Rupture Of Ring Research Articles

Transobturator-cable-fixation in pelvic ring injuries with symphyseal disruption - a last resort?

The role of transobturator-cable-fixation (TOCF) in traumatic symphyseal rupture of the pelvic ring remains unclear. This case series aims to evaluate TOCF in complex and revision cases in pelvic surgery. A retrospective analysis of a chronological case series was conducted, studying pelvic fractures stabilized using TOCF between January 2006 and December 2022. The variables considered included age, gender, fracture classification, Injury Severity Score (ISS), Body Mass Index (BMI), trauma mechanism, time to surgery, fixation technique, hospital duration, complications, status on discharge (Glasgow Outcome Scale; GOS), follow-up time and indication for the use of TOCF. All patients (N = 7) were male with a mean age of 64 years and a mean BMI of 29. The mean ISS was 45, with the lowest ISS of 25, indicating that only polytraumatized patients were included. Two anterior-posterior-compression-, four lateral-compression-, and one vertical-shear-pelvic-injury were identified. TOCF was added in six cases to support symphyseal plating and in one case to external fixation. The mean hospital stay was 49 days and the mean follow-up duration was 8.5 months. No complications associated with TOCF were observed during the surgical procedure or follow-up. TOCF showed no procedure-associated complications and effectively supported symphyseal healing in all cases. The main indications were obesity, poor bone quality in elderly patients, and revision cases. TOCF could be considered as a last treatment option in open-book pelvic injuries where plating or external fixation is at risk to fail.

Mechanism of the Low-Temperature Organic Removal from Imidazolium-Containing Zeolites by Ozone Treatment: Fluoride Retention in Double-4-Rings.

For zeolites synthesized using imidazolium cations, the organic matter can be extracted at very low temperatures (100 °C) using ozone. This is possible for zeolites with 12-ring or larger pores but requires higher temperatures in medium-pore zeolites. The first chemical events in this process occur fast, even at room temperature, and imply the loss of aromaticity likely by the formation of an adduct between ozone and the imidazole ring through carbons C4 and C5. Subsequent rupture of the imidazole ring provides smaller and more flexible fragments that can desorb more readily. This process has been studied experimentally, mainly through infrared spectroscopy, and theoretically by density functional theory. Amazingly, fluoride anions occluded in the small double-four-ring units (d4r) during the synthesis remain inside the cage throughout the whole process when the temperature is not too high (≤150 °C). However, fluoride in larger cages in MFI ends up bonded to silicon in penta or hexacoordinated units, likely out of the cages, after ozone treatment at 150 °C. For several germanosilicate zeolites, the process allows their subsequent degermanation to yield stable high-silica zeolites. Quaternary ammonium cations require harsher conditions that eventually also extract fluoride from zeolite cages, including the d4r unit.

CoFe2O4 as a source of Co(II) ions for imidacloprid insecticide oxidation using peroxymonosulfate: Influence of process parameters and surface changes

Nanometric cobalt magnetic ferrite (CoFe2O4) synthesized by distinct methods was used for in situ chemical activation of peroxymonosulfate (PMS) under neutral conditions to oxidize imidacloprid (IMD) insecticide. The effect of CoFe2O4 load (0.125–1.0 g L−1) and PMS concentration (250–1000 μM) was investigated as well as the influence of phosphate buffer and Co(II) ions. PMS activation by Co(II) ions, including those leached from CoFe2O4 (>50 μg L−1), exhibited a strong influence on IMD oxidation and, apparently, without substantial contributions from the solid phase. Within the prepared solid materials (i.e., using sol-gel and co-precipitation methods), high oxidation rates (ca. 0.5 min−1) of IMD were attained in ultrapure water. Phosphate buffer had no significant influence on the IMD oxidation rate and level, however, its use and solution pH have shown to be important parameters, since higher PMS consumption was observed in the presence of buffered solutions at pH 7. IMD byproducts resulting from hydroxylation reactions and rupture of the imidazolidine ring were detected by mass spectrometry. At optimum conditions (0.125 g L−1 of CoFe2O4 and 500 μM of PMS), the CoFe2O4 nanoparticles exhibited an increase in the charge transfer resistance and an enhancement in the surface hydroxylation after PMS activation, which led to radical (HO● and SO4●–) and nonradical (1O2) species. The latter specie led to high levels of IMD oxidation, even in a complex water matrix, such as simulated municipal wastewater at the expense of one-order decrease in the IMD oxidation rate.

