295 research outputs found
Analytical Methods Inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometry (ICP-oa-TOF-MS) analysis of heavy metal content in Indocalamus tesselatus samples
a b s t r a c t Indocalamus tesselatus is one of the most popular packing materials in China. Heavy metals in Chinese I. tesselatus samples have received great interest because they are related to health. A simple and fast method for the determination of Pb, Cd, Mn, Ni, Cr, As, Hg, Cu and Zn, by inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometry (ICP-oa-TOF-MS), following microwave closed vessel digestion of samples, was proposed. The method was validated using standard reference material (GBW 07605-Tea). Samples of I. tesselatus from five different regions of China were analysed using the proposed method. Heavy metals contents from different regions were found at different levels. Their low contents of heavy metals showed that collection areas were not polluted and all collected I. tesselatus samples could be unreservedly used as food packing materials without any health risk
Multidifferential study of identified charged hadron distributions in -tagged jets in proton-proton collisions at 13 TeV
Jet fragmentation functions are measured for the first time in proton-proton
collisions for charged pions, kaons, and protons within jets recoiling against
a boson. The charged-hadron distributions are studied longitudinally and
transversely to the jet direction for jets with transverse momentum 20 GeV and in the pseudorapidity range . The
data sample was collected with the LHCb experiment at a center-of-mass energy
of 13 TeV, corresponding to an integrated luminosity of 1.64 fb. Triple
differential distributions as a function of the hadron longitudinal momentum
fraction, hadron transverse momentum, and jet transverse momentum are also
measured for the first time. This helps constrain transverse-momentum-dependent
fragmentation functions. Differences in the shapes and magnitudes of the
measured distributions for the different hadron species provide insights into
the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb
public pages
Study of the decay
The decay is studied
in proton-proton collisions at a center-of-mass energy of TeV
using data corresponding to an integrated luminosity of 5
collected by the LHCb experiment. In the system, the
state observed at the BaBar and Belle experiments is
resolved into two narrower states, and ,
whose masses and widths are measured to be where the first uncertainties are statistical and the second
systematic. The results are consistent with a previous LHCb measurement using a
prompt sample. Evidence of a new
state is found with a local significance of , whose mass and width
are measured to be and , respectively. In addition, evidence of a new decay mode
is found with a significance of
. The relative branching fraction of with respect to the
decay is measured to be , where the first
uncertainty is statistical, the second systematic and the third originates from
the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb
public pages
The Synthesis and Characterization of Hydroxyapatite-ÎČ-Alanine Modified by Grafting Polymerization of Îł-Benzyl-L-glutamate-N-carboxyanhydride
In this study, hydroxyapatite (HAP) was surface-modified by the addition of ÎČ-alanine (ÎČ-Ala), and the ring-opening polymerization of Îł-benzyl-L-glutamate-N-carboxy-anhydride (BLG-NCA) was subsequently initiated. HAP containing surface poly-Îł-benzyl-L-glutamates (PBLG) was successfully prepared in this way. With the increase of PBLG content in HAP-PBLG, the solubility of HAP-PBLG increased gradually and it was ultimately soluble in chloroform. HAP-PLGA with surface carboxyl groups was obtained by the catalytic hydrogenation of HAP-PBLG. In the process of HAP modification, the morphology changes from rod to sheet and from flake to needle. The effect of BLG-NCA concentration on the character of hydroxyapatite-ÎČ-alanine-poly(Îł-benzyl-L-glutamate) (HAP-PBLG) was investigated. The existence of amino acids on the HAP surfaces was confirmed in the resulting Fourier transform infrared (FTIR) spectra. The resulting powder X-ray diffraction patterns indicated that the crystallinity of HAP decreased when the ratio of BLG-NCA/HAP-NH2 increased to 20/1. Transmission electron microscopy (TEM) indicated that the particle size of HAP-PBLG decreased significantly and that the resulting particles appeared less agglomerated relative to that of the HAP-NH2 crystals. Furthermore, 1H-NMR spectra and FTIR spectra revealed that hydroxyapatite-ÎČ-alanine-poly (L-glutamic acid) (HAP-PLGA) was able to successfully bear carboxylic acid groups on its side chains
