Experimental study of the bond behavior of 400MPa grade hot-rolled ribbed steel bars in steel fibre reinforced concrete

Present studies show that steel fibres can improve the bond of steel bar in steel fibre reinforced concrete (SFRC) with a correlation to the fibre factor and the fibre distribution uniformity. As a foundation of high-flowability SFRC working together with 400 MPa grade hot-rolled ribbed (HRB400) steel bar in reinforced structures, the bond between them was evaluated through a series of pull-out testing on 48 specimens with a central arranged steel bar. The bond behaviours of steel bar were estimated with a constant bond length of 5d (d is the diameter of steel bar) embedded in high-flowability SFRC, the main research parameters included the ingot mill steel fibres with a fibre volume fraction varied from 0.8 to 2.0%, the strength grade C40 and C50 of SFRC or referenced conventional concrete, and the diameter of steel bars varied from 14 to 20 mm. Results showed that the high-flowability SFRC compacted with a slight vibration is beneficial to improve the bond failure pattern since steel fibres effectively eliminate the crack appeared on the SFRC blocks during the pulling out of steel bar, leading to all specimens failed with the steel bar pull out of SFRC blocks. The bond strength was dominant by the SFRC strength, and obviously strengthened with the increase of fibre volume fraction, while the peak-slip was slightly influenced by the diameter of steel bar. By conducting analyses of test data, equations for calculating the bond strength and the peak-slip are proposed accounting for the effect of steel fibres. Then the predicting method for the anchorage length is suggested linking with different design codes for concrete structures. Compared with test results of this study, a little shorter anchorage length of steel bar in SFRC is obtained from the specification of Chinese code JGJ/T46, which should be noticed to ensure a rational anchorage of ribbed steel bar in SFRC with ingot mill steel fibres.

[Intermediate and long-term outcomes of transcatheter closure of congenital coronary cameral fistulas in 66 children]

Objective: To evaluate the intermediate and long-term outcomes and technical aspects of transcatheter closure (TCC) of coronary cameral fistulas (CCF) in pediatric patients. Methods: This was a case-control study. All pediatric patients with CCF who underwent TCC between January 2005 and December 2019 were retrospectively reviewed. Data was collected from medical records, including demographic characteristics, procedural details, intraoperative and postoperative serious adverse events, follow-up results and prognosis. Patients with serious adverse events and without serious adverse events were compared regarding their clinical features and CCF characteristics. Comparisons between groups were performed with independent sample t test, chi-square test or Fisher exact test. Results: A total of 66 CCF patients (34 boys, 32 girls, 3.9 (1.9, 6.2) years old, 15 (11, 20) kg) underwent attempted TCC. All of the CCF were all medium or large fistulas including 55 proximal fistulas (83%) and 11 distal fistulas (17%). The CCF originated more frequently from the right coronary artery (38 cases (58%)), followed by the left coronary artery (28 cases (42%)). The incidence of coronary artery aneurysms (CAA) was 61% (40/66).Procedural treatment was achieved in 64 patients and procedural success was achieved in 59 patients (92%). Six (9%) serious adverse events occurred in 5 patients during the perioperative period. Acute complications included procedure-related death in one patient and acute myocardial infarction in one patient. Periprocedural complications occurred in 3 patients at one day postoperatively including acute myocardial infarction (2 cases), occluder detachment (1 case), and tricuspid chordae tendinae rupture (1 case). Clinical follow-up data were available in 58 of the 62 patients who underwent initial successful TCC with a follow-up period of 9.3 (6.5, 13.4) years. Ten adverse events occurred in 9 patients including 5 complications consisted of aortic valve perforation (1 case), coronary thrombosis (1 case), progressive aneurysmal dilation after reintervention (1 case), and new-onset tricuspid valve prolapse with significant regurgitation (2 cases) and large residual shunts due to fistula recanalization (5 cases). Therefore, the incidence of intermediate and long-term adverse events was 17% (10/58). During the periprocedural and follow-up period, 16 adverse events occurred in 13 patients, whereas no adverse events occurred in 51 patients. Patients with seriovs adverse events presented with larger proportion of large CCF (11/13 vs. 39% (20/51), P=0.005), giant CAA (10/13 vs.14% (7/51), P=0.030), and higher mean pulmonary artery pressure ((20±9) vs.(16±6) mmHg, 1 mmHg=0.133 kPa, t=2.02, P=0.048) compared to patients without serious adverse events. Conclusions: TCC in CCF children appears to be effective with favorable intermediate and long-term outcomes. Strict indication of TCC is mandatory.

A self-adapting woven net trap based on the evolution mechanism of orb-web topology

The development of structures that can adapt spontaneously to achieve desired functions in complex environments is crucial for new unmanned countermeasures, such as prey capture or net-recovery. Conventional structural optimization methods based on a singular net-like configuration may lead to functional limitations and fail to achieve specific objectives. In this study, we utilized an evolutionary algorithm that incorporated mechanical features and biological corrections to construct spider threads with advanced properties capable of efficient and reliable trapping behavior in arbitrary boundary conditions. We employed distinct thread types in different components, which achieved distinguished stiffness and strength that could not be accomplished by a single kind of thread. By assembling prestress reinforcement threads, we developed an orb-web-like trap that demonstrated effective trapping performance in experiments. The adaptive evolutionary method could be applied to design intelligent intercepting devices suited to particular functions and extreme environments, with wide application prospects in net-recovery system of UAV. STATEMENT OF SIGNIFICANCE: Structures that adapt spontaneously to perform desired functions in difficult environments are crucial for rising unmanned countermeasures. Conventional structural optimization methods based on a singular net-like configuration may lead to functional limitations and fail to achieve specific objectives. We used an evolutionary algorithm that combined mechanical features and biological corrections to create spider threads in arbitrary boundary circumstances in this work. The adaptive evolutionary method could be applied to design intelligent intercepting devices suited to particular functions and extreme environments, with wide application prospects in net-recovery system of UAV.

