This study is an investigation of weight fraction (wt%) and fiber feedstock length (FFSL) effects on the bearing strength (BS) of bolted joints in glass-fiber-reinforced (GFR) polypropylene (PP) composites manufactured by an injection molding technique. The investigation was made for holes produced either by molding or machining. For machined holes, the effect of drilling parameters (feed and speed) on BS was discussed. It is observed that BS decreased as FFSL increased. BS of both molded-in and drilled specimens was enhanced by increasing wt% of glass fiber. While slightly better BS was observed for molded-in specimens than drilled ones for all specimens. The drilling conditions’ effect on BS was found to be insignificant for drilled holes in long fibers reinforced PP, where the most significant factor was wt%. However, for short fibers reinforced PP, the spindle speed was the most significant factor followed by feed, while wt% has the lowest effect. Failure morphology mode for specimens indicates that for molded-in specimens, neat PP specimens failed under pure bearing mode while GFR/PP specimens failed under the mixed-mode failure (bearing and net tension). For machined specimens, all specimens failed under mixed-mode failure except for the highest wt% specimens which failed under net tension. The addition of fibers is widely used in reinforcing polymeric-based composites to be more reliable in their applications. In order to use fiber-reinforced polymers (FRPs) as a structural element, these materials have to fulfill some requirements such as stiffness, strength, durability, impact and crush to be more useful in the manufacturing and assembly of critical components2. Various automobile parts have been produced using fiber-reinforced thermoplastics, as their lightweight effects have been demonstrated by non-load bearing4 and semi-load bearing parts. These parts include battery boxes7, crash boxes8, lightweight wheels9, front-end modules10, automotive seats12, leaf springs13, and hoods14. In particular, GFR/PP appears to have a good potential for application in the building of prefabricated structures such as houses, barriers, beams, and bridge decks in the field of civil engineering15. Vaidya and Chawla16 designed and fabricated a durable bus seat made of GFR/PP providing 43% and 18% savings, respectively, in weight and total production cost compared to commonly used seat designs.Recently the usage of thermoplastic materials has been increasing steadily as they provide a unique collection of properties. Strength-to-weight ratios, environmental resistance, rapid processing, superior high-temperature performances, and recyclability are some of thermoplastics’ advantages that favor their use over other materials23. The joint strength of GFR/PP was found to be suitable for the design of the leaf spring and hence these types of materials can be utilized for joint applications26. Also, Anandakumar et al.27 obtained a superior performance from GFR/PP control arm, as a load-bearing component of the suspension system, in comparison to steel. The joint design has a particular interest in FRPs structures since joints represent the weakest point in a composite structure and the composite material capability of redistributing local high stresses through yielding20. BS is an important property that must be taken into consideration in joint design.The joints represent one of these critical components where bolts provide the primary means of connecting FRPs in the structural application, construction of aircraft, aerospace, automotive vehicles, and other engineering applications with high performances including sporting goods, wind energy structures, and medical appliances28 explained that drilled holes significantly reduced the performance of Carbon fiber/epoxy composite due to a through-the-thickness cut of fibers which can be averted by using molded-in holes. Nejhad and Chou29 considered that for all practical purposes, a molded-in hole is more desirable than a drilled hole. Therefore, many alternative hole molding techniques were developed. Hufenbach et al.30 used a technique based on fiber shifting which enables non-destructive manufacturing of the holes. Brookstein and Tsiang31 found that integrally-formed braided holes provide a 180% increase in joint BS compared with machined holes in the graphite fibers/epoxy composite. Chang et al.32 showed in a study of mechanical joining by pin load of Kevlar/epoxy, Graphite/epoxy, and Kevlar-Graphite/epoxy hybrid composites that specimens with molded-in holes gave 0.12–61.23% strength enhancement compared with drilled hole specimens.The holes needed for joining FRPs are usually manufactured by the drilling process which weakens the reinforcement structure. Nejhad and Chou33 showed that there exists larger failure strength, smaller initial stiffness, and larger failure strain of woven glass roving composite s with a molded-in hole relative to those with a drilled hole. However, for s there is no improvement for failure strength and initial stiffness except for failure strain. Zitoune et al.34 observed that molded-in holes of woven carbon fibers/epoxy composite exhibit 30% higher strength and 100% lower strain than drilled holes. Brown et al.35 showed that for advanced manufacturing of carbon fiber/PEEK thermoplastic composites, better open-hole tensile and compressive properties were obtained when holes were produced by thermally assisted piercing technique as compared with drilled holes. Fujita et al.36 found that for the braided glass fiber reinforced epoxy composite (GFRE), the joint strength of the braided hole was greater than that of the machined hole. Also, Herszberg et al.37 found that weft-knitted and woven glass fiber/epoxy composites with integrally formed holes had a BS about 20% greater than those with drilled holes. Durante and Langella38 found a high BS of the GFRE composite specimens with the molded-in hole, made by shifting the fibers around the hole, compared to the BS of the specimens with holes made by cutting the fibers by drilling. Dickson and Dowling39 found that the BS of 3D printed Carbon fiber/Nylon composite with a drilled hole is lower than that of the ‘Tailor Woven’ integrated hole by 63% if it goes under double shear testing. Clark40 concluded that the average increases in bearing stress and bearing strain at failure of cut carbon fibers/Nylon composites for the printed-in holes  compared with the drilled-in holes were 31% and 86.8%, respectively.Experimental results of Lin et al.41 concluded that the BS of the Tri-axial braided carbon fiber/epoxy specimens with a molded-in hole was reduced than specimens with drilled holes, due to the increased misalignments of the fibers during the manufacturing process. Wang’s42 comparison between holes produced by tri-axial braided glass roving/epoxy specimens and machined holes indicated that the braided hole showed similar or even lower bearing capacity compared with the machined hole.On contrary, Ataş et al.21 found that specimen stiffness and BS of GFRE decreased as the feed rate and cutting speed increased. Khashaba and El-Keran43 observed a lower BS of woven GFRE composites that were drilled at a speed of 16.3 m/min compared with drilling at 32.7 m/min while feed values had an insignificant effect on BS at speed of 16.3 m/min but it had a clear effect at 32.7 m/min (increased then decreased). Krishnaraj et al.44 illustrated that drilling at a rotational speed of 3000 rpm and a feed rate of 0.02 mm/rev led to the highest BS compared to other spindle speeds and feeds. Tagliaferri et al.45 concluded that for a given drilling speed to feed rate ratio, better results in terms of BS may be obtained by adopting a lower drilling speed for GFRE specimens. Srinivasa Rao et al.46 found that small feed rates are preferred in the drilling of woven GFRE composite laminates. Wang et al.47 indicated that both rotational speed and feed when drilling GFRE laminates had an insignificant effect on the BS.For machined holes, the BS of FRPs with drilled holes was mainly affected by the machining conditions. Khashaba et al.48 discussed the damage caused by drilling in unidirectional composites made with thermoplastic matrix reinforced with graphite fibers concerning different machining parameters. Hocheng and Puw50 demonstrated that the carbon-fiber-reinforced Acrylonitrile Butadiene Styrene (ABS) composites had good machinability in drilling compared with epoxy-based composites. Mudhukrishnan et al.51 discussed the effect of drill material, spindle speed, and feed rate on delamination and thrust force on woven glass fabric reinforced polypropylene laminates.Studies dealing with the drilling of thermoplastic matrix composites cover some aspects where Ilio et al.52. Despite reinforcing injection molded parts with continuous fibers is not possible, holes could be reinforced using embedded local continuous fibers52. Moreover, an allowance of improving joint performance by metallic insert is possible through injection molding54, where direct adhesion between the plastic and the metal could be secured55.Manufacturing parts with readymade holes requiring no further processing distinguishes injection molding from other manufacturing techniques. Injection molding can flexibly provide thermoplastic constructions reinforced with short fibers as an enhancement for strength including joint strength. However, there are limits to joint strength enhancement through increasing shot fiber content. Also, rare studies were carried out in the comparison between the BSs of molded-in holes and drilled holes of this type of material. Moreover, there is no systematic study carried out to indicate the effect of machining conditions on the BS for such type of materials. Accordingly, the present work aims to study the effect of change in weight fraction of glass fiber on the BS of injection-molded chopped glass fiber reinforced thermoplastic (PP) composites. An investigation was made to compare between the BS of molded-in and drilled holes of these type of composites. Moreover, the influence of drilling parameters  on BS of specimens with machined holes was studied.From the previous literatures it has been clear, according to our knowledge, that limited research works are concerned with studying the effect of weight fraction on the BS of injection-molded chopped glass fiber reinforced thermoplastic composites®—Egypt. Glass fiber (GF) used in the present work was E-glass chopped strands with filament