Variable Screw Research Articles

Extrusion-Cooking Aspects and Physical Characteristics of Snacks Pellets with Addition of Selected Plant Pomace

The article presents the possibilities of using by-products from the agri-food industry in the form of fruit and vegetable pomace as a supplementary ingredient to extruded food products in the form of snack pellets. In the recipe based on potato starch, pomace from apples, chokeberries, pumpkin, nigella seed and flaxseed were added in amounts of 10%, 20% and 30%. The prepared raw material blends were processed using a single-screw extruder-cooker with a plastification system L/D = 20 and variable screw speed. The aim of the research was to determine the effect of pomace addition on the extrusion-cooking process, i.e., efficiency and energy consumption, as well as on selected physical properties of the obtained food pellets, such as expansion index, bulk density and durability. The addition of selected pomace influenced the extrusion-cooking process and the physical properties of the extrudates. A percentage contribution ranging from 10 to 20% can optimize the extrusion-cooking process and improve the quality characteristics of the final product, while simultaneously utilizing by-products from the agri-food industry and reducing their negative environmental impact.

Enhancement of ozone dissolution and oxidation treatment of phenolic wastewater by a static spiral shear rig with a variable screw pitch

A novel static spiral shear rig (SSSR) with variable screw pitch was developed to enhance the ozone–water mass transfer and the oxidative degradation of phenolic wastewater. The effects of critical operational parameters on the dissolution and mass transfer of ozone in water and the oxidative degradation rate of phenol were investigated with the proposed SSSR. Moreover, the mass transfer and oxidative degradation of phenols with the SSSR were compared to conventional static mixer (CSM) methods. The results showed that the mass transfer coefficient obtained with the SSSR is 5.33 times greater than that obtained with CSM. With the SSSR, the degradation percentage of phenolic wastewater with an initial concentration of 100 mg/L reached 97.09% within 12 min, and the reaction kinetic constant for phenol degradation obtained with the SSSR is 3.68 times higher than that obtained with the CSM. The SSSR dramatically enhances ozone dissolution and mass transfer, resulting in a higher phenol oxidative degradation percentage and a constant kinetic reaction.

Are Variable Screw Angle Change and Screw-to-Vertebral Body Ratio Associated With Radiographic Subsidence Following Anterior Cervical Discectomy and Fusion?

Retrospective Cohort. This study aims to assess the easily measurable radiographic landmarks of screw-to-vertebral body ratio and changes in screw angle to identify if they are associated with early subsidence following an Anterior cervical discectomy and fusion (ACDF). A retrospective cohort study was conducted on patients undergoing 1-3 level ACDF with allograft or PEEK cages. Preoperative, immediate postoperative, and 6-month postoperative radiographs were analyzed to measure intradiscal height (or distance between 2 vertebral bodies) as an anterior vertebral distance (AVD), middle (MVD), and posterior (PVD), screw angle, screw-to-vertebral body length ratio, and interscrew distance. Multivariate stepwise regression analyses were performed. 92 patients were included (42 single-level, 32 two-level, and 18 3-level ACDFs). In single-level ACDFs, a decrease in the caudal screw angle was associated with a decrease in AVD (=.001) and MVD (P = .03). A decrease in the PVD was associated with a decrease in segmental lordosis (P < .001). For two-level ACDFs, a higher caudal screw-to-body ratio was associated with a lower MVD (P = .01). Six months following an ACDF for degenerative pathology, a decrease in the caudal screw angle was associated with an increase in radiographic subsidence at the antero-medial aspect of the disc space albeit largely subclinical. This suggests that the caudal screw angle change may serve as a reliable radiographic marker for early radiographic subsidence. Furthermore, a greater screw-to-vertebral body ratio may be protective against radiographic subsidence in two-level ACDF procedures.

Cementing a Monoblock Dual-Mobility Implant into a Fully Porous Cup in Revision Total Hip Arthroplasty to Address Hip Instability: Surgical Technique.

Cementing a Monoblock Dual-Mobility Implant into a Fully Porous Cup in Revision Total Hip Arthroplasty to Address Hip Instability: Surgical Technique.

