A note on the tensor and vector exchange contributions to KKˉ→KKˉ,DDˉ→DDˉK \bar K \to K \bar K, D \bar D \to D \bar D and π+π−→π+π−\pi^+ \pi^-\to \pi^+ \pi^- reactions

In this note we study the tensor and vector exchange contributions to the elastic reactions involving the pseudoscalars mesons $\pi^+ \pi^-$, $K^{+}K^{-}$ and $D^{+}D^{-}$. In the case of the tensor-exchange contributions we assume that an intermediate tensor $f_2(1270)$ is dynamically generated from the interaction of two virtual $\rho$ mesons, with the use of a pole approximation. The calculation of the two-loop amplitude is facilitated since the triangle loops can be factorized and computed separately. The results show very small contributions coming from the tensor-exchange mechanisms when compared with those from the vector-exchange processes.Comment: 8 pages, 5 figure

B+B^+ decay to K+ηηK^+\eta\eta with (ηη\eta\eta) from the DDˉ(3720)D\bar{D}(3720) bound state

We search for a $B$ decay mode where one can find a peak for a $D \bar{D}$ bound state predicted in effective theories and in Lattice QCD calculations, which has also been claimed from some reactions that show an accumulated strength in $D \bar{D}$ production at threshold. We find a good candidate in the $B^+\to K^+ \eta\eta$ reaction, by looking at the $\eta\eta$ mass distribution. The reaction proceeds via a first step in which one has the $B^+\to D_s^{*+} \bar{D}^0$ reaction followed by $D_s^{*+}$ decay to $D^0 K^+$ and a posterior fusion of $D^0 \bar{D}^0$ to $\eta \eta$, implemented trough a triangle diagram that allows the $D^0 \bar{D}^0$ to be virtual and produce the bound state. The choice of $\eta\eta$ to see the peak is based on results of calculations that find the $\eta\eta$ among the light pseudoscalar channels with stronger coupling to the $D \bar{D}$ bound state. We find a neat peak around the predicted mass of that state in the $\eta\eta$ mass distribution, with an integrated branching ratio for $B^+\to K^+$ ($D\bar{D}$, bound) ; ($D\bar{D}$, bound) $\to \eta \eta$ of the order of $1.5 \times 10^{-4}$, a large number for hadronic $B$ decays, which should motivate its experimental search

New pre-processing technologies for fruits and vegetables

Horticultural products constitute one of the most perishable foods and its availability throughout the year requires the application of preservation methods. Traditionally, horticultural products are preserved by freezing, allowing these products to reach longer shelf-life periods. Until nowadays, freezing has been preceded by a blanching step, which has been considered as an efficient and safe food preservation method. However, besides its reliable efficiency in terms of food safety, blanching normally induces various chemical reactions, leading to quality deterioration by producing undesirable changes in sensory and nutritional qualities, affecting the balance between high quality and safety. The increasing consumer quality demanding standards has spurred the search for new and gently processing technologies that prolong shelf-life without the detrimental effects caused by severe heating. Non-thermal methods have emerged as attractive alternatives to conventional methods of thermal processing. There are several new nonthermal technologies of potential interest to the industry, such as ozone, UV-C irradiation, ultrasound, high pressure, and electrical pulses. The application of nonthermal technologies to food processing and preservation may yield processed foods with minor losses of colour, flavour, texture and nutrients, while retaining the desired shelf-life and safety. Ozone, UV-C irradiation, and ultrasound treatments are promising techniques for the fruits and vegetables industry. However, their efficiency depends on the product/microorganism under consideration

Study on thermosonication and ultraviolet radiation processes as an alternative to blanching for some fruits and vegetables

The impacts of ultraviolet-C radiation, blanching by heat, and combination of heat/ultrasounds (thermosonication) were studied for Listeria innocua (inoculated) in red bell peppers, total mesophiles in strawberries and total coliforms in watercress, in the temperature range 50–65 °C. Quality attributes such as colour and firmness were studied for all products, and total anthocyanins content was additionally determined for strawberries. Results showed that ultraviolet- C radiation was the least effective treatment in terms of microbial load reduction and was equivalent to a simple water washing. Log reductions were 1.05±0.52 for L. innocua, 0.53±0.25 for total coliforms and 0.26±0.18 for total mesophiles. This treatment had the lowest impact on the quality parameters analysed. Thermosonication treatment was similar to heat blanching for all microorganism/product tested, excepted for total coliforms in watercress at 65 °C, in which thermosonication had a higher effect (p<0.05). Heat blanching at 65 °C allowed 7.43±0.12 log-cycles reduction, while loads were diminished by 8.24±0.13 log-cycles if thermosonication at the same temperature was applied. Thermosonication also allowed better quality retention, when compared to heat blanching at the same temperatures. The impact of thermosonication on microbial load reductions was statistically significant and thermosonicated samples retained quality attributes better than heat blanched ones at the same temperatures (p<0.05). Hence, it can be concluded that thermosonication is a promising process and may be a favourable alternative to the conventional thermal treatments

Influence of aqueous ozone, blanching and combined treatments on microbial load of red bell peppers, strawberries and watercress

The effectiveness of ozone in aqueous solution treatment on microbial inactivation was studied for three combinations microorganism/food: Listeria innocua/red bell peppers (artificially inoculated), total mesophiles/strawberries, and total coliforms/watercress, with two concentrations (0.3 and 2.0 ppm). Blanching treatments (50-60 degrees C) were also individually applied and in combination with ozone, for studying possible synergistic effects. In relation to ozone treatments, the highest microbial reductions were obtained for the highest concentration with the highest treatment time (3 min). Under those conditions. L. innocua/peppers, total mesophiles/strawberries and total coliforms/watercress were reduced respectively 2.8 +/- 0.5, 2.3 +/- 0.4 and 1.7 +/- 0.4 log-cycles. However, a substantial portion of the microbial populations were reduced by water washing alone, and the presence of ozone generally added an additional reduction of 0.5-1.0 log-cycles. If ozone at the highest concentration is used, the treatment impacts on L. innocua/peppers and total mesophiles/strawberries load reductions were equivalent to a blanching at 50 degrees C (for the same treatment times). Combining blanching and ozone did not generate synergistic effects, and in some situations microbial reductions were lower than the ones observed when treatments were applied independently.info:eu-repo/semantics/acceptedVersio