New design of low power, 100 Mb-s IR-UWB pulse generator in 0.18 µm CMOS technology

A new method of impulse radio ultra-wideband (IR-UWB) pulse generation, with advantage of providing a “notch” like representation of pulse in the spectrum domain for particular control parameters values, is investigated in this paper. Low power pulse generator is composed of a glitch generator, a switched oscillator, a two-stage buffer and a pulse shaping filter. The proposed architecture, designed in UMC 0.18 µm CMOS technology, can operate in a single band from 3.3 GHz to 9.3 GHz or in a double, lower and higher UWB band (from 3 GHz to 9.15 GHz), suppressing frequencies in the WLAN band. Both spectrums fully comply with the corresponding FCC spectral mask, while the pulse generator regime and the spectrum range are determined by control signal values. Post-layout simulation results showed a pulse width of 0.5 ns, and a peak-to-peak amplitude of 211 mV for one band spectrum. The average power consumption is 0.89 mW corresponding to the energy consumption of 8.9 pJ/pulse for 100 MHz pulse repetition rate (PRF). The pulse duration is 1 ns and peak-to-peak amplitude is 202 mV in the case of the WLAN frequency band suppression. The total chip area is 0.31 mm². The pulse generator has been evaluated for the best performance supporting the on-off keying (OOK) modulation.     

Elemental Composition of Various Sour Cherry and Table Grape Cultivars Using Inductively Coupled Plasma Atomic Emission Spectrometry Method (ICP-OES)

Three sour cherry and three table grape cultivars were analyzed using inductively coupled plasma optical emission spectrometry. The elements: Na, K, Ca, Mg, Fe, Cu, Zn, Mn, Cr, Cd, Co, Pb, and Ni were detected in all samples; four elements are very abundant (K, Na, Ca, and Mg), and four are not abundant (Cu, Fe, Mn, and Zn). Five of them are trace elements (Cr, Cd, Co, Pb, and Ni) at <0.1 mg/kg. Among the 13 elements analyzed, potassium was the most abundant element distributed throughout all categories of fruits. Iron was the predominant minor element constituents. Manganese concentration was the highest in table grape cultivars. The accuracy of the results was evaluated by spike recovery tests. Analysis of variance was used to establish the metals with significant difference in mean content between the cultivars from sour cherries and between table grapes. Principal component analysis was used to evaluate the distribution of metals.     

Application of Twisselmann extraction, SPME, and GC-MS to assess input sources for organophosphate esters into soil

Although the ubiquitous distribution of organophosphate esters (OPEs) in the environment has been documented very thoroughly, data on their occurrence in soil is so far sparse. In this study, an analytical method was developed to determine six OPEs in soil. The method consists of a combination of Twisselmann extraction and solid-phase microextraction (SPME), followed by gas chromatography-mass spectrometry (GC-MS). To develop the method, spiked soil was extracted using a Twisselmann extractor after freeze-drying. The extract was evaporated to dryness, redissolved, and filtered. A volume of 7 mL was then analyzed by SPME, followed by GC-MS. The effects of different parameters on analyte recoveries during sample preparation, e.g., solvent for Twisselmann extraction, solvent for redissolving the extract, addition of copper, and filtration of the extract, were systematically investigated. Under optimum conditions, 10 g soil samples were extracted using toluene, and the extract was redissolved in methanol/water (1:14) and filtered. It was not necessary to add copper. For TnBP, TBEP, TCPP, and TCEP, recoveries ranged from 77.0% to 89.6%. Those for TPP and TDCP were much lower, at 31.5% and 42.0%, respectively (addition level 22.9-45.8 ng g(-1)). The variability of recoveries under these conditions was between 0.3 and 16.2% (n = 3). Limits of detection (LOD) were 0.002-3 ng g(-1). When ultrasonication was used in place of Twisselmann extraction in the developed method, recoveries were three to four times lower (27.4% to 30.6%), but the variability of recoveries was below 3% (n = 3). The method was applied to quantify OPEs in soil collected from the university campus in Osnabrueck (Germany). Average concentrations (n = 6) in soil samples ranged from 1.23 ng g(-1) to 4.96 ng g(-1) (dry weight) for TCPP, TPP, and TCEP. The results demonstrate for the first time that atmospheric deposition leads to soil contamination by OPEs.     