A Numerical Modelling Framework for Investigating the Ballistic Performance of Bio-Inspired Body Armours

Biological structures possess excellent damage tolerance, which makes them attractive for ballistic protection applications. This paper develops a finite element modelling framework to investigate the performance of several biological structures that are most relevant for ballistic protection, including nacre, conch, fish scales, and crustacean exoskeleton. Finite element simulations were conducted to determine the geometric parameters of the bio-inspired structures that can survive projectile impact. The performances of the bio-inspired panels were benchmarked against a monolithic panel with the same 4.5 mm overall thickness and projectile impact condition. It was found that the biomimetic panels that were considered possessed better multi-hit resistant capabilities compared to the selected monolithic panel. Certain configurations arrested a fragment simulating projectile with an initial impact velocity of 500 m/s, which was similar to the performance of the monolithic panel.

Extending Goldberg's method to parametrize and control the geometry of Goldberg polyhedra

Goldberg polyhedra have been widely studied across multiple fields, as their distinctive pattern can lead to many useful applications. Their topology can be determined using Goldberg's method through generating topologically equivalent structures, named cages. However, the geometry of Goldberg polyhedra remains underexplored. This study extends Goldberg's framework to a new method that can systematically determine the topology and effectively control the geometry of Goldberg polyhedra based on the initial shapes of cages. In detail, we first parametrize the cage's geometry under specified topology and polyhedral symmetry; then, we manipulate the predefined independent variables through optimization to achieve the user-defined geometric properties. The benchmark problem of finding equilateral Goldberg polyhedra is solved to demonstrate the effectiveness of the proposed method. Using this method, we have successfully achieved nearly exact spherical Goldberg polyhedra, with all vertices on a sphere and all faces being planar under extremely low numerical errors. Such results serve as strong numerical evidence for the existence of this new type of Goldberg polyhedra. Furthermore, we iteratively perform k-means clustering and optimization to significantly reduce the number of different edge lengths to benefit the cost reduction for architectural and engineering applications.

Topology of leaf veins: Experimental observation and computational morphogenesis

The unique, hierarchical patterns of leaf veins have attracted extensive attention in recent years. However, it remains unclear how biological and mechanical factors influence the topology of leaf veins. In this paper, we investigate the optimization mechanisms of leaf veins through a combination of experimental measurements and numerical simulations. The topological details of three types of representative plant leaves are measured. The experimental results show that the vein patterns are insensitive to leaf shapes and curvature. The numbers of secondary veins are independent of the length of the main vein, and the total length of veins increases linearly with the leaf perimeter. By integrating biomechanical mechanisms into the topology optimization process, a transdisciplinary computational method is developed to optimize leaf structures. The numerical results show that improving the efficiency of nutrient transport plays a critical role in the morphogenesis of leaf veins. Contrary to the popular belief in the literature, this study shows that the structural performance is not a key factor in determining the venation patterns. The findings provide a deep understanding of the optimization mechanism of leaf veins, which is useful for the design of high-performance shell structures.

P4166Efficacy and safety of novel biodegradable device for closure of atrial septal defect: from preclinical study to first-in-man experience

Background

closure of atrial septal defect (ASD) has emerged as the treatment of choice for the majority of defect. The biodegradable ASD closure device is a novel, absorbable device made of poly-L_latic acid (PLLA). This study evaluates the feasibility, safety and effectiveness of PLLA biodegradable ASD closure device in a swine model and for the first time in human.

Objective

The study reports on the 24- and 36- month follow-up results of PLLA device implanted in a swine model and the first-in- man experience with 6-month follow-up.

Method

Preclinical study was done in a swine ASD model. In a clinical setting, 5 pediatric patients with a secundum ASD who a clinically left-to-right shunt were enrolled in our center. Percutaneous ASD closure procedure with PLLA device was performed with fluoroscopic and transcatheter echocardiography (TTE) guidance. Procedure results and clinical outcomes at 1 day, 30 days, 3 months and 6 months after closure procedure were analyzed.

Results

24- and 36-month follow-up results of preclinical study demonstrated that the PLLA device exhibited good endothelialization and degradability in a swine model. In clinical study, device implantation was successfully achieved in all of 5 patients (median age, 3.6 years; range, 3.1–6.5 years). The mean ASD size was (13.4±2.4)mm (range, 10–16mm). The mean pulmonary-to-systemic blood flow ratio (Qp:Qs) was (1.7±0.2):1 with a range of 1.5:1 to 2.0:1. The mean procedure time and the mean fluoroscopy time were (36.2±11.3) and (6.4±1.0)minutes, respectively. There was no evidence of short-term complications related to the device or the delivery system. No device dislodgement, significant aortic valve or mitral valve regurgitation, new onset cardiac arrhythmia, or other adverse events were reported.

Characteristics and procedure data of the 5 patients who underwent ASD closure procedure with PLLA device Patient No. Age Weight Gender Defect size Qp:Qs Mean Pulmonary Pressure Device size (mm) Sheath (Fr) Procedure time Fluoroscopy time Immediate residual shunt (years) (kg) (mm) (mmHg) (mm) (Fr) (min) (min) 1 4.9 23.5 Male 17 1.7:1 22 24 12 52 7.6 None 2 3.1 10.0 Male 14 2.0:1 19 20 12 26 5.4 None 3 6.5 21.0 Male 15 1.8:1 22 20 12 31 6.0 None 4 3.2 14.5 Female 12 1.5:1 13 18 10 44 7.3 None 5 3.6 12.5 Male 10 1.5:1 17 14 10 28 5.5 None

Conclusion

This study is the first to demonstrate the feasibility, safety and effectiveness of PLLA biodegradable device in human, with no evidence of short-term complications and a high rate of early shunt closure.

