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Background Albuminuria has been classically considered a marker of kidney damage progression in diabetic patients and it is routinely assessed to monitor kidney function. However, the role of a mild GFR reduction on the development of stage ≥3 CKD has been less explored in type 1 diabetes mellitus (T1DM) patients. Aim of the present study was to evaluate the prognostic role of kidney disease measures, namely albuminuria and reduced GFR, on the development of stage ≥3 CKD in a large cohort of patients affected by T1DM. Methods A total of 4284 patients affected by T1DM followed-up at 76 diabetes centers participating to the Italian Association of Clinical Diabetologists (Associazione Medici Diabetologi, AMD) initiative constitutes the study population. Urinary albumin excretion (ACR) and estimated GFR (eGFR) were retrieved and analyzed. The incidence of stage ≥3 CKD (eGFR 30% from baseline was evaluated. Results The mean estimated GFR was 98 ± 17 mL/min/1.73m2 and the proportion of patients with albuminuria was 15.3% (n = 654) at baseline. About 8% (n = 337) of patients developed one of the two renal endpoints during the 4-year follow-up period. Age, albuminuria (micro or macro) and baseline eGFR 90 ml/min/1.73m2 and normoalbuminuria, those with albuminuria at baseline had a 1.69 greater risk of reaching stage 3 CKD, while patients with mild eGFR reduction (i.e. eGFR between 90 and 60 mL/min/1.73 m2) show a 3.81 greater risk that rose to 8.24 for those patients with albuminuria and mild eGFR reduction at baseline. Conclusions Albuminuria and eGFR reduction represent independent risk factors for incident stage ≥3 CKD in T1DM patients. The simultaneous occurrence of reduced eGFR and albuminuria have a synergistic effect on renal function worsening. Electronic supplementary material The online version of this article (10.1186/s12882-018-1136-6) contains supplementary material, which is available to authorized users.

Summary Background & aims Alpha-lipoic acid (ALA)-containing dietary supplements are widely used in clinical practice, although their safety assessment is under-investigated. We characterize the safety profile of ALA-containing products by analysing spontaneous reports of suspected adverse reactions (ARs). Methods Suspected ARs to ALA-containing products were extracted from the Italian Phytovigilance System (IPS), and scrutinized in terms of seriousness and causality (through WHO UMC system), with a specific focus on important (IMEs) and designated medical events (DMEs). To characterize the reporting profile from an international perspective, the WHO-VigiBase was also queried. Results From March 2002 to February 2020, out of 2147 total reports, 116 reports concerning 212 ARs to ALA-containing products were collected. Women were involved in 68.1% of cases. Skin (44.9%) and gastrointestinal disorders (10.8%) were the most frequently represented ARs. Causality assessment resulted as definite (15), probable (35), possible (24), unlikely (5), and unclassifiable (37). In 70% of cases, events occurred within 30 days of ALA use. Forty-five reports were serious (38.8%), being insulin autoimmune syndrome the most frequently reported (N = 10). IMEs were recorded in 20 cases, including four DMEs (3 angioedema and one anaphylactic shock). Similar distribution emerged from the 5641 reports in the WHO-VigiBase. Conclusions The remarkable reporting of unpredictable skin, immune and hepatic ARs, coupled with seriousness, strong causality and early onset, calls for a) careful risk-benefit assessment of ALA-containing products by regulators; b) awareness and monitoring by clinicians and c) continuous vigilance of their safety profile through valuable spontaneous reporting systems such as IPS.