High energy barrier hydroxyl radical dissociation mechanism of a low shock sensitivity dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) explosive.

As a representative of the new generation of high-energy explosives, TKX-50 has attracted widespread attention due to its remarkably low sensitivity toward shock. However, the reported decomposition barriers of TKX-50 (∼37 kcal mol-1) are comparable to those of commonly used explosives. The mechanism of its low shock sensitivity remains unclear. In this study, using an ab initio molecular dynamics method combined with a multiscale shock simulation technique and transition state calculations (at the B2PLYP-D3/Def2TZVP level), we discovered an unconventional reaction pathway of TKX-50 under shock, and its rate-controlling step is the dissociation of the hydroxyl radical (OH) from the anion ring after proton transfer, followed by ring rupture and the production of H2O and N2. The barrier for this OH dissociation reaction is as high as 51.9 kcal mol-1. In contrast, under thermal stimuli, TKX-50 prefers to open rings directly after proton transfer without losing the OH. The corresponding barrier is 35.4 kcal mol-1, which is in good agreement with previous studies. The reason for the unconventional reaction pathway of TKX-50 under shock may be the suppression of anion ring opening in thermal decomposition by steric hindrance upon shock compression. In addition, the dominant N2 generation pathway under shock releases less energy than pyrolysis which further explains the low shock sensitivity of TKX-50. This study comprehensively elucidates the different reaction mechanisms of TKX-50 under thermal and shock conditions and proposes a crucial reaction pathway leading to its low shock sensitivity. These findings will contribute to the understanding and application of tetrazole anionic energetic salts.

Pseudoexfoliative Syndrome in Cataract Surgery-A Quality Register Study and Health Economic Analysis in the Split-Dalmatia County, Croatia.

To investigate the impact of pseudoexfoliation (PEX) syndrome on intraoperative phacoemulsification (PHACO) parameters and assess the economic cost of PHACO surgery for cataracts in patients with and without PEX syndrome. This was a retrospective quality register study on 5889 patients (6236 eyes) who underwent PHACO cataract surgery in the Eye Clinic, Clinical Hospital Centre Split, Croatia, over a 7-year period (May 2015 to December 2022), in accordance with the Guidelines of the Helsinki Declaration and approval from the Research Ethics Committee of the University Hospital Centre Split, Croatia. Inclusion criteria were patients with either presenile or senile cataract or cataract related to PEX syndrome who undertook PHACO procedure by the same experienced surgeon using the same PHACO device (Infiniti Vision System, Alcon Laboratories, Inc., Fort Worth, TX, USA). Eyes were categorized according to PEX presence- (PEX group) or absence (Group without PEX). The following recorded data about intraoperative PHACO parameters were collected: Cumulative Dissipated Energy (CDE), Ultrasound total time, PHACO time, torsional time, aspiration time, estimated fluid used, and duration of the surgical procedure. In the economic analysis, all PHACO parameters were considered, with a specific focus on the duration of the surgical procedure, costs associated with additional medical materials and devices, complications during surgery, and surgery procedure Diagnosis-Related Group (DRG) codes. A total of 4535 cases were eligible for inclusion in the study, 278 (6.13%) were diagnosed with PEX and 4257 (93.87%) had no PEX. Significantly higher PHACO parameters were observed in the PEX group. Similarly, a statistically significant increase in the values of all PHACO parameters was observed with the increase in nuclear lens density. Intraoperative complications were more frequent in the PEX group. Zonular weakness requiring the use of a capsular tension ring (CTR) and posterior capsular rupture occurred 30 and 13 times more often, respectively, in the PEX group. The expected cost of the PHACO procedure was found to be 1.4 times higher in patients with PEX, compared to those without PEX, for all types of nuclear cataract. All PHACO parameters are significantly higher in patients with PEX. The costs associated with PHACO surgery for cataracts are greater for patients with PEX and are not covered by the present DRG codes, which highlights the need to accordingly adjust the DRGs for PHACO procedures in PEX patients, in order to maintain the quality of healthcare provided for these vulnerable patients.