Corn-Based Gluten-Free Snacks Supplemented with Various Dried Fruits: Characteristics of Physical Properties and Effect of Variables

The market of extruded products is constantly growing and the incorporation of fruit items into their recipe, can made a crisp snack product a healthy one of acceptable flavor. The subject of this work is the evaluation of the effects of production screw speed, fruit type and amount on selected physical properties (expansion index, bulk density, water absorption and solubility, texture profile and color balance) of corn-based gluten-free crisps supplemented with various amounts (0–20%) of dried fruits (apple, white mulberry, goji berry, elderberry, blackberry) processed at variable screw speeds (80, 100 and 120 rpm). This work demonstrates that it is possible to obtain marketable extruded snacks with natural color coming from the incorporated dried fruits and with adequate expansion and texture if addition was up to 10% of all the tested fruits. Moreover, very good aeration, crispy texture and acceptable natural color was found if dried elderberry and blackberry were added to snacks even at 15 and 20%. Application of 15 or 20% of apple, white mulberry and goji berries showed similar color profiles and caused decrease in texture and expansion of snacks. The rotational screw speed effect differs significantly only in hardness and cutting force of the supplemented corn crisps.

LOQTEQ® VA Periprosthetic Plate-A New Concept for Bicortical Screw Fixation in Periprosthetic Fractures: A Technical Note.

Internal fixation using angle stable plates is the treatment standard in periprosthetic fractures around stable implants. To provide instant postoperative full weight-bearing, bicortical screw fixation is advisable but often surgically demanding. This work presents the first clinical results of the LOQTEQ® VA Periprosthetic Plate (aap Implantate AG, Berlin, Germany), a new plate system to simplify screw placement around implants. This plate system uses insertable hinges that allow for variable angle screw anchorage. Data of 26 patients with a mean age of 80 years and a mean follow-up of 13.9 months were retrospectively collected. Patients were clinically and radiologically examined. Bony union was achieved in 14 out of 15 patients with no signs of non-union or implant loosening. One patient, however, presented with implant failure. Clinical scores demonstrated acceptable results. Since the hinge plates are easy to apply, the first results are promising.

Effect of Composition and Processing Conditions on Selected Properties of Potato-Based Pellets and Microwave-Expanded Snacks Supplemented with Fresh Beetroot Pulp

The aim of this study was to evaluate the influence of the addition of fresh beetroot pulp in amounts from 2.5 to 30.0 g/100 g, as well as variable screw speeds (60, 80, 100 rpm) on the chemical composition, water absorption, water solubility index, density, expansion rate, and texture of potato-based pellets and expanded snacks. Their protein and starch structure was analyzed using the Fourier-transformed infrared (FTIR) spectroscopy. The snack pellets were made at a moisture content of 33 g/100 g of blends using a single-screw extruder equipped with a plasticizing unit having a length-to-diameter ratio (L/D) of 18. Processing temperature ranged from 65 to 105°C. The ready-to-eat snacks were expanded using microwave treatment (750 W, 40 s). Fresh vegetable pulp addition raised the protein content. The extrusion-cooking caused an increase in the content of insoluble dietary fiber and water absorption index of the pellets. In contrast, the microwave treatment reduced values of these parameters in expanded products and decreased the insoluble dietary fiber content of the expanded snacks. The addition of fresh beetroot pulp diminished the expansion ability and increased the content of β-sheet proteins. Additionally, an increase in the content of β-turn and β-sheet protein fractions was observed at the expense of random coil structure. This indicates that the protein structure underwent some form of ordering as the molecular interactions of the proteins intensified. The highest fraction of β-structures and the smallest content of random coil were observed when 80 rpm was applied during processing. It seems to be the most efficient screw speed in processing fresh beetroot pulp-supplemented snack pellets. Application of a fresh beetroot pulp as an additive in microwave expanded snacks made it possible to obtain products with an increased amount of fiber and a reduced fat content as an attractive and healthy alternative to deep-fried snacks.

Characteristics of Newly Developed Extruded Products Supplemented with Plants in a Form of Microwave-Expanded Snacks.

