The DC-Link capacitor plays a crucial role as far as power density and reliability are concerned: it occupies approximately 40% of the inverter, and causes approximately 30% of its failures. Asymmetrical dual three-phase (ADTP) multiphase arrangements are gaining relevance in the automotive sector for powertrain applications. This work focuses on reducing the impact that the widely used double zero sequence injection (DZSI) family of PWM techniques have on such a bulky and failure-prone component in an ADTP arrangement by means of interleaving techniques. By using the double Fourier integral formalism, the input current spectra and the overall performance of these PWM techniques have been derived, in terms of current rms value and voltage ripple in the DC-Link capacitor. Simulations have shown that choosing an adequate interleaving scheme and angle considerably relieves both current and voltage stresses on the DC-Link capacitor compared to noninterleaved operation. Reductions of 84% current rms and 86% voltage ripple have been achieved at static operating points. Finally, by averaging the rms current over WLTP standard driving cycle, reductions up to 26% have been obtained under more realistic conditions. All this would enhance the reliability and reduce the size of the onboard capacitors in future electric vehicles.

Multiphase drives are becoming a viable alternative to three-phase drives in electric traction applications, thanks to a number of benefits that offset the additional cost, e.g. smoother torque performance, higher current capability, enhanced fault tolerance, higher efficiency, and lower DC-Link current ripples. This work focuses on the impact that continuous and discontinuous PWM techniques have on such a costly and bulky component as the DC-Link capacitor, in a multiphase arrangement. Because the equivalent series resistance (ESR) of the DC-Link capacitor varies with frequency, the typical current RMS-based power loss approximation is often inaccurate. Thus, the current spectrum-based power loss estimation has been carried out for the five-phase two-level voltage source inverter (VSI). In this scenario, and switching at about 100 kHz, a MKP capacitor has shown to suffer lower power losses when discontinuous PWM techniques are used.

The shorter switching times of silicon carbide (SiC) MOSFETs enable power converters to operate at higher frequencies than with silicon IGBTs. However, because SiC MOSFET die sizes are still relatively small, several devices have to be connected in parallel to cope with the high current ratings demanded. For the total current to be evenly distributed among all the MOSFETs, the gate circuit and power layout must meet stringent symmetry requirements. However, space limitations on the circuit surface hinders the achievement of full symmetries on both the power and gate layouts because they constrain one another. This paper proposes a solution for safely paralleling discrete SiC MOSFETs while decoupling the gate and power layout designs. It requires placing one BJT-based fast current amplifier as close as possible to each MOSFET rather than using just one to feed all the MOS gates. This reduces the noise in the received gating signals and, more importantly, reduces the sensitivity of driver-gate path geometric / electric mismatches. This makes it possible to safely relax the symmetry requirements for the gating circuitry, thereby providing designers with more freedom to achieve better symmetry in the power layout.

Common-mode voltage (CMV) produces serious reliability and electromagnetic interference (EMI) issues in modern pulse-width modulated (PWM) electric drives. Such issues will become more prominent in the near future, as industry moves towards the introduction of wide-bandgap (WBG) semiconductor technologies operating at higher switching frequencies and also with greater dvdt. In this context, multiphase electric drive technologies can be of great interest, as their additional degrees of freedom can be exploited to reduce CMV. This work aims to study the potential of multiphase electric motor drive systems for CMV mitigation. To do so, a comprehensive review of the most recent scientific literature is conducted, mainly focusing on high impact works published recently. As a result, a clear and up-to-date picture of the most common multiphase technologies, i.e., (m+1)-leg, multiple three-phase, open-end and star-connected multiphase systems is provided along with their CMV reduction potential. Not only the topologies themselves but also modulation techniques are analysed and presented, mainly focusing on star-connected systems. As a conclusion, it can be stated that such multiphase systems are promising candidates to substitute conventional three-phase motor drives as, apart from their well-known advantages (efficiency, power density, power splitting, and fault tolerance), their CMV reduction potential is confirmed. The technical information provided in this work will help researchers and field engineers to design and develop high-performance multiphase electric drives.

