Auditory feedback is required to maintain fluent speech. At present, it is unclear how attention modulates auditory feedback processing during ongoing speech. In this event-related potential (ERP) study, participants vocalized/a/, while they heard their vocal pitch suddenly shifted downward a ½ semitone in both single and dual-task conditions. During the single-task condition participants passively viewed a visual stream for cues to start and stop vocalizing. In the dual-task condition, participants vocalized while they identified target stimuli in a visual stream of letters. The presentation rate of the visual stimuli was manipulated in the dual-task condition in order to produce a low, intermediate, and high attentional load. Visual target identification accuracy was lowest in the high attentional load condition, indicating that attentional load was successfully manipulated. Results further showed that participants who were exposed to the single-task condition, prior to the dual-task condition, produced larger vocal compensations during the single-task condition. Thus, when participants’ attention was divided, less attention was available for the monitoring of their auditory feedback, resulting in smaller compensatory vocal responses. However, P1-N1-P2 ERP responses were not affected by divided attention, suggesting that the effect of attentional load was not on the auditory processing of pitch altered feedback, but instead it interfered with the integration of auditory and motor information, or motor control itself. Proficient motor control is achieved by using sensory feedback to plan, execute, and regulate motor movements The multiple resource theory of divided attention states that when performing two tasks simultaneously, the degree to which performance will decline on each task, compared to when each task is completed in isolation depends on: the resource demands of each of the two tasks, the similarity between the two tasks, and the allocation of resources between the two tasks The importance of auditory feedback for maintaining fluent speech has been demonstrated by individuals who have been deafened post-lingually, and experienced a gradual deterioration in the quality of their speech In addition to investigating vocal responses, auditory cortical responses to FAF recorded using electroencephalography (EEG) can provide information regarding the underlying neural mechanisms of speech motor control. The P1, N1, and P2 event-related potentials (ERPs) are reliably elicited by FAF Although it is unclear how FAF modulates these ERPs under divided attention, when elicited by other forms of auditory stimuli, auditory ERPs have shown sensitivity to divided attention. In particular, the N1 component is often enhanced when participants attend to an auditory stimulus, relative to passive listening of the same stimulus For the current experiment, we used a dual-task paradigm to investigate whether divided attention impacts the compensatory vocal responses and ERPs elicited by FAF. In order to reduce the allocation of attentional resources to auditory feedback during the FAF task, participants simultaneously monitored a rapid serial visual presentation (RSVP) of letters. The RSVP contained target letters, which participants identified and later reported. Attentional load was manipulated by varying the rate of the RSVP. Increasing the rate of the RSVP decreased the inter-stimulus interval (ISI) between letters, which modulated the perceptual load by increasing the number of stimuli. As a result of the increased number of stimuli, participants had to process more irrelevant information, which directly impacted the perceptual selection of relevant information, and thus increased the overall attentional demand of the task  participated. Vocal and behavioural responses were recorded from all 65 participants, while ERP responses were also recorded from a subset of 33 right-handed participants . All participants were Canadian-English speakers who did not speak a tonal language, with the exception of one participant who spoke a tonal language, but identified English as their primary language. This tonal language speaker did not show any differences in vocal compensations nor ERP responses to the FAF perturbations compared to the other non-tonal language-speaking participants. All participants also had normal or corrected to normal vision, had not been diagnosed with attention deficit (hyperactivity) disorder , epilepsy (or had a family history of seizures), visual deficits that could not be amended by corrective lenses, and did not have a speech or language disorder.Sixty-five participants between the ages of 16 and 38 years ; and 2. an “X,” that occurred pseudorandomly before or after the white letter. All letters in the stream were capitalized and in black font with the exception of the white target letter. Each letter was displayed at the same location in the center of a grey field, where the varied ISI was seen as a uniform grey field. For the single-task trials, each