Sensor application-related defect chemistry and electromechanical properties of langasite

The operation of langasite (La₃Ga₅SiO₁₄) resonators as sensors at elevated temperature and controlled atmospheres is examined. This paper focuses on mapping the regimes of gas-insensitive operation of uncoated langasite resonators and the correlation to langasite's defect chemistry for temperatures up to 1000 °C. As a measure of sensitivity, the fundamental resonant mode at 5 MHz is estimated to be determined to within ± 4 Hz by network analysis for resonators operated in air at temperatures below 1000 °C. The calculated frequency shift induced by redox-related reactions in langasite only exceeds the limit of ± 4 Hz below p_O2 ≈ 10^− 17 bar at 1000 °C, below 10^− 24 bar at 800 °C and below 10^− 36 bar at 600 °C. Water vapor is found to shift the resonance frequency at higher oxygen partial pressures. In the hydrogen-containing atmospheres applied here, langasite can be regarded as a stable resonator material above oxygen partial pressures of about 10^− 13 and 10^− 20 bar at 800 and 600 °C, respectively.     

Resonator micro optic gyro with double phase modulation technique using an FPGA-based digital processor

Experiments on resonator micro-optic gyro (RMOG) with a digital proportional integral (PI) feedback scheme are performed. In this experimental setup, the key rotation sensing element is a polarization maintaining silica waveguide ring resonator (WRR) with a ring length of 7.9 cm and a diameter of 2.5 cm. A good linearity of 0.0015% over a wide range of ± 2 × 10⁴ °/s can be achieved for the RMOG theoretically. The optimal digital PI feedback scheme is adopted in the frequency servo loop to reduce the reciprocal frequency fluctuations due to the WRR resonance frequency and laser frequency drifts. Residual equivalent input fluctuation can be reduced as low as 0.03 °/s/√Hz based on the optimal digital PI feedback scheme, which is close to the shot noise limited spectral density 0.02 °/s/√Hz of the RMOG with the input optical power of 0.2 mW. Relationship between RMOG output signal and angular rate is obtained from ± 0.1 °/s to ± 5 °/s. The standard deviation of the residuals between RMOG output results and linear fit curve is 0.066 °/s. For an integration of the processing circuit, all the processing circuit is implemented by a field programmable gate array (FPGA) instead of instruments. The output of this digitalized RMOG is obtained over a range of ± 550 °/s. The linearity of this digitalized RMOG is 0.0169%.     

Temperature effects on the ultrasonic separation of fat from natural whole milk

This study showed that temperature influences the rate of separation of fat from natural whole milk during application of ultrasonic standing waves. In this study, natural whole milk was sonicated at 600 kHz (583 W/L) or 1 MHz (311 W/L) with a starting bulk temperature of 5, 25, or 40 °C. Comparisons on separation efficiency were performed with and without sonication. Sonication using 1 MHz for 5 min at 25 °C was shown to be more effective for fat separation than the other conditions tested with and without ultrasound, resulting in a relative change from 3.5 ± 0.06% (w/v) fat initially, of −52.3 ± 2.3% (reduction to 1.6 ± 0.07% (w/v) fat) in the skimmed milk layer and 184.8 ± 33.2% (increase to 9.9 ± 1.0% (w/v) fat) in the top layer, at an average skimming rate of ∼5 g fat/min. A shift in the volume weighted mean diameter (D[4,3]) of the milk samples obtained from the top and bottom of between 8% and 10% relative to an initial sample D[4,3] value of 4.5 ± 0.06 μm was also achieved under these conditions. In general, faster fat separation was seen in natural milk when natural creaming occurred at room temperature and this separation trend was enhanced after the application of high frequency ultrasound.     

