The effects of Lysergic Acid Diethylamide (LSD) on the Positive Valence Systems: A Research Domain Criteria (RDoC)-Informed Systematic Review

BACKGROUND AND OBJECTIVES

The renewed interest in psychedelic research provides growing evidence of potentially unique effects on various aspects of reward processing systems. Using the Research Domain Criteria (RDoC) framework, as proposed by the National Institute of Mental Health, we aim to synthesize the existing literature concerning the impact of lysergic acid diethylamide (LSD) on the RDoC's Positive Valence Systems (PVS) domain, and to identify potential avenues for further research.

METHODS

Two LSD-related terms (lysergic acid diethylamide and LSD) and 13 PVS-related terms (reward, happiness, bliss, motivation, reinforcement learning, operant, conditioning, satisfaction, decision making, habit, valence, affect, mood) were used to search electronic databases such as PubMed, Scopus, PsychINFO, and Web of Science for relevant articles. A manual search of the reference list resulted in nine additional articles. After screening, articles and data were evaluated and included based on their relevance to the objective of investigating the effects of LSD on the PVS. Articles and data were excluded if they did not provide information about the PVS, were observational in nature, lacked comparators or reference groups, or were duplicates. A risk of bias assessment was performed using the National Toxicology Program's Office of Health Assessment and Translation (NTP OHAT) risk of bias (RoB) tool. Data from the included articles were collected and structured based on the RDoC bio-behavioral matrix, specifically focusing on the PVS domain and its three constituent constructs: reward responsiveness, reward learning, and reward valuation.

RESULTS

We reviewed 28 clinical studies with 477 participants. Lysergic acid diethylamide, assessed at self-report (23 studies), molecular (5 studies), circuit (4 studies), and paradigm (3 studies) levels, exhibited dose-dependent mood improvement (20 short-term and 3 long-term studies). The subjective and neural effects of LSD were linked to the 5-HT2A receptor (molecular). Animal studies (14 studies) suggested LSD could mildly reinforce conditioned place preference without aversion and reduce responsiveness to other rewards. Findings on reward learning were inconsistent but hinted at potential associative learning enhancements. Reward valuation measures indicated potential reductions in effort expenditure for other reinforcers.

CONCLUSION

Our findings are consistent with our previous work, which indicated classical psychedelics, primarily serotonin 2A receptor agonists, enhanced reward responsiveness in healthy individuals and patient populations. Lysergic acid diethylamide exhibits a unique profile in the reward learning and valuation constructs. Using the RDoC-based framework, we identified areas for future research, enhancing our understanding of the impact of LSD on reward processing. However, applying RDoC to psychedelic research faces limitations due to diverse study designs that were not initially RDoC-oriented. Limitations include subjective outcome measure selection aligned with RDoC constructs and potential bias in synthesizing varied studies. Additionally, some human studies were open-label, introducing potential bias compared to randomized, blinded studies.

Visual impairment following aluminum phosphide poisoning: A rare case

Key Clinical Message

Aluminum phosphide poisoning may cause rare visual impairment. In a case, a 31-year-old female, visual loss was linked to shock-induced hypoperfusion, causing oxygen lack and cerebral atrophy, emphasizing the need for identifying atypical symptoms.

Abstract

This case report describes the multidisciplinary evaluation of a 31-year-old female patient who suffered from visual impairment as a result of aluminum phosphide (AlP) poisoning. Phosphine, which is formed in the body when AlP reacts with water, cannot cross the blood-brain barrier; therefore, visual impairment seems unlikely to be the direct result of phosphine. To our knowledge, it is the first documented report of such impairment due to AlP.

Demographic and Clinical Characteristics of 907 Cases with Naltrexone Intoxication; a 14-Year Cross-Sectional Study

INTRODUCTION

Opioids have been the leading cause of death from poisoning in Iran for several years. This study aimed to evaluate the clinical and para-clinical presentations of naltrexone intoxication, its toxic dose, and its epidemiological properties.