Acknowledgement/Funding

National Key R&D Program of China (Grant Number: 2016 YFC1100305)

Additive manufacturing of specific ankle-foot orthoses for persons after stroke: A preliminary study based on gait analysis data

The aim of present study is to investigate the feasibility of patient-specific ankle-foot orthoses fabricated using additive manufacturing (AM) techniques. Then, clinical performance of the AFOs manufactured using material PA12 was evaluated in stroke survivors based on gait analysis data. The ankle and foot were scanned by EinScan-Pro 3D scanner. The software Geomagic Studio was used for modifying the AFO model. After processing the original AFO model into the final required model, material PA12 were used to fabricate the AFOs by Multi Jet Fusion (MJF) technique. Finally, gait analysis of 12 stroke patients was conducted to compare the effects with and without AFO. It took 2 hours from processing the initial AFO model to the completion of final model, and the printing time was 8 hours. The printing thickness of the AFO was 1.2 mm. With respect to the temporal-spatial parameters, the velocity and stride length in the gait with AFO increased significantly as compared to the gait without AFO (P=0.001, P=0.002). The cadence increased, double limb support phase decreased, and the step length difference decreased in the gait with AFO; however, the difference was not statistically significant (P=0.117, P=0.075, P=0.051).This study confirmed the feasibility of patient-specific AFO fabricated by AM techniques, and demonstrated the process of modifying AFO models successfully. The specific ankle-foot orthoses fabricated by material PA12 have a significant effect on the improvement of velocity and stride length in people with stroke.

Comparison of Mechanical Properties and Energy Absorption of Sheet-Based and Strut-Based Gyroid Cellular Structures with Graded Densities

Bio-inspired functionally graded cellular materials (FGCM) have improved performance in energy absorption compared with a uniform cellular material (UCM). In this work, sheet-based and strut-based gyroid cellular structures with graded densities are designed and manufactured by stereo-lithography (SLA). For comparison, uniform structures are also designed and manufactured, and the graded structures are generated with different gradients. The mechanical behaviors of these structures under compressive loads are investigated. Furthermore, the anisotropy and effective elastic modulus of sheet-based and strut-based unit gyroid cellular structures are estimated by a numerical homogenization method. On the one hand, it is found from the numerical results that the sheet-based gyroid tends to be isotropic, and the elastic modulus of sheet-based gyroid is larger than the strut-based gyroid at the same volume fraction. On the other hand, the graded cellular structure has novel deformation and mechanical behavior. The uniform structure exhibits overall deformation and collapse behavior, whereas the graded cellular structure shows layer-by-layer deformation and collapse behavior. Furthermore, the uniform sheet-based gyroid is not only stiffer but also better in energy absorption capacity than the uniform strut-based gyroid structure. Moreover, the graded cellular structures have better energy absorption capacity than the uniform structures. These significant findings indicate that sheet-based gyroid cellular structure with graded densities have potential applications in various industrial applications, such as in crashworthiness.

Thermal shrinkage and stability of diamondene nanotubes

By curving a rectangular diamondene, an sp ²/sp ³ composite carbon film, a diamondene nanotube (DNT) can be formed when the two straight edges are sewn together. In this study, thermal stabilities of DNTs are investigated using molecular dynamics simulation approaches. An interesting thermal shrinkage of damaged DNTs is discovered. Results indicate that DNTs have critical temperatures between 320 K and 350 K. At temperatures higher than the critical value, the interlayer bonds, i.e., the sp ³-sp ³ bonds, may break. The broken ratio of the interlayer bonds mainly depends on the temperature. For the DNT with a high broken ratio of interlayer bonds, it has thermal shrinkage in both the cross section and tube axis. The sp ²-sp ³ bonds in either the inner or the outer surface are much more stable. Even at 900 K, only a few sp ²-sp ³ bonds break. These properties can be used in the design of metamaterials.

Coupling effect of van der Waals, centrifugal, and frictional forces on a GHz rotation-translation nano-convertor

A nano rotation-translation convertor with a deformable rotor is presented, and the dynamic responses of the system are investigated considering the coupling among the van der Waals (vdW), centrifugal and frictional forces. When an input rotational frequency (ω) is applied at one end of the rotor, the other end exhibits a translational motion, which is an output of the system and depends on both the geometry of the system and the forces applied on the deformable part (DP) of the rotor. When centrifugal force is stronger than vdW force, the DP deforms by accompanying the translation of the rotor. It is found that the translational displacement is stable and controllable on the condition that ω is in an interval. If ω exceeds an allowable value, the rotor exhibits unstable eccentric rotation. The system may collapse with the rotor escaping from the stators due to the strong centrifugal force in eccentric rotation. In a practical design, the interval of ω can be found for a system with controllable output translation.

Systematic Review of Acupuncture Placebo Devices with a Focus on the Credibility of Blinding of Healthy Participants And/Or Acupuncturists

Background

An ideal placebo design in clinical research should resemble the intervention under investigation to facilitate blinding, yet remain clinically inert. With regard to physical interventions such as acupuncture, a true placebo device has not been developed and validated. Since 1998, researchers have designed several placebo acupuncture devices (PADs). The three most widely used PADs are the Streitberger, the Park and the Takakura device.

Aim

This review focuses on evaluating studies of these devices, in the context of credibility of blinding (COB), assessment of penetrating pain or sensation, and de qi sensation.

Methods

Electronic database searches were conducted in four English and two Chinese databases from their inception until November 2016. All studies included in the review were conducted on healthy participants and compared verum manual acupuncture with any of the aforementioned PADs with respect to one or more of the above three outcomes related to blinding effect.

Results

The synthesised analyses of the 15 included studies showed that the Streitberger and Park placebo devices may not blind participants successfully when tested at a sensitive acupuncture point (LI4). In terms of penetrating sensation, there were significant differences between these two placebo devices and verum acupuncture when applied at this point. The Takakura device was the only PAD that had the potential to blind the acupuncturist. However, the blinding analyses of all outcome measures were inconsistent.

Conclusion

Overall, there were insufficient data to confirm the blinding effects of these skin-contact PADs as each device was associated with limitations that warrant further design improvements.

Shell buckling: from morphogenesis of soft matter to prospective applications

Being one of the commonest deformation modes for soft matter, shell buckling is the primary reason for the growth and nastic movement of many plants, as well as the formation of complex natural morphology. On-demand regulation of buckling-induced deformation associated with wrinkling, ruffling, folding, creasing and delaminating has profound implications for diverse scopes, which can be seen in its broad applications in microfabrication, 4D printing, actuator and drug delivery. This paper reviews the recent remarkable developments in the shell buckling of soft matter to explain the most representative natural morphogenesis from the perspectives of theoretical analysis in continuum mechanics, finite element analysis, and experimental validations. Imitation of buckling-induced shape transformation and its applications are also discussed for the innovations of sophisticated materials and devices in future.

