Wide Rib Research Articles

Transmembrane protein 53 craniotubular dysplasia (OMIM # 619727): The skeletal disease and consequent blindness of this new disorder

Craniotubular dysplasia, Ikegawa type (OMIM #619727) denotes the autosomal recessive skeletal disease identified in 2021 featuring blindness acquired in childhood. Five young members of four Indian families harbored a homozygous indel within TMEM53 (OMIM *619722), the gene that encodes transmembrane protein 53 (TMEM53). When intact, TMEM53 spans the nuclear envelope of osteoprogenitor cells, dampens BMP-SMAD signaling, and thereby slows bone formation. Consequently, defective TMEM53 accelerates osteogenesis. Herein, an American boy is compound heterozygous for a novel deletion and a novel missense mutation within TMEM53. His vision and sensorineural hearing became impaired. Radiographic survey revealed diploic thickening of his skull, broad calvarial and facial bones, skeletal modeling errors, vertebral body flattening, wide ribs, and osteopenia of expanded bones. DXA areal bone density (gm/cm2) Z-scores were low. His optic, auditory, and spinal canals were narrow. Mineral metabolism was intact. Serum alkaline phosphatase and osteocalcin levels were normal yet CTX was high. Iliac crest histomorphometry documented accelerated bone formation. His acute vision loss briefly improved following prednisone administration, optic canal decompression, and optic nerve sheath fenestration, but then progressed despite further surgeries and zoledronate treatment aimed to suppress bone turnover. Next generation sequencing of genes associated with elevated skeletal mass, including from high bone turnover, did not suggest an etiology. Whole genome sequencing then revealed within TMEM53: i) a paternally transmitted 54-base deletion, which included the mRNA splice acceptor site for exon 2 as well as 31 bases of exonic sequence (c. 62-23_92del), and ii) a maternally transmitted missense variant (c.650C > T, p.Ser217Leu: NM_024587.4/NP_078863.2) which is extremely rare in gnomAD (frequency = 0.000036), replaces Ser217 highly conserved across species, and is scored as damaging by SIFT and Mutation Taster. We call this new osteopathy TMEM53 craniotubular dysplasia.

Prenatal phenotype and genetic analysis of a fetus with Fibrochondrogenesis 1 due to compound heterozygous variants of COL11A1 gene

To explore the genetic etiology of a fetus with short limbs identified by prenatal ultrasonography. A fetus detected with short limb malformations at Shengjing Hospital Affiliated to China Medical University on October 25, 2021 was selected as the study subject. Prenatal ultrasound and post-abortion imaging were carried out to determine the phenotypic characteristics of the fetus. Amniotic fluid sample of the fetus and peripheral blood samples of its parents were collected. Following extraction of genomic DNA, whole-exome sequencing was carried out. Candidate variants were verified by Sanger sequencing. Online software was used to predict the structural changes of the mutant proteins. Prenatal ultrasound showed that the fetus had a small bell-shaped thorax, markedly shortened limbs, flat midface, a small nose with anteriorly tilted nostrils, and a small mandible. Post-abortion CT showed typical short and wide fetal ribs, cupped metaphyses at both ends, short long bones with wide metaphyses, resulting in a dumbbell-shaped appearance and curved thoracic vertebrae. Whole-exome sequencing revealed that the fetus had harbored compound heterozygous variants of the COL11A1 gene, namely c.2251G>T and c.3790G>T, both of which were predicted to alter the important Gly-X-Y structure of collagen protein. Sanger sequencing confirmed that the variants were respectively inherited from its parents. A rare fetus with Fibrochondrogenesis type 1 due to compound heterozygous variants of the COL11A1 gene has been diagnosed. Above finding has enabled genetic counseling and reproductive guidance for this family.

Further characterization of ARSK-related mucopolysaccharidosis type 10.

Mucopolysaccharidosis type 10 is caused by biallelic variants in ARSK, which encodes for a lysosomal sulfatase. To date, seven patients with a mild phenotype resembling spondyloepiphyseal dysplasia or multiple epiphyseal dysplasia have been described. In this report, we present two novel ARSK variants and report clinical and radiological findings of three patients. The patients' initial complaints were hip or knee pain and a waddling gait. All patients showed normal intelligence, normal hearing and eye examinations, and none had organomegaly. While typical dysostosis multiplex findings were not observed, mild platyspondyly with anterior beaking of some vertebral bodies, irregular vertebral endplates, wide ribs, inferior tapering of the ilea with a poorly developed acetabulum, irregularity of the central part of the femoral head, delayed ossification of the carpals were noted. Remarkably, all patients showed metaphyseal striation of the long bones, a crucial diagnostic clue to identify ARSK-related MPS type 10. Interestingly, vertebral involvement regressed during follow-up. On the other hand, hip dysplasia progressed in all patients. In conclusion, this study provides valuable long-term results on a recently discovered form of MPS.

