Body effect up- and down-conversion mixer circuits for low-voltage ultra-wideband operation

This article presents fully differential up- and down-conversion mixer circuits manufactured in a triple well 45 nm CMOS process for low-voltage Ultra-Wideband transmitter and receiver applications. The proposed circuits both employ the transistor bulk terminal for signal injection. While the down-conversion mixer uses the bulk for switching via threshold voltage modulation, the up-conversion mixer applies the baseband signal to the bulk, thereby implicitly incorporating the back-gate controlled current source of the MOS transistor. Both circuits offer resistive on-chip termination and DC coupled output buffering for measurement purposes. The down-conversion mixer features an input-referred compression point of −13.2 dBm and a maximum conversion gain of 9.4 dB at 2.5 GHz with the 3-dB corner frequency being beyond 10 GHz. The implemented up-conversion mixer offers a maximum conversion gain of −8.8 dB at 5.8 GHz together with an output-referred compression point of −9.7 dBm. The operational bandwidth ranges from 4.5 to 6.7 GHz. Both circuits operate at a low supply voltage of 1.1 V.     

Impedance study of protecting film formation on lithium and lithiated graphite induced by bis(fluorosulfonyl) imide anion

The process of Li⁺ reduction from room temperature ionic liquids consisting of N-methyl-N-propylpyrrolidinium cation (MPPyr⁺) and bis(fluorosulfonyl) imide (FSI⁻) or bis(trifluoromethanesulfonyl) imide (TFSI⁻) anions was studied with the use of impedance spectroscopy. Reduction was carried out on both metallic lithium (Li) and graphite (G) electrodes. It has been found that the FSI anion in high amounts is able to form a protective film on both graphite and metallic lithium. The Li⁺/Li couple should rather be represented by a Li⁺/SEI/Li system. The SEI structure depends on the manner of its formation (chemical or electrochemical) and is not stable with time. The rate constant for the Li⁺ + e⁻ → Li process at the Li/SEI/Li⁺ (in MPPyrFSI) interface is k_o = 4.2 × 10⁻⁵ cm/s. In the case of carbon electrodes (G/SEI/Li⁺ interface), lithium diffusion in solid graphite is the rate determining step, reducing current by ca. two orders of magnitude, from ca. 10⁻⁴ A/cm², characteristic of the Li/SEI/Li⁺ electrode, to ca. 10⁻⁶ A/cm².     

Combined nitritation-anammox: advances in understanding process stability

Efficient nitrogen removal from wastewater containing high concentrations of ammonium but little organic substrate has recently been demonstrated by several full-scale applications of the combined nitritation-anammox process. While the process efficiency is in most cases very good, process instabilities have been observed to result in temporary process failures. In the current study, conditions resulting in instability and strategies to regain efficient operation were evaluated. First, data from full-scale operation is presented, showing a sudden partial loss of activity followed by recovery within less than 1 month. Results from laboratory-scale experiments indicate that these dynamics observed in full scale can be caused by partial inhibition of the ammonia oxidizing bacteria (AOB), while anammox inhibition is a secondary effect due to temporarily reduced O(2) depletion. Complete anammox inhibition is observed at 0.2 mg O(2) · L(-1), resulting in NO(2)(-) accumulation. However, this inhibition of anammox is reversible within minutes after O(2) depletion. Thus, variable AOB activity was identified as the key to reactor stability. With appropriate interpretation of the online NH(4)(+) signal, accumulation of NO(2)(-) can be detected indirectly and used to signal an imbalance of O(2) supply and AOB activity (no suitable online NO(2)(-) electrode is currently available). Second, increased abundance of nitrite-oxidizing bacteria (NOB; competing with anammox for NO(2)(-)) is known as another cause of instability. Based on a comparison of parallel full-scale reactors, it is suggested that an infrequent and short-term increased O(2) supply (e.g., for maintenance of aerators) that exceeds prompt depletion of oxygen by AOB may have caused increased NOB abundance. The volumetric air supply as a proxy for O(2) supply thus needs to be linked to AOB activity. Further, NOB can be washed out of the system during regular operation if the system is operated at a sludge age in the range of 45 days and by controlling the air supply according to the NO(3)(-) concentration in the treated effluent. Early detection of growing NOB abundance while the population is still low can help guide process operation and it is suggested that molecular methods of quantifying NOB abundance should be tested.     

The influence of hydrophobic substances on water vapor permeability of fish gelatin films modified with transglutaminase or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)

The effect of different hydrophobic substances on water vapor permeability (WVP) of unmodified fish gelatin films and cross-linked with transglutaminase (TGase) or with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) was determined. Both unmodified and cross-linked films were characterized by very poor water barrier properties. Amaranth oil, rapeseed oil, lanolin, beeswax and ozococerite at concentration of 10% decreased WVP of unmodified gelatin films by 42, 15, 37, 53 and 36%, respectively. Increasing concentration of these substances up to 60% caused further improving of the water barrier properties. Addition of lecithin into film-forming emulsions prevented separation of lipid layer on the film surface. Among unmodified films with lecithin and 60% of lipids the highest decrease of WVP was found in case of amaranth oil and beeswax, by 73 and 87%, respectively, in comparison to only-gelatin films. WVP of chemically modified films in the presence of 60% of beeswax with addition of lecithin was decreased by about 65%. Enzymatically modified films with beeswax were very brittle and broke during analyzes, similarly as those with amaranth oil and lecithin. WVP of enzymatically modified films with lecithin and 60% of rapeseed oil and lanolin was respectively, about 60 and 47% lower than that of films without hydrophobic substances.     

