Ridge Shape Research Articles

A Histomorphology Comparison of Saw-Tooth Shaped Rete Ridge Between Oral and Cutaneous Lichen Planus

Lichen planus is chronic and comparatively collective inflammatory mucocutaneous disease. The histopathological features of oral lichen planus were described as comparable to those of cutaneous lichen planus(CLP). Among those saw-toothed rete ridges are introduced as less important histopathologic features of idiopathic OLP in contrast to CLP. Accordingly, existing study aimed to estimate existence of saw tooth rete ridges in OLP in comparison to CLP.; In this retrospective cross-sectional study, 56; E stained slides with clinical and histopathological diagnoses of OLP were randomly collected from the archive of the oral pathology laboratory. CLP cases were selected randomly from a private pathology laboratory and were evaluated for the presence of saw-toothed rete ridges. Collected data were evaluated using Chi-square; Fishers exact test in SPSS 24 at an error level of 0.05%. Chi-square test did not show a substantial difference between oral; cutaneous groups in terms of the shape of the rete ridges (p = 0.511). Outcomes of existing study showed that saw tooth rete ridge was seen in OLP similar to CLP. Future studies concerning clinical subtype and type of keratosis are recommended.

Study of Morphometric Analysis of Acetabulum and Its Clinical Correlation in South Indian Population

Introduction: Acetabulum is a cup shaped cavity on the outer surface of the constricted central part of the hip bone, where three components meet and subsequently fuse. In modern world, orthopaedic surgeons and biomedical engineers are trying to make the best possible prosthesis for planning the total hip replacement. Body proportion and absolute dimension vary widely in respect to age, sex and racial groups. While partially due to variability in muscularity and adiposity, such variations are chiefly in skeletal system. Purpose of study: The main intention of this study was to obtain the morphometric data of acetabulum. This data suffices the mechanics of the hip joint so as to plan for suitable prosthesis and various surgical approaches. Material and method: The study was conducted in the department of Anatomy. Hundred hip bones of both sexes were used. In this study we included only healthy adult bones, deformed and eroded bones were excluded from the study. The osteometric parameters such as diameter, depth and capacity of acetabulum, notch width and shape of the anterior acetabular ridge were measured using digital Vernier calipers and measuring jar. The data was analysed statistically using SPSS software. Results: The mean diameter of acetabulum in males was found to be 5.03 cm and in females it was 4.44 cm, whereas on right side it was 4.70 cm and on left side it was 4.77 cm. The mean depth of acetabulum in males was 2.85 cm and in females it was 2.49 cm, whereas on the right side was 2.71 cm and 2.63 cm on the left. The mean notch width of the acetabulum in males was 2.07 cm and in females it was 1.71 cm, whereas on the right side it was 1.92 cm, and 1.85 cm on the left. Total range for the acetabular capacity was 22-30.68 ml. The curved shape anterior acetabular ridge was the most predominant type (39%) and the least type was irregular shaped (15%). Conclusion: The acetabular parameters such as acetabular diameter, depth, capacity and notch width of the acetabulum was greater in males compared to the females. Statistically the comparison was highly significant. Most common anterior acetabular ridge shape is curved type (39%), least was Irregular type (15%). Morphometric data of acetabulum is essential for clinical correlation and it also helps in the detection of disputed sex by Forensic experts. It also helps the orthopaedic surgeons for planning the total hip replacement KEY WORDS: Hip bone, Acetabular Diameter, Acetabular Depth, anterior ridge, Notch.

Research on the wear and corrosion resistance of Ni–GO–TiC composite coating by scanning jet electrodeposition

The Ni–GO–TiC nano-composite coating was prepared by scanning jet electrodeposition. The morphologies and microstructures of the composite coating were analyzed by FESEM and XRD, and the wear and corrosion resistance of the composite coating were studied. Studies have shown that the Ni–GO–TiC composite coating has some ridge shape structures. The addition of nano TiC and GO does not change the structure but refines the grain growth of the Ni matrix metal. Nano TiC can effectively prevent GO from agglomerating, improve the dispersion, and further enhance the wear resistance of the Ni–GO–TiC composite coating. In addition, the microhardness and corrosion resistance of the Ni–GO–TiC composite coating has also been greatly improved. The hard nano TiC reinforcement proposed in this study helps to improve the comprehensive properties of nickel-based graphene oxide composite coatings, and provides a new method reference for subsequent research on nickel-based composite coatings.

