Fluoride Plasma Research Articles

Ab-initio study of [formula omitted] molecule adsorption on Si(001)-p(2 × 2) reconstructed surface

First-principles calculations are performed to investigate the relaxation and electronic properties of SiF2 molecule deposited on surface. The reconstructed Si(001)-p(2 × 2) surface, modeled using density functional theory method, forms the basis for our molecule adsorption study. Several adsorption configurations corresponding to different orientations of the molecule have been investigated. Both stable dissociative and non-dissociative adsorption are found. For the most stable configuration, the adsorption takes place without dissociation of the molecule whose silicon atom binds two atoms of the surface. The progressive decomposition process of SiF2 is also explored using the nudged elastic band (NEB) method. An important energy barrier is obtained for the SiF2 molecule decomposition as compared to that of the SiF molecule. This could explain the high percentage of the SiF2 volatile molecule observed experimentally during the fluoride plasma etching process on the Si(001) surface.

Heparin/polyethyleneimine dual-sided functional polyvinylidene fluoride plasma separation membrane for bilirubin removal

Herein, a novel heparin/polyethyleneimine (PEI) dual-sided functional polyvinylidene fluoride (PVDF) plasma separation membrane structure is proposed. Bilirubin is removed using this membrane via one-step “anticoagulation-adsorption”. When blood flows in the membrane, the inner side of the membrane can prolong clotting time. Meanwhile, bilirubin contained in plasma is filtrated through the membrane. Bilirubin is adsorbed on the outer side of the membrane to be removed. Herein, branched PEI was grafted on the outer side of the PVDF plasma separation membrane to construct the bilirubin adsorption functional layer. Then, heparin was grafted on the inner side to construct a self-anticoagulant functional layer. The dual-sided functional PVDF plasma separation membrane was prepared. The results showed that PEI and heparin could be grafted on the outer side and the inner side of the PVDF plasma separation membrane, separately. Bilirubin's competitive adsorption property of the outer side of the membrane was enhanced. Hemocompatibility of the inner side of the membrane was strengthened. The plasma permeability of the novel membrane gradually decreased to 250 L·m−2·h−1bar−1. The total plasma protein sieving coefficient of the novel membrane was larger than 80 %. Total bilirubin and direct bilirubin adsorption capacity reached 22.5 mg/g and 20.5 mg/g via one-step “anticoagulation-adsorption”. The novel membrane prepared in this work can effectively simplify traditional hemoperfusion therapy, implying its great potential application.

HOMA-IR and HOMA2-IR estimation based on glycated hemoglobin as an alternative for fasting glucose

ABSTRACT Background Diabetes mellitus is a major global public health problem. Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) is a key laboratory index in the assessment of insulin resistance. The calculation of HOMA-IR and its updated version HOMA2-IR are partly based on plasma glucose determinations, which are prone to important pre-analytical errors. As glycated hemoglobin (Hb) fractions strongly correlate with fasting glucose levels and are more stable analytes, we explored the possibilities of using glycated Hb fractions for calculating HOMA-IR. Methods Labile Hb and HbA1c fractions were simultaneously assayed on a Tosoh G8 analyzer and expressed as %. Fasting glucose was measured in fluoride plasma using a hexokinase method. A Lumipulse G1200 luminescence immunoassay was used to measure serum insulin. The HOMA-IR and HOMA2-IR values were compared to corresponding indices calculated using glucose and glycated Hb fractions. Results Labile Hb could be measured with between-run CVs of 2.2–2.3%. Labile Hb correlated with both glycemia (r = 0.80) and HbA1c results (r = 0.73). HbA1c-derived estimated average glucose (eAG)-based HOMA calculation correlated very well with HOMA-IR (r2 = 0.9972). Based on eAG calculations, HOMA2-IR (%B, %S, and IR) gave comparable results, as compared to labile Hb-based calculations, in particular for fasting plasma glucose values between 4.44 and 6.67 mmol/L. Conclusions HbA1c and eAG are practical alternatives for glucose for estimating HOMA-IR. The use of glycated Hb enables home sampling for HOMA-IR and HOMA2-IR calculation.

