Crossover Experiment Research Articles

NiH-catalyzed anti-Markovnikov hydroamidation of unactivated alkenes with 1,4,2-dioxazol-5-ones for the direct synthesis of N-alkyl amides

The addition of a nitrogen-based functional group to alkenes via a direct catalytic method is an attractive way of synthesizing value-added amides. The regioselective hydroamidation of unactivated alkenes is considered one of the easiest ways to achieve this goal. Herein, we report the NiH-catalyzed anti-Markovnikov intermolecular hydroamidation of unactivated alkenes enabled by using 2,9-dibutylphenathroline (diBuphen) as the ligand. This protocol provides a platform for the direct synthesis of over 90 structurally diverse N-alkyl amides using dioxazolones, which can be easily derived from abundant carboxylic acid feedstocks. This method succeeds for both terminal and internal unactivated alkenes and some natural products. Mechanistic studies including DFT calculations reveal an initial reversible insertion/elimination of the [NiH] to the alkene, followed by the irreversible amidation to furnish the N-alkyl amides. By crossover experiments and deuterium labeling studies, the observed anti-Markovnikov regioselectivities are suggested to be controlled by the sterical environment of the coupling reaction.

Dose-response relationship between iTBS and prefrontal activation during executive functioning: A fNIRS study.

Intermittent theta-burst stimulation (iTBS) is a non-invasive brain stimulation paradigm that has demonstrated promising therapeutic benefits for a variety of neuropsychiatric disorders. It has recently garnered widespread favor among researchers and clinicians, owing to its comparable potentiation effects as conventional high-frequency repetitive transcranial magnetic stimulation (rTMS), but administered in a much shorter time frame. However, there is still a lack of agreement over the optimal stimulation intensity, particularly when targeting the prefrontal regions. The objective of this study was to systematically investigate the influence of different stimulation intensities of iTBS, applied over the left dorsolateral prefrontal cortex (DLPFC), on brain activity and executive function in healthy adults. Twenty young healthy adults were enrolled in this randomized cross-over experiment. All participants received a single session iTBS over the left DLPFC at intensities of 50, 70, or 100% of their individual resting motor threshold (RMT), each on separate visits. Functional near-infrared spectroscopy (fNIRS) was used to measure changes of hemoglobin concentrations in prefrontal areas during the verbal fluency task (VFT) before and after stimulation. After stimulation, iTBS to the left DLPFC with 70% RMT maintained the concentration change of oxyhemoglobin (HbO) in the target area during the VFT. In contrast, 50% [t (17) = 2.203, P = 0.042, d = 0.523] and 100% iTBS [t (17) = 2.947, P = 0.009, d = 0.547] significantly decreased change of HbO concentration, indicating an inverse U-shape relationship between stimulation intensity and prefrontal hemodynamic response in healthy young adults. Notably, improved VFT performance was only observed after 70% RMT stimulation [t (17) = 2.511, P = 0.022, d = 0.592]. Moreover, a significant positive correlation was observed between task performance and the difference in HbO concentration change in the targeted area after 70% RMT stimulation (r = 0.496, P = 0.036) but not after 50 or 100% RMT stimulation. The linear relationship between stimulation intensity and behavioral outcomes reported in previous conventional rTMS studies may not be translated to iTBS. Instead, iTBS at 70% RMT may be more efficacious than 100% RMT.

Influence of encapsulated pepper on ruminal fermentation, nutrient digestibility, and performance in dairy cows

