Novel bioequivalent oral disintegrating tablet of aripiprazole prepared by direct compression technique with shortened disintegration time.

Herein, we aimed to formulate a novel oral disintegrating tablet (ODT) of aripiprazole (ARP) capable of rapid disintegration using a direct compression technique. Different ODTs were fabricated with directly compressible excipients, and their disintegration time, wettability (water absorption ratio and wetting time), and mechanical properties (hardness and friability) were evaluated. The optimized ODT comprised F-Melt® type C, Prosolv® SMCC HD90, and Na croscarmellose (10 mg of ARP in a 130 mg tablet). The ODT with 3.1-5.2 kp hardness exhibited rapid disintegration (14.1-17.2 sec), along with appropriate mechanical strength (friability < 0.24%). In a bioequivalent study in Korean healthy subjects (randomized, single-dose, two-period crossover design, n = 37), the novel ODT offered the equivalent pharmacokinetic profile to that of a conventional immediate release tablet (Otsuka, Abilify®, Japan), despite different disintegration and dissolution profiles. The 90% confidence intervals of the geometric mean test to reference ratios considering the area-under-the-curve and maximum plasma drug concentrations were 1.0306-11051 and 0.9448-1.1063, respectively, satisfying FDA regulatory criteria for bioequivalence. The novel ART ODT was physicochemically stable under the accelerated storage condition (40 °C, RH75%) for 24 weeks. Therefore, the novel ARP-loaded ODT is expected to be an alternative to oral ARP therapy, providing improved patient adherence.

Interfacial Properties and Melt Processability of Cellulose Acetate Propionate Composites by Melt Blending of Biofillers.

A series of eco-friendly biocomposites with improved mechanical properties and interfacial interaction were prepared by melt-mixing natural fibers using a cellulose acetate derivative as a polymer matrix and used to evaluate their mechanical, thermal, and morphological properties. The natural fiber used as a biofiller was pre-surface-treated by a refining process using alkali and natural enzymes to improve compatibility and increase interfacial bonding with biopolymer substrate. To increase the processability of the cellulose material, the raw material was plasticized and the composition prepared in the form of pellets in a twin-screw extruder by mixing with an additive before being molded through an injection process. For each composition, the interfacial bonding force between different materials was confirmed through morphology analysis and evaluation of mechanical and thermal properties. When biofillers and a viscosity modifier were used at the same time, the fabricated biocomposites had controllable crystallinity, stiffness, and elasticity and showed improved mechanical strength, such as tensile strength and flexural strength. These results indicated that interfacial properties could be increased through interfacial interactions between two different components due to appropriate surface treatment. In addition, it was confirmed that a composition having interfacial interaction, not a simple mixture, could be prepared by lowering both glass transition and melting temperature. The lowering of glass transition temperature increased the elasticity of the biocomposites, which have the potential advantage of easier melt processing when applied to various injection parts.

Mechanical Properties of Polypropylene-Based Flame Retardant Composites by Surface Modification of Flame Retardants.

A flame retardant refers to a substance that can be added to a material having the property of being efficiently combusted to improve the material physically and chemically. It should not affect the physical properties required for the final product. Halogen-based compounds are representative flame retardants with excellent flame retardancy. However, their use is limited due to restrictions on the use of chemicals introduced due to human safety. Magnesium hydroxide, one alternative material of halogen flame retardants, is widely used as an eco-friendly flame retardant. However, the most significant disadvantage is high load. To find a solution to this problem, many studies have been conducted by mixing magnesium hydroxide with other additives to create a synergistic effect. In this study, flame retardancy and mechanical properties of polypropylene-based flame retardant composites as a function of mixing surface-modified magnesium hydroxide with phosphorus-based flame retardants were investigated. All materials including PP, additives, and flame retardants were mixed using an extrusion process. Specimens were prepared by an injection process of the compound made after mixing. As a result of the evaluation of the mechanical properties by the modified flame retardant, the relational expression of the mechanical performance degradation as a function of the amount of addition was obtained, and the tensile (CBATS) and bending strength (CBABS) were performed on the amount of flame retardant added. The relational expression obtained in this study is considered to be a formula for predicting the strength reduction according to the addition amount of the modified flame retardant and can be used in industry. In addition, it was found that the addition amount of the modified flame retardant had a greater effect on the lowering of the bending strength.

On-Chip Microwave Frequency Combs in a Superconducting Nanoelectromechanical Device.

