Smooth Side Research Articles

Enhanced Acoustic Mixing in Silicon-Based Chips with Sharp-Edged Micro-Structures

The small dimensions of microfluidic channels allow for fast diffusive or passive mixing, which is beneficial for time-sensitive applications such as chemical reactions, biological assays, and the transport of to-be-detected species to sensors. In microfluidics, the need for fast mixing within milliseconds arises primarily because these devices are often used in fields where rapid and efficient mixing significantly impacts the performance and outcome of the processes. Active mixing with acoustics in microfluidic devices involves using acoustic waves to enhance the mixing of fluids within microchannels. Using sharp corners and wall patterns in acoustofluidic devices significantly enhances the mixing by acoustic streaming around these features. The streaming patterns around the sharp edges are particularly effective for the mixing because they can produce strong lateral flows that rapidly homogenize liquids. This work presents extensive characterizations of the effect of sharp-edged structures on acoustic mixing in bulk acoustic wave (BAW) mode in a silicon microdevice. The effect of side wall patterns in different angles and shapes, their positions, the type of piezoelectric transducer, and its amplitude and frequency have been studied. Following the patterning of the channel walls, a mixing time of 25 times faster was reached, compared to channels with smooth side walls exhibiting conventional BAW behavior. The average locally determined acoustic streaming velocity inside the channel becomes 14 times faster if sharp corners of 10° are added to the wall.

Investigation of metal non-opaque foreign bodies of firearm origin by radiation methods

Background. The purpose is to investigate metal non-opaque foreign bodies of firearm origin. Materials and methods. Five cases of removing soft tissue foreign bodies of gunshot origin were investigated, when radiography of the limb soft tissues didn’t detect foreign bodies, but they were removed during the primary surgical wound debridement. X-ray of soft tissue gunshot wounds found no foreign bodies. To study radiographic density, foreign bodies were placed in a foam model with subsequent multislice computed tomography. For spectral analysis of metal foreign bodies, we used wavelengths unconventional for X-ray, which allowed to conduct X-ray fluorescence and X-ray structural studies. Results. Radiographic density of metal foreign bodies ranged from 989 to 2123 HU. Given the different thickness of foreign bodies, from 0.4 to 3.2 mm, the average was 1700 ± 189 HU. The foam had radiographic density of –969 HU with model dimensions of 200 × 100 × 50 mm. When examining samples of foreign bodies, it was found that they are deformed, have different thicknesses. One of the samples is light and smooth on one side, and dark and rough on the other. X-ray fluorescence results: composition on the light side (% by mass): Al — base, Mn — 0.8, Fe — 0.3, Zn — 0.1, Cr — 0.05, Ti — 0.2, corresponding to Al-Mn alloy. The dark side is an oxidized Al-Mn alloy. In the spectrum of the dark side of the sample, the Br-Kα line was detected, which indicates the participation of bromine compounds in the oxidation process. From the smooth side of the sample, the spectrum of this line is not determined. Conclusions. Non-opaque metal foreign bodies of gunshot origin are a rare phenomenon. Metal foreign bodies with low radiographic density are non-ferromagnetic, the use of modern magnetic surgical instruments will not be effective. Visualization of metal foreign bodies, which are not determined by radiography, is possible with the help of multislice computed tomography. The use of the wavelength of primary radiation, which is unconventional for X-ray spectral analysis, and original X-ray optical schemes allows for quantitative determination of the composition and structure of any metal foreign bodies.

