Technology and equipment for hydrostatic treatment of materials

Abstract

The main requirements of the quality of products are the homogeneity of technological and service properties, the improved characteristics of strength and plasticity, endurance and brittle failure resistance. In recent years many investigations into developing the High Hydrostatic Pressure Technologies (HHPT) and equipment to meet these requirements have been carried out by scientific schools of Academicians, L. F. Vereshchagin, G. V. Kurdyumov, A. I. Tselikov and A. A. Galkin in the USSR. The physical basis of these technologies is represented by the plastic deformation effects under high pressure: material plasticization’, strain ageing², decrease of a carbide inhomogeneity³, use of a liquid as a machining tool⁴ etc. HHPT are widely spread and especially promising in metallurgy as the ferrous metals account for more than 96% of the total structural material consumption in machine building, while assortment of products is about 5000 profile sizes of bars, 30 000 profile sizes of tubes, 50 000 types of metalware.     

Structure of self-implanted silicon annealed under enhanced hydrostatic pressure

Implantation of any ions at a sufficiently high dose and energy (E) into single-crystalline Si leads to the creation of amorphous Si (aSi), with damages peaking near the projected range (R _p) of implanted species. Enhanced hydrostatic pressure (HP) at a high temperature (HT) influences the recrystallization of aSi. The structure of self-implanted Czochralski silicon (Si⁺ dose, D=2×10¹⁶ cm^?2, E=150 keV, R _p=0.22 μm) processed for 5 h at 1400 or 1520 K under HPs up to 1.45 GPa was investigated by X-ray, secondary ion mass spectrometry and photoluminescence methods. The implantation of Si produces vacancies (V) and self-interstitials (Si_i). Vacancies and Si_is form complex defects at HT–HP, also with contaminants (e.g. oxygen, always present in Czochralski silicon). The mobility and recombination of V and Si_i as well as the kinetics of recrystallization are affected by HP, thus processing at HT–HP affects the recovery of aSi.     

Use of pulsed-high hydrostatic pressure treatment to decrease patulin in apple juice

This study was aimed at reducing patulin content of apple juice using a non-thermal method, namely pulsed-high hydrostatic pressure (p-HHP). Commercially available clear apple juice was contaminated artificially with different concentrations of patulin (5, 50 and 100?ppb). Then, the samples were processed 5?min at different pressure treatments (300–500?MPa) in combination with different temperatures (30–50°C) and pulses (6 pulses?×?50?s and 2 pulses?×?150?s). To compare the impact of pulses, single pulse of high hydrostatic pressure (HHP) treatment was also applied with the same pressure/temperature combinations and holding time. Results indicated that pressure treatment in combination with mild heat and pulses reduced the levels of patulin in clear apple juice up to 62.11%. However, reduction rates did not follow a regular pattern. p-HHP was found to be more effective in low patulin concentrations, whereas HHP was more effective for high patulin concentrations. To the best of our knowledge, this is the first study using p-HHP to investigate the reduction of patulin content in apple juice.     

X‐ray reflectivity measurements of liquid/solid interfaces under high hydrostatic pressure conditions

A high‐pressure cell for in situ X‐ray reflectivity measurements of liquid/solid interfaces at hydrostatic pressures up to 500 MPa (5 kbar), a pressure regime that is particularly important for the study of protein unfolding, is presented. The original set‐up of this hydrostatic high‐pressure cell is discussed and its unique properties are demonstrated by the investigation of pressure‐induced adsorption of the protein lysozyme onto hydrophobic silicon wafers. The presented results emphasize the enormous potential of X‐ray reflectivity studies under high hydrostatic pressure conditions for the in situ investigation of adsorption phenomena in biological systems.     

Study of semiconductor lasers under simultaneous uniaxial stress and hydrostatic pressure

Abstract

We present the design of a device for the simultaneous application of uniaxial stress and hydrostatic pressure. This new apparatus will for the first time allow measurements at constant strain. Results of the simultaneous application of uniaxial stress and hydrostatic pressure to a semiconductor laser are presented and discussed.     