The following research focuses on the possibility of applying fresh plant material as a carrot pulp to supplement newly developed extruded products in the form of pellets and microwave-expanded snacks. Fresh carrot pulp, as a valuable vegetable ingredient, was used in the amount of 2.5 g/100 g to 30.0 g/100 g in a potato-based recipe. The snack pellets were processed via extrusion-cooking, using a single-screw extruder with a plasticizing unit L/D = 18, and the use of variable screw speeds. The produced pellets underwent microwave expansion to limit the fat content, so as to produce ready-to-eat (RTE) snacks. The pellets and snacks were tested for nutritional value, as well as for selected quality features: physical properties, structure, pasting characteristics, and texture profile, and PCA analysis and a correlation matrix were performed on the obtained results. Microwave expansion of pellets increased the total phenolic content, the antioxidant activity, water absorption index and lightness of snacks, but decreased the bulk density and setback values of the expanded products when compared to pellets. Generally, we found that it was possible to use up to 30.0 g/100 g of fresh carrot pulp with a positive effect on nutritional value, and without negative effects on the physical properties of extruded products. Both the extrusion-cooking and microwave expansion can minimize the negative impact on plant materials, due to the short processing time.

Comparison between selective caudal fixed screw construct and all variable screw construct in anterior cervical discectomy and fusion

This retrospective comparative study aimed to compare the efficacy of selective caudal fixed screw constructs with all variable screw constructs in anterior cervical discectomy and fusion (ACDF). Thirty-five patients who underwent surgery using selective caudal fixed screw construct (SF group) were compared with 44 patients who underwent surgery using all variable constructs (AV group). The fusion rate, subsidence, adjacent level ossification development (ALOD), adjacent segmental disease (ASD), and plate-adjacent disc space distance were assessed. The one-year fusion rates assessed by computed tomography bone bridging and interspinous motion as well as the significant subsidence rate did not differ significantly between the AV and SF groups. The ALOD and ASD rates and plate-adjacent disc space distances did not significantly differ between the two groups at both the cranial and caudal adjacent levels. The number of operated levels was significantly associated with pseudarthrosis in the logistic regression analysis. The stability provided by the locking mechanism of the fixed screw did not lead to an increased fusion rate at the caudal level. Therefore, the screw type should be selected based on individual patient’s anatomy and surgeon’s experience without concern for increased complications caused by screw type.

New type of potato-based snack-pellets supplemented with fresh vegetables from the Allium genus and its selected properties

The study aimed to determine the effect of the addition of fresh leek or onion pulp on selected properties of potato-based pellets and puffed snacks. In recipe, potato starch was replaced by vegetable pulp by 2.5–30.0 g/100 g. The pellets were then extruded at variable screw speed (60–100 rpm), dried and then fried in deep oil. The product was subsequently assessed for color profile, bulk density, water absorption and water solubility index, fat absorption, texture, as well as sensory attractiveness. The results showed that the addition of leek or onion pulp significantly influenced the color determinants of pellets and fried snacks, bulk density of expanded products, water absorption of pellets. The onion pulp addition significantly influenced the cutting force, water solubility, fat absorption, hardness and crispness, and the overall score during the sensory test but not so significant as leek addition. Moreover, the screw speed significantly influenced the value of water absorption (leek pellets, onion snacks) and water solubility (onion pellets and snacks), L* and b* coordinates in the case of onion puffs. Application of fresh Allium genus pulp could be an effective way to produce pellets and puffed snacks with good quality.

Bioink homogeneity control during 3D bioprinting of multicomponent micro/nanocomposite hydrogel for even tissue regeneration using novel twin screw extrusion system

