摩托车整车噪声分析与消声器改进

基于噪声声压、声强测试,分析声压频谱、声强与声功率分布,识别某摩托车噪声源,结果表明,发动机缸头处与排气管处对整车噪声贡献相当,考虑优化成本和改进的复杂程度,主要针对排气消声器改进。利用有限元仿真手段和试验对原发动机排气消声器空气动力学性能和声学性能进行了研究,提出了消声器改进方案,通过消声器功率损失测试、插入损失测试和整车通过噪声实验,结果表明,改进方案使整车通过噪声降低1-2dB。     

Uncertainty budget for a whole body counter in the scan geometry and computer simulation of the calibration phantoms

At the Austrian Research Centers Seibersdorf (ARCS), a whole body counter (WBC) in the scan geometry is used to perform routine measurements for the determination of radioactive intake of workers. The calibration of the WBC is made using bottle phantoms with a homogeneous activity distribution. The same calibration procedures have been simulated using Monte Carlo N-Particle (MCNP) code and FLUKA and the results of the full energy peak efficiencies for eight energies and five phantoms have been compared with the experimental results. The deviation between experiment and simulation results is within 10%. Furthermore, uncertainty budget evaluations have been performed to find out which parameters make substantial contributions to these differences. Therefore, statistical errors of the Monte Carlo simulation, uncertainties in the cross section tables and differences due to geometrical considerations have been taken into account. Comparisons between these results and the one with inhomogeneous distribution, for which the activity is concentrated only in certain parts of the body (such as head, lung, arms and legs), have been performed. The maximum deviation of 43% from the homogeneous case has been found when the activity is concentrated on the arms.     

Mapping institutions and their weak ties in a specialty: A case study of cystic fibrosis body composition research

The paper demonstrates visualization technique that show the collaboration structure of institutions in the specialty and the researchers that function as weak ties among them. Institution names were extracted from the collection of papers and disambiguated using the Derwent Analytics (v1.2) software product. Institutions were clustered into collaboration groups based on their co-occurrence in papers. A crossmap of clustered institutions against research fronts, which were derived using bibliographic coupling analysis, shows the research fronts that specific institutions participate in, their collaborator institutions and the research fronts in which those collaborations occurred. A crossmap of institutions to author teams, derived from co-authorship analysis, reveals research teams in the specialty and their general institutional affiliation, and further identifies the researchers that function as weak ties and the institutions that they link. The case study reveals that the techniques introduced in this paper can be used to extract a large amount of useful information about institutions participating in a research specialty.     

Assessment of reinforced poly(ethylene glycol) chitosan hydrogels as dressings in a mouse skin wound defect model

Wound dressings of chitosan are biocompatible, biodegradable, antibacterial and hemostatic biomaterials. However, applications for chitosan are limited due to its poor mechanical properties. Here, we conducted an in vivo mouse angiogenesis study on reinforced poly(ethylene glycol) (PEG)-chitosan (RPC) hydrogels. RPC hydrogels were formed by cross-linking chitosan with PEGs of different molecular weights at various PEG to chitosan ratios in our previous paper. These dressings can keep the wound moist, had good gas exchange capacity, and was capable of absorbing or removing the wound exudate. We examined the ability of these RPC hydrogels and neat chitosan to heal small cuts and full-thickness skin defects on the backs of male Balb/c mice. Histological examination revealed that chitosan suppressed the infiltration of inflammatory cells and accelerated fibroblast proliferation, while PEG enhanced epithelial migration. The RPC hydrogels promoted wound healing in the small cuts and full layer wounds. The optimal RPC hydrogel had a swelling ratio of 100% and a water vapor transmission rate (WVTR) of about 2000 g/m²/day. In addition, they possess good mechanical property and appropriate degradation rates. Thus, the optimal RPC hydrogel formulation functioned effectively as a wound dressing and promoted wound healing.     

Development of nanotechnology for advancement and application in wound healing: a review

Wound healing is a series of different dynamic and complex phenomena. Many studies have been carried out based on the type and severity of wounds. However, to recover wounds faster there are no suitable drugs available, which are highly stable, less expensive as well as has no side effects. Nanomaterials have been proven to be the most promising agent for faster wound healing among all the other wound healing materials. This review briefly discusses the recent developments of wound healing by nanotechnology, their applicability and advantages. Nanomaterials have unique physicochemical, optical, and biological properties. Some of them can be directly applied for wound healing or some of them can be incorporated into scaffolds to create hydrogel matrix or nanocomposites, which promote wound healing through their antimicrobial, as well as selective anti‐ and pro‐inflammatory, and proangiogenic properties. Owing to their high surface area to volume ratio, nanomaterials have not only been used for drug delivery vectors but also can affect wound healing by influencing collagen deposition and realignment and provide approaches for skin tissue regeneration.Inspec keywords: skin, wounds, cellular biophysics, drug delivery systems, tissue engineering, hydrogels, nanocomposites, proteins, nanomedicineOther keywords: wound healing materials, nanomaterials, nanotechnology, proangiogenic properties, proinflammatory properties, collagen deposition, drug delivery vectors, skin tissue regeneration     

