Analysis of Changes in the Opening Pressure of Marine Engine Injectors Based on Vibration Parameters Recorded at a Constant Torque Load.

This article deals with the problems related to the difficulties in the vibration diagnostics of modern marine engines. The focus was on the injection system, with a particular emphasis on injectors. An unusual approach to the implementation of research enabling the smooth regulation of the opening pressure of the mechanical injector during engine operation at a constant load was presented. This approach obtained repeatability of conditions for subsequent measurements, which is very difficult to achieve when using the classic approach that forces the injector to be disassembled after each test.

The Fatigue Wear Process of Rubber-Metal Shock Absorbers.

Rubber and rubber-metal vibration isolators are widely used vibration isolation systems in marine applications. For naval application, shock absorber mounting systems must fulfil two functions. The first one supports the suspended mass in the absence of waving or detonation while providing isolation from vibrations and shock impact. In the second case, during the machine operation, it reduces the force of movement to an acceptable value. Moreover, it returns the insulated mass to the position output without plastic deformation or residual buckling after removing shock stresses or harmonic vibrations. The environment in which marine vibration isolators are to be used strongly influences the selection of a shock absorber. The main environmental problem is the temperature range in marine power plants, which ranges from 20 °C to 55 °C. Temperature fluctuations may cause changes in the physical properties of typical vibration/shock insulators. Both rubbers and elastomers used for shock absorbers tend to stiffen, gain low-temperature damping, and soften and lose damping at elevated temperatures. Factors such as moisture, ozone and changes in atmospheric pressure are usually ignored in shipbuilding. The main environmental factors influencing the ageing of insulators are liquid saturated hydrocarbons, i.e., oils, fuels, coolants, etc., which may come into contact with the surface of the insulators. This work presents the results of the research carried out to determine the effect of overload and the impact of petroleum products on the materials of metal-rubber shock absorbers made of three different rubbers and one polyurethane mixture. For each of the materials, shock absorbers with three different degrees of hardness were tested.

Analysis of Exhaust Gas Content for Selected Biofuel-Powered Combustion Engines with Simultaneous Modification of Their Controllers.

The use of renewable resources for powering self-ignition engines in European Union countries involves a high demand for renewable energy which is not accompanied by the development of its production infrastructure. The application of biofuel in vehicle powering is supposed to provide reductions in greenhouse gas emissions and an increase in the share of renewable energy resources in the total energy consumption. The study includes the analyses of power unit exhaust components, such as oxygen, carbon monoxide, nitric oxides, carbonizers, carbon dioxide and a quantity of exhaust particles contained in exhaust gases. Tests using an exhaust gas analyzer and a vapor analyzer were conducted. Three high-pressure engines, characterized by direct fuel injection, were tested. The vehicle computer software adjustments included increasing the fuel dose and the air load. Mixtures of diesel oil and fatty acid methyl esters were used in the tests. Based on the results, a statistical analysis was performed and an assessment model was developed to understand the functioning of the research objects fueled with these mixtures, with simultaneous software changes in the vehicle computers. On the basis of the conducted analysis, it was found that only 30% of fatty acid methyl ester additives to diesel oil reduced the performance parameters of the drive units.

Intelligent Fault Diagnosis of Rotary Machinery by Convolutional Neural Network with Automatic Hyper-Parameters Tuning Using Bayesian Optimization.

Intelligent fault diagnosis can be related to applications of machine learning theories to machine fault diagnosis. Although there is a large number of successful examples, there is a gap in the optimization of the hyper-parameters of the machine learning model, which ultimately has a major impact on the performance of the model. Machine learning experts are required to configure a set of hyper-parameter values manually. This work presents a convolutional neural network based data-driven intelligent fault diagnosis technique for rotary machinery which uses model with optimized hyper-parameters and network structure. The proposed technique input raw three axes accelerometer signal as high definition 1-D data into deep learning layers with optimized hyper-parameters. Input is consisted of wide 12,800 × 1 × 3 vibration signal matrix. Model learning phase includes Bayesian optimization that optimizes hyper-parameters of the convolutional neural network. Finally, by using a Convolutional Neural Network (CNN) model with optimized hyper-parameters, classification in one of the 8 different machine states and 2 rotational speeds can be performed. This study accomplished the effective classification of different rotary machinery states in different rotational speeds using optimized convolutional artificial neural network for classification of raw three axis accelerometer signal input. Overall classification accuracy of 99.94% on evaluation set is obtained with the CNN model based on 19 layers. Additionally, more data are collected on the same machine with altered bearings to test the model for overfitting. Result of classification accuracy of 100% on second evaluation set has been achieved, proving the potential of using the proposed technique.