chop lengths of 12 and 24 mm and were supplied by JUSHI Co. Mechanical and physical properties of GF and PP are presented in Tables The matrix material used in this work was Polypropylene (PP) copolymer for injection molding 413MNK45) which was supplied by SABIC3MNK45 whSpecimens for the bearing test were manufactured using plastic injection molding using HAITIAN PL1200 injection molding machine with a maximum clamping force of 1200 KN. The mold was designed, manufactured, and examined several times to check its suitability for producing the desired specimens according to ASTM D5961 standard for bearing specimens. In this mold, the same direction of the flow for the plastic is considered for each specimen to avoid the probability of weld lines formation which may lead to cracks.The mold is provided with two 6 mm diameter inserts; short and long inserts. The short insert is used for specimens without molded-in holes (the holes will be drilled later using the machining process), Fig. To produce the test specimens, the barrel temperature profile along the injection-molding machine was adjusted to be 140, 160, 180, 220, and 244 °C. The barrel temperature was adjusted during the process when adding PP with GF. The manufacturing process can be described as follow; First, neat PP bearing specimens were injection molded. Second, PP pellets were mechanically blended with GF using different weight fractions of 10, 20, and 30 wt% of PP and different feedstocks having fiber lengths of 12 mm and 24 mm. The mixture was first fed to an extruder of the injection molding machine to produce pre-samples. Pre-samples with their sprue and runners are crushed in a crusher forming small particles of identical sizes. The small particles were injection molded once again to obtain the final test specimens. The main purpose of these stages is to gain a better distribution of the GF into the PP. The whole process is repeated with a long insert added to the mold to produce specimens with molded-in holes. The manufactured specimens had chopped and randomly oriented fibers. The codes and compositions of specimens manufactured with molded-in holes are illustrated in Table i CNC milling machine equipped with Boxford pc software. A manual vise is used to hold and consistently locate the workpiece. A 6 mm diameter carbide twist drill bit (as recommended in the drilling of GFR/PP by Mudhukrishnan51) provided by AYKT is used in the drilling process. The drilling process was conducted in dry conditions without the use of coolant. Drilling was performed with the support of a wooden plate at the back of the composite samples. The experimental factors at different levels were designed using the Taguchi method as shown in Table The drilling process was performed using a Boxford 300VMCFull factorials design of experiments identifies all possible combinations for a given set of factors. Since most industrial experiments usually involve a significant number of factors, a full factorial design results in more experiments. To minimize the number of experiments to a reasonable level, only a small group from all the possibilities is chosen. Taguchi analysis offers a unique set of design guidelines that cover several aspects of factorial experiments. The experimental design by the Taguchi method involves orthogonal arrays organizing the process parameters and possible variation levels. It determines the factors that affect product quality the most with minimized experimentations, thus saving resources and time. In the present work, the factors of the drilling process are fiber weight fraction, spindle speed, and feed rate. The levels of fiber weight fractions were 0, 10, 20, and 30 wt%. The selected levels of cutting speeds were 1000, 2000, 3000, and 4000 rpm. While levels of feed rate were taken as 100, 200, 300, and 400 mm/min. These factors and their levels are shown in Table The drilling experiments were performed using the L16 mixed orthogonal array including 16 runs corresponding to several tests for Taguchi’s method. The experimental layout is given in Table 56;In the analysis of Taguchi, the values of each experiment are then converted into a signal-to-noise (S/N) ratio, where the term which refers to the required values (mean) is the signal and the values which are not required (Standard deviation) are represented as the noise for the output characteristics. When analyzing S/N ratios, the quality characteristics are proposed by Taguchi as followsWhen the goal of the experimentation is to maximize the response, selecting “larger is better” quality characteristic is the right choice (Eq. ). HoweveIn the present work, the objective is to maximize the BS, therefore, “larger is better” quality characteristic is selected.59. The dimensions of the standard test specimen are illustrated in Fig. A series of pin-bearing ASTM D5961 tests were conducted on both molded-in and drilled specimens with different fiber contents using a universal testing machine (Testometric 200 kN) at room temperature. Standard test specimens were used to obtain bearing failure mode rather than net tension or shear-out modes that had lower loads associated with catastrophic fracture as recommended by previous studiesInjection-molded fiber-reinforced PP composites of different fiber feedstock lengths (FFSL) of 12 and 24 mm were considered for the analysis. In injection molded parts, the number average fiber length ” and “short fiber/Polypropylene (SFPP)”, respectively.It has been observed from Fig. Figure 25 where the BS of leaf spring made from GFR/PP was higher than that made of un-reinforced PP. Also, as the fiber length increased BS increased. Moreover, Asi66 showed that BS of GFRE firstly increased as linear densities of woven fabric increased (which is an indication of the increase in fiber content) and then decreased with an extra increase in woven fabric linear densities as a result of elevated void content and crimp levels of the obtained composite.It can also be noted from Fig. 60. Where Subramanian et al.24 and Kumar et al.60 found that the strength of composite increases as the mean fiber length increases. Kumar et al.60 noticed that the strength of composite depends mostly on the fiber aspect ratio (or fiber length) more than fiber content, and the reduced strength of the composite caused by decreased mean fiber length almost offsets the increased composite strength caused by higher fiber content.The variety in the percentage of improvement for the BS from L00 to L3012 and L3024 which is three times higher in L3012 (LFPP) than L3024 (SFPP) may be related to the difference in average fiber length (aspect ratio) between them, as found in previous studiesFigure The experimental results of measured BS, the corresponding values of S/N ratios, and experiment code for each trial are shown in Table Tables ANOVA general linear model along with One-way ANOVA was obtained to describe the response of each factor where equal variances for the analysis were assumed. Results of the ANOVA general linear model and one-way ANOVA are summarized in Tables Figure 30 showed that textile-reinforced thermoplastics molded-in holes were able to withstand greater loads compared to the drilled configuration.The bearing test results of Hufenbach et al.20. Bearing failure, which is characterized by a progressive decrease in applied load, is considered the ideal failure mode67. the failure damage of fiber-reinforced material might be attributed to the matrix cracking, fiber fracture, fiber-matrix interfacial debonding, and their combinations68. In this section, the failure mode of bolted joint composites was evaluated by observing the failure surface. Figure Experimentally, the mechanically fastened joints fail under four basic mechanisms; net tension, shear out, cleavage failure, and bearing failure. The net tension, shear out, and cleavage failure modes are not desirable due to the catastrophic nature of final failureThe SEM micrographs of the fracture zone of L1012 and L3012 specimens are shown in Fig. Figure The BS of specimens injected with longer FFSL was found to have a lower BS than shorter ones due to the observed decrease in weight average fiber length in the produced specimen after the injection molding process. The observed decrease in BS starts from 2.85% at 10 wt% up to 5.95% at 30 wt% GFR/PP.For specimens with molded-in holes, for both LFPP and SFPP, BS increases as the fiber weight fraction increases. For LFPP, an improvement of 9% for L3012 specimens above L00 is obtained. While for SFPP, BS increases by only 3% from L00 specimen to L3024 one.For specimens with drilled holes, results obtained from ANOVA and Taguchi analysis indicated that the effects of the machining conditions and weight fraction on BS were different between LFPP and SFPP specimens; for LFPP, the most significant factor was the weight fraction while the drilling conditions (speed and feed) were found to be less significant. However, for SFPP spindle speed was found to be the most significant factor, followed by feed, while the weight fraction has the least effect.The increase in weight fraction leads to an increase in BS for both molded-in and machined hole specimens.BS of the molded-in holes is slightly better than those of machined holes for all used weight fractions and fiber lengths; for LFPP, the average increase in BS for specimens with molded-in holes is about 1% above drilled holes specimens. Whereas for SFPP, the increase in BS for specimens with molded-in holes ranges from 0.8% for neat PP to 2.6% for 30 wt% GFR/PP over drilled holes specimens.Morphology analysis for fractured specimens indicated that; for molded-in hole specimens, plain PP specimens failed under pure bearing failure mode. While GFR/PP specimens failed under bearing and net tension mixed-mode failure. For machined hole specimens, all specimens failed under bearing and net tension mixed-mode failure, except for 30 wt% GFR/PP specimens that failed under net tension failure mode only.An experimental and statistical analysis for BS associated with GFR/PP composites manufactured by injection molding technique with either molded-in or drilled holes at various drilling conditions are presented in this study. The obtained results may be summarized as follow;