Effects of MPL Pore Size Distribution on Components of Oxygen Transport Resistance Increased Due to Water Accumulation in a PEFC

To increase the power output of PEFC, management of generated water is extremely important. A gas diffusion layer (GDL) with a microporous layer (MPL) on the cathode side is thought to play important roles in drainage of product water and optimizing oxygen transport, but the details of the mechanism have not been elucidated. In this study, to reveal the water and oxygen transport phenomena, the components of oxygen transport resistance were evaluated using the limiting current analysis (1) for two types of MPL with different pore size distributions. Further, the water distributions in the cathode side MPL and catalyst layer (CL) were observed by a freezing method and a cryo-SEM (2). The active area of the cell used in this study was 1.8 cm2 (0.9 cm × 2.0 cm). The anode and cathode flow fields were parallel straight type with 1.0 mm wide ribs and channels. The anode side was supplied with hydrogen, and the cathode side was supplied with a mixed gas of oxygen and nitrogen. The gas flow rates were 500 sccm for the anode and 4000 sccm for the cathode. The relative humidity of the supplied gases was 90%. Experiments were conducted under two different cell temperature, 30°C (low temperature condition) and 80°C (high temperature condition). The catalyst coated membrane was produced by Japan Gore (PRIMEA). We used two types of MPL with different pore size distributions for the cathode GDL: MPLs with one peak (conventional type) and with two peaks. The MPLs are called MPL-1 and MPL-2, respectively. For the anode side, a GDL with an MPL (SGL, 28 BC) was used. This study used the limiting current analysis developed by the authors (1). The developed method extended the conventional method to the separation under flooded conditions, considering vapor transport and water distribution. Inside the CL, it was assumed that the water production rate dominates the water accumulation, which is proportional to current density. Outside the CL, it was assumed that the product of total pressure and current density determines the water accumulation (1). The experiments were conducted with different back pressures (110 kPa, 140 kPa, 180 kPa) and different oxygen concentrations (1%, 2%, 4%, 6%, 8%, 12%, 15%, 18%, 21%) for the cathode side. Figure 1 shows the total oxygen transport resistances at 110 kPa. There is a significant difference in the tendencies of the total oxygen transport resistance between the MPL-1 and the MPL-2 under the low temperature condition, while the tendencies are similar under the high temperature condition. This suggests that the effects of water accumulated in the cell are larger at lower temperature. Figure 2 shows the results separating the total oxygen transport resistance into two resistances. The I Lim is the limiting current density. The R P and R NP are the pressure-dependent and -independent oxygen transport resistances. These correspond to the oxygen transport resistances outside and inside the CL. Under the low temperature condition, the pressure-dependent oxygen transport resistances (corresponding to those outside the CL) are different between the MPL-1 and the MPL-2. The pressure-independent resistances (corresponding to those inside the CL) are similar. These mean that the smaller total oxygen transport resistances with the MPL-2 in Figure 1 are caused mainly by the smaller resistance outside the CL. Before the separation, we predicted that the increase in the total oxygen transport resistance is suppressed by the MPL-2 due to enhanced drainage of product water from the CL. However, Figures 2(a) and (c) revealed that the R P of the MPL-2 becomes smaller than that of the MPL-1 rather than the R NP. This may be considered because the larger pores in the MPL-2 form drainage pathway for product water at the low temperature condition, which significantly contributes to increasing the oxygen transport pathway through the smaller pores. As expected from Figure 1, there is no significant difference in the R P and the R NP between two types of the MPL under the high temperature condition (Figures 2(b) and (d)). The water distribution in the vicinity of MPL-2 was observed after discontinuing operation at 2.0 A/cm2 just before the limiting current condition. The experiment was conducted with 30°C, 180 kPa back pressure, and 21% oxygen concentration. Cryo-SEM images showed that there was ice at the MPL/CL interfaces. Additionally, ice crystals were observed at the larger pores in the MPL-2, supporting the above consideration, the drainage pathway for product water through the larger pores.Reference (1) Y. Iizuka, et al., ECS Transactions, 104(8), 83-92 (2021). (2) Y. Aoyama, et al., Electrochem. Commun., 41, 72-75 (2014). Figure 1