The facile method developed for preparing polyvinylidene fluoride plasma separation membrane via macromolecular interaction

The design of membrane pore is critical for membrane preparation. Polyvinylidene fluoride (PVDF) membrane exhibits outstanding properties in the water-treatment field. However, it is a huge challenge to prepare PVDF macro-pore plasma separation membrane by non-solvent induced phase separation (NIPS). Herein, a facile strategy is proposed to prepare PVDF macro-pore plasma separation membrane via macromolecular interaction. ATR-FTIR and 1 H NMR showed that the intermolecular interaction existed between polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP). It could significantly affect the PVDF macro-pore membrane structure. The maximum pore of the PVDF membrane could be effectively adjusted from small-pore/medium-pore to macro-pore by changing the molecular weight of PEO. The PVDF macro-pore membrane was obtained successfully when PEO-200 k existed with PVP. It exhibited higher plasma separation properties than the currently used plasma separation membrane. Moreover, it had excellent hemocompatibility due to the similar plasma effect, hemolysis, prothrombin time, blood effect and complement C 3a effect with the current utilized plasma separation membrane, implying its great potential application. The proposed facile strategy in this work provides a new method to prepare PVDF macro-pore plasma separation membrane by NIPS.

A Comparison of Serum and Plasma Blood Collection Tubes for the Integration of Epidemiological and Metabolomics Data

Blood is a rich biological sample routinely collected in clinical and epidemiological studies. With advancements in high throughput -omics technology, such as metabolomics, epidemiology can now delve more deeply and comprehensively into biological mechanisms involved in the etiology of diseases. However, the impact of the blood collection tube matrix of samples collected needs to be carefully considered to obtain meaningful biological interpretations and understand how the metabolite signatures are affected by different tube types. In the present study, we investigated whether the metabolic profile of blood collected as serum differed from samples collected as ACD plasma, citrate plasma, EDTA plasma, fluoride plasma, or heparin plasma. We identified and quantified 50 metabolites present in all samples utilizing nuclear magnetic resonance (NMR) spectroscopy. The heparin plasma tubes performed the closest to serum, with only three metabolites showing significant differences, followed by EDTA which significantly differed for five metabolites, and fluoride tubes which differed in eleven of the fifty metabolites. Most of these metabolite differences were due to higher levels of amino acids in serum compared to heparin plasma, EDTA plasma, and fluoride plasma. In contrast, metabolite measurements from ACD and citrate plasma differed significantly for approximately half of the metabolites assessed. These metabolite differences in ACD and citrate plasma were largely due to significant interfering peaks from the anticoagulants themselves. Blood is one of the most banked samples and thus mining and comparing samples between studies requires understanding how the metabolite signature is affected by the different media and different tube types.

Porous silicon - calcium fluoride plasma waveguide with asymmetric Ag film and its sensitivity characteristics

In this paper, a porous silicon-calcium fluoride hybrid plasmonic waveguide (PS-CaF<sub>2</sub> HPW) with an asymmetric silver film is studied. The PS-CaF<sub>2</sub> HPW is composed of a PS strip waveguide deposited with asymmetric CaF<sub>2</sub> and Ag thin film layers on an SiO<sub>2</sub> substrate. In the mid-infrared (MIR) region, the mode characteristics and waveguide sensitivity of the mode in the PS-CaF<sub>2</sub> HPW are simulated by using the finite element method (FEM). The results show that there are two fundamental modes (PM 1 and PM 2) with different polarization states in the PS-CaF<sub>2</sub> HPW. The real part of the effective refractive index (Re(<i>n</i><i><sub>eff</sub></i><italic/>)), transmission loss (<i>α</i>), normalized effective mode field area (<i>A</i>), quality factor (<i>FOM</i>) and sensitivity (<i>S</i><sub>wg</sub>) for each of the PM 1 and the PM 2 are studied and optimized. Moreover, the effect of temperature on the performances of the PS-CaF<sub>2</sub> HPW is also analyzed. Firstly, the mode field distributions calculated by the FEM indicate that the mode field energy for each of the PM 1 and PM 2 in the PS-CaF<sub>2</sub> HPW is mostly restricted to the PS layer and CaF<sub>2</sub> layer. Comparing with conventional dielectric waveguides, the mode field energy of the PS-CaF<sub>2</sub> HPW is well confined in the PS layer and CaF<sub>2</sub> layer. The geometric parameters of the PS-CaF<sub>2</sub> HPW are optimized by changing the geometric parameters (<i>W</i><sub>1</sub>, <i>W</i><sub>2</sub>, and <i>W</i><sub>3</sub>). When <i>W</i><sub>1</sub> = 1500 nm, <i>W</i><sub>2</sub> = 300 nm, <i>W</i><sub>3</sub> = 70 nm, and the operating wavelength is ~3.5 μm, <i>α</i> and <i>FOM</i> are 0.019 dB/μm and 1594.99 for the PM 1, and <i>α</i> and FOM are 0.016 dB/μm and 1335.54 for the PM 2, respectively. Secondly, the waveguide sensitivity of the PS-CaF<sub>2</sub> HPW is analyzed. The results show that the size of PS layer has a great influence on the waveguide sensitivity. The waveguide sensitivity decreases with the size of the PS layer increasing. In addition, the PS-CaF<sub>2</sub> HPW has good temperature resistance. Moreover, temperature has almost no effect on Re(<i>n</i><i><sub>eff</sub></i><italic/>), nor <i>α</i> nor <i>A</i> nor FOM nor <i>S</i><sub>wg</sub> in a temperature range from -40 K to 40 K. Finally, the fabrication tolerances of the PS-CaF<sub>2</sub> HPW are demonstrated, and the good properties are maintained in a size tolerance range from -10 nm to 10 nm. With the advantages in propagation property and loss reduction, the PS-CaF<sub>2</sub> HPW provides a feasible label-free biochemical sensing scheme and a method of polarization control devices.

