A Systematic Study of the Factors Affecting the Surface Quality of Chemically Vapor-Deposited Diamond during Chemical and Mechanical Polishing.

Diamond surfaces must be of high quality for potential use in semiconductors, optical windows, and heat conductivity applications. However, due to the material's exceptional hardness and chemical stability, it can be difficult to obtain a smooth surface on diamond. This study examines the parameters that can potentially influence the surface quality of chemically vapor-deposited (CVD) diamonds during the chemical and mechanical polishing (CMP) process. Analysis and experimental findings show that the surface quality of polished CVD diamonds is significantly influenced by the crystal structure and the growth quality of the diamond. In particular, when the surface roughness is below Ra 20 nm, the pores and grain boundaries on CVD diamond obstruct surface roughness reduction during mechanical polishing. To obtain a smooth polished surface, careful consideration of the size of diamond abrasives and polishing methods is also a prerequisite. Chemical mechanical polishing is a novel method to achieve a surface quality with roughness below Ra 3 nm, as in this method, the anisotropy of the CVD diamond allows the uneven steps to be efficiently erased. However, the chemical actions of polishing slurry should be controlled to prevent the formation of chemical etching pits.

High-precision 3D printing of multi-branch vascular scaffold with plasticized PLCL thermoplastic elastomer.

Three-dimensional (3D) printing has emerged as a transformative technology for tissue engineering, enabling the production of structures that closely emulate the intricate architecture and mechanical properties of native biological tissues. However, the fabrication of complex microstructures with high accuracy using biocompatible, degradable thermoplastic elastomers poses significant technical obstacles. This is primarily due to the inherent soft-matter nature of such materials, which complicates real-time control of micro-squeezing, resulting in low fidelity or even failure. In this study, we employ Poly (L-lactide-co-ϵ-caprolactone) (PLCL) as a model material and introduce a novel framework for high-precision 3D printing based on the material plasticization process. This approach significantly enhances the dynamic responsiveness of the start-stop transition during printing, thereby reducing harmful errors by up to 93%. Leveraging this enhanced material, we have efficiently fabricated arrays of multi-branched vascular scaffolds that exhibit exceptional morphological fidelity and possess elastic moduli that faithfully approximate the physiological modulus spectrum of native blood vessels, ranging from 2.5 to 45 MPa. The methodology we propose for the compatibilization and modification of elastomeric materials addresses the challenge of real-time precision control, representing a significant advancement in the domain of melt polymer 3D printing. This innovation holds considerable promise for the creation of detailed multi-branch vascular scaffolds and other sophisticated organotypic structures critical to advancing tissue engineering and regenerative medicine.

Investigation on an Innovative Method for High-Speed Low-Damage Micro-Cutting of CFRP Composites with Diamond Dicing Blades.

This paper presents an innovative method for high-speed micro-cutting of carbon fiber reinforced plastics (CFRP). It employs a diamond dicing blade for micromachining applications, with a thickness of about 200 µm and rotational speeds up to 30,000 rpm so as to meet the low-damage surface integrity requirements. The process parameters, cutting damage, surface roughness, and the spindle vibration were thoroughly investigated to evaluate and validate the method. The results indicate that a high cutting speed up to 76 m/s not only remarkably increases the rigidity of an ultra-thin dicing blade, but also decreases the cutting depth per diamond grit to below 10 nm, both of which are very conducive to obtaining a very fine machined surface of about Ra 0.025 µm, with no obvious damage, such as delamination, burrs, and fiber pull out. The serious spindle vibration limits the rotational speed to increase further, and the rotational speed of 25,000 rpm achieves the best fine machined surface. Furthermore, unlike most research results of the drilling and milling method, the proposed micro-cutting method obtains the maximum cutting current and surface roughness when cutting at 0° fiber orientation, while obtaining a minimum cutting current and surface roughness when cutting at 90° fiber orientation. The metal-bonded dicing blade achieves smaller surface roughness than the resin-bonded dicing blade. This paper also discusses the cutting mechanism by investigating the morphology of the machined surface and concludes that the micro breakage and plastic-flow in local regions of fibers and resin are the main material removal mechanisms for dicing CFRP composites with a diamond abrasive blade.

Prognostic value of circulating tumor cells detected with the CellSearch System in patients with gastric cancer: evidence from a meta-analysis.