In traction applications, particularly in transport electrification, multiphase drives are becoming an alternative to their three-phase counterparts due to a range of advantages outweighing the additional cost, e.g. smoother torque performance, higher current capability, enhanced fault tolerance, and higher efficiency. In this context, it is interesting to reevaluate the modulation techniques in order to account for the particularities of multiphase systems. In this work the most widely used modulation techniques are assessed, but assuming a five-phase arrangement, in terms of several well-established figures-of-merit pertaining to the inverter power losses, input performance (current RMS, voltage ripple), and output performance (current ripple and common-mode voltage). Thus, this work provides a global vision of how the selected modulation technique, as well as the modulation index and the load’s current phase angle, affect the performance of the multiphase electric motor drive systems.

Organic contaminants significantly limit the bioactivity of titanium implants, resulting in the degradation known as the ageing of titanium. To reactivate the surfaces, they can be photofunctionalized, i.e., irradiated with C-range ultraviolet (UVC) light. This descriptive in vitro study compares the effectiveness of novel light-emitting diode (LED) technology to remove contaminant hydrocarbons from three different commercially available titanium dental implants: THD, TiUnite, and SLA. The surface topography and morphology were characterized by scanning electron microscopy (SEM). The chemical compositions were analyzed by X-ray photoelectron spectroscopy (XPS), before and after the lighting treatment, by a pair of closely placed UVC (λ = 278 nm) and LED devices for 24 h. SEM analysis showed morphological differences at the macro- and micro-scopic level. XPS analysis showed a remarkable reduction in the carbon contents after the UVC treatment: from 25.6 to 19.5 C at. % (carbon atomic concentration) in the THD; from 30.2 to 20.2 C at. % in the TiUnite; from 26.1 to 19.2 C at. % in the SLA surface. Simultaneously, the concentration of oxygen and titanium increased. Therefore, LED-based UVC irradiation decontaminated titanium surfaces and improved the chemical features of them, regardless of the kind of surface.

The demand for more reliable and efficient electric machines and drives is constantly growing in the renewable energy and transport electrification sectors. Such drive systems are usually fed by semiconductor switch-based inverters, which, unlike balanced pure sine-wave AC sources, produce large-amplitude, high-frequency common-mode voltage (CMV) waveforms, as a result of the application of pulse-width modulation (PWM). This can lead to a number of issues, such as high electromagnetic interference, deterioration of stator winding insulation, and leakage current flow through motor bearings, which dramatically reduce the life-cycle of machines and drives. Thus, this topic has been extensively investigated in the scientific literature, where either corrective or preventive mitigation approaches have been proposed. The former attempt to relieve the damage produced, whereas the latter tackle the problem at its root, by minimizing or eliminating the CMV produced by the inverter. This work provides a comprehensive review of the major CMV mitigation/elimination solutions, with emphasis on preventive actions, in the form of inverter topology variants and/or advanced modulation techniques. A wide picture of this subject is provided to researchers and field engineers, with valuable information and practical hints for the design and development of high-performance electric drive systems. Indeed, an in-depth analysis of the most recent literature clearly shows that best results are obtained by conveniently combining alternative topologies and modulation techniques, which, in some cases, make it possible to completely suppress the CMV component.

Tolerance of microorganisms to abiotic stress is enabled by regulatory mechanisms that coordinate the expression and activity of resistance genes. Alkalinity and high salt concentrations are major environmental physicochemical stresses. Here, we analyzed the roles of sodium-extrusion family (ENA) transporters EnaA, EnaB and EnaC in the response to these stress conditions in the filamentous fungus Aspergillus nidulans. While EnaC has a minor role, EnaB is a key element for tolerance to Na+ and Li+ toxicity. Adaptation to alkaline pH requires the concerted action of EnaB with EnaA. Accordingly, expression of enaA and enaB was induced by Na+, Li+ and pH 8. These expression patterns are altered in a sltAΔ background and completely inhibited in a mutant expressing non-functional PacC protein (palH72). However, a constitutively active PacC form was not sufficient to restore maximum enaA expression. In agreement with their predicted role as membrane ATPases, EnaA localized to the plasma membrane while EnaB accumulated at structures resembling the endoplasmic reticulum. Overall, results suggest different PacC- and SltA-dependent roles for EnaB in pH and salt homeostasis, acting in coordination with EnaA at pH 8 but independently under salt stress.

