PV Value Research Articles

Development and characterization of a 140-element MEMS deformable mirror

For satisfying the boarder application requirement of adaptive optics (AO) and solving the problem of large volume and high cost of conventional deformable mirrors (DM), micro DM based on micro-electro-mechanical system (MEMS) technology is developed and measured. The developed DM has 140 hexagonal parallel plate capacitor electrostatic actuators. The actuators are arranged as a square array and the pitch is 400 μm. A DM prototype is fabricated by MEMS surface micromachining process and packaged by a ceramic pin grid array (CPGA). A miniaturization multi-channel high voltage driver for the DM is developed too. The measurement results show that the prototype has a surface PV value of 411 nm, RMS value of 78 nm, reflectivity of about 80% in 600 nm to 900 nm wavelength, stroke of 1.8 μm, actuator coupling of 15%, working bandwidth of 13 kHz and step response time of 23 μs. Thus the DM has the advantages of small volume, low cost and fast response. Besides the measurement of single element, the whole DM is controlled open loop to fit Zernike aberration and its fitting capability is demonstrated. Above results indicate that the DM prototype can satisfy initially the requirement of AO system.

Study on Surface Morphology of Vibration Assisted Cutting

Vibration assisted cutting is widely regarded as an effective technique due to the characteristics of friction reversal and intermittent cutting. However, there are few studies on surface morphology of vibration assisted cutting machining. The high frequency error (surface roughness) and low frequency error (surface error) of the surface topography are obtained by the decomposition and reconstruction of the wavelet packet in this paper for the in-depth investigating of the surface morphology. The influence of vibration assisted cutting parameters on surface topography are revealed by calculating the surface evaluation parameters such as surface roughness, PV value and root mean square error. In this paper, two-dimensional wavelet packet analysis is conducted on the surface morphology of vibration assisted cutting. Finally, the influence of surface roughness and shape error on vibration assisted cutting are obtained. Through the analysis, it can be found that, along with the increase of the minor axis of vibration assisted cutting parameters, the surface roughness, PV value and root mean square deviation become larger during the processing.

Polishing technique for potassium dihydrogen phosphate crystal based on magnetorheological finishing

Potassium dihydrogen phosphate (KDP) crystal is an extremely valuable and irreplaceable nonlinear optical crystal that is widely used as frequency converter and electric-optical switch in various areas such as inertial confinement fusion (ICF) laser systems. However, it is very difficult to machine KDP crystals because they are thermally sensitive, prone to fracture, hygroscopic and easily scratched. The typical process used for machining KDP crystals is single-point diamond turning (SPDT). Though ultra-precision flatness fly-cutting machines are employed to machine large-aperture KDPs, small-scale ripple errors persist, and the cutting accuracy is limited by machine tool imprecision. Magnetorheological finishing (MRF) has been developed for KDP crystal processing, but controlling the surface integrity of KDP crystal is a key associated problem, due to the low hardness of the crystal and water solubility. In this paper, a new type of oil-based magnetorheological fluid (MR fluid) is developed, and the removal mechanism for KDP crystals is studied. The roughness control and the defect-removing mechanism are also investigated. Using the MR fluid, surface integrity controlling techniques and other relevant technologies, a large-aperture KDP crystal is successfully polished. For a KDP crystal of 410 mm × 410 mm, PV value is greatly reduced from 4.36 λ to 1.32 λ, RMS from 0.698 λ to 0.138 λ and roughness is reduced to Rq 2 nm. Results show that large-aperture KDP crystal can be successfully polished by the MRF machine, indicating that the MR fluid designed has superior effectiveness, longer-term stability and an excellent surface integrity.