METHODS

This retrospective cross-sectional study was conducted on medical records of patients presenting to Toxicology Department of Loghman Hakim Hospital, Tehran, Iran, following naltrexone intoxication, from 2002 to 2016. Patients' demographic and laboratory data, clinical signs, supposed ingested dose, and intent of naltrexone consumption were collected, analyzed, and then interpreted.

RESULTS

907 patients with the mean age of 36.6 ±11.7 years were evaluated (94.3% male). The mean amount of naltrexone consumed by the intoxicated patients reported in the medical records was 105.8 ± 267.8 mg. One hundred thirty patients (14.3%) used naltrexone to treat substance use disorder. Two hundred eighty-seven poisoned patients (31.6%) were current opium users who intentionally or unintentionally used naltrexone concomitantly. The most common symptoms observed in these patients were agitation (41.8%), vomiting (16.4%), and nausea (14.8%). Among patients with naltrexone poisoning, 25 patients were intubated (2.8%), and three passed away. Aspartate aminotransferase (AST) levels were significantly higher in patients intoxicated with naltrexone who needed intubation (p = 0.02).

CONCLUSION

The probability of intubation of cases with naltrexone intoxication was associated with AST elevation. It seems that, the number of intensive care unit (ICU) admissions and mortality rates are not high among these patients.

Delirium treatment in intoxicated patients in ICU: A randomized, double-blind clinical trial

Objective: Delirium is one of the most common complications in patients admitted to intensive care units (ICUs). Delirium is a definite cause for more extended hospital stays, higher mortality rates, and possibly persistent cognitive decline in the future. Antipsychotics have been frequently evaluated as first drugs of choice, but the most appropriate, evidence-based treatment is yet to be discovered. This study aims to compare the efficacy of haloperidol and olanzapine in patients admitted to our toxicology ICU. Methods: This double-blind, randomized controlled clinical trial was undertaken on 35 ICU admitted patients with delirium in Loghman Hakim hospital in Tehran, Iran. The diagnosis was based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) criteria for delirium, and clinical toxicologists included the patients according to the study’s inclusion and exclusion criteria. Patients received either haloperidol or olanzapine based on computerized randomization. The severity of delirium was measured with the Memorial Delirium Assessment Scale (MDAS) scoring on days 0 and 3 of ICU-admission. Results: The total sample size was 35 in which 16 patients received haloperidol, and 19 patients received olanzapine. The doses of haloperidol and olanzapine were 3 mg three times a day and 5 mg three times a day, respectively. There was no significant difference in baseline characteristics and the scores of MDAS between groups. Conclusion: Olanzapine and haloperidol have the same efficacy in the management of delirium in toxicology ICU-admitted patients. They can be interchangeably used for delirium treatment in these patients.

Clinical Manifestations and Outcomes of Colchicine Poisoning Cases; a Cross Sectional Study

INTRODUCTION

Colchicine is a medication with narrow therapeutic index, leading to both accidental and suicidal poisonings incidents. This study aimed to investigate the clinical and laboratory manifestations, as well as outcomes of colchicine poisoning patients referred to emergency department.

METHODS

In this retrospective cross sectional study, demographics, clinical features, laboratory parameters, and outcomes of colchicine poisoned patients who were admitted to an academic referral center, Tehran, Iran, during 7 years were extracted from the patients' profiles and analyzed.

RESULTS

21 patients with the mean age of 25.48 ± 12.65 years were studied (61.9% female; 85.7% suicidal). The mean ingested colchicine dose was 30.25 ± 21.09 mg. The most common symptoms were nausea and vomiting observed in 19 (90.5%) cases, followed by abdominal pain in 10 (47.6%) and diarrhea in 9 (42.8%) cases. 3 (14.3%) had died, the cause being disseminated intravascular coagulation (DIC) in two cases and severe metabolic acidosis in one. Prevalence of abdominal tenderness (p = 0.001) and abdominal pain (p = 0.049) was significantly different between survived and non-survived patients. There were significant correlations between systolic blood pressure (p = 0.010), diastolic blood pressure (p = 0.002), serum glucose (p = 0.031), calcium (p = 0.017), white blood cell (WBC) count (p = 0.043), aspartate aminotransferase (AST) (p = 0.001), alkaline phosphatase (ALP) (p = 0.012), prothrombin time (PT) (p = 0.006), partial thromboplastin time (PTT) (p = 0.014), PaCO₂ (p = 0.011), DIC (p < 0.001), and need for mechanical ventilation (p = 0.024) with survival.

