Sugar metabolism and accumulation in the fruit of transgenic apple trees with decreased sorbitol synthesis.

Both sorbitol and sucrose are synthesized in source leaves and transported to fruit for supporting fruit growth in tree fruit species of the Rosaceae family. In apple (Malus domestica), antisense suppression of aldose-6-phosphate reductase, the key enzyme for sorbitol synthesis, significantly decreased the sorbitol concentration but increased the sucrose concentration in leaves, leading to a lower sorbitol but a higher sucrose supply to fruit in these plants. In response to this altered carbon supply, the transgenic fruit had lower concentration of sorbitol and much higher concentration of glucose but similar levels of fructose, sucrose, and starch throughout fruit development relative to the untransformed control. Activities of sorbitol dehydrogenase, fructokinase, and sucrose phosphate synthase were lower, whereas activities of neutral invertase, sucrose synthase, and hexokinase were higher in the transgenic fruit during fruit development. Transcript levels of MdSOT1, MdSDHs, MdFK2, and MdSPS3/6 were downregulated, whereas transcript levels of MdSUC1/4, MdSUSY1-3, MdNIV1/3, MdHKs, and MdTMT1 were upregulated in the transgenic fruit. These findings suggest that the Sucrose cycle and the sugar transport system are very effective in maintaining the level of fructose and provide insights into the roles of sorbitol and sucrose in regulating sugar metabolism and accumulation in sorbitol-synthesizing species

Evaluation of medical services from the perspective of COVID-19 vaccine demand satisfaction in Hangzhou, China

The outbreak of COVID-19 has had a huge global impact, and it continues to test the resilience of medical services to emergencies worldwide. In the current post-epidemic era, vaccination has become a highly effective strategy to prevent the spread of COVID-19. However, using conventional mathematical models to evaluate the spatial distribution of medical resources, including vaccination, ignore people\u27s behaviors and choices and make simplifications to the real world. In this study, we use an enhanced model based on the Theory of People Behavior (TPB) to perform a macro analysis of the satisfaction ability of medical resources for vaccination in Hangzhou, China, and attribute the city to a three-level structure. According to the allocation, the supply capacity of vaccination sites is calculated and divided into four categories (good, normal, not bad, and bad). Meanwhile, we raise an assumption based on the result and the general development law of the city and analyze the reasons for the impact of personal behavior on the spatial distribution of medical resources, as well as the relationship between the demand distribution and spatial distribution of medical resources and future development strategies. It is considered that the overall medical resources, especially vaccination in Hangzhou, feature the situation of central supply overflow, and are found to hardly meet the needs of population points in surrounding areas, requiring a more flexible strategy to allocate facilities in these areas

A Mathematical Formulation of DNA Computation

DNA computation is to use DNA molecules for information storing and processing. The task is accomplished by encoding and interpreting DNA molecules in suspended solutions before and after the complementary binding reactions. DNA computation is attractive, due to its fast parallel information processing, remarkable energy efficiency, and high storing capacity. Challenges currently faced by DNA computation are (1) lack of theoretical computational models for applications, and (2) high error rate for implementation. This paper attempts to address these problems from mathematical modeling and genetic coding aspects. The first part of this paper presents a mathematical formulation of DNA computation. The model may serve as a theoretical framework for DNA computation. In the second part, a genetic code based DNA computation approach is presented to reduce error rate for implementation, which has been a major concern for DNA computation. The method provides a promising alternative to reduce error rate for DNA computation

Genetic Code Based Coding and Mathematical Formulation for DNA Computation

DNA computation is to use DNA molecules for information storing and processing. Challenges currently faced by DNA computation are (1) lack of theoretical computational models for applications, and (2) high error rate for implementation. This paper attempts to address these problems from genetic coding and mathematical modeling aspects. The proposed genetic coding approach provides a promising alternative to reduce high error rate. The mathematical formulation lays down groundwork for studying theoretical aspects of DNA computation

A natural mutation-led truncation in one of the two aluminum-activated malate transporter-like genes at the Ma locus is associated with low fruit acidity in apple

Acidity levels greatly affect the taste and flavor of fruit, and consequently its market value. In mature apple fruit, malic acid is the predominant organic acid. Several studies have confirmed that the major quantitative trait locus Ma largely controls the variation of fruit acidity levels. The Ma locus has recently been defined in a region of 150kb that contains 44 predicted genes on chromosome 16 in the Golden Delicious genome. In this study, we identified two aluminum-activated malate transporter-like genes, designated Ma1 and Ma2, as strong candidates of Ma by narrowing down the Ma locus to 65-82kb containing 12-19 predicted genes depending on the haplotypes. The Ma haplotypes were determined by sequencing two bacterial artificial chromosome clones from G.41 (an apple rootstock of genotype Mama) that cover the two distinct haplotypes at the Ma locus. Gene expression profiling in 18 apple germplasm accessions suggested that Ma1 is the major determinant at the Ma locus controlling fruit acidity as Ma1 is expressed at a much higher level than Ma2 and the Ma1 expression is significantly correlated with fruit titratable acidity (R 2=0.4543, P=0.0021). In the coding sequences of low acidity alleles of Ma1 and Ma2, sequence variations at the amino acid level between Golden Delicious and G.41 were not detected. But the alleles for high acidity vary considerably between the two genotypes. The low acidity allele of Ma1, Ma1-1455A, is mainly characterized by a mutation at base 1455 in the open reading frame. The mutation leads to a premature stop codon that truncates the carboxyl terminus of Ma1-1455A by 84 amino acids compared with Ma1-1455G. A survey of 29 apple germplasm accessions using marker CAPS1455 that targets the SNP1455 in Ma1 showed that the CAPS1455A allele was associated completely with high pH and highly with low titratable acidity, suggesting that the natural mutation-led truncation is most likely responsible for the abolished function of Ma for low pH or high acidity in appl