Examination of needle surface corrosion in electroacupuncture

BACKGROUND

Electroacupuncture (EA) is a modern form of acupuncture therapy where stainless steel acupuncture needles are used as percutaneous electrodes to apply electrical stimulation. The concern about electrolytic corrosion of needles during EA has not been conclusively addressed.

AIM

To examine whether corrosion of stainless steel acupuncture needles occurs after EA to establish the safety profile of this therapy.

METHODS

The study comprised four EA sessions on healthy participants mimicking a common clinical practice, with needle surface examinations conducted immediately after each session. Used acupuncture needles that did not undergo electrical stimulation and unused needles taken from the original package were also examined as control comparisons. Two commonly used types of single-use, silicone-coated, stainless steel needles were selected for the experiment. The ES-160 digital acupunctoscope (a charge-balanced electric stimulator) was used to deliver electrical stimulation, and an oscilloscope was used to record the waveforms and electric currents. All needles were sterilised before examination by a scanning electron microscope (SEM), where images of needle tips and shafts were taken for further analysis.

RESULTS AND CONCLUSIONS

32 needles were examined under the SEM. As the main findings, the SEM images showed the surface finish, burr attachments and surface characteristics of needle samples. No evidence of electrolytic corrosion was detected on any needle that underwent electrical stimulation for 30 min delivered by a charge-balanced acupunctoscope in healthy participants. The choice of a charge-balanced acupunctoscope is recommended to avoid any potential corrosion of needles in EA clinical practice.

A nano continuous variable transmission system from nanotubes

A nano continuous variable transmission (nano-CVT) system is proposed by means of carbon nanotubes (CNTs). The dynamic behavior of the CNT-based nanosystem is assessed using molecular dynamics simulations. The system contains a rotary CNT-motor and a CNT-bearing. The tube axes of the nanomotor and the rotor in the bearing are laid in parallel, and the distance between them is known as the eccentricity of the rotor with a diameter of d. By changing the eccentricity (e) of the rotor from 0 to d, some interesting rotation transmission phenomena are discovered, whose procedures can be used to design various nanodevices. This might include the failure of rotation transmission-i.e. the rotor has no rotation-when e ≥ d at an extremely low temperature, or when the edges of the two tubes are orthogonal at their intersections in any condition. This hints that the state of the nanosystem can be used as an on/off switch or breaker. For a system with e = d and a high temperature, the rotor rotates in the reverse direction of the motor. This means that the output signal (rotation) is the reverse of the input signal. When changing the eccentricity from 0 to d continuously, the output signal gradually decreases from a positive value to a negative value; as a result a nano-CVT system is obtained.

Softening to hardening of stretched diamondene nanotubes

Diamondene nanotubes rolled from 2D diamondene exhibit a softening-to-hardening transition under axial tension.

High-speed spinning disks on flexible threads

A common spinning toy, called “buzzer”, consists of a perforated disk and flexible threads. Despite of its simple construction, a buzzer can effectively transfer translational motions into high-speed rotations. In the present work, we find that the disk can be spun by hand at an extremely high rotational speed, e.g., 200,000 rpm, which is much faster than the previously reported speed of any manually operated device. We explore, both experimentally and theoretically, the detailed mechanics and potential applications of such a thread–disk system. The theoretical prediction, validated by experimental measurements, can help design and optimize the system for, e.g., easier operation and faster rotation. Furthermore, we investigate the synchronized motion of multiple disks spinning on a string. Distinctly different twist waves can be realized by the multi-disk system, which could be exploited in the control of mechanical waves. Finally, we develop two types of manually-powered electric generators based on the thread–disk system. The high-speed rotation of the rotors enables a pulsed high current, which holds great promise for potential applications in, for instance, generating electricity and harvesting energy from ocean waves and other rhythmic translational motions.

On the shape transformation of cone scales

The shape-morphing behaviours of some biological systems have drawn considerable interest over many years. This paper divulges that the opening and closing mechanism of pine cones is attributed to the self-bending of their scales, which undergo three states of humidity-driven deformation in terms of Föppl-von Kármán plate theory. Both numerical simulation and experimental measurement support the theoretical analysis, showing that the longitudinal principal curvature and the transverse principal curvature bifurcate at a critical humidity level according to the thickness and shape of scales. These findings help us understand the shape transformation of bilayer or multi-layer natural structures and gain insights into the design of transformable devices/materials with great potential in numerous applications.

A finite-element approach to evaluating the size effects of complex nanostructures

The size effects that reveal the dramatic changes of mechanical behaviour at nanoscales have traditionally been analysed for regular beam systems. Here, the method of using finite-element analysis is explored with the intention of evaluating the size effects for complex nanostructures. The surface elasticity theory and generalized Young-Laplace equation are integrated into a beam element to account for the size effects in classical Euler-Bernoulli and Timoshenko beam theories. Computational results match well with the theoretical predictions on the size effect for a cantilever beam and a cubic unit cell containing 24 horizontal/vertical ligaments. For a simply supported nanowire, it is found that the results are very close to the experimental data. With the assumption that nanoporous gold is composed of many randomly connected beams, for the first time, the size effect of such a complex structure is numerically determined.

A Kirigami Approach to Forming a Synthetic Buckliball

The shape transformation of some biological systems inspires scientists to create sophisticated structures at the nano- and macro- scales. However, to be useful in engineering, the mechanics of governing such a spontaneous, parallel and large deformation must be well understood. In this study, a kirigami approach is used to fold a bilayer planar sheet featuring a specific pattern into a buckliball under a certain thermal stimulus. Importantly, this prescribed spherical object can retract into a much smaller sphere due to constructive buckling caused by radially inward displacement. By minimizing the potential strain energy, we obtain a critical temperature, below which the patterned sheet exhibits identical principal curvatures everywhere in the self-folding procedure and above which buckling occurs. The applicability of the theoretical analysis to the self-folding of sheets with a diversity of patterns is verified by the finite element method.

