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In modern power systems, power transformers are considered vital components that can ensure the grid’s continuous operation. In this regard, studying the breakdown in the transformer becomes necessary, especially its insulating system. Hence, in this study, Box–Behnken design (BBD) was used to introduce a prediction model of the breakdown voltage (VBD) for the transformer insulating oil in the presence of different barrier effects for point/plane gap arrangement with alternating current (AC) voltage. Interestingly, the BBD reduces the required number of experiments and their costs to examine the barrier parameter effect on the existing insulating oil VBD. The investigated variables were the barrier location in the gap space (a/d)%, the relative permittivity of the barrier materials (εr), the hole radius in the barrier (hr), the barrier thickness (th), and the barrier inclined angle (θ). Then, only 46 experiment runs are required to build the BBD model for the five barrier variables. The BBD prediction model was verified based on the statistical study and some other experiment runs. Results explained the influence of the inclined angle of the barrier and its thickness on the VBD. The obtained results indicated that the designed BBD model provides less than a 5% residual percentage between the measured and predicted VBD. The findings illustrated the high accuracy and robustness of the proposed insulating oil breakdown voltage predictive model linked with diverse barrier effects.

A field experiment was designed to assess the impacts of various maize straw (stover) returning methods on the basic soil physicochemical properties and soil quality index in Jilin (NE China). The five treatments were no return of straw residues (CK), straw incorporated evenly into the soil using the crashing-ridging technique (EIS), straw mulching (SM), straw plowed into the soil (SP), and straw returned in granulated form (SG). Relative to the no straw return, EIS effectively reduced soil bulk density and penetration resistance, increased soil total organic carbon (TOC), macroaggregate-associated carbon content, and the accumulation of soil humus. Furthermore, EIS improved soil structure and soil aggregate stability and significantly increased the soil quality index. Among the various straw returning treatments, SM and SG significantly promoted soil macroaggregation and increased macroaggregate-associated carbon content by 23.69% and 21.70% at the soil surface, respectively (as compared with the control). Compared to SM, SP, and SG, EIS significantly enhanced the aliphaticity and hydrophobicity of soil organic carbon. These results suggested that EIS was the most efficient straw return mode to increase TOC and improve soil structure and fertility.

The flavonoid biosynthetic pathway and flavonoid metabolites have been extensively studied because of their biological roles in plant and animal kingdoms. Flavonoid metabolites are involved in plant resistance, UV-protection, pollinator attraction and have antioxidant effects. Plant species synthesise a large number of secondary metabolites, including flavonoids, carotenoids and others. Flower colour is an important feature for marketing of the ornamental model plant gerbera (Gerbera hybrida). In gerbera, flavonoid metabolites accumulate in the adaxial epidermal layer of flower petals and lead to different flower colours and patterns. These metabolites consist of three subgroups, flavones, flavonols and anthocyanins in gerbera, which have also been used to characterize different cultivars. The cultivars show variation in flower colour according to their anthocyanin type. The acyanic gerbera cultivars have flavonoid profiles comparable to the cyanic cultivars, except for the synthesis and accumulation of specific anthocyanins. Metabolite profiles indicated that all analysed acyanic cultivars have a block in a late stage of the anthocyanin pathway. Ivory, a sport of the pelargonidin-cultivar Estelle, has white flowers. Ivory has flavones and flavonols, but no anthocyanin. Gene expression of all flavonoid pathway genes was similar in Estelle and Ivory. However, both cultivars have two different alleles encoding dihydroflavonol 4-reductase and in Ivory one of them (GDFR1-2) was found to have a point mutation resulting in inactivation of the encoded enzyme. Still, Ivory expresses the second allele (GDFR1-3) and accumulates active DFR enzyme. The cyanidin cultivar President expresses only the GDFR1-3 allele, but cannot synthesize pelargonidin. Therefore, GDFR1-2 contributes specifically to pelargonidin biosynthesis and GDFR1-3 to cyanidin biosynthesis. This could be explained by a coordinated biosynthesis of anthocyanins in multi-enzyme complexes, metabolons. Gerbera chalcone synthases (GCHSs) belong to the superfamily of Type III polyketide synthase enzymes. GCHS1, 3 and 4 have different contributions to the flavonoid pathway, according to the tissue specific and post-transcriptional regulation. RNA interference of CHS encoding genes was used in different gerbera cultivars to show that GCHS1 has the main contribution to anthocyanin accumulation in petal tissues. GCHS4 was strongly expressed in petals but did not lead to anthocyanin accumulation. Still, GCHS4 is expressed and encoded a functional enzyme in the vegetative tissues. Flavonoidit ovat kasvien fenolisia yhdisteitä, jotka voivat olla värittömiä (flavonit ja flavonolit) tai oranssin, punaisen tai sinisen sävyisiä pigmenttejä (antosyaanit). Flavonodit suojaavat kasvia UV-säteilyltä ja taudinaiheuttajilta, ja toisaalta houkuttelevat hyödyllisiä pölyttäjiä. Flavonoidit ovat ravinnossa tärkeitä antioksidantteja ja niiden biosynteesiä on tutkittu paljon. Tässä työssä tutkittiin koristekasvina tunnetun gerberan kukinnon flavonoidien kemiaa, entsymologiaa ja geeniekspressiota. Materiaalina käytettiin lajikkeita, jotka sisälsivät flavoneja (apigeniinia tai luteiinia), flavonoleja (kemferolia tai kversetiiniä) ja/tai antosyaaneja (pelargonidiineja tai syanidiineja). Punaisesta Estelle-lajikkeen sivuhaarana syntyneessä valkoisessa Ivory-lajikkeessa todettiin mutaatio antosyaanibiosynteesille tärkeässä DFR-entsyymiä koodaavassa geenissä. Toinen DFR-alleeli kuitenkin koodasi toimivaa entsyymiä, joka kasvissa ei johtanut pigmentin biosynteesiin vaikka geeni ilmeni. Samalla tavalla flavonoidireitin alkupäässä olevan CHS-entsyymin kohdalla todettiin, että kahdesta kukinnossa ilmenevästä muodosta vain toinen oli tärkeä kukinnon antosyaanien biosynteesille. Toinen vastasi lehtiruotiin muodostuvasta antosyaanista. Yhteenvetona voidaan todeta, että flavonodien biosynteesiä säädellään geberalla geenitoiminnan lisäksi myös proteiinitasolla.