CONCLUSIONS

Based on the findings of the present study, the mortality rate of colchicine poisoning was 14.3% and there was significant correlation between lower blood pressure, lower serum glucose and calcium levels, lower PaCO₂, higher WBC count, higher AST and ALP levels, higher PT and PTT, need for mechanical ventilation, presence of DIC, and also abdominal pain and tenderness with survival.

Validation of Iranian Smell Identification Test for screening of mild cognitive impairment and Alzheimer's disease

Background: According to the World Alzheimer Report 2019, an estimated 50 million people worldwide are living with dementia. The smell test is a method for early detection of Alzheimer's disease (AD) as an inexpensive, simple, and noninvasive screening tool. This study aimed to evaluate the accuracy of the Iran Smell Identification Test (Iran-SIT) in discriminating patients with AD, with mild cognitive impairment (MCI), and the healthy subjects.Methods: In this study, 42 patients with AD, 33 with MCI, and 32 healthy controls were recruited from the referral Memory Clinic of Tehran University of Medical Sciences. The olfactory function was examined with six odors through Iran-SIT.Results: We found a significant difference among the olfactory function in subjects with normal cognitive status, that of those with MCI and those with AD (p < 0.001). The cutoff point for the diagnosis of AD was (sensitivity and specificity were, respectively, 85.7 and 90.8%), and (Sensitivity and specificity were, respectively, 93.9 and 100%) for MCI.Conclusion: These results suggest that Iran-SIT is a valid biomarker and practical screening tool, with simple, inexpensive, and readily available for use in combination with neuropsychological tools and neuroimaging for early detection of AD.

GaP/GaNP Heterojunctions for Efficient Solar-Driven Water Oxidation

The growth and characterization of an n-GaP/i-GaNP/p⁺ -GaP thin film heterojunction synthesized using a gas-source molecular beam epitaxy (MBE) method, and its application for efficient solar-driven water oxidation is reported. The TiO₂ /Ni passivated n-GaP/i-GaNP/p⁺ -GaP thin film heterojunction provides much higher photoanodic performance in 1 m KOH solution than the TiO₂ /Ni-coated n-GaP substrate, leading to much lower onset potential and much higher photocurrent. There is a significant photoanodic potential shift of 764 mV at a photocurrent of 0.34 mA cm^-2 , leading to an onset potential of ≈0.4 V versus reversible hydrogen electrode (RHE) at 0.34 mA cm^-2 for the heterojunction. The photocurrent at the water oxidation potential (1.23 V vs RHE) is 1.46 and 7.26 mA cm^-2 for the coated n-GaP and n-GaP/i-GaNP/p⁺ -GaP photoanodes, respectively. The passivated heterojunction offers a maximum applied bias photon-to-current efficiency (ABPE) of 1.9% while the ABPE of the coated n-GaP sample is almost zero. Furthermore, the coated n-GaP/i-GaNP/p⁺ -GaP heterojunction photoanode provides a broad absorption spectrum up to ≈620 nm with incident photon-to-current efficiencies (IPCEs) of over 40% from ≈400 to ≈560 nm. The high low-bias performance and broad absorption of the wide-bandgap GaP/GaNP heterojunctions render them as a promising photoanode material for tandem photoelectrochemical (PEC) cells to carry out overall solar water splitting.

High-performance flexible hydrogen sensor made of WS₂ nanosheet-Pd nanoparticle composite film

We report a flexible hydrogen sensor, composed of WS2 nanosheet-Pd nanoparticle composite film, fabricated on a flexible polyimide substrate. The sensor offers the advantages of light-weight, mechanical durability, room temperature operation, and high sensitivity. The WS2-Pd composite film exhibits sensitivity (R 1/R 2, the ratio of the initial resistance to final resistance of the sensor) of 7.8 to 50,000 ppm hydrogen. Moreover, the WS2-Pd composite film distinctly outperforms the graphene-Pd composite, whose sensitivity is only 1.14. Furthermore, the ease of fabrication holds great potential for scalable and low-cost manufacturing of hydrogen sensors.