Population variability of three Delia species (Diptera: Anthomyiidae) from the same agricultural habitat in Québec, Canada

AbstractLong-term trap catches of seedcorn maggot, Delia platura (Meigen), onion maggot, Delia antiqua (Meigen), and cabbage maggot, Delia radicum (Linnaeus) (Diptera: Anthomyiidae), were used to test the hypothesis that related species have more similar population variability than unrelated ones. Annual abundance was estimated from trap catches for 32 years (two species) or 17 years (one species). Population variability was quantified as PV, a proportion between 0 and 1. The three Delia Robineau-Desvoidy species had PV values of 0.51–0.55 that did not differ significantly. These PV values were found to differ significantly from two unrelated species studied over the same time period in the same habitat, which had PV values of 0.39 and 0.67. The hypothesis that related species have more similar population variabilities than unrelated species in the same habitat was supported. These data strengthen the view that PV is a species-specific trait reflecting the adaptation of life histories to their habitat, with related species showing more similar adaptations than unrelated species. The polyphagous and saprophagous seedcorn maggot had PV similar to the two oligophagous herbivores, casting doubt on the hypothesis that more generalist feeders have less variable populations than more specialised feeders.

Effect of chitosan and acetic acid on the shelf life of sea bass fillets stored at refrigerated temperature

Considering the necessity on the use of chitosan and acetic acid as an antimicrobial and antioxidant agents, an attempt was made to study their effect on Asian sea bass fillets stored at refrigerated temperature of 4±1°C. The effectiveness of different antimicrobials (Chitosan and Acetic acid) were measured by disk diffusion method against five bacterial strains (E. coli, Vibrio parahaemolyticus, Staphylococcus aureus, Proteus mirabilis and Pseudomonas fragi) with 1% Acetic acid as (T1), 1% Acetic acid + 1% Chitosan as (T2), 1% Acetic acid + 2% Chi-tosan as (T3) and distilled water as control (C).T2 was more effective in inhibiting all the bacteria except Pseudomo-nas fragi. Treatment T1 was found to be more effective against it whereas the action of T3 on the bacterial strains was also effective but less than the other two treatments. Further, antioxidant property of the treatments were measured by DPPH method which indicated that T3 showed highest % of antioxidative activity (3.94%) followed by T1 (3.85%), T2 (2.62%), and C (1.788%).Thus, it is observed that the antioxidant activity was found to be increased with the increasing concentration of chitosan. Application of chitosan and acetic acid coatings on Asian sea bass ( Lates calcarifer) fillets successfully controlled the TVB-N values, PV and TBA values (p<0.05) when compared to control sample and among all the treatments T2 was found to be the best. Coating of chitosan and acetic acid on the fillets also resulted in improvement of sensory scores as well as acceptability under refrigerated condition.

Thin-Walled Double Side Freeform Component Milling Process with Paraffin Filling Method

The machining of thin-walled double side freeform component has many challenges in terms of the geometrical complexity, high-requirement accuracy, and especially low stiffness. This paper surveys the filling method during the milling processes of thin-walled double side freeform component. Firstly, the DEFORM-3D was used to analyze and calculate the surface residual stress which provides a theoretical basis for parameters selection of the rough milling process, and the optimal milling parameters were obtained by the Taguchi method. Residual stress measurements have been carried out to verify the simulation results. The results show the difference between simulation and experimental data is less than 15%. Secondly, semi-finishing parameters and finishing process parameters were determined by equal error step length and step distance method. Thirdly, two machining experiments were conducted with and without paraffin filling, and the accuracy was measured by coordinate measurement machine. The results shown that the PV values are 25.16 μm and 20.34 μm for the concave and convex surface, and the corresponding RMS values are 13.75 μm and 11.93 μm in the first milling experiment. The PV values have improved to 8.53 μm and 7.12 μm, and RMS values have improved to 2.45 μm and 3.05 μm by the filled method applied.

Harvesting energy from leachates in microbial fuel cells using an anion exchange membrane

The aim of this work was to evaluate the performance of a single chamber microbial fuel cells (SC-MFCs) equipped with an anion exchange membrane, Zirfon membrane (ZF) with actual leachate as substrate, in terms of the volumetric power (PV) delivered and chemical oxygen removal efficiency (ηCOD). The SC-MFCs were loaded with three different mixtures of leachate with sulphate-reducing inocula (SR-I) as biocatalyst: 30% leachate + 70% SR-I (Period I); 70% leachate + 30% SR-I (Period II) and 50% leachate + 50% SR-I (Period III).From the start of the operation of the SC-MFC equipped with ZF, the PV values shown were encouraging: 4260 and 8050 mW m−3 for Periods I and II, respectively. Finally, in the Period III, the PV reached was up to 10 380 mW m−3, whereas the SC-MFC fitted with Nafion 117 membrane (NF) used as reference, delivered a substantially lower PV of only 104 mW m−3.In conclusion, membrane type played a significant role: the SC-MFC fitted with ZF in terms of PV outperformed the SC-MFC fitted with NF. The proportion of leachate and inoculum seemed to have a positive effect on the power delivery of only the MFC equipped with ZF, likely related to increased organic matter availability with increased concentration of leachate.