Tuning the Performance of Metallic Auxetic Metamaterials by Using Buckling and Plasticity

Metallic auxetic metamaterials are of great potential to be used in many applications because of their superior mechanical performance to elastomer-based auxetic materials. Due to the limited knowledge on this new type of materials under large plastic deformation, the implementation of such materials in practical applications remains elusive. In contrast to the elastomer-based metamaterials, metallic ones possess new features as a result of the nonlinear deformation of their metallic microstructures under large deformation. The loss of auxetic behavior in metallic metamaterials led us to carry out a numerical and experimental study to investigate the mechanism of the observed phenomenon. A general approach was proposed to tune the performance of auxetic metallic metamaterials undergoing large plastic deformation using buckling behavior and the plasticity of base material. Both experiments and finite element simulations were used to verify the effectiveness of the developed approach. By employing this approach, a 2D auxetic metamaterial was derived from a regular square lattice. Then, by altering the initial geometry of microstructure with the desired buckling pattern, the metallic metamaterials exhibit auxetic behavior with tuneable mechanical properties. A systematic parametric study using the validated finite element models was conducted to reveal the novel features of metallic auxetic metamaterials undergoing large plastic deformation. The results of this study provide a useful guideline for the design of 2D metallic auxetic metamaterials for various applications.

Topological design and additive manufacturing of porous metals for bone scaffolds and orthopaedic implants: A review

One of the critical issues in orthopaedic regenerative medicine is the design of bone scaffolds and implants that replicate the biomechanical properties of the host bones. Porous metals have found themselves to be suitable candidates for repairing or replacing the damaged bones since their stiffness and porosity can be adjusted on demands. Another advantage of porous metals lies in their open space for the in-growth of bone tissue, hence accelerating the osseointegration process. The fabrication of porous metals has been extensively explored over decades, however only limited controls over the internal architecture can be achieved by the conventional processes. Recent advances in additive manufacturing have provided unprecedented opportunities for producing complex structures to meet the increasing demands for implants with customized mechanical performance. At the same time, topology optimization techniques have been developed to enable the internal architecture of porous metals to be designed to achieve specified mechanical properties at will. Thus implants designed via the topology optimization approach and produced by additive manufacturing are of great interest. This paper reviews the state-of-the-art of topological design and manufacturing processes of various types of porous metals, in particular for titanium alloys, biodegradable metals and shape memory alloys. This review also identifies the limitations of current techniques and addresses the directions for future investigations.

Placebo Devices as Effective Control Methods in Acupuncture Clinical Trials: A Systematic Review

While the use of acupuncture has been recognised by the World Health Organisation, its efficacy for many of the common clinical conditions is still undergoing validation through randomised controlled trials (RCTs). A credible placebo control for such RCTs to enable meaningful evaluation of its efficacy is to be established. While several non-penetrating acupuncture placebo devices, namely the Streitberger, the Park and the Takakura Devices, have been developed and used in RCTs, their suitability as inert placebo controls needs to be rigorously determined. This article systematically reviews these devices as placebo interventions. Electronic searches were conducted on four English and two Chinese databases from their inceptions to July 2014; hand searches of relevant references were also conducted. RCTs, in English or Chinese language, comparing acupuncture with one of the aforementioned devices as the control intervention on human participants with any clinical condition and evaluating clinically related outcomes were included. Thirty-six studies were included for qualitative analysis while 14 were in the meta-analysis. The meta-analysis does not support the notion of either the Streitberger or the Park Device being inert control interventions while none of the studies involving the Takakura Device was included in the meta-analysis. Sixteen studies reported the occurrence of adverse events, with no significant difference between verum and placebo acupuncture. Author-reported blinding credibility showed that participant blinding was successful in most cases; however, when blinding index was calculated, only one study, which utilised the Park Device, seemed to have an ideal blinding scenario. Although the blinding index could not be calculated for the Takakura Device, it was the only device reported to enable practitioner blinding. There are limitations with each of the placebo devices and more rigorous studies are needed to further evaluate their effects and blinding credibility.

Buckling-induced retraction of spherical shells: A study on the shape of aperture

Buckling of soft matter is ubiquitous in nature and has attracted increasing interest recently. This paper studies the retractile behaviors of a spherical shell perforated by sophisticated apertures, attributed to the buckling-induced large deformation. The buckling patterns observed in experiments were reproduced in computational modeling by imposing velocity-controlled loads and eigenmode-affine geometric imperfection. It was found that the buckling behaviors were topologically sensitive with respect to the shape of dimple (aperture). The shell with rounded-square apertures had the maximal volume retraction ratio as well as the lowest energy consumption. An effective experimental procedure was established and the simulation results were validated in this study.

Relationship between buckling of acupuncture needles and the handle type

BACKGROUND

Most popular single-use acupuncture needles consist of a stainless steel shaft with a handle made of copper coil or plastic stick.

OBJECTIVES

To determine the strengths and weaknesses of these two handle types for needle buckling.

METHODS

The buckling load for acupuncture needles with these two different handle types was determined using a digital scale, and the stiffness of stainless steel wires used in different types of acupuncture needles was measured using a Dynamic Mechanical Analysis machine.

RESULTS

This study showed that an acupuncture needle with a copper coil handle was far more susceptible to buckling than a needle with a plastic stick handle. The average buckling force of acupuncture needles with plastic stick handles was 46.7% higher than that with copper coil handles for needles of 0.25 mm×30 mm, and 30.8% higher for needles of 0.25 mm×60 mm. Replacing a copper coil handle with a plastic stick handle could save about 100 tonnes of copper wires and 20 million metres of medical grade stainless steel wire a year worldwide.

CONCLUSIONS

The results from this study suggest that the common practice of using coiled copper for handles on acupuncture needles should be re-evaluated. Replacing a copper coil handle with a plastic stick handle would significantly reduce needle buckling and improve patient comfort and safety. This would also reduce the consumption of copper and medical grade stainless steel wire considerably.