Evaluation of Soil Water Movement and Consumption at a Welsh Onion Field with Changing Ridge Shape

Evaluation of Soil Water Movement and Consumption at a Welsh Onion Field with Changing Ridge Shape

ANALYSIS OF THE EFFICIENCY OF ACOUSTIC SCREENS OF DIFFERENT DESIGNS

Various sources of noise in cities and ways to combat them are considered. The effi ciency of two types of acoustic screens is analyzed: single-layer and two-and three-layer. The positive and negative characteristics of various designs of existing acoustic screens are listed. A fundamentally new design of the acoustic screen is described: the panels have a ridge profi le, they are located along the vertical axis of the frame with a step at which the panels above the located ridge cover the top of the lower ridge, the outer surfaces of the panels and their end parts are made of a material that has sound-refl ecting properties, and the inner surfaces of the panels are made of sound-absorbing material. Such an acoustic screen is devoid of the disadvantages inherent in acoustic screens of other structures and is more effi cient. The considered invention allows due to the use of the ridge shape of acoustic panels: prevent the refl ection of sound energy in the direction of noise sources (a small part will be directed upwards); provide almost complete absorption of sound energy as it passes through the channels formed by the ridge panels; provide the same effective protection against noise sources located on both sides of the screen; prevent the formation of snow and ice crust on sound-absorbing surfaces, which ensures the constant eff ectiveness of the screen in diff erent seasons of the year; reduce metal consumption, which will reduce the weight of the structure without reducing its effi ciency and reduce the cost of acoustic screens.

Bayesian credible intervals for population attributable risk from case–control, cohort and cross‐sectional studies

SummaryPopulation attributable risk (PAR) and population attributable fraction (PAF) are used in epidemiology to predict the impact of removing a risk factor from the population. Until recently, no standard approach for calculating confidence intervals or the variance for PAR in particular was available in the literature. Previously we outlined a fully Bayesian approach to provide credible intervals for the PAR and PAF from a cross‐sectional study, where the data was presented in the form of a 2×2 table. However, extensions to cater for other frequently used study designs were not provided. In this paper we provide methodology to calculate credible intervals for the PAR and PAF for case–control and cohort studies. Additionally, we extend the cross‐sectional example to allow for the incorporation of uncertainty that arises when an imperfect diagnostic test is used. In all these situations the model becomes over‐parameterised, or non‐identifiable, which can result in standard ‘off‐the‐shelf’ Markov Chain Monte Carlo (MCMC) updaters taking a long time to converge or even failing altogether. We adapt an importance sampling methodology to overcome this problem, and propose some novel MCMC samplers that take into consideration the shape of the posterior ridge to aid in the convergence of the Markov chain.

Effect of topographic background on sand wave migration on the eastern Taiwan Banks

Observational analysis has revealed an apparent immobility of giant sand waves on the Taiwan Banks, while sand waves on the eastern Taiwan Banks show distinct dynamics influenced by the underlying larger-scale sand ridge bedforms. In this study, the effects of these sand ridge bedforms on sand wave migration and the local hydrodynamic environment were investigated using bathymetric and hydrodynamic datasets from 2016 and 2018. Upon separating the NNW-SSE sand ridge crest, the opposing sand wave migration and complementary sediment loss/gain on either side of the sand ridge are interpreted as convergence processes that serve to maintain the shape of the sand ridge. Analysis of the hydrodynamics revealed that, during the flood phase, the northward directed flow on the western side of the ridge crest was enhanced due to rapid shoaling. This caused the development of a flow shadow zone on the eastern side of the ridge crest, where the flow was rotated and weakened. During a tidal cycle, the dominance of the flood current on the western side of the ridge resulted in northward migration of sand waves. Conversely, due to the weakened flood current on the eastern side of the ridge, sand waves migrated southward in response to the stronger ebb current. This study thus provides insights into bedform dynamics in complex morphological settings and the maintenance mechanism of morphodynamic bedform systems.