A novel haptic grasper that renders touch sensations to the user in 3-DoF (degrees of freedom), namely linear, rotary, and grasping motions, is presented. The touch sensations of the grasper include the combination of kinesthetic and tactile modalities such as stiffness, texture, and shape. The device is equipped with two swappable modular segments that provide stiffness and shape sensations. To increase the haptic fidelity, the textural surfaces that surround the outer surface of the segments are equipped with vibro-actuators underneath them. These vibro-actuators contribute to increasing the number of perceivable textures by varying amplitude, frequency, duration, and envelope of vibrations. The proposed device is characterized in terms of stiffness, shape and texture rendering capabilities. The experimental results validate the effectiveness of the developed haptic grasper in virtual/remote interactions. Also, the user studies and statistical analysis demonstrate that the users could perceive the high-fidelity haptic feedback with the unified sensations of kinesthetic and tactile cues. Human-machine interfaces (HMIs) provide intuitive graphical and manipulation capabilities that assist the user in interacting with machines . The conventional HMIs, such as a joystick, keyboard, smartphones, etc., have been replaced by advanced interfaces such as virtual reality (VR) and augmented reality (AR) haptic devices that render compelling and natural sensations. Haptic devices play an essential role in immersing the user in teleoperation and virtual/augmented environments by providing force/touch information. In recent years, these devices had significant attention and have been actively pursued by many research groups worldwide. The bifacial feature of these interfaces guarantees safe/precise sensing and manipulation, unlike the existing unidirectional interfaces that are limited to visual, vibratory, or auditory feedback. Additionally, introducing haptic interfaces into the human-machine systems elevates the interactions to higher dimensions by conveying physical features through kinesthetic and tactile stimuli . KinesthHaptic interfaces are categorized into grounded devices (tool-based and skeleton-frame) and ungrounded devices such as exoskeleton or wearable devices . Mid-ranAdditionally, the workspace, number of rendered textures, and resolution for these devices are limited. Nonetheless, these interfaces may not provide faithful haptic sensations because of the lack of a proper combination of haptic stimuli and grasping motion. In , it is dIn this paper, we present the design of a graspable haptic interface that provides unified kinesthetic and tactile feedback by rendering the stiffness, texture, and shape modalities in 3-DoF. The goal here is to enhance transparency while interacting with diverse environments. The proposed device includes perception/grasping abilities through multi-contact sensations and has a modular configuration consisting of replaceable modules for providing various sensations. The device also uses a novel flexure-based backlash-compensated mechanism for power transmission to improve haptic fidelity. One of the critical contributions is in emulating the textural feedback by using an arrangement of passive textures backed by vibrotactile actuators. Other contributions are in the grasper’s design with zero backlash, low friction, low inertia, high force bandwidth, and high back drivability.The haptic device has been designed to provide 3-DoF motion with unified kinesthetic and tactile feedback by rendering the stiffness, texture, and shape modalities. The goal of developing this haptic grasper is to enhance transparency while interacting with diverse environments. The grasping system allows users to interact with a virtual environment using their fingers. This system comprises a grasper with texture rendering modules. The vibro-actuators placed beneath the texture module provide the perception of textures by varying the vibration characteristics. The grasper can move in 3-DoF  provided by the motion mechanism, actuated using three motors (DC Maxon motors: RE-30). Each of the motors is controlled using Maxon EPOS 4 50/5 CAN controller. The design details of these modules are explained in the following sections.x-axis), and rotary motion (about the x-axis), as shown in y-axis. These segments are divided into multiple sections, and textures/shapes of various features are attached to these sections through the texture-loading arms, as shown in The grasping system consists of a pair of passive graspers that allow the user to sense and explore the virtual/remote environment using the fingers in 3-DoF, namely the grasping motion , linear motion  that move along the Gear-driven transmission, compared to cable transmission, offers high stiffness but is prone to backlash. An anti-backlash mechanism, typically used in literature, consists of two drive gears mounted co-axially to a common shaft to remove circumferential backlash. One of the gears is rigidly mounted to the drive shaft, while the other is connected through a pair of springs and is floating. The springs are preloaded, and during mounting, the floating gear negates any backlash due to the springs’ torque. Since one of the gears is floating and the spring behaves like a serial elastic element, the system exhibits limited stiffness in one of the directions of gear motion. This stiffness limitation can be addressed by locking both gears. We propose a flexure-based backlash compensated gear drive, as shown in A Finite Element Analysis (FEA) on the flexure has been done to estimate bending stresses, and the results are shown in A separate motor controls the grasping stiffness of the device. A 4-bar slider-crank mechanism, as shown in There are vibro-actuators  integrated into the modular segments to increase the textural sensations, thus recreating different variants of the attached textures. These actuators are mounted between the texture loading arms and modular segments. For optimal performance, a preload of around 7 N is applied (as per the manufacturer) to compress the actuators using the texture loading arm, as shown in An I2C communication-based haptic driver  controls the actuator’s vibrational characteristics. It is connected to an Arduino Uno controller, through which diverse waveforms are generated by varying amplitude, frequency, duration, and envelope of the vibrations. The waveform’s maximum frequency and quick response time of 500 Hz and 2 ms, respectively, enables the actuator to suit various haptics applications . ComplexFor better understanding of the working of the proposed haptic grasper some more figures are provided in the Experiments have been performed to determine the device characteristics and evaluate the haptic grasper’s performance for transparency and quality of rendering.To analyze the transparency in the haptic rendering of the device in 2-DoF (rotary and linear motion), the proposed flexure-based backlash compensated drives were considered. The input and output angles of the gear drive and rack and pinion drive were recorded to study the backlash of the device in 2-DoF. The gears attached to motors (M1 and M3) were given a complete rotation in the clockwise and counter-clockwise directions. The corresponding movement of the ring gear and rack and pinion was measured to compute the backlash. The angular rotation of M1 and M3 were measured using the motor’s integrated encoder. Similarly, the rotary motion of the ring gear and linear motion of the rack and pinion drive was measured using a calibrated camera. The camera data is processed through the Lucas-Kanade point tracker algorithm that utilizes the dominant points of the grasper and calculates the position/velocity from each video sequence frame. The hysteresis exhibited by the gear train for the rotary motion and the rack and pinion drive for linear motion of grasper assembly was computed with and without backlash compensation mechanism, as shown in To analyze the force rendering capability of the device, three workpieces of various stiffness were fabricated using silicone material . The length and radius of the cylindrical workpieces were 3 and 6 cm, respectively, as shown in The goal of the experiment was to compare the reference profiles of the three samples with the profiles rendered by the proposed grasper. Let us assume that the reference and actual nonlinear stiffness to be y-axis), the two modular segments move in and out, providing the global shape profile (bumps and holes). The corresponding grasper’s motion is externally measured using a camera capture system. The rendered trajectory compared with the reference trajectory is shown in To analyze the shape rendering capability of the device, a reference sinusoidal is provided, and the tracking performance of the end-effector (grasper) is assessed. When the user moves their fingers in the grasping direction . One side of the actuator is attached to a fixed plate, and the other side is loaded with 20 g with a thin adhesive tape. The accelerometer is affixed above the load, and the vibration intensity of the movable mass is measured. The input voltage is varied from 0 to 120 V in four different patterns, and the corresponding accelerations are measured. The voltage is provided in terms of variations in the envelope, amplitude, frequency, duration, and the combination of all parameters . In Summary, the parameters affecting the transparency, such as backlash, friction, cogging effects and lack of realistic tactile feedback, have been addressed to provide transparent haptic sensations. A backlash compensation mechanism is proposed to eliminate backlash, and great care has been taken while designing the device to eliminate other effects like friction and cogging by choosing an involute profile for gear teeth. Also, the minimum no. of teeth for the pinion gear of the motors is kept above 17 to prevent tooth interference. For realistic tactile feedback, physical textures have been attached. The number of realizable textures are increased by using vibro-actuators underneath those textures.Three experiments were conducted to evaluate the participants’ perception of haptic sensations such as stiffness, shape, and texture rendered by the grasper. In addition to investigating the sensation discriminating abilities of the haptic grasper, these experiments were used to verify the efficacy of generating unified kinesthetic and tactile feedback. Each of the experiments was performed six times. The experimental setup shown in Force rendering) with the same length (3 cm) and radius (6 cm) but having different stiffness were chosen for analysis. The participants were asked to feel the stiffness profiles by