Gas shrinking laminar flow for robust high-power waterjet laser processing technology.

At present, waterjet-assisted laser processing technologies are disadvantaged by low coupling power and poor process reliability, which significantly affect processing efficiency and depth. To address these shortcomings, we propose herein a novel water-gas shrinkage-guided high-power laser processing (WSLP) technology. Firstly, the characteristics of the laminar flow and the light guiding of the water-gas coupled device are optimized. The laminar simulation results show that the water-gas contraction ratio and laminar flow length can be adjusted by changing the water/gas pressure and structural parameters. Secondly, light guiding simulation reveals with a 532 nm 1000W laser, the light guiding efficiency of the shrinkage interface can reach more than 95% within the range of the axial offset 22.1 mm, radial offset 0.62 mm and angular offset 15.8° of the laser focus. Compared with the traditional waterjet-assisted laser processing method, the anti-disturbance capability of the WSLP method is increased by 3.8 times in the axial direction, 2.3 times in the radial direction, and 1.5 times in the angle offset. Thirdly, the feasibility of the laser conduction and processing with this water-gas shrinkage method is verified by experiments. The formation conditions and the relationship of the water-gas laminar flow are investigated. The result shows that the laser coupling efficiency can reach 93% in the low power condition. The research can provide technical support for large depth laser precision machining, in the future.

Research on degradation of penicillins in milk by ß-lactamase using ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry.

The degradation of penicillin G, penicillin V, and ampicillin in milk in the presence of ß-lactamase was investigated by ultra-performance liquid chromatography coupled with electrospray ionization-time-of-flight mass spectrometry. Degradation products of the 3 penicillins in milk were identified based on the fact that the metabolites or degradation products contain a substructure of penicillin, and their degradation pathways in acidic milk in presence of ß-lactamase were developed. The influence of factors on the degradation was investigated, including ß-lactamase dosage, temperature, time, and acidity. The ratio of the 2 degradation products (penicilloic acid and penilloic acid) is different at different temperatures and pH. Penicilloic acid was the dominant species obtained at pH 6 under 40°C, but, being unstable, it could not be used as a standard for accurate analysis of penicilloic acid, and also could not be used as target for detection of penicillins in milk. Penilloic acid was the dominant species obtained at pH 2 above 40°C; it was stable and could be used as a standard for quantitative analysis and as target for detecting whether penicillins were used in milk.

Experimental Investigation of Water Jet-Guided Laser Micro-Hole Drilling of Cf/SiC Composites.

In this paper, water jet-guided laser (WJGL) drilling of Cf/SiC composites was employed and the effects of the processing parameters on the depth and quality of the micro-holes were systematically investigated. Firstly, the depth measurement showed that the increase in processing time and power density led to a significant improvement in micro-hole drilling depth. However, the enhancement of the water jet speed resulted in a pronounced decrease in the depth due to the phenomenon of water splashing. In contrast, the scanning speed, path overlap ratio, pulse frequency, and helium pressure exhibited less effect on the micro-hole depth. Secondly, the microstructural analysis revealed that the increase in power density resulted in the deformation and fracture of the carbon fibers, while the augmentation in water jet speed reduced the thermal defects. Finally, based on the optimization of the processing parameters, a micro-hole of exceptional quality was achieved, with a depth-to-diameter ratio of 8.03 and a sidewall taper of 0.72°. This study can provide valuable guidance for WJGL micro-hole drilling of Cf/SiC composites.

Effect of Synchronized Laser Shock Peening on Decreasing Defects and Improving Microstructures of Ti-6Al-4V Laser Joint.

