Onset and stabilization of delay-induced instabilities in piezoelectric digital vibration absorbers

The stability of a piezoelectric structure controlled by a digital vibration absorber emulating a shunt circuit is investigated in this work. The formalism of feedback control theory is used to demonstrate that systems with a low electromechanical coupling are prone to delay-induced instabilities entailed by the sampling procedure of the digital unit. An explicit relation is derived between the effective electromechanical coupling factor and the maximum sampling period guaranteeing a stable controlled system. Since this sampling period may be impractically small, a simple modification procedure of the emulated admittance of the shunt circuit is proposed in order to counteract the effect of delays by anticipation. The theoretical developments are experimentally validated on a clamped-free piezoelectric beam.

A Smart Assistance System for Visually Impaired People

Resolving the problems of individuals with Visual, Hearing, and Vocal Impairment through a solitary serving framework could be a tough task. Various current investigations focus on the resolution of the problems of 1 of them on top of challenges however not all. The work centers around chase down a noteworthy procedure that guides the externally weakened by permitting them to listen to what's self-addressed as text and it's accomplished by the tactic that catches the image through a camera and converts the content accessible as voice signals. This planned framework provides a path to people with Hearing weakening to image scan that is in morphology by discourse to message modification procedure and that we, in addition, provides a route to the vocally disabled to handle their voice by the guide of text to voice transformation strategy. each one of those 3 arrangements was regulated to be in an exceedingly solitary exceptional framework. each one of those exercises consists of the employment of Raspberry Pi. The outwardly barred individual's unit of measurement is helped by the cycle whereby the image to text and text to discourse is given by the Tesseract OCR (online character acknowledgment). The deaf individuals assist with the cycle of associate application that creates them grasp what the individual says is also shown attributable to the message. Vocally hindered individuals can pass on their message by text. Therefore totally different individuals will hear the message in an exceeding speaker.

The association of myocardial injury during chronic total occlusion percutaneous coronary intervention with lesion complexity and treatment strategy

Background Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) is associated with procedural myocardial injury (PMI), and adverse long-term clinical outcomes [1–4].CTO lesion complexity is quantified using established scores [5–8], with high complexity known to determine the need for dissection and re-entry techniques and the retrograde approach, which are then associated with a higher incidence of procedural complications [9,10]. If CTO recanalization is unsuccessful, a modification procedure can be performed, with the intention to improve subsequent procedural success [11–14]. There are limited data on the association between PMI, CTO complexity and treatment strategy. Purpose To report the incidence of myocardial injury following CTO PCI, and assess whether this is associated with lesion complexity, crossing strategy, or the use of a modification procedure. Methods This is a retrospective analysis of consecutive elective CTO PCI procedures performed at a single centre in Norway between January 2020 and March 2021. High-sensitivity troponin T (hsTnT) was measured pre and 12–18 hours post-procedure. Myocardial injury defined as a post-procedure elevation of hsTnT >5x 99th percentile URL with a normal baseline value or a rise >20% with elevated pre-procedure hsTnT. CTO complexity was described using the J-CTO, PROGRESS, RECHARGE and EuroCASTLE scores [5–8]. Procedures were classified as technical successful or unsuccessful according to CTO academic research consortium (CTO-ARC)criteria [15], and further categorised according to final crossing strategy [antegrade wiring (AW), antegrade dissection re-entry (ADR), retrograde wiring (RW) or retrograde dissection re-entry (RDR)]. If unsuccessful they were further categorised as “failure” or “unplanned modification procedure”. A “planned modification procedure” defined as intentional antegrade modification of the occlusive segment with no attempt to complete CTO crossing. Results We analysed 122 CTO PCI procedures. Mean J-CTO, PROGRESS, RECHARGE, EuroCASTLE scores were 2.7, 1.2, 3.0 and 3.1 respectively. Technical success during the index procedure was 75%. An unplanned or planned modification procedure was performed in 16% and 2% of cases, respectively. Technical failure occurred in 7% of cases. Myocardial injury occurred in 65% of all procedures (78% of failed procedures, 64% of successful procedures, 63% of unplanned and none of 3 planned CTO modification procedures). The mean hs-TnT according to treatment strategy and outcomes are reported in Table 1. The relationship between the CTO complexity scores and hs-TnT are illustrated in Figure 1. Conclusions Myocardial injury is common during CTO PCI, particularly with more complex anatomy, requiring the retrograde approach or an unplanned modification procedure. A prospective analysis of whether myocardial injury can be avoided using a planned investment procedure in high complexity cases is currently being conducted. FUNDunding Acknowledgement Type of funding sources: None.

Improvement of ligand-free modification strategy to obtain water-stable up-converting nanoparticles with bright emission and high reaction yield

Water-dispersible up-converting nanoparticles (UCNPs) are known to be very effective in biomedical applications. Research groups have paid special attention to the synthesis of hydrophilic UCNPs with good physicochemical properties. Being aware of this, we decided to improve the ligand-free modification method of OA-capped NaYF4:Yb3+,Er3+/NaYF4 UCNPs prepared by precipitation in high-boiling-point solvents as the thus-far reported methods do not provide satisfactory results. Different molarities of hydrochloric acid and various mixing times were selected to remove the organic ligand from the NPs’ surface and to discover the most promising modification approach. Highly water-stable colloids were obtained with a very high reaction yield of up to 96%. Moreover, the acid treatment did not affect the morphology and the size of the product. All of the crystals exhibited a bright up-conversion emission under 975-nm excitation, which confirmed the two-photon excitation and effective energy transfer between the used dopant ions. Thus, we could establish the most successful ligand-free modification procedure.

