Search Results (17)

Background: Prosthetic vascular graft infection (PVGI) is a serious complication associated with vascular prostheses. Nuclear medicine techniques, including [¹⁸F]fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) and ^99mtechnetium-hexamethylpropylene amine oxime (HMPAO)-labeled leukocyte (WBC) scintigraphy, are part of the MAGIC diagnostic criteria for PVGI. Methods: In this retrospective study, we analyzed eight patients with suspected PVGI who underwent both [¹⁸F]FDG PET/CT and WBC scintigraphy within an average of 8 days. Results: Of all eight patients (median age 69 years), three showed concordant positive results with both PET/CT and WBC, and their final diagnosis confirmed the presence of infection; five showed discordant results: in all five of these patients, PET/CT showed false-positive findings, whereas WBC correctly identified five true-negative cases. Conclusions: [¹⁸F]FDG PET/CT is highly sensitive but prone to false positives. WBC scintigraphy, combined with SPECT/CT, particularly in the evaluation of the treatment response, showed greater specificity, and it may warrant consideration as a MAGIC major diagnostic criterion for PVGI. Full article

The current investigation aims to offer fundamental, molecular- to microscopic-level descriptions of methane gas inside natural source clay minerals. Texas montmorillonite (STx-1), Georgia kaolinite (KGa-2), and Ca²⁺-saturated Texas montmorillonite (Ca-STx-1, Ca-bentonite) were utilized as subsurface model clay minerals for elucidating nano-confinement behaviors of ¹³C-labeled methane gas. High-pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) was used to describe the interactions between methane and the clays by varying temperature and pressure. Proton-decoupled ¹³C-NMR spectra were acquired at 28.2 bar at 307 K, 32.6 bar at 346 K, 56.4 bar at 307 K, 65.1 bar at 346 K, 112.7 bar at 307 K, and 130.3 bar at 346 K. In the pure state, no significant thermal effect on the behavior of methane was observed. However, there was a perceptible variation in the chemical shift position of confined methane in the mixtures with the clays up to 346 K. Conversely, the ¹³C-NMR chemical shift of methane altered by varying pressure in a pure state, and the mixtures with clays, attributed to the interaction of methane with the clay surfaces or the nanopore network of the clay–silica mixed phase. Pressure-induced shifts in methane peak positions were observed: 0.25 ppm (28.2–56.4 bar) and 0.47 ppm (56.4–112.3 bar) at 307 K. For methane in a montmorillonite mixture, shifts were 0.32 ppm for bulk-like methane and 0.20 ppm for confined methane under similar conditions. At 346 K, increasing pressure from 65.1 to 130.3 bar caused shifts exceeding 0.50 ppm, with bulk-like methane showing a 0.64 ppm shift and confined methane a 0.57 ppm shift. There was only one ¹³C-NMR methane peak in the mixture with either kaolinite (KGa-2) or Ca-bentonite with line broadening compared to that of pure methane. Still, two peaks were observed in the mixture with STx-1, explained by the imbibition and mobility of methane in the pore network. Full article

Peptides are an important class of biomolecules that perform many physiological functions and which occupy a significant and increasing share of the pharmaceutical market. Methods to determine the solid-state structures of peptides in different environments are important to help understand their biological functions and to aid the development of drug formulations. Here, a new magic-angle spinning (MAS) solid-state nuclear magnetic resonance (SSNMR) approach is described for the structural analysis of uniformly ¹³C-labeled solid peptides. Double-quantum (DQ) coherence between selective pairs of ¹³C nuclei in peptide backbone and side-chain CH₃ groups is excited to provide restraints on (i) ¹³C–¹³C internuclear distances and (ii) the relative orientations of C–H bonds. DQ coherence is selected by adjusting the MAS frequency to the difference in the resonance frequencies of selected nuclear pairs (the rotational resonance condition), which reintroduces the dipolar coupling between the nuclei. Interatomic distances are then measured using a constant time SSNMR experiment to eliminate uncertainties arising from relaxation effects. Further, the relative orientations of C–H bond vectors are determined using a DQ heteronuclear local field SSNMR experiment, employing ¹³C–¹H coupling amplification to increase sensitivity. These methods are applied to determine the molecular conformation of a uniformly ¹³C-labeled peptide, N-formyl-l-methionyl-l-leucyl-l-phenylalanine (fMLF). From just six distance and six angular restraints, two possible molecular conformations are determined, one of which is in excellent agreement with the crystal structure of a closely related peptide. The method is envisaged to a useful addition to the SSNMR repertoire for the solid-state structure determination of peptides in a variety of forms, including amyloid fibrils and pharmaceutical formulations. Full article