Fault Diagnosis of Rotary Machines Using Deep Convolutional Neural Network with Wide Three Axis Vibration Signal Input.

Fault diagnosis is considered as an essential task in rotary machinery as possibility of an early detection and diagnosis of the faulty condition can save both time and money. This work presents developed and novel technique for deep-learning-based data-driven fault diagnosis for rotary machinery. The proposed technique input raw three axes accelerometer signal as high definition 1D image into deep learning layers which automatically extract signal features, enabling high classification accuracy. Unlike the researches carried out by other researchers, accelerometer data matrix with dimensions 6400 × 1 × 3 is used as input for convolutional neural network training. Since convolutional neural networks can recognize patterns across input matrix, it is expected that wide input matrix containing vibration data should yield good classification performance. Using convolutional neural networks (CNN) trained model, classification in one of the four classes can be performed. Additionally, number of kernels of CNN is optimized using grid search, as preliminary studies show that alternating number of kernels impacts classification results. This study accomplished the effective classification of different rotary machinery states using convolutional artificial neural network for classification of raw three axis accelerometer signal input.

Screening test for extracranial carotid lesions' detection in patients of an outpatient vascular clinic.

Purpose The objective of the study was to evaluate the frequency and severity of atherosclerotic lesions in extracranial sections of carotid arteries and to determine the level of the correlation between these lesions and symptoms of cerebral ischemia. Secondly, to identify the most common risk factors of ischaemic stroke occurrence in population of patients of vascular outpatient clinic. Material and Methods Prospective study was conducted on a group of 1,000 people (217 women and 783 men), aged 50 to 86 years, the average age was 62 years (± 9.95). Results Atherosclerotic lesions of carotid arteries were observed in 670 examined people (67%). In 63 cases (6.3%) carotid artery occlusion was revealed. Patients with symptomatic carotid artery stenosis more frequently were addicted to cigarettes and suffered from hypertension in comparison to asymptomatic group. A statistically significant correlation between the TIA or ischemic stroke and smoking were noticed, as well as between TIA/ischemic stroke and hypertension Conclusions Among patients with atherosclerosis of peripheral arteries atherosclerotic lesions in the extracranial carotid sections occur with a high frequency. Statistically significant differences in the incidence and severity of atherosclerotic lesions in the carotid arteries were observed in this group. A statistically significant correlation was revealed between the prevalence and severity of atherosclerosis in the carotid arteries in symptomatic patients and smoking and hypertension. Performing screening in patients with atherosclerosis of the abdominal aorta and/or lower limb arteries may detect significant carotid artery stenosis, requiring surgical intervention.

Platinum(ii) complexes showing high cytotoxicity toward A2780 ovarian carcinoma cells.

2,6-Bis(thiazol-2-yl)pyridines functionalized with 9-anthryl (L1), 9-phenanthryl (L2), and 1-pyrenyl (L3) groups were used for the preparation of [Pt(Ln)Cl]CF3SO3 (1-3). The constitution of the Pt(ii) complexes was determined by 1H and 13C NMR spectroscopy, HR-MS spectrometry, elemental analysis and X-ray analysis (for (1)). The electrochemical and photophysical properties of [Pt(Ln)Cl]CF3SO3 were compared with the behaviour of the Pt(ii) complexes with aryl-substituted 2,2':6',2''-terpyridine ligands. What is noteworthy is that the coordination ability of dtpy toward the Pt(ii) centre was investigated for the first time. All complexes were tested in vitro by MTS assay on four tumor cell lines, A2780 (ovarian carcinoma), HTC116 (colon rectal carcinoma), MCF7 (breast adenocarcinoma), and PC3 (prostate carcinoma) and on normal primary fibroblasts. Compounds (1-3) showed a dose dependent antiproliferative effect in the A2780 cell line with (3) > (2) > (1) and this loss of A2780 cell viability was due to a combination of an apoptotic cell death mechanism via mitochondria and autophagic cell death. Exposure to IC50 concentration of (2) induced an increase in the number of apoptotic nuclei and a depolarization of the mitochondrial membrane which is consistent with the induction of apoptosis while exposure to IC50 concentration of (3) showed an increase in the apoptotic nuclei with a slight hyperpolarization of the mitochondrial membrane that might indicate an initial step of apoptosis induction. The complexes (2) and (3) induce an increase in the production of intracellular ROS which is associated with the trigger of the apoptotic pathways. The ROS production was augmented by the presence of oxidants and correlated with an increase of oxygen radicals. The IC50 of (2) and (3) (4.4 µM and 2.9 µM, respectively) was similar to the IC50 of cisplatin (3.4 µM) in the A2780 cell line, which together with their low cytotoxicity in normal fibroblasts, demonstrates their potential for further studies.