Determination of <Emphasis Type="Italic">Bacillus cereus</Emphasis> Emetic Toxin in Food Products by Means of LC–MS²

Cereulide is the heat-stable toxin produced by certain strains of Bacillus cereus. It is the main virulence factor of emetic B. cereus strains, which causes the emetic food poisoning syndrome, including rare fatal cases of food intoxications. Due to presumably low intoxication doses, a sensitive, specific, and robust technique is needed for its detection. In 2002, a LC–MS method was developed which allowed absolute quantification of cereulide using valinomycin as standard. This study describes the validation, according to the Commission Decision 2002/657/EC, of the LC–MS2 method, a tandem mass spectrometry technique, which guarantees lower detection limit and higher specificity. The LC–MS2 method, calibrated with valinomycin, was validated in rice and tested on various matrices (i.e., red beans, spices, and chili con carne) containing cereulide. The process combines a simple extraction step from the food matrix followed by LC–MS2 analysis and detection by ion trap mass spectrometer. The detection limit for cereulide in rice was 0.5 ng eq/g, which is 20 to 2,500 times lower than currently understood intoxicative doses between 10 and 1.280 ng/g previously reported for cereulide. The validated method was specific, sensitive, repeatable, and reproducible with recoveries ranging from 77% to 101%.     

Phenolic profile and antioxidant capacities of dried red currant from Serbia, extracted with different solvent

The antioxidant capacity and the phenolic content of 3 dried red currant samples from different geographical regions were studied. Three solvent systems were used (methanol, ethanol, and acetone) at the same concentrations (70%) and with 100% deionized water in presence 0.1% HCl. The antioxidant capacity of the dried fruit extracts was evaluated using DPPH radical scavenging assays. The efficiency of the solvents used to extract phenols from the 3 dried red currant samples varied considerably. The polyphenol content of the dried red currant samples was 3.26 to 12.68 mg gallic acid equivalent/g dried fruit. The high phenolic content was significantly correlated with the high antioxidant capacity. The following compounds were identified and quantified using HPLC with photodiode-array detection: 3 anthocyanins, 2 flavonols, 2 flavan-3-ols, and 3 hydroxycinnamic acids in all samples. Generally, red currant fruits are a rich source of phenolics, which shows an evident antioxidant capacity.     

Lignin Microspheres Modified with Magnetite Nanoparticles as a Selenate Highly Porous Adsorbent

Highly porous lignin-based microspheres, modified by magnetite nanoparticles, were used for the first time for the removal of selenate anions, Se(VI), from spiked and real water samples. The influence of experimental conditions: selenate concentration, adsorbent dosage and contact time on the adsorption capacity was investigated in a batch experimental mode. The FTIR, XRD, SEM techniques were used to analyze the structural and morphological properties of the native and exhausted adsorbent. The maximum adsorption capacity was found to be 69.9 mg/g for Se(VI) anions at pH 6.46 from the simulated water samples. The modified natural polymer was efficient in Se(VI) removal from the real (potable) water samples, originated from six cities in the Republic of Serbia, with an overage efficacy of 20%. The regeneration capacity of 61% in one cycle of desorption (0.5 M NaOH as desorption solution) of bio-based adsorbent was gained in this investigation. The examined material demonstrated a significant affinity for Se(VI) oxyanion, but a low potential for multi-cycle material application; consequently, the loaded sorbent could be proposed to be used as a Se fertilizer.     

Protein profiles and total antioxidant capacity of water‐soluble and water‐insoluble fractions of white brined goat cheese at different stages of ripening

This study deals with proteolysis and total antioxidant capacity of proteins of white brined cheese prepared from overheated goat milk and ripened for fifty days. Proteolytic changes were reflected through the relatively low level of soluble nitrogen (50 days ripened cheese had 15.32 g/100 g of water‐soluble nitrogen, 8.1 g/100 g of TCA‐soluble nitrogen and 2.69 g/100 g of PTA‐SN), intensive proteolysis of α_s2‐CN during initial 10 days of ripening (up to 50.70% of initial content) and its much slower degradation through further 40 days, slow but continual decrease of β‐CN content (up to 85.14% of residual content) and high level of proteolytic products tightly bounded into gel network. Total antioxidant capacity of water‐soluble and water‐insoluble fractions increased after cheese ripening. These findings could be useful for better understanding and control over the production of white brined goat cheese as highly valuable functional product.