Graphical games describe strategic interactions among a specified network of players. The threshold protocol game is a graphical game that models the adoption of a lesser-used product in a population when individuals benefit by using the same product. The threshold protocol game has historically been considered using infinite, simple graphs. In general, however, players might value some relationships more than others or may have different levels of influence in the graph. These traits are described by weights on graph edges or vertices, respectively. Relative comparisons on arbitrarily weighted graphs have been studied for a variety of graphical games. Alternatively, graph labelings are functions that assign values to the edges and vertices of graphs based on a particular set of rules. This work demonstrates that the outcome of the threshold protocol game can be characterized on a magic square-generalization labeled graph. There are a variety of graph labelings that generalize the concept of magic squares. In each, the labels on similar sets of graph elements sum to a constant. The constant sums of magic square-generalization labelings mean that each player experiences a constant level of influence without needing to specify the value of players relative to one another. The game outcome is compared across different types and features of labelings. Full article

As matrix representations of magic labelings of related hypergraphs, magic squares and their various variants have been applied to many domains. Among various subclasses, trimagic squares have been investigated for over a hundred years. The existence problem of trimagic squares with singly even orders and orders 16n has been solved completely. However, very little is known about the existence of trimagic squares with other even orders, except for only three examples and three families. We constructed normal trimagic squares by using product constructions, row–square magic rectangles, and trimagic pairs of orthogonal diagonal Latin squares. We gave a new product construction: for positive integers p, q, and r having the same parity, other than 1, 2, 3, or 6, if normal p × q and r × q row–square magic rectangles exist, then a normal trimagic square with order pqr exists. As its application, we constructed normal trimagic squares of orders 8q³ and 8pqr for all odd integers q not less than 7 and p, r ∈ {7, 11, 13, 17, 19, 23, 29, 31, 37}. Our construction can easily be extended to construct multimagic squares. Full article

Photosynthetic reaction centers (RCs) are membrane proteins converting photonic excitations into electric gradients. The heliobacterial RCs (HbRCs) are assumed to be the precursors of all known RCs, making them a compelling subject for investigating structural and functional relationships. A comprehensive picture of the electronic structure of the HbRCs is still missing. In this work, the combination of selective isotope labelling of ¹³C and ¹⁵N nuclei and the utilization of photo-CIDNP MAS NMR (photochemically induced dynamic nuclear polarization magic-angle spinning nuclear magnetic resonance) allows for highly enhanced signals from the radical-pair-forming cofactors. The remarkable magnetic-field dependence of the solid-state photo-CIDNP effect allows for observation of positive signals of the electron donor cofactor at 4.7 T, which is interpreted in terms of a dominant contribution of the differential relaxation (DR) mechanism. Conversely, at 9.4 T, the emissive signals mainly originate from the electron acceptor, due to the strong activation of the three-spin mixing (TSM) mechanism. Consequently, we have utilized two-dimensional homonuclear photo-CIDNP MAS NMR at both 4.7 T and 9.4 T. These findings from experimental investigations are corroborated by calculations based on density functional theory (DFT). This allows us to present a comprehensive investigation of the electronic structure of the cofactors involved in electron transfer (ET). Full article