Variation of interception efficiency and transformation to natural glucocorticoids in three texture reclaimed water receiving riverbeds

BackgroundThe efficacy of the interception and purification mechanism for low-dose toxic contaminants in riverbeds, which serve as a link between surface water and groundwater, is of paramount importance in ensuring groundwater safety, particularly considering the replenishment of reclaimed water. The specific objective of this work is to identify the variation of interception efficiency and transformation to natural glucocorticoids in three texture reclaimed water receiving riverbeds. MethodsHerein, an experimental percolation platform was set up to simulate hydrocortisone (HC) migration and biotransformation during the reclaimed water infiltration process through three typical types of riverbeds (silty clay (SC), loam (L) and sand (S)). Significant findingsThe attenuation of HC in time dimension and longitudinal direction was consistent with the two compartment first-order kinetic model, with decay rate constant greater than -0.031 m−1 and 2.71 d−1 in spatial and temporal distribution. The SC riverbed enhanced 36.36 % HC removal due to adsorption and microbial transformation. Furthermore, the major metabolic pathways of side chain oxidation and ring rupture were significantly enhanced due to the increasing diversity and relative abundance of the functional bacteria present in SC. The enrichment of functional genera, Stenotrophomonas and Sphingomonas contributed to the biotransformation enhancement. pH and TOC played the most significant role to the difference of migration and metabolism of HC. Moreover, pore volume was the primary factor leading to varying adsorption of three types of riverbeds for HC. The simulation results with HYDRUS showed that the ecological risk level of HC in L and S were 6.5 times higher than SC after 50 years infiltration. Therefore, future challenges and prospects concerning pollution control and enhancement measures should be pay attention to the physicochemical characteristics of various riverbeds.

Enhanced removal of estrogens from simulated wastewater by biochar supported nanoscale zero-valent iron: performance and mechanism

The intensification of estrogen non-point source pollution has drawn global attention due to their contribution to ecological environment problems worldwide, and it is critical to develop effective, economic and eco-friendly methods for reducing estrogens pollution. To address the agglomeration and oxidation of nano zero-valent iron (nZVI), biochar-nanoscale zero-valent iron composite (nZVI-biochar) could be a feasible choice for estrogens removal. This study summarized biochar and nZVI-biochar preparation, characterization, and unusual applications for estrone (E1), 17β-estradiol (E2), and estriol (E3) removal. The properties of biochar and nZVI-biochar in characterization, effects of influencing factors on the removal efficiency, adsorption kinetics, isotherm and thermodynamics were investigated. The experiment results showed that nZVI-biochar exhibited the superior removal performance for estrogens pollutants compared to biochar. Based on the quasi-second-order model, estrogens adsorption kinetics were observed, which supported the mechanism that chemical and physical adsorption existed simultaneously on estrogens removal. The adsorption isotherm of estrogens could be well presented by the Freundlich model and thermodynamics studies explained that nZVI-biochar could spontaneously remove estrogens pollutants and the main mechanisms involved π-π interaction, hydrophobic interaction, hydrogen bonding and degradation through ring rupture. The products analyzed by GC–MS showed that estrogens degradation was primarily attributed to the benzene ring broken, and Fe3+ promoted the production of free radicals, which further proved that nZVI-biochar had the excellent adsorption performances. Generally, nZVI-biochar could be employed as a potential material for removing estrogens from wastewater.Graphical

Conformational changes during invitro balloon fracture of internal aortic annuloplasty ring.