This paper provides a deep insight into fault location on long Submarine Power Cables. Several field results on submarine power cable faults are provided. For land cables the main focus is on the electrical and thermal design of cable insulation and on the electro-thermal and thermo-mechanical design of cable accessories, in order to grant sufficient endurance performances and reliability to the whole cable systems (Mazzanti, G., Marzinotto, M., Extruded cables for high-voltage direct current transmission: advances in research and development. New York, Wiley-Blackwell, 2013). In submarine cables more issues arise, some related to the harsh laying environment, some others—even more troublesome—associated with man-made activities. Indeed, on the one hand submarine power cables are subject to strong mechanical stresses during the laying operations and critical service conditions in their working ambience. On the other hand, submarine cables are continuously exposed in all water depth to random mechanical damages caused by fishing gears, anchors and natural hazards (Bawart, M., Marzinotto, M., in Insulated Conductors Committee ICC/IEEE-PES, C11D submarine cables, St. Petersburg, FL, November, 2012; CIGRE, Third-party damage to underground and submarine cables, Brochure 398, WG B1.21, December, 2009). The longer the expected life and the longer the path of the submarine cable link, the higher is the probability of facing one or more faults due to human activities. Based on surveys about submarine cable failure data recorded worldwide over long periods, it can be concluded that the probability of experiencing at least one fault during lifetime is close to certainty for long submarine links. Statistically most damages to submarine cables are caused by human activities; only a low percentage is caused by natural hazards. Based on growing energy demand and dependency on offshore produced renewable energy, submarine power cables become essential for reliable electric power supply and often can be classified as critical infrastructure (International Cable Protection Committee—ICPC, About submarine power cables, 2011, www.iscpc.org ). Repair of damaged submarine power cables requires specialized ships as well as experts to recover the cable from the sea bed and replace the faulty cable section. Another critical aspect associated with long submarine cables is that, whenever a fault occurs, a fairly long time is spent for repair. For this reason, fast and efficient fault detection is essential in order to reduce the overall outage time as much as possible. All these aspects are discussed in this paper. The best practice commonly employed for classifying submarine power cable fault types are included in the paper, together with the results of measurements carried out in the field. The paper points out that fault location on submarine power cables differs by much from classical cable fault location on buried land cables as to both conditions and measuring methods, thereby illustrating the most efficient cable fault location methods. Some field results on submarine power cable faults are provided, measured on AC submarine cables as well as on HVDC submarine links. A unique case study of fault location on longest HVDC Submarine Link will illustrate TDR based measurements on cable lengths above 400 km. The case studies further focus on TDR diagram analysis in order to explain how to identify cable joints. The results prove that the overall outage time for repair activities can drop significantly if the fault location system is peculiarly designed for detecting faults in very long submarine cables with a good measuring accuracy. The hazards for operators and instruments connected to the huge amount of electrical energy that may be stored in very long links are also tackled in the paper, thereby addressing the particular safety issues involved by extra-long submarine cables.

α-Hexylcinnamaldehyde (HCA) and p-tert-butyl-alpha-methylhydrocinnamic aldehyde (BMHCA) are synthetic aldehydes, characterized by a typical floral scent, which makes them suitable to be used as fragrances in personal care (perfumes, creams, shampoos, etc.) and household products, and as flavouring additives in food and pharmaceutical industry. The aldehydic structure suggests the need for a safety assessment for these compounds. Here, HCA and BMHCA were evaluated for their potential genotoxic risk, both at gene level (frameshift or base-substitution mutations) by the bacterial reverse mutation assay (Ames test), and at chromosomal level (clastogenicity and aneuploidy) by the micronucleus test. In order to evaluate a primary and repairable DNA damage, the comet assay has been also included. In spite of their potential hazardous chemical structure, a lack of mutagenicity was observed for both compounds in all bacterial strains tested, also in presence of the exogenous metabolic activator, showing that no genotoxic derivatives were produced by CYP450-mediated biotransformations. Neither genotoxicity at chromosomal level (i.e. clastogenicity or aneuploidy) nor single-strand breaks were observed. These findings will be useful in further assessing the safety of HCA and BMHCA as either flavour or fragrance chemicals.

The increased diffusion of power-electronic drives in electrical plants and networks is worsening the quality of energy supply, particularly voltage-waveform distortion. The harmonic content of voltage and current has been shown to contribute to accelerated degradation of insulation systems and, thus, to premature failure of electrical components. This paper focuses on life performance of insulation systems (capacitors and induction motors) supplied with nonsinusoidal voltage. The results of life tests under sinusoidal and distorted voltage waveforms are presented and discussed on the basis of the Voltage Endurance Coefficient of the life lines, considering various reference factors, such as voltage peak, peak-to-peak and rms. In particular, the distorted waveforms are obtained considering either low-frequency harmonics (typically present on supply ac lines) or high-frequency harmonics (affecting insulation systems of power-electronics controlled loads). It is shown that the main acceleration factor should be associated to the increase of voltage peak and supply-waveform frequency, while waveshape and rms value can play a minor role.