letter stream ended with a blank grey field.th and the 37th letter, and the “X” randomly occurred between the 1st and 15th letter before or after the white letter . Intermediate attentional load trials were 5.4 s in duration and consisted of 16 letters in the visual stream, with an ISI of 300 ms. The white letter appeared at random between the 4th and 16th place in the letter stream, while the “X” occurred at random between the 1st and 12th letter before or after the white letter (minimum 2nd letter and maximum 16th letter). Low attentional load trials were 5.5 s in duration, with 11 letters in the stream and an ISI of 500 ms. The white letter occurred randomly between the 4th and 11th place in the visual stream, and the “X” occurred at random between the 1st and 15th letters from the white letter . The presentation rate of the RSVP was manipulated to impose a high, intermediate, and low attentional load. The RSVP started with a green fixation cross that lasted for 750 ms, followed by a stream of successively presented letters. Each trial was approximately 5.5 s in duration. Each letter appeared for 50 ms, and each trial occurred with an ISI of either 100, 300, or 500 ms . High attentional load trials were 5.4 s in duration and consisted of 37 letters, with an ISI of 100 ms. The white letter appeared at random between the 4During the single-task condition, participants were instructed to attend to the RSVP, as the start of the RSVP was their cue to start vocalizing, and the termination of the RSVP was their cue to stop vocalizing. During the dual-task condition, participants were instructed to attend to the RSVP and monitor the letter stream for their cue to start and stop vocalizing, but also so they could identify two targets: a white letter, and an “X.” At the end of the letter stream, participants were required to answer two questions about the target letters. The first question appeared on the screen at the end of the trial and stated, “Identify the WHITE letter. If you are unsure, please guess.” The second question, which appeared immediately after the participant’s response to the first question stated, “indicate when the “X” appeared with reference to the white letter.” The participant was required to press a key labelled “YES” if they believed that the “X” appeared before the white letter, and a key labelled “NO” if the believed that the “X” appeared after the white letter. During each vocalization, the FAF perturbation occurred either 250–1000 ms before the “X,” or 100–1000 ms after the “X.” Emphasis was placed on both maintaining a steady vocalization and on responding accurately to the two questions at the end of the trial. Since participants could take as much time as they needed to respond to the two questions, participants moved on to subsequent trials at their own pace during the dual-task trials, whereas single-task trials occurred with an inter-trial interval of 3000 ms. The total duration of the experiment ranged from 40 to 60 minutes, and depended on the participant’s reaction time to the questions during the dual-task blocks, and the duration of breaks between blocks.Participants were seated 76 cm from a 15-inch LCD monitor in an electrically shielded booth  and were fitted with a HydroCel GSN 64 1.0 Cap , Etymotic ER-3 insert earphones , and an earset microphone . The presentation of visual stimuli and shift onsets and offsets were controlled by Max/MSP 6 . Keyed behavioral responses to questions were also recorded using Max/MSP 6, using a standard keyboard with labeled keys. During the experiment, voice signals were sent to a mixer , then to a digital signal processor , which altered the F0 of the voice signal. This process introduced a ∼10 ms delay in the feedback signal, that was then presented back to the participant through headphones as auditory feedback. The unaltered voice signal was digitally recorded  at a sampling rate of 44.1 kHz for later analysis.For each trial, records were kept of the trial’s attentional load condition, the white letter in the stream, whether the “X” appeared before or after the white letter, the participants’ keyed responses and reaction time to question one, as well as the participants’ keyed responses and reaction time to question two. Participants who did not answer either of the questions according to the instructions were excluded from the analysis. One participant’s answers were excluded from the white letter identification analyses for this reason. Accuracy and reaction time for questions one and two were averaged for each of the three categories of attentional load in the dual-task condition . Accuracy for high, intermediate, and low attentional load trials were then averaged across all participants for each question. Only accuracy data were examined since response accuracy was emphasized during the participant instructions.Each participant’s unaltered voice recording was segmented into separate vocalizations. The swipe algorithm Missing and incomplete vocalizations were excluded from the statistical