Regular AC Research Articles

New xylose transporters support the simultaneous consumption of glucose and xylose in Escherichia coli.

Glucose and xylose are two major components of lignocellulose. Simultaneous consumption of glucose and xylose is critical for engineered microorganisms to produce fuels and chemicals from lignocellulosic biomass. Although many production limitations have been resolved, glucose-induced inhibition of xylose transport remains a challenge. In this study, a cell growth-based screening strategy was designed to identify xylose transporters uninhibited by glucose.The glucose pathway was genetically blocked in Escherichia coli so that glucose functions only as an inhibitor and cells need xylose as the carbon source for survival. Through adaptive evolution, omics analysis and reverse metabolic engineering, a new phosphoenolpyruvate: carbohydrate phosphotransferase system (PTS) galactitol transporter (GalABC, encoded by EcolC_1640, EcolC_1641, and EcolC_1642 genes) that is not inhibited by glucose was identified. Inactivation of adenylate cyclase led to increased expression of the EcolC_1642 gene, and a point mutation in gene EcolC_1642 (N13S) further enhanced xylose transport. During the second round of gene mining, AraE and a new ABC transporter (AraFGH) of xylose were identified. A point mutation in the transcription regulator araC (L156I) caused increased expression of araE and araFGH genes without arabinose induction, and a point mutation in araE (D223Y) further enhanced xylose transport. These newly identified xylose transporters can support the simultaneous consumption of glucose and xylose and have potential use in producing chemicals from lignocellulose.

Designing of Lithium - Ion Battery Pack Rechargeable on a Hybrid System with Battery Management System (BMS) for DC Loads of Low Power Applications – A Prototype Model

Now a days, Li-ion batteries are quite possibly the most exceptional battery-powered batteries; these are drawing in much consideration from recent many years. M Whittingham first proposed lithium-ion battery technology in the 1970s, using titanium sulphide for the cathode and lithium metal for the anode. Li-ion batteries are the force to be reckoned with for the advanced electronic upset in this cutting-edge versatile society, solely utilized in cell phones and PC computers. A battery is a Pack of cells organized in an arrangement/equal association so the voltage can be raised to the craving levels. Lithium-ion batteries, which are completely utilised in portable gadgets & electric vehicles, are the driving force behind the digital technological revolution in today’s mobile societies. In order to protect and maintain voltage and current of the battery with in safe limit Battery Management System (BMS) should be used. BMS provides thermal management to the battery, safeguarding it against over and under temperature and also during short circuit conditions. The battery pack is designed with series and parallel connected cells of 3.7v to produce 12v. The charging and releasing levels of the battery pack is indicated by interfacing the Arduino microcontroller. The entire equipment is placed in a fiber glass case (looks like aquarium) in order to protect the battery from external hazards to design an efficient Lithium-ion battery by using Battery Management System (BMS). We give the supply to the battery from solar panel and in the absence of this, from a regular AC supply.

An Emergency Portable Ventilator for COVID Patients with Acute Breathing Difficulty

In this paper, a design of a ventilator that meets the demand for emergency ventilators required to help patients with acute breathing difficulty during pandemics such as the current COVID-19 pandemic is presented. The AMBU bag based ventilator can be fabricated at low cost and is easily affordable by hospitals. Based on readily available components, the ventilator will cost about INR6000, and can be easily maintained by even non-technical medical personnel. It works on regular AC supply of 220V and runs on 12V DC supply drawing about 1.5A current. The ventilator is light in weight weighing about 2Kg and is easily portable. The use of individually addressable light emitting diodes and a photo- resistor for positioning of the pushrod is an innovative feature of the ventilator. It meets the requirement of emergency ventilators for use during the waiting period before a full fledged ventilator is available to the patient.