HAART 300 300 (BioStable Science and Engineering, Inc) aortic annuloplasty rings restore physiologic annular geometry during aortic valve repair. Transcatheter valve-in-ring implantation is appealing for recurrent valve dysfunction but may necessitate balloon fracture of downsized annuloplasty rings. We characterized the feasibility of ring fracture and changes in ring geometry preceding fracture. The 19-mm, 21-mm, and 23-mm HAART 300 annuloplasty rings were obtained, and 23-mm, 24-mm, 25-mm, and 26-mm valvuloplasty balloons were obtained. Under continuous fluoroscopy and video recording, a 23-mm balloon was inflated within a 19-mm ring at 1atm/s until ring fracture or balloon failure occurred. If balloon failure occurred, experiments were sequentially repeated with 1-mm upsized balloons until ring fracture occurred or no larger-sized balloons were available. Upon balloon inflation, all rings exhibited an irreversible conformational change from an elliptical, annular geometry to a circular shape with ring posts flaring outward. A 23-mm balloon burst at 21atm without fracturing the 19-mm ring. The 24-mm balloon fractured the 19-mm ring at 15atm. Likewise, a 24-mm balloon ruptured at 18atm without fracturing the 21-mm annuloplasty ring. A 25-mm balloon fractured the 21-mm ring at 18atm. Finally, a 26-mm balloon burst at 20atm without fracturing a 23-mm annuloplasty ring, but it did elicit the confirmational changes described. All fractures occurred along the upslope of a ring post. The exposed metal frame was visible after the 21-mm ring fracture. Fracture of HAART 300 aortic annuloplasty rings is possible with an oversized, high-pressure balloon. However, the geometrical changes in the ring and subsequent rupture of its fabric covering may be obstacles to safe, invivo ring fracture.

Deposition and morphology of direct current plasma-polymerized aniline

Plasma polymerization is a simple, solvent-free, dry process that involves vaporizing a monomer and ionizing them to the plasma state. This study reports the plasma polymerization of aniline in a direct current glow discharge. Aniline was introduced into a vacuum chamber and plasma-polymerized onto an indium-doped tin oxide/glass substrate at varying discharge potentials and deposition times. The resulting plasma-polymerized aniline films were in the leucoemeraldine form, as evidenced by UV-Vis and infrared spectral analyses. Monocarbon species that are products of the aromatic ring rupture were observed from the optical emission spectra of the discharge. The films reveal a smooth, pinhole-free surface across different process parameters. The film thickness from the 200 to 600 nm range presents a linear relationship with respect to the duration of deposition. The deposition rate also increased and has a good linear relationship when the discharge potential was varied.

Influence of Coordination Geometry on the Ring Opening of Benzoxazine: Oxidovanadium(V), Dioxidomolybdenum(VI) and Dioxidotungsten(VI) Complexes of Benzoxazine Based Ligands and their Bio Inspired Catalytic Applications

AbstractMono benzoxazine appended N‐capped amino bis(disubstitutedphenol) ligands [II(a–c)] upon reaction with VVO(OEt)3 in a 1 : 1 molar ratio in EtOH/MeOH give [{VVO}en(3,5‐dtbb)3] (1), [{VVO}en(3‐tb,5‐mb)3] (2) and [{VVO}en(3,5‐dmb)3] (3). During the reaction, the benzoxazine ring opens with the loss of methylene group and the newly formed ligands, N,N‐bis(2‐hydroxy‐3,5‐disubstitutedbenzyl)‐N’‐2‐hydroxy‐3,5‐disubstituted benzyledene‐1,2‐diaminoethane [III(a–c)], behave as tribasic pentadentate in these complexes. Under similar conditions, when [MVIO2(acac)2] (M=Mo or W; Hacac=acetylacetone) reacts with II(a–c), these ligands retain their identity and form cis‐[MVIO2] complexes, [{MoVIO2}{en(3,5‐dtbb)2(6,8‐dtbbenzox)}] (4), [{MoVIO2}{en(3‐tb,5‐mb)2(6‐tb,8‐mbbenzox)}] (5) and [{MoVIO2}{en(3,5‐dmb)2(6,8‐dmbenzox)}] (6), [{WVIO2}{en(3,5‐dtbb)2(6,8‐dtbbenzox)}] (7), and [{WVIO2}{en(3‐tb,5‐mb)2(6‐tb,8‐mbbenzox)}] (8). However, the benzoxazine ring ruptures in case of ligand IIc under these conditions and form [{WVIO2}{en(3,5‐dmb)3}] (10), similar to complexes 1–3. Complex [{WVIO2}{en(3,5‐dmb)2(6,8‐dmbenzox)}] (9), having structure similar to 4–8, could only be obtained when the reaction was carried out in toluene. Not only 9, even complexes 4–8 can be isolated in toluene. Rupturing of both benzoxazine rings has also been experienced when ligands 1,2‐bis(6,8‐disubstitutedbenzo[e][1,3]oxazin‐3(4H)‐yl)ethane [I(a–c)] react with [MVIO2(acac)2] (M=Mo or W) in MeOH and give salan type complexes [(MVIO2)en(3,5‐dtbb)2] [M=Mo (11), M=W (14)], [(MVIO2)en(3‐tb,5‐mb)4] [M=Mo (12), M=W (15)] and [(MVIO2)en(3,5‐dmb)4] [M=Mo (13), M=W (16)]. Complexes 1–9 have been used as catalyst for the multicomponent Biginelli reaction for the synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones (DHPMs) and oxidative bromination of phenol derivatives.