Application of new imaging and calculation techniques to activity and dose assessment in the case of a 106Ru contaminated wound

The aim of this paper is to describe the dosimetric evaluation of a point contamination that occurred in a laboratory during the examination of an irradiated sample. The incident led to point contamination of the operator's finger due to the presence of mainly 106Ru, with its progeny, 106Rh. The paper reports on the activity and dose assessment, performed using several methods. The measured activity was obtained using a conventional device based on a germanium detector and confirmed using software developed at IRSN, based on reconstruction of voxel phantom associated with the Monte Carlo N-Particle code (MCNP) for in vivo measurement. Two dose assessment calculations were performed using both analytical and Monte Carlo methods, applying the same approach as for activity assessment based on the personal computational phantom of the finger. The results are compared, followed by a discussion on the suitability of the tools described in this study.     

Analytical applications of cooperative interactions associated with charge transfer in cyanometalate electrodes: analysis of sodium and potassium in human whole blood

Nickel electrodes chemically modified with an interfacial layer of nickel ferrocyanide are shown to be of analytical utility for simultaneously sensing sodium and potassium ions in aqueous solutions, human whole blood serum, and human whole blood. By controlling the charge-transfer characteristics of this versatile interface, interfering blood proteins and potential interferences associated with other alkali cations can be avoided. A solid-state model which explains the excellent simultaneous selectivity and sensitivity of the nickel ferricyanide interface is proposed.     

Optimal movement in the prey strikes of weakly electric fish: a case study of the interplay of body plan and movement capability

Animal behaviour arises through a complex mixture of biomechanical, neuronal, sensory and control constraints. By focusing on a simple, stereotyped movement, the prey capture strike of a weakly electric fish, we show that the trajectory of a strike is one which minimizes effort. Specifically, we model the fish as a rigid ellipsoid moving through a fluid with no viscosity, governed by Kirchhoff's equations. This formulation allows us to exploit methods of discrete mechanics and optimal control to compute idealized fish trajectories that minimize a cost function. We compare these with the measured prey capture strikes of weakly electric fish from a previous study. The fish has certain movement limitations that are not incorporated in the mathematical model, such as not being able to move sideways. Nonetheless, we show quantitatively that the computed least-cost trajectories are remarkably similar to the measured trajectories. Since, in this simplified model, the basic geometry of the idealized fish determines the favourable modes of movement, this suggests a high degree of influence between body shape and movement capability. Simplified minimal models and optimization methods can give significant insight into how body morphology and movement capability are closely attuned in fish locomotion.     

Scholarly publishing in social sciences and humanities, associated probabilities of belonging and its spectrum: a quantitative approach for the Spanish case

In this study, differences between Spanish social sciences and humanities journals are examined using a quantitative approach. Firstly, using a set of 144 psychology journals and 69 philosophy journals, statistically significant differences have been identified in 11 characteristics/indicators. Secondly, a logistic regression was carried out on the dichotomous response variable “belonging to the social sciences” or “belonging to the humanities”, on 777 Spanish social sciences journals, 563 humanities journals that have been previously classified and 17 existing predictor variables. The regression model reached an overall correct classification of 78.8 %. The explanatory variables considered in the model are analyzed and interpreted taking into account the change in the odds ratio and the indication of their contribution to the correct classification rate in the two response values. Finally the average associated probability of belonging to the social sciences group is calculated for each discipline and reflected in a spectrum of the probability of belonging to the social sciences or the humanities.     

Fibrous wound repair associated with biodegradable poly-L/D-lactide copolymer implants: study of the expression of tenascin and cellular fibronectin

Extracellular matrix (ECM) proteins are known to play a role in inflammatory and hyperplastic processes. Our aim in the present study was to study the distribution of tenascin (Tn), cellular fibronectins (cFn) and myofibroblasts around biodegradable poly-L/D-lactide (PLA) implants with monoclonal antibodies (MAb). Ethylene-oxide and gamma-irradiation sterilized PLA plate-type implants were inserted into the dorsal subcutaneous tissue of ten adult rabbits. Follow-up times were 4, 12, 16, 36 and 48 wk. Only some inflammatory cells were observed. In electron microscopy, a close coherence between the implant and the stromal tissue was seen. Immunoreactivity for Tn, cFn and -actin was detected as a distinct layer bordering the implant, regardless of the sterilization method for the first 36 wk. From week 36 onwards, Tn immunoreactivity was downregulated while cFn immunoreactivity still persisted. A moderate upregulation for myofibroblasts was seen on the week 48 specimens, when hydrolysation of PLA implant had started. The persistent content of myofibroblasts, Tn and cFn suggests a prolonged wound healing produced by PLA implants. The absence of Tn at the week 48 specimens suggests that cFn, rather than Tn may be needed for -actin-mediated contraction by myofibroblasts.     