Accelerating MRI fat quantification using a signal model-based dictionary to assess gastric fat volume and distribution of fat fraction

To quantify intragastric fat volume and distribution with accelerated magnetic resonance (MR) imaging using signal model-based dictionaries (DICT) in comparison to conventional parallel imaging (CG-SENSE). This study was approved by the local ethics committee and written informed consent was obtained. Seven healthy subjects were imaged after intake of a lipid emulsion and data at three different time points during the gastric emptying process was acquired in order to cover a range of fat fractions. Fully sampled and prospectively undersampled image data at a reduction factor of 4 were acquired using a multi gradient echo sequence at 1.5T. Retrospectively and prospectively undersampled data were reconstructed with DICT and CG-SENSE. Image quality of the retrospectively undersampled data was assessed relative to the fully sampled reference using the root mean square error (RMSE). In order to assess the agreement of fat volumes and intragastric fat distribution, Bland-Altman analysis and linear regression were performed on the data. The RMSE in intragastric content (ΔRMSE = 0.10 ± 0.01, P < 0.001) decreased significantly with DICT relative to CG-SENSE. CG-SENSE overestimated fat volumes (bias 2.1 ± 1.3 mL; confidence limits 5.4 and − 1.1 mL) in comparison to the prospective DICT reconstruction (bias − 0.1 ± 0.7 mL; confidence limits 1.8 and − 2.0 mL). There was a good agreement in fat distribution between the images reconstructed by retrospective DICT and the reference images (regression slope: 1.01, R² = 0.961). Accelerating gastric MRI by integrating a dictionary-based signal model allows for improved image quality and increases accuracy of fat quantification during breathholds.     

Water and lipid diffusion MRI using chemical shift displacement-based separation of lipid tissue (SPLIT)

PurposeTo obtain water and lipid diffusion-weighted images (DWIs) simultaneously, we devised a novel method utilizing chemical shift displacement-based separation of lipid tissue (SPLIT) imaging.Materials and methodsSingle-shot diffusion echo-planar imaging without fat suppression was used and the imaging parameters were optimized to separate water and lipid DWIs by chemical shift displacement of the lipid signals along the phase-encoding direction. Using the optimized conditions, transverse DWIs at the maximum diameter of the right calf were scanned with multiple b-values in five healthy subjects. Then, apparent diffusion coefficients (ADCs) were calculated in the tibialis anterior muscle (TA), tibialis bone marrow (TB), and subcutaneous fat (SF), as well as restricted and perfusion-related diffusion coefficients (D and D*, respectively) and the fraction of the perfusion-related diffusion component (F) for TA.ResultsWater and lipid DWIs were separated adequately. The mean ADCs of the TA, TB, and SF were 1.56 ± 0.03 mm²/s, 0.01 ± 0.01 mm²/s, and 0.06 ± 0.02 mm²/s, respectively. The mean D*, D, and F of the TA were 13.7 ± 4.3 mm²/s, 1.48 ± 0.05 mm²/s, and 4.3 ± 1.6%, respectively.ConclusionSPLIT imaging makes it possible to simply and simultaneously obtain water and lipid DWIs without special pulse sequence and increases the amount of diffusion information of water and lipid tissue.     

Dynamical XPS measurements for probing photoinduced voltage changes

Photoillumination with 405 nm laser causes shifts in XPS peaks of n-Si(100), and CdS. To distinguish between surface photovoltage (SPV), and charging, dynamical measurements are performed, while sample is subjected to square wave pulses of ± 10.00 V amplitude, and 10^?3–10⁵ Hz frequency. For n-Si, Si2p peaks are twinned at + 10.00 and ?10.00, yielding always 20.00 eV difference. Photoillumination shifts the twinned peaks to higher energies, but the difference is always 20.00 eV. However, for CdS, the measured binding difference of Cd3d peaks exhibits strong frequency dependence due to charging, which indicates that both fast SPV and slow charging effects are operative.     