probing the reference specimens along the y-axis using their index and thumb fingers and were sequenced based on the stiffness. Then they were allowed to interact with the haptic grasper similar to the specimen. The haptic grasper rendered three stiffness stimuli in the first block without any textures attached to the modular segment. In the second block, the textural surface similar to silicone specimens was affixed to the texture loading arm, and the grasper rendered the three stimuli (the methodology for generating stiffness through the device was explained in the previous section). The specimens and haptic grasper stimuli were given randomly. After each iteration, the participants reported the matching specimen corresponding to the stiffness stimuli rendered through the haptic device. These two blocks of the experiment illustrate the device’s stiffness rendering capability and the influence of texture on the stiffness modality.In this experiment, two test blocks were considered: stiffness discrimination with and without texture (tactile feedback). Three cylindrical-shaped silicone specimens  and radius (6 cm) are chosen for analysis. Then, each specimen was moulded to form either a bump/hole at the centre with a width of 2 cm. The bump/hole was uniformly placed on the surface. During the experiment, participants were asked to feel the reference shape profiles of the three silicone samples by traversing forward and backwards the surface using their index and thumb fingers. Then they were allowed to experience the stimuli rendered by the haptic grasper by traversing it. When the user interacts with the grasper, the segment rotates and moves laterally about its midpoint. This motion depends on the position of the contact of the fingers with the haptic grasper. The specimens and haptic grasper stimuli were given randomly. After each trial, the participants reported matching specimens corresponding to the shape (bump/hole) stimuli rendered through the haptic device.The confusion matrix that describes the rendered versus actual shape is shown in Force rendering were chosen for analysis. Each signal represents one property of the texture. The change in vibrational characteristics, namely amplitude, frequency, envelope, and duration, produce various surfaces such as gradual bumps/holes (VC1), sudden bumps/holes (VC2), smooth/rough surface (VC3), and length of the random texture, respectively. The participants were asked to feel these reference textural sensations using the index and thumb fingers. Sandpapers of different grits (roughness) were attached as physical textures to the texture loading arm. The sandpapers of grit sizes 40, 80, 120, and 240 with a thickness of 1 mm were utilized for analysis. The sandpapers’ dynamic attributes  are determined using the vibrational sensor for various inputs. So, to recreate reference surfaces, the properties of the attached sandpapers are varied through vibro-actuators by varying voltage inputs. In the first block, the participant was provided with a reference physical texture and the texture rendered by the haptic grasper without probing along the y-axis. In the second block, the participant was allowed to probe the grasper along the y-axis to feel both stiffness and texture. The stimulations of these textures were provided randomly. The signal patterns were repeated based on the participant requirement with a time delay of 300 ms to realize the sensation properly. These two blocks illustrate the device’s texture rendering capability and the influence of stiffness on the texture modality.In this experiment, two test blocks, namely texture discrimination with and without stiffness, were considered. Four different signals illustrated in The confusion matrices that describe the rendered versus actual textural surfaces without and with stiffness are shown in In this section, the outcomes related to psychophysical experiments are discussed in detail. In the stiffness, shape, and texture discrimination tasks, the participants could easily discriminate between different stiffness (nonlinear), shape and texture profiles and match the reference stimulus provided by the haptic grasper.To understand the influence of stiffness modality on texture modality and vice-versa, the average cognitive accuracy of both experiments is normalized and considered for analysis. In the stiffness discrimination experiment, for the applied user’s force, the deformation of the haptic grasper is more in the case of the E20 specimen because of its low stiffness, and therefore, the users could easily identify this specimen. Based on the stiffness constant, the deformation of the E30 specimen is higher than the E50 specimen for the same applied force. The participants should have easily differentiated between E30 and E50 specimens. However, the users became confused between these two specimens because of their low deformation compared to the E20 specimen. The relative accuracy of the E50 specimen is higher than the E30 specimen since it has high stiffness. From the experimental analysis, it is understood that the user could accurately recognise the softest (E20) specimen, followed by the hardest (E50) specimen and then the E30 specimen. Although the accuracy of identifying specimens has increased by adding the texture modality, the order remains the same regardless of adding other modalities. In the texture discrimination experiment, the user could easily identify the length of random texture (VC4) because of the variations in both amplitude and frequency compared to other profiles. The sudden change of four levels of variations in amplitude (VC2) and frequency (VC3) could also be recognised by the users next to VC4. The gradual amplitude variations (VC1) could not be recognised because the user could not identify the slight change in amplitude and had been confused with other profiles. However, when the stiffness modality is added to the texture, the variations in amplitude (VC2) are sharply felt by the user with the applied force, thus taking the superior position compared to VC3. The other order remains the same with added stiffness modality.The metrics of interest in these experiments were relative cognitive accuracy and the standard deviation. The collected data of the two groups passed both the Shapiro-Wilk normality test and Levene’s variance homogeneity test. The stiffness/texture discrimination experiments show the normalized mean accuracy of stiffness with/without textures (Case A) and rendering of texture with/without stiffness (Case B) along with their error bars is shown in modality , the proAdditionally, the proposed haptic grasper workspace is limited, as mentioned in the device specifications , becauseIn comparison with the state of literature , the perTo demonstrate the virtual reality (VR) interaction with various environments, two VR scenarios are custom-developed in Unity 3D to highlight the attributes of the haptic grasper. The 3-DoF of the haptic device is synchronized with LabVIEW software, and these signals are sent to the virtual environments made in Unity 3D through the User Datagram Protocol (UDP) channel. Ten participants were immersed in these experiments to evaluate the naturalness of these interactions, holding the device with their fingers. The first application emphasizes various abilities of the device, such as the degrees of freedom, stiffness, shape, and texture modalities. In this scene, a cylindrical object is chosen with two different textures (green and violet), as shown in Force rendering. The shape information of the muscle is experienced by the user’s longitudinal and rotary movement of the haptic grasper, which is explained in Shape rendering. The shape and stiffness of the muscle are rendered simultaneously by utilizing the coordinated movements of all the three DoF of the device. The users experiencing these muscle features could differentiate between a healthy and an affected one. The users could also identify the precise position of the affected muscle area and the differentiating factor with respect to the healthy muscle in terms of change in shape or stiffness. Participants’ responses were recorded using a questionnaire based on a Likert seven-point scale  to assess the user’s experience of different haptic sensations in virtual environments. The questions were presented to the participants in random order. The mean and standard deviation of the scores was calculated based on the user’s rating, and the same has been reported in The second VR scenario is related to the application of telesurgery, exploring various features of a virtual muscle. In this demo, the virtual muscle characteristics (haptic feedback) are rendered to the participants users by mapping with the device workspace (as mentioned in The proposed device finds its use in many human-machine interface applications such as telesurgical systems, training medical apprentices, space and underwater exploration, rehabilitation, industrial operations, and entertainment . For exaAdditionally, the modularity of the device extends its usage for a variety of remote/virtual environments. The drive motors are mounted directly in the device to keep design complexity minimum for the initial prototype. In future versions, the motors can be placed remotely by using Bowden cable transmission to enhance the workspace and reduce the device’s weight.This paper presents a graspable haptic interface that enables users to grasp and interact with different virtual/remote environments with haptic modalities, such as stiffness, shape, and texture. Both kinesthetic and tactile feedback are presented simultaneously in grasping, linear, and rotary DoF. The system characteristics and performance of the device have been elaborated. The psychophysical experiments and questionnaire using Likert seven-point scale results demonstrate that the haptic grasper could provide the natural feel of interacting with various virtual objects/environments. Furthermore, the analysis relating to the performance of the discrimination tasks for stiffness, shape, and textural feedback has been studied using statistical analysis. It is also found that textural feedback plays a prominent role in rendering the stiffness. Finally, applications of the haptic grasper have been reported with a detailed explanation of the use of the device for telesurgical systems. Future works comprise miniaturization and extending the haptic grasper to a wearable device, thus enhancing the workspace and applications.