Nanomechanical resonances coupled to microwave cavities can be excited, measured, and controlled simultaneously using electromechanical back-action phenomena. Examples of these effects include sideband cooling and amplification, which are commonly described through linear equations of motion governed by an effective optomechanical Hamiltonian. However, this linear approximation is invalid when the pump-induced cavity microwave field is large enough to trigger optomechanical nonlinearities, resulting in phenomena like frequency combs. Here, we employ a niobium-based superconducting electromechanical device to explore the generation of microwave frequency combs. We observe the formation of combs around a microwave resonant frequency (3.78 GHz) with 8-MHz frequency spacing, equal to the mechanical resonant frequency. We investigate their dynamics for different optomechanical parameters, including detuning, pump powers, and cavity decay rates. Our experimental results show excellent agreement with numerical modeling. These electromechanical frequency combs can be beneficial in nanomechanical sensing applications that require precise electrical tracking of mechanical resonant frequencies.

Preoperative rotator cuff tendon integrity, tear size, and muscle atrophy and fatty infiltration are associated with structural outcomes of arthroscopic revision rotator cuff repair.

PURPOSE: A few studies have focused on factors predisposing to retear after arthroscopic revision rotator cuff repair (ARRCR). This study aimed to retrospectively evaluate (1) the structural and clinical outcomes of ARRCR and (2) pre- and intraoperative factors affecting the integrity of the rotator cuff (RC) tendon by focusing on preoperative RC tendon integrity, tear size, muscle hypotrophy and fatty infiltration. METHODS: Patients who underwent ARRCR between 2006 and 2016 were reviewed. Preoperative variables included demographic data, RC tendon integrity, tear size, and muscle hypotrophy and fatty infiltration on preoperative magnetic resonance imaging (MRI). Intraoperative variables included repair technique and completeness of repair. The visual analog scale for pain (PVAS), functional VAS (FVAS), American Shoulder and Elbow Surgeons scores, and shoulder range of motion (ROM) were assessed. Postoperative tendon integrity was evaluated using over 6-month follow-up MRI. Patients were classified into groups A (healed) and B (retear), and their variables were compared. RESULTS: Overall 65 patients with a mean follow-up of 49.5 ± 30.2 (range, 24.0-148.9) months were analyzed. Fifty-six of 65 (86.2%) patients underwent MRI at 9.1 ± 9.7 (range, 4.4-40.2) months after ARRCR, and 20 of 56 (35.7%) patients (group B) exhibited retear. Group A (36/56, 64.3%) showed higher functional scores and ROMs than group B at the final follow-up, with significant differences in the FVAS scores (Group A versus B: FVAS, 7.6 ± 1.8 versus 6.4 ± 1.9, p = 0.036). Intraoperative variables, including preoperative tendon integrity (p = 0.021), tear size (p = 0.007), supraspinatus and infraspinatus muscle hypotrophy and fatty infiltration (p < 0.001 and p = 0.046), and completeness of repair (p = 0.030), differed significantly between the groups. Multivariate analysis revealed that preoperative supraspinatus muscle hypotrophy and fatty infiltration were independent predisposing factors for retear after ARRCR [odds ratio = 7.5, 95% confidence interval (CI) 1.1-55.8, p = 0.048]. CONCLUSION: The retear was found in 20/56 patients (35.7%) after ARRCR for less than massive rotator cuff tears in this limited study population. Preoperative tendon integrity, tear size, supraspinatus and infraspinatus muscle hypotrophy and fatty infiltration, and completeness of repair was revealed to be associated with tendon integrity following ARRCR. Among them, preoperative supraspinatus muscle atrophy and fatty infiltration were the independent factors for retear after ARRCR, although generalization is limited. LEVEL OF EVIDENCE: IV.

Deep-learning framework and computer assisted fatty infiltration analysis for the supraspinatus muscle in MRI.