Fabry–Pérot cavities based on chemical etching for high temperature and strain measurement

In this paper, two hybrid multimode/single mode fiber Fabry–Pérot (FP) cavities were compared. The cavities fabricated by chemical etching are presented as high temperature and strain sensors. In order to produce this FP cavity a single mode fiber was spliced to a graded index multimode fiber with 62.5 μm core diameter. The Fabry–Pérot cavities were tested as a high temperature sensor in the range between room temperature and 700 °C and as strain sensors. A reversible shift of the interferometric peaks with temperature allowed to estimate a sensitivity of 0.75 ± 0.03 pm/°C and 0.98 ± 0.04 pm/°C for the sensor A and B respectively. For strain measurement sensor A demonstrated a sensitivity of 1.85 ± 0.07 pm/μ? and sensor B showed a sensitivity of 3.14 ± 0.05 pm/μ?. The sensors demonstrated the feasibility of low cost fiber optic sensors for high temperature and strain.     

Ultrasonic and mechanical soil washing processes for the removal of heavy metals from soils

In order to determine the optimal operating conditions of full-scale soil washing processes for the removal of heavy metals, the effect of high-power ultrasound on the conventional mechanical soil washing process was investigated in a large lab-scale 28 kHz sonoreactor. The soil samples were obtained from an abandoned railway station site in Seoul, Korea, which was contaminated with Cu (242.7 ± 40.0 mg/kg), Pb (441.3 ± 49.8 mg/kg), and Zn (358.0 ± 35.7 mg/kg). The treated concentrations of three heavy metal species in each process were compared with the regulation levels. It was found that higher performance, satisfying the regulation levels, was obtained in the ultrasonic/mechanical process due to the combined effects of macroscale mixing and microscale sonophysical effects. Moreover ultrasound played a more important role in less favorable conditions for the mechanical washing process (less acidic or less washing liquid conditions). Considering the application of the ultrasonic/mechanical soil washing process in real contaminated sites, the optimal conditions for the reactor with the bottom area of 15 × 15 cm² and the input ultrasound power of 250 W were determined as follows: (1) the amount of soil per an operation was a 300 g; (2) the ratio of soil and liquid was 1:3; (3) the concentration of acidic washing liquid was 0.5 M HCl.     

Low frequency properties of micro power generator using a gold electroplated coil and magnet

Micro power generating devices were fabricated by using a gold electroplated coil and a permanent magnet. The electrical power was generated when the magnet reciprocated on the fabricated electroplated coil. The output power was increased as a function of vibration frequency. A measurement system, which convert a rotational motion of a motor into a linear motion, was designed and fabricated. The purpose of this work is to develop the micro power generating devices which convert the ambient vibration or oscillating energy into useful electrical energy. With changing vibration frequency from 0.5 to 8 Hz, the generated power increased linearly. The generated voltage was 106 mV at 3 Hz and 198 mV at 6 Hz. After using the step up circuit, the measured voltage was 81 mV at 3 Hz and 235 mV at 6 Hz. From above the frequency of about 4.5 Hz, the gain obtained by using the quadrupler circuit becomes larger than the loss without using that circuit.     

The vibration of inclined backrests: perception and discomfort of vibration applied normal to the back in the x-axis of the body

