Baseline Peaks Research Articles

Empirical evaluation of energy profiles of thermally-efficient homes with smart energy systems and controls

Smart control technologies are beginning to be deployed in homes to optimise heating and alter the timing of domestic energy demand to enable residential demand side response (DSR). This paper presents before (baseline phase) and after (control phase) evaluation of the monitored indoor temperature and energy demand during the heating season in 10 new-build dwellings, each of which received a 5kWh electro-chemical battery and smart control to enable shifting of heating energy demand. The dwellings had air source heat pumps (ASHP) and 2kWp solar photovoltaic (PV) panels, and were located in a social housing estate in Barnsley, England. For eight dwellings, heat pump electricity use per heating degree day was found to decrease by 10% and narrow baseline peaks were suppressed during the control phase. Daily mean grid electricity import and heat pump electricity use in the peak period (4pm – 7pm) were measured as 4.0 kWh and 1.4 kWh during the control phase as compared to 3.8kWh and 1.3 kWh for the baseline phase. However the use of a flat tariff (single-rate) meant that battery charging-discharging capability was not fully utilised. Time-of-use tariff would further enhance cost savings associated with the change in the timing of energy demand.

Protein Engineering of Mung Bean (Vigna radiata (L.) Wilczek) 8Sα Globulin with Lactostatin

Mung bean is a well-known good source of protein. To increase its bioactivity, economic value, and nutritional content as a functional food and food additive, lactostatin (IIAEK), a cholesterol-lowering bioactive peptide, was engineered into mung bean 8Sα globulin, a major storage protein. The results showed that the mutated 8Sα globulin has a significant bile acid binding capacity (cholesterol-lowering activity) up to 47.25%. Moreover, superimposed mutant (Mut2) and wild-type (Wt) 3D protein structures showed a 93–97% identity, indicating that the mutant proteins are stable. Ultra-performance liquid chromatography(UPLC)-based assay showed similar retention time for wild-type and mutant protein samples. Both IIAEK peptide standard and Mut2 digest had comparable baseline peaks corresponding to the same molecular size based on the liquid chromatography-mass spectrometry (LC-MS) data. A 573.36-Da mass spectrum was seen in Mut2, which indicates that Mut2 8Sα globulin has been successfully mutated and digested to release the bioactive peptide, IIAEK. In vitro bile acid binding capacity showed that the 6-h Wt and 12-h engineered protein (Mut2) digests had the highest activity. Lastly, potential allergenicity was checked in the Allergen Database for Food Safety (ADFS) and the AllerBase database, and the IIAEK peptide matched the Bos d 5 epitopes. This study provides a strong foundation and basis for mung bean nutrition improvement, development of cholesterol-lowering food supplements, and protein engineering of other food proteins.

Non‐invasive quality analysis of thawed tuna using near infrared spectroscopy with baseline correction

AbstractIn order to investigate the ability of NIR spectroscopy coupled with baseline correction to detect quality‐related changes of thawed tuna during the storage and the transportation. First, adaptive iteratively reweighted penalized least squares (airPLS) method was taken to eliminate the baseline and estimate spectra feature peaks of 168 samples (bigeye = 82, yellowfin = 86), and the Monte Carlo method was used to determine the optimal adjustment parameter λ. Second, predictive models based on the fitted features were established by the partial least squares regression (PLSR) to estimate docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), fat, and protein content. Compared with the standard normal variate (SNV), the proposed airPLS achieved good performance in a comparative experimental test. When the original spectra was preprocessed by airPLS, the number of feature peaks (nf) and the mean value of R2 () achieved 6 and 0.89 respectively, which is greater than that of the preprocessing algorithm SNV (nf = 4 and ). The proposed airPLS effectively reduces the interfering variability and reserves much more NIR features, which is a feasible and stable method for quality‐related analysis of the thawed tuna.Practical application: During the storage and the transportation, the rich nutrients in tuna are easily oxidized and degraded when they are exposed to the air. In order to develop effective methods to determine the quality of tuna and avoid selling thawed products as the fresh tuna, a quality‐related analysis method for thawed tuna based on the baseline correction is proposed to improve the prediction accuracy.