A tunable l-arabinose-inducible expression plasmid for the acetic acid bacterium Gluconobacter oxydans

The acetic acid bacterium (AAB) Gluconobacter oxydans incompletely oxidizes a wide variety of carbohydrates and is therefore used industrially for oxidative biotransformations. For G. oxydans, no system was available that allows regulatable plasmid-based expression. We found that the l-arabinose-inducible PBAD promoter and the transcriptional regulator AraC from Escherichia coli MC4100 performed very well in G. oxydans. The respective pBBR1-based plasmids showed very low basal expression of the reporters β-glucuronidase and mNeonGreen, up to 480-fold induction with 1% l-arabinose, and tunability from 0.1 to 1% l-arabinose. In G. oxydans 621H, l-arabinose was oxidized by the membrane-bound glucose dehydrogenase, which is absent in the multi-deletion strain BP.6. Nevertheless, AraC-PBAD performed similar in both strains in the exponential phase, indicating that a gene knockout is not required for application of AraC-PBAD in wild-type G. oxydans strains. However, the oxidation product arabinonic acid strongly contributed to the acidification of the growth medium in 621H cultures during the stationary phase, which resulted in drastically decreased reporter activities in 621H (pH 3.3) but not in BP.6 cultures (pH 4.4). These activities could be strongly increased quickly solely by incubating stationary cells in d-mannitol-free medium adjusted to pH 6, indicating that the reporters were hardly degraded yet rather became inactive. In a pH-controlled bioreactor, these reporter activities remained high in the stationary phase (pH 6). Finally, we created a multiple cloning vector with araC-PBAD based on pBBR1MCS-5. Together, we demonstrated superior functionality and good tunability of an AraC-PBAD system in G. oxydans that could possibly also be used in other AAB.Key points• We found the AraC-PBADsystem from E. coli MC4100 was well tunable in G. oxydans.• In the absence of AraC orl-arabinose, expression from PBADwas extremely low.• This araC-PBADsystem could also be fully functional in other acetic acid bacteria.

Power Factor Analysis and Maximum Power Factor Control Strategy for Six-Phase DC-Biased Vernier Reluctance Machines

Different from the regular ac machines, the armature winding current waveforms of dc-biased vernier reluctance machines (DC-biased-VRMs) are sinusoidal with dc bias. The power factor (PF) calculation process also shows great difference. This paper intends to analyze the PF theoretically based on the mathematical model. Then, investigate the approach to optimize the PF and the price to pay if measures are taken to further improve the PF. The PF of the DC-biased-VRM is expressed under synchronous rotating frame. A maximum PF control strategy is proposed by adjusting the distribution of three-dimensional dq 0-axis currents. The scale of active power to reactive power is changed, and the PF can be regulated. Experimental results are provided to verify the validity of the theoretical analysis.

Power Converter Topologies and Control Strategies for DC-Biased Vernier Reluctance Machines

This paper investigates the two latest proposed drive system topologies for dc-biased vernier reluctance machines (VRMs), aims to find out the preferable drive system configuration, and explains the performance discrepancy between the two configurations. Different from the regular ac machines, the armature winding current waveforms of dc-biased VRMs are sinusoidal with dc bias. To provide the dc flow path, the two drive system topologies are associated with the machine, namely, an open winding converter with single-layer concentrated winding and a dual three-phase converter with double-layer concentrated winding. The two configurations are investigated and compared in terms of machine operation principle, power converter configuration, voltage utilization, system cost, and system efficiency. The theoretical analyses and experimental results validate that the two drive systems have their respective advantages.

A growth- and bioluminescence-based bioreporter for the invivo detection of novel biocatalysts.

SummaryThe use of bioreporters in high‐throughput screening for small molecules is generally laborious and/or expensive. The technology can be simplified by coupling the generation of a desired compound to cell survival, causing only positive cells to stay in the pool of generated variants. Here, a dual selection/screening system was developed for the in vivo detection of novel biocatalysts. The sensor part of the system is based on the transcriptional regulator AraC, which controls expression of both a selection reporter (LeuB or KmR; enabling growth) for rapid reduction of the initially large library size and a screening reporter (LuxCDABE; causing bioluminescence) for further quantification of the positive variants. Of four developed systems, the best system was the medium copy system with KmR as selection reporter. As a proof of principle, the system was tested for the selection of cells expressing an l‐arabinose isomerase derived from mesophilic Escherichia coli or thermophilic Geobacillus thermodenitrificans. A more than a millionfold enrichment of cells with l‐arabinose isomerase activity was demonstrated by selection and exclusion of false positives by screening. This dual selection/screening system is an important step towards an improved detection method for small molecules, and thereby for finding novel biocatalysts.