The enhancement of pistachio green hull extract functionality via nanoliposomal formulation: studying in soybean oil.

Phenolic compounds of pistachio green hull extract (PGHE) were incorporated into nanoliposomes (NLs). The NLs were prepared with different concentrations of phenolic compounds of PGHE (500, 750 and 1000ppm) and particle size, polydispersity index (PDI), zeta potential and encapsulation efficiency (EE) were investigated. The antioxidant activity of free and incorporated phenolic compounds of PGHE were evaluated in soybean oil during 39days of storage by measuring peroxide (PV), thiobarbituric acid (TBA) values and color. The total phenolic content and IC50 (DPPH assay) of PGHE were 614.91±0.45mg gallic acid equivalent/g fresh weight of extract and 10±0.05μg/ml extract, respectively. The prepared NLs had 101.86-105.81nm size and PDI=0.202-0.235. The zeta potential value of NLs varied between -47.7 and -52.3mV. The highest EE (32.47%) was observed for NLs containing 1000ppm of phenolic compounds. The lowest PV and TBA values were related to free phenolic compounds at 500mg/kgoil. In comparison with free phenolic compounds, loaded NLs had lower antioxidant activity, but encapsulation could improve the stability, gradual release and solubility of phenolic compounds in soybean oil. The color of NLs containing oil samples remained constant during the storage, but free phenolic compounds changed the oil`s color. All concentrations of free and incorporated phenolic compounds had also higher antioxidant activity than BHT. Finally, 500ppm of phenolic compounds of PGHE in its incorporated forms could be recommended as a substitute for synthetic antioxidant in soybean oil.

Assessment of Shelf Lives of Black Pepper and Small Cardamom Cookies by Metal Oxide-Based Electronic Nose Using Spoilage Index

E-nose technology has been successfully employed in determination of rancidity in nutraceutical-rich drop cookies. The cookies were formulated with extracts obtained by supercritical carbon dioxide extractions and post-extraction sample matrices of black pepper and small cardamom. Rancidity in cookies was estimated by comparing the odor profiles of stored cookies with the profiles of deliberately rancid cookies (training sets), using e-nose. PCA plots along with spoilage indices obtained from Mahalanobis distances calculated from e-nose responses revealed that the extracts and post-extraction sample matrices of these spices performed as natural antioxidants in preventing rancidity in cookies. Both the extracts enhanced the shelf lives of cookies by at least 120 days; post-extraction matrices of black pepper and small cardamom enhanced the same by 80 and 40 days, respectively. These findings were further affirmed by biochemical analyses and linear regression equations were generated for prediction of FFA content, PV, and MDA values from the spoilage indices of each type of cookie. Thus, spoilage indices can circumvent the requirement of conducting cumbersome biochemical assays for estimation of rancidity in cookies. Similar applications of e-nose technology and spoilage indices can be envisaged for other bakery products also.

Research on wavefront properties of high power frequency tripling lasers based on type II/II KDP crystals

The relationship between the output frequency tripling (3ω) wavefront and the input fundamental laser (1ω) wavefront is researched in theory and experiment in the frequency conversion process based on type II/II KDP (KH2PO4) crystals. Theoretical results show the output 3ω wavefront distortion is three times of the input 1ω wavefront distortion on the phase-matching condition. The output 3ω and 1ω wavefront are measured by Hartman wavefront sensor in the high power frequency tripling laser system. Experimental results show that the output 3ω wavefront PV value is 2.97 times of the 1ω wavefront value and the output 3ω wavefront RMS value is 3.57 times of the 1ω wavefront value. Therefore, the theoretical relationship between the output 3ω wavefront and the input 1ω wavefront in the frequency conversion system is proved correct within the range of permitted experimental errors.