Occupation ratio and fatty infiltration are important parameters for evaluating patients with rotator cuff tears. We analyzed the occupation ratio using a deep-learning framework and studied the fatty infiltration of the supraspinatus muscle using an automated region-based Otsu thresholding technique. To calculate the amount of fatty infiltration of the supraspinatus muscle using an automated region-based Otsu thresholding technique. The mean Dice similarity coefficient, accuracy, sensitivity, specificity, and relative area difference for the segmented lesion, measuring the similarity of clinician assessment and that of a deep neural network, were 0.97, 99.84, 96.89, 99.92, and 0.07, respectively, for the supraspinatus fossa and 0.94, 99.89, 93.34, 99.95, and 2.03, respectively, for the supraspinatus muscle. The fatty infiltration measure using the Otsu thresholding method significantly differed among the Goutallier grades (Grade 0; 0.06, Grade 1; 4.68, Grade 2; 20.10, Grade 3; 42.86, Grade 4; 55.79, p < 0.0001). The occupation ratio and fatty infiltration using Otsu thresholding demonstrated a moderate negative correlation (ρ = - 0.75, p < 0.0001). This study included 240 randomly selected patients who underwent shoulder magnetic resonance imaging (MRI) from January 2015 to December 2016. We used a fully convolutional deep-learning algorithm to quantitatively detect the fossa and muscle regions by measuring the occupation ratio of the supraspinatus muscle. Fatty infiltration was objectively evaluated using the Otsu thresholding method. The proposed convolutional neural network exhibited fast and accurate segmentation of the supraspinatus muscle and fossa from shoulder MRI, allowing automatic calculation of the occupation ratio. Quantitative evaluation using a modified Otsu thresholding method can be used to calculate the proportion of fatty infiltration in the supraspinatus muscle. We expect that this will improve the efficiency and objectivity of diagnoses by quantifying the index used for shoulder MRI.

Superconducting Nanoelectromechanical Transducer Resilient to Magnetic Fields.

Nanoscale electromechanical coupling provides a unique route toward control of mechanical motions and microwave fields in superconducting cavity electromechanical devices. However, conventional devices composed of aluminum have presented severe constraints on their operating conditions due to the low superconducting critical temperature (1.2 K) and magnetic field (0.01 T) of aluminum. To enhance their potential in device applications, we fabricate a superconducting electromechanical device employing niobium and demonstrate a set of cavity electromechanical dynamics, including back-action cooling and amplification, and electromechanically induced reflection at 4.2 K and in strong magnetic fields up to 0.8 T. Niobium-based electromechanical transducers operating at this temperature could potentially be employed to realize compact, nonreciprocal microwave devices in place of conventional isolators and cryogenic amplifiers. Moreover, with their resilience to magnetic fields, niobium devices utilizing the electromechanical back-action effects could be used to study spin-phonon interactions for nanomechanical spin-sensing.

Effect of Preoperative Frozen Shoulder on Clinical Outcomes After Arthroscopic Rotator Cuff Repair.

BACKGROUND: A concomitant rotator cuff tear (RCT) with frozen shoulder is a common but challenging clinical scenario. The effect of frozen shoulder on clinical outcomes is open to discussion. PURPOSE/HYPOTHESIS: This study aimed to evaluate the effect of preoperative frozen shoulder on postoperative clinical outcomes of an RCT. We hypothesized that the treatment results of an RCT concomitant with preoperative frozen shoulder would be comparable with those of an isolated RCT. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 212 patients were divided into 2 groups: 154 in the non-frozen shoulder (NFS) group and 58 in the preoperative frozen shoulder (FS) group. All patients underwent a thorough preoperative evaluation that included range of motion (ROM) and the pain visual analog scale, functional visual analog scale, Constant score, and American Shoulder and Elbow Surgeons (ASES) score. The same evaluation was performed at 6 months and 1 and 2 years postoperatively. The healing status of the repaired RCT of all patients was evaluated by postoperative magnetic resonance imaging. RESULTS: The FS group showed statistically significantly worse functional outcomes than the NFS group at 6 months and 1 year postoperatively (P < .05). At 2 years postoperatively, active assisted ROM was equivalent between the groups, although the ASES and Constant scores were significantly lower for the FS group (P < .033 and P < .001, respectively). The retear rates were 5.3% and 12.3% for the FS and NFS groups, respectively (P = .013). CONCLUSION: Preoperative frozen shoulder positively affected rotator cuff healing but negatively affected most functional outcomes, including ROM, at 6 months and 1 year postoperatively. At 2 years after surgery, there was no significant difference in active motion, but outcome scores remained lower in the FS group. For patients with preoperative frozen shoulder, a delay in surgery for additional physical therapy might not be necessary. The retear rate for the NFS group was more than double that for the FS group in the current study, which indicates that surgery for an RCT combined with frozen shoulder might provide better results in the long term because of an intact, healed rotator cuff.