Impact of Soil Water on the Spectral Characteristics and Accuracy of Energy-Dispersive X-ray Fluorescence Measurement.

Soil water is a major interference in the on-site analysis of soil by energy-dispersive X-ray fluorescence. Apparent consequences of this interference include lowered readings for elemental concentrations and significant changes in spectral characteristics in wet soils compared with dry soils. A rigorous interpretation on this issue remains unresolved. Thus, this study evaluated the impact of soil water on the detection of Ca, Ti, Mn, Fe, Cu, Zn, As, Rb, Sr, and Pb. Specimens were prepared from 11 certified reference soils and 3 field soils with water contents from 0 to ∼40 wt %. Results from three commercial models revealed that the readings were subjected to respective internal quantification algorithms; therefore, they could not provide a fundamental perspective of this issue. We analyzed the spectra to examine the mechanism underlying this phenomenon. The spectra of wet soils feature elevated baseline, increased Compton and Rayleigh scatter peaks, and lowered characteristic peaks of elements. Previous studies attributed the lowered characteristic peaks to the absorption of fluorescent X-rays by water and considered soil water and dry soil as separate layers in the calculation. This work argues that wet soils should be treated as mixtures. Water becomes part of the soil matrix and leads to lower attenuation capability, which could be explained by the matrix effect. Meanwhile, the mass fraction of analytes is lowered because of dilution. Results confirmed that dilution lowers the characteristic peaks, whereas the matrix effect heightens them. When estimating the elemental concentrations on a wet weight basis, the matrix effect becomes the major interference. The Compton compensation method provided satisfying results on correcting the matrix effect caused by soil water on Zn, As, Rb, Sr, and Pb.

Linear MALDI-ToF simultaneous spectrum deconvolution and baseline removal

BackgroundThanks to a reasonable cost and simple sample preparation procedure, linear MALDI-ToF spectrometry is a growing technology for clinical microbiology. With appropriate spectrum databases, this technology can be used for early identification of pathogens in body fluids. However, due to the low resolution of linear MALDI-ToF instruments, robust and accurate peak picking remains a challenging task. In this context we propose a new peak extraction algorithm from raw spectrum. With this method the spectrum baseline and spectrum peaks are processed jointly. The approach relies on an additive model constituted by a smooth baseline part plus a sparse peak list convolved with a known peak shape. The model is then fitted under a Gaussian noise model. The proposed method is well suited to process low resolution spectra with important baseline and unresolved peaks.ResultsWe developed a new peak deconvolution procedure. The paper describes the method derivation and discusses some of its interpretations. The algorithm is then described in a pseudo-code form where the required optimization procedure is detailed. For synthetic data the method is compared to a more conventional approach. The new method reduces artifacts caused by the usual two-steps procedure, baseline removal then peak extraction. Finally some results on real linear MALDI-ToF spectra are provided.ConclusionsWe introduced a new method for peak picking, where peak deconvolution and baseline computation are performed jointly. On simulated data we showed that this global approach performs better than a classical one where baseline and peaks are processed sequentially. A dedicated experiment has been conducted on real spectra. In this study a collection of spectra of spiked proteins were acquired and then analyzed. Better performances of the proposed method, in term of accuracy and reproductibility, have been observed and validated by an extended statistical analysis.

Instant detection and identification of concealed explosive-related compounds: Induced Stokes Raman versus infrared