analysis. Participants with more than 67%  rejected trials for any of the four attentional load conditions  were removed from further analysis. A total of 11 participants were excluded from the experiment due to F0 tracking issues. For the 54 remaining participants, an averaged F0 trace for retained trials was constructed for each of the four attentional load conditions. The average number of trials in each condition was 42 for the dual task-high, 40 for the dual task-intermediate, 41 for the dual task-low, and 39 for the single task attentional load trials. Traces were averaged across all participants, for each condition. For each participant, the magnitude of the compensatory response and the latency of the response were assessed. The amplitude of the compensatory response was determined by finding the maximum point at which the participants’ average F0 trace deviated from the baseline mean. Latency was determined as the time at which the maximum peak in the compensatory response occurred.EEG signals were recorded from 64-electrodes on the scalp, and referenced online to the vertex (Cz). Signals were bandpass filtered (1–30 Hz) and digitized (12-bit precision) at 1000 samples per second. Impedances were maintained below 50 kΩ for the experiment Six electrodes were included in the analysis: Fz, Cz, F3, C3, C4, and F4. These six electrodes were selected for analysis through visual inspection, having demonstrated the most robust P1-N1-P2 components, and based on previous research, which suggests that front-medial and centro-frontal regions display the most robust responses to pitch shifts Two separate repeated-measures analysis of variances (RM-ANOVAs) were conducted to look at the influence of attentional load  with block-order  as a between-subjects factor, on response accuracy for the identification of the white letter and the placement of the “X”. The Greenhouse-Geisser Two separate RM-ANOVAs were conducted to assess the influence of attentional load  and block-order  on vocal response magnitudes and response latencies. Follow-up RM-ANOVAs were run to investigate significant interactions. The Greenhouse-Geisser Separate two-way RM-ANOVAs were conducted to look at the impact of attentional load  and electrode site  with the between subject factor of block-order  on P1-, N1-, and P2- amplitudes, and P1-, N1-, P2- latencies. The Greenhouse-Geisser F = 78.662, p<0.001, η2 = 0.607, where white-letter identification was significantly more accurate for the dual-task low attentional load condition, relative to the dual-task high attentional load condition, p<0.001. While the dual-task intermediate attentional load condition also elicited higher response accuracy for the white-letter identification, relative to the dual-task high attentional load condition, p<0.001  = 0.686, p = 0.411, η2 = 0.013, and the interaction between attentional load and block-order were not significant, F = 0.107, p = 0.819, η2 = 0.002.A RM-ANOVA was conducted to look at the effect of attentional load on white-letter identification accuracy with block-order as a between subjects factor. There was a main effect of attentional load, .001 see . The maiF = 106.443, p<0.001, η2 = 0.672, where accuracy was much higher for the dual-task low attentional load condition, compared to the dual-task intermediate, and dual-task high attentional load conditions, p<0.01. In addition, “X”-placement accuracy was also greater for the dual-task intermediate attentional load condition, compared to the dual-task high attentional load condition, p<0.001  = 0.159, p = 0.691, η2 = 0.003, and the interaction between attentional load and block-order were not significant, F = 2.454, p = 0.107, η2 = 0.045.A RM-ANOVA was conducted to look at the effect of attentional load on “X”-placement accuracy, with block-order as a between subjects factor. There was a main effect of attentional load, .001 see . The maiPearson-product moment correlations were conducted to look for potential relationships between the magnitude and latency of vocal responses, and the accuracy with which the white-letter and “X”-placement were identified, for the dual-task high, dual-task intermediate, dual-task low attentional load conditions. The correlations between white letter identification accuracy and vocal response magnitude, and white letter identification accuracy and vocal response latency, were not significant, both p>.05. Similarly, the correlations between accuracy for “X”-placement and vocal response magnitude, and accuracy for “X”-placement and vocal response latency, were also not significant, both p>.05.F = 1.175, p = 0.321, η2 = 0.022  = 0.573, p = 0.453, η2 = 0.011. However, a significant interaction was found between attentional load and block-order, F = 5.782, p = 0.003, η2 = 0.1  = 7.303, p = 0.001, η2 = 0.207, where the vocal response magnitudes were significantly larger in the single-task condition, compared to all attentional load conditions, p<0.02. However, the effect of attentional load on vocal response magnitudes in the