First Observation of Ferroelectricity in ∼1 nm Ultrathin Semiconducting BaTiO3 Films.

The requirements of multifunctionality in thin-film systems have led to the discovery of unique physical properties and degrees of freedom, which exist only in film forms. With progress in growth techniques, one can decrease the film thickness to the scale of a few nanometers (∼nm), where its unique physical properties are still pronounced. Among advanced ultrathin film systems, ferroelectrics have generated tremendous interest. As a prototype ferroelectric, the electrical properties of BaTiO3 (BTO) films have been extensively studied, and it has been theoretically predicted that ferroelectricity sustains down to ∼nm thick films. However, efforts toward determining the minimum thickness for ferroelectric films have been hindered by practical issues surrounding large leakage currents. In this study, we used ∼nm thick BTO films, exhibiting semiconducting characteristics, grown on a LaAlO3/SrTiO3 (LAO/STO) heterostructure. In particular, we utilized two-dimensional electron gas at the LAO/STO heterointerface as the bottom electrode in these capacitor junctions. We demonstrate that the BTO film exhibits ferroelectricity at room temperature, even when it is only ∼2 unit-cells thick, and the total thickness of the capacitor junction can be reduced to less than ∼4 nm. Observation of ferroelectricity in ultrathin semiconducting films and the resulting shrunken capacitor thickness will expand the applicability of ferroelectrics in the next generation of functional devices.

Does creating a trough on the anterior glenoid rim make a difference in Arthroscopic Bankart repair using suture anchors? A mid-term follow-up retrospective study.

PURPOSE: Creating a trough on the anterior glenoid rim is one of the methods used for arthroscopic Bankart repair with suture anchors. The purpose of this study was to analyze clinical and radiological outcomes of arthroscopic Bankart repair with suture anchors; to compare between the outcomes of surgical procedures with and without trough. METHODS: Clinical and radiological outcomes were evaluated for 116 patients who underwent arthroscopic Bankart repair at our institute from 2005 to 2011. The mean follow-up was 5.2 years (range, 2-8.8 years). All data were divided into trough group (n = 62) and non-trough group (n = 71). Clinical and functional outcomes were assessed pre- and postoperatively as range of motion (ROM), pain on the visual analog scale (p-VAS), function on the visual analog scale (f-VAS), and Rowe score. Radiological outcomes were also evaluated. RESULTS: The overall postoperative clinical and functional outcomes improved significantly (P < .001). A total of 8 patients (6.8%) showed recurrent instability. Radiologic findings showed mild arthritis in 27 cases (23.1%), moderate arthritis in 6 cases (5.1%), and no severe arthritis. 32 patients showed anterior apprehension after surgery, and 22 out of those 32 patients were from non-trough group. However, no significant difference between the trough and non-trough groups was found with respect to clinical and functional outcomes (P > .05). CONCLUSION: The additional procedure of creating a trough did not improve clinical outcomes in terms of frank dislocation; however, at the final follow-up, patients with the trough showed less anterior apprehension. Overall, arthroscopic Bankart repair using suture anchors had relatively good clinical outcome, with a redislocation rate of 6.8%. LEVEL OF EVIDENCE: Level III, Case series.

A Comparative Study to Evaluate the Risk Factors for Medium-Sized Rotator Cuff Tear in Patients Younger Than 50 Years of Age.

PURPOSE: The purpose of this study was to evaluate preoperative and intraoperative factors associated with rotator cuff tears (RCTs) among patients younger than 50 years and to compare arthroscopic rotator cuff repair (RCR) results in patients younger than 50 years (group A) and patients older than 70 years (group B). We also analyzed the results after arthroscopic RCR in these 2 age groups. METHODS: Data were collected from 56 patients allocated to group A and 55 patients allocated to group B who had medium-sized RCTs and had undergone arthroscopic RCR between January 2006 and August 2015. Preoperative variables included demographic data, radiologic data, and surgical procedure. We evaluated fatty degeneration on preoperative magnetic resonance imaging (MRI) and intraoperative variables, including concomitant subscapularis repair, as well as repair technique. Pain visual analog scale, functional visual analog scale, American Shoulder and Elbow Surgeons, and Constant scores were documented to compare functional results in each age group. Postoperative MRI scans were conducted to evaluate the retear rate after RCR after a mean postoperative duration of 5.4 months (range, 2-48 months). RESULTS: Multivariate regression analysis showed acute-on-chronic injury and a history of hypertension were independent factors for differentiation of the groups. Stepwise regression analysis found sex, hypertension, and fatty infiltration of the supraspinatus and infraspinatus to be comparable factors for each group. All patients showed improved results after arthroscopic RCR, but there was no difference between the 2 groups in functional outcomes. However, cuff retears on postoperative MRI scans were found in only 3.9% of the patients in group A versus 16% of the patients in group B. CONCLUSIONS: The results of this study showed that sex, acute-on-chronic injury, and preoperative fatty infiltration of the rotator cuff were significant factors affecting medium-sized RCTs in patients younger than 50 years. In addition, there were no significant differences in functional outcomes after arthroscopic RCR in both groups at 2 years, but postoperative MRI showed a lower retear rate in group A. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Evaluation of risk factors for irreparable rotator cuff tear in patients older than age 70 including evaluation of radiologic factors of the shoulder.

