The monolayer arsenic in the puckered honeycomb structure was recently predicted to be a stable two-dimensional layered semiconductor and therefore named arsenene. Unfortunately, it has an indirect band gap, which lim...The monolayer arsenic in the puckered honeycomb structure was recently predicted to be a stable two-dimensional layered semiconductor and therefore named arsenene. Unfortunately, it has an indirect band gap, which limits its practical application. Using first-principles calculations, we show that the band gaps of few-layer arsenic have an indirect-direct transition as the number of arsenic layers(n) increases from n=1 to n=2. As n increases from n=2 to infinity, the stacking of the puckered honeycomb arsenic layers forms the orthorhombic arsenic crystal ??-As, arsenolamprite), which has a similar structure to the black phosphorus and also has a direct band gap. This indirect-direct transition stems from the distinct quantum-confinement effect on the indirect and direct band-edge states with different wavefunction distribution. The strain effect on these electronic states is also studied, showing that the in-plane strains can induce very different shift of the indirect and direct band edges, and thus inducing an indirect-direct band gap transition too. The band gap dependence on strain is non-monotonic, with both positive and negative deformation potentials. Although the gap of arsenene opens between As p-p bands, the spin-orbit interaction decreases the gap by only 0.02 e V, which is much smaller than the decrease in Ga As with an s-p band gap. The calculated band gaps of arsenene and ?-As using the hybrid functional are 1.4 and 0.4 e V respectively, which are comparable to those of phosphorene and black phosphorus.展开更多
AIM: To compare adherence, response, and remission with light treatment in African-American and Caucasian patients with Seasonal Affective Disorder.METHODS: Seventy-eight study participants, agerange 18-64(51 African-...AIM: To compare adherence, response, and remission with light treatment in African-American and Caucasian patients with Seasonal Affective Disorder.METHODS: Seventy-eight study participants, agerange 18-64(51 African-Americans and 27 Caucasians)recruited from the Greater Baltimore Metropolitan area, with diagnoses of recurrent mood disorder with seasonal pattern, and confirmed by a Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders-Ⅳ, were enrolled in an open label study of daily bright light treatment. The trial lasted6 wk with flexible dosing of light starting with 10000 lux bright light for 60 min daily in the morning. At the end of six weeks there were 65 completers. Three patients had Bipolar Ⅱ disorder and the remainder had Major depressive disorder. Outcome measures were remission(score ≤ 8) and response(50% reduction)in symptoms on the Structured Interview Guide for the Hamilton Rating Scale for Depression(SIGH-SAD)as well as symptomatic improvement on SIGH-SAD and Beck Depression Inventory-Ⅱ. Adherence was measured using participant daily log. Participant groups were compared using t-tests, chi square, linear and logistic regressions. RESULTS: The study did not find any significant group difference between African-Americans and their Caucasian counterparts in adherence with light treatment as well as in symptomatic improvement.While symptomatic improvement and rate of treatment response were not different between the two groups,African-Americans, after adjustment for age, gender and adherence, achieved a significantly lower remission rate(African-Americans 46.3%; Caucasians 75%; P =0.02).CONCLUSION: This is the first study of light treatment in African-Americans, continuing our previous work reporting a similar frequency but a lower awareness of SAD and its treatment in African-Americans. Similar rates of adherence, symptomatic improvement and treatment response suggest that light treatment is a feasible, acceptable, and beneficial treatment for SAD in African-American patients. These results should lead to intensifying education initiatives to increase awareness of SAD and its treatment in African-American communities to increased SAD treatment engagement.In African-American vs Caucasian SAD patients a remission gap was identified, as reported before with antidepressant medications for non-seasonal depression, demanding sustained efforts to investigate and then address its causes.展开更多
The optical absorption properties of femtosecond-laser-made ＂black silicon＂ as a function of the annealing conditions were investigated. We found that the annealing process changes the surface morphology and absorpt...The optical absorption properties of femtosecond-laser-made ＂black silicon＂ as a function of the annealing conditions were investigated. We found that the annealing process changes the surface morphology and absorption spectroscopy of the ＂black silicon＂ samples, and obtained a maximum sub-band-gap absorptance value of approximately 30% by annealing at 1000 ~C for 30 min. The thermal relaxation and atomic structural transformation mechanisms are used to describe the lat- tice recovery and the increase and decrease of the substitutional dopant atom concentration in the microstructured surface during the annealing. Our results confirm that： i） owing to the ther- mal relaxation, the lattice defects decrease with the increase of the annealing temperature; ii） the quasi-substitutional and interstitial configurations of the doped atoms transform into substitutional arrangements when the annealing temperature increases; iii） the quasi-substitutional and intersti- tial configurations with higher energies of the doped atoms transform into interstitial configurations with the lowest energy after high-temperature annealing for a long period of time, causing the de- activation or reactivation of the sub-band-gap absorptance by diffusion. The results demonstrate that the annealing can improve the properties of ＂black silicon＂, including defects repairing, carrier lifetime lengthening, and retention of a high absorptive performance.展开更多