dual-task first condition was not significant, F = 1.083, p = 0.362, η2 = 0.043.A RM-ANOVA was conducted looking at the effect of attentional load on vocal response magnitudes, with block-order as a between subjects factor. The main effect of attentional load on vocal response magnitudes was not significant, .022 see , nor was 0.1 see . Follow-p = 0.173, η2 = 0.031, nor was the main effect of block-order, F = 0.542, p = 0.465, η2 = 0.01, or the attentional load by block-order interaction F = 0.739, p = 0.53, η2 = 0.014.A RM-ANOVA was conducted to look at the effect of attentional load on vocal response latencies, with block-order as a between subjects factor. The main effect of attentional load was not significant, F = 1.684, See F = 1.438, p = 0.238, η2 = 0.054, no main effect of electrode site, F = 1.375, p = 0.261, η2 = 0.052, and no main effect of block-order, F = 0.009, p = 0.926, η2<0.001. The attentional load by block-order interaction was also not significant, F = 0.979, p = 0.407, η2 = 0.038, as was the electrode site by block-order interaction, F = 2.067, p = 0.15, η2 = 0.076, the attentional load by electrode site interaction, F = 0.281, p = 0.945, η2 = 0.011, and the three-way interaction between attentional load, electrode site, and block-order, F = 0.853, p = 0.531, η2 = 0.033.A RM-ANOVA was conducted to look at the effect of attentional load, electrode site, and block-order on P100 amplitudes. There was no main effect of attentional load, F = 1.349, p = 0.265, η2 = 0.051, no main effect of electrode site, F = 0.299, p = 0.695, η2 = 0.012, and no main effect of block-order, F = 0.885, p = 0.356, η2 = 0.034. The attentional load by block-order interaction was not significant, F = 0.034, p = 0.992, η2 = 0.001, as was the electrode site by block-order interaction, F = 0.753, p = 0.45, η2 = 0.029, the attentional load by electrode site interaction, F = 0.338, p = 0.916, η2 = 0.013, and the three-way interaction between attentional load, electrode site, and block-order, F = 1.246, p = 0.286, η2 = 0.047.A RM-ANOVA was conducted to look at the effect of attentional load, electrode site, and block-order on P100 latencies. There was no main effect of attentional load, F = 2.05, p = 0.114, η2 = 0.076, nor a significant main effect of block-order, F = 1.065, p = 0.312, η2 = 0.041. However, the main effect of electrode site was significant, F = 4.057, p = 0.023, η2 = 0.14, such that the right electrode site recorded smaller N1 amplitudes  than the medial electrode site, p<0.01  = 1.22, p = 0.308, η2 = 0.047, as was the electrode site by block-order interaction, F = 0.747, p = 0.479, η2 = 0.029, the attentional load by electrode site interaction, F = 0.795, p = 0.523, η2 = 0.031, and the interaction between attentional load, electrode site, and block-order, F = 0.989, p = 0.413, η2 = 0.038.A RM-ANOVA was performed to look at the effect of attentional load, electrode site, and block-order on N100 amplitudes. There was no significant main effect of attentional load, 0.01 see . FurtherF = 0.588, p = 0.625, η2 = 0.023, no main effect of electrode site, F = 1.367, p = 0.265, η2 = 0.052, and no main effect of block-order, F = 2.225, p = 0.148, η2 = 0.082. Furthermore, the attentional load by block-order interaction was not significant, F = 1.061, p = 0.371, η2 = 0.41, nor was the electrode site by block-order interaction, F = 2.644, p = 0.081, η2 = 0.096, the attentional load by electrode site interaction, F = 1.534, p = 0.195, η2 = 0.058, and the interaction between attentional load, electrode site, and block-order, F = 1.649, p = 0.164, η2 = 0.062.A RM-ANOVA was performed to look at the effect of attentional load, electrode site, and block-order on N100 latencies. There was no main effect of attentional load, F = 0.603, p = 0.615, η2 = 0.024, no main effect of electrode site, F = 2.013, p = 0.144, η2 = 0.075, and no main effect of block-order, F = 0.016, p = 0.9, η2 = 0.001. The attentional load by block-order interaction was nonsignificant, F = 0.055, p = 0.983, η2 = 0.002, as was the electrode site by block-order interaction, F = 2.259, p = 0.115, η2 = 0.083, the attentional load by electrode site interaction, F = 0.311, p = 0.93, η2 = 0.012, and the three-way interaction between attentional load, electrode site, and block-order, F = 1.354, p = 0.237, η2 = 0.051.A RM-ANOVA was conducted to look at the effect of attentional load, electrode site, and block-order on P200 amplitudes. There was no main effect of attentional load, F = 2.066, p = 0.112, η2 = 0.076, no main effect of electrode site, F = 0.991, p = 0.378, η2 = 0.038, and no main effect of block-order F = 1.181, p = 0.288, η2 = 0.045. Furthermore, the attentional load by block-order interaction was not significant, F = 1.294, p = 0.283, η2 = 0.049, as was the electrode site by block-order interaction, F = 0.204, p = 0.816, η2 = 0.008, the attentional load by electrode site interaction, F = 0.369, p = 0.898, η2 = 0.015, and the interaction between attentional load, electrode site, and block-order, F = 0.802, p = 