The instant detection of explosives and explosive-related compounds has become an urgent priority in recent years for homeland security and counter-terrorism applications. Modern techniques should offer enhancement in selectivity, sensitivity, and standoff distances. Miniaturisation, portability, and field-ruggedisation are crucial requirements. This study reports on instant and standoff identification of concealed explosive-related compounds using customized Raman technique. Stokes Raman spectra of common explosive-related compounds were generated and spectrally resolved to create characteristic finger print spectra. The scattered Raman emissions over the band 400:2000cm−1 were compared to infrared absorption using FTIR. It has been demonstrated that the two vibrational spectroscopic techniques were opposite and completing each other. Molecular vibrations with strong absorption in infrared (those involve strong change in dipole moments) induced weak signals in Raman and vice versa. The tailored Raman offered instant detection, high sensitivity, and standoff detection capabilities. Raman demonstrated characteristic fingerprint spectra with stable baseline and sharp intense peaks. Complete correlations of absorption/scattered signals to certain molecular vibrations were conducted to generate an entire spectroscopic profile of explosive-related compounds. This manuscript shades the light on Raman as one of the prevailing technologies for instantaneous detection of explosive-related compounds.

Monte Carlo point process estimation of electromyographic envelopes from motor cortical spikes for brain–machine interfaces

Objective. Representation of movement in the motor cortex (M1) has been widely studied in brain–machine interfaces (BMIs). The electromyogram (EMG) has greater bandwidth than the conventional kinematic variables (such as position, velocity), and is functionally related to the discharge of cortical neurons. As the stochastic information of EMG is derived from the explicit spike time structure, point process (PP) methods will be a good solution for decoding EMG directly from neural spike trains. Previous studies usually assume linear or exponential tuning curves between neural firing and EMG, which may not be true. Approach. In our analysis, we estimate the tuning curves in a data-driven way and find both the traditional functional-excitatory and functional-inhibitory neurons, which are widely found across a rat’s motor cortex. To accurately decode EMG envelopes from M1 neural spike trains, the Monte Carlo point process (MCPP) method is implemented based on such nonlinear tuning properties. Main results. Better reconstruction of EMG signals is shown on baseline and extreme high peaks, as our method can better preserve the nonlinearity of the neural tuning during decoding. The MCPP improves the prediction accuracy (the normalized mean squared error) 57% and 66% on average compared with the adaptive point process filter using linear and exponential tuning curves respectively, for all 112 data segments across six rats. Compared to a Wiener filter using spike rates with an optimal window size of 50 ms, MCPP decoding EMG from a point process improves the normalized mean square error (NMSE) by 59% on average. Significance. These results suggest that neural tuning is constantly changing during task execution and therefore, the use of spike timing methodologies and estimation of appropriate tuning curves needs to be undertaken for better EMG decoding in motor BMIs.

Toxicological screening of human plasma by on-line SPE-HPLC-DAD: identification and quantification of acidic and neutral drugs.

A multi-analyte screening method for the quantification of 50 acidic/neutral drugs in human plasma based on on-line solid-phase extraction (SPE)-HPLC with photodiode array detection (DAD) was developed, validated and applied for clinical investigation. Acetone and methanol for protein precipitation, three different SPE materials (two electro-neutral, one strong anion-exchange, one weak cation-exchange) for on-line extraction, five HPLC-columns [one C18 (GeminiNX), two phenyl-hexyl (Gemini C6 -Phenyl, Kinetex Phenyl-Hexyl) and two pentafluorophenyl (LunaPFP(2), KinetexPFP)] for analytical separation were tested. For sample pre-treatment, acetone in the ratio 1:2 (plasma:acetone) showed a better baseline and fewer matrix peaks in the chromatogram than methanol. Only the strong anion-exchanger SPE cartridge (StrataX-A, pH 6) allowed the extraction of salicylic acid. Analytical separation was carried out on a Gemini C6 -Phenyl column (150 × 4.6 mm, 3 µm) using gradient elution with acetonitrile-water 90:10 (v/v) and phosphate buffer (pH 2.3). Linear calibration curves with correlation coefficients r ≥ 0.9950/0.9910 were obtained for 46/four analytes. Additionally, this method allows the quantification of 23 analytes for therapeutic drug monitoring. Limits of quantitation ranged from 0.1 (amobarbital) to 23 mg/L (salicylic acid). Inter-/intra-day precisions of quality control samples (low/high) were better than 13% and accuracy (bias) ranged from -14 to 10%. A computer-assisted database was created for automated detection of 223 analytes of toxicological interests. Four cases of multi-drug intoxications are presented.