Research on the defect depth detection for pipeline steel with double defects using metal magnetic memory method

Metal magnetic memory testing is an effective method to detect the stress state of ferromagnetic materials, and shows great application potential in the field of defect detection of oil and gas pipelines recently. In this paper, the correlation between the normal component of residual magnetic field (RMF) and the defect depth, as well as the applied loading were investigated by tensile tests. The X70 pipeline steels were processed into specimens with double defects of six types of depths and three types of spacings. Some magnetic parameters are defined to characterize the distortion of the RMF in the defect area. The effect of defect depth and applied loading on the magnetic parameters is discussed. The RMF signals measured on the smooth side of the specimens were compared with those on the defective side. Results show that the normal parameters, obtained from the front and back of the specimens, are capable of detecting the defect depth. The slope of the linear relationship between the two increases with the increase of defect spacing. The expressions of normal magnetic parameters were derived based on the Jiles model and magnetic dipole model. The simulation results of defective side and smooth side were compared, as well as the simulation results of different defect spacing. The experimental and numerical simulation results show that the defect depth of pipeline steel can be evaluated by the characteristic parameters of the normal RMF signal under a certain stress level.

High Q-factor Polymer Microring Resonators Realized by Versatile Damascene Soft Nanoimprinting Lithography.

High-quality-factor microring resonators are highly desirable in many applications. Fabricating a microring resonator typically requires delicate instruments to ensure a smooth side wall of waveguides and 100-nm critical feature size in the coupling region. In this work, we demonstrate a new method "damascene soft nanoimprinting lithography" that can create high-fidelity waveguide by simply backfill an imprinted cladding template with a high refractive index polymer core. This method can easily realize high Q-factor polymer microring resonators (e.g., ~5 x 105 around 770 nm wavelength) without the use of any expensive instruments and can be conducted in a normal lab environment. The high Q-factors can be attributed to the residual layer-free feature and controllable meniscus cross-section profile of the filled polymer core. Furthermore, the new method is compatible with different polymers, yields low fabrication defects, enables new functionalities, and allows flexible substrate. These benefits can broaden the applicability of the fabricated microring resonator.

Analysis of Wave Characteristic in Fuel Terminal Serui

The Serui Fuel Terminal is a vital state-owned facility distributing fuel oil throughout Yapen Island, Papua Province. However, this facility has a problem: waves or overtopping, which can even cause damage to existing facilities. This research aims to determine the hydrodynamic process and wave characteristics through theoretical analysis and numerical modeling using Mike21 with Hydrodynamic (HD) and Spectral Wave (SW) Modules. Bathymetry, current and tidal data collected in the field and wave data collected from ECMWF, calibration is carried out by comparing modeling output (currents & tides) with the results of observations and wave propagation and transformation study theoretically and compared with the results of wave modeling, so the accuracy of the modeling results can be reviewed. The validation results of tidal modeling with a MAPE (Mean Absolute Percentage Error) value of 0.3%, current modeling with a MAPE value of 30%, and waves from each orthogonal with an average MAPE of 15%. Generally, wave height on the shoreline is 0.3-0.4 m (calm waves), and the cause of the overtopping that occurs is due to the geometry and type of existing coastal buildings with smooth sloping sides and impermeable, which makes the wave height double with a run-up height 0.6-0.8 m

The first USA continental record of coffee leaf rust (Hemileia vastatrix) on coffee (Coffea arabica) in southwest Florida, USA.