Thermal mixing characteristics of T-junction incident along central axis based on Large-Eddy simulations

A large eddy simulation model was used to explore the temperature mixing characteristics of a T-junction in which a branch pipe extends into the main and the branch fluid is injected along the central axis of the main pipe. The influence of the incident velocity of the branch tube on the temperature fluctuation of the fluid mixing is considered. In the main mixing region, the dimensionless time-averaged temperature（T∗¯）is positively related to the dimensionless root mean square（Trms∗）, while the connecting pipe region shows the opposite trend. With the increase of the velocity ratio, the influence of the branch pipe structure on the main flow field gradually decreases. The rebound vortex accelerates the rupture of the vortex ring, and the higher injection speed of the branch pipe leads to an increase in the vortex strength and the range of mixing area, which enhances the mixing of the fluid and makes the temperature distribution of the flow field more uniform. Finally, through the power spectral density analysis of temperature fluctuations, it is not only found that the high-energy vortex ring falls off to the near-wall region, dominating the temperature fluctuation in this region, but also this type of T-junction greatly reduces the risk of thermal fatigue failure.

Microwave-induced Facile Synthesis of Highly Strained Three-membered Ring Compounds and Some of Their Reactions

Abstract:Compounds with three membered rings experience greater strain than those with other ring systems. In general, the synthesis of small ring compounds, particularly three-membered molecules, faces major challenges because of the severe strain in this system. Moreover, microwaveassisted method creates a higher temperature due to the heat and radiation of a reaction mixture more rapidly than conventional methods. This paper reports the successful synthesis of threemembered heterocyclic compounds via microwave-assisted reactions. Microwaves have assisted in making three-membered compounds while inducing high energy to the reaction mixtures. No reviews have reported the synthesis of these types of molecules either by microwave or conventional procedure. In addition, the reaction of a few three-membered ring compounds to other products through the ring rupture method is also included. On this basis of the chemistry (formation and breakage) of three-membered compounds described here, this report can be considered novel, timely, and highly significant. This review may help numerous researchers for further study in this field as the synthesis and cleavage of three-membered ring structures using a microwave is a challenging objective.

Fast Pyrolysis of Tea Waste under a Hydrogen-Rich Atmosphere: A Study on Nitrogen Evolution and Green Ammonia Production