Clarification of the recovery mechanism of Escherichia coli after hydrostatic pressure treatment

High hydrostatic pressure (HP) technology has gained more attention as a non-thermal food pasteurization technology. Recently, a limitation of the HP technology was reported by Koseki and Yamamoto [Recovery of Escherichia coli ATCC 25922 in phosphate buffered saline after treatment with high hydrostatic pressure. Int. J. Food Microbiol. 2006;110:108–111], who completely recovered Escherichia coli species after HP treatment. We investigated the recovery mechanism of E. coli after HP treatment. The cells were treated with 200–300 MPa at 0–25°C for 24 h. The HP-treated E. coli was recovered in phosphate-buffered saline (PBS) during 120 h of incubation at 25°C, confirming the results reported by them. However, E. coli did not grow in PBS but grew with inactivated cells in PBS. In addition, the results of our “population size experiments” demonstrated that the recovery of E. coli cells depended on both the degree of pressure and the population size. These results suggest that some portion of cells recovered from the damage and then grew by using inactivated cells.     

A martensitic phase transition in nanocrystalline 3Y-TZP powders under hydrostatic pressure conditions

The aim of this study was to produce yttria-stabilized zirconia nanopowders from zirconium oxychloride and zirconium oxynitrate salts using a co-precipitation technique, and to investigate the influence of hydrostatic pressure on the phase transition in these powders. It is shown that synthesis conditions and calcination temperature have a strong influence on the nanopowder's agglomeration, as well as on the stability of the tetragonal phase to phase transition under pressure conditions. Doped zirconia nanopowders synthesized from oxynitrate salts are more agglomerated and more stable than the oxychloride-based powders. Increasing the role of interfacial energy in agglomerated nanopowders leads to an increase in the stability of the tetragonal phase in doped zirconia nanopowders systems obtained at low and high calcination temperatures. Formation of separated nanoparticles at middle calcination temperature leads to a decrease in the stability of the tetragonal phase to phase transition under hydrostatic pressure conditions.     

Structure ortimization of two-phase titanium alloy by way of hydrostatic extrusion

Abstract

Two-phase titanium alloy was deformed up to 50% by hydrostatic pressure. Deformation combined with various schemes of heat treatment sufficiently changes morphology and internal structure of all constitutent alloy phases. Structural changes cause improvement of mechanical properties.     

Structural and electronic properties of carbon nanotubes under hydrostatic pressures

We studied the structural and electronic properties of carbon nanotubes under hydrostatic pressures based on molecular dynamics simulations and first principles band structure calculations. It is found that carbon nanotubes experience a hard-to-soft transition as external pressure increases. The bulk modulus of soft phase is two orders of magnitude smaller than that of hard phase. The band structure calculations show that band gap of (10, 0) nanotube increases with the increase of pressure at low pressures. Above a critical pressure (5.70GPa), band gap of (10, 0) nanotube drops rapidly and becomes zero at 6.62GPa. Moreover, the calculated charge density shows that a large pressure can induce an {sp}²-to-{sp}³ bonding transition, which is confirmed by recent experiments on deformed carbon nanotubes.     

Effect of high hydrostatic pressure processing and squeezing pressure on some quality properties of pomegranate juice against thermal treatment

The aim of this study was to investigate the effect of high hydrostatic pressure (HHP) treatment (200, 300, 400?MPa; 5°C, 15°C and 25°C; 5 and 10 min) on some quality properties of pomegranate juice. Juice samples are obtained under industrial conditions at two different squeezing pressure levels (100 and 150?psi – 0.689 and 1.033?MPa, respectively). Results are compared against conventional thermal treatment (85°C/10 min) and raw sample. For all three processing temperature, HHP combinations at 400?MPa for 10 min were sufficient to decrease the microbial load around 4.0 log cycles for both squeeze levels. All HHP treatments showed no significant decrease at antioxidant activity, total phenolic content and monomeric anthocyanin pigment concentrations, while there was a significant decrease (p?≤?.05) in thermal-treated samples. Being the highest sugar alcohol in pomegranate juice, mannitol content must be considered for determining the authenticity, and mannitol content increased with squeezing pressure and thermal treatment.     

