Mechanical properties and acoustic emission characteristics of basalt fiber reinforced cemented silty sand subjected to freeze-thaw cycles.

Freeze-thaw (F-T) cycling poses a significant challenge in seasonally frozen zones, notably affecting the mechanical properties of soil, which is a critical consideration in subgrade engineering. Consequently, a series of unconfined compressive strength tests were conducted to evaluate the influence of various factors, including fiber content, fiber length, curing time, and F-T cycles on the unconfined compression strength (UCS) of fiber-reinforced cemented silty sand. In parallel, acoustic emission (AE) testing was conducted to assess the AE characteristic parameters (e.g., cumulative ring count, cumulative energy, energy, amplitude, RA, and AF) of the same material under F-T cycles, elucidating the progression of F-T-induced damage. The findings indicated that UCS initially increased and then declined as fiber content increased, with the optimal fiber content identified at 0.2%. UCS increased with prolonged curing time, while increases in fiber length and F-T cycles led to a reduction in UCS, which then stabilized after 6 to 10 cycles. Stable F-T cycles resulted in a strength loss of approximately 30% in fiber-reinforced cemented silty sand. Furthermore, AE characteristic parameters strongly correlated with the stages of damage. F-T damage was segmented into three stages using cumulative ring count and cumulative energy. An increase in cumulative ring count to 0.02 × 104 times and cumulative energy to 0.03 × 104 mv·µs marked the emergence of critical failure points. A sudden shift in AE amplitude indicated a transition in the damage stage, with an amplitude of 67 dB after 6 F-T cycles serving as an early warning of impending failure.

A hybrid technique combining intramedullary pinning with extramedullary plate fixation in unstable and comminuted radial head fractures following on-table reconstruction.

BACKGROUND: Management of comminuted radial fractures remains controversial. Currently, the emergence of on-table reconstruction technique has made fixation in comminuted radial head fractures more viable. However, the present study reported an intro-operative unstable displacement from the reconstructed radial head to the neck during plate fixation, characterized by a poor radiocapitellar contact and incongruity between the radial head and neck. A hybrid technique combining with intramedullary pining was performed in our study to restore the normal alignment and maintain the stability of fixation. Therefore, the purpose of this article aimed to prove the feasibility of unstable comminuted radial head fractures treated with the extramedullary plate and intramedullary pinning fixation using titanium elastic nails. METHODS: The clinical, functional and radiographic outcomes of the groups were compared during follow-up. The radiographic examination was conducted to evaluate the status of bone union, heterotopic ossification and post-traumatic arthritis. The functional assessment was performed to evaluate clinical effects, which included measurements of range of motion (ROM) in the elbow, Visual Analog Scale (VAS) score, Elbow Self-Assessment score (ESAS), Mayo Elbow Performance score (MEPS), and Disabilities of the Arm, Shoulder, and Hand (DASH)Outcome Measure score. RESULTS: Thirteen patients with unstable fractures were participated with an average follow-up of (38.6 ± 4.5) months for the experimental group and (32.0 ± 6.3) months for the control group, respectively. The functional outcomes in the experimental group, including MEPS and DASH, were significantly superior to the control group. However, no significant difference was observed in the elbow ROM and VAS score between two groups. In the last follow-up, one patient with post-traumatic arthritis rated as grades 1 and two with heterotopic ossifications were observed in the experimental group. In the control group, degenerative changes were observed in three cases (grade 1 in two cases and grade 2 in one case) and heterotopic ossifications rated as grade I were found in two patients. CONCLUSION: Collectively, intramedullary pinning with extramedullary plate fixation is feasible in unstable comminuted radial head fractures, which can be considered as a remedial surgery for on-table reconstruction technique.

Management of Open Calcaneal Fractures with Medial Wounds by One-Stage Sequential Reduction and Frame Structure Fixation Using Percutaneous Kirschner Wires.

OBJECTIVE: To assess the clinical outcomes of open calcaneal fractures with medial wounds treated with one-stage management, including early modern wound care, sequential reduction, and frame structure fixation using percutaneous Kirschner wires. METHODS: A total of 19 patients with open calcaneal fractures admitted to our hospital from May 2016 to March 2019 were selected in this study. Twelve type-II and seven type-IIIA medial open injuries were identified according to the classification of Gustilo and Anderson. Fractures were stratified by Sanders classification, including nine type-II fractures, seven type-III fractures, and three type-IV fractures. All patients accepted one-stage irrigation and debridement, sequential reduction of calcaneal fractures through the open medial wound, percutaneous Kirschner wire fixation, and primary closure of wounds covered with vacuum-assisted closure (VAC) device. The Bohler angle, the Gissane angle, and the width of the calcaneus were compared before and after surgery. The functional results were evaluated according to the Paley and Hall score system, visual analogue scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) ankle and hindfoot score, Maryland Foot Score, and related complications. RESULTS: The follow-up duration for all patients ranged from 14 to 28 months (mean, 22.7 months). The angle of Bohler and Giasane was increased from (-7.6° ± 15.0°) and (96.6° ± 7.6°) before surgery to (23.7° ± 6.1°) and (124.1° ± 7.1°) postoperatively (P < 0.05), respectively. Three cases of superficial infection and two cases of wound dehiscence were observed in our study, which were then successfully treated with wound debridement, VAC replacement, appropriate use of antibiotics, and delayed closure. The last follow-up revealed three cases of lateral wall expansion and six cases of mild-to-moderate subtalar arthritis based on the Paley and Hall scoring system. According to the AOFAS ankle and hindfoot score, one case showed excellent results, 14 cases exhibited good results, and four cases displayed fair results, with the mean of 80.7 ± 6.7 points (range, 70-90). The Maryland Foot Score revealed one case of excellent outcomes, nine cases of good outcomes, and nine cases of fair outcomes with an average of 76.8 ± 8.6 points (range, 62-90). The mean VAS for pain was 1.8 ± 1.5 (range, 0-5), and a total of 14 patients complained of mild-to-moderate pain when walking for a more extended period. Severe complications, such as deep infection, osteomyelitis, and soft tissue necrosis, were not observed during follow-up. CONCLUSIONS: Collectively, one-stage management allowed the direct restoration of calcaneal morphology with a minimal invasion of soft tissues in most open calcaneal fractures with medial wounds, and the functional outcomes were comparable to previous data.