Nitrogen-rich biomass pyrolysis has been explored as a green, distributed, and simple alternative for sustainable ammonia production at atmospheric pressure. In this paper, tea waste was selected as a promising feedstock, and H2 was employed as an enhancer to increase the yield of NH3. The nitrogen distribution among three-phase pyrolytic products affected by various temperatures and different atmospheres was compared and discussed. The evolution pathways for fuel–N during tea waste pyrolysis under a H2-rich atmosphere were concluded. Results indicated that the introduction of H2 was favorable for the increase of the gas–N yield but decreased the yields of char–N and tar–N. At lower temperatures, the bond cleavage of amide–N (N–A) in fuels was enhanced by H2, which then yielded more NH3–N through deamination. Subsequently, H2 improved the production of nitrile–N in tar, as well as NH3–N and HCN–N, by accelerating the secondary cracking of amine–N (tar–N) generated from the decomposition of amide–N. However, the formation of heterocyclic–N in tar through the polymerization of amine–N was restrained under a H2-rich atmosphere. Pyrolysis in the presence of H2 generated a large amount of H radicals. When the temperature continued to increase, sufficient H radicals impressively advanced the ring rupture (into HCN–N) and full hydrogenation (into NH3–N) of pyridinic–N/pyrrolic–N (N-6/N-5) in char. Meanwhile, H radicals also intensified the thermal cracking of nitrile–N and ring opening of heterocyclic–N to form more HCN–N and NH3–N. Overall, more nitrogen evolved into NH3–N and HCN–N during pyrolysis in a H2-rich atmosphere, especially at high temperatures. The highest NH3 yield of 43.33 wt % was achieved at 800 °C under a 25% H2 + 75% Ar atmosphere.

New fluorescein dyes with unusual properties: Tetra- and pentanitrofluoresceins

Among various fluorescein dyes, nitro derivatives are less studied. At the same time, these compounds have some unusual properties. This article reports on the behavior of new dyes of this series in solution. Two compounds, 2,4,5,7,4′- and 2,4,5,7,5′-pentanitrofluoresceins, were synthesized, and their molecular structures in the solid state and solution were characterized by X-ray diffraction analysis and NMR spectroscopy. Electronic spectroscopy in dimethyl sulfoxide, DMSO, proves that doubly charged anions of these compounds, R2–, exist in solution in the form of lactone structures, which is not characteristic of other fluorescein dyes. These lactones are yellow (λmax = 420–430 nm) due to the nitrophenolate absorption. On the contrary, singly charged anions are represented predominantly by fluorescent and intensely colored particles with molar absorptivities of (92–96)× 103 M−1cm−1 at λmax = 525 nm, while H2R molecular forms are colorless lactones. The dyes are relatively strong acids; pKa1 and pKa2 values ​​determined in DMSO do not exceed 5 units. It is important to note that in this solvent, as in other media, the pH range of the predominance of HR– monoanions is very narrow. The protolytic equilibrium state of 2,4,5,7-tetranitrofluorescein is similar. The product of the pyran ring rupture of the last-named dye was isolated and identified; this allowed to rationalize the color changes of the parent dye in aqueous solutions within a wide pH range. Of particular interest is the methyl ester of 2,4,5,7-tetranitrofluorescein. The esterification of the carboxyl group avoids lactonization. In contrast to the initial dye, this compound exists as a stable singly charged anion in a wide pH range in all solvents except nonpolar ones, and its fluorescence is very sensitive to the hydrogen bonding ability of the solvent.

Seeking Citius: Photochemical Access of Reactive Intermediates for Faster Bioorthogonal Reactions.

Fast bioorthogonal reactions are sought after because of their superior performance in labeling low-abundance biomolecules in native cellular environments. An attractive strategy to increase reaction kinetics is to access the reactive intermediates through photochemical activation. To this end, significant progress was made in the last few years in harnessing two highly reactive intermediates-nitrile imine and tetrazine-generated through photoinduced ring rupture and catalytic photooxidation, respectively. The efficient capture of these reactive intermediates by their cognate reaction partners has enabled bioorthogonal fluorescent labeling of biomolecules in live cells.

Application of Differential Magnetic Field Measurement (DMFM method) in winding fault detection of AC rotating machines as part of expert monitoring systems