The aim of this study was to evaluate the effects of a feed additive containing encapsulated pepper on total-tract apparent nutrient digestibility, sorting index, ruminal fermentation, milk yield and composition, serum concentrations of urea-N and glucose, purine derivative excretion, and N utilization efficiency in dairy cows. Twenty-two Holstein cows (182 ± 86.3 days in milk, 35.4 ± 4.85 kg/d milk yield), of which 4 were rumen cannulated, were used in a crossover design experiment with 21-d periods (14 days allowed to treatment adaptation and 7 days for sampling). Cows were blocked according to parity, days in milk, and milk yield and randomly assigned to the following treatments: Control (CON), or 1.5 g/d (CAP) of a feed additive containing encapsulated pepper (Capcin; NutriQuest, Campinas, Brazil) added to the concentrate along with minerals. Data were analyzed using the mixed procedure of SAS modeling the fixed effects of treatment, period, and the random effect of animal. Ruminal fermentation data were analyzed as repeated measurements adding the fixed effect of time and its interaction with treatments to the previous model. No differences in intake of dry matter or nutrients were detected. Sorting for feed particles between 19 and 8 mm size was greater in cows fed CAP compared to CON (1.000 and 0.992 kg/kg, respectively). Feeding CAP had no effects on digestibility of dry matter, crude protein, ether extract, or neutral detergent fiber. Nor treatment or interaction effect between treatment and time were observed for ruminal pH, NH3N concentration, or short-chain fatty acids concentration. Yields of milk (35.3 vs 34.3 kg/d) and fat-corrected milk (37.4 vs 36.0 kg/d) were greater for cows under CAP treatment compared to CON. Yield of milk solids (fat, protein, and lactose) was increased when feeding CAP. Milk fat concentration tended to be greater in cows fed CAP than those in CON group (39.5 vs 38.3 g/kg, respectively). Feed efficiency (fat-corrected milk ÷ dry matter intake) tended to be greater in cows fed CAP than CON-cows (1.45 vs 1.40, respectively). Serum concentrations of urea-N and glucose were similar between treatment groups. Feeding CAP did not alter purine derivative excretion (allantoin in urine and milk, and uric acid in urine), as well as the nitrogen excreted (g/g N intake) through feces, milk, or urine. In conclusion, feeding CAP at 1.5 g/d improved performance without altering nutrient digestibility, ruminal fermentation, excretion of purine derivatives, or efficiency of nitrogen utilization in dairy cows.

The need for metrics to measure progress on racial equity in global public health and medicine

The need for metrics to measure progress on racial equity in global public health and medicine

Resolving the Mechanistic Complexity in Triarylborane-Induced Conjugate Additions

Previous studies have shown that the catalytically active species in the Lewis acid-catalyzed addition reactions of allyl silanes or silyl enol ethers to carbonyl compounds or Michael acceptors are often silylium-carbonyl adducts rather than the adducts of the carbonyl group with the Lewis acid used for the induction of the reaction. Indirect evidence for such catalyst variations has so far been derived from double-label crossover experiments and comparisons of absolute reaction rates. We have now performed a detailed investigation on the kinetics and mechanism of the triarylborane-initiated conjugate addition reactions of allylsilanes and silyl enol ethers to α,β-unsaturated carbonyl compounds. NMR spectroscopic monitoring of such reactions gave rise to sigmoidal kinetic profiles, allowing us to directly follow the change of the catalytically active Lewis acid from triarylboranes in the induction period to silylium ions during the main part of the reaction. Crossover experiments and the isolation of four- and five-membered cyclic intramolecular trapping products provided further insight into the mechanism. DFT calculations of various mechanistic variants and kinetic modeling elucidated the operation of a complex reaction network, which rationalizes the experimental observations.

Acute effects of caffeinated chewing gum on basketball performance in elite female players

Background: To date, no study has investigated the effects of acute intake of caffeinated chewing gum in female basketball players. Methods: Nine elite female basketball players participated in a randomized crossover placebo-controlled double-blind experiment. All athletes participated in two identical experimental trials 15 minutes after ingestion of (i) chewing gum containing 150 mg of caffeine (i.e.~2.3 0.2 mg/kg of caffeine) or (ii) non-caffeinated chewing gum with an inert substance to produce a placebo. After the ingestion of the gum, the athletes performed the following tests: (i) a sprint test (0-20 m), (ii) agility T-test, (iii) isometric handgrip strength test, (iv) countermovement jump test, (v) free throw test, and (vi) three-point shot test. Results: No significant differences were observed in any physical or skill-based tests (p > 0.05 for all). However, the effect size in the sprint and agility T-Test, jump height test, and free-throw test was higher in the caffeine conditions, with effect sizes of small or moderate magnitude (ES = 0.31 – 0.64) over the placebo. Conclusion: From a practical perspective, the benefits of caffeinated chewing gum are minor, at least in elite athletes with a mild level of caffeine consumption.