Constraining ring rolling of thin-walled conical rings with transverse ribs

As critical load-bearing components of aerospace equipment, thin-walled conical rings with inner transverse ribs (TWCRITR) are widely used for manufacturing rocket body, aircraft fuselage and space station shell et al., due to light weight, high strength and high load-bearing capacity. However, TWCRITR cannot be manufactured by traditional ring rolling (TRR), due to thin skin and high ribs. Aimed at this problem, a novel constraining ring rolling method (CRR) is proposed in this work to achieve the near-net-shape manufacturing of TWCRITR with high performance and efficiency. CRR innovatively uses a constraint roll and two baffles to fully constrain the diameter and height enlargement of ring, which ensures that the CRR process is still stable and the metal is enforced to flow axially to form high and wide ribs. Owing to the extreme geometry of TWCRITR and the complicated constraints of rolls in CRR of TWCRITR, the inherent relation between geometric and process parameters, stress state and metal flow is complicated, and it cannot be quantitatively determined by the FE simulation or experiment. Hence, the mechanical model which can determine the quantitative relation between geometric and process parameters, stress state and metal flow in CRR of TWCRITR is firstly established by using the slab method and upper bound method. Secondly, three new metal flow modes related with rib width in CRR of TWCRITR are found based on the established mechanical model. The first one is that the real-time height difference of two ribs slightly fluctuates and the two ribs almost grow synchronously when the width of two ribs is almost identical. The second one is that the rib with small width at the small end grows much faster than the rib with large width at the large end when the width difference of two ribs exceeds a critical value. The third one is that the rib with small width at the large end grows much faster than the rib with large width at the small end when the width difference of two ribs exceeds a critical value. Further, the quantitative relations between the metal flow resistance, divided-flow plane and rib growth under three metal flow modes are revealed theoretically, and consequently the mechanisms behind three metal flow modes in CRR of TWCRITR are clarified theoretically. Finally, the simulation and experiment for CRR of TWCRITR are conducted, and TWCRITR with 3 mm in skin thickness, 7 mm in rib width and 12.5 mm in rib height (the ratio of rib height to skin thickness is 4.16 and the ratio of rib width to skin thickness is 2.33) are stably rolled. Moreover, the roundness of rolled TWCRITR is good (it nearly approaches the inner surface roundness of constraint roll). The predicted values of rib height using the established mechanical model are in good accordance with the simulated and experimental ones, which validates the established mechanical model. Through analyzing the novel CRR process and complicated metal flow mechanisms, it is demonstrated that CRR is promising for manufacturing TWCRITR with high performance and efficiency.

It's all in the past: how do colonial legacies between host and home countries affect the expatriate experience?

PurposeWithin the expatriation subset of the wider IB literature, the focus of research has been on contemporary contextual factors. The purpose of this paper is to link the present to the past by investigating how the individual expatriate experience may be affected by a colonial legacy between host and home countries.Design/methodology/approachGiven the exploratory nature of this study, a qualitative interview-based approach eliciting thick, detailed descriptions of the practical experiences of seven Japanese expatriate managers working in Malaysia was adopted. These were supplemented by additional interviews with three host-country nationals who work alongside some of the expatriates. The data were analysed through a two-stage coding process.FindingsThe expatriate respondents were largely unanimous in their view that the colonial past between the two countries had no negative impact on their experiences in Malaysia, and the Malaysian interviewees corroborated this. On the contrary, the majority of the expatriates actually spoke positively about their experiences. This was especially true for expatriates in both the tourism and education/research field whose work was linked in some way to the period of Japanese occupation.Research limitations/implicationsThe small, single-context nature of the investigation limits generalisation. There are also many particularities in this study (the nature of Japanese-Malaysian postcolonial relations, cultural values of the Malaysians and Japanese, and so on) that are perhaps not easily relatable to other contexts. Having said this, qualitative research is not always geared towards generalisability but rather towards contextual intricacies and nuances.Originality/valueWhile most of the extant literature on expatriation has examined largely contemporary factors, this paper explores the impact of more historical events on the expatriate experience. Although such events may seem distant from an expatriate's current activities, this study suggests that in certain circumstances, they may have a lingering effect.