Dynamic characteristics and transient sealing performance analysis of hyperelliptic curve groove dry gas seals

This paper puts forward dry gas seals with novel face grooves that are called as hyperelliptic curve grooves. At high PV value, gas film dynamic characteristic coefficients isoline distributions are obtained under the different polar angle and hyperelliptic coefficient. Disturbance behaviors of gas film thickness and pressure are studied whether there is angular excitation or not. Saltation peak and period peak are defined, and their isoline distributions are presented which reveal the influence mechanism of gas film dynamic characteristics coefficients on dynamic tracking property. A dynamic wedge-shaped gap with a fixed angle between seal faces will form under the influence of angular excitation, and it has a significant impact on transient behaviors of the dry gas seals.

Adaptive aberration correction of a 5 J/66 ns/200 Hz solid-state Nd:YAG laser

In this Letter, we present an adaptive aberration correction system to simultaneously compensate for aberrations and reshaping the beams. A low-order aberration corrector is adapted. In this corrector, four lenses are mounted on a motorized rail, whose positions can be obtained using a ray tracing method based on the beam parameters detected by a wavefront sensor. After automatic correction, the PV value of the wavefront is reduced from 26.47 to 1.91μm, and the beam quality β is improved from 18.42 to 2.86 times that of the diffraction limit. After further correction with a deformable mirror, the PV value of the wavefront is less than 0.45μm, and the beam quality is 1.64 times that of the diffraction limit. To the best of our knowledge, this is the highest performance from such a high-power, high-pulse repetition rate Nd:YAG solid-state laser ever built.

Utilization of Faba Bean Hulls (Seeds Coat )as a Source to Produce Antioxidants

The current research investigates the opportunity of using Faba bean hulls (seeds coat) for producing some bioactive compounds such as natural antioxidants using several solvents, and to investigate the stability of edible oil with phenolic extract against oxidative rancidity compared with other containing (BHA) during heat at 180°C for one day. The results show that ethanol gave the highest yield extract and polyphenol content. Then it yields methanol, chloroform and water. The HPLC analysis is executed. It provides the total polyphenols extracted from faba bean. Thehulls were indicated to the existence of high Pyrogallol, e-Vanillic, Ellagic and Catechin percentages. Also, the results showed that oils which treated by the extract at varied concentrations have PV and TBA values lower than control.

Effect of severing skeletal muscle at different stage of rigor on the quality of pacific white shrimp (Litopenaeus vannamei)

Effect of severing skeletal muscle (by beheading) at different stages of rigor on the quality of pacific white shrimp (Litopenaeus vannamei) during ice storage was assessed by physical, chemical, and sensory evaluation. Shrimps were divided into three lots, one lot (T1) beheaded immediately after killing, 2nd (T2), and 3rd (T3) lots were beheaded after 5 h and 35 h post-mortem corresponding to pre-rigor, in-rigor, and post-rigor stages, respectively. There was an increase in the moisture content in all the treatments during the storage. PV, TVB-N, and TMA-N values also increased with the storage time, though the values of all these parameters were well within the acceptable limits. Total protein, Sarcoplasmic protein, NPN, and water holding capacity showed a decreasing trend in all the treatments. Hardness, springiness, cohesiveness and chewiness values did not differ significantly (p ≤ .05) between the treatments. L* value showed a decreasing trend throughout the study. Information provided in this study can serve as baseline for postharvest preservative treatments of crustacea products. Practical applications This work examined the effect of the time of beheading on the quality of shrimps in ice storage. No work ever looked at the possibility of whether the quality of shrimp varies if its skeletal muscle is severed (by beheading) during pre-rigor, on-rigor, and post-rigor stages. The ice storage studies of three lots demonstrated similar deterioration of quality, without significant differences among the lots. This strongly suggests that the transportation of the whole shrimps to a processing factory at a distant site provides no comparative advantage in terms of quality.