The vibration of backrests contributes to the discomfort of drivers and passengers. A frequency weighting exists for evaluating the vibration of vertical backrests but not for reclined backrests often used during travel. This experimental study was designed to determine how backrest inclination and the frequency of vibration influence perception thresholds and vibration discomfort when the vibration is applied normal to the back (i.e. fore-and-aft vibration when seated upright and vertical vibration when fully reclined). Twelve subjects experienced the vibration of a backrest (at each of the 11 preferred one-third octave centre frequencies in the range 2.5–25 Hz) at vibration magnitudes from the threshold of perception to 24 dB above threshold. Initially, absolute thresholds for the perception of vibration were determined with four backrest inclinations: 0° (upright), 30°, 60° and 90° (recumbent). The method of magnitude estimation was then used to obtain judgements of vibration discomfort with each of the four backrest angles. Finally, the relative discomfort between the four backrest angles, and the principal locations for feeling vibration discomfort in the body, were determined. With all backrest inclinations, absolute thresholds for the perception of vibration acceleration were dependent on the frequency of vibration. As the backrest inclination became more horizontal, the thresholds increased at frequencies between 4 and 8 Hz. For all backrest inclinations, the rate of growth of discomfort with increasing magnitude of vibration was independent of the frequency of vibration, so the frequency-dependence of discomfort was similar over the range of magnitudes investigated (0.04–0.6 m s^?2 rms). With an upright backrest, the discomfort caused by vibration acceleration tended to be greatest at frequencies less than about 8 Hz. With inclined backrests (at 30°, 60°, and 90°), the equivalent comfort contours were broadly similar to each other, with greatest discomfort caused by acceleration around 10 or 12.5 Hz. At frequencies from 4 to 8 Hz, 30–40 percent greater magnitudes of vibration were required with the three inclined backrests to cause discomfort equivalent to that caused by the upright backrest. It is concluded that with an upright backrest the frequency weighting W_c used in current standards is appropriate for predicting the discomfort caused by fore-and-aft backrest vibration. With inclined and horizontal backrests, a weighting similar to frequency weighting W_b (used to predict discomfort caused by vertical seat vibration) appears more appropriate.     

Instant controlled pressure drop technology and ultrasound assisted extraction for sequential extraction of essential oil and antioxidants

The instant controlled pressure drop (DIC) technology enabled both the extraction of essential oil and the expansion of the matrix itself which improved solvent extraction. The sequential use of DIC and Ultrasound Assisted Extraction (UAE) triggered complementary actions materialized by supplementary effects. We visualized these combination impacts by comparing them to standard techniques: Hydrodistillation (HD) and Solvent Extraction (SE). First, the extraction of orange peel Essential Oils (EO) was achieved by HD during 4 h and DIC process (after optimization) during 2 min; EO yields was 1.97 mg/g dry material (dm) with HD compared to 16.57 mg/g dm with DIC. Second, the solid residue was recovered to extract antioxidant compounds (naringin and hesperidin) by SE and UAE. Scanning electron microscope showed that after HD the recovered solid shriveled as opposite to DIC treatment which expanded the product structure. HPLC analyses showed that the best kinetics and yields of naringin and hesperidin extraction was when DIC and UAE are combined. Indeed, after 1 h of extraction, DIC treated orange peels with UAE were 0.825 ± 1.6 × 10^?2 g/g of dry material (dm) for hesperidin and 6.45 × 10^?2 ± 2.3 × 10^?4 g/g dm for naringin compared to 0.64 ± 2.7 × 10^?2 g/g of dry material (dm) and 5.7 × 10^?2 ± 1.6 × 10^?3 g/g dm, respectively with SE. By combining DIC to UAE, it was possible to enhance kinetics and yields of antioxidant extraction.     

Acid-induced gelation behavior of soybean protein isolate with high intensity ultrasonic pre-treatments

High intensity ultrasonic (HUS, 20 k Hz, 400 W) pre-treatments of soybean protein isolate (SPI) improved the water holding capacity (WHC), gel strength and gel firmness (final elastic moduli) of glucono-δ-lactone induced SPI gels (GISG). Sonication time (0, 5, 20, and 40 min) had a significant effect on the above three properties. 20 min HUS-GISG had the highest WHC (95.53 ± 0.25%), gel strength (60.90 ± 2.87 g) and gel firmness (96340 Pa), compared with other samples. Moreover, SH groups and non-covalent interactions of GISG also changed after HUS pre-treatments. The HUS GISG had denser and more uniform microstructures than the untreated GISG. Rheological investments showed that the cooling step (reduce the temperature from 95 to 25 °C at a speed of 2 °C/min) was more important for the HUS GISG network formation while the heat preservation step (keep temperature at 95 for 20 min) was more important for the untreated GISG. HUS reduced the particle size of SPI and Pearson correlation test showed that the particle size of SPI dispersions was negatively correlated with WHC, gel strength and gel firmness.     