Coffee leaf rust (CLR), caused by Hemileia vastatrix Berk. & Broome (Zaghouaniaceae) is considered the most significant fungal disease of Coffea arabica L. (Rubiaceae), from which berries are harvested and processed to obtain coffee beverage (Talhinhas et al. 2017). In Florida, coffee plants are mainly used as ornamentals due to their fragrant flowers; however, there are ongoing field trials evaluating the adaptability of plants for coffee production to climate conditions in the state (Crane et al. 2005). In November 2021, young seedlings of C. arabica var. caturra from a residence in Naples (Collier County) in southwest Florida were discovered with signs of rust fungus. Minute, yellow, suprastomatal sori 53-81 µm in diam were formed on the abaxial leaf surface, forming blotches. Light-yellow urediniospores measured 29-31 × 20-29 µm, with a reniform or "hunchbacked" shape, had thick walls measuring 1.5-2.5 µm in height, and were dorsally echinulate, the individual spikes measuring 2.5-3.3 µm in height. Spikes were scattered over most of the dorsal surface and form a dense ridge separating the dorsal from the smooth ventral side. (e-Xtra Fig. 1). Symptoms and signs are consistent with published descriptions of CLR produced by H. vastatrix (Ritschel 2005). To confirm the identification, DNA sequencing of the large subunit (LSU) of the ribosomal repeat was done following the protocols of Aime (2006) (GenBank accession number OR296753-OR296754). The Florida specimen shares 100% sequence identity (887/728 bp) with other accessions of H. vastatrix in congruence with maximum likelihood phylogenetic analysis performed in RAxMLv8.0.0 (Stamatakis 2014) (e-Xtra Fig. 2). In addition to CLR, Hemileia coffeicola Maubl. & Roger, causal agent of powdery rust of coffee, produces similar leaf spots on coffee but has a restricted geographical distribution. This agent is found only above 500 m a.s.l. in central Africa (Silva et al. 2006) and produces larger urediniospores (34-40 × 20-28 µm) (Maublanc & Roger 1934) in sori are scattered in abaxial leaf surface giving a powdery appearance. Hemileia vastatrix has been reported from almost every major coffee growing country of the world as well as Hawaii and Puerto Rico (Keith et al. 2022, Ramirez-Camejo et al., 2022). This is the first report of CLR in the continental USA, however, CLR poses a limited threat to the USA agriculture in view of the fact coffee is not commercially grown within the continental USA. A voucher was made of dried symptomatic leaves and deposited at Plant Industry Gainesville Herbarium (PIHG 15712, 16332) and the Arthur Fungarium at Purdue University (PUR N23473). The remaining infested coffee seedlings were destroyed after phytopathological diagnosis, and the pathogen has been absent from all additional screenings since November 2021.

Effect of d-type rib roughness on the turbulent structure of side wall boundary layer for wave-current combined flow

An experimental study has been carried out in a laboratory flume to characterize the turbulence structure and turbulence anisotropy in the boundary layer over smooth and rough side walls for both current alone and wave-current combined flow situations. The rough side wall of the flume comprises a train of circular ribs (diameter, k) attached vertically maintaining uniform spacing p along the streamwise direction. The experiments are performed for smooth surface and rough (ribbed) surfaces with p/k = 2, 3, and 4 to reproduce different cases of d-type rib roughness. The effect of wave-current interaction has been investigated by superposing waves of two different frequencies. Time series data of three velocity components are obtained using Acoustic Doppler Velocimeter. At the near wall region, roughness with higher p/k value enhances the level of turbulent intensity and Reynolds stress significantly. In a channel with smooth side wall, the wave-current combined flow produces lesser turbulence intensity than the current alone flow near the wall. However, for a ribbed wall case, the effect is completely opposite that is, wave-current interacting flow induces higher intensities compared to the reference current alone flow. Substantial decline in the turbulent length scales at the near wall region are observed for ribbed walls, which reveals the strong effect of roughness elements on the turbulent structure. Superposition of wave reduces the length scales even more for both smooth and rough wall cases. As the spacing between two ribs ( p/ k ratio) increases, the energy dissipation rate increases. The analysis of anisotropy invariant map demonstrates a reduction of anisotropy in the vicinity of ribbed wall compared to that for a smooth wall. For wave-current combined flow, the anisotropy invariant data of Reynolds stress tensor varies dramatically within the boundary of map, reflecting significant changes in the state of turbulence.