A study on the assessment of stability of glucose concentrations in serum separator gel tubes

A study on the assessment of stability of glucose concentrations in serum separator gel tubes - IJCBR- Print ISSN No: - 2394-6369 Online ISSN No:- 2394-6377 Article DOI No:- 10.18231/2394-6377.2018.0069, International Journal of Clinical Biochemistry and Research-Int J Clin Biochem Res

Application of the atomic layer etching technique for the formation of SiC-based field emitters

This paper presents the technology of obtaining graphene films on the surface of SiC using a combination of methods of focused ion beams and plasma-chemical etching in a fluorine containing environment. For the formation of nanoscale structures with lateral dimensions of 280 nm, the method of focused ion beams was used. Nano sized structures were formed on the surface of silicon carbide by an ion beam, which were subsequently placed in the reactor. In the reactor, the structures on silicon carbide were processed in fluoride plasma. The depth of the structures was 900 nm. SF6 was used for atomic layer etching operations. The study of the surface topology at each iteration was carried out using scanning electron microscopy. Electrical characteristics were measured by atomic force microscopy.

Skeletal fluorosis after prolonged voriconazole therapy.

A 6-year-old girl underwent allogeneic hematopoietic stem cell transplantation for a relapsing acute myelogenous leukemia. She developed severe chronic graft-versus-host disease which required immunosuppressive therapies, including a prolonged course of high-dose steroids. She also presented a thrombotic microangiopathy complicated by renal failure requiring dialysis. Eleven months after transplantation, she was diagnosed with pulmonary and cerebral aspergillosis, prompting initiation of intravenous voriconazole. Unusually high doses were needed (11 mg/kg/dose every 8 hours) in order to achieve therapeutic plasmatic trough concentrations above 1 to 2 mg/L. After 2 months, she was transitioned to oral voriconazole at equivalent dosing. Six months after being on oral voriconazole, she complained of fatigue and diffuse musculoskeletal pain, initially attributed to her steroid treatment. Radiographs (Figure 1) of her femurs showed diffuse osteopenia and pronounced bilateral periosteal reactions with exostosis (arrows). ... The diagnosis of osseous fluorosis induced by prolonged voriconazole therapy was suspected and confirmed by a very high fluoride plasma concentration of 27.0 µmol/L (0.25 to 1.0 µmol/L). Her alkaline phosphatase level was also increased at 627 U/L (134 to 518 U/L), with a known normal baseline level preceding therapy. Voriconazole was discontinued and oral posaconazole was substituted in its place. Five months after voriconazole discontinuation, her musculoskeletal symptoms resolved and her fluoride plasma concentration decreased to 1.30 µg/mL.