Graphene oxide as a p-dopant and an anti-reflection coating layer, in graphene/silicon solar cells

It is shown that coating graphene-silicon (Gr/Si) Schottky junction based solar cells with graphene oxide (GO) improves the power conversion efficiency (PCE) of the cells, while demonstrating unprecedented device stability. The PCE has been shown to be increased to 10.6% (at incident radiation of 100 mW cm(-2)) for the Gr/Si solar cell with an optimal GO coating thickness compared to 3.6% for a bare/uncoated Gr/Si solar cell. The p-doping of graphene by the GO, which also serves as an antireflection coating (ARC) has been shown to be a main contributing factor to the enhanced PCE. A simple spin coating process has been used to apply GO with thickness commensurate with an anti-refection coating (ARC) and indicates the suitability of the developed methodology for large-scale solar cell assembly.

Enhanced Power Conversion Efficiency of Graphene/Silicon Heterojunction Solar Cells Through NiO Induced Doping

We report a doping strategy, where nickel oxide (NiO) nanoparticle film coating is employed for graphene/Si heterojunction solar cells to improve the power conversion efficiency (PCE). NiO doping has been shown to improve the short circuit current (J(SC)) by 12%, open circuit voltage (V(OC)) by 25% and fill factor (FF) by 145% of the cells, in turn increasing the PCE from 1.37% to 4.91%. Furthermore, NiO doped graphene/Si solar cells don't show any significant performance degradation over 10 days revealing that NiO doping can be a promising approach for practical applications of graphene in solar cells.

Solution-Processed CoFe2O4 Nanoparticles on 3D Carbon Fiber Papers for Durable Oxygen Evolution Reaction

We report CoFe2O4 nanoparticles (NPs) synthesized using a facile hydrothermal growth and their attachment on 3D carbon fiber papers (CFPs) for efficient and durable oxygen evolution reaction (OER). The CFPs covered with CoFe2O4 NPs show orders of magnitude higher OER performance than bare CFP due to high activity of CoFe2O4 NPs, leading to a small overpotential of 378 mV to get a current density of 10 mA/cm(2). Significantly, the CoFe2O4 NPs-on-CFP electrodes exhibit remarkably long stability evaluated by continuous cycling (over 15 h) and operation with a high current density at a fixed potential (over 40 h) without any morphological change and with preservation of all materials within the electrode. Furthermore, the CoFe2O4 NPs-on-CFP electrodes also exhibit hydrogen evolution reaction (HER) performance, which is considerably higher than that of bare CFP, acting as a bifunctional electrocatalyst. The achieved results show promising potential for efficient, cost-effective, and durable hydrogen generation at large scales using earth-abundant materials and cheap fabrication processes.

High-Performance a-Si/c-Si Heterojunction Photoelectrodes for Photoelectrochemical Oxygen and Hydrogen Evolution

Amorphous Si (a-Si)/crystalline Si (c-Si) heterojunction (SiHJ) can serve as highly efficient and robust photoelectrodes for solar fuel generation. Low carrier recombination in the photoelectrodes leads to high photocurrents and photovoltages. The SiHJ was designed and fabricated into both photoanode and photocathode with high oxygen and hydrogen evolution efficiency, respectively, by simply coating of a thin layer of catalytic materials. The SiHJ photoanode with sol-gel NiOx as the catalyst shows a current density of 21.48 mA/cm(2) at the equilibrium water oxidation potential. The SiHJ photocathode with 2 nm sputter-coated Pt catalyst displays excellent hydrogen evolution performance with an onset potential of 0.640 V and a solar to hydrogen conversion efficiency of 13.26%, which is the highest ever reported for Si-based photocathodes.