Repairing processing is a significant method for damaged high-cost Ti-6Al-4V components to decrease economic loss, which usually utilizes a welding technique. For a large-size structural component, welding processing is commonly completed in air conditioning, which makes it difficult to avoid welding defects. To this end, an appropriate matching technique is important for improving welding performance. In the present research, asynchronized laser shock peening (ALSP) and synchronized laser shock peening (SLSP) techniques were utilized to decrease the influence of macro welding defects on laser-welded Ti-6Al-4V joints. The results show that SLSP has a greater effect on inducing surface plastic deformation on Ti-6Al-4V joints with a pitting depth of more than 25 microns while ALSP can lead to a pitting depth of about 15 microns. Through micro-CT observation a long hot crack exists in the central area of as-welded joints with a length of about 2.24 mm, accompanied by lots of pores in different sizes on double sides. After ALSP processing, some pores are eliminated while others are enlarged, and one-side crack tips present closure morphology. However, some microcracks exist on the side-wall of hot cracks. With the influence of SLSP, significant shrinkage of pores can be observed and both sides of crack tips tend to be closed, which presents a better effect than ALSP processing. Moreover, greater effects of grain refinement and thermal stress release could be achieved by SLSP processing than ALSP, which can be ascribed to dynamic recrystallization. For the as-welded joint, the ultimate tensile strength (UTS) and elongation (EL) values are 418 MPa and 0.73%, respectively. The values of UTS and EL in the ALSP processed joint are increased to 437 MPa and 1.07%, which are 4.55% and 46.48% higher than the as-welded joint, respectively. Such values after SLSP processing are 498 MPa and 1.23%, which are 19.14% and 68.49% higher than the as-welded joint, respectively.

Validated method for determination of eight banned nitroimidazole residues in natural casings by LC/MS/MS with solid-phase extraction.

A sensitive method based on solid-phase extraction-liquid chromatography-tandem mass spectrometry interfaced with electrospray ionization (SPE-LC-MS/MS-ESI) was developed for the simultaneous determination of 8 banned nitroimidazole (NOZ) drugs including metronidazole (MNZ), ronidazole (RNZ), dimetridazole (DMZ), tinidazole, ornidazole, secnidazole, metronidazole-OH (MNZOH, the metabolite of MNZ), and 2-hydroxymethyl-1-methyl-5-nitroimidazole (HMMNI, the metabolite of RNZ and DMZ) in natural casings. After extraction with ethyl acetate and evaporation, the NOZs were reconstituted in ethyl acetate and purified on a strong cation-exchange SPE column, and then LC/MS/MS analysis was performed by positive ESI applying multiple reaction monitoring of 2 transition reactions for each compound. The method was validated according to the European Union requirements (Commission Decision 2002/657/EC). Specificity, linearity, decision limit (CCalpha), detection capability (CCbeta), accuracy, and precision were determined. Average recoveries of the 8 NOZs from natural animal casing fortified at 3 levels (0.1, 0.5, and 1 microg/kg) ranged from 87.3 to 116.5%. The calculated CCalpha for NOZs ranged from 0.029 to 0.049 microg/kg, and CCbeta ranged from 0.049 to 0.083 microg/kg. Repeatability was in the range of 3.35-10.1%, and within-laboratory reproducibility was <10.3%.

Long non-coding RNA ZEB2-AS1 expression is associated with disease progression and predicts outcome in gastric cancer patients.