Rotating microstructured spinnerets produce helical ridge membranes to overcome mass transfer limitations

Membrane geometry evolution boosts membrane applications to become even more sustainable, resource- and energy-efficient. This evolution is crucial as increasingly permeable membrane materials introduce the major drawback of promoting fluid resistance due to boundary layer formation. We present how to break these boundary layers with Helical Ridge Membranes produced by rotating microstructured spinnerets. 3D printing enables us to manufacture polymeric, microstructured spinnerets featuring grooved orifices. When integrating these spinnerets into a wet spinning process, microstructured hollow fiber membrane surfaces evolve. Our home-engineered spinning technology sets the spinneret in motion. Rotation twists the nascent microstructure and creates a helical ridge on the lumen side. A robust spinning process especially establishes for our novel spinneret device to rotate the needle inside the spinneret. The interplay of spinning conditions and spinneret rotation uncovers a range of producible helical ridge shapes, sizes and pitches. In addition, spinneret rotation speed affects intrinsic membrane properties, about which we derive general correlations. The helical ridges prove the manipulation of hydrodynamics inside hollow fiber membranes by inducing secondary flow. The latter enhances mass transfer to diminish boundary layers. Ultimately, a cross-flow ultrafiltration showcase reveals TMP gradients reduced by 350% and demonstrates the disruptive impact of Helical Ridge Membranes on membrane filtration.

Effect of Mechanical Properties on Multicomponent Shell Patterning.

Self-organized shells are fundamental in biological compartmentalization. They protect genomic material or enclose enzymes to aid the metabolic process. Studies of crystalline shells have shown the importance of the mechanical properties of building units in the shell morphology. However, the mechanism underlying the morphology of multicomponent assemblies is still poorly understood. Here, we analyze multicomponent closed shells that have different mechanical properties. By minimizing elastic energy, we show that heterogeneous bending rigidities regulate the surface pattern into circular, spikes, and ridge shapes. Interestingly, our continuum elasticity model recovers the patterns that have been proposed in bacterial microcompartments (BMCs), which are self-organized protein shells that aid the breakdown of complex molecules and allow bacteria to survive in hostile environments. In addition, our work elucidates the principles of pattern formation that can be used to design and engineer multicomponent microcompartments with a specific surface distribution of the components.

Investigation of Tactile Perception Evoked by Ridged Texture Using ERP and Non-linear Methods.

The triangular ridged surface can improve the grip reliability of products, but the sharp edge of triangular ridge induces sharp and uncomfortable feeling. To study the effect of edge shape (sharp, round, and flat shape) of triangular ridges on brain activity during touching, electroencephalograph (EEG) signals during tactile perception were evaluated using event-related potentials (ERP) and non-linear analysis methods. The results showed that the early component of P100 and P200, and the late component of P300 were successfully induced during perceiving the ridged texture. The edge shape features affect the electrical activity of brain during the tactile perceptions. The sharp shape feature evoked fast P100 latency and high P100 amplitude. The flat texture with complex (sharp and flat) shape feature evoked fast P200 latency, high P200 amplitude and RQA parameters. Both of the sharp shape and complex shape feature tended to evoke high peak amplitude of P300. The large-scale structures of recurrence plots (RPs) and recurrence quantification analysis (RQA) parameters can visually and quantitatively characterize the evolution regulation of the dynamic behavior of EEG system along with the tactile process. This study proved that RPs and RQA were protential methods for the feature extraction and state recognition of EEG during tactile perception of textured surface. This research contributes to optimize surface tactile characteristics on products, especially effective surface textures design for good grip.

Normal Anatomy of the Lumbar Sublaminar Ridge in the Lateral Recess with Potential Implications to Surgical Technique in Degenerative Spinal Stenosis: A Cadaveric Study.

This is an anatomic study using cadaveric material. To provide anatomic descriptions of the normal lumbar sublaminar ridge in the lateral recess and its potential to impact on the exiting nerve root there, with implications to surgical technique in lumbar spinal stenosis. The lateral extent of the sublaminar ridge-the bony, superior insertion site of the ligamenta flava-and its topological relationship to the nerve root are not described in the literature. In the setting of degenerative lumbar stenosis this structure can hypertrophy and impinge the nerve root within the lateral recess even after excision of the corresponding ligamentum flavum. Failure to address this may contribute to failed lateral recess decompression. Fifteen lumbar vertebrae, not obviously degenerated, were resected en bloc from three fixed adult human cadavers and then transected through the pedicles, leaving the posterior column and neural elements intact and articulated. The shape of the sublaminar ridge in the lateral recess and its relationship to the exiting nerve root were carefully examined. The exiting nerve root consistently crosses the sublami- nar ridge immediately inferior to the mid-pedicle, lateral to the subarticular gutter, and on the medial aspect of the true intervertebral foramen. A hypertrophic ridge can compress the exiting root by elevating the nerve root superiorly against the bony underside of the pedicle or displacing it anteriorly against the disc or vertebral body. The sublaminar ridge in the lateral recess may contribute to degenerative lumbar stenosis. Comprehensive appreciation of this anatomy may facilitate thorough lateral recess decompression.Level of Evidence: 4.