Long chain polyunsaturated fatty acids in smoked Atlantic mackerel and Baltic sprats

Atlantic mackerel and Baltic sprats are rich sources of n − 3 long chain polyunsaturated fatty acids (LC PUFA). Literature data point to an influence of the properties of the raw material, storage conditions, and processing parameters of hot- and cold-smoking on the stability of these acids. The effects of industrial smoking in an automatic smokehouse in controlled, mild conditions at core temperature below 60 °C, as well as of cold storage, on the fatty acids (FA) in mackerel and sprats have been investigated. The FA were determined by gas chromatography (GC) according to the AOCS Ce 1b-89 method, in lipids extracted from the meat of several batches of defrosted and smoked fish early after smoking and during storage at 2 °C for up to 2 weeks. The contents of eicosapentaenoic acid C20:5 n − 3 (EPA) and docosahexaenoic acid C22:6 n − 3 (DHA) in different assortments of smoked mackerel meat were from 50 to 55 and from 67 to 100 mg/g of lipids, respectively while, in hot-smoked sprats, they were from 48 to 68 and from 73 to 128 mg/g of lipids. The results show that the variability of the FA composition of the frozen raw material was larger than the changes induced by smoking or by storage within the period of high quality life of the smoked product.     

Expanding an Efficient,Electrically Driven and CNT‐Tagged P450 System into the Third Dimension: A Nanowired CNT‐Containing and Enzyme‐Stabilising 3 D Sol–Gel Electrode

Although electrochemically catalysed P450 reactions have been described, their efficiency and applicability remained limited. This is mostly due to low enzyme activity, laborious protein immobilisation and the small electrode surface. We established a novel protein immobilisation method for a determined orientation and electrical wiring of the enzyme without post‐expression modification. By genetic introduction of an anchor‐peptide our method is applicable for screening medium to large mutant libraries and detection by an electrode system. The system was expanded by using wired carbon nanotubes within a sol‐gel matrix to create a three dimensional electrode.     

Influence of solution composition on sprayed ZnO nanorods properties and formation process: Thermoanalytical study of the precursors

ZnO is an important inorganic material for numerous applications. Different physical and chemical methods have been applied to deposit ZnO. Spray pyrolysis method being simple, rapid and low-cost is amongst the many options and has been chosen for this study. Fabrication of ZnO nanorods crystals by chemical spray pyrolysis was performed using an acidic solution of ZnCl₂1 or a basic ammonia-containing solution of ZnCl₂2. All layers were studied using X-ray diffractometry and Scanning Electron Microscopy. The formation of ZnO nanorods from 2 appeared at 450?°C, whereas spraying acidic solution 1 yielded ZnO nanorods like morphology at 550?°C.Thermal decomposition of precursors for ZnO layers prepared by de-watering of acidic aqueous solution of ZnCl₂ with pH =?3 (1) and basic solution of ZnCl₂ and NH₄OH with pH =?10 (2) was monitored by simultaneous thermogravimetric and differential thermal analysis (TG/DTA) in air coupled online with evolved gas analyses by Fourier transformed infrared spectroscopy (FTIR).The precursor (1) is ZnCl₂ *nH₂O; the precursor (2) is a mixture of (NH₄)₃(ZnCl₄)Cl, Zn(NH₃)₂Cl₂, NH₄Cl(NH₃)₃ and Zn(OH)₂ phases. The thermal decomposition of (1) and (2) in the temperature range of 30–700?°C consists of two steps with total mass losses of 86.2% and 93.8%, respectively. The main evolved gases from (1) are H₂O and HCl, whereas the main evolved gases from (2) are H₂O, NO_x and NH₃. Degradation of (1) and (2) is completed by 670 and 620?°C, respectively. The final decomposition product of (1) and (2) at 700?°C is ZnO.This study shows that the use of basic solutions enables to decrease the temperature of ZnO formation and the deposition temperature of ZnO nanorods layers.     

Densification of nanosized amorphous and crystalline silicon nitride powders

The hot-pressing behavior of two amorphous and three crystalline silicon nitride powders, including both experimental and commercial samples has been investigated in the presence of MgO-Y₂O₃ sintering aid. The powders were characterized in terms of bulk and surface chemistry, phase composition and morphology. The sintering behavior was assessed on the basis of green and final densities, weight loss on densification and chemical and phase compositions of the dense material. ©