BACKGROUND: Rotator cuff tears (RCTs) are generally considered to occur at the age of 40 to 50, but some becomes massive tears at the age of 60 to 70 if neglected. This study evaluated preoperative factors affecting tear size and reparability of rotator cuffs based on magnetic resonance imaging findings among patients older than age 70. METHODS: We identified 270 patients with full-thickness RCTs (175 reparable tears, group A; 95 irreparable tears, group B) that were confirmed with magnetic resonance imaging findings from January 2009 to March 2016. Irreparable tear was identified if all of the following criteria were met: (1) a large to massive RCT based on the DeOrio and Cofield classification, (2) sum of preoperative global fatty degeneration index of the supraspinatus and infraspinatus ≥6, and (3) positive tangent sign. Preoperative variables included demographic data, medical history, and radiologic data. Acromial index, critical shoulder angle, and acromiohumeral interval (AHI) were evaluated to investigate the relationship between anatomic factors and reparability of RCT. RESULTS: Stepwise multivariated regression analysis revealed older age, longer symptom duration, longer duration of overhead sports activity, lower preoperative forward elevation of the shoulder joint, and shorter AHI as risk factors for irreparable RCTs. CONCLUSIONS: This study suggests that older age at surgery, longer duration of symptoms, longer duration of overhead sports activity, lower preoperative forward elevation of the shoulder joint, and shorter AHI are independent risk factors for irreparable RCT.

Broadband Surface Plasmon Lasing in One-dimensional Metallic Gratings on Semiconductor.

We report surface plasmon (SP) lasing in metal/semiconductor nanostructures, where one-dimensional periodic silver slit gratings are placed on top of an InGaAsP layer. The SP nature of the lasing is confirmed from the emission wavelength governed by the grating period, polarization analysis, spatial coherence, and comparison with the linear transmission. The excellent performance of the device as an SP source is demonstrated by its tunable emission in the 400-nm-wide telecom wavelength band at room temperature. We show that the stimulated emission enhanced by the Purcell effect enables successful SP lasing at high energies above the gap energy of the gain. We also discuss the dependence of the lasing efficiency on temperature, grating dimension, and type of metal.

Factors that Influence Reduction Loss in Proximal Humerus Fracture Surgery.

OBJECTIVES: This study was performed to identify the risk factors for reduction loss after locking plate fixation of proximal humerus fractures. DESIGN: Retrospective study. SETTING: University trauma center. PATIENTS AND INTERVENTION: We retrospectively evaluated 252 patients who had been surgically treated for proximal humeral fractures with locking plates between January 2004 and December 2011. MAIN OUTCOME MEASUREMENTS: Charts and standardized x-rays (true anteroposterior and axillary lateral views) were used to evaluate the Neer and AO OTA fracture types, initial neck-shaft angle (NSA, varus displacement), medial comminution, postoperative NSA (reduction adequacy), medial support restoration, healing progress, reduction loss, and implant-related problems immediately after surgery and at 2 weeks, 1 month, 3 months, 6 months, 9 months, and at least 1 year after surgery. Reduction loss was defined as (1) ≥10 of angulation in any direction, (2) ≥5 mm of height loss of the humeral head from the plate, and (3) fixation failure. RESULTS: Reduction loss occurred in 6.7% (17 of 252) of cases; revision surgeries were performed in all cases. Univariable logistic regression analysis revealed that older age (P = 0.023), osteoporosis (P = 0.001), varus displacement (P = 0.001), medial comminution (P = 0.001), reduction adequacy (P = 0.036), and insufficient medial support (P = 0.001) had significant correlations with reduction loss. CONCLUSIONS: Multivariable regression analysis revealed that osteoporosis (less than -2.5 bone mineral density, P = 0.015), displaced varus fracture (less than 110° of NSA, P = 0.025), medial comminution (more than 1 fragment, P = 0.018), and insufficient medial support (no cortical or screw support, P = 0.001) were independent risk factors for reduction loss in the proximal humerus fractures surgery. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Effect of titanium dioxide nanoparticles on gamma-ray treatment of phenol in different matrices: implications in toxicity toward Daphnia magna.

