algorithm's computational complexity, and Johnson graphs are an interesting class regarding symmetries because they are regular, Hamilton-connected, vertex- and distance-transitive. In this work, we show that spatial search on Johnson graphs by continuous-time quantum walk achieves the Grover lower bound $\pi\sqrt{N}/2$ with success probability $1$ asymptotically for every fixed diameter, where $N$ is the number of vertices. The proof is mathematically rigorous and can be used for other graph classes.

Production and Structural Diversification of Withanolides by Aeroponic Cultivation of Plants of Solanaceae: Cytotoxic and Other Withanolides from Aeroponically Grown Physalis coztomatl.

Withanolides constitute one of the most interesting classes of natural products due to their diversity of structures and biological activities. Our recent studies on withanolides obtained from plants of Solanaceae including Withania somnifera and a number of Physalis species grown under environmentally controlled aeroponic conditions suggested that this technique is a convenient, reproducible, and superior method for their production and structural diversification. Investigation of aeroponically grown Physalis coztomatl afforded 29 withanolides compared to a total of 13 obtained previously from the wild-crafted plant and included 12 new withanolides, physacoztolides I−M (9–13), 15α-acetoxy-28-hydroxyphysachenolide C (14), 28-oxophysachenolide C (15), and 28-hydroxyphysachenolide C (16), 5α-chloro-6β-hydroxy-5,6-dihydrophysachenolide D (17), 15α-acetoxy-5α-chloro-6β-hydroxy-5,6-dihydrophysachenolide D (18), 28-hydroxy-5α-chloro-6β-hydroxy-5,6-dihydrophysachenolide D (19), physachenolide A-5-methyl ether (20), and 17 known withanolides 3–5, 8, and 21–33. The structures of 9–20 were elucidated by the analysis of their spectroscopic data and the known withanolides 3–5, 8, and 21–33 were identified by comparison of their spectroscopic data with those reported. Evaluation against a panel of prostate cancer (LNCaP, VCaP, DU-145, and PC-3) and renal carcinoma (ACHN) cell lines, and normal human foreskin fibroblast (WI-38) cells revealed that 8, 13, 15, and 17–19 had potent and selective activity for prostate cancer cell lines. Facile conversion of the 5,6-chlorohydrin 17 to its 5,6-epoxide 8 in cell culture medium used for the bioassay suggested that the cytotoxic activities observed for 17–19 may be due to in situ formation of their corresponding 5β,6β-epoxides, 8, 27, and 28.

Monodromy conjecture for log generic polynomials

A log generic hypersurface in $$\mathbb {P}^n$$ with respect to a birational modification of $$\mathbb {P}^n$$ is by definition the image of a generic element of a high power of an ample linear series on the modification. A log very-generic hypersurface is defined similarly but restricting to line bundles satisfying a non-resonance condition. Fixing a log resolution of a product $$f=f_1\ldots f_p$$ of polynomials, we show that the monodromy conjecture, relating the motivic zeta function with the complex monodromy, holds for the tuple $$(f_1,\ldots ,f_p,g)$$ and for the product fg, if g is log generic. We also show that the stronger version of the monodromy conjecture, relating the motivic zeta function with the Bernstein–Sato ideal, holds for the tuple $$(f_1,\ldots ,f_p,g)$$ and for the product fg, if g is log very-generic. Even the case $$f=1$$ is intricate, the proof depending on nontrivial properties of Bernstein–Sato ideals, and it singles out the class of log (very-) generic hypersurfaces as an interesting class of singularities on its own.

Thermal analysis of MgFe-Cl Layered doubled hydroxide (LDH) directly synthetized and produced \u201cvia memory effect\u201d

Layered doubled hydroxides (LDHs) are known to be an interesting class of 2D layered materials, with a wide range of possible composition and a flexible structure suitable for topochemical reactions. Thus, LDHs have been applying in different fields, such as catalysis, energy storage and all the applications in which a high exchange capability (of both cations and anions) is required. For remediation purpose, a MgFe-Cl LDH {[({mathrm{Mg}}_{0.66}^{2+}{mathrm{Fe}}_{0.33}^{3+}{left(mathrm{OH}right)}_{2}]}^{0.33+}{({mathrm{Cl}}_{0.33}^{-})}^{0.33-} (MFC in the following) could be a promising candidate to capture the toxic CrO42− from water, in exchange with the Cl− in an efficient way. The synthesis of this compound might seem simple, consisting of a coprecipitation reaction, and actually, it is strongly affected by the environmental carbon dioxide able to replace the Cl− with the more stable CO32−. To avoid this problem, LDHs could be also prepared with a rehydration of their calcinated oxide (memory effect). In this work were prepared two samples of MFC: one via coprecipitation (MFC-1 in the following) and one via “memory effect” (MFC-mem in the following). Both the compounds were characterized by means of X-ray powder diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR) and differential thermal analysis-thermogravimetry (DTA-TG) coupled with evolved gas analysis. The results demonstrated that the synthesis of pure MFC is very difficult, and only a minimum contamination of carbon dioxide led to the formation of the carbonate LDH in a massive way. It was also demonstrated that Mg-Fe LDHs in the presence of carbonate could catalyse the formation of the formic acid (HCOOH) at low temperature (< 300 °C).

Symbolic power containments in singular rings in positive characteristic

The containment problem for symbolic and ordinary powers of ideals asks for what values of a and b we have $$I^{(a)} \subseteq I^b$$ . Over a regular ring, a result by Ein–Lazarsfeld–Smith, Hochster–Huneke, and Ma–Schwede partially answers this question, but the containments it provides are not always best possible. In particular, a tighter containment conjectured by Harbourne has been shown to hold for interesting classes of ideals—although it does not hold in general. In this paper, we develop a Fedder (respectively, Glassbrenner) type criterion for F-purity (respectively, strong F-regularity) for ideals of finite projective dimension over F-finite Gorenstein rings and use our criteria to extend the prime characteristic results of Grifo–Huneke to singular ambient rings. For ideals of infinite projective dimension, we prove that a variation of the containment still holds, in the spirit of work by Hochster–Huneke and Takagi.