Cavity Surface Research Articles

Numerical investigation on flow and aerothermal characteristics of rarefied hypersonic flows over slender cavities

Flow and aerothermal characteristics of rarefied hypersonic flows passing through slender cavities are investigated comprehensively using the direct simulation Monte Carlo (DSMC) method by various cases, such as the cavity with different depth-to-width ratios and different inclination angles, and the freestream at different altitudes and Mach numbers. The cavity depth-to-width ratio has a great influence on flow structures and gas density inside the cavity, but a slight effect on gas temperature inside the cavity and on heat flux over cavity surfaces. In comparison to the vertical cavity, the upstream-inclined cavity reduces the gas density and the high-temperature area inside the cavity, showing a decrease rate of gas density of about 53 % for φ = -45°, while the downstream-inclined cavity greatly raises the gas density and slightly expands the high-temperature area, reaching a growth rate of gas density of about 114 % for φ = 45°. As the freestream altitude increases from 50 to 80 km, the main vortex expands remarkably while the heat flux near the top of the aft wall decreases sharply, and a noteworthy finding is that the dimensionless temperature contours inside the cavity for the cases of H = 50, 60, and even 70 km seem to be unchanged. Compared with the case of Ma = 6, the maximum density inside the cavity is increased by about 5.5 times for the case of Ma = 30, and it is about 7.3 times for the maximum temperature inside the cavity. However, raising the freestream Mach number seems to not alter the streamline patterns inside the cavity. The three-dimensional effect reduces the maximum density inside the cavity by about 14.5 % to 17.4 % and results in a smaller main vortex compared with the two-dimensional (2D) cavity, and moreover, the slender cavity can weaken the three-dimensional effect due to its larger depth-to-width ratio and the relatively short cavity width. Besides, the vortex-transport theory is proposed, which can well explain the change of gas density inside the cavity for all cases considered in this work.

A new arthroscopic repair technique for triangular fibrocartilage complex using an intracapsular suture: an outside-in transfer all-inside repair

BackgroundArthroscopic repair is a promising, minimally invasive surgical technique for patients with Palmer type 1B peripheral triangular fibrocartilage complex (TFCC) tears. Although several arthroscopic techniques are effective for repairing Palmer type 1B TFCC tears, some shortcomings remain. So, we report an arthroscopic repair technique for the treatment of Palmer type 1B Atzei class 1 TFCC tears using an intracapsular suture: an outside-in transfer all-inside repair.MethodsA retrospective analysis of 38 Palmer type 1B TFCC injury patients admitted to our hospital were randomly divided into 2 groups. The group A was sutured from the outside to the inside, with a total of 21 cases; the group B was sutured with the new arthroscopic repair technique, with a total of 17 cases. Observe and compare the VAS scores and modified Mayo wrist function scores of all patients before 3, and 6 months after the operation and evaluate the incidence of thread knots in patients with different treatment methods. The methodology was performed an arthroscopic intracapsular suture using an outside-in transfer, all-inside repair technique, which is a modified method of the outside-in and all-inside technique using the needle of a 10-mL sterile syringe, for Palmer type 1B TFCC tears. A No. 2 polydioxanone suture was threaded through the needle and entered the wrist joint. Next, the needle was withdrawn carefully along the suture to the proximal tear ulnar surface of the TFCC and penetrated the TFCC, exiting the articular cavity surface of the ulnar side of the torn TFCC. Finally, arthroscopic knotting was performed.ResultsThis new treatment was as effective as the previously arthroscopic techniques and had the advantages of no additional incision and decreased risk of operation-related complications. The incidence of thread knots in the group A (28.57%) was significantly higher than that in the group B (0%), and the difference was statistically significant (P = 0.024). There was no significant difference in VAS score and modified Mayo wrist function scores between the two groups (P > 0.05).ConclusionsThe outside-in transfer, the all-inside repair technique is suitable for Palmer type 1B Atzei class 1 TFCC tears. We recommend this technique as a useful alternative to the conventional methods of repairing Palmer type 1B TFCC tears.