Characterization of Antimicrobial Poly (Lactic Acid)/Nano-Composite Films with Silver and Zinc Oxide Nanoparticles
Antimicrobial active films based on poly (lactic acid) (PLA) were prepared with nano-silver (nano-Ag) and nano-zinc oxide (nano-ZnO) using a solvent volatilizing method. The films were characterized for mechanical, structural, thermal, physical and antimicrobial properties. Scanning electron microscopy (SEM) images characterized the fracture morphology of the films with different contents of nano-Ag and nano-ZnO. The addition of nanoparticles into the pure PLA film decreased the tensile strength and elasticity modulus and increased the elongation of breaksâin other words, the flexibility and extensibility of these composites improved. According to the results of differential scanning calorimetry (DSC), the glass transition temperature of the PLA nano-composite films decreased, and the crystallinity of these films increased; a similar result was apparent from X-ray diffraction (XRD) analysis. The water vapor permeability (WVP) and opacity of the PLA nano-composite films augmented compared with pure PLA film. Incorporation of nanoparticles to the PLA films significantly improved the antimicrobial activity to inhibit the growth of Escherichia coli. The results indicated that PLA films with nanoparticles could be considered a potential environmental-friendly packaging material
High Pressure Treatment for Improving Water Vapour Barrier Properties of Poly(lactic acid)/Ag Nanocomposite Films
Effects of high pressure treatment (0, 200 and 400 MPa) on water vapour barrier, microstructure, thermal, and mechanical properties of poly (lactic acid) (PLA)/Ag nanocomposite films were investigated. The migration behavior of nano-Ag from the nanocomposite films in the presence of 50% (v/v) ethanol as a food simulant was also studied. The water vapour barrier properties increased as pressure was applied to film-forming solutions. High pressure treatment enhanced the mutual effect between PLA and nanoparticles, leading to a more compact network structure in PLA/Ag nanocomposite films. Furthermore, PLA/Ag nanocomposite films treated by high pressure were significantly affected by microstructure, thermal, and mechanical properties when, compared with untreated samples. High pressure treatment at 200 to 400 MPa significantly (p < 0.05) reduced the migration of nano-Ag from the films. Overall, high pressure treatment on film-forming solutions showed potential in improving the functional properties of nanocomposite films, especially in relation to water vapour barrier properties
Physicochemical Properties and Microbial Quality of Tremella aurantialba Packed in Antimicrobial Composite Films
The effects of poly(lactic acid) (PLA)-based film with inorganic antimicrobial nano-TiO2 and nano-Ag on the physicochemical and microbial quality of Tremella aurantialba stored at 4 ± 1 °C for 16 days was investigated. Rosemary essential oil (REO, 9 wt %) was added into PLA film as plasticizer. Low-density polyethylene (LDPE) and PLA film was used as the controls. The experiment measured physicochemical properties and microbial levels, such as weight loss, firmness, vitamin C, color, microbiological quality, and sensory quality. Although Tremella aurantialba packed by nano-composite films had the highest weight loss (4.96% and 5.17%) at the end of storage, it was still in the vicinity of 5%. Tremella aurantialba packed with nano-composite films were significantly (p < 0.05) firmer than those packed by LDPE, PLA, and PLA/REO films. The nano-composite films were more effective in reducing vitamin C and microbial counts and preserving the color of Tremella aurantialba than the other three groups. The overall acceptability of Tremella aurantialba packed by the nano-composite films still remained good and within the limits of marketability after 12 days of storage. The results suggested that the proposed nano-composite films could maintain the quality of Tremella aurantialba and extend its postharvest life
Poly(lactide-co-trimethylene carbonate) and Polylactide/Polytrimethylene Carbonate Blown Films