MoS2 Nanosheet-Pd Nanoparticle Composite for Highly Sensitive Room Temperature Detection of Hydrogen

Highly sensitive hydrogen detection at room temperature can be realized by employing solution-processed MoS2 nanosheet-Pd nanoparticle composite. A MoS2-Pd composite exhibits greater sensing performance than its graphene counterpart, indicating that solvent exfoliated MoS2 holds great promise for inexpensive and scalable fabrication of highly sensitive chemical sensors.

NiO(x)-Fe2O3-coated p-Si photocathodes for enhanced solar water splitting in neutral pH water

We report successful growth of a uniform and scalable nanocomposite film of Fe2O3 nanorods (NRs) and NiOx nanoparticles (NPs), their properties and application for enhanced solar water reduction in neutral pH water on the surface of p-Si photocathodes.

Atomic scale analysis of the enhanced electro- and photo-catalytic activity in high-index faceted porous NiO nanowires

Catalysts play a significant role in clean renewable hydrogen fuel generation through water splitting reaction as the surface of most semiconductors proper for water splitting has poor performance for hydrogen gas evolution. The catalytic performance strongly depends on the atomic arrangement at the surface, which necessitates the correlation of the surface structure to the catalytic activity in well-controlled catalyst surfaces. Herein, we report a novel catalytic performance of simple-synthesized porous NiO nanowires (NWs) as catalyst/co-catalyst for the hydrogen evolution reaction (HER). The correlation of catalytic activity and atomic/surface structure is investigated by detailed high resolution transmission electron microscopy (HRTEM) exhibiting a strong dependence of NiO NW photo- and electrocatalytic HER performance on the density of exposed high-index-facet (HIF) atoms, which corroborates with theoretical calculations. Significantly, the optimized porous NiO NWs offer long-term electrocatalytic stability of over one day and 45 times higher photocatalytic hydrogen production compared to commercial NiO nanoparticles. Our results open new perspectives in the search for the development of structurally stable and chemically active semiconductor-based catalysts for cost-effective and efficient hydrogen fuel production at large scale.

Comparison of two different doses of dexmedetomidine in attenuating cardiovascular responses during laryngoscopy and endotracheal intubation: A double blind, randomized, clinical trial study

Introduction. Secure airway for proper ventilation during anesthesia is one important component of a successful surgery. Endotracheal intubation is one of the most important methods in this context. Intubation method and used medication are considerably important in attenuating complications. This research aimed to investigate the impact of two different doses of dexmedetomidine in mitigating cardiovascular responses to endotracheal intubation in candidate cases supporting voluntary operation. Methods. The current research contained 90 cases in the range of 18 and 50 old, with ASA I,II supporting voluntary operation, who were randomly classified into three teams, each group consisting of 30 cases. The first set (A) got 0.5 μg/ kg dexmedetomidine, the second set (B) got 1 μg/ kg dexmedetomidine and the third set (C) got an equal volume of saline as placebo, 600 seconds earlier the initiation of anesthesia. Hemodynamic parameters were recorded at baseline (T0), then after the injection and the earlier initiation of anesthesia (T1), after the induction of anesthesia and before the endotracheal intubation (T2), promptly after tracheal intubation, 180, and 300 after endotracheal intubation (T4, T5). Data was analyzed and p < 0.05 was supposed notable. Findings. In this research, 3 teams were similar regarding weight, age, height, sex and duration of laryngoscopy. The diastolic mean arterial pressure, heart rate, and systolic arterial pressure were significantly lower in dexmedetomidine teams (A,B) at all times after the endotracheal intubation compared to group C. There were no significant differences in hemodynamic factors among group A, B. Conclusion. Dexmedetomidine effectively and significantly attenuates cardiovascular and hemodynamic responses during endotracheal intubation. In addition, different doses of dexmedetomidine did not cause any significant distinct result in mitigating cardiovascular responses.

