Effects of pressurized hot water extraction on the nanoscale structure of birch sawdust

Pressurized hot water extraction with a flow-through system was used to extract hemicelluloses and lignin from birch sawdust. The structure of the extraction residue was studied on various levels. Molecular mass distributions were determined with gel permeation chromatography and the crystal structure of cellulose was characterized using wide-angle X-ray scattering (WAXS). Information on the short-range order of cellulose microfibrils and on the nanoscale pore structure was obtained with small-angle X-ray scattering (SAXS), and the micrometre scale cellular morphology was imaged with X-ray microtomography. The pressurized hot water treatment was observed to increase the lateral width of cellulose crystallites, determined with WAXS, whereas a possible small decrease in the crystallinity of cellulose compared to native wood was detected. The molecular mass of cellulose remained at a relatively high level. According to the SAXS results, a tighter lateral association of cellulose microfibrils was observed in the extracted samples, which possibly led to opening of pores between bundles of microfibrils, as indicated by an increased specific surface area. A reduction in the thickness of the fibre cell walls was evidenced by X-ray microtomography.     

A physiological and acoustic study on voiced bilabial fricative /β:/ as a vocal exercise

The voiced bilabial fricative /β:/ has been used as a vocal exercise. The present study investigated the effects of the exercise on voice production and voice source. This study compared vowel phonation on the syllable /a:p/ with the production of the exercise and vowel phonation before and immediately after the exercise. The methods were (a) dual-channel electroglottography, from which the vertical laryngeal position was derived, (b) electromyography using surface electrodes, and (c) inverse filtering of the acoustic signal to obtain an estimate of the voice source. In the production of /β:/ as compared with vowel phonation in most of the cases, the vertical laryngeal position seemed to be higher, the muscular activity of the larynx lower, and the slope of the voice source spectrum steeper. In vowel phonation after the exercise, the muscular activity seemed to be lower in most cases, although the voice source remained unchanged. This seems to indicate improved vocal economy.     

Analysis of superconductor oxides YBa2Cu3O8−x by inductively coupled plasma atomic emission spectrometry and complexometric titration

The elemental composition of superconductor oxides YBa₂Cu₃O_8−x were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and complexometric titration. Samples were dissolved in dilute HCl. A sequential PU 7000 Philips inductively coupled plasma atomic emission spectrometer was used for the measurements. A comparison of the different atom and ion emission lines of yttrium, barium and copper was carried out. The effect of changes of forward radio frequency (RF) power coupled into the plasma on emission intensity of various spectral lines was studied. The RF power was changed from 0.8 to 1.2 kW. The changes in the net intensities (%) of the emission lines of Cu(I) at 324.754 nm, Cu(II) at 224.700 nm, Ba(II) at 455.403, Ba(II) at 493.409 nm, Y(II) at 371.030 nm and Y(II) at 360.073 nm were calculated. The indicator 1-(2-Pyridylazo)-2-Naphthol (PAN) and different buffers were used for the complexometric titration of Cu, Y and Ba. No statistically significant differences were found between the results of ICP-AES and chemical methods of analysis.     

Biodegradabilities of some chain oils in groundwater as determined by the respirometric BOD OxiTop method

The respirometric BOD OxiTop method was used to monitor the biodegradation of different chain oils (mineral, rapeseed and tall oils) over 28 days in groundwater, as well as in standard conditions described by OECD 301 F. The aim of the study was to gather more information about the biodegradability of forestry oils in groundwater, as well as about the suitability of the automatic OxiTop method for biodegradation measurements. The BOD OxiTop method proved to be a precise and reliable technique for determining the biodegradations of different oils. Some comparative studies were also made using a traditional IR method in order to clarify the total oil concentrations. The results show that if biodegradation only is to be monitored, the OxiTop method is preferable. This is due to the influence of other reactions aside from biodegradation on total hydrocarbon concentrations when using the IR method.     

Increasing surface charge density induces interdigitation in vesicles of cationic amphiphile and phosphatidylcholine

Binary vesicles of cationic lipid dihexadecyldimethylammoniumbromide (DHAB) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) were examined by differential scanning calorimetry, fluorescence spectroscopy, and Fourier transform infrared spectroscopy. DHAB/DMPC vesicles demonstrate a complex dependence of the main-transition temperature (T(m)) on their mole proportion of DHAB, with a maximum of 42 degrees C at X(DHAB) = 0.4. An increase of T(m) at X(DHAB) < 0.4 is explained by reorientation of P(-)-N(+) dipoles of the phosphocholine headgroup, resulting in tighter packing of the acyl chains, which increases the thermal energy required for trans --> gauche isomerization. At X(DHAB) > 0.4, Coulombic repulsion between the cationic DHAB headgroups expands the bilayer evident as a decrease in T(m) until a plateau of approximately 28 degrees C at 0.7 < or = X(DHAB) > or = 0.9 is reached, followed by an increment of T(m) to approximately 30 degrees C at X(DHAB) > 0.9. The quenching of DPH-PC fluorescence emission and the decrease in the ratio of peak height intensities of symmetric and antisymmetric -CH(2)- stretching modes suggest an interdigitated phase to form at X(DHAB) > 0.6. Interdigitation allows the membrane to accommodate the augmented Coulombic repulsion between DHAB headgroups because of increasing cationic surface charge density while simultaneously causing tighter packing of the acyl chains evident first as a plateau at 0.7 < or = X(DHAB) > or = 0.9 and subsequently as an increase in T(m) at X(DHAB) > 0.9. Screening of the membrane charges by NaCl abolishes the quenching of DPH emission and decreases T(m), thus revealing electrostatic repulsion as the driving force for interdigitation.     