The review of materials, design and testing of joints for HVDC extruded cable systems provided in previous Part 1 paved the way to this Part 2 position paper by the DEIS HVDC Cable Systems Technical Committee, whose aim is to remedy the scarcity of existing standardized tests on joints. After a sound analysis, here routine tests are identified as the first practical target for the onset of new testing procedures, AC-PD measurements as the readily-available measurement from manufacturers' experience for quality control of joints during routine tests and VHF/UHF wireless sensors as the best tool for such measurements in the noisy environment of factories. Thereby, a novel protocol for PD measurement using AC voltages and VHF/UHF electromagnetic sensors, for quality control during routine tests on HVDC extruded joints, is proposed. The insulation of HVDC extruded cable system joints. Part 2: Proposal of a new AC voltage PD measurement protocol for quality control during routine tests © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

High voltage direct current (HVDC) cable systems with extruded insulation are becoming increasingly attractive versus the traditional mass impregnated non-draining (MIND) HVDC cable systems [1]. Voltage and power ratings of HVDC extruded cable systems commercially available - after being qualified according to CIGRE Technical Brochure (TB) 496 [2] - are exceeding 500 to 600 kV and 1 GW, respectively [3]-[6]. Of course, HVDC extruded cable systems still have issues.

In a previous paper (Part 1) the authors have performed the simulative evaluation of the life lost by HVDC extruded cables subjected to long TOVs occurring in VSC HVDC cable systems. The conclusions were that it cannot be completely ruled out that the field levels and the duration of such TOVs are a potential threat to certain cable designs, and tests other than Load Cycling Type Tests after CIGR Technical Brochure 496 could assess quantitatively the potential threat associated with long TOVs. For these reasons, in this Part 2 superimposed switching impulses applied during Type Tests after TB 496 are analyzed in order to check if such impulses might be equivalent to long TOVs as for their electro-thermal stress effects on extruded insulation. The analysis is similar to that carried out for long TOVs in Part 1, i.e. it consists of: calculating the electric field during superimposed switching impulses; comparing it with the field during long TOVs; calculating with Miner's law of cumulated damage the life lost during superimposed switching impulses and comparing it with the loss of life during TOVs. A brief literature survey of potential high field effects during long TOVs is also reported.

Extensive simulations have been carried out of transient voltages superimposed onto the DC voltage of HVDC cable transmission systems. With the advent of VSC HVDC cable systems, attention has turned to long Temporary Overvoltages in such systems. Preliminary experiments on the possible adverse effects of these long TOVs on the insulation of VSC HVDC cables have started, but no simulation models for estimating their effect on cable life and reliability have been developed yet. This investigation fills this gap by performing the simulative evaluation of the life lost by HVDC extruded cables subjected to long TOVs (Part 1) and switching impulses applied during Type Tests (Part 2), so as to compare the severity of these two transient voltages superimposed onto the DC voltage of HVDC extruded cables. This Part 1-paper is focused on estimating the severity of TOVs on extruded cable insulation by: calculating the electric field during the TOV; comparing it with the field during Type Test load cycles; using Miner's law of cumulated damage to calculate the life lost during the TOV, thereby also locating the most severely stressed point of insulation. In Part 2-paper, a similar evaluation for switching impulses and an overall comparison are performed

Pole-to-ground faults in HVDC transmission systems with Voltage Source Converters may cause Long Temporary Over-Voltages on the healthy pole of the configuration. This work aims at a preliminary experimental evaluation of the effect caused by the repetitive application of such Long TOVs on the XLPE insulation for HVDC cables. This paper also studies the changes in the dielectric relaxation properties, with their proposed mechanism, of 0.15 mm-thick XLPE sheets after being subjected to different levels of electrical aging due to TOVs.