Effects of Condensed Water on Oxygen Transport Resistance Components Separated By the Limiting Current Analysis in PEFC

To increase the power output of PEFC, management of generated water is extremely important. In previous study, using a heat conduction and water vapor diffusion model, appropriate operating conditions were investigated to reduce oxygen transport resistance (1). However, it clarified only total oxygen transport from catalyst layer (CL) to channel without considering the effect of condensed water. In this study, the oxygen transport resistances in CL and in the other parts were evaluated quantitatively under flooding conditions. The water distribution in the cathode side micro-porous layer (MPL) and CL were observed by using a freezing method and a cryo-SEM (2).In this study, active area of the cell was 1.8 cm2. The anode and cathode flow fields were parallel straight. Two kinds of separators with 0.3 mm or 1.0 mm width rib and channel were employed (we call as 0.3 mm separator and 1.0 mm separator respectively). The anode side was supplied with hydrogen, and the cathode side was supplied with a mixed gas of oxygen and nitrogen. The gas flow rates were 100 sccm for the anode and 2000 sccm for the cathode. All experiments were conducted with 81%RH. We used gas diffusion layer (GDL) with MPL: 28 BC (made by SGL Co., Ltd.). The catalyst coated membrane was produced by Japan Gore-Tex Inc.The oxygen transport resistances were measured by using the limiting current method (3). Until now, decomposition of oxygen transport resistance is limited under dry condition because it is on the assumption that total oxygen transport resistance is constant. Then, this study introduced the separation of oxygen transport corresponding to inside and outside CL under flooding condition. Inside the CL, it was assumed that the water production rate dominates the water accumulation, which is proportional to current densities. Outside the CL, it was assumed that the product of pressure and current density determined the component of oxygen transport resistance. Based on these novel assumption, division of oxygen transport resistance was determined by a least square error calculation of actual total oxygen transport resistances and theoretical values. this experiment was conducted with different pressure (100 kPa, 140 kPa, 180 kPa), and different oxygen concentration (1%, 2%, 4%, 6%, 8%, 12%, 16%, 20%, 24 %). The cell temperature was set at 35°C and 80°C.Figure 1 shows the results of oxygen transport resistance in each inside and outside CL. I Lim is limiting current density. R P and R NP are pressure-dependent or independent oxygen transport resistances, respectively. These are corresponded to the oxygen transport resistance outside and inside the CL. In Figure 2, actual total oxygen transport resistances (R T) are shown as dots, and theoretical values which are obtained from the results of Figure 1 are shown as line. Both results are in good agreement, and the effectiveness of the oxygen transport resistance decomposition was confirmed.From the results at Figure 1, focusing on the temperature condition (1.0 mm separator), R P increases from low current density region at low temperature. But, R NP shows the similar behavior which is suppressed at low current density and increases from high current density region. These results indicate that high temperature is good at water discharge outside CL in case of present GDL.To clarify the reason why R NP increases in high current density region, effect of the difference in rib and channel widths was investigated. In case of 0.3 mm separator, R NP is relatively constant in high current density region. This result suggests that wider rib and channel increase the oxygen transport resistance in the CLFigure 3 shows the water distribution in the vicinity of MPLs at just before limiting current condition. This experiment was conducted with 80°C, and 24% oxygen concentration. No ice is observed in the MPL and CL for 0.3 mm separator (Figure 3 (a)). On the other hand, ice layer was observed at the MPL/CL interface for 1.0 mm separator (Figure 3 (b)). This is related to the result that R NP increases in high current density region in case of 1.0 mm separator (Figure 2). When wider channel separator is employed, the contact of MPL and CL becomes worse. As a result, water is accumulated at the MPL/CL interface and the water prevents oxygen transport to the CL under the channel. These results suggest that a cell structure that improves the MPL/CL interface contact is important to suppress oxygen transport resistance.Reference Kitami, et al., ECS Transactions, 92(8), 213-221 (2019).Y. Aoyama, et al., Electrochem. Commun., 41, 72-75 (2014)David A. Caulk, et al., Electrochem. Soc., 157(8), B1237-B1244 (2010) Figure 1