0.57, η2 = 0.031.Similar results were obtained from the RM-ANOVA performed to determine whether an effect of attentional load and electrode-site, with block-order as a between-subjects factor, existed for the latency of the P200. There was no main effect of attentional load, The aim of this study was to investigate whether increases in attentional load modulate vocal and neural responses to FAF perturbations. Participants produced vocalizations while exposed to FAF in both single and dual-task conditions. To manipulate participants’ attentional load, participants produced vocalizations while they either passively viewed a RSVP of letters, or while they attended to a RSVP of letters that was either presented at a low, intermediate, or high rate, in order to later identify target stimuli. A main effect of attentional load on both white letter identification accuracy, and “X”-placement accuracy was found, as target identification was better following the dual-task low and dual-task intermediate attentional load trials, relative to the dual-task high attentional load trials. These results suggest that the participants’ attentional load was successfully manipulated by increasing the stimulus presentation rate. Despite the differences in accuracy found across the different presentation rates, even in the highest attentional load condition participants accurately identified the white letter 87.5% of the time, while the “X”-placement was correctly identified 78.2% of the time. The high level of accuracy found even in the most attentionally demanding condition, suggests that while the attentional load manipulation was successful, participants were still able to maintain a high level of performance.Examination of speakers’ compensatory responses to the brief FAF perturbations revealed that vocal response magnitudes were modulated by an attentional load by block order interaction. Participants who were exposed to the single-task condition, prior to the dual-task condition, produced larger vocal responses in the single-task condition, relative to the dual-task condition. However, participants who were exposed to the dual-task condition, prior to the single-task condition, produced similar vocal responses in both conditions. This interaction suggests that when participants completed the single-task prior to the dual-task, they were able to passively view the visual stream during the single-task, with sufficient attentional resources remaining to monitor their auditory feedback and correct for production errors. In contrast, when attentional resources were then split between the vocalization task and the target identification task, fewer attentional resources were available for participants to monitor their auditory feedback, resulting in smaller vocal responses. Although divided attention modulated responses to FAF when the single-task condition occurred prior to the dual-task condition, this was not the case when the dual-task condition occurred prior to the single-task condition. When the dual-task condition was completed prior to the single-task condition, vocal responses in the single-task condition were no different than those in the dual-task condition. We suggest that when participants were exposed to the dual-task, prior to the single-task, the single-task demanded more attentional resources as participants were unable to passively view the visual stream. Previous research has shown that extensive and consistent training on a task can lead to automatic processing of stimuli The results of this study suggest that when attention is divided, smaller vocal responses to FAF are produced. One possible explanation for these smaller responses is that under divided attention auditory feedback is less salient. Previous research has shown that under visual attentional load, the loudness of tones is attenuated by 7 dB Although the size of the vocal responses to FAF were modulated by divided attention, vocal response latencies were not. We hypothesized that increasing attentional load would increase the processing demands of the visual task, and reduce the amount of attentional resources allocated to the processing of auditory feedback, resulting in later vocal responses. Although it is possible that vocal response latency is not affected by divided attention, it is also possible that the attentional load manipulation was not strong enough to affect the vocal response latencies recorded in this study. As previously mentioned, response accuracy was quite high, even for the highest level of attention load. This being said, while it appears as though attention can be divided without influencing the timing of vocal responses, this may not be the case in situations where attentional resources are more heavily taxed.Divided attention resulted in the modulation of compensatory vocal responses to FAF; however, divided attention did not modulate the amplitude or latency of the P1-N1-P2 ERP components elicited by the FAF in this study. Although vocal responses were smaller under divided