Interface charge accumulation, leading to unpredictable insulation breakdown, restricts the development and industrialisation of high voltage direct current (HVDC) power equipment. Understanding the mechanism of interface charge transport and interface charge triggered dielectric breakdown is, therefore, of particularly high interest and vital importance. For example, the surface charging of aircraft in space brings damage to board electronic instruments as well as interference to sensing systems. Moreover, the randomly distributed charge clusters on the spacer surface, as shown in the cover page of this Special Issue, is considered as a potential threat to the surface flashover, while the accumulation of space charge within the insulating material poses a threat to the reliability of DC power cables. However, currently we still know very little about the development of charge dynamics in different interfaces, and the related breakdown mechanism of dielectrics induced by charge accumulation is also not very clear. This Special Issue brings together recent studies of charging phenomena for dielectric interfaces including vacuum-solid interface, gas-solid interface, and solid-solid interface. Nine highquality papers are accepted for publication in this Special Issue: six papers focusing on gas-solid interface (including one review paper), two review papers focusing on vacuum-solid interface, and one paper focusing on solid-solid interface. A brief discussion of each paper is presented as follows.

This paper investigates the effect of temperature and stress coefficients of electrical conductivity of the insulation material on the life and reliability of HVDC extruded cables subjected to type test load cycles according to CIGRE Technical Brochure 496. The investigation is done by refining a procedure for the estimation of cable insulation life and reliability in the presence of load cycles, developed and implemented in a previous stage of this research, but applied so far to prequalification test load cycles only. Electric field is calculated using both the rigorous approach based on Maxwell's equations for transient electric field computation (exact method) and the closed-form steady-state Eoll's formula often employed in the preliminary design of DC cable insulation (approximated method). This enables also to assess the accuracy of the overall approximation involved by Eoll's formula in the case of type test conditions.

HVDC transmission is booming worldwide. Despite electrode systems are one of the frontiers of DC technology, being a key component of HVDC links, in the experience of the Authors many aspects of their manufacturing, design and operations are less known among the HVDC community with respect to other components, like cables and converters. Aiming at filling this gap, this paper is a survey on ground/sea return with electrode systems for HVDC links, particularly focused on the preliminary design. The configurations of HVDC systems (monopolar, homopolar, bipolar) are recalled first, highlighting the advantages of ground/sea return. Then, ground electrodes are treated, illustrating the basic parameters and geometrical arrangements for the design of ground electrodes. Later, shore and sea electrodes are illustrated. Considerations relevant to ground current close the paper.

The improved features of AC/DC converters, the need to enhance cross-country interconnections, the will to make massive remote renewable energy sources available, and the fear of populations about overhead lines have fostered HVDC cable transmission all over the world, leading in the last two decades to an exponential increase of commissioned HVDC cable projects, particularly of the extruded insulation type. Comprehensive surveys of the issues to be faced by HVDC extruded cable systems appeared in the literature some years ago, but they are not so up-to-date, as HVDC extruded cable technology is developing fast. Therefore, the contribution this paper aims at giving is a systematic, comprehensive and updated summary of the main present and future issues and challenges that HVDC cable systems have to face to further improve their performance and competitiveness, so as to meet the growing quest for clean and available energy worldwide. The topics covered in this review–treated in alphabetical order for the reader’s convenience–are accessories, higher voltage and power, laying environment (submarine and underground cables), modeling, multiterminal HVDC, operation and diagnostics, recyclable insulation, space charge behavior, testing, thermal stability, transient voltages.

HVDC cables connected to Current Source Converters are subjected to polarity reversal when the HVDC intertie changes the power flow. Mass Impregnated Non-Draining cables had been using since the dawn of HVDC transmission with Current Source Converters and over the years they have shown their own ability to withstand the overstressing electric field values that arise during a polarity reversal. Cable manufacturers give restrictions on the number of polarity reversal that a cable can sustain and furthermore they give procedures to pursue in order to preserve cable life under such conditions. A phenomenological ageing model under fast polarity reversal is illustrated in this paper giving some information about its parameters. Besides, a space charge measurement test method to be applied during laboratory tests on full sized cables is illustrated in line with the IEEE 1732 standard. Aim of this paper is to merge the two approaches since the outcomes of space charge measurements on full sized cables can help in the parameters inference of the polarity reversal ageing model.