Bond-pad damage in ultrasonic wedge bonding

Utilizing SEM/EDX analysis, microscale fracture at the bond-pad is detected when Cu wire is wedge bonded to a Cu or Al substrate. It is found that when a bond is fractured by pulling the wire similar to a pull test, a bulge on the wire and a cavity in the substrate are formed and fracture occurs in the original substrate. Using a 3D optical profiler, it is revealed that for a constant bond force and bond power, cavity's depth, radius, and surface area increase with bond time. These metrics are proposed as new factors for optimizing the wedge bonding process. A suitable combination of bonding parameters should maximize the cavity's surface area (as it pertains to bond's pull force) while minimizing the cavity's depth relative to the substrate's thickness to prevent damage in the substrate. Furthermore, employing Molecular Dynamics simulations, a possible plastic deformation mechanism for bond-pad damage is proposed. The mechanism points to the potential benefits of using a small-grain-sized substrate, a low transducer's vibration amplitude, and a high transducer's frequency for minimizing the cavity's depth.

Growth of Nb films on Cu for superconducting radio frequency cavities by direct current and high power impulse magnetron sputtering: A molecular dynamics and experimental study

The use of superconducting radio frequency (rf) cavities in particle accelerators necessitates that copper (Cu) surfaces are coated by thin niobium (Nb) films, predominantly synthesized by magnetron sputtering. A key feature of the rf cavities is that they exhibit a complex three-dimensional geometry, such that during Nb film growth vapor is not deposited on a flat substrate. The latter, combined with the line-of-sight nature of the deposition flux in conventional magnetron sputtering methods (including direct current magnetron sputtering; DCMS) yields films with porous columnar morphologies on surfaces of the cavities that do not face the magnetron source. High-power impulse magnetron sputtering (HiPIMS) is a variant of sputtering that generates highly-ionized fluxes. Using electrical fields, such fluxes can be deflected to trajectories that are closer to the substrate normal and, thereby, dense and uniform layers can be deposited on all surfaces of the rf cavities. In the present work, we use classical molecular dynamics simulations to model Nb film growth on Cu substrates at conditions consistent with those prevailing during DCMS and HiPIMS. Our computational results are in qualitative agreement with experimental data (also generated in the present study), with respect to film morphology. Based on this agreement and by studying the evolution of the simulated systems, we suggest that the morphology of HiPIMS-grown films (as compared to their DCMS counterparts) is the result of the combined effects of deflection of ionized sputtered particles to trajectories parallel to the substrate normal, bombardment-induced interruption of crystal growth, and ballistic atomic rearrangement along with dynamic thermal annealing caused by energetic film-forming species. Moreover, the predictions of our model with respect to dynamic processes at the film-substrate interface and their effect on local epitaxial growth are discussed.

Modulation instability in a microresonator with graphene saturable absorber, frequency selective feedback and external potential

Modulation Instability is studied in the presence of an external periodic potential in microresonator comprising of a vertical cavity surface emitting laser with saturable absorber and frequency selective feedback. The role of intensity of input field, pump parameter, diffraction coefficient and saturable absorption on the modulation instability has been investigated. Thus, Modulation instability can be tuned by varying the system parameters. This aspect would be beneficial for the purpose of encryption. It is also observed that modulation instability is not explicitly dependent on externally applied potential whereas the effect of potential is shown implicitly by using numerical analysis. The presence of an external potential give the operating range of resonance frequency of the optical cavity instead of one value at the same system parameters. This operating range of resonance frequency is spatially dependent and varies with the system parameters.

Influence of Processing Conditions on the Generation of Surface Defects in a Heat-and-Cool Hybrid Injection Molding Technique for Carbon Fiber-Reinforced Thermoplastic Sheets and Development of a Suitable Mold Heated by Far-Infrared Radiation.