NEW TECHNOLOGY FOR FEEDING BLACKSMITH INGOTS

Purpose. To make a comparative calculation of the geometric parameters of overfills for blacksmith ingots according to traditional and experimental technology using modern heat-insulating products – domestically produced cross-bars, one of the components of which is paper.
 Research methods. Proven engineering methods of calculations of overflows for ingots and castings, based on the experience of domestic and foreign foundries, as well as our own practical experience and scientific research.
 Results. The calculations of the size of overburden (head) for nine ingots (weigh from 1 to 15 tons) conventionally divided into three groups by design and execution. All parts – the pourer, the through tray and the overflow attachment are made separately, for the ingots of the first group. Assembled, these elements form a casting mold, which is installed on a pallet (2- or 4- place) and filled with a siphon through the central one. According to the current technology, the castings of the first group were lined with the usual molding mixture with liquid glass, sealing in the space between the model and the case of the casting attachment, followed by thermal drying. For drains of the second and third groups, the spouts are also through, pouring – with a siphon on a pallet. The overflow attachment is also removable, it was lined with fireclay bricks and then dried. Structurally, all ingots represented a pressed cone with an upward expansion and a wavy side surface, the bottom part of the ingot represented a pressed cone with an upward expansion and a smooth side surface, the overflow – a pressed cone with an upward narrowing and a smooth side surface.
 Scientific novelty. The vast majority of cases, using cross-bars, the estimated efficiency coefficient of the overfill is 0.28, which made it possible to significantly reduce the size of the overfill and obtain a significant saving of liquid metal for each casting or ingot, was established. For conventional technologies traditionally used in the practice of making blacksmith ingots, the coefficient of effectiveness is 0.19 (for a combined form: the sand part of the form for the overfill and the metal part for the working part of the ingot) and 0.11...0.14 – for a completely sand form.
 Practical value. A method of calculating overfills under the lining with their modern heat-insulating products – cross-bars – has been developed. Due to the favorable thermophysical properties of the material of the cross-bars, it is possible to reduce the size of overflows and, thereafter, reduce the consumption of liquid metal. The use of cross-bars instead of the above-mentioned technologies also significantly improves sanitary and hygienic conditions and a productivity at the site of the preparation of overfills for pouring. New power supply technologies and constructions of overflow extensions for the cross-bars, which have been in operation for about 6 years (the first group) and 3 years (the second and third groups), have been developed.

Solutions with exponential singularity for (3 + 1)-D Protter problems

In the 1950s, Protter proposed multi-dimensional analogues of the classical Guderley–Morawetz problem for mixed-type hyperbolic-elliptic equations on the plane that models transonic flows in fluid dynamics. The multi-dimensional variants turn out to be different from the two-dimensional case and the situation there is still not clear. Here, we study Protter problems in the hyperbolic part of the domain. Unlike the planar analogues, the four-dimensional variant is not well-posed for classical solutions. The problem is not Fredholm — there is an infinite number of necessary conditions for classical solvability. Alternatively, the notion of a generalized solution that may have singularities was introduced. It is known that for smooth right-hand sides, the uniquely determined generalized solution may have a power-type growth at one boundary point. The singularity is isolated at the vertex of the boundary characteristic light cone and does not propagate along the cone. Here, we construct a new singular solution with an exponential growth at the point where the singularity appears.

Diffusion Approximations of Markovian Solutions to Discontinuous ODEs

In a companion paper, the authors have characterized all deterministic semigroups, and all Markov semigroups, whose trajectories are Carathéodory solutions to a given ODE $$\dot{x} = f(x)$$ , where f is a possibly discontinuous, regulated function. The present paper establishes two approximation results. Namely, every deterministic semigroup can be obtained as the pointwise limit of the flows generated by a sequence of ODEs $$\dot{x}=f_n(x)$$ with smooth right hand sides. Moreover, every Markov semigroup can be obtained as limit of a sequence of diffusion processes with smooth drifts and with diffusion coefficients approaching zero.

On the Converse Safety Problem for Differential Inclusions: Solutions, Regularity, and Time-Varying Barrier Functions

This article presents converse theorems for safety in terms of barrier functions for unconstrained continuous-time systems modeled as differential inclusions. Via a counterexample, we show the lack of existence of autonomous and continuous barrier functions certifying safety for a nonlinear system that is not only safe but also has a smooth right-hand side. Guided by converse Lyapunov theorems for (nonasymptotic) stability, time-varying barrier functions and appropriate infinitesimal conditions are shown to be both necessary as well as sufficient under mild regularity conditions on the right-hand side of the system. More precisely, we propose a general construction of a time-varying barrier function in terms of a marginal function involving the finite-horizon reachable set. Using techniques from set-valued and nonsmooth analysis, we show that such a function guarantees safety when the system is safe. Furthermore, we show that the proposed barrier function construction inherits the regularity properties of the proposed reachable set. In addition, when the system is safe and smooth, we build upon the constructed barrier function to show the existence of a smooth barrier function guaranteeing safety. Comparisons and relationships to results in the literature are also presented.