Stator and rotor winding damages in rotating machines are result of electrical, mechanical, and thermal stress. Online magnetic field monitoring via permanently installed measuring coils inside air gap is a well-established methodology which enables winding fault detection. The paper deals with a new method for detection of stator and rotor winding inter-turn short circuits of synchronous machines and slip rings induction machines, as well as rupture of rotor bars and cage ring of induction machines. The method novelty is based on differential measurement of magnetic field by using two serial connected measuring coils. They are installed on the places (stator or rotor teeth) in the machine which have, by absolute value, equal magnetic vector potential. The distance between the measuring coils is n·tp, where tp is a pole pitch, and n = 1, 2, 3, 4,... is a multiple of the pole pitch. Measuring the coil-induced voltage enables us to detect stator and rotor winding faults, which means that measured voltage is approximately zero without fault and increases in the presence of fault. Analysis of the measuring signal allows us to detect and locate fault. With this new method it is possible with high sensitivity to determine winding fault, which enables more reliable fault detection. For example, in comparison with the motor current signature analysis method (the most widely used method for motor faults detection), this new method gives 200 times higher sensitivity to fault occurrence. Also, by using the DMFM method, faults can be detected in the time domain and there is no need for spectral or other complex signal analysis. This is very important because the measuring equipment used for machine fault detection can be simple and more economically acceptable. The DMFM method enables fault detection for even small machines with small expense in a very effective way. The only downside of the DMFM method is the fact that machine should be disassembled in order to install measuring coils. This problem is solved during the machine overhaul or during the manufacturing of the machine, when sensors can be easily implemented in the machine. For machines with large air gap, measuring coils can be installed without a machine disassembly. For the purpose of the method testing, numerous finite-element (FE) simulations on the 2- and 3-D machine models have been carried out to verify the method. Powerful numerical tools generate realistic results with properly selected starting and boundary conditions. By FEM models, actual machines with embedded measuring coils where created and simulated. The voltage induced inside the measuring coils is calculated for different machine states, load point and with and without a fault (broken rotor bar or inter-turn short circuit). Also, this method was experimentally validated via series of laboratory tests performed on the real electric machines specially designed for fault study (broken rotor bars, broken ring and inter-turn short circuits in a stator and rotor winding). Additionally, this method is applied on more than 20 real machines in industry. Due to the large amount of measured data, in this paper, it will be presented only one measurement performed on an induction motor on which we have detected one broken rotor bar. The thickness of the measuring coil designed in the printed circuit board technique is 0.3 mm. The number of turns is from 3 to 10. This new method and performed FEM calculations together with the experimental measurements improve fault detection portfolio knowledge that can be used in monitoring and diagnostics of rotating machines. Furthermore, this patent-pending method is already implemented in three innovative products placed on market (expert monitoring systems), so this method is fully confirmed in practice.

Three-Dimensional Biomechanical Finite Element Analysis of Lumbar Disc Herniation in Middle Aged and Elderly.

Lumbar intervertebral disc protrusion disease refers to the degeneration of intervertebral disc, rupture of fibrous ring, nucleus pulpous protrusion and stimulation or compression of nerve root. The import command in Mimics medical 3D reconstruction software was used to erase the irrelevant image data and obtain vertebral body images. The original 3D model of each vertebral body was built by 3D computing function. A three-dimensional finite element model was established to analyze the effect of different surgical methods on the mechanical distribution of the spine after disentomb. The stress distribution of the spine, intervertebral disc, and left and right articular cartilage at L4/L5 stage and the position shift of the fourth lumbar vertebra were analyzed under 7 working conditions of vertical, forward flexion, extension, left and right flexion, and left and right rotation. The results showed that the established model was effective, and the smaller the area of posterior laminar decompression was, the lesser the impact on spinal stability was. The PELD treatment of lumbar disc herniation had little impact on spinal biomechanics and could achieve good long-term biomechanical stability. Combining the clinical experiment method and finite element simulation, using the advantages of finite element software to optimize the design function can provide guidance for the design and improvement of medical devices and has important significance for the study of clinical mechanical properties and biomechanics.

Enhanced oxidative activation of chlorine dioxide by divalent manganese ion for efficient removal of PAHs in industrial soil