Recently, hybrid injection molding-a type of overmolding technology in which a short carbon fiber-reinforced thermoplastic is injection molded over a compression-molded carbon fiber-reinforced thermoplastic (CFRTP) sheet-has been introduced. A heat-and-cool hybrid injection molding technique has also been introduced for practical use. The technique yields high-quality molded products. This is achieved through the heating of the mold cavity surface to a temperature higher than the melting point of the base polymer impregnated into the carbon fiber fabric. However, few experimental analyses of the molding phenomena in heat-and-cool hybrid injection molding have been reported. In particular, the effect of the processing conditions on the transfer of the mold cavity surface shape to the CFRTP sheet has not been clarified in detail. Therefore, it has been impossible to take extensive measures when defects are generated in molded products. In this study, a mold is designed and fabricated for use with far-infrared radiation heating, a variotherm technology that is suitable for the experimental analysis of the heat-and-cool hybrid injection molding phenomenon. In particular, a mold is designed and fabricated to continuously perform the following three processes using only an injection molding machine: (1) the radiation heating of both the CFRTP sheet and the mold cavity surface using a far-infrared radiation heater, (2) the compression molding of the CFRTP sheet, and (3) the injection molding of the melt. The effects of the heating conditions of the mold and the injection molding process conditions on the appearance characteristics of the molded products are clarified using this mold and a far-infrared radiation heater.

SURG-20. USEFULNESS OF PHOTODYNAMIC THERAPY (PDT) WITH TALAPORFIN SODIUM FOR GLIOBLASTOMA

Abstract BACKGROUND Photodynamic therapy (PDT) with talaporfin sodium uses the toxicity of singlet oxygen generated by a reaction between a photosensitizer in tumor cells and light with a specific wavelength. PDT was introduced in our hospital in April 2017. We retrospectively analyzed the glioblastoma (GBM) patients treated with PDT and compared with the patients who did not receive PDT. MATERIAL AND METHODS From April 2015 to March 2023, total 145 patients with GBM were treated in our hospital. Among them, patients of recurrence, IDH mutant, biopsy and no chemo/radiotherapy were excluded. The patients’ characteristics, adverse event, changes of the MR image, recurrence pattern, outcome of the patients were analyzed. In addition, survival time of the patients between the PDT group and the non-PDT group was compared. RESULTS A total of 80 GBM patients were analyzed. Forty-four patients received PDT. 4 patients had adverse event; cyst formation, venous infarction, brain swelling, and delirium. In most of the patients, linear high signals of 5-7 mm on DWI were detected at the surface of the resected cavity and matched the PDT-irradiated area from 1 day after PDT. All hyperintense signal on DWI disappeared in about 30 days without any neurological deterioration. Sixty-seven patients had recurrence (PDT group; 33 cases, non-PDT group; 34 cases). Recurrence pattern of distant/dissemination were significantly increased in the PDT group compared with the non-PDT group. The PDT group tended to have longer survival in both OS (p = 0.08) and PFS(p = 0.07) than the non-PDT group. In multivariate analysis for OS, age and MGMT promotor methylation were significant prognostic factors, but not PDT. CONCLUSION PDT was safety and useful for GBM. However, the PDT group had significantly more distant/disseminated recurrences than the non-PDT group. We need to analyze more cases to clarify efficacy and recurrence patterns.

Complimentary Staining of Caries Detector Dyes in Primary Teeth with or without the Application of a Dentine Bonding Agent

Background: Caries detector dyes are introduced to aid in identifying infected dentine. Many researchers claim that they are not specific in identifying infected dentine since dyes also stains sound tooth surfaces. The use of a dentine bonding agent could help in avoiding the penetration of caries detector dyes to some extent in less mineralized primary teeth. This study assesses caries detector dyes penetration in primary teeth with or without dentine bonding agent application. Methodology: Ninety primary extracted carious teeth were considered for the study. Teeth were divided in to two groups (45 teeth each group): group I with dye application without dentine bonding agent and group II with dye application after dentine bonding agent; in both groups three different types of dyes were used. All cavity walls and surfaces of samples in group 1 were stained with caries detector dyes for 10 s, subsequently washed with water for another 10 s and finally air-dried. A similar procedure was carried for teeth in group II after the application of a bonding agent on visibly sound tooth surfaces without the use of an etchant. Results: A statistically significant difference between two groups for staining of different tooth surfaces was noted. A Kruskal–Wallis one-way ANOVA revealed a statistically significant difference in stain removal among the different groups either by distilled water or sodium hypochlorite were observed. Conclusion: A dentine bonding agent can help in preventing caries detector dye penetration in noncarious tooth surfaces of deciduous teeth.