C-range Ultraviolet (UVC) mercury (Hg)-vapor lamps have shown the successful decontamination of hydrocarbons and antimicrobial effects from titanium surfaces. This study focused on surface chemistry modifications of titanium dental implants by using two different light sources, Hg-vapor lamps and Light Emitting Diodes (LEDs), so as to compare the effectivity of both photofunctionalization technologies. Two different devices, a small Hg-vapor lamp (λ = 254 nm) and a pair of closely placed LEDs (λ = 278 nm), were used to irradiate the implants for 12 min. X-ray Photoelectron Spectroscopy (XPS) was employed to characterize the chemical composition of the surfaces, analysing the samples before and after the lighting treatment, performing a wide and narrow scan around the energy peaks of carbon, oxygen and titanium. XPS analysis showed a reduction in the concentration of surface hydrocarbons in both UVC technologies from around 26 to 23.4 C at.% (carbon atomic concentration). Besides, simultaneously, an increase in concentration of oxygen and titanium was observed. LED-based UVC photofunctionalization has been suggested to be as effective a method as Hg-vapor lamps to remove the hydrocarbons from the surface of titanium dental implants. Therefore, due to the increase in worldwide mercury limitations, LED-based technology could be a good alternative decontamination source.

Switched Reluctance Machines (SRM) are emerging as a possible alternative in terms of cost and supply stability to rare earth based electric vehicle traction systems. However, because of the huge amounts of energy stored and transferred back and forth between the DC source and the SRM, large DC-link capacitors must be used as buffers, which increases overall costs and size. This paper proposes a novel modulation technique which forces the exchange of energy between phases while decreasing the energy transfer between the DC bus and the SRM. This means lower DC bus currents (capacitor size and cost reduction) and lower Joule-effect conduction losses (better efficiency). The proposed modulation has been validated experimentally in a test bench and compared with the conventional torque-sharing function.

Copper ion homeostasis involves a finely tuned and complex multi-level response system. This study expands on various aspects of the system in the model filamentous fungus Aspergillus nidulans. An RNA-seq screen in standard growth and copper toxicity conditions revealed expression changes in key copper response elements, providing an insight into their coordinated functions. The same study allowed for the deeper characterization of the two high-affinity copper transporters: AnCtrA and AnCtrC. In mild copper deficiency conditions, the null mutant of AnctrC resulted in secondary level copper limitation effects, while deletion of AnctrA resulted in primary level copper limitation effects under extreme copper scarcity conditions. Each transporter followed a characteristic expression and cellular localization pattern. Although both proteins partially localized at the plasma membrane, AnCtrC was visible at membranes that resembled the ER, whilst a substantial pool of AnCtrA accumulated in vesicular structures resembling endosomes. Altogether, our results support the view that AnCtrC plays a major role in covering the nutritional copper requirements and AnCtrA acts as a specific transporter for extreme copper deficiency scenarios.

Copper is a metal ion that is required as a micronutrient for growth and proliferation. However, copper accumulation generates toxicity by multiple mechanisms, potentially leading to cell death. Due to its toxic nature at high concentrations, different chemical variants of copper have been extensively used as antifungal agents in agriculture and medicine. Most studies on copper homeostasis have been carried out in bacteria, yeast, and mammalian organisms. However, knowledge on filamentous fungi is less well documented. This review summarizes the knowledge gathered in the last few years about copper homeostasis in the filamentous fungi Aspergillus fumigatus and Aspergillus nidulans: The mechanism of action of copper, the uptake and detoxification systems, their regulation at the transcriptional level, and the role of copper homeostasis in fungal pathogenicity are presented.