BACKGROUND: Circulating tumor cells (CTCs) have been proposed as a marker for predicting the prognosis of cancer. However, the prognostic value of CTCs detected with the CellSearch System in patients with gastric cancer (GC) remains controversial. We performed a meta-analysis of available studies to investigate this topic. METHODS: Two authors systematically searched the studies independently in PubMed, Science Citation Index, Cochrane Database, Embase, and the references in relevant studies (up to September 2017) using keywords. Our meta-analysis was performed in Stata software, version 12.0 (2011; Stata Corp, College Station, TX, USA), with the risk ratio (RR), hazard ratio (HR), and 95% CI as the effect measures. Subgroup analyses and meta-regression were also conducted. RESULTS: Seven studies (including eight sets of data) containing 579 patients with GC from four countries were included in this meta-analysis. The pooled results showed CTC-positive status detected by the CellSearch System was significantly associated with poor overall survival (HR =2.09, 95% CI [1.71, 2.55], P<0.001, I2=31.5%) and progression-free survival (HR =2.11, 95% CI [1.25, 3.57], P=0.005, I2=75.6%) of patients with GC, regardless of sampling time. The disease control rate of CTC-positive group was lower than that of CTC-negative group for both baseline and intra-therapy, although no statistical difference existed at both sampling time points (baseline: 69.5% versus 81.8%, RR=0.79, 95% CI [0.54, 1.16], P=0.23, I2=68.0%; intra-therapy: 50.0% versus 85.9%, RR=0.24, 95% CI [0.02, 3.13], P=0.28, I2=87.4%). CONCLUSION: Our meta-analysis demonstrated that CTCs detected with the CellSearch System from the peripheral blood had significant prognostic value and might predict poor response to chemotherapy for patients with GC.

Prognostic and clinicopathological significance of microRNA-494 overexpression in cancers: a meta-analysis.

MicroRNA-494 was revealed as an attractive prognostic biomarker in recent studies. Nevertheless, the prognostic value of microRNA-494 in cancers remains controversial. Current meta-analysis aims to elucidate the precise predictive value of microRNA-494 in various cancers. Eligible studies were identified through multiple search strategies, the hazard ratios (HRs) and their confidence interval (CI) for patient prognostic outcomes were extracted and estimated. The pooled results of fifteen studies indicated that elevated expression of microRNA-494 implies a good overall survival of cancer patients (HR = 0.58, 95% CI: 0.36-0.91); While no significant association was found between the high expression of microRNA-494 and clinicopathological characteristic. Additionally, subgroup analysis revealed that overexpression of microRNA-494 predicted a worse overall survival in non-small cell lung cancer (HR = 2.35, 95% CI: 1.05-5.24) and colorectal cancer (HR = 2.59, 95% CI: 1.62-4.14). As per the subgroup analysis, the cancer type, the anatomy system classification and the ethnic background had influence on the overall survival result. Our findings indicate that elevated expression of microRNA-494 might predict a good overall survival in most cancers, while in non-small cell lung cancer and colorectal cancer, overexpression of microRNA-494 might predict a worse overall survival.

Clinicopathological and prognostic significance of circulating tumor cells in patients with head and neck cancer: a meta-analysis.

BACKGROUND: Many studies have assessed the clinical use of circulating tumor cells (CTCs) in head and neck cancer, but the clinicopathological and prognostic significance of CTCs is still unclear. MATERIALS AND METHODS: Two authors systematically searched the studies independently with keywords in PubMed, MEDLINE, EMBASE, Science Citation Index Expanded and Cochrane Library (from inception to February 2017). The estimated hazard ratio (HR), risk ratio (RR) and their 95% confidence intervals (95% CIs) were set as effect measures. All analyses were performed by STATA 12.0. RESULTS: A total of 17 studies were included in this meta-analysis. Positive CTCs were significantly associated with poor overall survival (HR =2.80, 95% CI: 1.34-5.86), disease-free survival (HR =3.86, 95% CI: 2.03-7.36) and progression-free survival (HR =3.31, 95% CI: 1.71-6.42). CTC-positive patients tend to have higher recurrence (RR =2.13, 95% CI: 1.26-3.59) and regional lymph node metastasis (RR =1.18, 95% CI: 1.02-1.36) rate and a more advanced tumor stage (RR =1.16, 95% CI: 1.03-1.32). CONCLUSION: Our meta-analysis has confirmed the significant prognostic value of CTCs in head and neck cancer patients. The presence of CTCs could be used as a monitoring tool for tumor status of head and neck cancer, especially for the early detection of the tumor recurrence and progression, advanced disease and the node metastasis.