Incident laser modulation by tool marks on micro-milled KDP crystal surface: Numerical simulation and experimental verification

© 2019 Elsevier Ltd Micro-milling has been accepted as the most promising method to repair the micro-defects on the surface of KH2PO4 (KDP) optics. However, surface tool marks are inevitably introduced during the micro-milling repairing process, and could possess great potential risks in lowering the laser-induced damage threshold of KDP optics. The primary cause of laser damage growth of nonlinear crystals has been considered as its internal light intensification. In this work, how the tool marks impact the incident laser modulation as well as the laser-induced damage resistance of micro-milled KDP optics was theoretically and experimentally investigated. The results indicate that periodic tool marks can cause diffraction effect and result in significant relative light intensity modulation (IRmax), up to 5.6 times higher than that inside smooth crystal surfaces. Although the change trends of IRmax with respect to tool marks on both surfaces of KDP optics are similar, the IRmax induced by the rear-surface tool marks is nearly twice higher than that induced by the front-surface tool marks, which means the rear surface with tool marks are more vulnerable to be damaged. The period of tool marks determines the modulation degree and distribution patterns of light intensity inside KDP crystal while the residual height of tool marks can only slightly regulate the modulation degree of light intensity. The tool marks with a period of 1 μm normally give rise to serious light intensification and should be strictly excluded, while the period of tool marks from 10 μm to 20 μm is conducive to the laser damage resistance of micro-milled KDP optics, which were verified by the tests of transmittance capacity and laser damage resistance, and is supposed to be preferred in the actual repairing process of full-aperture KDP optics

Ultra-precision manufacturing technology for difficult-to-machine materials

Ultra-precision manufacturing requires superior components with an impeccable surface finish and accuracy. However, the need for ultra-precision equipment accuracy and problems in machining difficult-to-cut materials pose challenges. Specialized machine tools and understanding the process are vital to overcoming these challenges and improving the surface integrity and application performance

Application of light diffraction theory to qualify the downstream light field modulation property of mitigated KDP crystals

Micro-milling can effectively remove laser damage sites on a KDP (potassium dihydrogen phosphate) surface and then improve the laser damage resistance of the components. However, the repaired KDP surface could cause light propagating turbulence and downstream light intensification with the potential risk to damage downstream optics. In order to analyze the downstream light field modulation caused by Gaussian mitigation pits on KDP crystals, a computational model of the downstream light diffraction based on the angular spectrum theory and the Gaussian repair contour is established. The results show that the phase offset caused by the repaired surface produces a large light field modulation near the rear KDP surface. The modulation generated in the whole downstream light field is greater than that caused by the amplitude change. Therefore, the phase characteristics of the outgoing light could be suggested as a vital research topic for future research on the downstream light field modulation caused by mitigation contours. Significantly, the experimental results on the downstream light intensity distribution have good agreement with the simulation ones, which proves the validity of the established downstream light diffraction model. The phase characterization of the outgoing light is proposed as an evaluation tool in the repair of KDP crystals. The developed analytical method and numerical discrete algorithm could be also applicable in qualifying the repair quality of other optical components applied in high-power laser systems

Effect of milling modes on surface integrity of KDP crystal processed by micro ball-end milling

Micro-milling has been widely considered as the most promising method to repair the micro-defects on the surface of KH2PO4 (KDP) crystal. However, achieving an ultra-smooth repaired surface by ball-end milling remains a longstanding challenge for KDP crystal due to its soft-brittle properties. In micro ball-end milling of KDP crystal, selection of milling mode is the prerequisite to determine the integrated combination of other cutting parameters (e.g. spindle speed, feed rate and the depth of cut). In this paper, with the aim to investigate the influences of the milling mode on the surface integrity of KDP brittle crystal, the micro-groove experiments were carried out comprehensively. All the milling modes were considered (pull-milling, push-milling, up-milling and down-milling) and corresponding cutting parameters selections were also examined. The results demonstrated that the pull-milling and down-milling are both conducive to ductile mode machining, while the push-milling and up-milling cause adverse impacts on the machined surface integrity. In addition, the optimal combination of cutting parameters were also recommended to guide the mitigation of micro-defects on the surface of KDP crystal by micro ball-end milling process