Ac to Ac Frequency Changer THD Reduction Based on Selective Harmonic Elimination

AC to AC frequency converters had a challenge to be proposed as a reduction of THD. This challenge due to eliminate the most effective harmonics in frequency spectrum with low cost and no difficulty. However, the challenge is represented by producing new technique for AC to AC frequency changer with lower total harmonic distortion compared with regular AC to AC frequency changer. This proposed work introduces reduction based on eliminate the 3rd predominant harmonic by imposing a waveform with same frequency, amplitude and poly phase of presented harmful harmonic the elimination for the most effective harmonic will cause reduction in THD . The proposed technique gave a significant reduction in THD (about 52%) with respect to regular AC to AC frequency changer with low cost implementation requirements.

DC'S low-voltage invasion

What do you do when you find a financial crash has left your shiny new data centre empty? In Intel's case, it provided the opportunity to find out whether a move from AC to DC distribution might save on its electricity costs. When bundles of sub-prime loans imploded and took the economy with them in 2008, the world's largest chipmaker found it no longer had an immediate use for a new data centre built to support manufacturing at its plant west of Portland, Oregon. Working with HP and Emerson Network Power, Intel reworked the 5MW electrical distribution network at the data centre to handle 380V of DC instead of the regular AC. The project followed on from earlier experiments at the Lawrence Berkeley National Laboratory (LBNL), 1,000km south of the Intel fab, which found that a shift to DC could improve energy efficiency by close to 30 per cent.

Virulence Gene Regulation by L-Arabinose in Salmonella enterica.

Invasion of the intestinal epithelium is a critical step in Salmonella enterica infection and requires functions encoded in the gene cluster known as Salmonella Pathogenicity Island 1 (SPI-1). Expression of SPI-1 genes is repressed by L-arabinose, and not by other pentoses. Transport of L-arabinose is necessary to repress SPI-1; however, repression is independent of L-arabinose metabolism and of the L-arabinose-responsive regulator AraC. SPI-1 repression by L-arabinose is exerted at a single target, HilD, and the mechanism appears to be post-translational. As a consequence of SPI-1 repression, l-arabinose reduces translocation of SPI-1 effectors to epithelial cells and decreases Salmonella invasion in vitro. These observations reveal a hitherto unknown role of L-arabinose in gene expression control and raise the possibility that Salmonella may use L-arabinose as an environmental signal.

Characterization of nano-lead-doped active carbon and its application in lead-acid battery

In this paper, nano-lead-doped active carbon (nano-Pb/AC) composite with low hydrogen evolution current for lead-acid battery was prepared by ultrasonic-absorption and chemical-precipitate method. The nano-Pb/AC composite was characterized by SEM, EDS and TEM. The electrochemical characterizations are performed by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in a three-electrode system. Since intermediate adsorption is the rate-determining step, the hydrogen evolution reaction (HER) is markedly inhibited as the intermediate adsorption impedance of nano-Pb/AC increased. Meanwhile, the working potential of nano-Pb/AC is widened to the whole potential region of Pb negative plate (from −1.36 V to −0.86 V vs. Hg/HgSO4) in lead-acid battery. In addition, nano-Pb can improve the interfacial compatibility between AC and Pb paste, accordingly relieve the symptoms of carbon floatation. Finally, 2.0 V single-cell flooded lead-acid batteries with 1.0 wt.% nano-Pb/AC or 1.0 wt.% AC addition in negative active materials are assembled. The cell performances test results show that the 3 h rate capacity, quick charging performance, high current discharging performance and cycling performance of nano-Pb/AC modified battery are all improved compared with regular lead-acid battery and AC modified lead-acid battery.

