No abstract

We describe a scheme to generate the ground-state network for carbon clusters. Combining ' it is reported that structures for Cs2 and Cs4 always contain seven-member ring defects although we now know that a much more stable structure exists with only five-and six-membered rings. The energy to break the carbon bonds and rearrange the network is so high that it is difficult to reach the ground state unless one starts from a structure which already has the correct topology.To overcome the difficulties mentioned above, we devised a scheme for generating energetically favorable structures for large fullerenes. In this scheme, we first focus on generating the correct topological networks for energetically favorable structures. Instead of looking at the network connecting individual atoms, we focus our attention on the "face-dual" network obtained by linking the centers of each of the polygonal face of the cage structure. Since each atom of the fullerene is threefold coordinated, the face-dual network consists of a triangular mesh. For a fullerene with N atoms, the number of polygonal faces is N/2+2. We represent each of the faces by a point lying on a predetermined surface (a sphere for example) and obtain the ground-state network by simulated annealing. Initially these points are placed at random and interact with one another through a two-body repulsive potential. The face-dual network obtained can then be inverted to obtain the fullerene structure. In this scheme, whether a face is pentagonal or hexagonal is determined by the number of nearest-neighboring faces. Thus the change from pentagon to hexagon can occur easily with a small energy barrier and even for quite large number of atoms, the system does not get trapped in local metastable states. Also, this scheme distributes the faces as evenly as possible on the constrained surface and the resultant topological networks tend to separate the pentagonal faces as far apart as possible which makes the structures generated good candidates for low-energy fullerene structures. By varying the shape of the constraining surface (changing 7333

A polyacrylamide gel (PAG) containing bovine serum albumin (BSA) is introduced as a new tissue-mimicking phantom for the purpose of visualizing three-dimensional coagulation temperature distribution during radiofrequency ablation (RFA). The coagulation temperature of the phantom can be changed at the same range of biological tissue (50-60 degrees C) by adjusting the pH from 4.3 to 4.7. The phantom is transparent except in thermal coagulation regions which are ivory white. The physical properties of the phantom, such as density, electrical conductivity and specific heat capacity, are very favorable, similar to those of soft tissues. We illustrate the usefulness of the phantom in visualizing RFA lesions. This phantom has magnetic resonance properties which change drastically upon thermal coagulation, enabling its use for the characterization of RFA device, quality assurance, treatment planning and treatment verification. The PAG containing BSA, whose pH was adjusted from 4.3 to 4.7, is an attractive tissue-mimicking phantom suitable for RFA investigations.

Background Appendicitis is the most common abdominal surgical emergency worldwide, and its burden has been changing. We report the level and trends of appendicitis prevalence, and incidence; and years lived with disability (YLD) in 204 countries and territories from 1990 to 2019, based on data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019. Methods The numbers and age-standardized prevalence, incidence, and YLD rates per 100,000 population of appendicitis were estimated across regions and countries by age, sex, and sociodemographic index (SDI). All the estimates were reported with 95% uncertainty intervals (UIs). Results Globally, the age-standardized prevalence and incidence rates of appendicitis in 2019 were 8.7 (95% UI 6.9 to 11.0) and 229.9 (95% UI 180.9 to 291.0) per 100,000 population, with increases of 20.8% (95% UI 18.9 to 23.0%) and 20.5% (95% UI 18.7 to 22.8%) from 1990 to 2019, respectively. Additionally, the age-standardized YLDs rate was 2.7 (95% UI 1.8 to 3.9) in 2019, with an increase of 20.4% (95% UI 16.2 to 25.1%) from 1990 to 2019. In 2019, the age-standardized prevalence, incidence, and YLD rates peaked in the 15-to-19-year age groups in both male and female individuals. However, no statistically significant differences were observed between the male and female individuals in all groups. Ethiopia, India, and Nigeria showed the largest increases in the age-standardized prevalence rate between 1990 and 2019. Generally, positive associations were found between the age-standardized YLD rates and SDI at the regional and national levels. Conclusions Appendicitis remains a major public health challenge globally. Increasing awareness of appendicitis and its risk factors and the importance of early diagnosis and treatment is warranted to reduce its the burden.

No abstract

The incidence of malignant bone tumor increases every year. Because the application of high-intensity focused ultrasound (HIFU) for the treatment of bone tumors is still at a nascent stage, it is essential to study the effectiveness of this technique in ideal animal models in order to obtain a beneficial reference for imaging studies. In this study, we established a VX2 malignant bone tumor model and evaluated this model by contrast-enhanced sonography and magnetic resonance imaging (MRI). The results show that all tumors were enhanced after injection of SonoVue. A contrast-enhanced MRI scan revealed obvious enhancement within the tumors. Histological examination revealed the presence of a large number of tumor cells. The model can serve as an ideal experimental model for the study of HIFU therapy in the treatment of malignant bone tumors and as a reference for imaging studies during follow-ups.

Combination of ultrasonic studies on the hepatic hemodynamics with the evaluation of serum HA may provide an indicator for hepatic fibrosis in patients with IHS. This may be a useful noninvasive method for the diagnosis and evaluation of the prognosis of IHS.

Our results indicate that HIFU appears to be an effective therapy for ovarian carcinoma tumours in the athymic nude mouse model. We suggest that it may hold promise for the clinical treatment of late-stage and recurrent ovarian cancer.