A one-step treatment for chondral and osteochondral knee defects: clinical results of a biomimetic scaffold implantation at 2 years of follow-up

The increasing interest in the role of subchondral bone with regard to articular surface disease led to the development of new bioengineered strategies. Aim of this study is to evaluate the clinical and MRI outcome after the implantation of a nanostructured biomimetic three-phasic collagen–hydroxyapatite construct for the treatment of chondral and osteochondral defects of the knee in a large cohort of patients. Seventy-nine patients (63 M, 16 W), affected by grade III–IV femoral condyle or trochlea chondral lesions or osteochondritis dissecans (OCD) were consecutively treated. Mean age was 31.0 ± 11.3 years, mean lesion size was 3.2 ± 2.0 cm². Fifty patients underwent previous surgeries, concurrent procedures were necessary in 39 cases. The clinical outcome was evaluated using the IKDC and Tegner scores at 12 and 24 months of follow-up. At follow-up times an MRI was performed and evaluated with the MOCART score. All the scores improved significantly from the baseline. IKDC subjective score showed a further increase between 12 and 24 months of follow-up, and 82.2 % of the patients improved their symptoms at the final evaluation. Patients affected by OCDs had better results than those with degenerative lesions. Some abnormal MRI findings were present, even though no correlation was found with the clinical outcome. This one-step biomimetic approach developed to favor osteochondral tissue regeneration is effective in treating knees affected by damages of the articular surface, leading to a significant clinical improvement. However, abnormal MRI findings were present, even if not correlated with the clinical outcome.     

GGSN协议的一个流程问题分析及改进

在网关GPRS(通用无线分组业务)支持节点(GGSN)项目与服务GPRS支持节点(SGSN)项的集成测试中发现了GGSN相关协议的一处流程交互的定义的缺陷,该缺陷导致在异常的流程处理中大量垃圾上下文的生成,并使得GGSN与SGSN两侧信息产生较大的不一致,这些不一致的信息将在较长时间影响系统的后续运行并产生运行错误.本文分析了此流程缺陷产生的原因并对相应流程提出一种改进的方法.实验环境下的测试结果表明,对协议做这样的改进可以完全解决这一问题并保证工程实现的高效性.     

Design and characterization of a chitosan physical gel promoting wound healing in mice

In this study, a sterile and biocompatible chitosan (CHI) gel for wound healing applications was formulated. CHI powder was treated in autoclave (ttCHI) to prepare sterile formulations. The heat treatment modified the CHI molecular weight, as evidenced by GPC analysis, and its physical–chemical features. Differential scanning calorimetry studies indicated that the macromolecules, before and after thermal treatment, differ in the strength of water-polymer interaction leading to different viscoelastic and flow properties. Thermally treated CHI exhibited the following effects: (i) increased the proliferation and migration of human foreskin foetal fibroblasts at 24 h; (ii) accelerated wound healing (measured as area of lesion) at 3 and 10 days in an in vivo model of pressure ulcers. These effects were linked to the increase of the hydroxyproline and haemoglobin content as well as Wnt protein expression. Moreover, we found a reduction of myeloperoxidase activity and TNF-α mRNA expression. These observations suggest the potential of this novel CHI gel in wound healing and other therapeutic applications.     

Partitioning spectral absorption in case 2 waters: discrimination of dissolved and particulate components

A series of three mathematical procedures is derived to discriminate the light absorption by phytoplankton, colored dissolved organic matter, and nonpigmented particulates in waters in which absorption is dominated by factors other than phytoplankton (i.e., case 2 waters). The procedures utilize normalized absorption cross-sectional spectra of the absorption components and matrix inversion to solve for the coefficients that scale the normalized spectra. The procedures differ in the amount of ancillary measurements incorporated to reduce the variability of the estimates. The procedure that incorporates no ancillary information is expected to be unbiased only over long time periods. Application of the procedures to a 15-day time series of continuously monitored data from the Rhode River, Maryland, revealed the presence of large (approximately twofold) changes in absorption at 440 nm over periods of a few hours. Hourly sampling over a 24-h period confirmed that the changes in measured optical coefficients corresponded to changes in water quality. Errors in estimates of absorption components were of a magnitude consistent with those observed in development of the procedures and confirmed the progressive improvement achieved by incorporation of additional information. Over the time period observed, changes in optical properties appeared to be driven by advective processes.     