Development and Application of an Arabinose-Inducible Expression System by Facilitating Inducer Uptake in Corynebacterium glutamicum

Corynebacterium glutamicum is currently used for the industrial production of a variety of biological materials. Many available inducible expression systems in this species use lac-derived promoters from Escherichia coli that exhibit much lower levels of inducible expression and leaky basal expression. We developed an arabinose-inducible expression system that contains the L-arabinose regulator AraC, the P(BAD) promoter from the araBAD operon, and the L-arabinose transporter AraE, all of which are derived from E. coli. The level of inducible P(BAD)-based expression could be modulated over a wide concentration range from 0.001 to 0.4% L-arabinose. This system tightly controlled the expression of the uracil phosphoribosyltransferase without leaky expression. When the gene encoding green fluorescent protein (GFP) was under the control of P(BAD) promoter, flow cytometry analysis showed that GFP was expressed in a highly homogeneous profile throughout the cell population. In contrast to the case in E. coli, P(BAD) induction was not significantly affected in the presence of different carbon sources in C. glutamicum, which makes it useful in fermentation applications. We used this system to regulate the expression of the odhI gene from C. glutamicum, which encodes an inhibitor of α-oxoglutarate dehydrogenase, resulting in high levels of glutamate production (up to 13.7 mM) under biotin nonlimiting conditions. This system provides an efficient tool available for molecular biology and metabolic engineering of C. glutamicum.

Negative auto-regulation increases the input dynamic-range of the arabinose system of Escherichia coli

BackgroundGene regulation networks are made of recurring regulatory patterns, called network motifs. One of the most common network motifs is negative auto-regulation, in which a transcription factor represses its own production. Negative auto-regulation has several potential functions: it can shorten the response time (time to reach halfway to steady-state), stabilize expression against noise, and linearize the gene's input-output response curve. This latter function of negative auto-regulation, which increases the range of input signals over which downstream genes respond, has been studied by theory and synthetic gene circuits. Here we ask whether negative auto-regulation preserves this function also in the context of a natural system, where it is embedded within many additional interactions. To address this, we studied the negative auto-regulation motif in the arabinose utilization system of Escherichia coli, in which negative auto-regulation is part of a complex regulatory network.ResultsWe find that when negative auto-regulation is disrupted by placing the regulator araC under constitutive expression, the input dynamic range of the arabinose system is reduced by 10-fold. The apparent Hill coefficient of the induction curve changes from about n = 1 with negative auto-regulation, to about n = 2 when it is disrupted. We present a mathematical model that describes how negative auto-regulation can increase input dynamic-range, by coupling the transcription factor protein level to the input signal.ConclusionsHere we demonstrate that the negative auto-regulation motif in the native arabinose system of Escherichia coli increases the range of arabinose signals over which the system can respond. In this way, negative auto-regulation may help to increase the input dynamic-range while maintaining the specificity of cooperative regulatory systems. This function may contribute to explaining the common occurrence of negative auto-regulation in biological systems.

Hybrid Ventilation System Simulation for Several Cities in Turkey

Hybrid ventilation systems combine the superior properties of natural and mechanical ventilation systems to reduce energy consumption. In this study, hybrid ventilation simulations were performed for several cities in Turkey, which have different climate conditions. Matlab/Simulink was utilized to perform the simulations. The results of these simulations were compared with that of regular air conditioning units in terms of energy consumption. A hybrid ventilation system which shows the general behaviour of a fan-assisted natural ventilation system with temperature-based control and which provides both heating and cooling, is shown to be effective for four cities in Turkey that have different climate conditions. Results showed potential savings of around 25–30% when compared to a regular AC system.

Optimal Design of a Hybrid-Driven Servo Press and Experimental Verification

This paper focuses on a hybrid-driven servo press, which uses not only a servomotor but also a regular ac motor with a flywheel. A PC-based control system is developed based on both feedback and iterative learning control theories on a prototype. The stamping performance, improved forming ability, and energy saving merits have been verified by the experiment. The results show that the advantages of the hybrid-driven servo press have been validated, such as its energy saving features, flexible punch speeds, and adjustable strokes, for any kind of stamping operations.

Attaching single carbon nanotube on tip's apex using dielectrophoresis of DC-pulse voltage

Single carbon nanotubes (CNTs) are candidates for a number of electronics and sensing applications, provided that single CNTs can be separated from a bundle of CNTs in suspension. Dielectrophoresis has recently been demonstrated as one route for the extraction of desired CNTs. However, previous methods using dielectrophoresis have found it difficult to extract single nanotubes from bundles of CNTs in solution. Here, we show that this restriction can be overcome by using pulsed DC voltage of an electric field, instead of regular AC and DC voltages.

