Laparoscopy versus open appendectomy for elderly patients, a meta-analysis and systematic review.

BACKGROUND: Appendicitis in elderly patients is associated with increased risk of postoperative complications. The choice between laparoscopy and open appendectomy remains controversial in treating elderly patients with appendicitis. METHODS: Comprehensive search of literature of MEDLINE, Embase, Cochrane Library and ClinicalTrials was done in January 2019. Studies compared laparoscopy and open appendectomy for elderly patients with appendicitis were screened and selected. Postoperative mortality, complications, wound infection, intra-abdominal abscess and operating time, length of hospital stay were extracted and analyzed. The Review Manage 5.3 was used for data analysis. RESULTS: Twelve studies with 126,237 patients in laparoscopy group and 213,201 patients in open group. Postoperative mortality was significantly lower following laparoscopy (OR, 0.33; 95% CI, 0.28 to 0.39). Postoperative complication and wound infection were reduced following laparoscopy ((OR, 0.65 95% CI, 0.62 to 0.67; OR,0.27, 95% CI, 0.22 to 0.32). Intra-abdominal abscess was similar between LA and OA (OR,0.44;95% CI, 0.19 to 1.03). Duration of surgery was longer following laparoscopy and length of hospital stay was shorter following laparoscopy (MD, 7.25, 95% CI, 3.13 to 11.36; MD,-2.72, 95% CI,-3.31 to - 2.13). CONCLUSIONS: Not only laparoscopy is safe and feasible, but also it is related with decreased rates of mortality, post-operative morbidity and shorter hospitalization.

An integrated high-throughput strategy for rapid screening of poly(γ-glutamic acid)-producing bacteria.

Poly(γ-glutamic acid) (γ-PGA) is a promising biomaterial with a wide range of unique applications. To extensively screen γ-PGA-producing bacteria with high yield and different molecular weight, we developed an integrated high-throughput strategy. Firstly, γ-PGA-producing bacteria were selected in a primary screen plate containing a basic dye (neutral red) based on the concentric zone formed through the electrostatic interaction between the dye and the secreted acidic polymer γ-PGA. Then, the isolates were cultured in 50 ml tubes instead of 250 ml flasks. A good correlation of fermentation results in 50 ml tubes and 250 ml flasks was observed. Thirdly, the γ-PGA yield and weight-average molecular weight (M (w)) were simultaneously determined by spectrophotomic assay (UV assay) and neutral red plate assay. The results showed that the diameter of the concentric zone varied among isolates and was negatively correlated with the weight-average molecular weight of γ-PGA. The accuracy of the methods was comparable to that of high-performance liquid chromatography and gel permeation chromatography assay. Lastly, γ-PGA obtained from the target isolates was rapidly identified using thin layer chromatography assay. With this strategy, 13 bacteria with high yield and various molecular weights of γ-PGA from 500 obvious single colonies on the primary screen plate were obtained.

Approach dealing with the temporal profile of a probe laser pulse in the open-aperture Z-scan.

An approach is proposed to analyze the two- and three-photon absorption process using the open-aperture Z-scan technique. The normalized transmittance equations of one pulse energy presented here can be used to investigate the effect of different temporal profiles of excitation laser pulses on the nonlinear absorption coefficients (NACs). The numerical simulations show that our method is well in accordance with the usual Z-scan in determination of two- and three-photon absorption coefficients in 0.6-1.0 ranges of nonlinear energy transmittance for the typical pulse models, such as Gaussian, sech2, Lorentz, and asymmetric sech2 models. Our results suggest that the introduced parameter in relation to the pulse envelope in the approach may become a candidate for the parameters taking account of the NAC deviation from the pulse profiles of the probe laser.

Characterization of titanium nitride coatings deposited by metal plasma ion pre-implantation and cathodic arc evaporation.

Titanium nitride coatings are deposited using a hybrid system of cathodic arc evaporation and metal plasma ion implantation. The implant sources selected are Ti and C. Subsequent ion bombardment along with the conventional cathodic arc evaporation are applied to the deposition of TiN film. Implantation causes the increase of nucleation site density, favoring the formation of denser films. The increased density of nucleation sites due to high-energy ion impingement and the surface modification contribute to the fine microstructure of the TiN films. The critical loads evaluated from scratch tests are 60 N, 70 N and 78 N for unimplant-TiN, C+/TiN and Ti2+/TiN, respectively. It demonstrates the advantage of implant pre-treatment on adhesion strength. Pre-implantation of high dose Ti2+ and C+ (about 2 x 10(17) ions/cm2) also results in an improvement of the mechanical properties. Pin-on-disk wear analyses demonstrate a prolonged wear life of TiN coatings by Preimplantation of Ti2+ and C+ ions. The TiN surface modification by pre-implant ions (Ti2+ or C+) is investigated through the microstructure, adhesion strength and wears resistance.

Mechanical, Anisotropic, and Electronic Properties of XN (X = C, Si, Ge): Theoretical Investigations.

The structural, mechanical, elastic anisotropic, and electronic properties of Pbca-XN (X = C, Si, Ge) are investigated in this work using the Perdew-Burke-Ernzerhof (PBE) functional, Perdew-Burke-Ernzerhof for solids (PBEsol) functional, and Ceperly and Alder, parameterized by Perdew and Zunger (CA-PZ) functional in the framework of density functional theory. The achieved results for the lattice parameters and band gap of Pbca-CN with the PBE functional in this research are in good accordance with other theoretical results. The band structures of Pbca-XN (X = C, Si, Ge) show that Pbca-SiN and Pbca-GeN are both direct band gap semiconductor materials with a band gap of 3.39 eV and 2.22 eV, respectively. Pbca-XN (X = C, Si, Ge) exhibits varying degrees of mechanical anisotropic properties with respect to the Poisson's ratio, bulk modulus, shear modulus, Young's modulus, and universal anisotropic index. The (001) plane and (010) plane of Pbca-CN/SiN/GeN both exhibit greater elastic anisotropy in the bulk modulus and Young's modulus than the (100) plane.

Pnma-BN: Another Boron Nitride Polymorph with Interesting Physical Properties.

Structural, mechanical, electronic properties, and stability of boron nitride (BN) in Pnma structure were studied using first-principles calculations by Cambridge Serial Total Energy Package (CASTEP) plane-wave code, and the calculations were performed with the local density approximation and generalized gradient approximation in the form of Perdew-Burke-Ernzerhof. This BN, called Pnma-BN, contains four boron atoms and four nitrogen atoms buckled through sp³-hybridized bonds in an orthorhombic symmetry unit cell with Space group of Pnma. Pnma-BN is energetically stable, mechanically stable, and dynamically stable at ambient pressure and high pressure. The calculated Pugh ratio and Poisson's ratio revealed that Pnma-BN is brittle, and Pnma-BN is found to turn brittle to ductile (~94 GPa) in this pressure range. It shows a higher mechanical anisotropy in Poisson's ratio, shear modulus, Young's modulus, and the universal elastic anisotropy index AU. Band structure calculations indicate that Pnma-BN is an insulator with indirect band gap of 7.18 eV. The most extraordinary thing is that the band gap increases first and then decreases with the increase of pressure from 0 to 60 GPa, and from 60 to 100 GPa, the band gap increases first and then decreases again.