Center of Gravity (COG) Method as a Tool in Processing of Voltammetric Signals

AbstractThe center of gravity method (COG) was applied (for the first time) in voltammetry (polarography) as a tool for very precise determination of peak potentials, and signal shifts. Basically, the adjustment of the method consists of finding the optimal fraction of the peak that contains information about peak position, either of original signal or of its 1st or 2nd derivatives, along with optimal selection of parameters for SavitzkyGolay smoothing of original curves and elimination of baseline influence. The principle of the method and its validation were demonstrated and checked on simulated differential pulse polarograms (DPP) representing a series of curves for the determination of stability constants of labile metal complexes (DeFord‐Hume method). It was shown that COG outperforms the classical “one‐point” method (OPM) in precision and accuracy, providing excellent results even if a very large step potential (e.g. 10 mV) was used. The problems of reduced accuracy and precision in case of curved (non‐ideal) baseline and asymmetric peaks were successfully overcome by applying COG on curves transformed by 1st and/or 2nd derivatives. The method was additionally examined in details on a simple experimental dataset of cadmium chloride complexes in 4 mol dm−3 ionic strength solution and on a more complex dataset of uranyl selenate complexes in 3 mol dm−3 ionic strength solution. Stability constants obtained by COG agree well with those in the literature with much better precision than the classical one‐point method (checked by standard error of the fit).

Reproducibility of the water drinking test in treated glaucomatous patients.

To evaluate the reproducibility of intraocular pressure peaks and fluctuation elicited during the water drinking test in treated glaucomatous patients with a long follow-up interval. Retrospective cohort study in a tertiary care practice. Thirty-four treated primary open-angle glaucoma patients. All patients underwent the water drinking test performed in two consecutive visits without any change in the therapeutic regimen. The mean interval between tests was 4.85 (range: 3-6) months. Reproducibility of peak and fluctuation during the water drinking test was assessed using intraclass correlation coefficients. Bland-Altman analysis was used to assess the agreement of intraocular pressure peaks and fluctuation measured between two consecutive tests. Intraclass correlation and agreement of intraocular pressure peaks and fluctuation between visits. There were no significant differences in baseline intraocular pressure values (mean ± standard deviation, 11.73 ± 2.36 and 11.61 ± 2.71 mmHg; P = 0.72) and peaks (14.55 ± 3.41 and 15.02 ± 3.66 mmHg, respectively; P = 0.163) detected during the water drinking test between the first and second visits. There was also no significant difference between the average intraocular pressure fluctuation values (2.82 ± 1.99 and 3.41 ± 2.54 mmHg, respectively; P = 0.135). Intraocular pressure peaks and fluctuation presented intraclass correlation coefficients of 0.85 (P < 0.001) and 0.50 (P < 0.001), respectively. Our results demonstrate excellent reproducibility of intraocular pressure peaks during the water drinking test. Intraocular pressure fluctuation did not reveal good reproducibility, though. These results emphasize the applicability of this test to assess treatment efficacy in daily practice and interventional studies.

Comparison of supercritical fluid chromatography and reverse phase liquid chromatography for the impurity profiling of the antiretroviral drugs lamivudine/BMS-986001/efavirenz in a combination tablet