Plasmon‐Coupled GaN Microcavity for WGM Lasing and Label‐Free SERS Sensing of Biofluids

AbstractA signal amplification strategy is always required to improve sensing performance, especially for mass‐prepared, miniature and highly sensitive testing equipment. Herein, an on‐chip integrated biosensor combining microcavity lasing and surface enhanced Raman scattering (SERS) for label‐free biochemical analysis is developed. The gallium nitride (GaN) microrings array is fabricated as a whispering gallery mode microlaser based on totally internal wall reflection, and gold nanoparticles (AuNPs) are further assembled on the cavity surface to confine the optical field synergistically. The improvement of lasing capability indicates the strong light‐matter interaction that is conducive to superior response of biomolecules. As a functional example, a GaN/AuNPs substrate is employed in a urine assay, which avoids the shortcomings of requiring specific reactive reagents on different display modules. Ultimately, the chip not only realizes a wide range of pH (3.6–7.8) identification depending on the ultra‐sensitivity feedback of lasing to the refractive index of liquids, but also significantly enhances SERS signals to enable real‐time determination of the biomolecules in human urine. Even the lowest levels of creatinine (0.02%) can be quantitatively detected in less than a minute; thus this work with dual‐mode spectral analyses realizes rapid diagnosis for urinary systems, as well as provides a more accurate reference for the screening of other diseases.

Ultra high reach optical fiber systems based on CW laser and VCSEL laser operation performance signature

Abstract This study presented the possibility of the hybrid cooperation between continuous wave laser (CW) laser and vertical cavity surface emitting laser (VCSEL) laser operation performance signature for upgrading ultra high reach optical fiber systems. The total estimated lighted power spectrum configuration is simulated with wavelength ranges from 1.543 to 1.555 μm. Total estimated lighted power spectrum configuration is studied with spectral time variations. Total estimated lighted power spectrum is indicated and measured after fiber system length. The total electrical modulated signal amplitude spectrum variations are demonstrated with threshold value after receiver side. The total signal/noise modulated spectrum signal configuration is clarified with time after receiver side. Total estimated electronic power spectrum is measured and tested after receiver system. Also, the total estimated electronic power spectrum configuration is demonstrated with spectral frequency ranges from 200 to 800 GHz.

An experimental investigation on the nanofluids in a cavity under natural convection with and without the rotary magnetic field

This experimental study involves the use of two distinct categories of nanofluids, namely ferromagnetic and non-magnetic, within a square cavity that facilitates natural convection. There are five distinct concentrations associated with each nanofluid. Natural convection arises as a consequence of the thermal gradient between the opposing surfaces of the copper cavity, which has a thickness of 18 gauge. The purpose of utilizing the constructed electro-magnet assembly is to investigate the impact of the rotational magnetic field on the process of heat transfer. The manipulation of magnetic strength can be achieved by regulating the magnetic power and direct current (DC) power. The manipulation of the electromagnet’s spin can also be regulated. In the context of a rotational magnetic field, it is seen that the magnetic flux undergoes a transition from a positive value to an almost identical negative value throughout a full rotation. The optimal heat transfer performance is observed at a nanoparticle concentration of 0.1% by volume (φ) for both nanofluids. In the absence of a rotating magnetic field, the ferromagnetic nanofluid exhibited superior performance. When the Rayleigh number (Ra) is one order smaller than the critical Rayleigh number value, the heat transfer performance is often superior with nanofluid compared to demineralized water.