The 3D bioprinting of an advanced multicomponent bioink requires the homogeneous distribution of bioink components to control the biological and structural properties of the printed tissue engineering construct. To ensure the homogeneous mixing of micro/nanomaterials in a bioink and then bioprinting, currently, multiple preparation steps must be followed before feeding the bioink to the conventional bioprinting extruder head. To overcome these limitations, a real-time one-step process was obtained by developing a semi-automated twin-screw extruder (TSE) head to synchronously perform systematic mixing and 3D bioprinting. In this study, as a proof of concept, the parameter optimizations for semi-automated mixing of bioink components and 3D bioprinting with the TSE head were demonstrated with an ionic gel (alginate), alpha-tricalcium phosphate (α-TCP) micro/nanoparticles, and osteoblast cells. The TSE-processed bioink samples showed better bioprintability, with better mechanical and biological properties than the conventional ones. The micro/nanoparticles were uniformly dispersed in the bioink within 60 s of screw mixing them inside the barrel (with the barrel outlet closed). The live cell distribution in the printed constructs was significantly superior to conventional mixing even with continuous feeding and extrusion-based bioink printing. This novel extrusion head ensured the control of uniform micro/nanomaterials and cell distribution throughout the directly mixed printable bioink with minimal cell damage. Further, they delivered increased batch consistency in real time mixing and bioink printing owing to its highly efficient variable screw pitch design. Higher repeatability than the conventional method of bioink component mixing and its subsequent 3D bioprinting was obtained through increased automation, as well as reduced processing time, demonstrating strong potential in tissue engineering applications through the controlled mixing of bioink components and its 3D bioprinting without damaging the cells.

Dynamic characteristic analysis of vertical screw conveyor in variable screw section condition.

Vertical screw conveyors are used widely in industry for elevating bulk materials over relatively short distances, but the problem of insufficient feeding and low conveying efficiency always exist in the vertical conveying process. In this paper, a vertical screw conveyor with variable screw section is presented, and the characteristics of vertical screw conveyor are investigated under the variable screw sections using discrete element method (DEM). The results show that the particle volume fraction in the inlet and the mass flow rate increase in the condition of variable screw section, and the screw rotational speed has a significant influence on mass flow rate. It is evident that the design of variable screw section provides an effective way in improving the particle feeding rate and the conveying efficiency.

Posterior atlantoaxial fixation with new subfacetal axis screw trajectory avoiding vertebral artery with customized variable screw placement plate and screws to enhance biomechanics of fixation.

Fixation for atlantoaxial dislocation is a challenging issue, and posterior C1 lateral mass and C2 pars–pedicle screw plate–rod construct is the standard of care for atlantoaxial instability. However, vertebral artery injury remains a potential complication. Recent literature has focused on intraoperative navigation, the O-arm, 3D printing, and recently use of robots for perfecting the trajectory and screw position to avoid disastrous injury to the vertebral artery and enhance the rigidity of fixation. These technological advances increase the costs of the surgery and are available only in select centers in the developed world.Review of the axis bone anatomy and study of the stress lines caused by weight transmission reveal that the bone below the articular surface of the superior facet is consistently dense as it lies along the line of weight transmission A new trajectory for the axis screw 3–5 mm below the midpoint of the facet joint and directed downward and medially avoids the course of the vertebral artery and holds the axis rigidly. Divergent screw constructs are biomechanically stronger. Variable screw placement (VSP) plates with long shaft screws permit manipulation of the vertebrae and realignment of the facets to the correct reduced position with fixation in the compression mode.The video can be found here: https://youtu.be/E1msiKjM-aA

Periprosthetic fractures of the shoulder girdle

Periprosthetic fractures of the shoulder girdle will increasingly become part of routine clinical practice due to rising numbers of joint replacements and the demographic changes. Diagnostically, the status of the rotator cuff, bed of the implant (stable or loose), type of shoulder arthroplasty as well as exclusion of joint infections are crucial for therapeutic decision-making. Novel imaging tools, such as dual-energy computed tomography provide improved preoperative planning options. The unified classification system describes the fracture location, stability of the prosthesis and quality of the bone. While nonoperative treatment is reserved for patients with severe pre-existing conditions and nondisplaced fractures, the standard treatment of fractures with a stable bed include fixation with cerclage wiring and angular stable plates. Modern implant systems with variable angle screw holes, attachment plates and hinges enable secure fixation around the stem. In cases of aloose stem revision arthroplasty is necessary. There are currently only alimited number of clinical studies with only few patients that analyzed clinical and radiological results. Thus, increased research efforts are indispensable in order to compare treatment options and improve treatment quality.