PURPOSE: To explore the correlation of expression of long non-coding RNA (lncRNA) zinc finger E-box binding homeobox 2 antisense RNA 1 (ZEB2-AS1) in gastric cancer tissues, analyze the correlations of its expression level with the clinicopathological features of gastric cancer and the malignant phenotype of tumor cells, and investigate the molecular mechanism of action of ZEB2-AS1 in gastric cancer. METHODS: The expression level of ZEB2-AS1 in gastric cancer tissues and cancer-adjacent tissues in 56 patients was detected by fluorescence real-time quantitative polymerase chain reaction (qRT-PCR). AGS human gastric cancer cells were transiently transfected with small interfering lncRNA (si-lncRNA) ZEB2-AS1 using RNA interference technique, and its effect on proliferation of gastric cancer cells was assessed via MTT assay. Hoechst 33342 staining and flow cytometry were performed to examine the effect of ZEB2-AS1 on the apoptosis of AGS cells and scratch and Transwell assay were applied to detect the effect of si-ZEB2-AS1 on the invasion and metastasis of AGS cells. RESULTS: qRT-PCR results showed that the expression of ZEB2-AS1 in cancer tissues was increased compared with cancer-adjacent tissues. Cell Counting Kit-8 (CCK-8) results indicated that knockdown of ZEB2-AS1 could significantly inhibit the proliferation of AGS cells. Hoechst 33342 staining and flow cytometry demonstrated that knockdown of ZEB2-AS1 obviously promoted the apoptosis of AGS cells. According to scratch and Transwell assay, knocking down ZEB2-AS1 could remarkably inhibit the invasion and metastasis of AGS cells. Western blotting results revealed that knocking down ZEB2-AS1 could inhibit cell invasion and metastasis by suppressing the epithelial to mesenchymal transition (EMT) as well as the expressions of matrix metallopeptidase-2 (MMP-2) and MMP-9 in AGS cells. CONCLUSIONS: The expression of lncRNA ZEB2-AS1 in gastric cancer tissues is significantly higher than in cancer-adjacent tissues. Patients with highly expressed lncRNA ZEB2-AS1 have a poor prognosis, and knockdown of lncRNA ZEB2-AS1 in AGS cells inhibits cell proliferation, invasion and metastasis, and promotes apoptosis.

Early ultrasound-guided percutaneous catheter drainage in the treatment of severe acute pancreatitis with acute fluid accumulation.

The clinical effect of early percutaneous ultrasound guided percutaneous catheter drainage (PCD) in treating severe acute pancreatitis complicated with acute fluid accumulation in the abdominal cavity was analyzed. A total of 178 patients with severe acute pancreatitis complicated with acute fluid accumulation in peritoneal cavity admitted from January, 2011 to January, 2015 to Chuiyangliu Hospital were retrospectively analyzed. Based on the treatment, patients were divided into the following groups: PCD group and conservative treatment control group. Time-period of systemic inflammatory response (SIRS), time-period of abdominal pain, bowel sounds recovery time, dietary recovery time, hospitalization days, white blood cell count, serum amylase, C-reactive protein, serum calcium and complications in both groups were observed and compared. The measurement data between the two groups were presented as mean ± standard deviation (±SD), and analyzed by t-test. Classification data were analyzed by the Chi-square test, with P<0.05 indicating a statistically significant difference. Time-period of systemic inflammatory response (SIRS), time-period of abdominal pain, bowel sounds recovery time, dietary recovery time and hospitalization days were shorter in the PCD group than those in the control group (P=0.001). Improvements of white blood cell count, serum amylase, C-reactive protein and serum calcium were better than those of the control group (P<0.001), the rate of transferring to surgical department in the PCD group was lower than that of the control group (P=0.042), and complications of severe acute pancreatitis were not significantly different in the two groups (P>0.05). In this study, 6 adverse events occurred in the PCD group, accounting for 7.9% (6/76), including 1 case of puncture bleeding and 5 cases of obstruction. In conclusion, early ultrasound-guided PCD in treating severe acute pancreatitis is effective and safe.

[Study of chemical constituents of the essential oil from Inula britannica L. by GC-MS].

OBJECTIVE: The chemical components of the essential oil from Inula britannica L., which were collected from Yuncheng area of Shanxi province, were analyzed by GC-MS. METHODS: The essential oil was extracted from Inula britannica L. by steam distillation, the components were separated with the capillary chromatographic columns, the amount of the components from the essential oil was determined by normalization method. The components separated were identified by data search system. The chromatographic conditions were as follows: DB-5 (30m x 0.25mm, 0.25 microm) capillary column; High purity helium was used as carrier gas, and the flow rate was 1.0 ml/min; Column temperature: 70 degrees C keeping 2min, from 70 degrees C to 230 degrees C at rising rate 10 degrees C/min and keeping 10 min; Split ratio 15:1; Injector temperature 250 degrees C. RESULTS: 62 peaks were identified representing 68.4% of the total contents. Main component was 1-Benzoxepin-3-ol,2,3,4,5-tetrahydro-(4. 276% ). CONCLUSION: The method is so reliable, stable, and good reproducible that can be applied to the analysis of the essential oil from Inula britannica L.