Effects of poultry by-products inclusion in dry food on nutrient digestibility and fecal quality in Beagle dogs.

Animal by-product meals show large variability in diet digestibility. This study aimed to provide information on including bone protein meal (BPM) or feather meal (FM) in extruded dog diets with regard to digestibility and fecal characteristics in two trials. In the first trial, compared to the control (BPM0), 6, 12, and 24% of the basic diets were replaced by BPM (BPM6, BPM12, and BPM24, respectively). In the second trial, in comparison to the control (FM0), 5, 10, and 20% of the basic diets were replaced by FM (FM5, FM10, and FM20, respectively). In both trials, six Beagle dogs (BW 17.3±2.14 and 18.1±2.04 kg for trials 1 and 2, respectively) participated in a crossover experiment design. Five days were used as wash-out before each experimental period for each trial. The fecal consistency scores were based on a 5-point scale (1 = very hard, 2 = solid, well formed "optimum", and 5 = watery diarrhea). In the first trial, results showed that the apparent digestibility of dry matter, crude protein, and crude fat was significantly lower for dogs fed BPM6 compared to those fed BPM24. There was a lower number of dogs with a fecal consistency score value > 2 (16.7%) among those fed BPM6 (median = 2, Interquartile range (IQR) = 0) compared to those fed BPM24 (83.3%). The fecal dry matter content was significantly (p < 0.05) the highest (39.4%±2.15) for dogs fed BPM6. In the second trial, the data revealed that dogs fed FM0 had significantly (p < 0.05) the highest organic matter digestibility (87.2%±1.05), while dogs fed FM20 had significantly (p < 0.05) the lowest crude fat digestibility (95.0%±0.95). Inclusion of FM at 10% or 20% in the diet decreased fecal dry matter significantly (29.0%±2.10 and 27.9%±2.46, respectively) compared to those animals offered FM0 (31.1%±2.56). Among those dogs fed FM0 and FM5, there was a lower significant number of dogs with a fecal score value > 2 (16.7% and 16.7%, respectively; p < 0.05). While the fecal score was significantly a higher (median = 4, IQR = 0) for dogs fed FM20. Including FM at any level in the diet resulted in significantly higher levels of iso-butyric and iso-valeric acids compared to FM0. These findings in both trials suggest that apparent crude protein digestibility was not affected when diets containing BPM up to 24% and FM up to 20% were offered, but fecal quality was reduced.

Characterization of the Binding Behavior of Specific Cobalt and Nickel Ion-Binding Peptides Identified by Phage Surface Display

In recent years, the application focus of phage surface display (PSD) technology has been extended to the identification of metal ion-selective peptides. In previous studies, two phage clones—a nickel-binding one with the peptide motif CNAKHHPRCGGG and a cobalt-binding one with the peptide motif CTQMLGQLCGGG—were isolated, and their binding ability to metal-loaded NTA agarose beads was investigated. Here, the free cyclic peptides are characterized by UV/VIS spectroscopy with respect to their binding capacity for the respective target ion and in crossover experiments for the other ion by isothermal titration calorimetry (ITC) in different buffer systems. This revealed differences in selectivity and affinity. The cobalt-specific peptide is very sensitive to different buffers; it has a 20-fold higher affinity for cobalt and nickel under suitable conditions. The nickel-specific peptide binds more moderately and robustly in different buffers but only selectively to nickel.

The Effects of Acute Cannabis With and Without Cannabidiol on Neural Reward Anticipation in Adults and Adolescents