Systematic evaluation of three porcine-derived collagen membranes for guided bone regeneration.

Guided bone regeneration is one of the most common surgical treatment modalities performed when an additional alveolar bone is required to stabilize dental implants in partially and fully edentulous patients. The addition of a barrier membrane prevents non-osteogenic tissue invasion into the bone cavity, which is key to the success of guided bone regeneration. Barrier membranes can be broadly classified as non-resorbable or resorbable. In contrast to non-resorbable membranes, resorbable barrier membranes do not require a second surgical procedure for membrane removal. Commercially available resorbable barrier membranes are either synthetically manufactured or derived from xenogeneic collagen. Although collagen barrier membranes have become increasingly popular amongst clinicians, largely due to their superior handling qualities compared to other commercially available barrier membranes, there have been no studies to date that have compared commercially available porcine-derived collagen membranes with respect to surface topography, collagen fibril structure, physical barrier property, and immunogenic composition. This study evaluated three commercially available non-crosslinked porcine-derived collagen membranes (Striate+TM, Bio-Gide® and CreosTM Xenoprotect). Scanning electron microscopy revealed similar collagen fibril distribution on both the rough and smooth sides of the membranes as well as the similar diameters of collagen fibrils. However, D-periodicity of the fibrillar collagen is significantly different among the membranes, with Striate+TM membrane having the closest D-periodicity to native collagen I. This suggests that there is less deformation of collagen during manufacturing process. All collagen membranes showed superior barrier property evidenced by blocking 0.2-16.4 μm beads passing through the membranes. To examine the immunogenic agents in these membranes, we examined the membranes for the presence of DNA and alpha-gal by immunohistochemistry. No alpha-gal or DNA was detected in any membranes. However, using a more sensitive detection method (real-time polymerase chain reaction), a relatively strong DNA signal was detected in Bio-Gide® membrane, but not Striate+TM and CreosTM Xenoprotect membranes. Our study concluded that these membranes are similar but not identical, probably due to the different ages and sources of porcine tissues, as well as different manufacturing processes. We recommend further studies to understand the clinical implications of these findings.

Vaginal reconstruction with a double-sided biomembrane-a preclinical experimental study on large animals.

Tissue engineering techniques bring the promise of vaginal reconstruction with low invasiveness and fewer complications. However, existing biomaterial scaffolds remain limited in efficient vaginal recovery, focusing only on regenerating an epithelial layer, but muscle layers are missing or abnormal. The lack of a multi-tissue hierarchical structure in the reconstructed vagina leads to shrinking, stenosis, and fibrosis. Here, an acellular matrix named a double-sided biomembrane (DBM) is demonstrated for vaginal recovery. The regeneration of epithelial and muscle layers is achieved simultaneously since the smooth side of the DBM is helpful for guiding epithelial cell growth, while its loose and porous side guides muscle cell growth. In addition, the DBM demonstrates excellent mechanical properties similar to vaginal tissue, and hydrophilicity. Therefore, neovaginas were observed in the fourth and twelfth weeks after DBMs were transplanted to repair full-thickness vaginal defects (4 cm) that we established in large animals. The DBMs can effectively promote rapid epithelialization, the formation of large muscle bundles, higher rates of angiogenesis, and the restoration of physiological function in a neovagina. That is, the injured vagina achieves nearly complete recovery in anatomy and function, similar to a normal vagina. These preclinical results indicate that the DBM has prospects for vaginal injury repair.