Design of fishnet metamaterials with broadband negative refractive index in the visible spectrum

We propose a technique capable of designing fishnet metamaterials that have a negative refractive index (NRI) over a broad range in the visible and infrared. The technique relies on optimizing the shape and scale of the fishnet apertures as well as the depth of different layers of the composite. A metamaterial is obtained that exhibits an unbroken 552 nm bandwidth of NRI, covering the entire red and infrared regions. Moreover, two fishnet structures perforated with star-like holes are found to render refractive index negative in the yellow and green spectra.

Examination of surface conditions and other physical properties of commonly used stainless steel acupuncture needles

OBJECTIVES

The present work examined the surface conditions and various other physical properties of sterilised single-use stainless steel acupuncture needles from two of the most popular brands widely used in many countries.

METHODS

Scanning electron microscope (SEM) images were taken for 10 randomly chosen needles from each brand. Further SEM images were taken after each of these needles underwent a standard manipulation with an acupuncture needling practice gel. A comparison of forces and torques during the needling process was also carried out.

RESULTS

The SEM images revealed significant surface irregularities and inconsistencies at the needle tips, especially for needles from one of the two brands. Metallic lumps and small, loosely attached pieces of material were observed on the surfaces of some needles. Some of the lumps and pieces of material seen on the needle surfaces disappeared after the acupuncture manipulation. If these needles had been used on patients, the metallic lumps and small pieces of material could have been deposited in human tissues, which could have caused adverse events such as dermatitis. Malformed needle tips might also cause other adverse effects including bleeding, haematoma/bruising, or strong pain during needling. An off-centre needle tip could result in the needle altering its direction during insertion and consequently failing to reach the intended acupuncture point or damaging adjacent tissues.

CONCLUSIONS

These findings highlight the need for improved quality control of acupuncture needles, with a view to further enhancing the safety and comfort of acupuncture users.

A study of shape optimization on the metallic nanoparticles for thin-film solar cells

The shape of metallic nanoparticles used to enhance the performance of thin-film solar cells is described by Gielis' superformula and optimized by an evolutionary algorithm. As a result, we have found a lens-like nanoparticle capable of improving the short circuit current density to 19.93 mA/cm2. Compared with a two-scale nanospherical configuration recently reported to synthesize the merits of large and small spheres into a single structure, the optimized nanoparticle enables the solar cell to achieve a further 7.75% improvement in the current density and is much more fabrication friendly due to its simple shape and tolerance to geometrical distortions.

Optimizing two-level hierarchical particles for thin-film solar cells

For the thin-film solar cells embedded with nanostructures at their rear dielectric layer, the shape and location of the nanostructures are crucial for higher conversion efficiency. A novel two-level hierarchical nanostructure (a sphere evenly covered with half truncated smaller spheres) can facilitate stronger intensity and wider scattering angles due to the coexistence of the merits of the nanospheres in two scales. We show in this article that the evolutionary algorithm allows for obtaining the optimal parameters of this two-scale nanostructure in terms of the maximization of the short circuit current density. In comparison with the thin-film solar cells with convex and flat metal back, whose parameters are optimized singly, the short circuit current density is improved by 7.48% and 10.23%, respectively. The exploration of such a two-level hierarchical nanostructure within an optimization framework signifies a new domain of study and allows to better identify the role of sophisticated shape in light trapping in the absorbing film, which is believed to be the main reason for the enhancement of short circuit current density.

Variable selection using the optimal ROC curve: an application to a traditional Chinese medicine study on osteoporosis disease

In biomedical studies, there are multiple sources of information available of which only a small number of them are associated with the diseases. It is of importance to select and combine these factors that are associated with the disease in order to predict the disease status of a new subject. The receiving operating characteristic (ROC) technique has been widely used in disease classification, and the classification accuracy can be measured with area under the ROC curve (AUC). In this article, we combine recent variable selection methods with AUC methods to optimize diagnostic accuracy of multiple risk factors. We first describe one new and some recent AUC-based methods for effectively combining multiple risk factors for disease classification. We then apply them to analyze the data from a new clinical study, investigating whether a combination of traditional Chinese medicine symptoms and standard Western medicine risk factors can increase discriminative accuracy in diagnosing osteoporosis (OP). Based on the results, we conclude that we can make a better diagnosis of primary OP by combining traditional Chinese medicine symptoms with Western medicine risk factors.

In Vitro Hepatic Differentiation of Mesenchymal Stem Cells from Human Fetal Bone Marrow

We examined whether human fetal mesenchymal stem cells (FMSCs) derived from fetal bone marrow were able to differentiate into functional hepatocyte-like cells in vitro The surface phenotype of FMSCs was characterized by flow cytometry. To induce hepatic differentiation of FMSCs, we added hepatocyte growth factor, basic fibroblast growth factor and oncostatin M into the cell culture medium. After 21 days of hepatocyte induction, FMSCs expressed the hepatocyte-specific markers, α-fetoprotein and cytokeratin 18, as demonstrated by immunofluorescence staining. Differentiated FMSCs also demonstrated in vitro functions characteristic of liver cells, including albumin production, urea secretion and glycogen storage. In conclusion, fetal bone marrow-derived FMSCs are able to differentiate into functional hepatocyte-like cells and may serve as a source of cells for liver disease therapy.

Photorealistic virtual anatomy based on Chinese Visible Human data

Virtual reality based learning of human anatomy is feasible when a database of 3D organ models is available for the learner to explore, visualize, and dissect in virtual space interactively. In this article, we present our latest work on photorealistic virtual anatomy applications based on the Chinese Visible Human (CVH) data. We have focused on the development of state-of-the-art virtual environments that feature interactive photo-realistic visualization and dissection of virtual anatomical models constructed from ultra-high resolution CVH datasets. We also outline our latest progress in applying these highly accurate virtual and functional organ models to generate realistic look and feel to advanced surgical simulators.