A novel method for preparation of tissue microarray.

AIM: To improve the technique of tissue microarray (tissue chip). METHODS: A new tissue microarraying method was invented with a common microscope installed with a special holing needle, a sampling needle, and a special box fixing paraffin blocks on the microscope slide carrier. With the movement of microscope tube and objective stage on vertical and cross dimensions respectively, the holing procedure on the recipient paraffin blocks and sampling procedure of core tissue biopsies taken from the donor blocks were performed with the refitted microscope on the same platform. The precise observation and localization of representative regions in the donor blocks were also performed with the microscope equipped with a stereoscope. RESULTS: Highly-qualified tissue chips of colorectal tumors were produced by a new method, which simplified the conventional microarraying procedure, and was more convenient and accurate than that employing the existing tissue microarraying instruments. CONCLUSION: Using the refitted common microscope to produce tissue microarray is a simple, reliable, cost-effective and well-applicable technique.

[Determination of six progesterones in milk by on-line cleanup liquid chromatography-tandem mass spectrometry].

A new method using TurboFlow on-line cleanup liquid chromatography combined with tandem mass spectrometry (MS/MS) has been developed for simultaneous determination of six progesterones including 19-norethindrone, 17alpha-hydroxyprogesterone, medroxyprogesterone, megestrol acetate, progesterone and melengestrol acetate in milk. Samples were extracted by acetonitrile. The analytes in extract were on-line purified directly on Cyclone-P purification column where the sample matrices were washed away. Subsequently, the analytes which were eluted from the extraction column onto Phenyl-Hexyl column were separated with a gradient elution, and detected with electrospray ionization mass spectrometry in the positive scan mode using multiple reaction monitoring (MRM). The isotope internal standards were employed for quantification. As a result, the linearities were satisfactory with the correlation coefficients of > 0.999 at concentrations ranging from 0.1 microg/L to 50 microg/L. Based on the repeated analysis of a known blank sample, the limit of quantification (LOQ) is 0.5 microg/kg. Average recoveries of the analytes fortified at three levels (1, 5 and 25 microg/kg) ranged from 90.8% to 107.5%, and the relative standard deviations (RSDs) ranged from 6.3% to 11.8%. This proposed method is simple, rapid, sensitive and highly selective, and can be applied to simultaneous identification an quantification of the six progesterones in milk.

[Simultaneous determination of penicillin and their major enzymatic metabolites in milk and milk powder by high performance liquid chromatography-tandem mass spectrometry].

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/ MS) method has been developed for the determination of eight compounds in milk and milk powder. They are four penicillins (penicillin G, penicillin V, amoxicillin and ampicillin) and four major beta-lactamase enzymatic metabolites of them (penilloic acid G, penilloic acid V, amoxiilloic acid and ampilloic acid). The compounds were extracted from the samples with acetonitrile and water, cleaned-up by HLB solid-phase extraction cartridges, and then detected by HPLC-MS/MS and quantified by external standard method. The linearities were satisfactory with the correlation coefficients > 0.99 at the mass concentrations ranging from 4 microg/L to 200 microg/L for penicillins and from 10 microg/L to 500 microg/L for enzymatic metabolites. The limits of detection and the limits of quantification were 5-50 microg/kg (S/N > or = 3) and 8-100 microg/kg (S/N > or = 10), respectively. The average recoveries of the eight compounds were 83.48%-96.97% in milk and 82.70%-95.14% in milk powder. The relative standard deviations (RSDs) in milk and milk powder were 3.86%-10.87% and 3.02%-9.81%, respectively. In conclusion, the established method is convenient, accurate and sensitive so that it can be applied to the determination of penicillin residues and enzymatic metabolites in milk and milk powder.