Ultrasonically tailored,chemically engineered and “QbD” enabled fabrication of agomelatine nanoemulsion; optimization,characterization, ex-vivo permeation and stability study

The objective of present study was to develop a nanoemulsion formulation of agomelatine (BCS class II drug) for the solubility enhancement. Capmul MCM, Tween 80 and PEG-400 were selected as oil, surfactant and co-surfactant respectively. The high energy ultrasonication method was used for the preparation of nanoemulsion. Three-factor three-level central composite design was employed to get the best formulation. The independent variables selected for the optimization were % oil, %S_mix and sonication time (second). Based on the constraints applied to independent and dependent variables, the optimized formulation was selected with 2% oil, 10% S_mix and 45 s sonication time. The experimental values for dependent variables such as hydrodynamic diameter (nm), % transmittance and % CDR were found to be 73.72 ± 2.53 nm, 98.2 ± 0.42%, 84.71 ± 4.05% respectively. TEM and AFM−assisted morphological characterization of optimized Ago-NE was done and it was found with a spherical shape. The PDI, Zeta potential and the refractive index of optimized Ago-NE were found to be 0.137 ± 0.016, −7.40 ± 0.12 mV and 1.423 ± 0.045 respectively. The viscosity, pH and drug content of optimized Ago-NE were found as 25.12 ± 0.67 cP, 6.4 ± 0.17 and 97.83 ± 1.03% respectively. The ex-vivo permeation profile of optimized Ago-NE and agomelatine suspension through goat nasal mucosa were compared till 12 h and % cumulative drug permeated was found to be 90% and 40% respectively. The higher drug permeation profile of optimized Ago-NE confirmed that the solubility of agomelatine has been improved.     

Mechanical bioeffects of acoustic droplet vaporization in vessel-mimicking phantoms

This study investigated the mechanical bioeffects exerted by acoustic droplet vaporization (ADV) under different experimental conditions using vessel phantoms with a 200-μm inner diameter but different stiffness for imitating the microvasculature in various tumors. High-speed microscopy, passive cavitation detection, and ultrasound attenuation measurement were conducted to determine the morphological characteristics of vascular damage and clarify the mechanisms by which the damage was initiated and developed. The results show that phantom erosion was initiated under successive ultrasound exposure (2 MHz, 3 cycles) at above 8-MPa peak negative pressures (PNPs) when ADV occurred with inertial cavitation (IC), producing lesions whose morphological characteristics were dependent on the amount of vaporized droplets. Slight injury occurred at droplet concentrations below (2.6 ± 0.2) × 10⁶ droplets/mL, forming shallow and rugged surfaces on both sides of the vessel walls. Increasing the droplet concentration to up to (2.6 ± 0.2) × 10⁷ droplets/mL gradually suppressed the damage on the distal wall, and turned the rugged surface on the proximal wall into tunnels rapidly elongating in the direction opposite to ultrasound propagation. Increasing the PNP did not increase the maximum tunnel depth after the ADV efficiency reached a plateau (about 71.6 ± 2.7% at 10 MPa). Increasing the pulse duration effectively increased the maximum tunnel depth to more than 10 times the diameter of the vessel even though there was no marked enhancement in IC dose. It can be inferred that substantial bubble generation in single ADV events may simultaneously distort the acoustic pressure distribution. The backward ultrasound reinforcement and forward ultrasound shielding relative to the direction of wave propagation augment the propensity of backward erosion. The results of the present work provide information that is valuable for the prevention or utilization of ADV-mediated mechanical bioeffects in clinical applications.     

