An 8-week feeding trial was conducted to evaluate the effects of dietary fermented rapeseed meal (FRM), potassium iodide, and their interactions on growth performance, approximate composition, and antioxidant capacity in tilapia, Oreochromis niloticus (initial body weight: 3.50 ± 0.15 g). Six isonitrogenous and isolipidic diets from a 2 × 3 factorial design were formulated with two levels of FRM (25.8 and 51.6%) and three levels of potassium iodide (0, 6, and 12 mg/kg), respectively. The results indicated that dietary levels of FRM and iodine had no significant influence on the SR of tilapia but exerted significant effects on weight gain (WG), specific growth rate (SGR), feed intake (FI), hepatosomatic index, and viscerosomatic index. The WG, SGR, and FI of tilapia in the 51.6% FRM groups were significantly lower than those in other groups (p < 0.05), and iodine inclusion in the 51.6% FRM diet significantly enhanced WG, SGR, and FI of tilapia (p < 0.05). Dietary iodine significantly increased the whole-body and muscle lipid content in the tilapia (p < 0.05). The content of total bilirubin (T-Bil) and the activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the tilapia serum were significantly reduced by the inclusion of 6–12 mg/kg iodine in 51.6% FRM level (p < 0.05), and the serum total triiodothyronine content was significantly elevated by the supplementation of 12 mg/kg iodine (p < 0.05). Significant interactions between dietary FRM and iodine were found in serum T-Bil content and triglyceride and AST activity (p < 0.05). Dietary supplementation of iodine in high FRM diets (51.6%) significantly increased the activities of total superoxide dismutase (T-SOD), catalase (CAT), and total antioxidant capacity (T-AOC) and decreased the content of malondialdehyde (MDA) in the liver of tilapia (p < 0.05). The activity of T-SOD, CAT, and T-AOC and the content of MDA in the liver of tilapia significantly interacted with the levels of dietary FRM and iodine (p < 0.05). Furthermore, the liver cell structure was further ameliorated, and the liver health status was significantly enhanced in each iodine treatment group.
In recent years, N-heterocyclic carboxylate ligands have attracted much interest in the preparation of new coordination polymers since they contain N-atom donors, as well as O-atom donors, and have a rich variety of coordination modes which can lead to polymers with intriguing structures and interesting properties. A new two-dimensional coordination polymer, namely poly[[μ 3 -2,2′-(1,2-phenylene)bis(4-carboxy-1 H -imidazole-5-carboxylato)-κ 6 O 4 , N 3 , N 3′ , O 4′ : O 5 : O 5′ ]manganese(II)], [Mn(C 16 H 8 N 4 O 8 )] n or [Mn(H 4 Phbidc)] n , has been synthesized by the reaction of Mn(OAc) 2 ·4H 2 O (OAc is acetate) with 2,2′-(1,2-phenylene)bis(1 H -imidazole-4,5-dicarboxylic acid) (H 6 Phbidc) under solvothermal conditions. In the polymer, each Mn II ion is six-coordinated by two N atoms from one H 4 Phbidc 2− ligand and by four O atoms from three H 4 Phbidc 2− ligands, forming a significantly distorted octahedral MnN 2 O 4 coordination geometry. The Mn II ions are linked by hexadentate H 4 Phbidc 2− ligands, leading to a two-dimensional structure parallel to the ac plane. In the crystal, adjacent layers are further connected by N—H...O hydrogen bonds, forming a three-dimensional structure in the solid state.
Imidazole-4,5-dicarboxylic acid (H 3 IDC) and its derivatives are widely used in the preparation of new coordination polymers owing to their versatile bridging coordination modes and potential hydrogen-bonding donors and acceptors. A new one-dimensional coordination polymer, namely catena -poly[[diaquacadmium(II)]-μ 3 -2,2′-(1,2-phenylene)bis(1 H -imidazole-4,5-dicarboxylato)], [Cd(C 16 H 6 N 4 O 8 ) 0.5 (H 2 O) 2 ] n or [Cd(H 2 Phbidc) 1/2 (H 2 O) 2 ] n , has been synthesized by the reaction of Cd(OAc) 2 ·2H 2 O (OAc is acetate) with 2,2′-(1,2-phenylene)bis(1 H -imidazole-4,5-dicarboxylic acid) (H 6 Phbidc) under solvothermal conditions. In the polymer, one type of Cd ion (Cd1) is six-coordinated by two N atoms and two O atoms from one H 2 Phbidc 4− ligand and by two O atoms from two water molecules, forming a significantly distorted octahedral CdN 2 O 4 coordination geometry. In contrast, the other type of Cd ion (Cd2) is six-coordinated by two N atoms and two O atoms from two symmetry-related H 2 Phbidc 4− ligands and by two O atoms from two symmetry-related water molecules, leading to a more regular octahedral coordination geometry. The Cd1 and Cd2 ions are linked by H 2 Phbidc 4− ligands into a one-dimensional chain which runs parallel to the b axis. In the crystal, the one-dimensional chains are connected through hydrogen bonds, generating a two-dimensional layered structure parallel to the ab plane. Adjacent layers are further linked by hydrogen bonds, forming a three-dimensional structure in the solid state.
In the construction of coordination polymers, many factors can influence the formation of the final architectures, such as the nature of the metal centres, the organic ligands and the counter-anions. In the coordination polymer poly[aqua(μ-benzene-1,2-dicarboxylato-κ 4 O 1 , O 1′ : O 2 , O 2′ )[μ-2-(1 H -imidazol-1-ylmethyl)-6-methyl-1 H -benzimidazole-κ 2 N 2 : N 3 ]cadmium(II)], [Cd(C 12 H 12 N 4 )(C 8 H 4 O 4 )(H 2 O)] n or [Cd(immb)(1,2-bdic)(H 2 O)] n , each Cd II ion is seven-coordinated by two N atoms from two symmetry-related 2-(1 H -imidazol-1-ylmethyl)-6-methyl-1 H -benzimidazole (immb) ligands, by four O atoms from two symmetry-related benzene-1,2-dicarboxylate (1,2-bdic 2− ) ligands and by one water molecule, leading to a CdN 2 O 5 distorted pentagonal bipyramidal coordination environment. The immb and 1,2-bdic 2− ligands bridge Cd II ions and form a two-dimensional network structure. O—H...O and N—H...O hydrogen bonds stabilize the structure. In addition, the IR spectroscopic properties, PXRD patterns, thermogravimetric behaviour and fluorescence properties of the title polymer have been investigated.
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