BackgroundAdolescents may respond differently to cannabis than adults, yet no previous functional magnetic resonance imaging study has examined acute cannabis effects in this age group. In this study, we investigated the neural correlates of reward anticipation after acute exposure to cannabis in adolescents and adults. MethodsThis was a double-blind, placebo-controlled, randomized, crossover experiment. Forty-seven adolescents (n = 24, 12 females, ages 16–17 years) and adults (n = 23, 11 females, ages 26–29 years) matched on cannabis use frequency (0.5–3 days/week) completed the Monetary Incentive Delay task during functional magnetic resonance imaging after inhaling cannabis with 0.107 mg/kg Δ⁹-tetrahydrocannabinol ("THC") (8 mg THC for a 75-kg person) or with THC plus 0.320 mg/kg cannabidiol ("THC+CBD") (24 mg CBD for a 75-kg person), or placebo cannabis. We investigated reward anticipation activity with whole-brain analyses and region of interest analyses in the right and left ventral striatum, right and left anterior cingulate cortex, and right insula. ResultsTHC reduced anticipation activity compared with placebo in the right (p = .005, d= 0.49) and left (p = .003, d = 0.50) ventral striatum and the right insula (p = .01, d = 0.42). THC+CBD reduced activity compared with placebo in the right ventral striatum (p = .01, d = 0.41) and right insula (p = .002, d = 0.49). There were no differences between "THC" and "THC+CBD" conditions and no significant drug by age group interaction effect, supported by Bayesian analyses. There were no significant effects in the whole-brain analyses. ConclusionsIn weekly cannabis users, cannabis suppresses the brain’s anticipatory reward response to money, and CBD does not modulate this effect. Furthermore, the adolescent reward circuitry is not differentially sensitive to acute effects of cannabis on reward anticipation.

Solvent Modification of the Structures and Magnetic Properties of a Series of Dysprosium(III) Single-Molecule Magnets.

Solvent effects on the structures and magnetic properties of single-molecule magnets (SMMs) have been of great interest for modification of the SMMs using chemical modulation. By systematically varying the reaction solvents (MeOH, ethanol, n-propanol, and n-butanol), we have successfully synthesized a series of DyIII-H4daps complexes (H4daps = N',N‴-[(1E,1'E)-pyridine-2,6-diylbis(ethan-1-yl-1-ylidene)]bis(2-hydroxybenzohydrazide), including two binuclear compounds, [Dy2(H2daps)2(MeOH)4(H2O)2](CF3SO3)2·0.5MeOH (1MeOH) and [Dy2(H2daps)3(EtOH)2]·2EtOH·Et2O (2EtOH), and two mononuclear compounds, [Dy(H4daps)2](CF3SO3)3·n-PrOH (3PrOH) and [Dy(H4daps)(CF3SO3)3(n-BuOH)]·0.5Et2O (4BuOH). Using different solvents, the ligand-to-metal ratios can be adjusted from 1:1 in 1MeOH and 4BuOH to 3:2 in 2EtOH and 2:1 in 3PrOH. Through the solvent crossover experiments, the role of the solvents and the conditions to form these complexes were carefully studied. The size of the different alcohols, their coordination ability to the DyIII center, and the solubility of the complexes in these alcohols might affect the assembly process and lead to modification of the structures and magnetic properties of these DyIII-H4daps complexes. Magnetic studies revealed that these four complexes all exhibit slow magnetic relaxation under a zero or an applied direct-current field, with an energy barrier of about 100 K for the binuclear compound 1MeOH. In combination with theoretical calculations, the magnetic-structure relationship of these four compounds has been analyzed. This work demonstrates the crucial role of different solvent molecules in the fine-tuning of the structures and magnetic performances of different lanthanide complexes.

Does Acute Caffeine Intake before Evening Training Sessions Impact Sleep Quality and Recovery-Stress State? Preliminary Results from a Study on Highly Trained Judo Athletes

No previous study has analyzed the impact of a low caffeine dose ingested before an evening training session on sleep and recovery-stress state. Nine highly trained judo athletes underwent a randomized, double-blind, placebo-controlled crossover experiment in which each athlete acted as their own control. Each athlete performed two identical trials after the ingestion of (i) a placebo and (ii) 3 mg of caffeine per kg of body mass, administered 60 min before an evening randori training session. Sleep was assessed using actigraphy and a Karolinska Sleep Diary (KSD), while the recovery-stress state was assessed using a short recovery and stress scale the morning following the trial. No significant differences were observed in any actigraphy sleep measures between conditions, or in the recovery-stress state (p > 0.05 for all). However, sleep quality assessed using the KSD was worse following caffeine ingestion compared with the placebo (3.0 ± 1.0 vs. 3.9 ± 0.6, respectively; p = 0.03, ES: 1.09). The ingestion of 3 mg/kg of caffeine before an evening training session has no impact on actigraphy-derived sleep measures or recovery-stress state. However, it leads to a substantial decrease in self-reported sleep quality.