Experimental and Numerical Study of Open Channel Flow with T-Section Artificial Bed Roughness

Experimental and numerical studies have been conducted on the effects of bed roughness elements such as cubic and T-section elements that are regularly half-channel arrayed on one side of the river on turbulent flow characteristics and bed erosion downstream of the roughness elements. The experimental study has been done for two types of bed roughness elements (cubic and T-section shape) to study the effect of these elements on the velocity profile downstream the elements with respect to different water flow discharges and water depths. A comparison between the cubic and T-section artificial bed roughness showed that the velocity profile downstream the T-section increased in smooth side from the river and decrease in the rough side from it compared with the case when a cubic artificial bed roughness is used. By comparing the results for the element shapes, it can be notices that the T-section bed roughness element more effective compared to cubic shape for both sides of the channel. The numerical method has been done using Computational Fluid Dynamic (CFD) method. A validation for the CFD model with the experimental study have been carried out for a specific flow discharge and water depth. The results indicated that the velocity distribution profiles downstream the bed roughness elements in both sides shown very good agreement for manning coefficients between the numerical and experimental studies. The range of errors between the experimental and numerical study have been calculated using Root Mean Square Error (RMSE) approach, which is found that the RMSE is approximately equal to 1 in case of cubic bed roughness and the RMSE is about 1.5 in case of T-section bed roughness for both smooth and rough sides. Furthermore, the influence of the velocity profile and the bed erosion downstream of the T-section element under the effect of tides have been investigated using the CFD method, which is commonly happened in Shat al-Arab south of Iraq. The results show that the tide of the flow has a reverse effect on the velocity profiles for both sides. Since the velocity profile downstream of bed roughness region increase in the rough side and decrease in the smooth side compared with the normal flow of the river.

An individual ZnO microwire homojunction LED with ultraviolet electroluminescence spectrally purified using Pt nanoparticles cladding

Low-dimensional ultraviolet light sources are enormous significance due to their wide range of potential applications, ranging from bioscience and high-resolution biological imaging, environmental conservation to public hygiene. Nevertheless, developing energy-efficient and cost-efficient light sources still remains serious challenges. In this study, p-type ZnO microwires with Sb-incorporation (ZnO:Sb MWs) were synthesized individually. The p-type conductivity was proofed using an individual MW based back-gated field-effect transistor; while the ZnO:Sb MWs with quadrilateral cross-section exhibited stimulated emission resonant in well-defined Fabry-Perot mode on the benefit of single-crystalline quality and atomically smooth side facets. The newly synthesized ZnO:Sb MW was further used to fabricate homojunction light-emitting device by employing n-type ZnO film as electron-transporting layer. A strong ultraviolet emissions peaking at around 378.5 nm was achieved upon forward biased electrically, but illustrating much broader electroluminescence (EL) linewidth. Introducing Pt nanoparticles (PtNPs) with desired plasmons, the light-out intensity is significantly enhanced. Particularly, the broad EL profiles narrowed to about 16.6 nm at high injection regime, achieving electron-holes radiative recombination in the ZnO:Sb MWs active region. The results exhibit a prominent progress achieving high-quality ZnO nano/microstructures with genuine p-type conductivity, which has great hopes for its future applications and development in ZnO homojunction optoelectronic devices.

Antibacterial and osteoconductive polycaprolactone/polylactic acid/nano-hydroxyapatite/Cu@ZIF-8 GBR membrane with asymmetric porous structure

Repair of periodontal and maxillofacial bone defects is a major challenge in clinical. Guided bone regeneration (GBR) is considered one of the most effective methods. However, the efficacy of currently available GBR membranes for repair is frequently limited by their poor osteogenic potential and lack of antibacterial activity. The first step in this investigation was to construct a zinc-based zeolite-imidazolate framework loaded with copper ions (Cu@ZIF-8). Following that, a novel polycaprolactone/polylactic acid/nano-hydroxyapatite/Cu@ZIF-8 (PCL/PLA/n-HA/Cu@ZIF-8) GBR membrane was developed using a simple porogen with nonsolvent-induced phase separation (NIPS) approach. The produced membrane with asymmetric porous structure (one smooth side and one rough side) possesses hydrophilicity corresponding to the roughness of its two sides. The superior mechanical property, stability of degradation, and ion release capability of the membrane all contribute to the clinical feasibility. Additionally, in vitro biological experiments demonstrated that the PCL/PLA/n-HA/Cu@ZIF-8 membrane had favorable osteogenic and antibacterial properties, which suggests the high potential for application in the GBR procedure.