Compared to national evaluations, international collaboration projects further improve accuracies of estimated breeding values (EBV) by building larger reference populations or performing a joint evaluation using data (or proxy of them) from different countries. Genomic selection is increasingly adopted in beef cattle, but, to date, the benefits of including genomic information in international evaluations have not been explored. Our objective was to develop an international beef cattle single-step genomic evaluation and investigate its impact on the accuracy and bias of genomic evaluations compared to current pedigree-based evaluations.INT) and an international pedigree-based BLUP evaluation (PBLUPINT). Two national scenarios were implemented for pedigree and genomic evaluations using only nationally submitted phenotypes and genotypes. Accuracies, level and dispersion bias of EBV of animals born from 2014 onwards, and increases in population accuracies were estimated using the linear regression method.Weaning weight records were available for 331,593 animals from seven European countries. The pedigree included 519,740 animals. After imputation and quality control, 17,607 genotypes at a density of 57,899 single nucleotide polymorphisms (SNPs) from four countries were available. We implemented two international scenarios where countries were modelled as different correlated traits: an international genomic single-step SNP best linear unbiased prediction (SNPBLUP) evaluation offspring across two countries were genotyped. ssSNPBLUPInternational single-step SNPBLUP evaluations are feasible and lead to higher population accuracies for both large and small countries compared to current international pedigree-based evaluations and national evaluations. These results are likely related to the larger multi-country reference population and the inclusion of phenotypes from relatives recorded in other countries via single-step international evaluations. The proposed international single-step approach can be applied to other traits and breeds.The online version contains supplementary material available at 10.1186/s12711-022-00748-0. In livestock species, genomic selection  has becoIn cattle, the aim of international collaborations projects is to pull together genomic data from different countries and build large reference populations within the same breed . These pGenomic selection has also been increasingly adopted in beef cattle national evaluations –24, howeWhen properly parametrized, it is expected that the optimal approach for international genomic evaluations would be to implement a single-step evaluation because it allows combining phenotypic, genomic and pedigree national information simultaneously , using rHereafter, we first describe the available data and its preparations steps, followed by the implemented scenarios and a description of the international models used. Finally, we describe the assessment of connections among countries and the validation methodology implemented.In total, 333,333 Limousin male and female age-adjusted weaning weight (AWW) phenotypes were available. Phenotypes were available from five Limousin populations, representing seven European countries joining the 2020 January Interbeef evaluation. These countries were: Czech Republic (CZE), Denmark, Finland and Sweden , Ireland (IRL), Germany (DEU), and Switzerland (CHE). Weaning weight was age-adjusted to 210 days in CZE and to 200 days in the remaining countries. For further details on data recording and adjustment factors at the national level see Additional file The pedigree was extracted from the Interbeef international pedigree database and the following quality controls were performed. The pedigree was checked for absence of pedigree loops , duplicates, and conflicts between the sex reported in the international identification number and its sex as a parent . Finally, using the RelaX2 software v1.73 , the cheGenotypes were available for 17,733 animals from four countries: CZE, DEU, IRL, and CHE. Genotypes were available from single nucleotide polymorphism (SNP) panels with different SNP densities: 467 DEU animals at 41,913 SNPs (42K), 11,354 IRL animals at 52,690 SNPs (52K), 1004 CZE animals at 53,218 SNPs (53K), 278 DEU animals at 54,609 SNPs (55K), and 648 CZE and 3982 CHE animals at 139,480 SNPs (139K). SNPs were coded as 0 and 2 for the two homozygotes, and as 1 for the heterozygote. Genotypes originating from different sources were merged using the unambiguous A/B Illumina allele coding [Genotypes sent by various countries were imputed to a selected panel of SNPs as described in the following sections.Bos taurus UMD 3.1 bovine genome assembly [SNPs in common with the selected panel were retained from each country genotype; the remaining SNPs were discarded. Table SNPs with too many Mendelian conflicts were removed. A SNP was removed from the selected panel if the number of parent–offspring genotype conflicts exceeded 1% of the parent–offspring pairs that both have their genotype called for this SNP. In total, 1411 SNPs were removed.Detection of parent–offspring conflicts. A parent–offspring conflict was detected when the number of conflicting autosomal SNPs between the parent–offspring pair exceeded 1% of the number of SNPs shared between the SNP panel used for the parent and the offspring  were used for imputation.Only autosomal SNPs with a known name and chromosome position for the assembly  were retp-value for Hardy–Weinberg equilibrium Chi-square test higher than 10–15; (3) SNPs with a minor allele frequency higher than 0.01; and (4) call rates per animal across SNPs ≥ 90%. SNPs and genotypes that did not match these criteria were removed and thus 17,688 genotypes and 57,899 SNPs remained. The percentage of autosomal SNPs retained after quality control relative to the original panels were 89%, 94%, 77%, 74%, and 40%, for the 42K, 52K, 53K, 55K, and 139K panel, respectively. In addition, genotypes with less than 87.5% pedigree-based breed composition for the Limousin breed were removed (32 genotypes excluded), and genotypes with pedigree incompatibilities  evaluation (as described below) using all available phenotypes. This scenario represents the current Interbeef international evaluations.Scenario PBLUPINT: international single-step SNPBLUP evaluation (as described below) using all available phenotypes and genotypes.Scenario ssSNPBLUPTo investigate the benefits of including genomic information in international evaluations compared to the current international pedigree-based evaluation, we implemented the following two scenarios, hereafter referred to as “international scenarios”.In both international scenarios, the complete international pedigree was used.NAT: national pedigree-based BLUP evaluation, performed separately for each country using only national submitted phenotypes  , which amentclass2pt{minim–4). The final across-country genetic correlation matrix The genetic co-variance matrix with additive direct and maternal genetic effects  approach as proposed by Liu et al.  and lateThe compatibility between pedigree and genomic information was guaranteed by fitting two he model . Such cohe model , 47. In  follows . First, o et al.  and Hsu o et al. , the proINT evaluation.In international evaluations, genetic connections among countries are mainly provided by common bulls (CB), i.e. sires that have recorded offspring in two or more countries. Therefore, we quantified the number of CB and common maternal grand-sires . Furthermore, we quantified the number of sires and dams with recorded offspring in each national pedigree. Then, for all these groups of animals, we also quantified whether a genotype was provided by the same country or provided by other countries. This shows the potential increases in genetic connectedness among countries over national evaluations and pedigree-based international evaluation due to the inclusion of genotypes provided by other countries in a ssSNPBLUPWe used the linear regression (LR) method  to evaluLevel bias  and 0.25 (ranging from 0.23 for CZE and DEU to 0.29 for CHE), for direct and maternal EBV, respectively.Bias and accuracy of EBV were calculated comparing partial and whole EBV of each scenario. Overall, ssSNPBLUPBV Table . For dirINT performed better than PBLUPNAT based on level bias, dispersion bias, and accuracy. Indeed, for direct EBV, ssSNPBLUPINT showed less level bias and less over-dispersion  compared to PBLUPNAT, with values of INT showed similar level bias compared to PBLUPNAT: difference in INT compared to PBLUPNAT: average difference in NAT to small over-dispersion of ssSNPBLUPINT. Finally, in all countries the accuracy of partial EBV was greater in ssSNPBLUPINT than in PBLUPNAT: on average across countries, the difference in Overall, ssSNPBLUPL) Table . For matINT showed similar level bias and dispersion bias for both direct and maternal EBV compared to ssSNPBLUPNAT, but ssSNPBLUPINT did have a higher accuracy  Table . For matINT scenario  for these animals when moving from any other scenarios to ssSNPBLUPINT  to 15% (CZE). Differences for DEU and CHE could be related to selective genotyping. Differences in genetic trends between pedigree-based and single-step evaluations were already present for national scenarios and reduced for international scenarios (results not shown). Overall, the results of this study suggest that level and dispersion bias of national evaluations will remain similar or slightly decrease with international single-step genomic evaluations.To our knowledge, this is the first published study that investigates bias in Interbeef evaluations. We evaluated whether moving towards genomic international models may introduce any level and dispersion bias compared to either international pedigree-based evaluation or national evaluations. Overall, ssSNPBLUPmentclass2pt{minimt et al.   for direct EBV and 0.19 for maternal EBV (ranging from 0.17 for CZE to 0.22 for CHE). In ssSNPBLUPNAT, So far, only few national studies reported LR estimates in beef cattle, in particular for weaning weight. Overall, we observed improvements in s et al.  as well s et al.  reportedg et al.  and Campg et al.  reportedg et al. .INT and ssSNPBLUPINT scenarios . Si. SiNAT rps  and 4 GB of RAM, and an appropriate two-level PCG method [The increasing genotyping trend observed at the national level Fig.  implies tractive , 73. In G method .The proposed international single-step approach requires sharing genotypes and phenotypes at the international level, which is subject to some limitations. For instance, in the Genomic MACE Service released by Interbull Centre for the Holstein breed, the international genomic EBV of young bulls are computed from national genomic EBV provided by participating countries  to avoidWe developed an international single-step SNPBLUP genomic evaluation for beef cattle using Limousin weaning weight data and investigated the benefits of using genomic data compared to current pedigree-based evaluations. Combining multi-country genomic data in a single-step approach has the potential to increase existing pedigree-based genetic connectedness among countries via genotyped animals. Single-step international evaluations showed to increase accuracies of EBV compared to current pedigree-based international evaluations for both large and small countries as well as for countries with different amounts of genotypes at the national level. In this study, the increase in population accuracy when moving from current pedigree-based international evaluations to single-step genomic evaluation was on average across countries 13.7% and 25.8% for direct and maternal EBV, respectively. Moreover, increases in accuracies were observed for non-genotyped animals and countries without genotypes at the national level. Level and dispersion bias of international single-step genomic evaluations were similar or slightly reduced compared to current pedigree-based international and national (genomic) evaluations. The proposed international single-step approach can be applied to other traits and breeds allowing countries to improve the accuracies of their genetic evaluations.Additional file 1: Table S1. Number of phenotypes (N), minimum, mean, maximum, and phenotypic standard deviation , genetic variances  and genetic correlations  within and across countries. Table S4. National genetic, environmental and residual (co)variances. Table S5. Level bias  and Common Maternal Grand-Sires (CMGS). Table S8. Level bias  and genomic-based (y-axis) relationships between genotyped animals. The red dots indicate the relationships of the 41 genotypes removed due to pedigree incompatibilities. Figure S2. Differences in genetic trends between ssSNPBLUPINT and PBLUPINT per country for sires with at least 10 recorded offspring in the country (only birth years with at least 5 sires are included).Additional file 4: Figure S3. Direct and maternal EBV realized Mendelian sampling (RMS) trends in each countrya expressed in genetic standard deviation (GSD) for genotyped and non-genotyped animalsb computed with pedigree-based BLUP international (PBLUPINT) and single-step SNP-BLUP international (ssSNPBLUPINT) models. aCZE Czech Republic, DFS Denmark, Finland and Sweden, IRL Ireland, DEU Germany, CHE Switzerland. bGenotyped animals: animals with genotype that appear in the pseudo-national pedigree (with or without phenotype in the country). Non-genotyped animals: animals that appear in the pseudo-national pedigree without genotype and with phenotype in the country.