Interaction of cytochrome c with 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine: evidence for acyl chain reversal

The conformational dynamics of the oxidatively modified phospholipid 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC) were assessed by observing by fluorescence energy transfer the association of the water-soluble cationic protein cytochrome c with micelles composed of this lipid. In keeping with reversal of the azelaoyl chain so as to expose its carboxyl function on the micelle surface, cytochrome c bound avidly to the micelles. In contrast, the aldehyde group bearing 1-palmitoyl-2-(9'-oxo-nonanoyl)-sn-glycero-3-phosphocholine (PoxnoPC) interacted only weakly. While the physiological significance of the above interaction is uncertain, our results demonstrate that oxidative damage alters the physical properties of lipid bilayers, involving enrichment of the polar moieties of oxidatively modified lipid chains within the membrane surface.     

On First Range Times of Linear Diffusions

In this paper we consider first range times (with randomised range level) of a linear diffusion on R. Inspired by the observation that the exponentially randomised range time has the same law as a similarly randomised first exit time from an interval, we study a large family of non-negative 2-dimensional random variables (X,X′) with this property. The defining feature of the family is F^c(x,y)=F^c(x+y,0), ∀ x ≥ 0, y ≥ 0, where F^c(x,y):=P (X > x, X′ > y) We also explain the Markovian structure of the Brownian local time process when stopped at an exponentially randomised first range time. It is seen that squared Bessel processes with drift are serving hereby as a Markovian element.     

Objective Analysis of Vocal Warm-Up with Special Reference to Ergonomic Factors

Vocal warm-up was studied in terms of changes in voice parameters during a 45-minute vocal loading session in the morning. The voices of a randomly chosen group of 40 female and 40 male young students were loaded by having them read a novel aloud. The exposure groups (5 females and 5 males per cell) consisted of eight combinations of the following factors: (1) low (25 +/- 5%) or high (65 +/- 5%) relative humidity of ambient air; (2) low [< 65 dB(SPL)] or high [> 65 dB(SPL)] speech output level during vocal loading; (3) sitting or standing posture during vocal loading. Two sets of voice samples were recorded: a resting sample before the loading session and a loading sample after the loading session. The material recorded consisted of /pa:ppa/ words produced normally, as softly and as loudly as possible in this order by all subjects. The long /a/ vowel of the test word was inverse-filtered to obtain the glottal flow waveform. Time domain parameters of the glottal flow [open quotient (OQ), closing quotient (CQ), speed quotient (SQ), fundamental frequency (F0)], amplitude domain parameters of the glottal flow [glottal flow (fAC) and its logarithm, minimum of the first derivative of the glottal flow (dpeak) and its logarithm, amplitude quotient (AQ), and a new parameter, CQAQ], intraoral pressure (p), and sound pressure level (SPL) values of the phonations were analyzed. Voice range profiles (VRP) and the singer's formant (g/G, a/A, cl/c, e1/e, g1/g for females/males) of the loud phonation were also measured. Statistically significant differences between the preloading and postloading samples could be seen in many parameters, but the differences depended on gender and the type of phonation. In females the values of CQ, AQ, and CQAQ decreased and the values of SQ and p increased in normal phonations; the values of fAC, dpeak, and SPL increased in soft phonations; the values of AQ and CQAQ decreased in loud phonations; the harmonic energy in the singer's formant region increased significantly at every pitch. In males the values of OQ and AQ decreased and the values of dpeak, F0, p, and SPL increased in normal phonations; the values of fAC and p increased in soft phonations. The changes could be interpreted as signs of a shift toward hyperfunctional voice production. Low humidity was associated with more hyperfunctional changes than high humidity. High output was associated with more hyperfunctional changes than low output. Sitting position was associated with an increasing trend at both margins of male VRP, whereas the case was the opposite for standing position.     

Microwave sample-digestion procedure for determination of arsenic in moss samples using electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry

Arsenic in moss samples was determined by electrothermal atomic absorption spectrometry (ETAAS) after microwave-assisted sample digestion. Two different sample masses (500 mg and 1000 mg) and three different microwave ovens were used in the digestion. There was a slight difference in the digestion efficiency, as determined by the residual carbon concentrations of 500 mg digested samples, between the microwave ovens. The arsenic results obtained for moss reference samples were, in most cases, satisfactory. However, phosphorus was found to have a reducing influence on the arsenic peak area in the ETAAS determination. According to the results, it was not possible to reduce the phosphorus interference by increasing the amount of Mg(NO(3))(2) in the Pd-Mg chemical modifier. The arsenic results obtained by ETAAS were compared to those obtained by inductively coupled plasma mass spectrometry (ICP-MS).