Determination of diclazuril, toltrazuril and its two metabolites in poultry tissues and eggs by gel permeation chromatography-liquid chromatography-tandem mass spectrometry.

A new procedure has been described for the extraction of diclazuril (DIZ), toltrazuril (TOZ) and its two main metabolites toltrazuril sulphoxide (TZSO) and toltrazuril sulphone (TZS) from poultry tissues and eggs, using gel permeation chromatography (GPC). The analytes and the deuterated internal standard were extracted from the samples with ethyl acetate. The analytes were measured by LC coupled to an electrospray ionization tandem mass spectrometer operating in the negative ion mode. Excellent linear dynamic range was observed from 1 to 500 µg/L with the correlation coefficients (R(2)) better than 0.99 for all analytes. The method LOQ of the four analytes in real samples was 1.2 µg/kg for DIZ and TOZ, and 1.8 µg/kg for TZSO and TZS. These values are far lower than the maximum residue limits (MRLs) established by several control authorities. The developed method was accurate with overall recoveries in four matrices.

[Determination of 46 plasticizers in food contact polyvinyl chloride packaging materials and their migration into food simulants by gas chromatography-mass spectrometry].

A gas chromatography-mass spectrometry (GC-MS) method was developed for the determination of 46 plasticizers in food contact polyvinyl chloride (PVC) packaging materials and their migration into food simulants, i. e. water, 3% acetic acid, 10% ethanol and olive oil. Plasticizers in the PVC packaging materials, aqueous food simulants and olive oil food simulants were extracted by the dissolution-precipitation, liquid-liquid extraction and gel permeation chromatography (GPC) approaches, respectively. The extracts were analyzed by GC-MS in selective ion monitoring (SIM) mode and quantified using the external standard method. The cal-ibration curves were linear in the ranges of 0.1-2.0 mg/L with the correlation coefficients of 0.9910-0. 999 9. The limits of detection were from 0. 005 mg/kg to 0. 05 mg/kg ( S/N = 5 ). The recoveries at 3 spiked levels were 69.51%-107. 21% and the relative standard deviations (RSDs n = 6) ranged from 3.53% to 18.95%. These results show that this method is fast, sensitive and accurate for the qualitative and quantitative determination of plasticizers in food contact plastic products and 4 types of food simulants.

[A novel method for fabrication of tissue microarray].

BACKGROUND & OBJECTIVE: Tissue chip (tissue microarray, TMA) is one of the most important biochip techniques, just following the gene chip and the protein chip, which is one of the most important functional genomics and proteomics research methods in the post-genomic era. However, the present TMA technology has certain shortcomings, such as lack of advanced instruments, tedious procedure, and low sampling accuracy, etc. This new method was designed to improve the technology of TMA. METHODS: A common microscope was installed with a special holing needle, a sampling needle, and a proper box to fix paraffin blocks on the microscope carrier. With the precise mechanical control of microscope, the holing procedure on the recipient paraffin blocks and sampling procedure of core tissue biopsies were performed with the re-equipped microscope. The precise observation and localization of sampling regions were also performed using the same microscope equipped with a stereoscope. RESULTS: The new method simplified TMA procedure, and the whole process of holing, locating, and sampling was performed with the same instrument on the same platform. The single-use holing and sampling needles were first applied to maintain higher accuracy and to avoid the tissue remains and contamination among different samples. And high-qualified tissue chips of colorectal tumors were produced successfully by the new method. CONCLUSION: Using the re-equipped common microscope to fabricate tissue microarrays is a simple, reliable, cost-effective,and well-applicable technique.