Background The surface chemistry of titanium (Ti) dental implants is considered to be one of the crucial factors contributing to successful osseointegration. Additionally, ultraviolet (UV) light is known to alter the chemical behaviour of the Ti oxide that inevitably or purposely surrounds every all Ti implants. As a result, a growing number of authors propose to irradiate these implants with UV light prior to their placement in the oral cavity, in a process called photofunctionalization. Aim/Hypothesis The aim of this comparative in-vitro study is to gain insight into how effective the photofunctionalization can be when applied to three different Ti dental implants, of varying commercial brands and therefore having distinctive surface chemistry and topography. Material and Methods Three different Ti dental implants (SteriOss Inc. THD+ Nobel Biocare TiUnite+ Straumann SLA), were irradiated by a pair of closely placed Light Emitting Diode (LED) devices producing C-range UV light (UVC, λ=278 nm) for 24 hours. X-ray Photoelectron Spectroscopy (XPS) was used to analyse the chemical composition of the surfaces before and after treatment. In both cases, first, a wide scan analysis was conducted to detect the elements present on the three samples, and then, detailed scans were performed around the bounding energy peaks of titanium, oxygen and carbon, in order to quantify their relative concentration. Along with that, Scanning Electron Microscopy (SEM) was employed to characterize the surface topography and morphology of the three implants. Results The surface properties changed according to the manufacturing and surface modification treatment methods used. XPS analysis showed a reduction in the concentration of hydrocarbons in the oxide layer in all the samples, after UVC irradiation, from 25.6 to 19.5 C at. % (carbon atomic concentration) in the SteriOss THD implant+ from 30.2 to 20.2 C at. % in the Nobel Biocare TiUnite implant+ and from 26.1 to 19.2 C at. % in Straumann SLA implant. Indeed, higher amounts of hydrocarbons were observed in the TiUnite surface. Together with that, an increase in the concentration of oxygen and titanium was demonstrated, which is related to an enhancement of osseointegration. SEM analysis showed morphological differences at microscopic level between three samples. Conclusion and Clinical Implications UVC LED-based irradiation reduced the hydrocarbons in the oxide layer regardless of the kind of titanium surface. This suggests UVC LED-based technology can be a successful alternative to the implementation of the photofunctionalization in Ti implants and thus improving the bone-material interactions and resulting in a better development of the osseointegration.

FluG is a long recognized early regulator of asexual development in Aspergillus nidulans. fluG null mutants show profuse aerial growth and no conidial production. Initial studies reported sequence homology of FluG with a prokaryotic type I glutamine synthetase, but catalytic activity has not been demonstrated. In this study, we conducted an in-depth analysis of the FluG sequence, which revealed a single polypeptide containing a putative N-terminal amidohydrolase region linked to a putative C-terminal γ-glutamyl ligase region. Each region corresponded, separately and completely, to respective single function bacterial enzymes. Separate expression of these regions confirmed that the C-terminal region was essential for asexual development. The N-terminal region alone did not support conidial development, but contributed to increased conidial production under high nutrient availability. Point mutations directed at respective key catalytic residues in each region demonstrated that they were essential for biological function. Moreover, the substitution of the N- and C-terminal regions with homologs from Lactobacillus paracasei and Pseudomonas aeruginosa, respectively, maintained functionality, albeit with altered characteristics. Taken together, the results lead us to conclude that FluG is a bifunctional enzyme that participates in an as yet unidentified metabolic or signaling pathway involving a γ-glutamylated intermediate that contributes to developmental fate.

Copper homeostasis has been extensively studied in mammals, bacteria, and yeast, but it has not been well-documented in filamentous fungi. In this report, we investigated the basis of copper tolerance in the model fungus Aspergillus nidulans. Three genes involved in copper homeostasis have been characterized. First, crpA the A. nidulans ortholog of Candida albicans CaCRP1 gene encoding a PI-type ATPase was identified. The phenotype of crpA deletion led to a severe sensitivity to Cu+2 toxicity and a characteristic morphological growth defect in the presence of high copper concentration. CrpA displayed some promiscuity regarding metal species response. The expression pattern of crpA showed an initial strong elevation of mRNA and a low continuous gene expression in response to long term toxic copper levels. Coinciding with maximum protein expression level, CrpA was localized close to the cellular surface, however protein distribution across diverse organelles suggests a complex regulated trafficking process. Secondly, aceA gene, encoding a transcription factor was identified and deleted, resulting in an even more extreme copper sensitivity than the ΔcrpA mutant. Protein expression assays corroborated that AceA was necessary for metal inducible expression of CrpA, but not CrdA, a putative metallothionein the function of which has yet to be elucidated.