基金supported by the Special Funds for Major State Basic Research of China(Grant Nos.2012CB921401,2014CB921104)National Natural Science Foundation of China(Grant Nos.61106087,91233121 and 61125403)+1 种基金Shanghai Rising-Star Program(Grant No.14QA1401500)the Program for Changjiang Scholars and Innovative Research Team in University,and the computer center of East China Normal University
文摘The monolayer arsenic in the puckered honeycomb structure was recently predicted to be a stable two-dimensional layered semiconductor and therefore named arsenene. Unfortunately, it has an indirect band gap, which limits its practical application. Using first-principles calculations, we show that the band gaps of few-layer arsenic have an indirect-direct transition as the number of arsenic layers(n) increases from n=1 to n=2. As n increases from n=2 to infinity, the stacking of the puckered honeycomb arsenic layers forms the orthorhombic arsenic crystal ??-As, arsenolamprite), which has a similar structure to the black phosphorus and also has a direct band gap. This indirect-direct transition stems from the distinct quantum-confinement effect on the indirect and direct band-edge states with different wavefunction distribution. The strain effect on these electronic states is also studied, showing that the in-plane strains can induce very different shift of the indirect and direct band edges, and thus inducing an indirect-direct band gap transition too. The band gap dependence on strain is non-monotonic, with both positive and negative deformation potentials. Although the gap of arsenene opens between As p-p bands, the spin-orbit interaction decreases the gap by only 0.02 e V, which is much smaller than the decrease in Ga As with an s-p band gap. The calculated band gaps of arsenene and ?-As using the hybrid functional are 1.4 and 0.4 e V respectively, which are comparable to those of phosphorene and black phosphorus.
基金Supported by The National Institute of Mental Health of the National Institutes of Health under award No.1R34MH073797-01A2(PI Postolache TT)in part by the National Institutes of Health award No.K12RR023250-01(PI Reeves GM)by the National Center for Research Resources of the National Institutes of Health award No.M01 RR 16500(General Clinical Research Program)
文摘AIM: To compare adherence, response, and remission with light treatment in African-American and Caucasian patients with Seasonal Affective Disorder.METHODS: Seventy-eight study participants, agerange 18-64(51 African-Americans and 27 Caucasians)recruited from the Greater Baltimore Metropolitan area, with diagnoses of recurrent mood disorder with seasonal pattern, and confirmed by a Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders-Ⅳ, were enrolled in an open label study of daily bright light treatment. The trial lasted6 wk with flexible dosing of light starting with 10000 lux bright light for 60 min daily in the morning. At the end of six weeks there were 65 completers. Three patients had Bipolar Ⅱ disorder and the remainder had Major depressive disorder. Outcome measures were remission(score ≤ 8) and response(50% reduction)in symptoms on the Structured Interview Guide for the Hamilton Rating Scale for Depression(SIGH-SAD)as well as symptomatic improvement on SIGH-SAD and Beck Depression Inventory-Ⅱ. Adherence was measured using participant daily log. Participant groups were compared using t-tests, chi square, linear and logistic regressions. RESULTS: The study did not find any significant group difference between African-Americans and their Caucasian counterparts in adherence with light treatment as well as in symptomatic improvement.While symptomatic improvement and rate of treatment response were not different between the two groups,African-Americans, after adjustment for age, gender and adherence, achieved a significantly lower remission rate(African-Americans 46.3%; Caucasians 75%; P =0.02).CONCLUSION: This is the first study of light treatment in African-Americans, continuing our previous work reporting a similar frequency but a lower awareness of SAD and its treatment in African-Americans. Similar rates of adherence, symptomatic improvement and treatment response suggest that light treatment is a feasible, acceptable, and beneficial treatment for SAD in African-American patients. These results should lead to intensifying education initiatives to increase awareness of SAD and its treatment in African-American communities to increased SAD treatment engagement.In African-American vs Caucasian SAD patients a remission gap was identified, as reported before with antidepressant medications for non-seasonal depression, demanding sustained efforts to investigate and then address its causes.
文摘The optical absorption properties of femtosecond-laser-made ＂black silicon＂ as a function of the annealing conditions were investigated. We found that the annealing process changes the surface morphology and absorption spectroscopy of the ＂black silicon＂ samples, and obtained a maximum sub-band-gap absorptance value of approximately 30% by annealing at 1000 ~C for 30 min. The thermal relaxation and atomic structural transformation mechanisms are used to describe the lat- tice recovery and the increase and decrease of the substitutional dopant atom concentration in the microstructured surface during the annealing. Our results confirm that： i） owing to the ther- mal relaxation, the lattice defects decrease with the increase of the annealing temperature; ii） the quasi-substitutional and interstitial configurations of the doped atoms transform into substitutional arrangements when the annealing temperature increases; iii） the quasi-substitutional and intersti- tial configurations with higher energies of the doped atoms transform into interstitial configurations with the lowest energy after high-temperature annealing for a long period of time, causing the de- activation or reactivation of the sub-band-gap absorptance by diffusion. The results demonstrate that the annealing can improve the properties of ＂black silicon＂, including defects repairing, carrier lifetime lengthening, and retention of a high absorptive performance.