Coupled Eulerian Wall Film–Discrete Phase model for predicting respiratory droplet generation during a coughing event

Infectious respiratory diseases have long been a serious public health issue, with airborne transmission via close person-to-person contact being the main infection route. Coughing episodes are an eruptive source of virus-laden droplets that increase the infection risk of susceptible individuals. In this study, the droplet generation process during a coughing event was reproduced using the Eulerian wall film (EWF) model, and the absorption/expulsion of droplets was tracked using the discrete phase model (DPM). A realistic numerical model that included the oral cavity with teeth features and the respiratory system from the throat to the first bifurcation was developed. A coughing flow profile simulated the flow patterns of a single coughing episode. The EWF and DPM models were coupled to predict the droplet formation, generation, absorption, and exhalation processes. The results showed that a large droplet number concentration was generated at the beginning of the coughing event, with the peak concentration coinciding with the peak cough rate. Analysis of the droplet site of origin showed that large amounts of droplets were generated in the oral cavity and teeth surface, followed by the caudal region of the respiratory system. The size of the expelled droplets was 0.25–24 μm, with the peak concentration at 4–8 μm. This study significantly contributes to the realm on the site of origin and localized number concentration of droplets after a coughing episode. It can facilitate studies on infection risk assessment, droplet dispersion, and droplet generation mechanisms from other sneezing or phonation activities.

Heat transfer analysis and thermo-mechanical property of M-shape metal-rubber at high-temperature

Particular attention is given to the M-shape metal-rubber (MMR), which is a porous material with cushioning characteristics and excellent heat resistance coated in pipelines. The heat transfer characteristics and thermo-mechanical property of MMR has not been clear due to its complicated micro-porous structures and the coupling effect between structure and performance. In this work, the influence of different parameters (emissivity, density and gap distance) on the equivalent thermal conductivity of MMR were considered at the mesoscopic model level. In addition, thermal stress at different temperatures was used as predefined fields for thermal-mechanical coupling to analyze the transformations of performance. The results indicate that surface emissivity and cavity emissivity during heat transfer exhibit an inverse relationship with MMR thermal conductivity. Furthermore, it is observed that natural convection has the most significant impact on thermal conductivity. And, the thermal conductivity is negative correlation with density and gap distances. Under cyclic loading, stress concentration and plastic strain occur in MMR, and residual thermal stress is generated. The secant stiffness exhibits a positive correlation with temperature, while the loss factor demonstrates a negative correlation, primarily due to thermal expansion.

128 Gbit/s Operation of AXEL with Energy Efficiency of 1.5 pJ/bit for Optical Interconnection

We evaluated the energy efficiency per 1-bit transmission of an optical light source on InP substrate to achieve optical interconnection. A semiconductor optical amplifier (SOA) assisted extended reach EADFB laser (AXEL) was utilized as the optical light source to enhance the energy efficiency compared to the conventional electro-absorption modulator integrated with a DFB laser (EML). The AXEL has frequency bandwidth extendibility for operation of over 100 Gbit/s, which is difficult when using a vertical cavity surface emitting laser (VCSEL) without an equalizer. By designing the AXEL for low power consumption, we were able to achieve 64-Gbit/s, 1.0 pJ/bit and 128-Gbit/s, 1.5 pJ/bit operation at 50 ℃ with the transmitter dispersion and eye closure quaternary of 1.1 dB.

Experimental Demonstration of Modulation Format Recognition Using Reservoir Computing Based on VCSEL With Gradient-Like Boosting

We present a simple experimental approach based on a photonic time delay reservoir computing (RC) system for modulation format recognition. Here an optically injected vertical cavity surface emitting laser with single feedback is trained with the cross sequence of instantaneous characteristics of modulation signals. Three widely used modulation formats including on–off keying, binary phase shift keying, and binary frequency shift keying, where the optical signal-to-noise ratio varies from 4 dB to 36 dB are considered. Besides, we propose a post-processing method of using multiple gradient-like boosting operations for the time delay RC system, in which the residual value between the target value and the actual value is regarded as the target value for multiple training. Experimental and numerical results demonstrate that using multiple gradient-like boosting operations for post-processing can efficiently identify all three modulation formats with the highest accuracy of 100% after optimizing the control parameters such as the feedback strength, injection strength, and number of virtual nodes of the time delay RC system. The simple experimental approach with the proposed multiple gradient-like boosting operations offers a resource-efficient alternative approach to modulation format recognition of future communication.

