Pouchitis is the most common complication among patients with ulcerative colitis who have undergone restorative proctocolectomy with ileal pouch–anal anastomosis. Pouchitis is actually a spectrum of ...diseases that vary in etiology, pathogenesis, phenotype, and clinical course. Although initial acute episodes typically respond to antibiotic therapy, patients can become dependent on antibiotics or develop refractory disease. Many factors contribute to the course of refractory pouchitis, such as the use of nonsteroidal anti-inflammatory drugs, infection with Clostridium difficile , pouch ischemia, or concurrent immune-mediated disorders. Identification of these secondary factors can help direct therapy.
In this paper, a novel swarm optimization approach, namely sparrow search algorithm (SSA), is proposed inspired by the group wisdom, foraging and anti-predation behaviours of sparrows. Experiments on ...19 benchmark functions are conducted to test the performance of the SSA and its performance is compared with other algorithms such as grey wolf optimizer (GWO), gravitational search algorithm (GSA), and particle swarm optimization (PSO). Simulation results show that the proposed SSA is superior over GWO, PSO and GSA in terms of accuracy, convergence speed, stability and robustness. Finally, the effectiveness of the proposed SSA is demonstrated in two practical engineering examples.
Restorative proctocolectomy with ileal pouch-anal anastomosis has become the procedure of choice for the majority of patients with ulcerative colitis who require surgical treatment. Pouchitis, the ...most common long-term complication of the procedure, involves a spectrum of disease processes with heterogeneous risk factors, clinical features, disease courses and prognoses. In addition, clinical symptoms of pouchitis are not specific and often overlap with those of other inflammatory and functional pouch disorders, such as Crohn's disease of the pouch and irritable pouch syndrome. Pouchoscopy and biopsy, along with laboratory and radiographic evaluations, are often required for accurate diagnosis in patients with symptoms indicative of pouchitis. Dysbiosis has been implicated as a triggering factor for pouchitis, and concurrent infection with pathogens, such as Clostridium difficile, might contribute to disease relapse and exacerbation. Antibiotic therapy is the main treatment modality. However, the management of antibiotic-dependent and antibiotic-refractory pouchitis remains challenging. Secondary causes of pouchitis, such as ischaemia, NSAID use, the presence of concurrent primary sclerosing cholangitis and other systemic immune-mediated disorders, should be evaluated and properly managed.
Abstract
Inflammatory bowel disease (IBD) has been traditionally managed by IBD medical doctors or IBDologists and colorectal surgeons. Complications related to IBD and IBD surgery, such as ...stricture, fistula, and abscess, are common. For the past decade, endoscopic therapy has emerged as a valid treatment option for those complications. Endoscopic therapy provides more effective therapy for those structural complications than medical treatment, while being a less invasive approach than surgery. Endoscopic therapy plays a growing role in bridging medical and surgical therapies and is becoming an important component in the multidisciplinary approach to complex IBD. In fact, endoscopic therapy has become the treatment of choice for anastomotic stricture and anastomotic sinus. The role of endoscopic resection of colitis-associated neoplasia is currently being explored. Interventional IBD is intellectually and technically challenging. We are calling for proper teaching and training of our next generation of IBD interventionists.
Gold-catalyzed intermolecular alkyne oxidation by an N-O bond oxidant has proven to be a powerful method in organic synthesis during the past decade, because this approach would enable readily ...available alkynes as precursors in generating α-oxo gold carbenes. Among those, gold-catalyzed oxidative cyclization of dialkynes has received particular attention as this chemistry offers great potential to build structurally complex cyclic molecules. However, these alkyne oxidations have been mostly limited to noble metal catalysts, and, to our knowledge, non-noble metal-catalyzed reactions such as diyne oxidations have not been reported. Herein, we disclose a copper-catalyzed oxidative diyne cyclization, allowing the facile synthesis of a wide range of valuable pyrrolo3,4-cquinolin-1-ones. Interestingly, by employing the same starting materials, the gold-catalyzed cascade cyclization leads to the divergent formation of synthetically useful pyrrolo2,3-bindoles. Furthermore, the proposed mechanistic rationale for these cascade reactions is strongly supported by both control experiments and theoretical calculations.
In this paper, the event-triggered state estimation problem is investigated for a class of discrete-time multidelayed neural networks with stochastic parameters and incomplete measurements. In order ...to cater for more realistic transmission process of the neural signals, we make the first attempt to introduce a set of stochastic variables to characterize the random fluctuations of system parameters. In the addressed neural network model, the delays among the interconnections are allowed to be different, which are more general than those in the existing literature. The incomplete information under consideration includes randomly occurring sensor saturations and quantizations. For the purpose of energy saving, an event-triggered state estimator is constructed and a sufficient condition is given under which the estimation error dynamics is exponentially ultimately bounded in the mean square. It is worth noting that the ultimate boundedness of the error dynamics is explicitly estimated. The characterization of the desired estimator gain is designed in terms of the solution to a certain matrix inequality. Finally, a numerical simulation example is presented to illustrate the effectiveness of the proposed event-triggered state estimation scheme.