Effect of lavender and lemon balm extracts on fatty acid profile, chemical quality parameters and sensory quality of vacuum packaged anchovy (Engraulis encrasicolus) fillets under refrigerated condition

The impact of natural plant extracts on chemical parameters, fatty acid profile and sensory properties of vacuum packed anchovy was investigated refrigerated condition (2±1 °C). The anchovy fillets were separated into three groups; which were immersed in 1% French lavender (FL) or lemon balm (LB) extract and the control (C) without plant extract. Along with sensory analysis, the shelf-life of anchovies was 7 days for control and 11 days for both treated extracts. At the end of the storage period, the higher PUFA and omega-3 values were found as 24.43%, 30.97% and 27.88% for C group, FL and LB treatments, respectively. In addition, at the limit of acceptability, TVB-N values reached 41.17 mg/100 g for C group (7 days), 37.42 mg/100 and 42.86 mg/100 g for FL and LB batches (9 days), respectively. Lower PV and TBA values were observed in the fish fillets that treated the LB extract comparison with the other groups (P ≤ 0.05). Among samples, the application of plant extract caused lower value of FFA and pH compared to control group. These results suggest that treatment with FL and LB extracts prevents development of lipids oxidation and reduces the TVB-N values in anchovy's fillets resulting in shelf-life extension.

Volatile compounds and other indicators of quality for cold‐pressed rapeseed oils obtained from peeled, whole, flaked and roasted seeds

Cold‐pressed rapeseed oil is among the most popular virgin oils. Different processing methods yield oils varying in chemical composition and oxidative stability. The experiment aimed at identifying the differences (mostly in volatiles) between rapeseed oil obtained from peeled seeds (RO) and oils obtained by three pre‐treatment methods: pressing whole seeds (WSO), flakes (FO) and roasted flakes (RFO). Volatiles were analysed using GCxGC‐ToFMS and data were processed using statistical multivariate analysis. Fatty acid composition was determined using GC‐FID. The oils’ oxidative stability was measured using peroxide value. Free fatty acids’ value, absorbance at 236 and 238 nm and chlorophyll content were also determined. Also, a sensory panel evaluation was performed. PCA was found to be effective tool for differentiating the oils on the basis of their volatile compounds. RO was most similar to WSO from the second pressing. Fatty acid composition analysis yielded differences between the experimental oils and RO. RO had the highest PV, p‐AV and Totox values. WSO from the first pressing (WSO1) had the highest oxidative stability. Sensory analysis found that WSO1 was most similar to RO. Both oils had an intense cabbage‐like and fruity odour. The study showed that the results of volatile compounds’ analysis differs from those of sensory analysis in oils comparison.Practical applications: The results demonstrate that the rapeseed oil obtained from whole seeds may have a volatile compounds composition that is similar to that of rapeseed oil obtained from peeled seeds. PCA makes it possible to differentiate between samples varying in pre‐treatment method as well as between samples subjected to the same pre‐treatment method, but obtained from a second pressing. Sensory panel performed by trained panellists may demonstrate which oils are most desirable when rated for selected attributes. The results of sensory panel may differ from those of volatile compound analysis performed with GCxGC‐ToFMS.In the current study, the volatile compounds in cold‐pressed rapeseeds oil obtained from peeled seeds with those in rapeseed oils obtained from seeds prepared with various pre‐treatment methods are compared. The obtained results are compared with those of sensory evaluation. The study shows that the results obtained by means of statistical analysis based on volatile compounds do not always correlate with those of sensory panel evaluation in oils comparison.

Fermentation of sarshir (kaymak) by lactic acid bacteria: antibacterial activity, antioxidant properties, lipid and protein oxidation and fatty acid profile.