In this work, poly(lactide-co-trimethylene carbonate) and polylactide/ polytrimethylene carbonate films are prepared using a film blowing method. The process parameters, including temperature and screw speed, are studied, and the structures and properties of the P(LA-TMC) and PLA/PTMC films are investigated. The scanning electron microscope (SEM) images show that upon improving the content of TMC and PTMC, the lamellar structures of the films are obviously changed. With increasing TMC monomer or PTMC contents, the elongation at the break is improved, and the maximum is up to 525%. The water vapor permeability (WVP) results demonstrate that the WVP of the PLA/PTMC film increased with the increase in the PTMC content, whereas the WVP of the P(LA-TMC) film decreased. Thermogravimetric (TG) measurements reveal that the decomposition temperatures of the P(LA-TMC) and PLA/PTMC films decrease with increases in the TMC and PTMC contents, respectively, but the processing temperature is significantly lower than the initial decomposition temperature. P(LA-TMC) or PLA/PTMC film can extend the shelf life of apples, for instance, like commercial LDPE film used in fruit packaging in supermarkets
Development of Smart Films of a Chitosan Base and <i>Robusta</i> Coffee Peel Extract for Monitoring the Fermentation Process of Pickles
Smart film is widely used in the field of food packaging. The smart film was prepared by adding anthocyanin-rich Robusta coffee peel (RCP) extract into a chitosan (CS)âglycerol (GL) matrix by a solution-casting method. By changing the content of RCP (0, 10%, 15% and 20%) in the CSâGL film, the related performance indicators of CSâGLâRCP films were studied. The results showed that the CSâGLâRCP films had excellent mechanical properties, and CSâGLâRCP15 film maintained the tensile strength (TS) of 16.69 MPa and an elongation-at-break (EAB) of 18.68% with RCP extract. CSâGLâRCP films had the best UV-vis light barrier property at 200â350 nm and the UV transmittance was close to 0. The microstructure observation results showed that CSâGLâRCP films had a dense and uniform cross section, which proved that the RCP extract had good compatibility with the polymer. In addition, the CSâGLâRCP15 film was pH-sensitive and could exhibit different color changes with different pH solutions. So, the CSâGLâRCP15 film was used to detect the fermentation process of pickles at 20 ± 1 °C for 15 days. The pickles were stored in a round pickle container after the boiling water had cooled. The color of the CSâGLâRCP15 film changed significantly, which was consistent with the change of pickles from fresh to mature. The color of the smart film changed significantly with the maturity of pickles, and the difference of ÎE of film increased to 8.89 (15 Days), which can be seen by the naked eye. Therefore, CSâGLâRCP films prepared in this study provided a new strategy for the development of smart packaging materials
Effects of PLA Film Incorporated with ZnO Nanoparticle on the Quality Attributes of Fresh-Cut Apple
A novel nanopackaging film was synthesized by incorporating ZnO nanoparticles into a poly-lactic acid (PLA) matrix, and its effect on the quality of fresh-cut apple during the period of preservation was investigated at 4 ± 1 °C for 14 days. Six wt % cinnamaldehyde was added into the nano-blend film. Scanning electron microscope (SEM) analysis showed a rougher cross-section of the nano-blend films and an X-ray diffraction (XRD) was carried out to determine the structure of the ZnO nanoparticles. Compared to the pure PLA film, the nano-blend film had a higher water vapor permeability (WVP) and lower oxygen permeability. With the increase of the nanoparticles (NPs) in the PLA, the elongation at break (Δ) and elastic modulus (EM) increased, while tensile strength (TS) decreased. Thermogravimetric analysis (TGA) presented a relatively good thermostability. Most importantly, the physical and biochemical properties of the fresh-cut apple were also measured, such as weight loss, firmness, polyphenol oxidase (PPO), total phenolic content, browning index (BI), sensory quality, and microbiological level. The results indicated that nano-blend packaging films had the highest weight loss at the end of storage compared to the pure PLA film; however, nanopackaging provided a better retention of firmness, total phenolic countent, color, and sensory quality. It also had a remarkable inhibition on the growth of microorganisms. Therefore, Nano-ZnO active packaging could be used to improve the shelf-life of fresh-cut produce
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