Tridimensional nonhydrostatic transient rip currents in a wave-resolving model

Flash rips and surf eddies are transient horizontal structures of the order of 10 to 100 m, which can be generated in the surfzone in the absence of bathymetric irregularities. They are traditionally evaluated in a depth averaged setting which involves intrinsic horizontal shear instabilities and the direct generation of vorticity by short-crested waves. In this article, we revisit the processes of surf eddy generation with a new three-dimensional wave resolution model (CROCO) and provide a plausible demonstration of new 3D non-hydrostatic instability and turbulent cascade. We first present a quick overview of a compressible free surface approach suitable for nearshore dynamics. Its ability to simulate the propagation of surface gravity waves and nearshore wave-driven circulation is validated by two laboratory experiments. Next, we present a real world application from Grand Popo Beach, Benin, forced by waves with frequency and directional spreading. The generation of surf eddies by the 3D model differs from depth-averaged models, due to the vertical shear associated with shallow breaking waves. In this case, the generation of eddies from both horizontal shear instability and the breaking of short-crested waves is hampered, the former by stretching the alongshore current and the latter by inhibiting the inverse energy cascade. Instead, the vertical shear flow is subjected to forced wave group variability and Kelvin–Helmholtz type instability at an inflection point. Primary and secondary instabilities generate spanwise and streamwise vorticity connecting small-scale eddies to larger horizontal surfzone structures. Streamwise filaments, appearing as 5 m wide ribs or mini-rips, can extend beyond the surfzone but with moderate energy. These results appear consistent with the velocity spectra and observed patterns of tracers and suspended sediments at Grand Popo Beach. The timescale associated with the mean shear-induced turbulence is several times the wave period and suggests an intermediate range between breaker-induced turbulence and large-scale surf eddies.

Submillimeter features on injected acrylonitrile butadiene styrene parts: Visualization of the flow and numerical simulation

AbstractNumerical simulation of classical dimension parts with micrometric textures on their surface is still difficult to master. The limit condition of the calculations, and in particular, the implemented values, characteristics of the polymer and thermal exchanges (polymer/mold) strongly impact the results. Starting from a model with a 370 μm wide rib, by means of a numerical simulation, a study was done on the evolution of the material flow front velocities and the flow lengths in both the macroscopic part and the microgroove. This innovative visualization mold design was used to determine the velocities from an experimental perspective and to discuss the calculation conditions. On the one hand, there are significant differences regarding the choice of the no flow temperature (~ 40 K) used in the calculation code, the analytical heat transfer equation as well as the experimental results. On the other hand, according to the no flow temperature, it may be necessary to consider, during the filling phase, a perfect mold/polymer thermal contact in the groove. Depending in particular on the injection velocity and the geometry of the micro textures, a characteristic time can be determined which defines an optimal operating point for the topographic texture of the part.

The first postcranial oreodont (mammalia, Artiodactyla, Merycoidodontidae) skeleton from Mexico: Description and paleobiological significance

In this study, the first postcranial skeleton of an oreodont (Merycoidodontidae, Artiodactyla) found in Mexico is described and discussed. This family was very successful, quasi endemic of North America, and lived from the Late Duchesnean North American Land Mammal Age, acronymed NALMA (Late Eocene) to the Late Hemphillian NALMA (early Late Miocene), roughly between 38 Ma to 5.2 Ma. Oreodonts were diverse (~27 genera, 69 species), and fairly abundant. However their record in Mexico is modest: two genera in northeastern Chihuahua (Rancho Gaitán local fauna, Late Duchesnean), one genus in Aguascalientes (Zoyatal local fauna, early Hemingfordian), one genus in northwestern Oaxaca (Yolomécatl local fauna, latest Uintan-earliest Duchesnean) and one genus in central Oaxaca (Suchilquitongo local fauna, latest Arikareean-Early Hemingfordian). Therefore, the finding in Tehuitzingo, southern Puebla of an articulated postcranial skeleton referred to the Merycoidodontidae, described below, is quite important and significant.The fossil material was recovered from the Tehuitzingo Formation, which largely fills the namesake basin; such geologic unit is a thick lacustrine-fluvial, fine-grained, indurated sequence that includes strata of silicified limestone and siltstone/sandstone interbedded by tuff/ignimbrite sheets, one of them yielded a K-A date of 29.9 ± 0.8 Ma (Early Oligocene), confirmed by the 29.96 Ma age of the overlying Puerto El Gato Formation. The fossil locality lies near Atopoltitlán, and yielded a medium-sized mammalian, articulated, postcranial skeleton. The recovery, preparation and study of the material were performed using standard paleontological methods and techniques. The fossil exhibits among others, the following features: Antero-posteriorly wide ribs, astragalus with double trochlea, ecto- and mesocuneiform fused, phalanx II smaller than the others, and hoofed ungual phalanges. Such characters set it in the artiodactyl Family Merycododontidae, making it the first of its kind in Mexico. The size of the postcranial skeleton corresponds to that of the Whitneyan-Late Arikareean Eporeodon; however, the lack of skull and jaws prevents a positive assignment to this or other merycoidodont genus.Finally, the Tehuitzingo species was tropical, probably cursorial, (?herding), and lived in an open country ecologic setting, with ready access to water supply. Unusual taphonomic conditions led to its preservation as an articulated, headless carcass.