Effect of border traps on the threshold voltage instability of fluoride-doped AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors

In this paper, we performed a systematic investigation of the threshold-voltage (Vth) instability of enhancement-mode (E-mode) AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs). The E-mode MIS-HEMTs are firstly demonstrated by using the fluoride plasma treatment and the Vth is characterized by 1.55 V after the 400 °C post-metallization annealing (PMA). This PMA which is used to eliminate the interface trap induced by the plasma damage exhibits a trade-off between the negative shift of Vth and the performance improvement both for the ON- and OFF-states. Nevertheless, a significant hysteresis occurs even after employing the PMA indicating that either interface traps or border traps in the insulator tend to capture the electrons, wherefore the traps result in a negative net charge. According to this result, both pulsed measurement and stress measurement with DC measurement are implemented to identify the property of the trap state. A significantly positive Vth shift is observed both in a long pulsed-width measurement and DC measurement right after the positive gate stress which implies that border traps with a long emission time constant induce a retentive Vth even under the DC measurement. Besides, compared to the fluoride-doped HEMT (i.e. HEMT without insulator insertion), fluoride-doped MIS-HEMT exhibiting a more significant Vth shift suggest that additional border traps are created through the fluoride ion diffusion during the high temperature annealing.

Efeitos de dois protocolos de sedação sobre as variáveis bioquímicas em gatos

RESUMO A utilização de protocolos de sedação como auxílio na contenção de felinos para realização de coletas de sangue é de grande importância, porém a utilização de alguns fármacos pode alterar resultados e a interpretação deles. Por outro lado, a contenção física pode gerar intenso estresse, especialmente em felinos, o que também pode interferir nos resultados. Este estudo teve como objetivo avaliar exames de bioquímica clínica sob o uso de contenção física e química em gatos submetidos a dois protocolos de sedação. Foram utilizados 50 gatos, 26 fêmeas e 24 machos, sem raça definida, submetidos a contenção física e, imediatamente após, a dois protocolos de sedação, DB (dexmedetomidina 5µg/kg e butorfanol 0,3mg/kg) e DBC (dexmedetomidina 5µg/kg, butorfanol 0,3mg/kg e cetamina 3mg/kg), aplicados por via intramuscular. Amostras de sangue foram coletadas após a contenção física e, em seguida, após o uso de um dos protocolos de sedação. Foram avaliados: ureia, creatinina, alaninoaminotransferase (ALT), fosfatase alcalina, proteína sérica total (PST), albumina, globulinas, colesterol, triglicérides, cálcio, magnésio e cloretos de amostras de soro, lactato e glicose de amostras de plasma fluoretado. Foi encontrada diferença estatística entre grupos para albumina, triglicérides, PST e colesterol, com maiores valores sendo encontrados no grupo DBC. Entre momentos, houve diferença para colesterol e fosfatase alcalina, com maiores valores no momento contenção física somente no grupo DBC. Já a glicose teve maiores valores após a sedação em ambos os grupos. O estudo revelou que o uso destes protocolos implica restrições para alguns parâmetros bioquímicos aqui estudados e que suas interpretações devem ser avaliadas cuidadosamente.

Formation of deep mesa-structures on SiC using fluoride plasma

A process of deep profiles formation on silicon carbide using ion-plasma etching in fluoride plasma is discussed. An industrial equipment «Caroline PE 15» (Russia) with ICP plasma source was used in experiments. The obtained experimental samples are perspective in power electronics applications.

Lipoprotein (a) and biochemical parameters in elderly

Background: Lipoprotein (a) [Lp(a)] is an low-density lipoprotein like particle and is an important independent risk factor for coronary artery diseases (CAD). Few studies on Lp(a) level in Thai elderly to screening risk of CAD may concerned. Aims: To study the relation of Lp(a) level and routine biochemical parameters including lipid profiles and fasting blood glucose in elderly and to determine risk of subclinical symptoms by using Lp(a) levels as early risk predictor. Settings and Design: Cross-sectional study during January to March 2015 at Amphawa district, Samut Songkhram province, Thailand. Materials and Methods: Anthropometric data and CAD risk factors (such as, blood pressure, cigarette smoking and body mass index) were recorded, and blood samples were collected from elderly farmers (N = 60). Each collected blood sample was prepared to serum for determining lipid profiles and sodium fluoride plasma for determine fasting blood glucose. Results : Only the average of prehypertension was out of reference range. There were found that Lp(a) can be used to indicate the risk of dyslipedemia [odds ratio (OR) = 8.80 and relative risk (RR) = 3.60] and prehypertension (OR = 15.67 and RR = 6.50). Statistical Analysis Used: The CAD risk and biochemical parameters were presented in mean ± standard deviation. The calculation of OR and RR of Lp (a) for hypercholesteremia, prediabetes, and prehypertension were calculated by MedCalc (Medcalc software bvba, Belgium). Conclusion: This study can be conclude that Lp(a) check together with lipid profile and blood pressure can be useful to screening of CAD with more accuracy especially in subclinical group.