Application of Bovine Acellular Cancellous Bone Matrix in Alveolar Ridge Preservation Following Tooth Extraction

Objective: In this article, we explored the microscopic structure and composition of the decellular-ized cancellous bone matrix of the calf, and established the animal model of Beagle dog extraction. By applying different bone substitute materials in the extraction of teeth, we observed the new collagen-rich in the preservation of the site after tooth extraction. The protein bone matrix maintained the three-dimensional shape of the alveolar ridge compared to other biological materials. Methods: The microstructure of the new collagen-rich bone matrix was observed by scanning electron microscopy. The porous structure, porosity and distribution of collagen fibers were observed. XRD and infrared spectroscopy were used to further detect the inorganic and organic components in the new collagen-rich bone matrix. The premolar extraction and site preservation model of Beagle dogs were constructed. The changes of collagen-rich bone matrix, Bio-oss bone powder, CGF filling and blank control alveolar ridge volume were compared by CBCT. HE staining was used to observe and compare new bone formation, bone remodeling and bone resorption between groups, and to observe the formation of blood vessels, osteogenic mineralization, trabecular bone formation and inflammatory response in different periods. Results: (1) The acellular bone matrix of bovine cancellous bone completely removes the immunogenicity of the cells and has good histocompat-ibility; the pore diameter and porosity closest to the physiological structure, the main component is hydroxyapatite and collagen. (2) Site preservation can reduce the absorption of alveolar ridge following tooth extraction, preserve sufficient bone mass for alveolar fossa, and retain a good width of attachment, which provides further protection for implant surgery. (3) In the post-extraction site preservation, the CGF group has better bone composition than the BABM group and Bio-oss bone powder. Conclusion: Bovine Acellular Cancellous Bone Matrix is a new type of biological bone matrix. The main components are collagen and hydroxyapatite, which can promote bone formation in the extraction socket.

Role of Marginal Ridge Shape and Contact Extent in Proximal Caries Between Primary Molars.

To determine different combinations of marginal ridge shape (MRS) and contact extents in nature of the contact between primary molars and its correlation with the presence of carious lesions on radiographic examination of approximal surfaces. Retrospective study of 347 clinical records, including photographs and bitewing radiographs, were assessed for intact MRS and caries extent. The carious lesions were scored (0-5, Mejàre scoring system) radiographically and correlated to the intact MRS on clinical photographs, and strength of associations quantified using logistic regression analysis and chi-square tests. Primary molars, 848(contact extent), and 757(MRS) were analyzed. Combination of straight-convex(35.4%) MRS was more common (p<0.001). None of the approximal surfaces were caries-free for straight and straight MRS with 36.4% of both approximal surfaces exhibiting caries in enamel, and 38.2% of one approximal surface exhibiting caries in dentin. Approximately 90% of the primary molars with substantial contacts exhibited carious lesions in the enamel and 80% with light contacts exhibited carious lesions in the dentin (p<0.001). Six different combinations of intact MRS were identified. Combination of concave-convex shapes exhibited caries extending into dentin. Substantial and/or light contacts between primary molars showed higher caries experience in the approximal surfaces.

Association between ridge morphology and complexity of implant placement planning in the posterior mandible