Possibility to Save Water and Energy by Application of Fresh Vegetables to Produce Supplemented Potato-Based Snack Pellets

The aim of the study was to examine the effect of fresh vegetable addition on processing efficiency, and to ascertain the energy and water consumption during production of potato-based snack pellets. The extrusion-cooking process with a modified single screw extruder was applied at variable screw speeds and amounts of vegetable additives. A mixture of potato flakes, potato grits and starch was used as a basic recipe. The potato composition was supplemented with fresh pulp of onion, leek, kale and carrot in amounts of 2.5–30.0% as replacement of a related amount of potato starch. The water consumption, as well as processing indicators: the production efficiency, the specific mechanical energy (SME), and the total SME requirements during snack pellets processing at the laboratory scale were evaluated. As a result of this work, we found that the amount of applied vegetable additives had little impact on both processing efficiency and SME depending on the screw speeds applied. Moreover, we saw increased processing efficiency with increased screw speed during extrusion. Of particular note, maximum value of processing efficiency was observed if fresh onion was used as an additive at the highest speed screw. Furthermore, the lowest specific mechanical energy consumption was noted for extrudates supplemented with fresh onion addition processed at the lowest screw speed. The most important limiting of water consumption during processing without negative effects on processing efficiency and quality of the final snack pellets was observed if 20% to 30% of fresh vegetables were used in the recipe. We believe that application of fresh vegetable pulp limited the energy requirements by mitigating the drying process of additives.

Analysing the effect of screw configuration using a stochastic twin-screw granulation model

In this work, a framework for modelling twin-screw granulation processes with variable screw configurations using a high-dimensional stochastic population balance method is presented. A modular compartmental approach is presented and a method for estimating residence times for model compartments based on screw element geometry is introduced. The model includes particle mechanisms for nucleation, primary particle layering, coalescence, breakage, and consolidation. A new twin-screw breakage model is introduced, which takes into account the differing breakage dynamics between two types of screw element. Additionally, a new sub-model for the layering of primary particles onto larger agglomerates is presented. The resulting model is used to simulate a twin-screw system with a number of different screw configurations and the predictive power of the model is assessed through comparison with an existing experimental data set in the literature. For most of the screw configurations simulated, the model predicts the product particle size distribution at large particle sizes with a reasonable degree of accuracy. However, the model has a tendency to over-predict the amount of fines in the final product. Nevertheless, the model qualitatively captures the reduction in fines associated with an increase in the number of kneading elements, as observed experimentally. Based on model results, a number of key areas for future model development are identified and discussed.

Steffee plating in management of fracture spine

Introduction: The diagnosis of a broken back has carried an ominous prognosis, since antiquity. In the writings of ancient Egyptians, as recorded in Edwn Smith papers, traumatic quadriplegia was considered a, “condition not to be treated “. However, with modern treatment, the outlook towards these patients have changed for the better. Results: Case series consisted of 33 cases, follow up period was from 5 months to 4 years. In most of the cases, implant removal was done after one to one and half years, depeding upon fusion, reduction & bone implant relationship. In most of the patients good fusion in reduced position with no loosening around implants were noted. Conclusion: Since pedicular screws & plates, Steffee variable screw placement (VSP type) fits on both sides of spine, they maintain the reduced and decompressed spine till such a time, when bony fusion occurs, since less load is shared by each plate.

Process Efficiency and Energy Consumption During the Extrusion of Potato and Multigrain Formulations

Abstract The aim of the research was to determine the effect of extrusion conditions (various moisture content of raw materials and screw rotation speed), as well as the effect of recipe composition on the process efficiency and the energy consumption during treatment of potato and multigrain products. The efficiency of the extrusion process (Q) was determined by the mass of the product obtained at a given time for all prepared raw material mixtures and the process parameters used, while the specific mechanical energy demand was determined using the SME index. The obtained results allow to conclude that the level of raw materials moisture content had a greater impact on the efficiency and energy consumption of the extrusion process than the variable screw speed during the treatment. The efficiency of the process increased with the increasing moisture of the tested compositions, while a decrease in the requirements of SME was observed. The use of differentiated raw material compositions also influenced the Q and SME values determined during the tests.