Dual and triple combinations of antiretroviral drugs are a cornerstone of human immunodeficiency virus type 1 (HIV-1) treatment. Supercritical fluid chromatography (SFC) and reverse phase liquid chromatography (RPLC) methods have been developed for the impurity profiling of a prototype combination tablet containing three such drugs: lamivudine, BMS-986001 and efavirenz. Separation by SFC was achieved using a Princeton 2-ethyl pyridine stationary phase and a mobile phase B consisting of methanol with 10mM ammonium acetate and 0.1% isopropyl amine. This combination of mobile phase additives was required for both the separation of minor components and to minimize peak tailing of the active pharmaceutical ingredients (APIs). Separation by RPLC was achieved using a Discovery HSF5 stationary phase and a mobile phase consisting of 10mM ammonium acetate, pH 5.5 and methanol. Mobile phase gradient elution was employed in each case to elute components with a wide range of polarities. Both these methods were found to have advantages and disadvantages. Out of the three APIs and 13 possible impurity/degradation products selected, all were resolved by RPLC. By SFC, 15 peaks were resolved with one co-eluting pair and a high degree of orthogonality was achieved relative to RPLC. A more even distribution of peaks across the separation space, a non-sloping baseline and fewer system peaks were significant advantages associated with the SFC method. Particular attention had to be paid to optimizing the reverse phase diluent strength/initial mobile phase composition to avoid distortion of the peak shapes for early eluting components. This was not an issue with SFC, as the diluent of choice (methanol) was also the solvent of choice (in combination with ≤20% water) for the dissolution of the triple combination tablet. As with RPLC, SFC was found to exhibit the required sensitivity for successful quantitation of potential impurities/degradation products at the 0.05–0.1 area% level.

A stereospecific high‐performance liquid chromatographic assay for the determination of ketoconazole enantiomers in rat plasma

A stereospecific high-performance liquid chromatographic assay was developed for the quantitation of ketoconazole enantiomers (KTZ) in rat plasma. After protein precipitation of 100 microL plasma using acetonitrile, a wash step was performed using hexane. The supernatant was removed and KTZ enantiomers and amiodarone, the internal standard, were extracted using liquid-liquid extraction with tert-butyl methyl ether. After transfer and evaporation of the organic layer, the residue was reconstituted in mobile phase and injected into the HPLC through a chiral column. The mobile phase consisted of hexane:ethanol:2-propanol with diethyl amine, pumped at 1.5 mL/min. All components eluted within 18 min. KTZ enantiomers were baseline resolved and peaks were symmetrical in appearance with no interferences. Calibration curves were linear over the range 62.5-5000 ng/mL of enantiomer. The intraday and interday CV% assessments were <or=19 and <13%, respectively, and mean error was <4% for both enantiomers. The lower limit of quantitation was 62.5 ng/mL for each enantiomer based on 100 microL rat plasma. In rats, plasma concentrations of (+)-KTZ were higher than those of antipode after single oral doses. The assay was shown to be sensitive and appropriate for use in pharmacokinetics study of KTZ in rat.

Determination of Fenofibric Acid Concentrations by HPLC After Anion Exchange Solid-Phase Extraction From Human Serum

Triglycerides are increasingly being recognized as a risk factor for cardiovascular disease. Research efforts to identify sources of variability in triglyceride-lowering response to the lipid-lowering drug fenofibrate require quantification of the active acidic form of this PPAR-alpha agonist. Anion-exchange solid-phase extraction, in combination with reverse-phase high-performance liquid chromatography (HPLC), rapidly and accurately determines steady-state fenofibric acid serum concentrations. Chromatographic separation under isocratic conditions, with use of ultraviolet detection at 285 nm, provides clean baseline and sharp peaks for clofibric acid, 1-napthyl acetic acid (internal standards), and fenofibric acid. Commonly prescribed and over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) were screened for assay interference, and the assay was employed to quantify fenofibric acid in more than 800 human subject specimens. Fenofibric acid analysis was found to be linear over the range of 0.5 to 40 mg/L and was validated with either internal standard. Accuracies ranged from 98.65% to 102.4%, whereas the within- and between-day precisions ranged from 1.0% to 2.2% and 2.0% to 6.2%, respectively. NSAIDs had minimal interference with the assay, which succeeded in quantifying fenofibric acid in more than 843 of 846 serum samples from human subjects, many taking a variety of coadministered medications. Anion-exchange solid-phase extraction in combination with reverse-phase HPLC accurately determines steady-state fenofibric acid serum concentrations in humans without interference from NSAIDs or commonly administered medications. This method is suitable for quantification of fenofibric acid for clinical pharmacokinetic studies in patients with dyslipidemia.