Health problems associated with excess calories, such as diabetes and obesity, have become serious public issues worldwide. Innovative methods are needed to reduce food caloric impact without negatively affecting sensory properties. The interaction between starch and phenolic compounds has presented a positive impact on health and has been applied to various aspects of food. In particular, an interaction between polyphenols and starch is widely found in food systems and may endow foods with several unique properties and functional effects. This review summarizes knowledge of the interaction between polyphenols and starch accumulated over the past decade. It discusses changes in the physicochemical properties, in vitro digestibility, prebiotic properties, and antioxidant activity of the starch–polyphenol complex. It also reviews innovative methods of obtaining the complexes and their applications in the food industry. For a brief description, phenolic compounds interact with starch through covalent or non-covalent bonds. The smoothness of starch granules disappears after complexation, while the crystalline structure either remains unchanged or forms a new structure and/or V-type complex. Polyphenols influence starch swelling power, solubility, pasting, and thermal properties; however, research remains limited regarding their effects on oil absorption and freeze–thaw stability. The interaction between starch and polyphenolic compounds could promote health and nutritional value by reducing starch digestion rate and enhancing bioavailability; as such, this review might provide a theoretical basis for the development of novel functional foods for the prevention and control of hyperglycemia. Further establishing a comprehensive understanding of starch–polyphenol complexes could improve their application in the food industry. Over the past century, consumer perceptions of the link between food and health have been changing. Modern consumers need not only high-quality, delicious products but also ones that can provide many health benefits. Bioactive food compounds are one of four potential sectors of food innovation in the era of the COVID-19 crisis and the influence of changing consumer behaviors and the agri-food industry ,3. AccorStarchy food products are often associated with chronic diseases such as obesity, diabetes, blood pressure, and heart disease . ConsequModulating starch with phenolic compounds also changes the functional properties of starch, including its physicochemical properties, pasting properties, thermal properties, and digestibility ,17. In pThis review provides ten-year recent research information on the changes in physicochemical properties, functional properties, and health benefits associated with diverse types of starch–polyphenol complexes, along with information on the innovative advanced methods being used to produce them. Digital searches of the literature were conducted utilizing a variety of databases, including Google Scholar and PubMed, two popular online research databases, and websites of selected journal publishers such as MDPI, ScienceDirect, and Springer. Some of the common search terms were “starch and polyphenol interaction”, “starch and polyphenol complex,” and “starch and phenolics compounds”. The collecting and summarizing process followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) principles . A total6H10O5)n. The most basic type of starch is the linear polymer amylose, while amylopectin is its branched counterpart [Starch is a polysaccharide made up of 1,4-linked glucose monomers and hence has a chemical formula of  into slowly digestible starch (SDS) and resistant starch (RS) while also taking advantage of the functional biological properties of phenolics to improve the immune system. Other properties of starch that could be altered include the aggregate structure, swelling and solubility, gelatinization, crystallization, and pasting, which affect further processing. The properties reported to be altered in starch–polyphenol complexes are listed in As a semi-crystalline biological polymer, starch displays birefringence under polarized light. Starch granules are ovoid, spherical, or irregular in shape and range in size from 1 to 175 µm, depending on the plant . To obseSignificant changes can be observed in many cereal starch granules after complexation under different conditions or with endogenous polyphenols, such as in recent research on maize , rice 4, buckwheWhile the above findings are interesting, there is yet only limited research on particle size, nano-level granule changes, and differences in granule changes among starch modified via different processing methods. Thus, more research should be conducted on nano-level morphology under various conditions and on the effects of starch granule properties on the formation of complexes so as to better understand the effects of complexation.13C CP/MAS NMR) [The structure of starch determines its physicochemical and functional properties. Currently, techniques commonly applied to identify the interaction of phenolic compounds and starch include diffraction scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy ,46. AddiMAS NMR) , and higMAS NMR) ,48,49.Polyphenols interact with starch through covalent or non-covalent bonds depending on the type of starch and phenolic compound in question. The degree of complexation can be evaluated based on the differential absorbance percentages of native and complexed starch after binding with iodine . The comPhysically, polyphenols tend to form compounds with the amorphous hydrophobic area of single helices of amylose. This interaction results in an increased RS level or the formation of a new type of enzyme-resistant starch. Conversely, increasing amylose content in maize starch is negatively correlated with the complexation index between starch and caffeic acid . While aIn recent years, X-ray diffraction has commonly been used to determine starch complexes’ crystalline type and crystallinity. The starch crystal structure is classified as A-type, B-type, C-type (a mixture of A-type and B-type), or V-type based on the X-ray diffraction peaks . Recent For instance, maize starch complexed with longan seed polyphenols exhibited three new XRD peaks at 2θ = 7.5°, 12.7°, and 20.1°  , while cGenerally, the crystal structure of the complexed starch is mainly influenced by its amylose content and the type of polyphenol it is complexed with . Researc−1, respectively. In addition, the short-range organized molecular structure of starch, including the presence of single and double helical structures, has been characterized using 13C CP/MAS NMR. This method can reveal how the starch interacts with other ingredients as well as small molecules  during processing. The number of C1 peaks can be utilized to identify crystal type, while the intensity in the C1 region indicates changes in a starch’s double-helical structure. The amorphous nature of amylose is evident in the C2, C3, and C5 areas (70–79 ppm), which are affected by the amylopectin cluster structure and inversely correlated with the vibrational peak’s intensity [The study of short-range molecular structural changes in starch double helices has made extensive use of IR spectroscopy, as crystalline organized and amorphous structures on the starch surface can be detected by the IR absorbance at 1045 and 1022 cmntensity ,61. The The starch molecules that interact with phenolic compounds are amylose and possibly-linear fragments of amylopectin . When stThe textural, sensory, and stability characteristics of starch-based food products are influenced by the functional characteristics of the starch in question, such as its capacity to swell, dissolve, and absorb oil. Under specific circumstances, starch can bind water molecules by forming hydrogen bonds between adjacent hydroxyl groups. The ability of starch to retain water at particular temperatures is measured as its swelling power . AmyloseAn instrument commonly used to investigate changes in starch pasting properties is the Rapid Visco Analyzer (RVA) . From thA recent study introduced the breakdown value, which represents the degree of amylose leaching, and the setback value, which represents amylose and amylopectin retrogradation . Post-copeak–Tonset) and melting enthalpy [The thermal characteristics of starch complexes are drastically altered upon the addition of polyphenols, but the effect differs based on the complexation conditions. The influence of changes in the crystalline structure of starch on thermal properties is identified by DSC analysis. Several studies have shown that starch onset temperature (To), peak temperature (Tp), and conclusion temperature (Tc) are all decreased after complexation with polyphenols, in particular, the study of Li et al.  on caffeenthalpy . Notablyenthalpy , as amylenthalpy . Kan, Caenthalpy  explaineenthalpy . Changesenthalpy .Freeze–thaw stability, which may be determined as the amount of water that separates from a gel after freezing and thawing, is a crucial measure of starch structure stability . The retStarch digestibility is one of the principal factors impacting consumer health, especially in the context of diabetes and obesity. It is related to the glycemic index, which is a measure of blood sugar levels after consuming starchy foods. Studies using in vitro methods have shown that starch modified by complexing with phenolic compounds induces a less-rapid increase in glycemic values. Recent studies and updated information indicate that this process can be expressed through two main mechanisms.Firstly, polyphenols inhibit the amylase enzyme and decrease its activity during starch hydrolysis metabolism . PolypheAs a second mechanism, phenolic compounds can also effectively inhibit the digestion of starch by forming bonds with the starch molecules; this has been demonstrated in previous studies using tea polyphenols, flavonoids, ferulic acid, quercetin, tea extracts, gallic acid, lotus extracts, proanthocyanidins, tannic acid, p-coumaric acid, and sinapic acid ,89,91,92Bifidobacterium and Lactobacillus [Diet has a significant impact on the composition of the gut microbiota, particularly with regard to host-beneficial bacteria such as bacillus . Intestibacillus . Betweenbacillus ,96,97. Sbacillus  but havePolyphenols are naturally occurring, biologically active secondary metabolites of plants present in fruits and vegetables and are receiving increasing attention due to the fact that they possess medicinal effects such as antibacterial, antifungal, and antioxidant properties  and alsoWhen modified with phenolic compounds, the antioxidant properties of starch are increased, and the in vitro digestibility is decreased, as previously indicated. The addition of phenolic