Nitrogen-induced band formation in GaNxAs1−x studied by photoluminescence under hydrostatic pressure and photomodulated reflectance

Abstract

GaN_xAs_1?x samples with × ranging from 0.043% to 2.8% were grown by MOVPE. Analysing low-temperature photoluminescence spectra taken under hydrostatic pressure and room temperature photomodulated reflectance spectra gives strong evidence that the transition from N acting as an isoelectronic impurity to forming N-induced bands takes place at a N-concentration of about 0.2%.     

圆柱形超高静水压水听器设计与测试

(本文介绍了一种应用于20Hz~20kHz频段、最大工作深度5000米的超高静水压水听器,水听器敏感元件采用厚壁压电陶瓷圆管,高强度复合泡沫去耦,通过对敏感元件及水听器结构进行合理设计,保证水听器具有高的耐压强度。设计了一种圆柱形高静压耦合腔,根据耦合腔声学和力学条件,确定了腔体尺寸及厚度,在国内首次实现了最高50MPa压力下的水听器低频灵敏度测试。测试结果表明,水听器常压下接收灵敏度响应平坦,在常压到50MPa压力范围内,水听器低频接收灵敏度最大变化小于2dB,表明该型水听器具有良好的压力稳定性,可在深海资源勘测、深海通讯等方面获得广泛应用。)     

Inactivation of Staphylococcus aureus using high hydrostatic pressure

The aim of this work was to develop a high-pressure decontamination and sterilization process for pharmaceutical treatments as was developed in food processing in the late eighties. The lack of normalized biological indicators able to validate sterilizing treatments under high pressure led us to select representative pathogenic strains from flora and the European Pharmacopoeia. We selected the following four bacterial strains: Candida albicans (ATCC 10231), Psuedomonas aeruginosa (ATCC 9027), spores of Aspergillus niger (ATCC 16404) and Staphylococcus aureus (ATCC 6538).

This present study is focussed on S. aureus. Successive pressurization and depressurization cycles appeared to be more efficient than a continuous high-pressure treatment. Importantly, these pressure conditions, temperature and process duration are perfectly compatible with current industrial plants. These results show that HHP technology is a new alternative to inactivate pathogenic strains in accordance with pharmaceutical requirements.     

Decrease in optical density as a results of germination of Alicyclobacillus acidoterrestris spores under high hydrostatic pressure

Alicyclobacillus acidoterrestris is a spore-forming bacterium, causing spoilage of juices. The spores of these bacteria have the ability to survive in the typical conditions used for thermal pasteurization. Therefore, the use of other techniques such as high hydrostatic pressure is considered for their inactivation. The effect of hydrostatic pressure of 200–500 MPa, at temperatures 4–50 °C for 15 min, on the dynamics of germination of A. acidoterrestris spores in apple juice and pH 4 buffer was studied. To estimate the share of germinated spores, the method of determining the optical density at a wavelength of 660 nm (OD₆₆₀) was used. Parameters of hydrostatic pressure treatment used in this work affected the dynamics of germination of A. acidoterrestris spores in apple juice, and the temperature had the greatest effect. The results indicate that nutrients present in apple juice can promote the germination of A. acidoterrestris spores.     

The usage of high hydrostatic pressure (HHP) to control food-borne pathogens in hummus

ABSTRACT

With the increasing demand for fresher, higher quality, minimally processed and safer food, there is a strong necessity to develop non-thermal processing techniques. Also for hummus, which is popular all around the world. In this work, the effect of refrigerated storage on the survival of pathogens in hummus treated by high hydrostatic pressure (HHP) (500?MPa/10?min/room temperature) was evaluated. The cocktail of two Salmonella, four Listeria monocytogenes and two Escherichia coli strains was used in this study. All pathogen types were able to survive in hummus during 60 days of refrigerated storage. HHP-treated samples plated on day 0 successfully achieved a?>?5 log cfu/g reduction for all pathogen types. No residual survivors were present after 30 and 60 days in any of the HHP-treated samples. These results demonstrate that HHP may be a useful technique for the inactivation of pathogens and therefore helpful in designing non-thermal HHP conditions for pressurization of hummus.     