Cryptography is a pivotal application of graph theory in ensuring secure communication systems. Modern cryptography is deeply rooted in mathematical theory and computer science practices. It is widely recognized that encryption and decryption processes are primarily outcomes of mathematical research. Given the increasing importance of safeguarding secret information or messages from potential intruders, it is imperative to develop effective technical tools for this purpose. These intruders are often well-versed in the latest technological advancements that could breach security. To address this, our study focuses on the efficacious combinatorial technique of graph networks using efficient domination and total magic labeling. The introduction of a graph network based on total magic labeling can significantly influence the network’s performance. This research introduces a novel combinatorial method for encrypting and decrypting confidential numbers by leveraging an efficient dominant notion and labeled graph. Full article

Solid-state NMR (ss-NMR) is a powerful tool to investigate noncrystallizable, poorly soluble molecular systems, such as membrane proteins, amyloids, and cell walls, in environments that closely resemble their physical sites of action. Rotational-echo double resonance (REDOR) is an ss-NMR methodology, which by reintroducing heteronuclear dipolar coupling under magic angle spinning conditions provides intramolecular and intermolecular distance restraints at the atomic level. In addition, REDOR can be exploited as a selection tool to filter spectra based on dipolar couplings. Used extensively as a spectroscopic ruler between isolated spins in site-specifically labeled systems and more recently as a building block in multidimensional ss-NMR pulse sequences allowing the simultaneous measurement of multiple distances, REDOR yields atomic-scale information on the structure and interaction of proteins. By extending REDOR to the determination of ¹H–X dipolar couplings in recent years, the limit of measurable distances has reached ~15–20 Å, making it an attractive method of choice for the study of complex biomolecular assemblies. Following a methodological introduction including the most recent implementations, examples are discussed to illustrate the versatility of REDOR in the study of biological systems. Full article

The heightened dipolar interactions in solids render solid-state NMR (ssNMR) spectra more difficult to interpret than solution NMR spectra. On the other hand, ssNMR does not suffer from severe molecular weight limitations like solution NMR. In recent years, ssNMR has undergone rapid technological developments that have enabled structure–function studies of increasingly larger biomolecules, including membrane proteins. Current methodology includes stable isotope labeling schemes, non-uniform sampling with spectral reconstruction, faster magic angle spinning, and innovative pulse sequences that capture different types of interactions among spins. However, computational tools for the analysis of complex ssNMR data from membrane proteins and other challenging protein systems have lagged behind those for solution NMR. Before a structure can be determined, thousands of signals from individual types of multidimensional ssNMR spectra of samples, which may have differing isotopic composition, must be recognized, correlated, categorized, and eventually assigned to atoms in the chemical structure. To address these tedious steps, we have developed an automated algorithm for ssNMR spectra called “ssPINE”. The ssPINE software accepts the sequence of the protein plus peak lists from a variety of ssNMR experiments as inputs and offers automated backbone and side-chain assignments. The alpha version of ssPINE, which we describe here, is freely available through a web submission form. Full article

The future is not what it used to be. A new strain of futurism has taken over the stage of global science-fiction: one whose understanding of the future cannot be distinguished from its understanding of the present. Gone are the days when extraterrestrials in shiny, extravagant outfits mastered fascinating technologies that flirted with magic. Characters in Charlie Brooker’s Black Mirror (2015–2020) dress like us, and the dystopian technology they put up with is, for the most part, a technology that has existed for years. Armando Iannucci’s imagining of a space cruise for rich people in Avenue 5 (2020) overlaps with Elon Musk’s actual plans of sending wealthy tourists to the moon, while Albert Robida’s visionary téléphonoscope (1879) amounts to a sad reminder of our everyday Zoom call. Is not the current COVID-19 crisis the blueprint to the ultimate post-apocalyptic script? Spanish filmmaker Juan Antonio Bayona noted in a recent interview that Steve Soderbergh’s Contagion (2011), originally labeled as a sci-fi movie by IMDB, is now a drama according to the same internet portal. Science is not fiction anymore, which means at least two different things: that science has lost the power to convey the kind of awe that may be later turned into fiction, and that fiction seems to be unable to inspire a narrative of scientific or—broadly speaking—human progress. How can we retrieve the emancipatory value of progress in good old futuristic sci-fi when the future coincides with the present? What should cultural production look like to help us imagine an alternative to financial capitalism in the face of the impossibility of utopia? The answer, I will claim, resides in Franco Berardi’s concept of “futurability”. This paper explores the limits of this concept by reading side by side Javier Olivares’ and Pablo Olivares’ The Ministry of Time (2015) and Oriol Paulo’s Mirage (2018). Full article