Statement of problemUncertainties regarding the 3D ridge morphology of the posterior mandible can greatly increase the risk of surgical complications during dental implant placement. By using cone beam computed tomography (CBCT) imaging and a computer-guided implant treatment software program before any invasive procedure, it is possible to assess ridge morphology and understand the surgical complexity and risk level. PurposeThe purpose of this radiological clinical study was to evaluate a large series of CBCT images to evaluate ridge shape variations along posterior mandibular edentulous regions and to clarify their associations with the level of implant planning complexity. Material and methodsOne hundred and twenty CBCT files were analyzed retrospectively for a total 240 hemimandibular sites. Images of each edentulous region of the mandibular first and second premolar and first and second molar sites were evaluated in the sagittal plane. Ridge morphology and implant planning complexity per site were assessed. Categorical variables were presented as number of events and percentages. The chi-square test was used to compare the categorical variables (P=.05). ResultsOf 491 partially edentulous mandibular sites, 235 were on the right, and 256 were on the left. Forty-two sites had a distal adjacent tooth, while 266 sites had no distal adjacent tooth. The sagittal bone sections demonstrated oblique (40.53%), straight (31.77%), S-shape (24.24%), hourglass (2.44%), and basal bone (1.02%) ridge morphologies. Implant complexity was deemed straightforward in 66.19% of sites, while 31.6% were identified as advanced and 2.54% as complex. When ridge morphology was evaluated from straight to basal-round bone shape, the implant complexity followed the same trend of change from a straightforward to complex procedure (P=.001) for edentulous second and first molar regions. No significant differences were noted at edentulous second premolar sites (P=.063). The missing second molar sites with oblique morphology were predicted to have 60.9% straightforward complexity, and first molar sites with oblique morphology had 55.8% straightforward implant complexity. Second premolars with straight ridge morphology had 71.7% straightforward complexity, whereas first premolars with the same shape had 92.5% straightforward implant complexity. ConclusionsCareful evaluation of sagittal CBCT images can provide significant clinical information regarding ridge shape and anticipated surgical complexity before and at the time of implant placement. Surgical complexity is greatest at the most posterior mandibular edentulous sites, and extra attention and caution should be exercised during the surgical planning phases of implant surgery.

Effect of changing geometrical characteristics for different shapes of a single ridge passing through elastohydrodynamic of point contacts

Purpose The purpose of this paper is to study the behavior of a single ridge passing through elastohydrodynamic lubrication of point contacts problem for different ridge shapes and sizes, including flat-top, triangular and cosine wave pattern to get an optimal ridge profile. Design/methodology/approach The time-dependent Reynolds’ equation is solved using Newton–Raphson technique. Several shapes of surface feature are simulated and the film thickness and pressure distribution are obtained at every time step by simultaneous solution of the Reynolds’ equation and film thickness equation, including elastic deformation. Film thickness and pressure distribution are chosen to be the criteria in the comparisons. Findings The geometrical characteristics of the ridge play an important role in the formation of lubricant film thickness profile and the pressure distribution through the contact zone. To minimize wear, friction and fatigue life, an optimal ridge profile should have smooth shape with small ridge size. Obtained results are compared with other published numerical results and show a good agreement. Originality/value The study evaluates the performance of different surface features of a single ridge with different shapes and sizes passing through elastohydrodynamic of point contact problem in relation to film thickness and pressure profile.

Morphologic and Morphometric Study of Human Acetabulum and its Clinical Significance

Introduction: The acetabulum is a cup shaped hemispherical depression which is present on the hip bone, contributed by ilium, ischium and pubis. It has a central depressed non-articular part called acetabular fossa, surrounded by a curved lunate articular surface which articulates with the head of femur to form hip joint. The knowledge of acetabular dimensions assists the radiologists in diagnosing acetabular dysplasia and aids the surgeon to determine the correct size of the acetabular cup during total hip arthroplasty and to realign the acetabulum back to normal position. Aim: To measure and analyse the relationship between the depth and diameter of acetabulum and also to study the variations in the morphology of anterior acetabular ridge. Materials and Methods: A cross-sectional study was done on 104 unpaired dry human adult hip bones from February 2017 to September 2019 after obtaining ethical clearance. The diameter and depth of acetabulum was measured using vernier calliper and a metallic strip and correlation between them were analysed using Pearson’s test. Student’s t-test was used to test the significance between the variables. The p-value &lt;0.05 were considered as statistically significant. The different shapes of anterior acetabular ridge were noted. All the recorded data were analysed using Statistical Package for the Social Sciences (SPSS version 16.0). Results: The average measurements of acetabular diameter and depth were 48.98±2.91 mm and 24.12±2.54 mm, respectively. A positive and a significant correlation was found between diameter and depth of the acetabulum (r=0.388, p&lt;0.001). The mean values of diameter and depth of acetabulum in right side were 48.76±2.94 mm and 23.6±2.48 mm, respectively. The average values of diameter and depth in left side were 49.2±2.92 mm and 24.6±2.59 mm, respectively. Though the measurements of acetabular dimensions on left side were slightly greater than right side, they were not statistically significant (p&gt;0.05). Four different shapes of anterior acetabular ridges were noted: angular (23.08%), curved (63.46%), straight (2.88%) and irregular (10.58%). Conclusion: The present study showed weakly positive correlation between diameter and depth of the acetabulum and morphological variations in the shape of anterior acetabular ridge.