Role of fascin in the proliferation and invasiveness of esophageal carcinoma cells

Fascin, an actin-bundling protein, induces membrane protrusions and increases cell motility in various transformed cells. The overexpression of fascin in esophageal squamous cell carcinoma (ESCC) has been described only recently, but the roles and mechanism still remained unclear. Here, by using RNA interference (RNAi), we have stably silenced the expression of the fascin in EC109 cells, an ESCC cell line. Down-regulation of fascin resulted in a suppression of cell proliferation and as well as a decrease in cell invasiveness. Furthermore, we revealed that fascin might have functions in regulating tumor growth in vivo. The effect of fascin on cell invasiveness correlated with the activation of matrix metalloproteases such as MMP-2 and MMP-9. We examined that fascin down-expression also led to a decrease of c-erbB-2 and beta-catenin at the protein level. These results suggested that fascin might play crucial roles in regulating neoplasm progression of ESCC.

Effect of dietary supplemental levels of vitamin A on the egg production and immune responses of heat-stressed laying hens

Two experiments were conducted to evaluate the effect of vitamin A supplementation of a commercial layer diet on the laying performance and immune function of heat-stressed hens. In Experiment 1, two different levels of vitamin A supplementation (3,000 and 9,000 IU/kg) were used to investigate the laying performance and antibody titer against Newcastle disease virus (NDV) of heat-stressed hens. Results showed that the high level of vitamin A supplementation (9,000 IU/kg) had a beneficial effect on the feed intake and laying rate of heat-stressed hens (P < 0.05), compared with the control group (3,000 IU/kg). The antibody titers were not influenced by the level of vitamin A (P > 0.05). In Experiment 2, the effect of four levels of vitamin A (3,000, 6,000, 9,000, and 12,000 IU/kg) on the antibody titer to NDV and T lymphocyte proportion was studied. The experimental birds were exposed to a high temperature (31.5 C) 15 d after NDV vaccination (Treatment 1) or immediately (Treatment 2). The results showed that the egg weight was increased (P < 0.01) by the high levels of vitamin A supplementation (6,000 and 9,000 IU/kg), but feed intake, laying rate, and body weight loss were not (P > 0.05). In Treatment 1, vitamin A had no significant effect on antibody titers against NDV in normal or hot environments but increased (P < 0.01) the proportion of alpha-naphthyl acetate esterase (ANAE)-positive cells. Vitamin A supplementation had a significant effect on NDV antibody titer and ANAE-positive cell proportion in Treatment 2 (P < 0.01). The results of the present study suggested that vitamin A supplementation in commercial layer diets to layer chickens under heat stress was beneficial to laying performance and immune function.

[Effect of huancongdan capsule on lipoprotein, apolipoprotein and serum immunoglobulin in vascular dementia patients]

OBJECTIVE

To probe into the effect of Huancongdan capsule (HCDC) on the vascular dementia (VD) related factors, including lipoprotein, apolipoprotein (apo) and serum immunoglobulin.

METHODS

Fifty-two patients of VD were divided into the HCDC group (27 patients, treated with HCDC) and the control group (25 patients, treated with Naofukang). Changes of related parameters were observed.

RESULTS

The effects in lowering triglyceride and total cholesterol and elevating high density lipoprotein cholesterol in the HCDC group were superior to those in the control group (P < 0.01 or P < 0.05), but the effect in lowering low density lipoprotein cholesterol was similar in the two groups (P > 0.05). Compared with data before treatment, in the HCDC group after treatment, the levels of serum apoA1 increased, and serum apoB100, IgA, IgG and circulating immune complex decreased significantly (P < 0.05 or P < 0.01), but the change of apoE level was insignificant (P > 0.05).

CONCLUSION

Through adjusting lipid metabolism, HCDC could improve blood rheologic characteristics, promote cerebral blood flow, improve the oxygen carrying capacity of blood to prevent and treat VD. One of its mechanisms is increasing apoA1 and decreasing apoB100 levels, preventing and improving atherosclerosis and reducing damage of vascular endothelial cells, the another may be its action in improving immune function.

Inhibiting effect of antisense oligonucleotides phosphorthioate on gene expression of TIMP-1 in rat liver fibrosis

AIM

To observe the inhibition of antisense oligonucleotides (asON) phosphorthioate to the tissue inhibitors metalloproteinase-1 (TIMP-1) gene and protein expression in the liver tissue of immunologically induced hepatic fibrosis rats. The possibility of reversing hepatic fibrosis through gene therapy was observed.

METHODS

Human serum albumin (HSA) was used to attack rats, as hepatic fibrosis model, in which asONs were used to block the gene and protein expressing TIMP-1. According to the analysis of modulator, structure protein, coding series of TIMP-1 genome, we designed four different asONs. These asONs were injected into the hepatic fibrosis models through coccygeal vein. The results was observed by RT-PCR for measuring TIMP-1 mRNA expression, immunohistochemistry and in situ hybridization for collagen I, II, special staining of collagen fiber, and electron microscopic examination.

RESULTS

Hepatic fibrosis could last within 363 days in our modified model. The expressing level of TIMP-1 was high during hepatic fibrosis process. It has been proved by the immunohistochemical and the electron microscopic examination that the asON phosphorthioate of TIMP-1 could exactly express in vivo. The effect of colchicine was demonstrated to inhibit the expressing level of mRNA and the content of collagen I, III in the liver of experimental hepatic fibrosis rats. However, the electron microscopy research and the pathologic grading of hepatic fibrosis showed that there was no significant difference between the treatment group and the model group (P> 0.05).

CONCLUSION

The experimental rat model of hepatic fibrosis is one of the preferable models to estimate the curative effect of anti-hepatic fibrosis drugs. The asON phosphorthioate of TIMP-1 could block the gene and protein expression of TIMP-1 in the liver of experimental hepatic fibrosis rats at the mRNA level. It is possible to reverse hepatic fibrosis, and it is expected to study a new drug of antihepatic fibrosis on the genetic level. Colchicine has very limited therapeutic effect on hepatic fibrosis, furthermore, its toxicity and side effects are obvious.

