Search

HighlightsThe impact sensors protected by shells and integrated with process circuits were proposed.Simulations and collision tests were performed to optimize the structure of the sensor.Accessories that can improve sensors’ detection accuracy were proposed.Multi-grain impact tests in a laboratory showed the RMSEs of two sensors were less than 1.67%.Abstract. Impact sensors are widely used to detect grain loss in harvesters, and the impact sensors with array structure polyvinylidene fluoride (PVDF) films have been proven to significantly increase the detection efficiency. However, uneven sensitivity and clutters from non-impacted sensitive units seriously affect the detection accuracy. This article proposes a protective shell for the impact sensors with array structure PVDF films. To improve the performance of this kind of sensor, we optimized the structure through finite element simulations and particle impact tests. The vibration modes under three pasting methods of sensitive units were analyzed. The relationship between the hardness of the elastic layer and response performances was investigated. To suppress the clutters, a method of splitting the elastic layer was proposed. Then, we manufactured two optimized impact sensors with one layer and two crossed layers of PVDF films and tested their performances. The results demonstrated that the sensitivities of the gaps between the PVDF films are poor. But when excluding the gaps’ data, the two sensors can meet the detection requirement. Accessories were proposed based on that characteristic to prevent particles from colliding with the gaps. After assembling the accessory, multi-grain impact tests showed that the root-mean-square errors (RMSEs) of the impact sensors with one layer and two crossed layers of PVDF films were 1.67% and 1.63%, respectively. Keywords: Grain loss detection, Particle impact test, Protective shell, Sensor accessory, Structure optimization.

Impact sensors are widely used to detect grain losses in harvesters. Using polyvinylidene fluoride (PVDF) films as sensing elements is a promising way to improve sensor performance due to their high sensitivity, stability, and flexibility. However, the overlap of collision signals significantly reduces the accuracy of a sensor. To solve this problem, a novel impact sensor with two crossed PVDF films was designed and investigated. This sensor has two orthogonal layers of sensing elements that both respond to impacts, which creates positioning information for the impacts. Because of the sensor’s structure, a signal processing method was designed based on multisensor fusion theory. Tests were performed to verify the performance of the proposed impact sensor. The average signal-to-noise ratios (SNRs) for impacted PVDF films were 34.79 and 20.23 dB, respectively, for the upper and lower layers, while the average signal-to-clutter ratios (SCRs) for nonimpacted films were 21.90 and 10.05 dB, respectively. The sensor also has an extremely high detection efficiency of at least 1528 collisions per second and can identify particles that impact at the same time. Keywords: Grain loss detection, Impact sensors, Multisensor fusion, Particle impact tests, PVDF films.

Pulsed electric field (PEF) technology is a promising nonthermal processing techniques that can be utilized to inactivate microorganisms in liquid food with high-voltage PEF. Herein, a high-voltage solid-state switch consisting of 64 insulated gate bipolar transistors (IGBTs) connected in series was designed and developed for the PEF treatment. Regarding the unbalanced sharing of voltage in series-connected IGBTs, the resistor–capacitor–diode snubber circuit was specifically used and investigated in terms of model of parameters. Furthermore, using gate drivers and optic fiber, the driving circuit and protection circuit were designed and validated. A 50-kV isolation level power supply was built in order to provide 16 independent IGBT stacks with 24 V of power each. The results show that the developed switch works adequately a delay time of 380 ns with 35.8-kV voltage and 44.8-A current capacity. Moreover, the response time of the short-circuit protection is acceptable as well with a reaction time of under $7~\mu \text{s}$ . In conclusion, the switch designed for PEF treatment of liquid food performs within set parameters and is ready for pilot-scale processing capability.

The metal sealing performance of subsea X-tree wellhead connectors is crucial for the safety and reliability of subsea X-trees. In order to establish the theoretical relation between metal sealing ring’s contact stress and its structural parameters and working pressure, a mechanical analysis method for double-cone sealing of high pressure vessels is applied in analyzing the metal sealing ring under the condition of preload and operation. As a result, the formula of the unit sealing load for the metal sealing ring under operation with residual preload is shown in this paper, which ensures that the metal sealing ring has an excellent sealing effect and can prevent the metal sealing ring from yielding. Besides, while analyzing the sealing process of the metal sealing ring, the change rule of contact stress and working pressure is concluded here, putting forward that the structural parameters of the metal sealing ring are the major factors affecting the change rule. Finally, the analytical solution through theoretical analysis is compared with the simulation result through finite element analysis in a force feedback experiment, and both are consistent with each other, which fully verifies for the design and calculation theory on metal sealing ring’s contact stress and its structural parameters and working pressure deduced in this paper. The proposed research will be treated as an applicable theory guiding the design of metal seal for subsea X-tree wellhead connectors.

As a non-thermal technology, pulsed electric field (PEF) treatment can be utilized in food processing and bioengineering for the inactivation of microorganisms and quality-degrading enzymes, as well as the retention of health-related compounds and the extension of shelf-life. Development of kinetic models that fit the degree of microbial inactivation and the loss of food quality is important to improve the efficiency of PEF treatment. The current review aims to provide an overview of the kinetic models used by PEF for microbial inactivation in liquid foods. Kinetics modeling for the destruction of microorganisms, inactivation of enzymes, retention of health-related compounds, and extension of shelf-life are discussed. Additionally, the fitting accuracy of several models, as well as issues that need further investigation, are discussed to promote further understanding and the deployment of PEF technology.

