Study on the Effect of Regeneration Agent on the Viscosity Properties of Aged Asphalt

China’s highway asphalt pavement has entered the stage of major repair, and improving the utilization rate of recycled asphalt pavement (RAP) is the main issue. The key link affecting the performance of recycled asphalt mixtures is the regeneration of aged asphalt, and the effect of the regenerant dosing on the high-temperature performance and viscosity of aged asphalt is the main content to be studied in this research. The aging behavior of asphalt seriously affects the roadworthiness of asphalt mixtures. In this study, we investigated the effect of changes in the microscopic properties of the aged asphalt on its viscosity properties during regeneration using gel permeation chromatography (GPC), Fourier-transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) as well as Brinell viscosity tests. This study simulated asphalt aging by the RTFOT test, and then we obtained an aged asphalt with a needle penetration of 30. We prepared different regenerated asphalts by adding regeneration agent with doses of 2%, 4%, and 6% to the aged asphalt. The results showed that the regeneration agent could effectively reduce the viscosity of the aged asphalt, which can play a positive role in improving the construction and ease of the aged asphalt. Rejuvenation agents affected the aging asphalt sulfoxide and carbon group indices. Moreover, rejuvenation agents can also significantly reduce the intensities of their characteristic functional group indices. The results of the AFM test showed that the increase in the dose of regeneration agent increased the number of the asphalt bee-like structures and decreased the area of individual bee-like structures. The results of the GPC test were consistent with the results of the AFM test, and the increase in the dose of regeneration agent reduced the asphalt macromolecule content. The viscosity properties and microstructure of the aged asphalt changed positively after the addition of the regeneration agent, indicating that the regeneration agent had a degrading and diluting effect on macromolecules.

In Situ Needle Penetration Test and Its Application in a Sericite Schist Railway Tunnel, Southwest of China

The sericite schist is a typical metamorphic soft rock. Large deformation of surrounding rock often occurs in the construction of a tunnel in this stratum. Due to the broken rock mass structure and poor mechanical strength in Baishitou tunnel project of Dalin line of Southwest railway, it is impossible to prepare standard samples for a traditional rock mechanical test. Therefore, we chose penetrometer (SH-70) for an in situ test. Firstly, we monitored the deformation of typical sections and analyzed the characteristics of large deformation of soft rock in the tunnel. Secondly, we tested the needle penetration index of fresh excavation face and side wall. Then, we estimated some mechanical parameters of sericite schist by a needle penetrometer and Hoek-brown criterion and discussed the acquisition of mechanical parameters of soft rock. The results show the following: (1) the characteristics of extrusion rock tunnel are summarized as large deformation, fast deformation rate, and obvious construction disturbance. (2) The reference value of penetration index of sericite schist (the vertical joint direction) is 3.90~7.77 N/mm, and the parallel joint direction is 1.27~2.99 N/mm. (3) The uniaxial compressive strength estimated by a penetrometer is 0.78~8.53 MPa, and the strength of the surrounding rock is negatively correlated with the amount of deformation. Therefore, it can be considered that the insufficient strength of surrounding rock is the fundamental reason for large deformation. (4) The reference value of cohesion of sericite schist estimated by a penetrometer is 0.203 MPa, and the reference value of internal friction angle is 18.224°. Compared with the common estimation methods, the penetrometer is more convenient and economical, which can provide a new idea for obtaining the mechanical parameters of sericite schist soft rock tunnel.

The “needle re-entry” technique for infrainguinal arterial calcified occlusive lesions