In this study, we first present a generalized Lorenz model (LM) with
M
modes, where
M
is an odd number that is greater than three. The generalized LM (GLM) is derived based on a successive extension ...of the nonlinear feedback loop (NFL) with additional high wavenumber modes. By performing a linear stability analysis with
σ
=
1
0
and
b
=
8
/
3
, we illustrate that: (1) within the 3D, 5D, and 7D LMs, the appearance of unstable nontrivial critical points requires a larger Rayleigh parameter in a higher-dimensional LM and (2) within the 9DLM, nontrivial critical points are stable. By comparing the GLM with various numbers of modes, we discuss the aggregated negative feedback enabled by the extended NFL and its role in stabilizing solutions in high-dimensional LMs. Our analysis indicates that the 9DLM is the lowest order generalized LM with stable nontrivial critical points for all Rayleigh parameters greater than one. As shown by calculations of the ensemble Lyapunov exponent, the 9DLM still produces chaotic solutions. Within the 9DLM, a larger critical value for the Rayleigh parameter,
r
c
=
6
7
9
.
8
, is required for the onset of chaos as compared to a
r
c
=
2
4
.
7
4
for the 3DLM, a
r
c
=
4
2
.
9
for the 5DLM, and a
r
c
=
1
1
6
.
9
for the 7DLM. In association with stable nontrivial critical points that may lead to steady-state solutions, the appearance of chaotic orbits indicates the important role of a saddle point at the origin in producing the sensitive dependence of solutions on initial conditions. The 9DLM displays the coexistence of chaotic and steady-state solutions at moderate Rayleigh parameters and the coexistence of limit cycle and steady-state solutions at large Rayleigh parameters. The first kind of coexistence appears within a smaller range of Rayleigh parameters in lower-dimensional LMs (i.e.
2
4
.
0
6
<
r
<
2
4
.
7
4
within the 3DLM) but in a wider range of Rayleigh parameters within the 9DLM (i.e.
6
7
9
.
8
<
r
<
1
0
5
8
). The second kind of coexistence has never been reported in high-dimensional Lorenz systems.
Permanent magnets are a class of critical materials for information storage, energy storage, and other magneto‐electronic applications. Compared with conventional bulk magnets, magnetic nanoparticles ...(MNPs) show unique size‐dependent magnetic properties, which make it possible to control and optimize their magnetic performance for specific applications. The synthesis of MNPs has been intensively explored in recent years. Among different methods developed thus far, chemical synthesis based on solution‐phase reactions has attracted much attention owing to its potential to achieve the desired size, morphology, structure, and magnetic controls. This Minireview focuses on the recent chemical syntheses of strongly ferromagnetic MNPs (Hc>10 kOe) of rare‐earth metals and FePt intermetallic alloys. It further discusses the potential of enhancing the magnetic performance of MNP composites by assembly of hard and soft MNPs into exchange‐coupled nanocomposites. High‐performance nanocomposites are key to fabricating super‐strong permanent magnets for magnetic, electronic, and energy applications.
Hard magnetic nanomaterials: Chemical synthesis of magnetic nanoparticles has received great attention owing to its advantages, which lead to the desired control of the magnetic properties. This Minireview highlights recent developments in the chemical synthesis of hard magnetic nanoparticles and exchange‐coupled nanocomposites for permanent magnet applications.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
High‐performance lead‐free piezoelectric materials are in great demand for next‐generation electronic devices to meet the requirement of environmentally sustainable society. Here, ultrahigh ...piezoelectric properties with piezoelectric coefficients (d33 ≈700 pC N−1, d33* ≈980 pm V−1) and planar electromechanical coupling factor (kp ≈76%) are achieved in highly textured (K,Na)NbO3 (KNN)‐based ceramics. The excellent piezoelectric properties can be explained by the strong anisotropic feature, optimized engineered domain configuration in the textured ceramics, and facilitated polarization rotation induced by the intermediate phase. In addition, the nanodomain structures with decreased domain wall energy and increased domain wall mobility also contribute to the ultrahigh piezoelectric properties. This work not only demonstrates the tremendous potential of KNN‐based ceramics to replace lead‐based piezoelectrics but also provides a good strategy to design high‐performance piezoelectrics by controlling appropriate phase and crystallographic orientation.
Textured (K,Na)NbO3‐based piezoelectric ceramics with ultrahigh piezoelectric properties (d33 ≈700 pC N−1, d33* ≈980 pm V−1, kp ≈76%) are prepared through a template grain growth method. The intrinsic piezoelectric anisotropy, large lattice distortion, the existence of intermediate monoclinic phase and nanodomain structure are considered likely to be responsible for the excellent piezoelectric properties. These results highlight the textured (K,Na)NbO3‐based lead‐free ceramics for piezoelectric device applications.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Platinum‐catalyzed formal 5+2 and 4+2 annulations of isoxazoles with heterosubstituted alkynes enabled the atom‐economical synthesis of valuable 1,3‐oxazepines and 2,5‐dihydropyridines, respectively. ...Importantly, this Pt catalysis not only led to unique reactivity dramatically divergent from that observed under Au catalysis, but also proceeded via unprecedented α‐imino platinum carbene intermediates.
Gold's deviant relative: Platinum‐catalyzed formal 5+2 and 4+2 annulations of isoxazoles and heterosubstituted alkynes provided valuable 1,3‐oxazepines and 2,5‐dihydropyridines (see scheme). This reactivity deviates dramatically from that observed under gold catalysis and involves the generation of an α‐imino platinum carbene. A computational study provided evidence for the proposed mechanism of this unusual tandem sequence.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
PDF