Gamma-ray treatment of phenol was studied in terms of both chemical degradation and toxicological change. About 90% of phenol (5.0 × 10(-4) M) in ultrapure water (UW) was eliminated by gamma-irradiation at a dose of 10 kGy, but acute toxicity was dramatically increased, particularly for dose of 1 kGy, due to the formation of more toxic by-products such as hydroquinone, benzoquinone, resorcinol and catechol. The addition of TiO(2) nanoparticles had little effect on the removal of phenol in UW, but substantially enhanced the mineralization of phenol compared with gamma-irradiation alone. Additionally, degradation of phenol by gamma-irradiation was inhibited in a wastewater effluent (WE) matrix, likely due to the presence of dissolved organic carbon (22.06 mg L(-1)). Furthermore, lower concentrations of toxic by-products were generated both in WE and in the presence of TiO(2) nanoparticles, resulting in reduction of toxicity increase by gamma-irradiation. Meanwhile, the toxicity of gamma-ray treated phenol in WE was well estimated with simple summation of individual toxicity of phenol and by-products (R (2) = 0.9678).

Facile synthesis of 2-O-iodoacetyl protected glycosyl iodides: useful precursors of 1-->2-linked 1,2-trans-glycosides.

The preparation and utilization of novel iodide glycosyl donors, 2-O-iodoacetyl-glycopyranosyl iodides, is described. The mechanism for the reaction of iodine with carbohydrate cyclic ketene acetal was investigated through low-temperature NMR experiments. 2-O-Iodoacetyl-glycopyranosyl iodides can serve as effective glycosyl donors giving 2-O-iodoacetyl 1,2-trans-glycosides in high yields and excellent stereoselectivities. The 2-O-iodoacetyl group was removed selectively with thiourea to afford 2-hydroxy 1,2-trans-glycosides in high yield without affecting other protecting groups and anomeric configurations.

Toxicity identification in metal plating effluent: implications in establishing effluent discharge limits using bioassays in Korea.

Because of complexity and diversity of toxicants in effluent, chemical analysis alone gives very limited information on identifying toxic chemicals to test organisms. Toxicity identification evaluation (TIE) techniques have been widely used to identify toxicants in various samples including industrial wastewater as well as natural waters. In response to new regulation for effluent discharge in Korea, which will be effective from 2011, a necessity of studies emerges that investigates toxicity levels in industrial effluents. This work was a preliminary study examining toxicity levels in effluent from one metal plating factory using Daphnia magna (48 h immobility) and identifying toxicity-causing substances. Toxicity tests showed variability on different sampling occasions and the results of TIE methods indicated that both organic compounds and metals contributed to the observed toxicity in metal plating effluent. Further studies are necessary to help reduce effluent toxicity especially from direct dischargers, who will have to comply with the new regulation.

Synchronized oscillation in coupled nanomechanical oscillators.

We report measurements of synchronization in two nanomechanical beam oscillators coupled by a mechanical element. We charted multiple regions of frequency entrainment or synchronization by their corresponding Arnold's tongue diagrams as the oscillator was driven at subharmonic and rational commensurate frequencies. Demonstration of multiple synchronized regions could be fundamentally important to neurocomputing with mechanical oscillator networks and nanomechanical signal processing for microwave communication.

Intramolecular ionic Diels-Alder reactions of alpha-acetylenic acetals.

The intramolecular ionic Diels-Alder reaction of alpha-acetylenic acetals as a precursor of the propargyl cation has been investigated in the presence of Lewis acids and in protic acids. The reaction of diene-tethered alpha-acetylenic acetals (1-2) with formic acid yielded the regioselective intramolecular ionic Diels-Alder reaction products, bicyclodienal (9) and bicyclodienone (11) derivatives, in good yields.