BLAST: A Wafer‐Scale Transfer Process for Heterogeneous Integration of Optics and Electronics

AbstractA general transfer method is presented for the heterogeneous integration of different photonic and electronic materials systems and devices into a single substrate. Called BLAST, for Bond, Lift, Align, and Slide Transfer, the process works at wafer scale and offers precision alignment, high yield, varying topographies, and suitability for subsequent lithographic processing. BLAST's capabilities is demonstrated by integrating both GaAs and GaN µLEDs with silicon photovoltaics to fabricate optical wireless integrated circuits that up‐convert photons from the red to the blue. The study also shows that BLAST can be applied to a variety of other devices and substrates, including CMOS electronics, vertical cavity surface emitting lasers (VCSELs), and 2D materials. BLAST further enables the modularization of optoelectronic microsystems, where optical devices fabricated on one material substrate can be lithographically integrated with electronic devices on a different substrate in a scalable process.

Study of eigen frequency In1-xGaxAsyP1-y 1.55 µm VCSEL with SiO2 /TiO2 dielectric Bragg reflector

In this work, we focused on investigating the eigen frequency and internal standing wave characteristics of a vertical surface cavity emitting laser operating at a wavelength of 1.55 µm. The design of the cavity involved determining the cavity length, selecting the material for the cavity spacer, and carefully placing the quantum wells within the cavity to achieve maximum overlap with the electric field. In our case, the choice of the dielectric Bragg mirror with SiO2/TiO2 layers helps in achieving high reflectivity and low optical losses. The quantum wells are strategically placed within the cavity to ensure maximum overlap with the electric field. This allows for efficient carrier injection and recombination, leading to laser emission. The specific composition of the quantum wells, In0.54Ga0.46As0.99P0.01 / In0.75Ga0.25As0.55P0.45, indicates the proportions of indium (In), gallium (Ga), arsenic (As), and phosphorus (P) in the material. These compositions are chosen to achieve the desired electronic band structure and emission wavelength. By studying the eigen frequency and internal standing waves in our designed laser cavity, our aim is to understand the resonant modes and behavior of light within the device. This knowledge is crucial for optimizing the laser's performance and improving its efficiency for various applications.

Flow and temporal effects on the sonolytic defluorination of perfluorooctane sulfonic acid

The removal of per- and polyfluoroalkyl substance (PFAS) pollution from the environment is a globally pressing issue, due to some PFAS’ recalcitrant, bioaccumulative, and carcinogenic nature. Destruction via ultrasonic waves (sonolysis) is a promising contender for industrialisation due to; moderate power consumption, applicability to several PFAS and sample types, and limited by-products. Liquid flow rate through an ultrasonic reactor can affect the size, shape, and spatial distribution of ultrasonic cavities and hence their chemical activity. Such effects have not been studied during PFAS sonolysis, and temporal effects have not been studied much beyond the reactant concentration. Here, the effects of varying recirculating flow rate on the ultrasonic defluorination of perfluorooctane sulfonic acid (PFOS) and implications for industrial scale up are presented. Under the ultrasonic power (200 W L−1, 2.27 W cm−2) and frequency (410 kHz) used, flow rates of 79 and 214 ml min−1 enhanced defluorination up to 14 % during 30 min of treatment. However, these effects were temporal and most significant in the initial minutes of treatment. This indicated a dynamic bubble size distribution which stabilised after around 15 min. Defluorination rates of PFOS were compared with measured potassium iodide dosimetry, calorimetry, sonoluminescence (SL), and sonochemiluminescence (SCL). Flow rates which enhanced defluorination correlated moderately with enhanced SCL and negatively impacted SL, calorimetry, and dosimetry. Effects were attributed to perturbed cavity surfaces, leading to asymmetric cavity collapse, and the possibility of enhanced solvated electron production/interaction. SL, SCL, dosimetry, and calorimetric measurements were also temporal, and each showed different times to equilibrate. Flow rates of 439 and 889 ml min−1 returned all sonochemical measurements to the levels without flow, likely due to continued collapse temperature quenching by furthered bubble asymmetry. Flow also enhanced reactor cooling, which is significant for industrial temperature control. The pump energy consumed was small (≈1.9 %) compared to that of the amplifier and chiller, hence, PFOS defluorination was more cost-effective using flow. However, the effect may be limited for the longer treatment times needed for environmental remediation.