Depletion of arginine in yeast cells decreases the resistance to hydrostatic pressure

High hydrostatic pressure (HP) inhibits growth and inactivates microorganisms by destabilizing non-covalent molecular interactions. Arginine contributes to stress resistance because it has a guanidine side chain, which assists in the refolding of aggregated proteins. We attempted to analyze the contribution of arginine to high HP stress using a pressure-sensitive mutant strain of Saccharomyces cerevisiae and a metabolomics approach. Our results showed that the content of 136 out of 250 detected metabolites differed in the mutant and parent strains. Decreased metabolites were involved in the tricarboxylic acid cycle and arginine biosynthesis. The expression of genes contributing to arginine biosynthesis was significantly lower in the mutant strain than in the parent strain. When arginine was supplemented to the medium, the mutant strain showed more tolerance to pressure. These results suggest that yeast cells survived due to the contribution of arginine to high pressure resistance. This indicates that depletion of arginine caused by decreased activity of the biosynthesis pathway confers sensitivity to HP.     

Listeria monocytogenes cells injured by high hydrostatic pressure and their recovery in nutrient-rich or -free medium during cold storage

ABSTRACT

Cells of Listeria monocytogenes suspended in phosphate-buffered saline (PBS) were treated by high hydrostatic pressure (HHP; 500?MPa, 25°C, 10?min), diluted by ten folds using trypticase soy broth (TSB) or PBS, and stored at cold temperatures of 0–15°C. Viable cell count in TSB increased logarithmically close to the initial count at each storage temperature, while that in PBS increased temporarily and subsequently decreased to almost nondetectable level except the case at 15°C, where it showed logarithmic increase thereafter. Based on proliferation experiments where their healthy cells were inoculated to TSB or to PBS containing their heat-killed dead cells, it was suggested that increase in the viable count of HHP-treated cells in TSB and PBS could be ascribed to the recovery of colony forming ability and/or proliferation depending on the cold storage temperature.     

The response of temperature and hydrostatic pressure of zinc-blende GaxIn1-xAs semiconducting alloys

<正>The electronic band structure of Ga_xIn_1-xAs alloy is calculated by using the local empirical pseudo-potential method including the effective disorder potential in the virtual crystal approximation.The compositional effect of the electronic energy band structure of this alloy is studied with composition x ranging from 0 to 1.Various physical quantities such as band gaps,bowing parameters,refractive indices,and high frequency dielectric constants of the considered alloys with different Ga concentrations are calculated.The effects of both temperature and hydrostatic pressure on the calculated quantities are studied.The obtained results are found to be in good agreement with the available experimental and published data.     

Effect of high hydrostatic pressure and high dynamic pressure on stability and rheological properties of model oil-in-water emulsions

Both static and dynamic high pressure applications provide interesting modifications in food structures which lead to new product formulations. In this study, the effects of two different treatments, high hydrostatic pressure (HHP) and high dynamic pressure (HDP), on oil-in-water emulsions were identified and compared. Microfluidization was selected from among the HDP homogenization techniques. The performance of each process was analyzed in terms of rheological modifications and emulsion stability improvements compared with the coarse emulsions. The stability of the emulsions was determined comparatively by using an analytical photo-centrifuge device employing novel analysis technology. Whey protein isolate (WPI) in combination with a food polysaccharide (xanthan gum, guar gum or locust bean gum) were used as emulsifying and stabilizing ingredients. The effective disruption of oil droplets and the degradation of polysaccharides by the shear forces under high pressure in HDP microfluidization yielded finer emulsions with lower viscosities, leading to distinctive improvements in emulsion stability. On the other hand, improvements in stability obtained with HHP treatment were due to the thickening of the emulsions mainly induced by protein unfolding. The corresponding increases in viscosity were intensified in emulsion formulations containing higher oil content. Apart from these, HHP treatment was found to be relatively more contributive to the enhancements in viscoelastic properties.     

Structural and kinetic aspects of hydrostatic pressure effect on polymer network formation

Abstract

Effect of hydrostatic pressure up to 250 MPa on structurization kinetics and morphology of network polymers based on epoxy oligomers has been studied using the methods of measurements of volume resistivity and optical microscopy.