The presence of human immunodeficiency virus type 1 Vpr correlates with a decrease in the frequency of mutations in a plasmid shuttle vector

The human immunodeficiency virus type 1 (HIV-1) Vpr protein induces cell cycle arrest at the border of G(2) and M similar to the arrest caused by agents which damage DNA. We determined whether the presence of Vpr would affect the ability of cells to repair DNA. We developed a shuttle vector system to analyze the effect of Vpr upon the repair of UV-damaged DNA. Our results demonstrated that the presence of Vpr decreased the rate of deletions in this system. Of note, cells arrested in G(2) by other genotoxic agents also increased the frequency of DNA repair of UV-damaged shuttle vectors. We did not observe any direct effect of Vpr upon the rate of double-strand break repair and/or nucleotide excision repair of genomic DNA in cells. Our results suggest a role for HIV-1 Vpr in altering the frequency of DNA repair, a property which may have importance for HIV-1 replication and pathogenesis.

Human immunodeficiency virus type 1 Vpr interacts with HHR23A, a cellular protein implicated in nucleotide excision DNA repair

The human immunodeficiency virus type 1 (HIV-1) vpr gene is an evolutionarily conserved gene among the primate lentiviruses HIV-1, HIV-2, and simian immunodeficiency viruses. One of the unique functions attributed to the vpr gene product is the arrest of cells in the G2 phase of the cell cycle. Here we demonstrate that Vpr interacts physically with HHR23A, one member of an evolutionarily conserved gene family involved in nucleotide excision repair. Interaction of Vpr with HHR23A was initially identified through a yeast two-hybrid screen and was confirmed by the demonstration of direct binding between bacterially expressed recombinant and transiently expressed or chemically synthesized protein products. Visualization of HHR23A and Vpr by indirect immunofluorescence and confocal microscopy indicates that the two proteins colocalize at or about the nuclear membrane. We also map the Vpr-binding domain in HHR23A to a C-terminal 45-amino-acid region of the protein previously shown to have homology to members of the ubiquitination pathway. Overexpression of HHR23A and a truncated derivative which includes the Vpr-binding domain results in a partial alleviation of the G2 arrest induced by Vpr, suggesting that the interaction between Vpr and HHR23A is critical for cell cycle arrest induced by Vpr. These results provide further support for the hypothesis that Vpr interferes with the normal function of a protein or proteins involved in the DNA repair process and, thus, in the transmission of signals that allow cells to transit from the G2 to the M phase of the cell cycle.

[Clinical study of bugu shengsui capsule in treating primary osteoporosis with kidney-yang deficiency syndrome]

OBJECTIVE

To assess the effect of Bugu Shengsui capsule (BGSSC) in treating primary osteoporosis.

METHODS

Using double energy X-ray bone densimeter and radioimmunoassay (RIA), the effect of BGSSC in treating primary osteoporosis (OP) with Kidney-Yang Deficiency syndrome.

RESULTS

The clinical markedly effective and total effective rates of BGSSC were 46% and 82%, respectively. The rate of TCM group is significantly higher than that of the control group (Vitamin D plus calcium). BGSSC could improve bone mineral density by the verification of double energy X-ray bone dansity (DEXA). It could also increase the level of serum calcitonin, luteinizing hormone and calcium, decrease the activity of parathyroid hormone.

CONCLUSIONS

The effects of BGSSC on primary OP included increasing patient's bone mineral density, depressing bone resorption and decreasing bone loss.

Synthetic NGF peptide derivatives prevent neuronal death via a p75 receptor-dependent mechanism

Cyclized peptides corresponding to beta-loop regions of NGF were purified by HPLC and assayed for neurotrophic activity using DRG neurons. Peptides with the highest activity corresponded to loop region 29-35, a domain likely to interact with the p75 receptor. Unexpectedly, activity was confined to late-eluting HPLC fractions containing peptide multimers and primarily promoted neuronal survival without neurite outgrowth. Directed synthesis of dimer and monomer cyclized peptides demonstrated that dimers acted as partial NGF agonists in that they had both survival-promoting and NGF-inhibiting activity while monomer and linear peptides were inactive. Dimer activity was not affected by the Trk inhibitor K252a but was blocked by p75 receptor antibody and absent using p75 null mutant neurons. These studies suggest that region 29-35 peptide derivatives inhibit neuronal death via a structure- and p75-dependent mechanism.

Optical folding-flash analog-to-digital converter with analog encoding

We describe an optically assisted folding-flash analog-to-digital converter. The periodic transfer function of the Mach-Zehnder interferometer is used to perform analog folding on the electronic signal to be quantized. A novel analog encoding scheme for efficient generation of gray code digital data is proposed. The new encoding scheme eliminates the requirement for interferometers with ultralow V(pi), which, so far, has hindered the development of such systems. The encoding concept is experimentally demonstrated through the use of LiNbO(3) modulators.

[Clinical and laboratory studies of effect of longevity-antihypertensive-mixture on elderly hypertension with kidney deficiency]

Longevity-Antihypertensive-Mixture (LAM) is a Chinese herbal drug, which could tonify Kidney in treating the hypertension with Kidney Deficiency in aged patients.

RESULTS

302 patients were randomly divided into three group: The treated group was subdivided into group I (107 Kidney Yin Deficiency patients) and group II (96 non-Kidney Yin Deficiency cases) and group III (99, control group). After treatment of LAM for 8 weeks, the rate of normalizing the blood pressure was 92.52% in group I while in group II, it was 84.43%, the symptoms were also significantly alleviated, and in group III, the rate was 70.71% only. The aorta compliance in group I significantly improved after LAM treatment (P < 0.025), the quality index of left ventricle reduced in treated group, and there was significant difference between treated and control groups. After treatment, LAM could shorten the length of extracorporal thrombus in group. The study showed that LAM could treat hypertension through LAM, administration with good effect.

The Rex proteins of human T-cell leukemia virus type II differ by serine phosphorylation

The Rex proteins of human T-cell leukemia virus types I and II (HTLV-I and HTLV-II) induce cytoplasmic expression of unspliced gag-pol mRNA and singly spliced env mRNA and are critical for virus replication. Two rex gene products, p27rex and p21rex of HTLV-I and p26rex and p24rex of HTLV-II, have been detected in HTLV-infected cells; however, the structural and biological relationship of the proteins has not been clearly elucidated. Endoproteinase digestion and phosphoamino acid analysis of HTLV-II Rex indicated that p24rex has the same amino acid backbone as p26rex and that the larger apparent molecular size of p26rex is attributable to serine phosphorylation.