This paper presents an analytical approach to investigating the chip formation process in micro-milling aluminum 6082-T6 particularly by using natural diamond and tungsten carbide tools. Through well-designed micro-milling experiments, a comparative study is conducted by utilizing a natural diamond tool with the perfectly sharpened cutting edge and a tungsten carbide tool with the rounded cutting edge respectively. Cutting forces are recorded and analyzed as one of main process indicators. The chip morphology and micro milling processes are analyzed in correlation with cutting force variations in the processes. The size effect, minimum chip thickness and their integral effect are quantitatively assessed against the chip formation process. Research results show that the chips formed during the consecutive revolutions are affected jointly by the cutting tool/workpiece material pair and the cutting edge radius in using tungsten carbide tools; whereas the chips formed by using diamond tools are intact and separate. Furthermore, the cutting force and thrust force are of the same order due to the cutting edge radius cannot be ignored. For using a natural diamond tool with the sharp cutting edge, the resultant cutting force is usually two times higher than the thrust force.

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Micro-optical components made from polymethyl methacrylate are increasingly in demand. This article presents an experimental investigation into diamond micro-milling of polymethyl methacrylate components with nanometric surface roughness and its application perspectives. The experimental micro-milling trials with a chemical vapour deposition diamond ball endmill are conducted on a self-developed ultra-precision micro-milling machine (UltraMill) featuring high precision and high dynamic performance. Surface roughness of micro-milled slots using different micro-milling strategies is measured with white light interferometer. Results show that when feed and cutting orientations are perpendicular, smaller surface roughness can be obtained. Micro-milling is carried out on 2 × 2 mm2 areas by applying different micro-milling strategies and process parameters. The results demonstrate that the micro-milling strategy which can generate good surface roughness in slot micro-milling cannot produce expected surface roughness on such a large area (2 × 2 mm2), and machining dynamics plays an important role. By applying two-way joint micro-milling strategy and adjusting process parameters, an optical surface is obtained with roughness of 8.717 nm.

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In this paper, an innovative cutting force modelling concept is presented by modelling cutting forces against micro-cutting processes such as micro-milling, ultraprecision turning and abrasive micromachining, and also taking account of microcutting dynamics. The modelling represents the underlying micro-cutting mechanics and physics in micro-milling in an innovative multi-scale manner, i.e. the specific cutting force at the unit length, unit area and unit volume by considering the size effect, cutting fracture energy, the material modulus, and the cutting heat and temperature partition. A novel instantaneous chip thickness algorithm is introduced to analyse the real chip thickness by taking account of the effects of the micro-tool geometry change brought up by the tool run-out and further contribute to the force model through a numerical iterative algorithm. The measured cutting forces are compensated by a Kalman filter to achieve the accurate cutting forces. This is further utilized to calibrate the model coefficients using least square method. The cutting force modelling is evaluated and validated through well-designed micro-milling trials, which can be used for optimizing the cutting process and tool cutting performance in particular.

Drag reduction in wall-bounded flows can be achieved by the passive flow control technique through the application of bio-inspired ribleted surfaces. In this paper, innovative design and manufacturing of serrate-semi-circular ribleted surfaces are presented with application to friction and drag reduction on engineering surfaces. Firstly, the design of the ribleted surfaces is described particularly focusing on the serrate-semi-circular shaped structures. Secondly, machining of ribleted surfaces by fly-cutting is investigated, covering the utilization of bespoke CVD diamond tools on a micro-milling machine and the corresponding micro fly-cutting processes. Metrology measurement results show good agreement achieved between the designed and machined surface features. Experiment conducted in wind tunnel shows the machined surface can produce 7% in drag reduction. Compared with conventional micro milling, the micro fly-cutting technique resulted from this research illustrates the unique advantage and industrial significance, particularly for manufacturing microstructured surfaces in an industrial scale.

Background: Breast cancer (BC) is a common tumor that seriously affects women's physical/mental health and even life. BC invasion and metastasis are still the main causes of mortality in BC patients. Exosomal long non-coding RNAs (exo-lncRNA) play an important role in cell communication and can help to understand better the physiological and pathological conditions that result from BC. This study investigates new potential targets and functions of the expression profiles of exo-lncRNAs in BC patients through highthroughput screening and bioinformatics.Methods: Samples were collected from two BC patients and one healthy subject. The serum exosomal RNAs were subsequently purified, and a library was established for quality inspection and sequencing. The resultant data was compared with the reference data to obtain the differential expression of exo-lncRNAs, and predict the target genes. To obtain the final results, Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to annotate the function and pathway of the differentially expressed genes.Results: After a comprehensive comparison of the BC patients and healthy subjects, we discovered five up-regulated exo-lncRNAs and six down-regulated exo-lncRNAs of interest. Combining our results with a literature review and screening, we found that VIM-AS1, SNHG8, and ELDR play a role in the progression of BC, with VIM-AS1 predicting 35 target miRNAs; SNHG8 predicting 12 target miRNAs, and ELDR predicting 24 target miRNAs. Target prediction considered that the target gene of VIM-AS1 was VIM and that the target gene of SNHG8 was PRSS12. GO enrichment analysis showed that VIM mainly played a role in cell processes, biological regulation, metabolic regulation, and molecular adhesion, while PRSS12 was enriched through cell metabolism, catalytic activity, and hydrolase activity. KEGG pathway enrichment results also indicated how the VIM protein functions in cancer development through the viral infection signaling pathway and miRNA signaling pathway.Conclusions: There is a significant difference in the expression profiles of serum exo-lncRNAs between BC patients and healthy individuals. This may be closely related to BC's occurrence, development, and metastasis, and therefore provides a theoretical basis for more in-depth studies into exo-lncRNA.

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