Search Results (6)

As work continues unabated in the study of noncovalent bonding, particularly σ-hole bonds, new challenges have emerged as the participation of transition metals in interactions of this sort is fast becoming appreciated. While there are certain similarities with the halogen, chalcogen, etc, bonds, in which the main group elements participate, there are certain unique properties of these metal atoms that must be analyzed before a complete understanding can be attained. As one example, these atoms tend to act simultaneously as both electron donors and acceptors, a synergistic action that amplifies the overall bond strength. Ideas are expressed in this paper to hopefully guide future work in this exciting new arena. Full article

Noncovalent interactions involving metals as electron acceptors are continuously under investigation. The term “matere bond” has been proposed to identify noncovalent donor–acceptor interactions where elements of group 7 of the periodic table play the role of the electrophilic site. Most of the works on matere bonds involve rhenium atoms usually in +7 oxidation state. This work emphasizes for the first time their importance in technetium derivatives in several oxidation states (+7, +6, +5, and +3). The Cambridge Structural Database (CSD) in combination with density functional theory (DFT) calculations are used to demonstrate the structure directing role of matere bonds in X-ray structures, even involving anion⋯anion interactions. Further characterization of the matere bonds is provided using Molecular Electrostatic Potential (MEP) surface calculations, the “Quantum Theory of Atoms in Molecules” (QTAIM), and Natural Bond Orbital (NBO) analyses. It should be emphasized that some types of matere bonds reported herein have not been previously described in literature. Full article

The term matere bond has been recently used to refer to an attractive noncovalent interaction between any element of group 7 acting as an electrophile and any atom (or group of atoms) acting as a nucleophile. The utilization of metals such as σ-hole donors is starting to attract the attention of the scientific community. In this manuscript, a comparison between matere bonds and well-known σ-hole interactions (halogen and chalcogen bonds) is carried out using three X-ray structures, retrieved from the Cambridge structural database (CSD), and density functional theory calculations (DFT). The novelty of this work resides in the utilization of a neutral Re(VII) system as the matere bond donor and multivalent chalcogen and halogen donors. In fact, as far as our knowledge extends, the description of σ-hole interactions in Se(VI) is unprecedented in the literature. The σ-hole interactions in Re(VII), Se(VI) and Cl(VII) electron acceptors are analyzed and compared using several computational tools. Full article

Dura mater repair represents a final and crucial step in neurosurgery: an inadequate dural reconstruction determines dreadful consequences that significantly increase morbidity and mortality rates. Different dural substitutes have been used with suboptimal results. To overcome this issue, in previous studies, we proposed a laser-based approach to the bonding of porcine dura mater, evidencing the feasibility of the laser-assisted procedure. In this work, we present the optimization of this approach in ex vivo experiments performed on porcine dura mater. An 810-nm continuous-wave AlGaAs (Aluminium Gallium Arsenide) diode laser was used for welding Indocyanine Green-loaded patches (ICG patches) to the dura. The ICG-loaded patches were fabricated using chitosan, a resistant, pliable and stable in the physiological environment biopolymer; moreover, their absorption peak was very close to the laser emission wavelength. Histology, thermal imaging and leak pressure tests were used to evaluate the bonding effect. We demonstrated that the application of 3 watts (W), pulsed mode (T_on 30 ms, T_off 3.5 ms) laser light induces optimal welding of the ICG patch to the dura mater, ensuring an average fluid leakage pressure of 216 ± 105 mmHg, falling within the range of physiological parameters. This study demonstrated that the thermal effect is limited and spatially confined and that the laser bonding procedure can be used to close the dura mater. Our results showed the effectiveness of this approach and encourage further experiments in in vivo models. Full article

Unavailability of balanced nutrients in nutrient-deficient soils is the key reason in reduced yields of spring maize. After application to soil, most of the phosphorus (80–90%) is lost in the environment because of runoff losses and chemically bonding. So, this makes the phosphorus unavailable for plant use. However, soil microorganisms may provide a biological rescue system which is able to solubilize the soil-bound phosphorus (p). Keeping this in view, the present study is designed to meet the following objectives; (1) to improve physico-chemical properties of soil (e.g., soil water retention, soil enzyme activities), and (2) to improve growth and yield of spring maize (cv. Hybrid YSM-112) through the inoculation of phosphorus solubilization bacteria (PSB). A pot experiment was carried out with the following treatments; T1: control (uninoculated control, CT), T2: inoculation with PSB (Enterobacter sakazakii J129), T3: recommend level of NPK fertilizers (RNPK), T4: PSB + RNPK fertilizers, T5: rock phosphate (RP), T6: PSB + RP. Results showed that the addition of PSB together with RNPK improved the yield and yield-related characteristics of spring maize grown in sandy soil. Moreover, it also enhanced dry mater characteristics and maize grain quality. Soil fertility in the context of P-solubilization, soil organic acids, soil organic matter, enzyme activities, PSB colony, and rhizosphere moisture contents were significantly improved with PSB inoculation together with recommended dose of NPK fertilizers (RNPK) compared to PSB alone, rock phosphate (RP) alone, or PSB together with rock phosphate and control treatment. Maize digestibility attributes such as DM, CP, CF, EE (by 35%, 20%, 33%, and 28% respectively) and grain quality such as NPK, Mg, Ca, Fe, Mn, Cu, and Zn (by 88%, 92%, 71%, 68%, 78%, 90%, 83, 69%, 92%, 48%, and 90% respectively) were improved compared to control. In conclusion, improvement in maize crop yield and soil characteristics are more prominent and significant when RNPK is supplemented and inoculated. The present study suggests that PSB, together with RNPK, would improve the maize plant growth and soil fertility in sandy soil. Full article

Patients with paralysis, spinal cord injury, or amputated limbs could benefit from using brain–machine interface technology for communication and neurorehabilitation. In this study, a 32-channel three-dimensional (3D) multielectrode probe array was developed for the neural interface system of a brain–machine interface to monitor neural activity. A novel microassembly technique involving lead transfer was used to prevent misalignment in the bonding plane during the orthogonal assembly of the 3D multielectrode probe array. Standard microassembly and biopackaging processes were utilized to implement the proposed lead transfer technique. The maximum profile of the integrated 3D neural device was set to 0.50 mm above the pia mater to reduce trauma to brain cells. Benchtop tests characterized the electrical impedance of the neural device. A characterization test revealed that the impedance of the 3D multielectrode probe array was on average approximately 0.55 MΩ at a frequency of 1 KHz. Moreover, in vitro cytotoxicity tests verified the biocompatibility of the device. Subsequently, 3D multielectrode probe arrays were implanted in rats and exhibited the capability to record local field potentials and spike signals. Full article