In this paper, we define D-magic labelings for oriented graphs where D is a distance set. In particular, we label the vertices of the graph with distinct integers $\{1,2,\dots ,|V\left(G\right)\left|\right\}$ in such a way that the sum of all the vertex labels that are a distance in D away from a given vertex is the same across all vertices. We give some results related to the magic constant, construct a few infinite families of D-magic graphs, and examine trees, cycles, and multipartite graphs. This definition grew out of the definition of D-magic (undirected) graphs. This paper explores some of the symmetries we see between the undirected and directed version of D-magic labelings. Full article

A graph G admits an H-covering if every edge of G belongs to a subgraph isomorphic to a given graph H. G is said to be H-magic if there exists a bijection $f:V\left(G\right)\cup E\left(G\right)\to \{1,2,\dots ,|V\left(G\right)|+|E\left(G\right)\left|\right\}$ such that $w_f\left(H^{\prime }\right)={\sum }_{v\in V\left(H^{\prime }\right)}f\left(v\right)+{\sum }_{e\in E\left(H^{\prime }\right)}f\left(e\right)$ is a constant, for every subgraph $H^{\prime }$ isomorphic to H. In particular, G is said to be H-supermagic if $f\left(V\right(G\left)\right)=\{1,2,\dots ,|V\left(G\right)\left|\right\}$. When H is isomorphic to a complete graph $K_2$, an H-(super)magic labeling is an edge-(super)magic labeling. Suppose that G admits an F-covering and H-covering for two given graphs F and H. We define G to be $(F,H)$-sim-(super)magic if there exists a bijection $f^{\prime }$ that is simultaneously F-(super)magic and H-(super)magic. In this paper, we consider $(K_2,H)$-sim-(super)magic where H is isomorphic to three classes of graphs with varied symmetry: a cycle which is symmetric (both vertex-transitive and edge-transitive), a star which is edge-transitive but not vertex-transitive, and a path which is neither vertex-transitive nor edge-transitive. We discover forbidden subgraphs for the existence of $(K_2,H)$-sim-(super)magic graphs and classify classes of $(K_2,H)$-sim-(super)magic graphs. We also derive sufficient conditions for edge-(super)magic graphs to be $(K_2,H)$-sim-(super)magic and utilize such conditions to characterize some $(K_2,H)$-sim-(super)magic graphs. Full article

The Stopped-Flow apparatus (SF) tracks molecular events by mixing the reactants in sub-millisecond regimes. The reaction of intrinsically or extrinsically labeled biomolecules can be monitored by recording the fluorescence, F(t), anisotropy, r(t), polarization, p(t), or FRET, F(t)_FRET, traces at nanomolar concentrations. These kinetic measurements are critical to elucidate reaction mechanisms, structural information, and even thermodynamics. In a single detector SF, or L-configuration, the r(t), p(t), and F(t) traces are acquired by switching the orientation of the emission polarizer to collect the I_VV and I_VH signals however it requires two-shot experiments. In a two-detector SF, or T-configuration, these traces are collected in a single-shot experiment, but it increases the apparatus’ complexity and price. Herein, we present a single-detector dual-channel SF to obtain the F(t) and r(t) traces simultaneously, in which a photo-elastic modulator oscillates by 90° the excitation light plane at a 50 kHz frequency, and the emission signal is processed by a set of electronic filters that split it into the r(t) and F(t) analog signals that are digitized and stored into separated spreadsheets by a custom-tailored instrument control software. We evaluated the association kinetics of binary and ternary biological complexes acquired with our dual-channel SF and the traditional methods; such as a single polarizer at the magic angle to acquire F(t), a set of polarizers to track F(t), and r(t), and by energy transfer quenching, F(t)_FRET. Our dual-channel SF economized labeled material and yielded rate constants in excellent agreement with the traditional methods. Full article