Avaliação histopatológica da cápsula posterior associada ao implante de lente intraocular com superfície modificada com plasma de flúor e polietilenoglicol em coelhos

RESUMOO objetivo deste estudo foi avaliar o efeito do tratamento da superfície de lentes intraoculares acrílicas utilizando-se plasma de flúor ou polietilenoglicol na prevenção da opacidade de cápsula posterior. Foram analisados 40 olhos de coelhos, submetidos à cirurgia de facoemulsificação e distribuídos em quatro grupos experimentais (n=10), sendo estes: grupo controle, coelhos sem implante de lente intraocular; grupo com lente intraocular tratada com plasma de polietilenoglicol; grupo com lente intraocular tratada com plasma de flúor; e grupo com lente intraocular comercial. As cápsulas posteriores das lentes dos grupos foram avaliadas por meio de análise histopatológica (morfometria e imuno-histoquímica). Os grupos com lente intraocular tratada com polietilenoglicol e com lente intraocular comercial apresentaram menor espessura da cápsula posterior na avaliação inicial (12 semanas) em relação ao grupo controle. No período final de avaliação (6 meses), os tratamentos da superfície da lente intraocular à base de plasma de flúor e polietilenoglicol não reduziram o desenvolvimento das alterações histológicas associadas à opacidade de cápsula posterior. O tratamento das superfícies das lentes intraoculares com plasma de flúor e polietilenoglicol pode ser realizado como adjuvante na prevenção da opacidade de cápsula posterior, pois não causa alterações na morfologia da lente após facoemulsificação.

(Invited) The Stability of High Voltage AlGaN/GaN HEMTs

Si-based semiconductor devices have long dominated the power device market and are approaching their performance limit because of the inherent material limitations. On the other hand, wide bandgap semiconductors such as GaN and SiC promise significant performance boost coming from the superior material properties, such as a high critical electric field (3x106 V/cm), a high peak electron saturation velocity (2.5x107 cm/s), and a wide bandgap (3.4 eV) in GaN case [1]. In the III-nitride material system, a popular structure for power switching devices is the AlGaN/GaN HEMTs, because of the excellent two-dimensional electric gas (2DEG) in the hetrojunction interface, which greatly reduces the on-resistance of the device. Combined with the enhanced breakdown voltage from a large critical electric field, the figure of merit BV2/Ron,sp of reported AlGaN HEMTs have far surpassed the Si limit. The enhancement mode (E-mode) operation is strongly preferred for low power consumption, driver circuit simplicity, and fail-safe requirements for power electronic circuits. For AlGaN/GaN HEMTs realized utilizing epitaxial layers on the gallium face, the piezoelectric polarization, together with the spontaneous polarization, greatly enhances the 2DEG concentration, which is beneficial for reducing the on-resistance. But this makes it difficult to achieve the E-mode operation since the 2DEG under the gate region must vanish at zero gate bias. Several approaches have been proposed, including the recess gate structure, fluoride plasma treatment, the nano-ribbon channel, the p-GaN gate, and others. Although AlGaN/GaN HEMTs have demonstrated excellent performance with E-mode operation, their stability and reliability remains to be inspected before they can be commercialized. With different approaches to realize E-mode, the gate related stability problems arise differently depending on the gate design. In this work, we systematically investigate the stability of different device structures under different gate bias conditions, including Schottky gate HEMTs, p-GaN gate HEMTs, recessed MIS gate HEMTs, and multi-layer fluorinated MIS gate HEMTs. Figure 1 shows the pulsed Id-Vg characteristics of a recessed MIS gate AlGaN/GaN HEMT on a silicon substrate. The gate insulator is a 30 nm ALD deposited Al2O3 layer. The gate length is 3 μm and the gate-to-drain spacing is 20 μm for >1kV breakdown voltage. The pulse width is 5 ms and the period is 100 ms for all cases. The base voltage was varied from -15 V to 15 V and the drain current was measured during the pulse duration as shown in the inset. The threshold voltage Vth, which is defined when Id is 1mA/mm, increases with the base voltage, implying that negative charges are trapped in the gate insulator during the base duration. Figure 2 summarizes the extracted Vth for different gate structures using pulsed Id-Vg measurement with different gate base voltages. The Schottky gate HEMT shows a very stable Vth and Id-Vd characteristics against different pulse conditions but the negative Vth makes them less favorable. The p-GaN gate HEMT exhibits a positive but unstable Vth. The Vth shift can be as large as 1 V. Further annealing at 550oC in an O2ambient improves the p-type contact and hence the stability of the Vth but still limits the maximum gate voltage to 3 V. The decrease in Vth with increased gate base voltages implies trapping of holes in the p-GaN gate, which differs from the MIS gate device [2]. The MIS gate HEMT shows a positive threshold voltage about 6 V and a relatively large gate voltage swing. But the variation in the threshold voltage even at low gate base voltages indicates the occurrences of trapped charges in the gate insulator, which requires further examination and process improvement. More detailed discussion and measurement results will be shown. Acknowledgement This project was funded in part by financial support from Ministry of Economic Affairs 103A0002J9. Reference [1] T. P. Chow, R. Tyagi, IEEE Trans. Electron Devices 41(1994) 1481. [2] T.-F. Chang et al. to appear in IEEE Trans. Electron Devices. Figure 1