Microbial cells interact with the environment by adapting to external changes. Signal transduction pathways participate in both sensing and responding in the form of modification of gene expression patterns, enabling cell survival. The filamentous fungal-specific SltA pathway regulates tolerance to alkalinity, elevated cation concentrations and, as shown in this work, also stress conditions induced by borates. Growth of sltA− mutants is inhibited by increasing millimolar concentrations of boric acid or borax (sodium tetraborate). In an attempt to identify genes required for boron-stress response, we determined the boric acid or borax-dependent expression of sbtA and sbtB, orthologs of Saccharomyces cerevisiae bor1, and a reduction in their transcript levels in a ΔsltA mutant. Deletion of sbtA, but mainly that of sbtB, decreased the tolerance to boric acid or borax. In contrast, null mutants of genes coding for additional transporters of the Solute Carrier (SLC) family, sB, sbtD or sbtE, showed an unaltered growth pattern under the same stress conditions. Taken together, our results suggest that the SltA pathway induces, through SbtA and SbtB, the export of toxic concentrations of borates, which have largely recognized antimicrobial properties.

In the model fungus Aspergillus nidulans, asexual development is induced from vegetative hyphae by a set of early regulators including the bZIP-type transcription factor FlbB. To determine the range of genes under the influence of the transcriptional activity of FlbB and to characterize their role in fungal development, we sequenced and compared the transcriptomes of a ΔflbB mutant and its isogenic wild-type strain at different developmental stages. Results confirmed the activating role of FlbB on downstream regulators of conidiation such as flbD and brlA. However, FlbB has additional functions beyond the induction of asexual development. Among the changes observed, absence of a functional FlbB caused induction of the dba cluster and synthesis of a secondary metabolite with bactericidal properties. In addition, a new transcriptional target of FlbB was unveiled, urdA, that codes for a putative transcription factor that represses premature sexual development. Taken together, our results indicate that the activators of asexual development simultaneously exert a role on other cellular functions, including an inhibitory effect on the sexual cycle, and reinforce the hypothesis that mutually exclusive metabolic and cellular patterns are associated with different morphogenetic programs.

In Aspergillus nidulans, asexual differentiation requires the presence of the transcription factor FlbB at the cell tip and apical nuclei. Understanding the relationship between these two pools is crucial for elucidating the biochemical processes mediating conidia production. Tip-to-nucleus communication was demonstrated by photo-convertible FlbB::Dendra2 visualization. Tip localization of FlbB depends on Cys382 in the C-terminus and the bZIP DNA-binding domain in the N-terminus. FlbE, a critical FlbB interactor, binds the bZIP domain. Furthermore, the absence of FlbE results in loss of tip localization but not nuclear accumulation. flbE deletion also abrogates transcriptional activity indicating that FlbB gains transcriptional competence from interactions with FlbE at the tip. Finally, a bipartite nuclear localization signal is required for nuclear localization of FlbB. Those motifs of FlbB may play various roles in the sequence of events necessary for the distribution and activation of this transcriptionally active developmental factor. The tip accumulation, FlbE-dependent activation, transport and nuclear import sketch out a process of relaying an environmentally triggered signal from the tip to the nuclei. As the first known instance of transcription factor-mediated tip-to-nucleus communication in filamentous fungi, this provides a general framework for analyses focused on elucidating the set of molecular mechanisms coupling apical signals to transcriptional events.

In this study, the authors show that it is particularly advantageous to use the fractional-order hold (FROH) instead of the zero-order hold (ZOH) in the digital control of lightly damped resonant systems, as far as transient energy consumption is concerned. First, they show that for a typical digital controller choice FROH reconstruction may well produce a continuous-time signal with less associated energy than ZOH reconstruction. Second, they focus on lightly damped resonant systems, where high energy savings are likely to occur because of the initially swinging nature of the discrete-time control signals driving these systems. Then, they propose an easy procedure to tune the FROH, which is not bound to z-domain controller design, and is therefore radically different from most, if not all, procedures published so far. Finally, they provide some simulation-based application examples confirming the significant control energy reduction attained, in excess of 50%, while not hindering the output performance.