Background Vascular calcification is a predictor of poor clinical outcome during and after endovascular intervention. Guidewire crossing techniques and devices have been developed, but chronic total occlusions (CTOs) with severe calcification often prevent subintimal re-entry. We propose a novel guidewire crossing approach combined needle rendezvous with balloon snare technique, named the “needle re-entry” technique, for treatment of complex occlusive lesions. Main text A 73-year-old female with severe claudication in her right calf with ankle brachial index of 0.62, and a computed tomography angiogram showed a long occlusion with diffuse calcification in superficial femoral artery. She was referred to our department to have peripheral interventions. Since the calcified vascular wall of the lesion prevented the successful re-entry, the “needle re-entry” was performed. First, a retrograde puncture of the SFA, distally to the occlusion, was performed and an 0.018-in. guidewire with a microcatheter was inserted to establish a retrograde fashion. Second, an antegrade 5.0-mm balloon was advanced into a subintimal plane and balloon dilation at 6 atm was maintained. Third, an 18-gauge needle was antegradely inserted from distal thigh to the dilated 5.0-mm balloon. After confirming a balloon rupture by the needle penetration, we continued to insert the needle to meet the retrograde guidewire tip. Then, a retrograde 0.014-in. guidewire was carefully advanced into the needle hole, named the “needle rendezvous” technique. After further guidewire advancement to accomplish a guidewire externalization, the needle was removed. Finally, since the guidewire was passing through the 5.0-mm ruptured balloon, the balloon was withdrawn, and the guidewire was caught with the balloon and successfully advanced into the antegrade subintimal space, named the “balloon snare” technique. After the guidewire was advanced into the antegrade guiding sheath and achieved a guidewire externalization, an endovascular stent graft and an interwoven stent were deployed to cover the lesion. After postballoon dilation, an angiography showed a satisfactory result without complications. No restenosis, reintervention, and limb loss have been observed for one year follow-up period after this technique. Conclusions The “needle re-entry” technique is a useful guidewire crossing technique to revascularize femoropopliteal complex CTOs with severe calcification which prevent the achievement of guidewire crossing with the conventional procedures.

Going Hands-Free: MagnetoSuture™ for Untethered Guided Needle Penetration of Human Tissue Ex Vivo

The application of force in surgical settings is typically accomplished via physical tethers to the surgical tool. While physical tethers are common and critical, some internal surgical procedures may benefit from a tetherless operation of needles, possibly reducing the number of ports in the patient or the amount of tissue damage caused by tools used to manipulate needles. Magnetic field gradients can dynamically apply kinetic forces to magnetizable objects free of such tethers, possibly enabling ultra-minimally invasive robotic surgical procedures. We demonstrate the untethered manipulation of a suture needle in vitro, exemplified by steering through narrow holes, as well as needle penetration through excised rat and human tissues. We present proof of principle manipulations for the fully untethered control of a minimally modified, standard stainless steel surgical suture needle.

Detection of Reclaimed Asphalt Pavement Presence in Asphalt Mixtures Using a Method of Successive Asphalt Binder Extraction

The work deals with the detection of presence of RAP (reclaimed asphalt pavement) in asphalt mixtures. Information about the presence of RAP in an asphalt layer can be technically advantageous, for example, when planning further recycling of the layer. The method described in the paper can also be used to verify the success of a treatment of an aged binder in RAP, which is dosed in the production of new asphalt mixtures. The asphalt binder was obtained by a method of successive extraction from asphalt mixtures with different RAP content. Basic empirical tests of the asphalt binder (needle penetration and softening point) were chosen to detect the presence of RAP. The complex shear modulus G* was further determined on the extracted binders using a dynamic shear rheometer (DSR).

Methodology for Efficient Bitumen Storage with Reduced Energy Consumption

This paper studies the possibility of minimizing energy consumption during 35/50 bitumen storage. Similarly to most bitumen companies, the company with which we collaborated uses fossil fuel to maintain bitumen tanks at 150 °C. The main objective is to optimize energy usage. To achieve this purpose, we tested two new storage processes. One is based on dynamic temperature storage between 140 and 160 °C, and the other on room temperature conditions. This work evaluates the effect of these storage conditions on the quality of 35/50 bitumen, and studies the energy aspect to calculate the energy profit for every storage method. After storage, we have studied short-term and long-term ageing using the Rolling Thin Film Oven (RTFOT) and the Pressure Ageing Vessel (PAV) tests, respectively. We characterized the samples using needle penetration at 25 °C, the softening point, and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. We observed that the change in physical properties is negligible after the tested storage processes. Chemically, both the storage conditions affected the oxidative behavior acceptably; the carbonyl index was the same in the long term. We conclude that we can store 35/50 bitumen at room temperature conditions, which follow us to save more than three times the energy needs compared to the standard configurations.