IDTI Dyes for Fluoride Anion Chemosensors.

Fluoride anions play a key role in human health and chemical engineering, such as in organic synthesis and biological processes. The development of high-sensitivity naked-eye detection sensors for fluoride anions in organic solutions is crucial and challenging. In this study, (3Z,3'Z)-3,3'-[4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-s-indaceno(1,2-b:5,6-b')dithiophene]-2,7-diylbis(methan-1-yl-1-ylidene) bis(6-bromo-indolin-2-one) (IDTI) was designed and used as a fluoride chemosensor for the first time. IDTI is a highly sensitive fluoride sensor with a detection limit of as low as 1 × 10-7 M. In addition, upon the reaction of IDTI with fluoride anions in a tetrahydrofuran (THF) solution, color changes from red to yellow under ambient light and from purple to green under UV light were detectable by the naked eye. These studies indicate that IDTI is a promising fluoride chemosensor.

Electronic structures and spin topologies of gamma-picoliniumyl radicals. A study of the homolysis of N-methyl-gamma-picolinium and of benzo-, dibenzo-, and naphthoannulated analogs.

Radicals resulting from one-electron reduction of (N-methylpyridinium-4-yl) methyl esters have been reported to yield (N-methylpyridinium-4-yl) methyl radical, or N-methyl-gamma-picoliniumyl for short, by heterolytic cleavage of carboxylate. This new reaction could provide the foundation for a new structural class of bioreductively activated, hypoxia-selective antitumor agents. N-methyl-gamma-picoliniumyl radicals are likely to damage DNA by way of H-abstraction and it is of paramount significance to assess their H-abstraction capabilities. In this context, the benzylic C-H homolyses were studied of toluene (T), gamma-picoline (P, 4-methylpyridine), and N-methyl-gamma-picolinium (1c, 1,4-dimethylpyridinium). With a view to providing capacity for DNA intercalation the properties also were examined of the annulated derivatives 2c (1,4-dimethylquinolinium), 3c (9,10-dimethylacridinium), and 4c (1,4-dimethylbenzo[g]quinolinium). The benzylic C-H homolyses were studied with density functional theory (DFT), perturbation theory (up to MP4SDTQ), and configuration interaction methods (QCISD(T), CCSD(T)). Although there are many similarities between the results obtained here with DFT and CI theory, a number of significant differences occur and these are shown to be caused by methodological differences in the spin density distributions of the radicals. The quality of the wave functions is established by demonstration of internal consistencies and with reference to a number of observable quantities. The analysis of spin polarization emphasizes the need for a clear distinction between "electron delocalization" and "spin delocalization" in annulated radicals. Aside from their relevance for the rational design of new antitumor drugs, the conceptional insights presented here also will inform the understanding of ferromagnetic materials, of spin-based signaling processes, and of spin topologies in metalloenzymes.

Stabilities and Spin Distributions of Benzannulated Benzyl Radicals.

The effects have been studied of mono- and dibenzannulation of a benzyl radical with hybrid density functional theory (B3LYP) and quadratic configuration interaction theory (QCISD). Bond dissociation energies and enthalpies are reported that were determined at the common level QCISD/6-311G**//B3LYP/6-31G* for the benzylic C-H bonds of toluene 1H, the monobenzannulated polycyclic aromatic hydrocarbons (PAH) 1- and 2-methylnaphthalene 2H and 3H, the dibenzannulated PAHs 9-methylanthracene 4H and 9-methylphenanthrene 5H, and the model hydrocarbons 1-phenylpropene 6H and propene 7H. The conformational preferences and the symmetries of 1H-7H and of their corresponding radicals 1-7 have been determined. The analysis of the electron and spin density distributions of radicals 1-7 at the QCI level are reported, and these high-level data are discussed in comparison to results obtained with density functional theory and with an awareness of a general perception shaped by Hückel molecular orbital theory. The results show in a compelling fashion that electron and spin delocalization onto an annulated arene is not the decisive principle for stabilization of the benzyl radicals formed by homolysis of the methylated PAHs C10H7-CH3 and C14H9-CH3, and instead, the analysis of QCI spin density distributions suggests that spin delocalization onto annulated arenes is avoided as much as possible while spin polarization does occur to a significant extent.

(+/-)-1-Methyl-1,3,6-triphenyl-7-(2-phenylpropenyl)-1,2-dihydronaphthalene.

The crystal structure of the title compound, C38H32, presents a novel framework that combines the functionalities of a 1,6-diarene-substituted 1,2-dihydronaphthalene (DHN) with a 1,4-distyrylbenzene (DSB) to form a crossed bis-diarene. The lamellar crystal structure is held together by arene-arene interactions. While the orientations of the phenyl rings of the DSB units alternate within both the R and the S substructures, the homochiral substructures feature opposing polarity along the long axes of the DHN-based diarenes.