The antioxidant and antibacterial activities of fermented sarshir (traditional dairy food), with three probiotic Lactobacillus plantarum strains (LP3, AF1, and LU5), were investigated. The oxidative stability and the lipid profile of non-fermented and fermented sarshir were compared, in addition to radical scavenging activity, as well as peroxide, anisidine and carbonyl values (PV, AnV and CV, respectively). The strong antibacterial activity of fermented sarshir against common pathogenic bacteria, including Gram-negative Escherichia coli O157: H7 ATCC 35150 and Pseudomonas aeruginosa ATCC 27853, as well as Gram-positive Bacillus cereus ATCC 10876 and Staphylococcus aureus ATCC 25923, was established. Among the strains examined, L. plantarum LP3 exhibited the highest radical scavenging activity (53.1 ± 1.8%) and lowest PV (3.0 meq kg-1 ), AnV (1.31 ± 0.06) and CV (1.4 ± 0.08). The pH of sarshir decreased from 6.2 ± 0 to 3.5 ± 0.1 during 14 h of fermentation. Incorporated bacterial cells exhibited notable viability during 10 days of cold storage (4 °C). The fermentation of sarshir by L. plantarum strains, especially LP3, resulted in beneficial changes in radical scavenging activity, as well as PV, AnV and carbonyl values, in addition to a broad spectrum of inhibitory activity against strains of P. aeruginosa, E. coli O157:H7, B. cereus and S. aureus. © 2017 Society of Chemical Industry.

Thermal optics property study and athermal design on optical window of IR aiming device reliability testing system

Optical window is used as optical interface connecting the reliability texting system for infrared aiming device with external infinite infrared simulation target which runs in acute axial temperature field, excellent thermal optics performance of optical window is the fundamental guarantee for testing system being in normal operation. In order to decrease the deformation of mirror surface caused by thermal stress, an athermal design decreasing thermal stress of optical window is put forward, a mathematical model of the deformation of optical window under axial temperature load is established and rigid body displacement after thermal deformation is analyzed by means of finite element method, the mirror surface is fitted by Zernike polynomial and introduced into optical analysis software to provide the analysis result of image quality and luminance uniformity of optical system. The rigid body displacement of optical window after athermal design decreases 0.164mm, MTF keeps invariant basically at 20lp/mm special frequency, the PV value and RMS value of IR optical window is just 0.342λ and 0.043λ, and uniformity of exit beam is raised up more significantly than without athermal design. The ZYGO interferometer is adopted as testing equipment detecting surface shape error (PV/RMS) of optical parallel of IR optical window. The experimental results show that the simulation results are in good agreement with the experimental results.

The relationship between vacuum and hemolysis during catheter blood collection: a retrospective analysis of six large cohorts.

Blood collection through intravenous (IV) catheters is a common practice at emergency departments (EDs). This technique is associated with higher in vitro hemolysis rates and may even be amplified by the use of vacuum collection tubes. Our aim was to investigate the association of five different vacuum tubes with hemolysis rates in comparison to an aspiration system under real-life conditions and to propose an equation to estimate the amount of hemolysis, depending on the vacuum collection tube type. We retrospectively evaluated hemolysis data of plasma samples from our ED, where blood is drawn through IV catheters. Over the past 5 years, we compared 19,001 hemolysis index values amongst each other and against the respective vacuum pressure (Pv) of the collection tubes, which were used within the six observational periods. The highest hemolysis rates were associated with full-draw evacuated tubes. Significantly reduced hemolysis was observed for two kinds of partial-draw tubes. The hemolysis rate of one partial-draw blood collection tube was comparable to those of the aspiration system. Regression analysis of Pv and mean free hemoglobin (fHb) values yielded the formula fHb (g/L)=0.0082*Pv2-0.1143*Pv+ 0.5314 with an R2 of 0.99. If IV catheters are used for blood collection, hemolysis rates directly correlate with the vacuum within the tubes and can be estimated by the proposed formula. By the use of partial-draw vacuum blood collection tubes, hemolysis rates in IV catheter collections can be reduced to levels comparable with collections performed by aspiration systems.

Preparation of a Φ60 mm Nd:YAG transparent ceramic disk

A high quality Nd:YAG transparent ceramic disk (Φ60 mm×2mm) has been prepared by the solid-state reactive sintering technique, which was sintered satisfactorily at 1780°C for 20h. The high transparency of the sample has been assured by its pore-free microstructure and pure YAG phase composition with the in-line transmittances up to 84.5% at 1064nm and 82.5% at 400nm, respectively. The optical homogeneity of the disk was evaluated by the interference stripes with the PV and RMS values being 0.099λ and 0.013λ, respectively. The maximum output power of 2052W with the slope efficiency of 39.0% was obtained at 500Hz repetition rate. Results indicated that the Nd:YAG transparent ceramics could be a potential option for high power disk laser.