Simulation and Experimentation for Low Density Drain AlGaN/GaN HEMT

In order to improve the breakdown voltage of AlGaN/GaN high electron mobility transistors (HEMTs), we report a feasible method of low density drain (LDD) HEMT. The fluoride-based plasma treatment using CF4 gas is performed on the drain-side of the gate edge. The channel two-dimensional electron gas (2DEG) concentrations are modulated by fluoride plasma treatment, and the peak electric field at the gate edge is effectively reduced, so the breakdown voltage is improved. The electric field distributions of the LDD-HEMTs are simulated using the Silvaco software, and the peak of the electric field on the gate edge is effectively reduced. Experimental results show that, compared with the conventional HEMT, LDD-HEMTs have a lower reverse leakage current of the gate, and the breakdown voltage is increased by 36%. The current collapse characteristics of the LDD-HEMTs are confirmed by dual-pulse measurement, and an obvious pulse current reduction is due to the surface states by implanting F ions between the gate and the drain.

Quantitative Analysis of 26 Opioids, Cocaine, and Their Metabolites in Human Blood by Ultra Performance Liquid Chromatography–Tandem Mass Spectrometry

A sensitive and selective ultra performance liquid chromatographic-tandem mass spectrometric method was developed and fully validated for the simultaneous determination of (in order of chromatographic elution) methylecgonine, pholcodine, morphine, hydromorphone, oxymorphone, norcodeine, codeine, dihydrocodeine, oxycodone, 6-Monoacetylmorphine (6-MAM), hydrocodone, ethylmorphine, norfentanyl, benzoylecgonine, tramadol, normeperidine, meperidine, cocaine, pentazocine, cocaethylene, fentanyl, norbuprenorphine, 2-ethylidine-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), buprenorphine, propoxyphene, and methadone in blood. The matrixes analyzed during the validation experiments were as follows: citrated blank plasma for calibrators, fluoride blank plasma for internal quality control (QC), lyophilized serum for external QC, fluoride plasma and whole blood for authentic samples, and lyophilized serum and whole blood for proficiency testing schemes. Samples were extracted with cation exchange solid-phase extraction cartridges. The target drugs were separated and quantified in a chromatographic run of 8.1 minutes using 0.1% formic acid in water and methanol (with 0.1% formic acid) as mobile phase. The limit of quantification ranged from 0.5 to 2.5 ng/mL depending on the compound and the therapeutic concentration. The intra- and interassay precision was less than 15% for all the compounds (except for pentazocine and EDDP, which was <20%) determined with 2 internal and 2 external QC samples, and the bias was within ±15% (except for methylecgonine, which was <20%). Extraction efficiency was greater than 70% for all the compounds except for EDDP. Matrix effects were evaluated with authentic blood samples (n = 10), and they ranged from 47 to 95%, but they were compensated for most analytes using deuterated analogs as internal standards. Prepared samples were stable for 62 hours in the autosampler. This method was successfully applied to authentic samples (n = 120), involving the use of heroin, cocaine, tramadol, and methadone, and to proficiency testing schemes.