Endovascular treatment of iatrogenic arteriovenous fistula of the iliac vessel.

BACKGROUND: Iatrogenic vascular injuries, due to the particular nature of such pathology, are associated with high morbidity and mortality in the postoperative period. OBJECTIVES: The objective of this study was to present a case of non-classic approach to the therapy of iatrogenic arteriovenous fistula. MATERIAL AND METHODS: We present a case of a 17-year old female patient admitted to the Department of Vascular, General and Oncologic Surgery (Copernicus Memorial Hospital, Lódz, Poland) due to an iatrogenic injury to the common iliac vein and artery, following neurosurgical intervention on the spine. Two weeks prior to admission, the patient underwent surgery in the Neurosurgery Clinic for herniated nucleus pulposus and lumbar spine scoliosis. The imaging diagnostic revealed the presence of a pseudoaneurysm of the right common iliac artery and arteriovenous fistula between the right common iliac vessels. The patient was qualified for endovascular treatment. Two self-expanding covered stents were successfully deployed. The clinical and radiological outcome of the procedure was good. The postoperative period was uneventful. The patient was discharged home on the 3rd postoperative day. RESULTS: The control examinations (directly after the procedure and 6, 12, 24 and 32 months thereafter) revealed full patency of the iliac vessels, as well as no recurrence of arteriovenous fistula, nor a pseudoaneurysm of the right common iliac artery. No symptoms of either chronic limb ischaemia or venous insufficiency were observed. CONCLUSIONS: Iatrogenic vessel injury, being a complication of neurosurgical and orthopedic surgeries, may be overlooked and remain undetected both in intraand postoperative period. Modern imaging techniques allow for an adequate diagnosis of the injury and planning the treatment of arteriovenous fistula. The endovascular procedures are the method of choice in patients with arteriovenous fistulas of iliac vessels, alternative to open surgery.

Luminescent-Substituted Fluoranthenes-Synthesis, Structure, Electrochemistry, and Optical Properties.

Six novel fluoranthene derivatives, namely, three terminally substituted and three bis(fluoranthene) units with fluorene, bithiophene, and carbazole spacers, were obtained through [2+2+2] cycloaddition and characterized completely. Based on the conducted studies, the obtained derivatives can be classified as donor-acceptor (D-A) and acceptor-donor-acceptor (A-D-A) systems, in which the fluoranthene unit acts as an electron-withdrawing unit. The optical results revealed that novel fluoranthene derivatives absorb light in the range λ=236-417 nm, which originates from a π→π* transition within the conjugated system. The compounds exhibit fluorescence that range from deep blue to green, which mainly arises from intramolecular charge transfer (ICT) states. High Stoke shifts and high quantum yields in solution (ϕ=0.22-0.57) and in the solid state (ϕ=0.18-0.44) have been observed for fluoranthene derivatives. All the derivatives display multistep oxidation processes at low potentials. The electronic structure of the presented compounds is additionally supported by time-dependent DFT computations.

Gender-related risk factors for perioperative stroke after carotid endarterectomy in symptomatic patients.

BACKGROUND: Carotid endarterectomy (CEA) is a surgical procedure used in ischemic brain stroke prevention in patients with symptomatic and asymptomatic severe carotid artery stenosis. OBJECTIVES: This study compares perioperative stroke or death rate after carotid endarterectomy (CEA) in male and female patients, and determines risk factors for perioperative incidents in women and men. MATERIAL AND METHODS: The outcome of surgical treatment of 269 consecutive symptomatic patients (181 men and 88 women) treated from January 2004 to August 2008 in the Department of Vascular, General and Oncologic Surgery was analyzed. RESULTS: Perioperative stroke-death rate (within 30 days after the surgery) in women was 6.8% (6/88) and 3.3% (6/181) in men (p > 0.05). In the female group, none of the analyzed risk factors were associated with a higher risk of periprocedural incident, while in men, only hypercholesterolemia was a significant predictor of perioperative stroke (TC > 240 vs 240 vs 200-240: OR = 6.59; 95% CI: 1.12-38.97; p = 0.0375). CONCLUSIONS: In men, hypercholesterolemia significantly increased the risk of perioperative stroke or death, while in females, none of the analyzed factors were determined as the predictors of the incident. The fact that plaque type VI by AHA was significantly more frequent in women and men more frequently were suffering from ischemic heart disease and peripheral artery occlusive disease appeared not to influence the outcome of CEA.