Clinical application of a minimally invasive cement-augmentable Schanz screw rod system to treat pelvic ring fractures.

The purpose of this study is to analyze the results using the USS fracture MIS system (DePuy Synthes) to treat instable pelvic ring fractures. As its outstanding feature, it is the only Schanz screw and rod system at present that combines angular stability, perforation/fenestration of the screws for cement-augmentation, a variable screw length, and a large screw diameter. Retrospective investigation of 134 pelvic ring fractures treated in 2012-2013. Twenty-five patients obtained the abovementioned implant. Besides baseline characteristics of the included patients and the surgical procedure, a clinical/radiological follow-up of sixmonths was analyzed. Dividing the collective into two groups, I high-energy trauma and II fragility fracture of the pelvis, the following results were recorded: group I: ten patients, six male, age 48.4 ± 19.7years. Mean ISS 41 ± 22.5, fracture classification: AO/OTA type 61 B1/C1/C3 = 1/5/4. Operative treatment: three transiliac internal fixator, seven iliolumbar fixation, one implant was cement-augmented. Group II: 15 patients, 14 female, age 77.5 ± 10.1years. Fracture classification according to Rommens: FFPII/III/IV = 6/1/8. Operative treatment: eight transiliac internal fixator, seven iliolumbar fixation, 14 implants were cement-augmented. Overall surgical side complications: 16%. Radiological examination: correct positioning of all ilium screws. Follow-up after sixmonth (16 patients): all showed fracture consolidation. One ilium screw was broken close to the connecting clamp. The investigated Schanz screw rod system is a suitable implant to broaden the established procedures to stabilize dorsal pelvic ring fractures. The study is registered at the Clinical Trial Registry University of Regensburg (Number Z-2017-0878-3).

Polyaxial locking plates in treating distal humeral fractures: a comparative randomized trial for clinical outcome

BackgroundManagement of distal humeral fractures remains to be one of the most challenging aspects in trauma surgery. Low profile plating systems with variable angle screw fixation represent a crucial advancement to the established angular stable locking plates with considerable attention in current research. The aim of the prospective randomized trial was to review the preliminary results and patients’ outcome following treatment with these newly developed implants and to rule out potential differences in fracture treatment of two different plating systems.MethodsTwenty patients with distal humeral fractures (AO 13-A1 – AO 13-C3) were included in the current study since 2014. After completing the randomization plan, patients were distributed into two groups for different variable angle locking plates (DePuy Synthes® VA-LCP vs. Medartis® Aptus Elbow). Functional elbow scoring (ROM, MEPS, QuickDASH) served as primary outcome parameter, while radiological fracture consolidation served as secondary outcome parameter. Follow-ups were conducted 6 weeks, 12 weeks, 6 months and 12 months after the operation.ResultsSeventeen of 20 patients (85%) concluded all follow-up examinations. Postoperative elbow extension deficiencies showed significant differences between the two groups in all follow-up examinations with a mean of Ø 18 +/− 7.4 degrees in the DePuy Synthes® VA-LCP group compared to a mean of Ø 6.5 +/− 7.5 degrees in the Medartis® Aptus Elbow group (p = 0.002) 12 months postoperatively. Functional scoring showed a disparate pattern. The Medartis® Aptus Elbow group achieved significantly better MEP scores during follow-up. However, the analysis of the QuickDash revealed better results of the DePuy Synthes® VA-LCP group in the first half and better results of the Medartis® Aptus Elbow group in the second half of the follow-up examination instead.ConclusionsConsidering the complexity of distal humeral fractures, the usage of anatomically preshaped low profile variable angle locking plates for operative treatment leads to good clinical results. Even though there might be some advances of the Medartis® Aptus Elbow plating system concerning postoperative ROM and elbow function, a consistent difference in the overall clinical outcome between the two plating systems could not be detected.Trial registrationhttps://clinicaltrials.gov/ct2/show/NCT03272490 Retrospectively Registered 1. September 2017.