Solution-grown 3D Cu2O networks for efficient solar water splitting

We report a facile and large-scale solution fabrication of cuprous oxide (Cu2O) nanowires/nanorods and 3D porous Cu2O networks and their application as photocathodes for efficient solar water splitting. The growth mechanism and structural characterization of 3D porous Cu2O networks are studied in detail. The photocathodic performance of Cu2O electrodes prepared under different growth conditions is investigated in a pH-neutral medium. The porous Cu2O network photocathodes exhibit large photocurrent, high spectral photoresponse, and incident photon-to-current efficiency compared with Cu2O nanowire/nanorod photoelectrodes. The photoelectrochemical stability of the 3D Cu2O network is significantly improved by applying multi-layer metal oxide protection.

ZnO/CuO heterojunction branched nanowires for photoelectrochemical hydrogen generation

We report a facile and large-scale fabrication of three-dimensional (3D) ZnO/CuO heterojunction branched nanowires (b-NWs) and their application as photocathodes for photoelectrochemical (PEC) solar hydrogen production in a neutral medium. Using simple, cost-effective thermal oxidation and hydrothermal growth methods, ZnO/CuO b-NWs are grown on copper film or mesh substrates with various ZnO and CuO NWs sizes and densities. The ZnO/CuO b-NWs are characterized in detail using high-resolution scanning and transmission electron microscopies exhibiting single-crystalline defect-free b-NWs with smooth and clean surfaces. The correlation between electrode currents and different NWs sizes and densities are studied in which b-NWs with longer and denser CuO NW cores show higher photocathodic current due to enhanced reaction surface area. The ZnO/CuO b-NW photoelectrodes exhibit broadband photoresponse from UV to near IR region, and higher photocathodic current than the ZnO-coated CuO (core/shell) NWs due to improved surface area and enhanced gas evolution. Significant improvement in the photocathodic current is observed when ZnO/CuO b-NWs are grown on copper mesh compared to copper film. The achieved results offer very useful guidelines in designing b-NWs mesh photoelectrodes for high-efficiency, low-cost, and flexible PEC cells using cheap, earth-abundant materials for clean solar hydrogen generation at large scales.

Didactic Lecture Versus Interactive Workshop for Continuing Pharmacy Education on Reproductive Health

Pharmacists are routinely providing reproductive health counseling in community pharmacies, but studies have revealed significant deficits in their competencies. Therefore, continuing pharmacy education (CPE) could be utilized as a valuable modality to upgrade pharmacists’ capabilities. A randomized controlled trial was designed to compare the efficacy of CPE meetings (lecture based vs. workshop based) on contraception and male sexual dysfunctions. Sixty pharmacists were recruited for each CPE meeting. Small group training using simulated patients was employed in the workshop-based CPE. Study outcomes were declarative/procedural knowledge, attitudes, and satisfaction of the participants. Data were collected pre-CPE, post-CPE, and 2 months afterward and were analyzed using repeated measure analysis of variance and Mann–Whitney U test. Results showed that lecture-based CPE was more successful in improving pharmacists’ knowledge post-CPE ( p < .001). In contrast, a significant decrease was observed in the lecture-based group at follow-up ( p = .002), whereas the workshop-based group maintained their knowledge over time ( p = 1.00). Knowledge scores of both groups were significantly higher at follow-up in comparison with pre-CPE ( p < .01). No significant differences were observed regarding satisfaction and attitudes scores between groups. In conclusion, an interactive workshop might not be superior to lecture-based training for improving pharmacists’ knowledge and attitudes in a 1-day CPE meeting.

3D Branched nanowire photoelectrochemical electrodes for efficient solar water splitting

We report the systematic study of 3D ZnO/Si branched nanowire (b-NW) photoelectrodes and their application in solar water splitting. We focus our study on the correlation between the electrode design and structures (including Si NW doping, dimension of the trunk Si and branch ZnO NWs, and b-NW pitch size) and their photoelectrochemical (PEC) performances (efficiency and stability) under neutral conditions. Specifically, we show that for b-NW electrodes with lightly doped p-Si NW core, larger ZnO NW branches and longer Si NW cores give a higher photocathodic current, while for b-NWs with heavily doped p-Si NW trunks smaller ZnO NWs and shorter Si NWs provide a higher photoanodic current. Interestingly, the photocurrent turn-on potential decreases with longer p-Si NW trunks and larger ZnO NW branches resulting in a significant photocathodic turn-on potential shift of ~600 mV for the optimized ZnO/p-Si b-NWs compared to that of the bare p-Si NWs. A photocathode energy conversion efficiency of greater than 2% at -1 V versus Pt counter electrode and in neutral solution is achieved for the optimized ZnO/p-Si b-NW electrodes. The PEC performances or incident photon-to-current efficiency are further improved using Si NW cores with smaller pitch size. The photoelectrode stability is dramatically improved by coating a thin TiO2 protection layer using atomic-layer deposition method. These results provide very useful guidelines in designing photoelectrodes for selective solar water oxidation/reduction and overall spontaneous solar fuel generation using low cost earth-abundant materials for practical clean solar fuel production.