Chlorine dioxide (ClO2) takes effect as a promising chemical oxidant to remove polycyclic aromatic hydrocarbons (PAHs) from contaminated soil in situ. However, the conventional ClO2 degradation procedure is limited by its reaction selectivity to organic pollutants, as well as its low economic efficiency with huge dosage. Systematical study of activated ClO2 oxidation which is more efficient to remove PAHs in soil is still scarce. Herein, the impact of divalent manganese ion [Mn(Ⅱ)] on activating ClO2 to oxidize PAHs in real contaminated soil was currently studied, including the kinetics, degradation products, mechanisms, and biological toxicity. The results revealed that the PAHs removal rate constants (k1) had a quadratic relationship with Mn(II) concentrations (k1 = -0.005 × [Mn(Ⅱ)]2 + 0.0033 × [Mn(Ⅱ)] + 0.0222, R2 = 0.9084, [Mn(Ⅱ)] = 0 ∼ 5 mM), the best degradation performance was obtained when the molar ratio of Mn(II)/ClO2 was 1/20. Furthermore, the optimal initial ClO2 concentration of 2500 mg/L could satisfy the comprehensive considerations of efficiency and economy. At the pH range of 3 ∼ 11, the removal efficiency decreased with increasing pH. Four representative PAH congeners (anthracene, phenanthrene, pyrene, and fluoranthene) had been chlorine substituted and oxygenated, but benzene ring rupture was observed only in fluoranthene simultaneously. XPS spectra, EPR analysis, and quenching experiments indicated the mechanisms that HOCl and •OH were the principal active species in the oxidation reaction. The toxicity evaluation by earthworms Eisenia fetida resulted out that high toxic effect to organism still remained in remediated soil which should be paid attention to.

Initial decomposition step and bimolecular hydrogen transfer of 3, 3′-diamino-4, 4′-azoxyfurazan under high pressure and high temperature

3, 3′-diamino-4, 4′-azoxyfurazan (DAAF) is a promising energetic furazan compound. Few works about its chemical and physical properties under high pressure and high temperature are reported so far. Here the thermal decompositions of DAAF under high temperature and/or high pressure with neon gas or liquid water were studied using Raman spectra. Under high temperature and ambient pressure, the decomposition sequence of DAAF begins with the unimolecular homolysis of CNazoxy and further followed by the cleavage of NH in NH2 group and the rupture of furazan ring. Application of high pressure induces the different initial decomposition process accompanied the variation of the intermolecular and intramolecular interactions. The initial step of DAAF is the breakdown of NH at 473 K and 0.9 GPa, which facilitates the bimolecular hydrogen transfer from NH2 group to Oazoxy-N and finally induces the dissociation of the O from azoxy group. It results in the formation of DAAzF at 483 K when using neon as pressure transmitting medium. Moreover, big and fine rod-like DAAzF crystals are formed above 493 K at 0.8 GPa employing water as pressure transmitting medium. The existence of super high temperature water leads to the bimolecular hydrogen transfer and dissociation of Oazoxy from DAAF more easily for the interaction of Oazoxy…H and more DAAF crystals transformation into DAAzF.

Two sides of thermal stability of energetic liquid: Vaporization and decomposition of 3-methylfuroxan

Analysis of thermal behavior of liquids is often accompanied by vaporization. In an extreme case, the calorimetric (DSC) experiment reveals the only endothermic evaporation instead of the more valuable thermal decomposition. 3-Methylfuroxan (MMF) is an energetic monosubstituted 1,2,5-oxadiazole N-oxide that shows the above behavior. We investigate the sample mass and confinement effects and show that the pressure DSC allows observing thermal decomposition of target compound at 2.0 MPa. Advanced model-fitting kinetic analysis reveals two global stages, the first of which is a competition between the noncatalytic reaction and autocatalytic one, whereas the second global stage is a second-order reaction. Analysis of MMF thermolysis in solution in dibutyl phthalate shows the activation energy for noncatalytic reaction to be 145.4 ± 1.7 kJ mol−1. To resolve the gas decomposition products in experiments at 0.1 MPa pressure, where the evaporation is abundant, a gas chromatography–mass spectrometry coupled with thermal analyzer was used. Among the gases that are consistent with a furoxan ring rupture by CC and NO bonds (HNCO, CH3CN), we detect CH3COCN that retains CC bond. The formation of geminal cyanonitro compound in the course of thermolysis is proposed to explain the composition of the gas reaction products. Overall, with the range of thermal analysis tools (DSC, PDSC, GC–MS/TGA, thermokinetic modeling) we performed a detailed analysis of thermal transformations of unexplored simple monosubstituted furoxan. The applied methodological approaches could be transferred to other molecular liquids.