PSV-A-3 Insulin in Sheep Under Different Patterns of Heat Stress

Abstract Livestock welfare and production are readily affected by thermal environment. However, the coordinate physiological shifts associated with heat stress differ substantially when animals have the opportunity to acclimate to thermal environments, or when night cooling occurs. Although some of these responses to thermal environment change have been characterized within some species, physiological signals in sheep associated with gradual versus drastic changes in ambient temperature have not been well studied. The objective of this study was to investigate changes in insulin concentration in sheep exposed to\ thermal environments representing different patterns of temperature change. We hypothesized that insulin would increase in response to rapidly elevated temperature. Six sheep (Suffolk, Dorset, or Suffolk x Dorset, 74.3 ± 13.3 kg) were assigned to 1 of 2 groups exposed to a cross-over experiment. Groups were assigned to 1 of 2 rooms, where they were housed for 20 d, prior to switching rooms. The thermal environment changed five times per period (every 4 d), starting at thermoneutral (20°C, 27°C, 35°C, 27°C, 20°C) in one room and hot (35°C, 27°C, 20°C, 27°C, 35°C) in the other room. Blood samples were collected via jugular venipuncture on day four of each sampling period. Plasma samples were analyzed for concentrations of insulin and glucagon by using a commercial enzyme-linked immunosorbent assay (Ovine Insulin ELISA kit, Eagle Biosciences Inc, #INO91-K01) per manufacturer’s instructions. Relationships were analyzed as a generalized linear model with insulin concentration as the response variable and temperature, room, period, and animal as fixed effects; 2- and 3-way interactions among temperature, room, and period were also evaluated. Insulin concentration ranged from 0.02 to 0.61 ng/mL, and was significantly influenced by animal (P = 0.044) and the interaction (P =0.004) between room and period. The interaction supports the idea that the pattern of heat loading, so more than absolute heat load modulates physiological adaptation to environment in the short-term

A cross‐over experiment for on‐farm evaluation of a novel pond aquaculture aeration device

On-farm experimentation is an essential part of aquacultural product development, but experimental designs that are commonly used for intensive commercial aquaculture are usually not suitable for earthen pond aquaculture, particularly in smallholder contexts. Guidance for on-farm testing of aeration technologies is similarly lacking. We therefore propose an experimental design (a cross-over experiment) that has not previously been applied to aeration in pond aquaculture, and we demonstrate its use as part of the field testing of a novel solar aeration device in Bangladesh. The cross-over experiment was less expensive than a large-scale randomized control trial, and we show that relying on randomization alone would have produced inaccurate results for this experiment. We analysed dissolved oxygen and fish growth rates using regression techniques, including multi-level regression and a generalized least-squares model with a lag-1 autocorrelation structure. We also describe the collaboration with a local farmer to build an experimental facility on his property, which was critical to the success of the experiment. The experiments showed that the device had a small impact on dissolved oxygen but was much less effective than commercially available products. On the other hand, the experimental design was effective and can be replicated to test other aeration technologies in on-farm conditions.

Adverse childhood experiences intensify retinal microvascular and inflammatory responses to semi-controlled acute traffic related air pollution exposure

Background: Potential synergy between childhood exposure to psychosocial stressors and traffic-related air pollution exposure, two factors that commonly overlap in socially disadvantaged groups, could increase the risk of cardiovascular disease and lead to greater health disparity than what is currently attributed to these factors independently. Aim: To test whether adverse childhood experiences (ACEs) potentiate the response of retinal microvasculature caliber and circulatory pro-inflammatory cytokines following a two-hour semi-controlled exposure to traffic related air pollution. Method: In a crossover experiment, 57 participants were exposed to near-traffic ambient air and filtered ambient air, in separate occasions for two hours each time. Central retinal arteriolar/venular equivalent (CRAE/CRVE), blood pressure, pulse, and circulating interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-α (TNF-α) were measured pre-exposure and, again, 1 hour and 24 hours post-exposure. ACEs were documented using the ACE questionnaire. Based on ACE scores, participants were grouped into high (ACE ≥ 4) and low (ACE ≤ 1) ACE groups. Microvascular and inflammatory response to the exposure were analyzed across groups. Results: ACE scores significantly predicted CRAE, IL-6, IL-8, and pulse reactivity. Left eye CRAE narrowing was greater in the high- vs. low-ACE group at 1-hour and 24-hours post-exposure. 24-hours post-exposure, IL-8 and pulse were significantly higher in the high- vs. low-ACE group. IL-6 was significantly lower in the high- vs. low-ACE group at 1-hour post-exposure. Conclusion: Our results support the hypothesis that ACEs may induce susceptibility to air pollution across the lifespan. These findings may thus help explain how health disparities develop and persist across the lifespan in persons who are most vulnerable to experiencing ACEs and poor air quality, leading to continued social disadvantage.