Clinical and radiological findings in Brazilian patients with mucolipidosis types II/III.

The present study aims to provide orientation for clinicians and radiologists to recognize the most prevalent findings leading to diagnosis in mucolipidosis from a description of the natural history of five Brazilian cases. We conducted an observational and retrospective study of five patients with clinical and radiological diagnosis of mucolipidosis. Clinical evaluation consisted of information obtained from records and including physical, neurologic, and dysmorphic evaluations. Radiologic studies consisted of complete skeletal radiographs of all patients. Enzyme assessment was performed for confirmation of the diagnosis. The five patients were referred for genetic evaluation due to disproportionate short stature with short trunk accompanied by waddling gait. Age at referral varied from 11months to 28years. The most prevalent findings were joint restriction (4/5 patients), neuropsychomotor developmental delay (3/5), coarse facies (2/5), hypertrophic cardiomyopathy (2/5), and mental retardation (1/4 patients). The most common radiological findings were anterior beaking of the vertebral bodies (5/5), shallow acetabular fossae (5/5), epiphyseal dysplasia (5/5), platyspondyly (4/5), pelvic dysplasia (4/5), decreased bone mineralization (4/5), scoliosis (3/5), wide and oar-shaped ribs (3/5), generalized epiphyseal ossification delay (3/5), and hypoplasia of basilar portions of ilea (3/5). Enzyme assessment showed α-iduronidase, α-mannosidase, β-glucuronidase, hexosaminidase A, and total hexosaminidase increased in plasma and normal glycosaminoglycans concentration. One patient was clinically classified as ML II and four patients as ML III. The follow-up of five patients showed the typical clinical and radiological findings allowing the diagnosis, thus improving clinical management and providing adequate genetic counseling. Clinicians and radiologists can take advantage of the information from this work, enhancing their differential diagnosis ability.

Entrance Region Heat Transfer in a Channel With a Ribbed Wall

Direct numerical simulation was performed for the heat transfer of airflow in the entrance region of a channel with repeated rib protrusions. The rib-pitch to rib-height ratio (Pi/H) was increased from 2.0 to 16.0 by four steps. The rib-height ratio (H/δ) was maintained constant at 0.20. The distribution of heat transfer coefficient numerically simulated agreed with the experiment by Kattchee and Mackewicz (1963, “Effects of Boundary Layer Turbulence Promoters on the Local Film Coefficients of ML-1 Fuel Elements,” Nucl. Sci. Eng., 16, pp. 31–38). The enhancement parameter was used to evaluate the heat transfer performance by a ribbed channel. This parameter was defined as the ratio of the mean Nusselt number for the ribbed channel against the smooth channel consuming the same pumping power. The simulation result revealed that the enhancement parameter was maximized for Pi/H = 2 to 4 over the upstream ribs (x/δ < 2) and was remained high for Pi/H = 4, 8, and 16 over the downstream ribs (x/δ > 4). Therefore, the optimal rib pitch was smaller for the upstream ribs, and increased to the developed region. The mechanisms underlying this trend were discussed through observation of the streamlines, mean temperature, turbulence statistics, and instantaneous structures. The turbulence was increased over the ribbed wall for the cases of medium to wide rib pitch (Pi/H = 4, 8, and 16), whereas the turbulence increase appeared only over the upstream ribs (x/δ < 2) for the cases of narrow rib pitch (Pi/H = 2). The excellent performance of the wider rib pitch (Pi/H = 4, 8, and 16) at the downstream ribs (x/δ > 2) was resulted from the turbulence increase activating the turbulent heat transport. Whereas, the superiority by the narrower rib pitch (Pi/H = 2, 4) comes from the turbulence activation, and the renewed thin boundary layer which continues due to the densely allocated ribs.