Irregular AC losses with long time constants in large cable-in-conduit conductors

A large superconducting coil wound with Cable-in-Conduit (CIC) conductor causes both irregular AC losses that cannot be estimated from short conductor sample test results, and regular AC losses that are proportional to cable twisting pitch squared. We proposed a mechanism forming loops that generated the irregular losses. The CIC conductor is composed of several stages of sub-cables. If one strand on the surface of a sub-cable contacts another strand on the surface of the adjacent sub-cable, the two strands must encounter each other again at the LCM (Least Common Multiplier) distance of all staged cable pitches, and thereby a long loop is formed. We orderly labeled all strands in CIC conductors for the SMES and the LHD. It was found that strands in a triplet were widely displaced from their original positions on one cross section, but contacted each other tightly on the other cross section. This fact suggests that the loop with the large displaced strand links irregularly with external field so that the loops cause the irregular AC losses. Moreover, it indicates that a contacting length of the large displaced strands can be quite long, giving rise to a low contact resistance for the loop, and leading to the long time constants. It is believed that the widely displaced strand are inherent in a CIC conductor. It was demonstrated that the strand surface coated with CuNi was effective to suppress the irregular AC losses.

Loss of consciousness from epidural sufentanil for labour analgesia

Loss of consciousness from epidural sufentanil for labour analgesia

Regulation of Functional Activity of Adenylyl Cyclase Signal System by Synthetic Coil-Forming Peptides in Mouse Fibroblast Culture of Line L (ISM Subline)

The signal transduction process via adenylyl cyclase system (ACS) requires coordinated functioning of signal proteins—components of ACS. It is suggested that functional coupling between them, together with other molecular mechanisms, is based on coiled-coil interactions. To study role of these interactions in functioning of ACS, we synthesized cationic coiled-forming peptides with a regular structure Ac–Ala–His– (Ala)2–His–Ala–NH2 (I), Ac–Ala–His–(Ala)3–His– (Ala)2–His–Ala–NH2 (II), and Ac–(Pro(2–His– (Ala)2–His– (Ala)2–His– (Ala)2–His–Ala–NH2 (III). Using circular dichroism (CD) spectroscopy, a portion of α-helix conformation in their secondary structure was determined, and effects of these peptides on basal adenylyl cyclase (AC) activity as well as on the activity stimulated by non-hormonal (NaF and Gpp[NH]p) and hormonal (serotonin) agents was studied in homogenate of mouse fibroblasts, line L (subline LSM). The synthetic peptides were shown to inhibit in a dose-dependent manner both basal and induced AC activity, which indicates their uncoupling action on ACS. The biological effect of these peptides correlated with their length (I < II < III), but not with coiled-coil structure, which was 20, 7, and 21%, respectively, according to data of circular dichroism spectroscopy in 3-fluoroethanol. However, there are reasons to believe that the coiled-coil structure of peptides, first place extended ones, increases at interaction with plasma membrane and signal proteins, which affects the degree of their effect on functional ACS activity. At micromolar concentrations, peptides II and III were established to markedly stimulate the basal AC activity, thereby mimicking G-protein-binding sites of cytoplasmic receptor loops. The data obtained indicate participation of the coiled-coil interactions in functional coupling of ACS components, and the methodology itself of the use of model peptides with different coiled-coil structure and distribution of charged amino acids is an efficient approach for studying molecular bases for functioning of signal systems.

Design and implementation of a 25-kVA three-phase PWM AC line conditioner

In this paper, an improved version of PWM AC line conditioners is proposed. As compared to previously reported structures, it uses fewer standard switch modules. This, in combination with less stringent gating requirements, improves the overall operating reliability of the system. In addition, it retains the same advantages of a regular force-commutated AC line conditioner, including sinusoidal input-output waveforms, fast dynamic response, and small input-output filters. The operating principle of the proposed structure is discussed, and the voltage feedback loop design is analyzed. Results from a 25 kVA experimental setup are provided for verification. >