Investigation on visualization and heat transfer performance study of the mini-channel flow boiling

In recent years, mini-channel water flow boiling has been proven to have favorable cooling capability, especially for electronic component heat dissipation. Nevertheless, the fundamental principles related to flow boiling in mini-channel water lack clear comprehension, and the relevant experimental data on heat transfer performance and CHF visualization need to be supplemented. The behavior of vapor bubbles was explored in detail through visualization experiments to elucidate the mechanism of flow boiling and heat transfer in mini-channels. Meanwhile, the effects of mass flux, heat flux and tilt angle on the flow boiling of water and the CHF characteristics were revealed clearly though a series of crossover experiments. The results showed that in mini-channel water flow boiling, mass flux and heat flux will have effects on vapor bubble behavior, especially the merging of vapor bubbles, and then modify the heat transfer coefficient, and the mass flux in the optimal range exists. The tilt angle has less effect on the heat transfer coefficient, but affects the rate of vapor bubble growth. After local dryness the heat transfer mechanism transitions directly to film boiling instead of transition boiling, the boiling curve grows linearly with the wall superheat, and the CHF increases with increased mass flux. The research content of this paper helps to fill the gap in the experimental study of flow boiling in mini-channel and provides guidance for related practical applications.

DOES CARDIOMETABOLIC RESPONSE DIFFERS AT SELF-SELECTED AND PRESCRIBED INTENSITIES IN AEROBIC EXERCISES IN ADULTS?

Self-selection aerobic training loads seems to be helpful to the exercise enjoyment taking into account the practitioner decision on intensity level. It is recognized to increase pleasure and fun during exercise performance. Self-selection training load and personal relationships during exercise practice in small group help to maintain regular physical active behavior. PURPOSE: Compare the effect of different aerobic training protocols on heart rate, affective response, affectivity and intention to repeat the training session in both sex adults. PROCEDURES: 11 both sex adults, physically active (x = 56.3 + 10.2 years old and BMI = 29.2 + 2.4 kg/m2) participated in randomized crossover experiment design. Four aerobic training protocols on a treadmill were considered: 1) individual, self-selected intensity-AI; 2) individual with prescribed intensity (IP) (64-76% HRmax); 3) small group with self-selected intensity (SGI); 4) small group with prescribed intensity (SGP) (64-76% HRmax). Each protocol length was 30 minutes’ duration with 72 hours’ interval between sessions. Heart rate (HR), affective response (FS), entertainment (PACES) and intention to repeat the session (INTEN) were analyzed comparing all protocols. Single factor ANOVA (FC, FS and PACES) and paired t test (INTEN) with significance (p < .05) were performed to compare the results. RESULTS: HR analyzed has higher scores in AI, but without significant difference between the protocols (p > .05). FS shows less decline in AI (p < .05), higher PACES scores in AI (p > .05), as well as higher INTEN scores in AI (p < .05). We suggest that higher FS scores increase INTEN for repeating the exercise session.CONCLUSION: Aerobic training in self-selected intensity method was more enjoyable than other protocols (AI), what should be considered to increase affective, fun and intention to repeat the exercise session. Self-selected intensities can positively lead to adherence to the exercise program

Does intermittent theta burst stimulation improve working memory capacity? A randomized controlled cross-over experiment

