A b s t r a c k A simple method of approximating frequency Characteristics of composites in a form convenient for timedomain numerical modeling is proposed. The frequency characteristics can be obtained from experiment or calculations based ou the Maxwell Garnett mixing formalism. The resultant frequency characteristic might be of a complex shape corresponding to a Combination of a number of absorption peaks. The approximation is made by a series ofDebye-like terms using a genetic algorithm (GA). This leads to the necessity of taking a number of terms in the approximating series. Every term corresponds to its pole, i.e., the frequency where the maximum loss occurs. Some numerical examples are represented.

Background contextPedicle screw loosening is a common complication after spine surgeries. Traditionally, it was assessed by radiological approaches, both X-ray and CT (computed tomography) scan, while reports using mechanical method to study screw loosening after spine surgery are rare. The primary objective was to study the prevalent of pedicle screw loosening according to extraction torque during screw removal surgery and access the sensitivity and specificity of both X-ray and CT scan for diagnosing screw loosening. The second objective was to identify the risk factors for low extraction torque of pedicle screw that might lead to loosening.MethodsThirty-three patients who underwent pedicle screw removal surgery after at least 2 years from primary surgery were evaluated preoperatively for fixation stability by X-ray and CT scan. In total, 236 screws were taken out, and the extraction torque data was recorded and analyzed to identify the sensitivity and specificity of both imaging studies for screw loosening. Furthermore, risk factors that might contribute to low extraction torque were also studied.ResultsThe mean extraction torque of removed screws was 1.55 ± 1.00 Nm; a torque force of less than 1.02 Nm was used to define a screw as loosened. According to such criterion, the loosening rate was found to be 33%. X-ray had a sensitivity of 24% and a specificity of 98%, while CT scan had a sensitivity of 22% and a specificity of 96%. Extraction torque of pedicle screws inserted in fractured vertebrae was significantly lower than those in non-fractured vertebrae (p = 0.009); meanwhile, screws of non-fusion surgery had lower extraction torque when compared to those in fusion surgery (p = 0.001). BMD (bone mineral density) and age had low but significant linear relationship with screw extraction torque (p = 0.01, R2 = 0.304; p = 0.045, R2 = 0.123).ConclusionsOur findings showed that both X-ray and CT scan had high specificity for screw loosening detection, but their sensitivities were relatively low. Surgeons needed to be more cautious when assessing screw loosening merely according to radiological examination, and aware of that screws in fractured vertebrae or non-fusion surgery were vulnerable to loosening.

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The development of bifunction al molecules, which can enable targeted RNA degradation, targeted protein acetylation, or targeted protein degradation, remains a time-consuming process that requires tedious optimization. We propose a split-and-mix nanoplatform that serves as a self-adjustable platform capable of facile screening, programmable ligand ratios, self-optimized biomolecule spatial recognition, and multifunctional applications. Herein, we demonstrate the potential of our proposed nanoplatform by showcasing proteolysis-targeting chimeras (PROTACs), namely, split-and-mix PROTAC (SM-PROTAC). We highlight the scope of our platform through the targeted disruption of intracellular therapeutic targets involving ERα, CDK4/6, AR, MEK1/2, BRD2/4, BCR-ABL, etc. These studies confirm the effectiveness and universality of the SM-PROTAC platform for proximity-induced applications. This platform is programmable, with significant potential applications to biomolecule regulation, including the fields of epigenetics, gene editing, and biomolecule modification regulation.