In early twenty-first-century China, online fantasy is one of the most popular literary genres. This article studies a subgenre of Chinese fantasy named xiuzhen 修真 (immortality cultivation), which draws on Daoist alchemy in particular and Chinese religion and culture in general, especially that which was negatively labelled “superstitious” in the twentieth century, to tell exciting adventure stories. Xiuzhen fantasy is indebted to wuxia xiaoshuo 武俠小說 (martial arts novels), the first emergence of Chinese fantasy in the early twentieth century after the translation of the modern Western discourses of science, religion, and superstition. Although martial arts fiction was suppressed by the modernizing nation-state because it contained the unwanted elements of magic and supernaturalism, its reemergence in the late twentieth century paved the way for the rise of its successor, xiuzhen fantasy. As a type of magical arts fiction, xiuzhen reinvents Daoist alchemy and other “superstitious” practices to build a cultivation world which does not escape but engages with the dazzling reality of digital technology, neoliberal governance, and global capitalism. In this fantastic world, the divide of magic and science breaks down; religion, defined not by faith but embodied practice, serves as the organizing center of society, economy, and politics. Moreover, the subject of martial arts fiction that challenged the sovereignty of the nation-state has evolved into the neoliberal homo economicus and its non-/anti-capitalist alternatives. Reading four exemplary xiuzhen novels, Journeys into the Ephemeral (Piaomiao zhilv 飄渺之旅), The Buddha Belongs to the Dao (Foben shidao 佛本是道), Spirit Roaming (Shenyou 神遊), and Immortality Cultivation 40K (Xiuzhen siwannian 修真四萬年), this article argues that xiuzhen fantasy provides a platform on which the postsocialist generation seek to orient themselves in the labyrinth of contemporary capitalism by rethinking the modernist triad of religion, science, and superstition. Full article

In comparison with the estimated number of about 60,000 executed so-called witches (women and men), the number of executed and punished witch-priests seems to be rather irrelevant. This statement, however, overlooks the fact that it was only during medieval and early modern times that the crime of heresy and witchcraft cost the life of friars, monks, and ordained priests at the stake. Clerics were the largest group of men accused of practicing magic, necromancy, and witchcraft. Demonology and the media (in constant dialogue with trials) reveal the omnipresence of the devil’s cleric with his figure possessing the quality of a ‘super-witch’, labelled as patronus sagarum. In Western Europe, the persecution of Catholic priests played at least two significant roles. First, in confessional debates, it proved to Catholics that Satan was assaulting post-Tridentine Catholicism, the only remaining bulwark of Christianity; for Protestants on the other hand, the news about the devil’s clergy proved that Satan ruled popedom. Second, in the Old Reich and from the start of the 17th century, the prosecution of clerics as the devil’s minions fueled the general debates about the legitimacy of witchcraft trials. In sketching these over-lapping discourses, we meet the devil’s clergy in Catholic political demonology, in the media and in confessional debates, including polemics about Jesuits being witches and sorcerers. Friedrich Spee used the narratives about executed Catholic priests as vital argument to end trials and torture. Inter alia, battling the devil’s clergy played a vital role in campaigns of internal Catholic church reform and clerical infighting. Studying the debates about the devil’s clergy thus provides a better understanding of how the dynamics of the Reformation, counter-Reformation, Catholic Reform, and confessionalization had an impact on European witchcraft trials. Full article