NCN-Coordinating Ligands based on Pyrene Structure with Potential Application in Organic Electronics.

Five novel derivatives of pyrene, substituted at positions 1,3,6,8 with 4-(2,2-dimethylpropyloxy)pyridine (P1), 4-decyloxypyridine (P2), 4-pentylpyridine (P3), 1-decyl-1,2,3-triazole (P4), and 1-benzyl-1,2,3-triazole (P5), are obtained through a Suzuki-Miyaura cross-coupling reaction or CuI -catalyzed 1,3-dipolar cycloaddition reaction, respectively, and characterized thoroughly. TGA measurements reveal the high thermal stability of the compounds. Pyrene derivatives P1-P5 all show photoluminescence (PL) quantum yields (Φ) of approximately 75 % in solution. Solid-state photo- and electroluminescence characteristics of selected compounds as organic light-emitting diodes are tested. In the guest-host configuration, two matrixes, that is, poly(N-vinylcarbazole) (PVK) and a binary matrix consisting of PVK and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) (50:50 wt %), are applied. The diodes show red, green, or blue electroluminescence, depending on both the compound chemical structure and the actual device architecture. In addition, theoretical studies (DFT and TD-DFT) provide a deeper understanding of the experimental results.

Resilience and Alternative Stable States of Tropical Forest Landscapes under Shifting Cultivation Regimes.

Shifting cultivation is a traditional agricultural practice in most tropical regions of the world and has the potential to provide for human livelihoods while hosting substantial biodiversity. Little is known about the resilience of shifting cultivation to increasing agricultural demands on the landscape or to unexpected disturbances. To investigate these issues, we develop a simple social-ecological model and implement it with literature-derived ecological parameters for six shifting cultivation landscapes from three continents. Analyzing the model with the tools of dynamical systems analysis, we show that such landscapes exhibit two stable states, one characterized by high forest cover and agricultural productivity, and another with much lower values of these traits. For some combinations of agricultural pressure and ecological parameters both of these states can potentially exist, and the actual state of the forest depends critically on its historic state. In many cases, the landscapes' 'ecological resilience', or amount of forest that could be destroyed without shifting out of the forested stability domain, declined substantially at lower levels of agricultural pressure than would lead to maximum productivity. A measure of 'engineering resilience', the recovery time from standardized disturbances, was independent of ecological resilience. These findings suggest that maximization of short-term agricultural output may have counterproductive impacts on the long-term productivity of shifting cultivation landscapes and the persistence of forested areas.

Morphometric parameters of extraocular rectus muscles evaluated by dynamic-multipositional magnetic resonance.

PURPOSE: To establish normal values of morphologic parameters of extraocular rectus muscles visualized in different gaze positions by means of an accessible method of dynamic-multipositional magnetic resonance imaging (dmMRI). METHODS: Twenty eyes of 10 healthy, orthotropic subjects were examined. A 1.5T scanner (Avanto) with standard head coil was used. The protocol of dmMRI included 6 gaze positions in 10° intervals in which 13-second, orbital, T2 sequences were performed in quasi-coronal plane. The measurements of extraocular rectus muscles shape, sectional area, and volume were obtained with use of ImageJ 1.38x (NIH) software. RESULTS: Relative change in cross-sectional area between position of rest and gaze of action of each muscle appears to be significant just in the medial and posterior parts of their belly. The maximal cross-section area increases significantly when the muscle contracts (21% to 32% depending on the muscle). The superior rectus must be assessed along with levator palpebrae as the distinction between their bellies is difficult. Relative change in partial muscle volume on contraction ranged from 12.3% to 21.6% depending on the muscle. Muscle contraction results in more circular shape of its belly while relaxation is more of an ellipse. CONCLUSIONS: Dynamic-multipositional MRI performed in the proposed manner is an accessible and repeatable method for visualization of extraocular rectus muscles. Assessment of morphometric parameters such as muscle shape, maximal cross-section area, and partial muscle volume is easy with digital imaging software.

Multifaceted strategy for the synthesis of diverse 2,2'-bithiophene derivatives.