Structure relates to elastic recoil and functional role in quadriceps tendon and patellar ligament

Tendons and ligaments have similar but slightly different structure and composition. Crimps of tendons and ligaments are morphological structures related to the elastic functional properties of these connective tissues. Aim of this study was to investigate the morphological arrangement of collagen fibres, fibrils and crimping pattern of suprapatellar (rectus femoris tendon-RFT and vastus intermedius tendon-VIT) and infrapatellar connective tissues (patellar ligament-PL) to relate their structural aspects to their common function role of leg extension. RFT, VIT and PL were removed from knees of Sprague–Dawley rats and light and electron microscopy (TEM and SEM) performed. Sagittal sections showed that collagen array and crimping pattern were similar in RFT and PL but differed from VIT. Morphometric analysis confirmed that crimp number was about the same in RFT and PL (5.4 ± 1.4 and 6.1 ± 2.8 respectively), but it was almost three times higher in VIT (14.5 ± 4.7). Similarly crimp top angle in RFT and PL (141.5 ± 15.0° and 146.2 ± 12.2° respectively) was significantly higher than in VIT (122.3 ± 14.8°) and the crimp base length was more than twice as wide in RFT (75.5 ± 22.6 μm) and PL (72.3 ± 28.9 μm) than in VIT (36 ± 14.1 μm). The smaller, fewer and most crimped crimps in VIT show that this tendon has a greater elastic recoil and responds to higher forces as among quadriceps muscles the vastus intermedius belly contributes the most during knee extension. By contrast, RFT acting as a “stopper” tendon also plays a ligament role by limiting an excessive flexion of the joint during postural rest position of the knee.     

Formulation of saponin stabilized nanoemulsion by ultrasonic method and its role to protect the degradation of quercitin from UV light

The objective of the present study was to prepare quercitin (QT) loaded o/w nanoemulsion using food grade surfactants (saponin and tween 80). The prepared nanoemulsion) was stable up to 30 days. The average particle size of the nanoemulsion was 52 ± 10 nm. The formation of saponin stabilized nanoemulsion was confirmed by transmission electron microscopy. Quercitin (QT) trapped nanoemulsion showed higher stability on exposure to UV light (254 nm) as compared to water/ethanol system. The degradation rate was found to decrease from 9 ± 1%, 11 ± 1% at pH 7.4, 8.0 respectively as compared to 42 ± 2% in water/ethanol system. Attempt was also made to study the interaction of QT with two different bile salts (sodium cholate and sodium taurocholate). The free radical scavenging activity of DPPH quercitin and curcumin was compared in NEm media. The obtained IC₅₀ value of quercitin, curcumin and ascorbic acid are 28.88 ± 1, 45.53 ± 2 and 51.51 ± 2 μM respectively. The values of binding constant for sodium cholate (NaC) and sodium taurocholate (NaTC) are 2.66 × 10⁵ and 2.72 × 10⁴ M⁻¹ respectively. Sodium cholate (NaC) was found to show strong interaction towards quercitin (QT) due to more electron density on oxygen atom of carboxylate ion.     

Design optimization of porous fibrous material for maximizing absorption of sounds under set frequency bands

In this paper, a methodology is proposed for designing porous fibrous material with optimal sound absorption under set frequency bands. The material is assumed to have a rigid frame and a hexagonal arrangement of fibers, and the analytical model derived by Johnson, Champoux and Allard (“JCA model”) is used to investigate the influences of the micro-structural parameters (fiber radius r and gap w) on sound absorption performance, and the macro-acoustic parameters used in JCA model is determined via finite element analysis for the hexagonal micro-structure. Moreover, a mathematical model is constructed to obtain the optimized micro-structure design, with fiber radius and gap as design parameters and average absorption performance of the porous fibrous material under set frequency band as target. Utilizing the constructed optimization model, the microstructure parameters are derived with optimal sound absorption under low frequency (20 ⩽ f < 500 Hz), medium frequency (500 ⩽ f < 2000 Hz) and high frequency (2000 ⩽ f < 15,000 Hz), respectively. On top of that, for a given thickness of porous fibrous material layer, the analytical relationship between fiber radius and optimal porosity under set frequency bands is constructed.     