Tactile feedback display with spatial and temporal resolutions

We report the electronic recording of the touch contact and pressure using an active matrix pressure sensor array made of transparent zinc oxide thin-film transistors and tactile feedback display using an array of diaphragm actuators made of an interpenetrating polymer elastomer network. Digital replay, editing and manipulation of the recorded touch events were demonstrated with both spatial and temporal resolutions. Analog reproduction of the force is also shown possible using the polymer actuators, despite of the high driving voltage. The ability to record, store, edit, and replay touch information adds an additional dimension to digital technologies and extends the capabilities of modern information exchange with the potential to revolutionize physical learning, social networking, e-commerce, robotics, gaming, medical and military applications.

Tailoring n-ZnO/p-Si branched nanowire heterostructures for selective photoelectrochemical water oxidation or reduction

We report the fabrication of three-dimensional (3D) branched nanowire (NW) heterostructures, consisting of periodically ordered vertical Si NW trunks and ZnO NW branches, and their application for solar water splitting. The branched NW photoelectrodes show orders of magnitudes higher photocurrent compared to the bare Si NW electrodes. More interestingly, selective photoelectrochemical cathodic or anodic behavior resulting in either solar water oxidation or reduction was achieved by tuning the doping concentration of the p-type Si NW core. Specifically, n-ZnO/p-Si branched NW array electrodes with lightly doped core show broadband absorption from UV to near IR region and photocathodic water reduction, while n-ZnO/p(+)-Si branched NW arrays show photoanodic water oxidation with photoresponse only to UV light. The photoelectrochemical stability for over 24 h under constant light illumination and fixed biasing potential was achieved by coating the branched NW array with thin layers of TiO2 and Pt. These studies not only reveal the promise of 3D branched NW photoelectrodes for high efficiency solar energy harvesting and conversion to clean chemical fuels, but also developing understanding enabling rational design of high efficiency robust photocathodes and photoanodes from low-cost and earth-abundant materials allowing practical applications in clean renewable energy.

3D branched nanowire heterojunction photoelectrodes for high-efficiency solar water splitting and H2 generation

We report the fabrication of a three dimensional branched ZnO/Si heterojunction nanowire array by a two-step, wafer-scale, low-cost, solution etching/growth method and its use as photoelectrode in a photoelectrochemical cell for high efficiency solar powered water splitting. Specifically, we demonstrate that the branched nanowire heterojunction photoelectrode offers improved light absorption, increased photocurrent generation due to the effective charge separation in Si nanowire backbones and ZnO nanowire branching, and enhanced gas evolution kinetics because of the dramatically increased surface area and decreased radius of curvature. The branching nanowire heterostructures offer direct functional integration of different materials for high efficiency water photoelectrolysis and scalable photoelectrodes for clean hydrogen fuel generation.

Design and optimization of waveguide sensitivity in slot microring sensors

The waveguide sensitivity of silicon slot microring sensors and single- and double-slot microrings is analyzed using a combination of the effective index and the Airy-functions-based mode matching methods. The sensing properties of these two cases are investigated under a variety of geometries. The trends of the waveguide sensitivity on each geometrical parameter are obtained. In addition, the influence of asymmetry on the waveguide sensitivity is also investigated. Calculation also illustrates that double-slot microrings offer wider fabrication tolerance than single-slot ones. These results provide a guideline and insights for designing microring geometry to satisfy the desired sensing requirements and performance.