ObjectiveIt has been hypothesized that intermittent theta burst stimulation (iTBS) can produce a memory-enhancing effect by inducing long-term potentiation (LTP)-like plasticity in the dorsolateral prefrontal cortex (DLPFC). However, the hemispheric difference by which iTBS modulates working memory in healthy adults has not been well investigated. The objective of the present study is to investigate the effects of iTBS on the left dorsolateral prefrontal cortex (LDLPFC) and right dorsolateral prefrontal cortex (RDLPFC) on working memory performance in healthy adults. MethodsIn this randomized cross-over experiment, 31 right-hand dominant healthy adults received a single-session of iTBS to their LDLPFC, RDLPFC and sham stimulation, in three different visits separated by a seven-day waiting period. Working memory capacity was assessed before and immediately after stimulation, by using 2-and 3-back tasks. ResultsAfter stimulation, significant time effects were found in overall accuracy when performing both 2- (p = 0.013) and 3-back tasks (p = 0.027), as well as the total reaction time during 3-back tasks (p = 0.021). Analysis of secondary outcomes showed an increase in the number of correction rejections in 2-back tasks (p = 0.009). However, all of the time-by-group interaction effects were not significant. ConclusionThis experiment did not find any additional memory-enhancing effects with a single-session of iTBS to either the RDLPFC or the LDLPFC in healthy adults beyond the practice effects.

Effects of online parietal transcranial electric stimulation on associative memory: a direct comparison between tDCS, theta tACS, and theta-oscillatory tDCS

Associative memory (AM) is the ability to remember and retrieve multiple items bound together. Previous studies aiming to modulate AM by various transcranial electric stimulation (tES) techniques were inconclusive, although overall suggestive that tES could be a tool for AM enhancement. However, evidence from a direct comparison between different tES techniques is lacking. Here, in a sham-controlled cross-over experiment, we comparatively assessed the effects of three types of tES—anodal tDCS, theta-band transcranial alternating current stimulation (tACS), and theta-oscillatory tDCS (otDCS), delivered over the left posterior parietal cortex, during a short-term digit-color AM task with cued-recall. The effects were tested in 40 healthy young participants while both oscillatory tES were delivered at a previously determined individual theta frequency (4–8 Hz). All three active stimulations facilitated the overall AM performance, and no differences could be detected between them on direct comparison. However, unlike tDCS, the effects of which appeared to stem mainly from the facilitation of low-memory demand trials, both theta-modulated tACS and otDCS primarily promoted AM in high memory demand trials. Comparable yet differential effects of tDCS, theta tACS, and otDCS could be attributed to differences in their presumed modes of action.

Highly Regio- and Stereoselective Intramolecular Rearrangement of Glycidol Acetal to Alkoxy Cyclic Acetals.

A new class of highly regio- and stereoselective intramolecular rearrangements of glycidol acetals to produce alkoxylated 1,3-dioxolane/1,3-dioxane is demonstrated. Selective Lewis acid activation of acetal generates an oxocarbenium ion that initiates the epoxide ring-opening event, giving the bicyclic [3,1,0]epoxonium ion intermediate that undergoes exo/endo-selective opening by a tethered alkoxide. Mechanistic insights into preferential acetal activation over the epoxide were obtained by crossover experiments. The method was applied in the total synthesis of parvistone B and its 8-ethoxy analogue.

A deep learning approach for electromechanical impedance based concrete structural damage quantification using two-dimensional convolutional neural network

Deep learning approach using convolutional neural networks (CNNs) has ushered in numerous breakthroughs in image-based recognition field, but the electromechanical impedance/admittance (EMI/EMA)-based structural damage identification by CNN remains being refined. This paper proposed a deep learning approach for the raw EMA-based rapid damage quantification on concrete structure utilizing two-dimensional (2D) CNNs. In the approach, the EMA signatures are first split into multiple sub-range responses, among which corresponding to the maximum indices namely root mean square deviations (RMSDs) are selected to construct the input of CNNs for training, and then damage severity degree could be rapidly predicted. The proposed approach is verified through crossover experiments of detecting multiple mass loss damages on a cubic concrete structure. Effect of input size on the performance of the approach is also evaluated by developing different CNN models. Experimental results confirm that the proposed approach is of high accuracy and efficiency even to tiny damages, thus paving a promising way to the real-life monitoring for concrete structures.