Fast and wide-band response infrared detector using porous PZT pyroelectric thick film

Porous lead zirconate titanate (PbZr_0.3Ti_0.7O₃, PZT30/70) thick films and detectors for pyroelectric applications have been fabricated on alumina substrates by screen-printing technology. Low temperature sintering of PZT thick films have been achieved at 850 °C by using Li₂CO₃ and Bi₂O₃ sintering aids. The microstructure of PZT thick film has been investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dielectric properties were measured using HP 4284 at 1 kHz under 25 °C. The permittivity and loss tangent of the thick films were 94 and 0.017, respectively. Curie temperature of PZT thick film was 425 °C as revealed by dielectric constant temperature measurement. The pyroelectric coefficient was determined to be 0.9 × 10⁻⁸ Ccm⁻² K⁻¹ by dynamic current measurement. Infrared detector sensitive element of dual capacitance was fabricated by laser directly write technology. Detectivity of the detectors were measured using mechanically chopped blackbody radiation. Detectivity ranging from 1.23 × 10⁸ to 1.75 × 10⁸ (cm Hz^1/2 W⁻¹) was derived at frequency range from 175.5 Hz to 1367 Hz, and D^*’s −3 dB cut-off frequency bandwidth was 1.2 kHz. The results indicate that the infrared detectors based on porous thick films have great potential applications in fast and wide-band frequency response conditions.     

Effects of ultrasonic treatment on the maturation of Zhenjiang vinegar

High-quality vinegars are traditionally produced by aging them in barrels or bottles. However, these processes are very time-consuming. To accelerate of Zhenjiang vinegar maturation, the ultrasound was used to treat the steeped vinegar. Results showed that, the optimum ultrasonic power, time and ethanol addition for aging vinegar were determined to be 50 W/100 mL, 75 min and 0.75% (V/V), respectively. Under the optimum experimental conditions, the total amino acid of fresh vinegar decreased from 1082.259 mg/100 mL to 871.045 mg/100 mL. Several volatile components increased significantly, such as the total esters, aldehydes and heterocyclic. Total non-volatile organic acids increased from 202.59 mg/10 mL to 233.87 mg/10 mL. The changes of above-mentioned components develop towards the direction of mature vinegar. Coupling the HS-SPME/GC–MS analysis data with Principal Components Analysis, ultrasonic treatment vinegar was determined to be equivalent to 2–3 years of natural aged Zhenjiang vinegar. This study has showed that ultrasound is promising not only in shortening the aging time and lowering costs for the vinegar-making industry, but also in producing fine vinegar.     

Mechanistic study on ultrasound assisted pretreatment of sugarcane bagasse using metal salt with hydrogen peroxide for bioethanol production

This study presents the ultrasound assisted pretreatment of sugarcane bagasse (SCB) using metal salt with hydrogen peroxide for bioethanol production. Among the different metal salts used, maximum holocellulose recovery and delignification were achieved with ultrasound assisted titanium dioxide (TiO₂) pretreatment (UATP) system. At optimum conditions (1% H₂O₂, 4 g SCB dosage, 60 min sonication time, 2:100 M ratio of metal salt and H₂O₂, 75 °C, 50% ultrasound amplitude and 70% ultrasound duty cycle), 94.98 ± 1.11% holocellulose recovery and 78.72 ± 0.86% delignification were observed. The pretreated SCB was subjected to dilute acid hydrolysis using 0.25% H₂SO₄ and maximum xylose, glucose and arabinose concentration obtained were 10.94 ± 0.35 g/L, 14.86 ± 0.12 g/L and 2.52 ± 0.27 g/L, respectively. The inhibitors production was found to be very less (0.93 ± 0.11 g/L furfural and 0.76 ± 0.62 g/L acetic acid) and the maximum theoretical yield of glucose and hemicellulose conversion attained were 85.8% and 77%, respectively. The fermentation was carried out using Saccharomyces cerevisiae and at the end of 72 h, 0.468 g bioethanol/g holocellulose was achieved. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis of pretreated SCB was made and its morphology was studied using scanning electron microscopy (SEM). The compounds formed during the pretreatment were identified using gas chromatography–mass spectrometry (GC–MS) analysis.