Fabrication of smart cutting tools with embedded optical fiber sensors using combined laser solid freeform fabrication and moulding techniques

To realize the concept of smart tools, embedding of fiber optic sensors in the metallic structure of a cutting tool with combined laser solid freeform fabrication (LSFF) and moulding is presented in this paper. Metallic parts with embedded optical fiber sensors are capable of monitoring physical parameters like force and temperature. These sensors are advantageous relative to other conventional electric and electromagnetic sensors due to their light weight, immunity to external electromagnetic fields, small size, long-term durability, and long-range linearity. In the present work, the optical fibers (e.g., fiber Bragg grating sensor, single-mode fiber optics) are moulded under tensile forces within a mild steel casing filled by Sn–Pb to fabricate a protective layer around them. Afterwards, LSFF is utilized to deposit tungsten carbide reinforced in cobalt (WC–Co) on the surface of the mild steel component. The performance results, in which the sensor exposed to a light bandwidth, show that the maximum light power loss after embedding is about 21% implying that the fiber is not damaged during the embedding process. Also, the sensor output has a linear characteristic under compression loadings indicating that the debonding of the fiber from the protective layer is not probable. The produced samples are examined by scanning electron microscopy and X-ray diffraction to assess the physical properties of the tool. Microstructural images reveal no cracks and porosity around the fiber indicating a good bonding between the fiber and the surrounding media. Material characterizations of the manufactured tool are also discussed.     

Survey reactivity of 2-aminopyridine and Meldrum’s acid in the presence of aryl glyoxals or aryl aldehydes; ethyl 2-(3-aryl imidazo[1,2-a]pyridin-2-yl)acetates versus ethyl 3-aryl-3-(pyridin-2-ylamino)propanoates

Research on Chemical Intermediates - The aim of present investigation is survey reactivity of 2-aminopyridine and Meldrum’s acid in the presence of aryl glyoxals or aryl aldehydes. The ethyl...     

Exceedingly Facile Ph?X Activation (X=Cl,Br, I) with Ruthenium(II): Arresting Kinetics,Autocatalysis, and Mechanisms

[(Ph₃P)₃Ru(L)(H)₂] (where L=H₂ ( 1 ) in the presence of styrene, Ph₃P ( 3 ), and N₂ ( 4 )) cleave the Ph X bond (X=Cl, Br, I) at RT to give [(Ph₃P)₃RuH(X)] ( 2 ) and PhH. A combined experimental and DFT study points to [(Ph₃P)₃Ru(H)₂] as the reactive species generated upon spontaneous loss of L from 3 and 4 . The reaction of 3 with excess PhI displays striking kinetics which initially appears zeroth order in Ru. However mechanistic studies reveal that this is due to autocatalysis comprising two factors: 1) complex 2 , originating from the initial PhI activation with 3 , is roughly as reactive toward PhI as 3 itself; and 2) the Ph I bond cleavage with the just‐produced 2 gives rise to [(Ph₃P)₂RuI₂], which quickly comproportionates with the still‐present 3 to recover 2 . Both the initial and onward activation reactions involve PPh₃ dissociation, PhI coordination to Ru through I, rearrangement to a η²‐PhI intermediate, and Ph I oxidative addition.     

Single Peptide Backbone Surrogate Mutations to Regulate Angiotensin GPCR Subtype Selectivity

Mutating the side-chains of amino acids in a peptide ligand, with unnatural amino acids, aiming to mitigate its short half-life is an established approach. However, it is hypothesized that mutating specific backbone peptide bonds with bioisosters can be exploited not only to enhance the proteolytic stability of parent peptides, but also to tune its receptor subtype selectivity. Towards this end, four [Y]⁶-Angiotensin II analogues are synthesized where amide bonds have been replaced by 1,4-disubstituted 1,2,3-triazole isosteres in four different backbone locations. All the analogues possessed enhanced stability in human plasma in comparison with the parent peptide, whereas only two of them achieved enhanced AT₂R/AT₁R subtype selectivity. This diversification has been studied through 2D NMR spectroscopy and unveiled a putative more structured microenvironment for the two selective ligands accompanied with increased number of NOE cross-peaks. The most potent analogue, compound 2 , has been explored regarding its neurotrophic potential and resulted in an enhanced neurite growth with respect to the established agent C21.     

Two families of scaled three-term conjugate gradient methods with sufficient descent property for nonconvex optimization

Numerical Algorithms - In this paper, we present two families of modified three-term conjugate gradient methods for solving unconstrained large-scale smooth optimization problems. We show that our...     

Bifurcation of limit cycles in small perturbations of a hyper-elliptic Hamiltonian system with two nilpotent saddles

In this paper we study the first-order Melnikov function for a planar near-Hamiltonian system near a heteroclinic loop connecting two nilpotent saddles. The asymptotic expansion of this Melnikov function and formulas for the first seven coefficients are given. Next, we consider the bifurcation of limit cycles in a class of hyper-elliptic Hamiltonian systems which has a heteroclinic loop connecting two nilpotent saddles. It is shown that this system can undergo a degenerate Hopf bifurcation and Poincarè bifurcation, which emerges at most four limit cycles in the plane for sufficiently small positive ε. The number of limit cycles which appear near the heteroclinic loop is discussed by using the asymptotic expansion of the first-order Melnikov function. Further more we give all possible distribution of limit cycles bifurcated from the period annulus.     

Evaluation of UiO‐66 metal organic framework as an effective sorbent for Curcumin's overdose

Metal organic frameworks (MOFs) UiO‐66 (UiO stands for University of Oslo) and NH₂‐UiO‐66 were prepared and characterized as sorbent (antidotal agents) for curcumin (CUR) adsorption. The structure of products were characterized by X‐ray powder diffraction (XRD), Field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Attenuated Total Reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR), and N₂ adsorption–desorption measurements. FESEM showed NH₂‐UiO‐66 displayed symmetrical crystals with triangular base pyramid morphology, with the particle size around 100 nm and uniform size distribution. Adsorption capacities of CUR/MOFs with different mass ratios in the feed were investigated in the present study, and this investigation revealed that when the CUR/MOFs with mass ratio was around 0.4, the absorption capacity of NH₂‐UiO‐66 had tended to maximum. Although, functionalization reduced the specific surface area and free volume, introducing polar amine groups could improve the affinity of NH₂‐UiO‐66 respect to CUR. Kinetic studies showed that the kinetic data are well fitted with the pseudo‐ second‐order model. MTT assay revealed that MOFs at the concentration range of 0–560 μg/ml had no cytotoxic effect on the Human Foreskin Fibroblast normal cell line (HFF‐2). These results suggest that these MOFs could be safe as sorbent for adsorb CUR from the body.     

Study of acoustic bubble cluster dynamics using a lattice Boltzmann model

The search for the development of a reliable mathematical model for understanding bubble dynamics behavior is an ongoing endeavor.A long list of complex phenomena underlies the physics of this problem.In the past decades,the lattice Boltzmann method has emerged as a promising tool to address such complexities.In this regard,we have applied a 121-velocity multiphase lattice Boltzmann model to an asymmetric cluster of bubbles in an acoustic field.A problem as a benchmark is studied to check the consistency and applicability of the model.The problem of interest is to study the deformation and coalescence phenomena in bubble cluster dynamics,as well as the screening effect on an acoustic multibubble medium.It has been observed that the LB model is able to simulate the combination of the three aforementioned phenomena for a bubble cluster as a whole and for every individual bubble in the cluster.