Cable joints reliability is crucial for a smart power system. A high rate of cable failure in underground cable power networks is due to the cable joints. The causes of cable joint failure can be identified through in-field monitoring of their electrical and environmental parameters. This paper is about modular units designed to measure current, pressure, temperature and humidity. These units have been installed in Palermo (south of Italy) at e-distribuzione MV network. First results of the measurement campaign are shown as well.

Pulmonary arterial hypertension is a severe disease with a complex pathogenesis, for which combination therapy is an attractive option.This study aimed to assess the impact of sequential combination therapy on both short-term responses and long-term outcomes in a real-world setting.Patients with idiopathic/heritable pulmonary arterial hypertension, or pulmonary arterial hypertension associated with congenital heart disease or connective tissue disease and who were not meeting treatment goals on either first-line bosentan or sildenafil monotherapy, were given additional sildenafil or bosentan and assessed after 3–4 months. Double combination therapy significantly improved clinical and haemodynamic parameters, independent of aetiology or the order of drug administration. Significant improvements in functional class were observed in patients with idiopathic/heritable pulmonary arterial hypertension. The 1-, 3- and 5-year overall survival estimates were 91%, 69% and 59%, respectively. Patients with pulmonary arterial hypertension associated with connective tissue disease had significantly poorer survival rates compared to other aetiologies (pThe favourable short-term haemodynamic results and good survival rates, observed in patients receiving both bosentan and sildenafil, supports the use of sequential combination therapy in patients failing on monotherapy in a real-world setting.

In this paper, a new procedure is presented for life estimation of HVDC cables subjected to the time-varying electrothermal stress associated with load cycles and voltage. The electric-field inversion phenomenon in the insulation of dc cables is accounted for by updating the field profile as the temperature profile changes with the load. The thermal transients due to load cycles are modeled via the CIGRÉ transient thermal network adapted to dc cables. The life fractions lost during each cycle because of the cyclic variation of the electrothermal stress are computed via an adequate electrothermal life model for the insulation of HVDC cables. The Weibull hypothesis is made for relating cable life to failure probability. The procedure is applied to the load cycles of the prequalification test for HVDC extruded cables after CIGRÉ Technical Brochure 496 that does not consider the effect of thermal and synergistic electrothermal aging. It is thus shown that this test might be less severe than it should be. © 1986-2012 IEEE.

This is the second part of an investigation aimed at providing a thorough technical comparison between traditional and alternative overhead power transmission lines based on the loadability characteristics. The previous Part I has outlined and applied the fundamentals of the loadability analysis to three comparable single-circuit lines. In the present Part II, the analysis is broadened to three comparable double-circuit lines: traditional three-phase ac double-circuit lines (assumed as the reference system for the comparison), bipolar HVDC lines and non-conventional combined ac-dc lines. As in Part I, the loadability analysis takes into account thermal limits, voltage drop, power losses and – when feasible – steady-state and transient stability. Part II also performs an overall comparison among the different systems in single-circuit and double-circuit configuration to draw final conclusions.

This paper proposes a simple innovative formula for the calculation of the magnetic field generated by a single and a double circuit twisted three-phase power cable line. The formula results a good approximation of the rigorous analytical one and at the same time is much more accurate than the approximated formula found in literature, as demonstrated by some cases of a twisted three-phase power cable used for power distribution at the medium voltage level. The effectiveness of this simple innovative formula is also examined in the case of a double-circuit twisted three-phase power cable line following the’ worst case’ approach and concluding at proposing an approximate expression for the total magnetic field generated by both twisted three-phase power cables.

Renewable energy sources provide power in a form not directly deliverable to the grid, thereby requiring power electronic converters. Parallel inverters are generally used to achieve high reliability and reduce inverter rating. In this paper the inherent limitations of conventional droop control method for low voltage parallel inverters with mainly resistive tie line are shown, and multi-loop control strategy is proposed. Such strategy uses proportional plus multi-resonant controllers to achieve high quality of the voltage through harmonic distortion rejection. The design procedure of this controller is investigated thoroughly and it is shown that both controller resonant gain and bandwidth affect the stability of the system. Also a new configuration for virtual resistive impedance loop is proposed to improve the accuracy of both linear and non-linear load sharing without degrading voltage quality. Simulation results with two 4-kVA inverters are provided, showing proper stability margin, having sinusoidal voltage in the presence of nonlinear load, power sharing with a good accuracy and proper dynamic. Furthermore, some highlights on system reliability, and its possible improvements by proper redundancy, are briefly illustrated at the end of the paper.