Safety of Dry Needling of the Pronator Teres Muscle in Cadavers: A Potential Treatment for Pronator Syndrome

Background Entrapment of the median nerve at the pronator teres muscle can contribute to symptoms in the forearm and wrist. The pronator teres is also involved in patterns of spasticity observed in people who had suffered a stroke. Research on treatment efficacy with dry needling is scarce. Objective To determine if a solid filiform needle safely penetrates the pronator teres muscle during the clinical application of dry needling. Design A cadaveric descriptive study. Methods Needle insertion of the pronator teres was conducted in ten cryopreserved forearms with a 30 ×0.32 mm filiform needle. With the forearm supinated, the needle was inserted 3 cm distal to the mid-point between the biceps tendon insertion and the medial epicondyle. The needle was advanced in a cranial and medial direction to a depth clinically judged to be in the pronator teres muscle. Safety was assessed by measuring the distance from the needle to the surrounding neurovascular bundles. Results Accurate needle penetration of the pronator teres was observed in 100% of the specimens (mean needle penetration: 16.7 ± 4.3 mm, 95% confidence interval [CI] 13.6 to 19.7 mm). No neurovascular bundles were pierced in any of the specimen’s forearms. The distances from the tip of the needle to the surrounding neurovascular bundles were 16.4 ± 3.9 mm (95% CI 13.6 to 19.2 mm) to the ulnar nerve (A), 9.0 ± 2.2 mm (95% CI 7.3 to 19.5 mm) to the median nerve (B), and 12.8 ± 4.0 mm (95% CI 10.0 to 15.7 mm) to brachial artery (C). Conclusions The results from this cadaveric study support the assumption that needling of the pronator teres using described anatomical landmarks can be accurately and safely conducted by an experienced clinician.

Is Dry Needling of the Supinator a Safe Procedure? A Potential Treatment for Lateral Epicondylalgia or Radial Tunnel Syndrome. A Cadaveric Study

The supinator muscle is involved in two pain conditions of the forearm and wrist: lateral epicondylalgia and radial tunnel syndrome. Its close anatomical relationship with the radial nerve at the arcade of Frohse encourages research on dry needling approaches. Our aim was to determine if a solid filiform needle safely penetrates the supinator muscle during the clinical application of dry needling. Needle insertion of the supinator muscle was conducted in ten cryopreserved forearm specimens with a 30 × 0.32 mm filiform needle. With the forearm pronated, the needle was inserted perpendicular into the skin at the dorsal aspect of the forearm at a point located 4cm distal to the lateral epicondyle. The needle was advanced to a depth judged to be in the supinator muscle. Safety was assessed by measuring the distance from the needle to the surrounding neurovascular bundles of the radial nerve. Accurate needle penetration of the supinator muscle was observed in 100% of the forearms (needle penetration:16.4 ± 2.7 mm 95% CI 14.5 mm to 18.3 mm). No neurovascular bundle of the radial nerve was pierced in any of the specimen’s forearms. The distances from the tip of the needle were 7.8 ± 2.9 mm (95% CI 5.7 mm to 9.8 mm) to the deep branch of the radial nerve and 8.6 ± 4.3 mm (95% CI 5.5 mm to 11.7 mm) to the superficial branch of the radial nerve. The results from this cadaveric study support the assumption that needling of the supinator muscle can be accurately and safely conducted by an experienced clinician.

Needle penetration test - qualifying examination of 3D printable silicones for vascular models in surgical practice

Background During cardiogenic shock blood circulation is minimal in the human body and does not suffice to survive. The extracorporeal life support system (ECLS) acts as a miniature heart-lung-machine that can be temporarily implanted over major vessels e.g. at the groin of the patient to bridge cardiogenic shock. To perform this procedure in an emergency, a proper training model is desirable. Therefore, a 3-dimensional-printable (3D) material must be found that mimics large vessel needle penetration properties. A suitable test bench for material comparison is desirable. Methods A test setup was built, which simulated the clinically relevant wall tension in specimens. The principle was derived from an existing standardized needle penetration test. After design, the setup was fabricated by means of 3D printing and mounted onto an universal testing machine. For testing the setup, a 3D printable polymer with low Shore A hardness and porcine aorta were used. The evaluation was made by comparing the curves of the penetration force to the standardized test considering the expected differences. Results 3D printing proved to be suitable for manufacturing the test setup, which finally was able to mimic wall tension as if under blood pressure and penetration angle. The force displacement diagrams showed the expected curves and allowed a conclusion to the mechanical properties of the materials. Although the materials forces deviated between the porcine aorta and the Agilus30 polymer, the graphs showed similar but still characteristic curves. Conclusions The test bench provided the expected results and was able to show the differences between the two materials. To improve the setup, limitations has been discussed and changes can be implemented without complications.