Direct Current Distribution Measurement of an Electrolyte-Supported Planar Solid Oxide Fuel Cell under the Rib and Channel by Segmented Electrodes

Solid oxide fuel cells have been of practical concern as a high efficiency power generation device. Problems of the SOFCs include current distribution that decays the total cell performance and efficiency, and causes electrode degradation chemically and thermo-mechanically. In the case of the planar SOFCs, the fuel/oxidant distributions and current collecting resistance cause current and temperature distributions over the electrodes under the separator ribs and flow channels. Optimized design of the separator is hence required to improve the power generation characteristics and durability of practical fuel cell stacks. Although there have been a number of numerical analyses, very few experimental investigations confirming in-situ current distributions to reveal the influence of the separator structure have been reported. The aim of the present study is thus to measure in-plane spatial current variations of an electrolyte-supported planar SOFC with segmented cathodes under the rib and the flow channel. We used the planar cell having three segmented cathodes (Fig. 1) assembled with segmented cathode separators for electrical insulation. The segmented cathodes were placed opposing to a rib and a set of parallel flow channels of the anode separator. The cell was composed of NiO-10Sc1CeSZ anode, 10Sc1CeSZ electrolyte, GDC interlayer, and LSCF-GDC cathode. The electrode area was 1.4 cm2(2.8 x 0.5 cm) each. The anode and cathode separator made of SUS430 had the flow channels with a width of 3 mm, a depth of 1 mm, and a length of 2.8 cm. Silver mesh was employed for the current collection of both sides. Current voltage (I-V) measurements were carried out under voltage control using three electric loads to reproduce the electrode potential of a single cell[1]. The anode and cathode were electrically connected with the four-terminal method. The anode NiO was reduced to Ni by feeding H2/N2 mixture gas for 2 hours prior to measurements. During measurements, anode and cathode were fed upward with mixtures of H2/N2and dried air at constant flow rates, respectively. The cell was maintained at 800 °C by an electric furnace at open circuit voltage (OCV) We prepared two types of the cathode separators. One of them had the same flow channel configuration as the anode separator where the rib and flow channels faces each other. The other had additional flow channels opposing to the anode rib. With the former cathode separator, the overpotential at the electrodes under the anode rib was significantly large compared with the flow channel part, whereas the latter case exhibited smaller overpotentials under the rib. This indicates that oxygen transport becomes poor under the wider rib in the cathode side. The latter case also indicated that the electrode under the rib exhibited smaller overpotential than the flow channel part when fuel is sufficient, owing to the smaller contact resistance under the rib by the compression. We also calculated current and hydrogen/oxygen partial pressure distributions by finite element simulation (COMSOL Multiphysics). The current distributions can be calculated so that they agree with the in-situ current distributions derived by the segmented cathodes from setting the exchange current densities, electrode porosities, electrolyte ion conductivities, and electrode ion/electron conductivities. Thereby oxygen starvation under the wider cathode rib and larger electron conduction resistance for the flow channel part were numerically evaluated to explain the in-situ currents for the segmented cathodes. We will present the results for the case of H2 starvation. [1] Ö. Aydin, T. Koshiyama, H. Nakajima, T. Kitahara, In-situ Diagnosis and Assessment of Longitudinal Current Variation by Electrode-Segmentation Method in Anode-Supported Microtubular Solid Oxide Fuel Cells, J. Power Sources, Vol. 279, 218–223 (2015).Fig. 1 Segmented cathodes on the planar SOFC. Figure 1

Regard typo-technologique sur les productions lithiques foliacées du Solutréen de la vallée de l’Erve (Mayenne, France)

Regard typo-technologique sur les productions lithiques foliacées du Solutréen de la vallée de l’Erve (Mayenne, France)

Semi-guided plane wave reflection by thin-film transitions for angled incidence

The non-normal incidence of semi-guided plane waves on step-like or tapered transitions between thin film regions with different thicknesses, an early problem of integrated optics, is being reconsidered. As a step beyond the common effective index picture, we compare two approaches on how this problem can be tackled—at least approximately—by nowadays readily available simulation tools for integrated optics design. Accepting the scalar approximation, using an ansatz of harmonic field dependence on the position along the interface, the 3-D problem reduces to a 2-D Helmholtz problem, for guided wave input and transparent-influx boundary conditions, with an effective permittivity that depends on the incidence angle. Alternatively, one complements the structure with a second mirrored interface, such that the 2-D cross section of a wide multimode rib waveguide emerges. Constraints for transverse resonance then permit to translate the propagation constants of its polarized modes into discrete samples of the phase changes experienced by an in-plane guided wave upon total internal reflection at the sidewalls.

CMOS-compatible, athermal silicon ring modulators clad with titanium dioxide

We present the design, fabrication and characterization of athermal nano-photonic silicon ring modulators. The athermalization method employs compensation of the silicon core thermo-optic contribution with that from the amorphous titanium dioxide (a-TiO(2)) overcladding with a negative thermo-optic coefficient. We developed a new CMOS-compatible fabrication process involving low temperature RF magnetron sputtering of high-density and low-loss a-TiO(2) that can withstand subsequent elevated-temperature CMOS processes. Silicon ring resonators with 275 nm wide rib waveguide clad with a-TiO(2) showed near complete athermalization and moderate optical losses. Small-signal testing of the micro-resonator modulators showed high extinction ratio and gigahertz bandwidth.