Validation of handheld meters to measure blood l-lactate concentration in dairy cows and calves

In cattle, blood lactate was measured in various conditions such as parturition and dystocia. To our knowledge, to date, no handheld device has been validated for the use in cows and only one handheld device was validated for the use in calves. When determining plasma lactate concentrations blood samples have to be processed carefully. Sodium fluoride was recommended to inhibit glycolysis and to stabilize plasma lactate concentrations during transport. However, its effect on measurements conducted with electrochemical meters has not been studied. The objectives of 3 experiments were to study factors influencing measures of l-lactate in dairy cows (e.g., different anticoagulants, different methods) and to validate a handheld device (Lactate Scout, SensLab GmbH, Leipzig, Germany) to determine l-lactate concentration in dairy cows and calves. In a first approach, blood samples from 49 cows were analyzed by 2 different laboratories. Measures of l-lactate concentration were correlated between the different laboratories in both lithium heparin plasma (r=0.98) and sodium fluoride plasma (r=0.99). In a second approach, these samples were analyzed using 3 methods [Lactate Scout, Biosen C_line (EKF Diagnostics GmbH, Barleben, Germany), and commercial laboratory]. Concentrations of l-lactate measured in lithium heparin did not differ when analyzed with the Lactate Scout (0.99±0.35mmol/L), the Biosen C_line (0.81±0.26mmol/L), or the laboratory (1.0±0.36mmol/L). Concentrations of l-lactate measured in sodium fluoride, however, were higher when analyzed with the Lactate Scout (1.85±0.66mmol/L) compared with those measured with the Biosen C_line (0.92±0.37mmol/L) and by the commercial laboratory (0.72±0.45mmol/L). In the second and third experiments, blood samples from 173 cows and 106 calves were analyzed using the 3 methods (Lactate Scout, Biosen C_line, and commercial laboratory). l-Lactate concentrations measured with the 3 methods were correlated (cows: Lactate Scout vs. Biosen C_line: r=0.97, Lactate Scout vs. laboratory 1: r=0.98, Biosen C_line vs. laboratory 1: r=0.99; calves: Lactate Scout vs. Biosen C_line: r=0.97, Lactate Scout vs. laboratory 1: r=0.98, Biosen C_line vs. laboratory 1: r=0.99). In conclusion, Lactate Scout and Biosen C_line measure blood l-lactate concentrations reliably compared with a commercial laboratory as the reference method in dairy cows and calves. However, attention needs to be paid to the choice of anticoagulant used in sample collection.

Spatial diagnostics of the laser induced lithium fluoride plasma

We present spatial characteristics of the lithium fluoride plasma generated by the fundamental and second harmonic of a Nd:YAG laser. The plume emission has been recorded spatially using five spectrometers covering the spectral region from 200 nm to 720 nm. The electron density is measured from the Stark broadened line profile of the line at 610.37 nm, whereas the plasma temperature has been determined using the Boltzmann plot method including all the observed spectral lines of lithium. Both the plasma parameters; electron density and plasma temperature decrease with the increase of the distance from the target surface. The thermal conduction towards the target, the radiative cooling of the plasma, and the conversion of thermal energy into kinetic energy are the main mechanisms responsible for the spatially decrease of the plasma parameters.

Blood glucose determination: plasma or serum?

Blood glucose determination is one of the most common clinical diagnostic tests. Often, blood is collected in a field station and analysis is carried out in a remote laboratory. Because blood cells can continue to metabolize glucose, the time of determination of blood glucose after drawing the blood is important. In order to test the relative suitability of plasma and serum for blood glucose determination, fluoride plasma and Ethylene Diamine Tetra Acetic acid (EDTA) plasma were compared with the serum of the same patient. The analyses were carried out within 10 min of drawing the blood and, thereafter, with a gap of 4 hr and 8 hr. Serum gave values lower than fluoride plasma by 1.15%. Although this difference was statistically significant, it may not be physiologically relevant. Hence, serum may be used for blood glucose determination with an error of 1.15%. On storing the sample at room temperature for 8 hr, the serum glucose value decreased by 8%. Even fluoride plasma had 4.3% lower glucose. Hence, blood glucose should be determined within as short a time as possible after drawing the blood.