Penetration,distribution and brain toxicity of titanium nanoparticles in rodents' body: a review

Titanium dioxide (TiO₂) has been vastly used commercially, especially as white pigment in paints, colorants, plastics, coatings, cosmetics. Certain industrial uses TiO₂ in diameter <100 nm. There are three common exposure routes for TiO₂ : (i) inhalation exposure, (ii) exposure via gastrointestinal tract, (iii) dermal exposure. Inhalation and gastrointestinal exposure appear to be the most probable ways of exposure, although nanoparticle (NP) penetration is limited. However, the penetration rate may increase substantially when the tissue is impaired. When TiO₂ NPs migrate into the circulatory system, they can be distributed into all tissues including brain. In brain, TiO₂ lead to oxidative stress mediated by the microglia phagocytic cells which respond to TiO₂ NPs by the production and release of superoxide radicals that convert to multiple reactive oxygen species (ROS). The ROS production may also cause the damage of blood–brain barrier which then becomes more permeable for NPs. Moreover, several studies have showed neuron degradation and the impairment of spatial recognition memory and learning abilities in laboratory rodent exposed to TiO₂ NPs.Inspec keywords: nanoparticles, permeability, health hazards, molecular biophysics, biochemistry, biological tissues, toxicology, oxidation, brain, neurophysiology, blood, reviews, cosmetics, cellular biophysics, titanium compoundsOther keywords: rodents, white pigment, gastrointestinal tract, dermal exposure, gastrointestinal exposure, nanoparticle penetration, penetration rate, blood–brain barrier, titanium nanoparticles, brain toxicity, size 100.0 nm, TiO₂      

Perfusion in microfluidic cross-flow: separation of white blood cells from whole blood and exchange of medium in a continuous flow

We describe a microfluidic technique for separation of particles and cells and a device that employs this technique to separate white blood cells (WBC) from whole human blood. The separation is performed in cross-flow in an array of microchannels with a deep main channel and large number of orthogonal, shallow side channels. As a suspension of particles advances through the main channel, a perfusion flow through the side channels gradually exchanges the medium of the suspension and washes away particles that are sufficiently small to enter the shallow side channels. The microfluidic device is tested with a suspension of polystyrene beads and is shown to efficaciously exchange the carrier medium while retaining all beads. In tests with whole human blood, the device is shown to reduce the content of red blood cells (RBC) by a factor of approximately 4000 with retention of 98% of WBCs. The ratio between WBCs and RBCs reached at an outlet of the device is 2.4 on average. The device is made of a single cast of poly(dimethylsiloxane) sealed with a cover glass and is simple to fabricate. The proposed technique of separation by perfusion in continuous cross-flow could be used to enrich rare populations of cells based on differences in size, shape, and deformability.     

Studies on gelatin-based sponges. Part III: A comparative study of cross-linked gelatin/alginate, gelatin/hyaluronate and chitosan/hyaluronate sponges and their application as a wound dressing in full-thickness skin defect of rat

Novel cross-linked sponges composed of gelatin/alginate and gelatin/hyaluronate and chitosan/hyaluronate (GH, GA and CH, respectively) were prepared and compared. Six different sponges with or without silver sulfadiazine (AgSD) were applied on the full-thickness dorsal skin defect of Wistar rat. The histology and epidermal wound healing rates of the skin defects were investigated by light microscopy and computerized morphometry 5 and 12 days post-operatively. In our full-thickness wound model (diameter 1 cm), the AgSD-impregnated sponges showed good wound healing performances on the whole. However, there appeared meaningful differences of wound healing between the gelatin-based sponges (GH, GA) and the CH. GH with AgSD was found to show the best wound healing properties as a wound dressing resulting from histological findings and computerized morphometric analysis of epidermal healing.     

Synthesis and characterization of 3D topological insulators: a case TlBi(S1?xSex)2

In this article, practical methods for synthesizing Tl-based ternary III-V-VI₂ chalcogenide TlBi(SSe_x)₂ are described in detail, along with characterization by x-ray diffraction and charge transport properties. The TlBi(SSe_x)₂ system is interesting because it shows a topological phase transition, where a topologically nontrivial phase changes to a trivial phase without changing the crystal structure qualitatively. In addition, Dirac semimetals whose bulk band structure shows a Dirac-like dispersion are considered to exist near the topological phase transition. The technique shown here is also generally applicable for other chalcogenide topological insulators, and will be useful for studying topological insulators and related materials.