Behaviour of Steel-Concrete Composite Beam with High Ribbed Deck

Steel-concrete composite structures are structures that combine the advantages of both used materials. An advantage of such structures is their high bending resistance, which has a positive effect on the overall weight of the structure. The disadvantage could otherwise be a slightly complicated design of individual elements.The paper describes an experiment with two simply supported 6 m long steel-concrete composite beams loaded in their thirds. The each beam is made of standard steel rolled profile and concrete slab concreted into the transversally oriented trapezoidal metal sheet with rib height equal to 135mm, although European standard restricts the rib height only to 80mm for common use. The research is focused mainly on deflection of beam, whether partial or full shear connected and also deals with the possibility of modelling these structures using the finite elements method. The shear resistance of stud in narrow and wide concrete rib is investigated too.

Measuring the Current Distribution with Submillimeter Resolution in PEFCs: III. Influence of the Flow Field Geometry

The influence of the dimensions of the flow field’s channels and ribs on the local current generation at the submillimeter level and its correlation to the overall cell performance of polymer electrolyte fuel cells (PEFCs) were investigated. To measure the current and membrane resistance distribution on the scale of channels and ribs, the recently developed method, introduced and discussed in the first two parts of this series, was applied using the current drain in the cell as an internal shunt resistor. Current and membrane resistance distributions were evaluated for a series of geometries with systematic variations in channel and rib dimensions. The general picture deduced from the results shows that in cells with wide channels, even on the scale of millimeter and submillimeter dimensions, water transport limitations and thus local membrane resistance differences are dominating the local and integral performance. With the use of wide ribs, reactant mass transport becomes the dominant limitation in particular for low oxygen partial pressure conditions. These local loss mechanisms can be related to the gradients along the channel of a technical cell, leading to the idea of adapting the channel/rib dimensions along the flow path from the inlet to the outlet to provide an optimal geometry at every coordinate.

Cover Picture: Phys. Status Solidi C 6/7

AbstractThe article by Luigi Sirleto et al. on p. 1644 investigates an approach based on Raman scattering in porous silicon in order to overcome limitations inherent to the physics of silicon and to obtain light generation and/or amplification in this material. The design of a Raman amplifier in a porous silicon waveguide is proposed. The authors consider a monomodal channel waveguide having a 2 μm wide rib and a 2.15 μm thick core layer. The rib channel waveguide is defined by a lateral thickness of 1.4 μm. The thickness of the bottom layers is taken to be 1 μm.The cover picture shows the field profile of the pump beam; a similar profile is also obtained for the probe light. The field is well confined and the modal overlap between the pump and probe fields is excellent, as being necessary in order to achieve stimulated Raman scattering. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Fine embossing of chalcogenide glasses – a new fabrication route for photonic integrated circuits

For the first time embossing of ribs, from 1 to 10μm wide and ∼10mm long, has been carried out in chalcogenide glass layers sputtered onto semiconductor wafer substrates, with potential to act as monomode waveguides; these features have been similarly embossed in the surface of bulk chalcogenide glasses. The embossing shows very good replication of the GaAs mould patterning to 1μm definition, with evidence also for sub-micron replication. For the embossing, thin coatings of the chalcogenide glasses were sputtered onto wafer substrates as follows: (i) a 6μm layer of Ge17As18Se65 (at.%) onto porous Si-on-Si wafer substrates and (ii) a 4μm layer of Ge15As15Se17Te53 onto uncoated GaAs substrates. The Ge17As18Se65 sputtered glass layer on porous Si-on-Si was demonstrated to slab waveguide at 1.55μm wavelength; it was designed to achieve monomode waveguiding at 1.55μm after embossing, for the 5μm wide rib. The series of ribs, 1–10μm wide, were successfully embossed in the Ge17As18Se65 glass sputtered layer on porous Si-on-Si, but cracking of the glass layer occurred during the embossing process. Successful embossing of ribs without the glass layer cracking was achieved for the Ge15As15Se17Te53 sputtered glass layer on uncoated GaAs. Due to its relative simplicity, it is likely that hot embossing of this type of glass-based matrix offers an extremely promising route for producing high-resolution, guided-wave optical components and circuitry at low-cost, high-volume, and for a wide wavelength range.