This paper illustrates the development and the experimental validation of a life model for LEDs subjected to thermal stress. The basis is the Arrhenius model for electrical insulation. The parameters of the life model are derived from accelerated life tests carried out on five samples of LEDs emitting light of different colours, namely red, green and blue. Each sample was subjected to a given value of constant temperature until the failure of all specimens. The diagnostic property for denoting failure is the residual light emitted by the LEDs under rated forward current, monitored continuously by a diagnostic system controlled via LabView. This study is the first step of an investigation whose ultimate goal is characterizing the endurance of LEDs having different colours to the stresses they face on duty, among which temperature is often one of the most challenging.

The estimation of wind speed extreme values is a topic assuming increasing importance in wind energy studies. Two different methods are compared here for that purpose, in view of safety applications. The first model is a parametric one, based upon a classical extreme value model, such as the Gum-bel or the Inverse Weibull distribution. The alternative model is a "non parametric" one, based upon a stochastic characterization of the wind speed by means of a Poisson distribution. For both methods, estimates are carried out by means of Bayes estimation approach. The two approaches are compared in terms of robustness of the estimates of a proper safety index, with respect to departures from the assumed wind speed model. A large set of simulations results are discussed, as a first step towards a deeper insight to wind speed estimation methods, taking into account model uncertainty.

Prediction of extreme values of wind speed is a key issue for both wind energy and wind tower safety assessment. The paper proposes a new method for such estimation, in the framework of safety assessment under extreme wind speed, based upon an adequate probabilistic model. The method assumes an Inverse Weibull probability distribution for the characterization of extreme wind speeds, and is developed by means of a novel Bayes estimation method. Such method uses a prior assessment of a given quantile of the wind speed by means of a “Negative Log- Lognormal" distribution. In the paper, by means of large set of numerical simulations relevant to typical wind speed data, the efficiency of the Bayes methods is discussed. Attention is focused in particular on the robustness of the estimates with respect to departures from the assumed wind speed probability distributions, assuming the Gumbel distribution as an alternative extreme value model.

This paper is a first step towards the evaluation of the life and reliability of HVDC cable systems in the presence of voltage polarity reversals. It combines a physical-phenomenological life model for HVDC cables subjected to voltage polarity with a recently-developed life model for HVDC cables subjected to load cycles. Under some meaningful approximations, a quite powerful model that accounts both for load cycles and voltage polarity reversal is eventually attained. Such model can be applied in order to predict the life of HVDC cables subjected to voltage polarity reversal tests with load cycles superimposed, performed in line with CIGRE Recommendations after Electra 189, 2000. By doing so, results in agreement with the experience gained by Terna (the Italian TSO) in testing HVDC cables - in particular MIND cables - are attained.

An experimental investigation of the behavior of partial discharges occurring in insulation cavities as a function of light irradiation conditions is presented in this paper. Partial discharge inception voltage (PDIV) measurements were performed for different irradiation conditions of the test objects (visible light, of variable intensity, ultra violet (UV) light or absence of irradiation), defect geometry and conductivity of insulating material. It is shown that changes of such factors involve considerable alteration of partial discharge inception features, in terms of both inception voltage and delay time. Depending on applied field, defect geometry, insulating material characteristics and irradiation condition, in fact, partial discharge inception voltage may be influenced prevailingly by background radiation, as generally stated in literature, or by field-assisted electron detrapping from material-cavity interface.

Techniques for estimating the parameters of the 2-parameter Weibull distribution from data obtained from uncensored tests are compared. This will allow the most convenient method to be chosen by considering the data's characteristics and the level of algorithm complexity. It is shown that common techniques, such as least squares regression and maximum likelihood, may give rise to very significant errors in terms of the bias of the estimated Weibull parameters. The estimator suggested by Jacquelin (1993) for /spl alpha/ and the correction factor suggested by Ross (1994) for /spl beta/ usually give errors of