“Exhaustive” Baeyer-Villiger Oxidation of Poly(Methyl Vinyl Ketone) and Its Copolymers

The development of “exhaustive” (nearly quantitative) post-modification reactions relies heavily on the efficiency of their corresponding small-molecule protocols. However, the direct translation of existing small-molecule protocols into post-polymerization modifications were often troublesome due to undesired side reactions. For example, the development of an “exhaustive” BaeyerVilliger (BV) post-modification using existing small-molecule BV protocols suffered from a lack of reactivity or significant chain scission. Herein, we demonstrate that a careful re-optimization of a small-molecule transformation on a polymer substrate allowed us to overcome such challenges, thereby enabling an “exhaustive” BV post-polymerization modification. Furthermore, a one-pot copolymerization/“exhaustive” BV post-modification procedure was developed to produce copolymers of vinyl acetate (VAc) and more activated monomers (MAMs) in a convenient and scalable manner. This user-friendly methodology provides a general access to synthetically challenging poly(VAc-co-MAM)s including both statistical and narrow-dispersed block copolymers and could greatly facilitate the exploration of applications with such materials.

A new density-modification procedure extending the application of the recent |ρ|-based phasing algorithm to larger crystal structures

The incorporation of the new peakness-enhancing fast Fourier transform compatible ipp procedure (ipp = inner-pixel preservation) into the recently published SM algorithm based on |ρ| [Rius (2020). Acta Cryst A76, 489–493] improves its phasing efficiency for larger crystal structures with atomic resolution data. Its effectiveness is clearly demonstrated via a collection of test crystal structures (taken from the Protein Data Bank) either starting from random phase values or by using the randomly shifted modulus function (a Patterson-type synthesis) as initial ρ estimate. It has been found that in the presence of medium scatterers (e.g. S or Cl atoms) crystal structures with 1500 × c atoms in the unit cell (c = number of centerings) can be routinely solved. In the presence of strong scatterers like Fe, Cu or Zn atoms this number increases to around 5000 × c atoms. The implementation of this strengthened SM algorithm is simple, since it only includes a few easy-to-adjust parameters.

“Exhaustive” Baeyer-Villiger Oxidation of Poly(Methyl Vinyl Ketone) and Its Copolymers

Poly(vinyl acetate) and its copolymers represent an important class of commodity polymers. However, the preparation of copolymers of vinyl acetate (VAc) and more activated monomers (MAMs) <i>via</i> copolymerization is greatly restricted due to their disparate reactivities. Issues relating to reactivity ratios remain a fundamental challenge in copolymerization. Herein, we describe a post-polymerization modification approach using poly(methyl vinyl ketone-<i>co</i>-MAM)s as substrates to access synthetically challenging poly(VAc-<i>co</i>-MAM)s. Although the direct translations of existing small-molecule Baeyer-Villiger (BV) protocols into a post-polymerization modification method failed, a mechanism-guided multi-parameter optimization on polymer substrates disclosed a set of unique “exhaustive” BV protocols which enabled a nearly quantitative functionalization without obvious chain scission or cross-linking. Furthermore, a one-pot copolymerization/“exhaustive” BV post-modification procedure was developed to produce such copolymers in a convenient and scalable manner. This user-friendly methodology is able to access diverse poly(VAc-<i>co</i>-MAM)s including both statistical and narrow-dispersed block copolymers and could greatly facilitate the exploration of applications with such materials.

“Exhaustive” Baeyer-Villiger Oxidation of Poly(Methyl Vinyl Ketone) and Its Copolymers

Poly(vinyl acetate) and its copolymers represent an important class of commodity polymers. However, the preparation of copolymers of vinyl acetate (VAc) and more activated monomers (MAMs) <i>via</i> copolymerization is greatly restricted due to their disparate reactivities. Issues relating to reactivity ratios remain a fundamental challenge in copolymerization. Herein, we describe a post-polymerization modification approach using poly(methyl vinyl ketone-<i>co</i>-MAM)s as substrates to access synthetically challenging poly(VAc-<i>co</i>-MAM)s. Although the direct translations of existing small-molecule Baeyer-Villiger (BV) protocols into a post-polymerization modification method failed, a mechanism-guided multi-parameter optimization on polymer substrates disclosed a set of unique “exhaustive” BV protocols which enabled a nearly quantitative functionalization without obvious chain scission or cross-linking. Furthermore, a one-pot copolymerization/“exhaustive” BV post-modification procedure was developed to produce such copolymers in a convenient and scalable manner. This user-friendly methodology is able to access diverse poly(VAc-<i>co</i>-MAM)s including both statistical and narrow-dispersed block copolymers and could greatly facilitate the exploration of applications with such materials.

Selective Production of Phenol on Bifunctional, Hierarchical ZSM-5 Zeolites

Mono- and bimetallic Ni-, Ru- and Pt-modified hierarchical ZSM-5 materials were prepared by impregnation technique and characterized by X-ray diffraction (XRD), N2 physisorption, temperature-programmed reduction (TPR–TGA), ATR–FTIR and solid state NMR spectroscopy. Formation of finely dispersed nickel, ruthenium and platinum species was observed on the bimetallic catalysts. It was found that the peculiarity of the used zeolite structure and the modification procedure determine the type of formed metal oxides and their dispersion and reducibility. The samples’ acidity was studied via FTIR spectroscopy of adsorbed pyridine. The changes in the zeolite structure were studied via solid-state NMR spectroscopy. The catalysts were investigated in a gas-phase hydrodeoxygenation, transalkylation and dealkylation reaction of model lignin derivative molecules for phenol production.