compounds to starch may also delay their release, particularly for those of high molecular weight, into the large intestine (in vivo), where they can scavenge free radicals that are responsible for several disorders . NotablyFood matrix composition, including the presence of polyphenols, affects starch digestibility during food processing. In particular, polyphenol compounds have the potential to delay postprandial blood glucose and reduce starch digestion ,93. Non-w/w) to modulate the in vitro digestibility, which resulted in increased resistant starch content and decreased the predicted glycemic index. Analysis by Attenuate Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR) and Small Angle X-ray Scattering (SAXS) revealed that at lower concentrations, gallic acid might act as a molecular chaperone, allowing starch-ordered structures to reassemble and form, while at higher concentrations, the starch hydrogen bonding networks were broken, and the ordered multi-scale structures of starch gel were diminished. Han, Zhang, Zhang, Huang, Jia, Huang, and Liu [Chemical and enzymatic methods have also been used to synthesize phenolic starch esters. For instance, Reddy et al.  reported and Liu  likewiseStarch digestion begins with salivary amylase enzyme in the mouth when chewing and continues in the stomach, after which the remaining undigested starch, called resistant starch, ferments to form short-chain fatty acids (SCFAs). In the human body, SCFAs are produced by probiotic bacteria in the gut system and might protect against colon cancer ,11,108. Recent studies have shown that black rice anthocyanin extract confers a dose-dependent reduction in starch digestibility, and its use in bread alters starch digestibility not only through enzyme inhibition but also changes in food microstructure. As the prevalence of chronic diseases such as diabetes is increasing and becoming increasingly important worldwide, the link between food and health has been and continues to be of interest. Taking advantage of the interaction between starch and polyphenols could not only help to reduce the incidence of some chronic diseases but also promote polyphenol delivery and improve consumer health through their functional effects ,113,114.In addition to regulating starch digestion, polyphenols can also regulate blood glucose levels . RegardiThe application of modified starch products is of increasing interest and popularity in the food industry. Modified starch offers functional properties that meet product requirements and provide several health benefits, and as such, it is commonly applied to many commercial products, including bread, pasta, rice noodles, pasta, cookies, dumplings, steam buns, and more. In recent years, starch modified with polyphenols has also been widely studied and developed for use in starch-based products. In general, adding polyphenol-rich extracts/sources results in reduced product digestibility due to the formation of starch complexes via hydrophobic interactions and hydrogen bonds and reduced amylase enzyme activity, as discussed above. For instance, the fortification of bread with anthocyanins from black rice reduced the digestion rate by approximately 12–20%, depending on the amount of dried extract ,118. A sNotably, fortifying food products with polyphenol sources changes not only dough formation and development but also the physical characteristics of the final product. For instance, caffeic, ferulic, syringic, and gallic acids decrease the mixing time and shearing tolerance of dough , while tStarch retrogradation is another vital factor in determining the quality of food. In polyphenol–starch complexes, the interaction between the hydroxyl groups of the polyphenols and the side chains of the starch molecules may prevent starch from retrograding, slowing the recrystallization process and starch aging . The delTo summarize, polyphenol–starch-based products not only promise to be beneficial for diabetes with their low digestion rates but also to build immune system function through the presence of phenolic compounds. The interaction between the phenolic compounds and starch changes the microstructure of the starch, as discussed above, and changes in the physicochemical properties, digestibility, and retrogradation were also observed when supplementing with polyphenols. However, the relationship between phenolic compounds and starch, as well as the variation relating to processing and storage in the food system, is still to be elucidated . The infThe use of fruits and vegetables and other natural sources rich in antioxidant compounds such as polyphenols, flavonoids, and their derivatives in preventing and supporting the treatment of several diseases has been widely and deeply studied ,129. PolA recent study showed that complexation could also be produced and observed through thermal-assisted treatment; however, some common phenolic compounds, such as anthocyanins, are sensitive to heat processing . On an iSome starch-rich flours contain natural phenolic compounds, such as blue maize flour, which is rich in ferulic and coumaric acids and anthocyanidins (cyanidin and pelargonidin); these also have potential as functional ingredients for the development of potential nutraceutical foods . In partIn summary, the modification of starch with phenolic compounds changes its physicochemical properties, functional properties, and product characteristics based on the types of phenolic compounds and the starch source. In addition to reducing the digestibility and regulating the glycemic index, complexation also provides some beneficial properties owing to the inclusion of functional phenolics. Utilizing polyphenol sources from by-products to improve the functional properties of starchy products could also promote sustainable agricultural production. However, only limited studies are available concerning prebiotic potential, digestibility when applied in food systems, and the effects of processing techniques on the resulting products. Healthy foods are a focus of future food development, and starch–polyphenol complexes have enormous potential for application within the food industry, but more research is still required to make them commercially feasible. Thus, this research area merits more consideration and promotion.


When grouping the dimensional changes by graft particle size  particles, combination of small and medium (>500 μm)/large (>1000 μm) particles, and only medium/large particles), there was a trend for greater resorption associated with smaller particles, but it was not significant; neither in the mesiodistal nor in the vertical dimension . No implant was lost during the observation period. In conclusion, the transcrestal technique for maxillary sinus augmentation documented a high level of predictability. The low clinical morbidity and the contextual dental implant positioning is clinically useful in relation to a significant reduction of the time required for implant restoration, a consistent decrease of the number of surgical phases, and a cost-effectiveness approach for the rehabilitation. The graft resorption pattern in all cases was compatible with persistent implant protection and support.Background. The maxillary sinus lift is a popular and predictable technique associated with implant-supported rehabilitation of the severely atrophic maxilla. The aim of the present retrospective study was to investigate the effectiveness of transcrestal maxillary sinus augmentation and the graft resorption pattern using different heterologous bone substitutes. Methods. A total of 75 sinus-grafting procedures were performed and 89 implants were placed in 66 patients, 24 males and 42 females, with mean age 67.9 ± 10.64 years (range 43–84 years). Nineteen subjects were smokers. The mean follow-up period was 93.33 ± 54.71 months (range 14–240 months). Clinical and radiographical evaluations were performed. Graft height and width were measured at baseline and at the latest follow-up. Results. Mesiodistal and vertical resorption averaged 9.3 ± 20.7% (standard deviation), and 5.04 ± 9.9% of the postoperative size, respectively, considering the graft as the unit. Linear regression analysis showed that graft resorption in both the vertical and the mesiodistal dimension is independent of the follow-up time. Conversely, there was a trend for greater resorption when increasing the postoperative graft size, in both vertical ( Posterior maxillary atrophies represent a critical occurrence in dental implant procedure and a limitation for a fixed rehabilitation of this area ,2. This This retrospective study was conducted in a private dental practice in Conegliano (TV) Italy. The study was in accordance with the Good Clinical Practice guidelines and followed the guidelines of the Declaration of Helsinki. Ethical Board approval was not required, given the observational retrospective nature of the study, which was conducted in a private clinic, under daily clinical practice conditions, following standard protocols. Informed consent for data evaluation and publishing has been obtained from all included subjects.All patients included signed a written consent form before the intervention. The present investigation enrolled patients who required implant rehabilitation of the posterior maxilla and a maxillary sinus augmentation procedure with the transcrestal technique using a heterologous bone substitute as grafting material, and who received follow-up at least 3 months after prosthesis delivery.Surgeries were performed by a single surgeon. Patients were treated from January 2001 until September 2020. The surgery consisted of one-stage implant placement and sinus augmentation via trancrestal technique. All patients received a panoramic radiograph and a Cone Beam Computed Tomography scan before surgery. In all subjects, local anaesthesia was performed with 4% articaine and 1:100,000 epinephrine  before the surgery.An intracrestal incision was made on the medial side and continued to the distal side, and a full-thickness flap was raised to gain access to crestal bone.For the implant site preparation, a lance-shaped drill of the implant kit was used, followed by a 2 mm drill, until reaching the internal cortical of the maxillary sinus. It was important to maintain a sub-preparation of the site in accordance with the drilling protocol  of the implant company always used below the internal cortex of the sinus.The internal sinus cortical was not fractured with the osteotome but rather depleted with internal irrigation with a particular blunt tip capable of gradually consuming the bone without fracturing it. , Italy).Once the cortical layer was removed, the sinus membrane was gently detached, and the augmentation was performed with the addition of particulate bone substitute (from 0.2 cc to 0.5 cc per site).The dental implants were inserted at 30 N/cm to the crestal level and the healing screws, of 3–5 mm height, were directly applied in order to make them monophasic. Vertical U sutures were made, mesial and distal to each implant. Antibiotic prophylaxis with Augmentin 1 g 2 times a day for 6 days and painkillers if needed were prescribed. Sutures were removed 10 days after surgery.Check-up was conducted at 1 month after surgery and radiography after 3 months. At approximately 4–6 months, definitive impressions were taken to complete the cases over the next 2 months.