Cefazolin Loaded Oxidized Regenerated Cellulose/Polycaprolactone Bilayered Composite for Use as Potential Antibacterial Dural Substitute.

Oxidized regenerated cellulose/polycaprolactone bilayered composite (ORC/PCL bilayered composite) was investigated for use as an antibacterial dural substitute. Cefazolin at the concentrations of 25, 50, 75 and 100 mg/mL was loaded in the ORC/PCL bilayered composite. Microstructure, density, thickness, tensile properties, cefazolin loading content, cefazolin releasing profile and antibacterial activity against S. aureus were measured. It was seen that the change in concentration of cefazolin loading affected the microstructure of the composite on the rough side, but not on the dense or smooth side. Cefazolin loaded ORC/PCL bilayered composite showed greater densities, but lower thickness, compared to those of drug unloaded composite. Tensile modulus was found to be greater and increased with increasing cefazolin loading, but tensile strength and strain at break were lower compared to the drug unloaded composite. In vitro cefazolin release in artificial cerebrospinal fluid (aCSF) consisted of initial burst release on day 1, followed by a constant small release of cefazolin. The antibacterial activity was observed to last for up to 4 days depending on the cefazolin loading. All these results suggested that ORC/PCL bilayered composite could be modified to serve as an antibiotic carrier for potential use as an antibacterial synthetic dura mater.

CHARACTERIZATION OF POLITANICAL BACTERIA IN BELLED MEATBALLS FOR SALE IN GORONTALO CITY

This study aims to characterize the contaminating bacteria in grilled meatballs that are sold in Gorontalo City.
 The method in this study uses a qualitative approach that is descriptive. The type of data used is primary data. Primary data in this study are laboratory results and questionnaire results and secondary data in this study are data obtained from various literature, related journals.
 The results of the characteristic study on macroscopic examination showed that the different characteristics of each isolate could be observed. Colony shape, margin, elevation, and color are among the characteristics revealed by macroscopic observation of the isolate code. Colonies are irregular and round. Smooth colony side. There are only three variations of colony elevation, namely milky white and yellowish white: curved, uphill, and flat. Based on the microscopic results, isolates P3, P4, and P5 showed a purple stem (bacilli) cell shape, indicating that this form was a Gram-positive bacterium. Isolates P1, P2, and P6 showed rod (bacillus) cell shape and were Gram-negative. For the biochemical test of simon citrate, 3 isolates were negative for citrate and 3 isolates were positive for citrate.

Experimental investigation of shear fatigue behavior of composite stiffened panels with impact damage

Shear fatigue experiments were performed to investigate the fatigue behavior and failure mechanism of composite stiffened panels. Low-velocity impact was conducted on the stiffener flange from the smooth side. Barely visible impact damage was introduced and it decreased the buckling and failure loads of the stiffened panels by 13.5% and 14.4%, respectively. The delamination and residual strength did not exhibit noticeable changes when the fatigue load level was set at 40% of shear strength after impact (SSAI). However, when it was increased to 67% of SSAI, delamination grew steadily and stiffener damage caused the delamination growth rate to temporarily increase by approximately 5-fold. A clear correlation was observed between the delamination growth and sublaminate buckling. Delamination grew over the entire web of the stiffener, resulting in the ultimate failure of the stiffened panels.

Joseph and Lucy Smith's Tunbridge Farm: An Archaeology and Landscape Study

Joseph and Lucy Smith's Tunbridge Farm: An Archaeology and Landscape Study