In this study, frozen restructured whole apple and strawberry bars were manufactured by partial dehydration, using infrared (IR) heating, followed by restructuring and freezing. The objective of this investigation was to determine the effect of IR partial dehydration on the quality of restructured frozen apple and strawberry bars. Apples and strawberries were cut into 6-mm-thick slices before being dried at 50C to various moisture levels: from 89.0 to 75.3% for apples and from 92.7 to 75.3% (wet basis) for strawberries. IR drying reduced the moisture in the fruits quickly and caused partial degradation of total phenolic and vitamin C. However, the concentration of total phenolic and vitamin C significantly increased in the finished fruit bars due to the moisture removal. Both frozen apple and strawberry bars had desirable appearance and hardness when their water activities were below 0.97. PRACTICAL APPLICATIONS This research demonstrated a new processing method for manufacturing healthful frozen fruit bars by using infrared partial dehydration of sliced fruit slices, followed by restructuring and freezing.

DsbA, a thioredoxin superfamily member, introduces disulfide bonds into newly translocated proteins. This process is thought to occur via formation of mixed disulfide complexes between DsbA and its substrates. However, these complexes are difficult to detect, probably because of their short-lived nature. Here we show that it is possible to detect such covalent intermediates in vivo by a mutation in DsbA that alters cis proline-151. Further, this mutant allowed us to identify substrates of DsbA. Alteration of the cis proline, highly conserved among thioredoxin superfamily members, may be useful for the detection of substrates and intermediate complexes in other systems.

Background: There are few data on the prevalence of WHO transmitted drug resistance mutations (TDRs) that could affect treatment responses to first line antiretroviral therapy (ART) in Hunan Province, China. Objective: Determine the prevalence of WHO NRTI/NNRTI/PI TDRs in ART-naive subjects in Hunan Province by deep sequencing. Methods: ART-naive subjects diagnosed in Hunan between 2010-2011 were evaluated by deep sequencing for low- frequency HIV variants possessing WHO TDRs to 1% levels. Mutations were scored using the HIVdb.stanford.edu algorithm to infer drug susceptibility. Results: Deep sequencing was performed on samples from 90 ART-naive subjects; 83.3% were AE subtype. All subjects had advanced disease (average CD4 count 134 cells/mm 3 ). Overall 25.6%(23/90) of subjects had HIV with major WHO NRTI/ NNRTI TDRs by deep sequencing at a variant frequency level $1%; 16.7%(15/90) had NRTI TDR and 12.2%(11/90) had a major NNRTI TDR. The majority of NRTI/NNRTI mutations were identified at variant levels ,5%. Mutations were analyzed by HIVdb.stanford.edu and 7.8% of subjects had variants with high-level nevirapine resistance; 4.4% had high-level NRTI resistance. Deep sequencing identified 24(27.6%) subjects with variants possessing either a PI TDR or hivdb.stanford.edu PI mutation (algorithm value$15). 17(19.5%) had PI TDRs at levels .1%. Conclusions: ART-naive subjects from Hunan Province China infected predominantly with subtype AE frequently possessed HIV variants with WHO NRTI/NNRTI TDRs by deep sequencing that would affect the first line ART used in the region. Specific mutations conferring nevirapine high-level resistance were identified in 7.8% of subjects. The majority of TDRs detected were at variant levels ,5% likely due to subjects having advanced chronic disease at the time of testing. PI TDRs were identified frequently, but were found in isolation and at low variant frequency. As PI/r use is infrequent in Hunan, the existence of PI mutations likely represent AE subtype natural polymorphism at low variant level frequency.

Based on diverse situations of the flowline of subsea Christmas tree installation and its working conditions, a theoretical model for calculation of the flowline is proposed by taking comprehensive considerations of different influencing factors, such as water depth, temperature of petroleum and gasoline, and angles of the flowline. By using the ABAQUS software, a finite element model for the flowline operating in an oil field in South China Sea is developed for verification of the proposed theory. The analysis and calculation present the variation of the thermal stress with different water depth, different oil & gas temperature and different bending angle of the flowline, and provid a theoretical support for the appropriate bending angle design of the flowline in the specific fields.

We describe the further utilization of a genetic screen that identifies mutations defective in the assembly of proteins into the Escherichia coli cytoplasmic membrane. The screen yielded mutations in each of the known genes encoding components of the E. coli signal recognition particle pathway: ffh , ffs , and ftsY , which encode Ffh, 4.5S RNA, and FtsY, respectively. In addition, the screen yielded mutations in secM , which is involved in regulating levels of the SecA component of the bacterium’s protein export pathway. We used a sensitive assay involving biotinylation to show that all of the mutations caused defects in the membrane insertions of three topologically distinct membrane proteins, AcrB, MalF, and FtsQ. Among the mutations that resulted in membrane protein insertion defects, only the secM mutations also showed defects in the translocation of proteins into the E. coli periplasm. Genetic evidence suggests that the S382T alteration of Ffh affects the interaction between Ffh and 4.5S RNA.

The active-site cysteines of DsbA, the periplasmic disulfide-bond-forming enzyme of Escherichia coli , are kept oxidized by the cytoplasmic membrane protein DsbB. DsbB, in turn, is oxidized by two kinds of quinones (ubiquinone for aerobic and menaquinone for anaerobic growth) in the electron-transport chain. We describe the isolation of dsbB missense mutations that change a highly conserved arginine residue at position 48 to histidine or cysteine. In these mutants, DsbB functions reasonably well aerobically but poorly anaerobically. Consistent with this conditional phenotype, purified R48H exhibits very low activity with menaquinone and an apparent Michaelis constant ( K m ) for ubiquinone seven times greater than that of the wild-type DsbB, while keeping an apparent K m for DsbA similar to that of wild-type enzyme. From these results, we propose that this highly conserved arginine residue of DsbB plays an important role in the catalysis of disulfide bond formation through its role in the interaction of DsbB with quinones.