® In the present study, all the biomaterials used for the bone sinus augmentation were produced by Tecnoss® mp3® is a cortico-cancellous porcine bone mix, composed of 90% granulated mix and 10% collagen gel. Two types of granulometry are available for OsteoBiol® mp3®: 600–1000 µm and 1000–2000 µm.OsteoBiol® Putty is a cortico-cancellous porcine bone mix, composed of 80% granulated mix and 20% collagen gel. This material has a plastic consistency due to the presence of collagen gel loaded with 80% micronized bone mix and has a granulometry up to 300 µm.OsteoBiol® Gel 40 is another cortico-cancellous heterologous bone mix. It is made of a collagen matrix (type I and III), obtained using an exclusive Tecnoss® process, loaded to 60% of its volume with micronized porcine bone granules (granulometry up to 300 µm).OsteoBiol® GTO® is a heterologous bone grafting material made of a mix of collagenated cortico-cancellous granules of size ranging from 600 to 1000 µm. OsteoBiol® GTO® is composed of 80% granulated mix of porcine origin and 20% OsteoBiol® TSV Gel.OsteoBiol® Apatos® is a cortico-cancellous porcine bone mix with a granulometry of 600–1000 µm and 1000–2000 µm. The tissue collagen is degraded and physically appears as radiopaque granules of mineral hydroxyapatite.OsteoBiol3(PO4)2, with granulometry of 500–1000 µm, generally used in association with OsteoBiol® Putty or autogenous bone.Bioresorb is a synthetic material composed of ß tricalcium phosphate (Ca)Autologous bone was taken from the drill used to prepare the implant site.All patients underwent the same pre- and post-surgical protocol. Intraoral radiographs taken with the parallel technique were used for the measurements and were analyzed at the time of surgery and at the longest follow-up by a single experienced evaluator.https://it.libreoffice.org/, accessed on 23 January 2021), the evaluator underwent a calibration procedure, consisting in measuring the set distances on a sample of 10 radiographs. The implant length and width were used as reference for calibration. An error was considered acceptable when the maximum difference between consecutive measurements of the same distance was below 5%.Using the Libre Office program (The following distances were measured at insertion (baseline) and at follow up:Graft width : the distance from the most mesial point of contact of the graft with the sinus floor, to the most distal one (at graft level).Mesial and distal extension: the distance from the most mesial/distal point of contact of the graft with the sinus floor to the mesial/distal aspect of the  implant (at graft level).Vertical implant apex-graft: the distance from the central point of the apical end of the implant to the most apical point of the graft, along the implant axis (at implant level).Total vertical bone height: the distance from the bone crest to the most apical point of the graft, along the implant axis (at implant level).Residual bone height at the implant site: height of the sinus floor, expressed as the mean of the values measured at the mesial and distal aspect of each implant (at implant level).For calibration of each image, the known implant length and diameter were used as reference. The change between baseline and follow-up measurement was calculated for each distance.p = 0.05. Descriptive statistics was used to describe the features of the sample, using mean values and standard deviations (SD). The difference between baseline and follow-up values was evaluated using paired Student t-test in case of normal distributions. Normality of the distributions was assessed using the D’Agostino and Pearson’s omnibus normality test. Linear regression analysis between baseline values and changes (both in mm and in percentage), and between changes and follow-up time, was undertaken. One-way analysis of variance (ANOVA) was used to compare graft dimensional changes among the various grafting biomaterials. For this analysis, the biomaterials were aggregated into 3 groups, according to the granule size: <300 μm (only injectable grafts: Putty and Gel 40), combined grafts , >500 μm (grafts not including Putty and Gel 40). The difference between groups was evaluated using the Tukey test. Values of vertical change from adjacent implants in the same patients were averaged. The level of significance was set at p = 0.05.The software Graphpad Prism version 5.1 was used for statistical analyses. The significance was set at Sixty-six patients were enrolled in the present study. Nine of them had a bilateral sinus augmentation, so that a total of 75 sinus grafting procedures were performed. Twenty-four were males and forty-two were females, with a mean age at surgery of 68 ± 10.6  years. A total of 89 implants were inserted in the posterior maxilla.Forty-seven patients were non-smokers, 9 smoked 5 cig/day, 1 patient 8 cig/day, 7 patients 10 cig/day and 2 patients smoked 15 cig/day . The folDifferent bone substitute materials were used for maxillary sinus augmentation . Patientp = 0.001), while despite a similar trend, it was not significantly different from zero when considering the percentage data (p = 0.49).p = 0.09) and in percentage (p = 0.18). This indicates that graft resorption in the vertical dimension is independent of the follow-up time.When vertical graft changes were correlated to follow-up duration, linear regression analysis showed that the slope was not significantly different from zero, both when considering the data in mm (p = 0.007), while despite a similar trend, it was not significantly different from zero when considering the percentage data (p = 0.12).p = 0.23) and in percentage (p = 0.47). This indicates that bone remodeling produces a significant dimensional reduction of the biomaterial in the mesiodistal dimension, which is independent of the follow-up time.When mesiodistal graft changes were correlated to follow-up duration, linear regression analysis showed that the slope was not significantly different from zero, both considering the data in mm (p = 0.17) nor in the vertical (p = 0.25) dimensions. Despite an apparent trend towards larger changes when reducing the granulometry of the grafts, both in the vertical and mesiodistal dimensions, there was no significant difference between groups, due to large within-group variability.The analysis of graft resorption in both mesiodistal and vertical dimensions according to the graft material used is synthesized in This study confirmed good performance from the sinus augmentation procedure under daily practice conditions, using different grafting materials of various origin . The same operator treated all patients, and the same evaluator performed all measurements, thereby minimizing a quote of the variability of results. The present study found that graft shrinkage in both horizontal and vertical dimensions is independent of the follow-up duration and irrespective of the graft material used. The first finding would imply that, once the graft remodeling occurs, the graft size tends to stabilize, showing minimal changes over time. The mean change in the mesiodistal and in the vertical dimensions amounted to about 10% and 5% of the graft size at placement. The mean graft height apical to implant apex averaged 1.8 mm at insertion and 1.06 mm after a mean of 82.3 months follow-up, thereby warranting long-term apical protection in the large majority of cases. A recent multicenter study on graft remodeling in transcrestal sinus floor elevation reported a median graft height apical to implant apex of 1.4 mm after 6–12 months follow-up (comparable to that observed in the present study), and a tendency to decrease at later follow-up intervals . That paThe dimensional change of the bone graft around implants after maxillary sinus augmentation is a longstanding matter of investigation. In fact, graft stability may represent an important prognostic factor for implant success in the long term ,39. Seve® Putty and OsteoBiol® Gel 40, were used alone in only 10 patients (13 grafts), while they were more frequently used in combination with other materials with greater particle size . OsteoBiol® Putty and OsteoBiol® Gel 40 used alone showed higher resorption in both dimensions, though not significantly, as compared to the other groups. This would suggest that, based on the present findings, OsteoBiol® Putty and OsteoBiol® Gel 40 might achieve better results when used in combination with other materials to preserve the graft size. Of course, due to the heterogeneity among different groups of materials and small sample sizes, this interpretation might be taken with caution. A few studies have investigated the effect of particle size on the graft healing outcomes; some reported better radiographic and histomorphometric results  for the grafts with larger particles [The fact that no significant difference in remodeling was found among the various groups of biomaterials was partly related to the high variability in outcomes and partly to the fact that some grafting materials were used in a small number of cases, as can be seen in articles ,54, whilarticles . HoweverAnother interesting finding is that in both vertical and horizontal dimensions, larger changes were associated with larger grafts (the linear regression slope was positive and significant in both cases, considering the changes in mm A. Greate® Putty in combination with Bioresorb, autogenous bone, or OsteoBiol® mp3®. Results obtained with OsteoBiol® GTO® are promising, but follow-up was relatively short, and long-term studies are necessary to validate its effectiveness.Another limitation of the present retrospective study was represented by the low number of samples for the different biomaterials used, which prevents a sound comparison of their performance. In fact, only for three types of graft were there at least ten samples; these included OsteoBiolIn conclusion, it was observed that all materials used in the present study for transcrestal maxillary sinus augmentation undergo a resorption pattern that depends on the baseline dimension of the graft—which could be related to the graft particle size—but were in all cases compatible with persistent implant protection and support.