Contact lines on stretched soft solids: modelling anisotropic surface stresses

We present fully analytical solutions for the deformation of a stretched soft substrate due to the static wetting of a large liquid droplet, and compare our solutions to recently published experiments (Xu et al. 2018 Soft Matter 14, 916–920 (doi:10.1039/C7SM02431B)). Following a Green’s function approach, we extend the surface-stress regularized Flamant–Cerruti problem to account for uniaxial pre-strains of the substrate. Surface profiles, including the heights and opening angles of wetting ridges, are provided for linearized and finite kinematics. We fit experimental wetting ridge shapes as a function of applied strain using two free parameters, the surface Lamé coefficients. In comparison with experiments, we find that observed opening angles are more accurately captured using finite kinematics, especially with increasing levels of applied pre-strain. These fits qualitatively agree with the results of Xu et al ., but revise values of the surface elastic constants.

The shape of the left lateral ridge as a predictor of long-term outcome of catheter ablation for atrial fibrillation based on clinical and experimental data

BackgroundThe left lateral ridge (LLR) is an important structure for ablation of atrial fibrillation (AF). This study assessed how the LLR shape is associated with the long-term outcomes of AF ablation and investigated the relationship with radiofrequency (RF) lesion formation. Methods and resultsClinical study - we assessed multi-detector computed tomography (MDCT) images in 247 patients who underwent AF ablation. Patients were classified into two groups according to the shape of the LLR: Narrow LLR group (n = 116; 47%) and Wide LLR group (n = 131; 53%). After a follow-up period 475 ± 245 days, the AF-free rate was significantly higher in the wide LLR than Narrow LLR group (83.2% vs. 62.9%, p = 0.0004). A multivariate analysis showed that the shape of the LLR was an independent predictor of AF recurrence after ablation (hazard ratio 2.58; 95% confidential interval = 1.48–4.51, p = 0.001).Experimental study - Two types of the ridge models were made with porcine atrial tissues: “Narrow ridge(4.2 ± 0.9 mm)” and “Wide ridge(9.7 ± 1.8 mm)” RF ablation was performed on each ridge model using a contact force (CF)-sensing catheter. The mean CF and the RF lesion volume of the narrow ridge were significantly less than those of the wide ridge model (5.42 ± 3.13 g vs. 10.37 ± 3.98 g, p = 0.001; 19.8 ± 9.9 mm3 vs. 44.2 ± 13.6 mm3, p < 0.001, respectively). ConclusionsAF recurrence after ablation was more frequent in patients with a narrow LLR. LLR shape as assessed using MDCT is associated with long-term outcomes after AF ablation. CF and lesion formation data using the porcine atrial tissue model support our clinical results.

Development of high performance and low noise axial-flow fan for cooling machine room of refrigerator using airfoil-cascade analysis and surface ridge shape

Development of high performance and low noise axial-flow fan for cooling machine room of refrigerator using airfoil-cascade analysis and surface ridge shape

Leaky Bloch modal evolution of wideband reflectors with zero-contrast gratings from symmetric trapez to triangle ridge shapes

We treat wideband subwavelength guided-mode resonant gratings with grating-depth dependent duty cycles. By rigorous numerical computations, we visualize Bloch modal evolution while transforming the grating profile from trapezoid to triangle. Parametric optimization is achieved using the coordinate transformation method of Chandezon. With the increase of the profile base angle, the higher mixed resonant modes TM1 , 1 & 2 attract and combine and interact with the modes at both sides, forming wide reflection bands. This modal combination and interaction are the key determinant of broadband reflectivity spectral location and width. The optimized structure exhibits 99% reflectivity across a 613-nm spectral range, spanning a 1438- to 2051-nm wavelength range with a fractional bandwidth of ∼35 % . It is shown that gratings with trapezoidal profiles possess a good tolerance to groove depth variation, thus being easier to fabricate with a diamond-tip than triangular profile-based gratings.