New catalytically or high pressure activated reactions and routes, including coupling, double bond migration in allylic systems, and various types of cycloaddition and dihydroamination have been used for the synthesis of novel bithiophene derivatives. Thanks to the abovementioned reactions and routes combined with non-catalytic ones, new acetylene, butadiyne, isoxazole, 1,2,3-triazole, pyrrole, benzene, and fluoranthene derivatives with one, two or six bithiophenyl moieties have been obtained. Basic sources of crucial substrates which include bithiophene motif for catalytic reactions were 2,2'-bithiophene, gaseous acetylene and 1,3-butadiyne.

Acute brain ischemia as a complication of the Ehlers-Danlos syndrome, the case series.

Vascular type of Ehlers-Danlos syndrome involves many severe complications leading not only to organ-specific symptoms but often ends in a sudden death. The aim of this paper was to present a diagnostic possibilities and its efficiency rate in patients with vascular complications of Ehlers-Danlos syndrome who suffered from artery dissection resulting in acute brain or limb ischemia. We analysed three patients with diagnosed Ehlers-Danlos syndrome who were referred to radiology department for diagnostic imaging of affected vascular beds, each experienced brain ischemia. The paper also aims at offering some general recommendations for patients suffering from possible complications of type IV Ehlers-Danlos syndrome basing on our own experience and available literature data.

Signal intensity and T2 time of extraocular muscles in assessment of their physiological status in MR imaging in healthy subjects.

BACKGROUND: Lack of standardised orbital MR protocols leads to a situation, when each institution/centre may arbitrarily choose sequence parameters. Therefore, the results obtained and published by the authors may not be compared freely, and what is most important may not be considered fully reliable. Signal intensity (IS) and T2 time (T2) are important parameters in estimation of inflammatory processes of extraocular muscles in the clinical practice. The aim of this study was to determine the reference values (i.e. cut-off values) for absolute signal intensity and T2 relaxation time in healthy subjects, their relativised values to white matter (WM) and temporal muscles (TM) and to evaluate the correlation between those parameters. MATERIAL/METHODS: The orbital examination was performed in healthy volunteers according to the protocol prepared in the Radiology-Imaging Diagnostic Department of the Medical University of Lodz for patients with suspected/diagnosed thyroid orbitopathy. Using two of the standard sequences IS and T2 time were calculated for the muscles and two relativisation tissues in realtion to WM and TM. Subsequently cut-off values for healthy volunteers were calculated. RESULTS: The differences between muscles for IS, IS MAX, IS/TM, IS/WM, IS MAX/TM, IS MAX/WM and T2 MAX/WM were not statistically significant. Therefore one cut-off value of these parameters for all the rectus muscles was calculated. T2-relaxation time and T2 relativised to white matter had to be calculated separately for each muscle. CONCLUSIONS: No statistical correlation was found between IS and T2-time for extraocular muscles in healthy volunteers. We calculated the reference ranges (cut-off values) for absolute IS and T2-time values and relativised parameters. In the clinical practice the objectification of IS and T2-time values should be done to WM, than to IS or T2 of the temporal muscle. The T2 MAX/WM seems to have the highest clinical utility for the assessment of the pathophysiological status of extraocular muscles.

Magnetic Resonance evaluation of disease activity in Graves' ophthalmopathy: T2-time and signal intensity of extraocular muscles.

BACKGROUND: It is accepted that T2-weighted imaging can demonstrate the extent of an inflammatory process in Graves' ophthalmopathy (GO). This aim of this study was a comparative evaluation of the most commonly used indicators of extraocular muscle pathophysiology, i.e. signal intensity (SI) and T2-time (T2-t) in correlation with muscle volume (MV), and to determine the need to make the above indicators objective with regards to clinical practice. MATERIAL/METHODS: MRI examinations in a 1.5 T scanner of 40 orbits formed the study group. Quantitative assessment of the muscles was carried out using a numerical segmentation imaging technique (NSI). SI and T2-t were measured for each muscle. A standardization algorithm was applied based on T2-t and IS from the ipsilateral white matter of the frontal lobes. RESULTS: The correlation between T2-t and MV for the medial rectus and inferior rectus muscles (IRM) was at a comparatively high level (R: 0.49 and 0.47), with a value as high as R=0.58 for the superior rectus muscle. Correlation between SI and volume for these muscles was found to be at R-levels of 0.37, 0.48, and 0.46. Correction of the T2-t and SI values with use of a standardization algorithm in most cases did not change the above correlations, except for IRM. CONCLUSIONS: The parameter with the higher correlation to the symptoms of GO is T2 The value of SI as an indicator of disease intensity in GO that can be used without the use of multiple echo sequences was confirmed. It is necessary to make the above parameters objective relative to white matter when calculating IS for the inferior rectus muscle.