A laboratory pilot study on voids in flowable bulk-fill composite restorations in bovine Class-II and endodontic access cavities after sonic vibration

This pilot study investigated whether sonic-powered application of a bulk-fill resin-based composite (RBC) in Class-II or endodontic access cavities reduces void formation. The crowns and roots of 60 bovine teeth with Class-II cavities (C) and endodontic access cavities (E) respectively, were assigned to ten groups (C1–C5, E1–E5). Cavities were filled with RBC (SDR flow + , one increment) using different application techniques: no adaptation (C1 + E1), spreading of RBC on the cavity surfaces with a dental explorer tip (C2 + E2), low (C3 + E3) or high frequency (C4 + E4) direct activation by inserting a sonic-powered tip into RBC and high frequency indirect activation with an ultrasonic insertion tip (C5 + E5). The restorations were light-cured and investigated for voids using microtomography. The number of voids and percentage of voids related to the volume were statistically analysed (α < 0.05). While most voids in Class-II restorations were observed in C4 (p ≤ 0.0031), no significant differences were found between the other groups (p > 0.05). The percentage of voids showed no differences in E1-E5 (p > 0.05). C4 showed a significantly higher percentage of voids compared to C2 (p < 0.001). There is no benefit in applying sonic vibration when filling Class-II or endodontic access cavities.

Evaluation of Freshness of Farmed Two-Year-Old Acipenser persicus during Storage in Ice

Chilled fish is considered a fresh product and helps to ensure the development of world trade. So, the present study aimed to investigate the freshness of two-year-old farmed A. persicus by chemical, microbial, sensory, and physical experiments, and determine its shelf life during ice storage. 20 fish samples were maintained in chilled seawater tanks for 12 days. The ratio of ice powder to fish is of 2 : 1. The fish were separated by layers of ice with a thickness of about 5 cm. The temperature was maintained throughout the storage period at 0-1°C. The fish had an average weight and length of 3.50 kg and 70 cm, respectively. Total bacterial counts, Staphylococcus, and Enterobacteriaceae were acceptable (6.78, 2.96, and 3.99 log CFU·g−1, respectively) for 10 days. Coliform, Escherichia coli, Pseudomonas aeruginosa, Vibrio parahaemolyticus, and Aeromonas hydrophila were not detected during storage. pH (6.89), peroxide value (4.32 meq O2 kg oil−1), thiobarbituric acid (0.96 mg·kg−1), free fatty acids (10.86 g 100 g−1), and total volatile nitrogen bases (19.83 mg 100 g−1) were normal during 10 days. Texture (2.56), odor (2.50), the appearance of gills (2.59), eyes (2.67), belly cavity (2.58), skin (2.49), and outer surface (2.90) of A. persicus displayed a decrease throughout storage ( p &lt; 0.05 ). Sensory characteristics were acceptable for 10 days. Ash was 1.88–2.13% during storage ( p &gt; 0.05 ). Unlike moisture (79.05–81.06%), fat and protein showed a decrease of 1.16−2.33 and 15.65–16.74%, respectively, during storage ( p &lt; 0.05 ). According to the results of the present study, to maintain the economic value of sturgeon and for the expansion of their business, and to preserve the freshness of sturgeon during handling and the effect of freshness on the consumer’s opinion, it is recommended that fisheries use ice for sturgeon transport for 10 days.