Phase I clinical and pharmacological trial of trabectedin (T) in 3 hour infusion every 3 weeks (3h/q3w) in patients with advanced cancer and hepatic function disorder

2080 Background: Trabectedin (ET-743) is a marine-derived DNA and transcription interacting agent with activity in pretreated soft tissue sarcoma, breast, prostate and ovarian cancer. T is associated with 2 types of liver function alterations: a frequent acute and reversible elevation of ALT and AST and a less frequent cholestasis, usually reflected by low grade increases in alkaline phosphatase (AP) and bilirubin (B). The main predictors of dose limiting toxicity (DLT) or T-related serious adverse events appear to include elevated baseline or intercycle peaks of AP, B and ALT &gt; 5 × ULN (Gomez J, ASCO 2000). The objectives of this trial are to determine the maximum tolerated dose (MTD) and pharmacokinetics (PK) of T 3h/q3w in patients (pts) with advanced cancer and baseline liver dysfunction. Methods: All pts are stratified according to basal liver function as follows: STRATUM (S) I: ULN &lt; AP ≤ 1.5 × ULN S II: 1.5 × ULN &lt; AP ≤ 2.5 × ULN S III: AP &gt; 2.5 × ULN All pts had to have AST and ALT ≤ 2.5 × ULN, albumin &gt; 2.5 g/dl and B &lt; 2.5 mg/dl. T concentrations in plasma are determined using a validated LC-MS/MS method. PK parameters were calculated by non-compartmental methods. Results: 32 pts were recruited.Median age: 54 years (26–76); PS≤1:28 pts; prior chemotherapy (CT): 31 pts (97%); median number of prior CT: 2 (1–6); B &gt; ULN: 0 pts. In S I, T was administered at 1.1 mg/m2 (3 pts) and 1.3 mg/m2 (13 pts). Two DLTs were reported at 1.3 mg/m2: neutropenia G4 &gt; 5 days with febrile neutropenia and G3 ALT not recovered by day +28. In S II no DLT occurred in 4 pts at T 0.9 mg/m2 nor 3 pts at T 1.1 mg/m2, 1 out of 4 pts at 1.3 mg/m2 suffered DLT: G3 AST not recovered by day +24. In S III one out of 2 pts at 0.9 mg/m2 had DLT: AP increase. Initial PK evaluation from S I and II (8 from each) showed a long half life (geometric mean (GM) S I: 124.6 h, S II: 118.8 h) and wide distribution (GM Vss S I: 2366 l/m2, S II: 3830 l/m2). GM clearance: 18.3 l/(hr*m2) in S I; 26.3 l/(hr*m2) in S II. Clearance is somewhat lower than in normal liver function population (GM under equal dexamethasone treatment 33.8 l/hr*m2) in study ET-B-010. Conclusions: The recommended dose (RD) of T for pts with mild AP elevations (&lt; 1.5 ULN) and B levels &lt; ULN is 1.3 mg/m2 3h/q3w. The study is ongoing to define the RD for S II and III [Table: see text]

Rapid Separation of Milk Whey Proteins by Anion Exchange Chromatography

A fast protein liquid chromatography system was used to fractionate the major proteins of sweet and acid wheys. Fifty to 500μl of whey were fractionated with a stepwise ionic strength gradient using water (buffer A) and increasing concentrations of .7 M sodium acetate (buffer B). Six well-resolved peaks were obtained: 1) amino acids (tentative identification), 2) low molecular weight peptides (tentative identification), 3) highly enriched α-lactalbumin, 4) highly enriched serum albumin 5) electrophoretically pure β-lactoglobulin B, and electrophoretically pure β-lactoglobulin A. A poor baseline or unresolved peaks resulted when .02 M bis-tris or .02 M histidine was used for buffer A and .7 M sodium acetate in .02 M bis-tris or histidine was used for buffer B. When sodium chloride was used in place of sodium acetate, β-lactoglobulins A and B were poorly resolved. The column was cleaned after each run by injecting 2ml of the following reagents: glacial acetic acid, 2N sodium chloride, 2N sodium hydroxide, 2N sodium chloride, 2% detergent, and 100% acetonitrile. Time required to run each sample including column cleanup was 40min.