attention, they were still produced. This suggests that the FAF perturbations were detected by the auditory system in both the single- and dual-task conditions. Based on these results, we suggest that the effect of attentional load was not on the auditory processing of FAF, but instead it interfered with the integration of auditory and motor information, or motor control itself. It has previously been suggested that speech motor control may be disrupted under divided attention. For example, when participants were required to read sentences while also completing a secondary motor task, divided attention resulted in decreased displacement and velocity of labial movements Even though divided attention was not found to modulate ERP responses to FAF, the amplitude of the N1 component was found to vary as a function of electrode site. N1 amplitudes were smaller  at the right electrodes sites, relative to medial electrode sites. This result is unsurprising, as N1 responses elicited by FAF are generally largest at medial sites Much like the size of the ERPs elicited by the FAF perturbations, and the vocal response latencies, the latencies of the ERP components were not found to differ when attention was divided. We hypothesized that divided attention may result in later ERP latencies as a result of increased processing demands. Although this hypothesis was not confirmed, it is possible that the dual-task condition was not demanding enough to increase processing demands to the extent that ERP latencies were affected. As mentioned previously, even during the most demanding attentional load condition, accuracy was still quite high, thus a more demanding task may be required to produce changes in ERP latencies as a function of attentional load.Fluent speech production relies on auditory feedback for the regulation of ongoing and future speech motor commands. The aim of the current study was to investigate how attention modulates the processing of auditory feedback during ongoing speech. The results of this study suggest that divided attention can reduce the size of compensatory motor responses to FAF. However, the results of this study also suggest that the P1-N1-P2 ERP components elicited by FAF are less sensitive to divided attention. While the attentional load manipulation utilized in this study was successful at reducing target identification accuracy as the attentional load increased, accuracy was still quite high, even at the highest level of attentional load. With this being said, it is possible that auditory-cortical responses are less sensitive to increases in attention load, but may show attentional modulation if a secondary task is utilized that imposes a higher attentional load. Alternatively, sensorimotor integration, or motor control itself, may be more susceptible to increases in attentional load.Throughout a typical day, we often encounter situations where we must speak while also performing other tasks. Recently, there has been a focus on assessing the impact of conversation on the performance of secondary tasks such as driving. We instead assessed the impact of divided attention on low level control of speech and found that our ability to use auditory feedback to monitor and regulate our speech may be compromised during many of our daily encounters. While typically developed adults have internal models that can execute fluent speech in a feedforward manner, previous research has suggested that children rely more on auditory feedback


Spain’s financial crisis has been characterized by an increase in unemployment. This increase could have produced an increase in deaths of women due to intimate partner-related femicides (IPF). This study aims to determine whether the increase in unemployment among both sexes in different regions in Spain is related to an increase in the rates of IPF during the current financial crisis period.An ecological longitudinal study was carried out in Spain’s 17 regions. Two study periods were defined: pre-crisis period (2005–2007) and crisis period (2008–2013). IPF rates adjusted by age and unemployment rates for men and women were calculated. We fitted multilevel linear regression models in which observations at level 1 were nested within regions according to a repeated measurements design.Rates of unemployment have progressively increased in Spain, rising above 20 % from 2008 to 2013 in some regions. IPF rates decreased in some regions during crisis period with respect to pre-crisis period. The multilevel analysis does not support the existence of a significant relationship between the increase in unemployment in men and women and the decrease in IPF since 2008.The increase in unemployment in men and women in Spain does not appear to have an effect on IPF. The results of the multilevel analysis discard the hypothesis that the increase in the rates of unemployment in women and men are related to an increase in IPF rates.The decline in IPF since 2008 might be interpreted as the result of exposure to other factors such as the lower frequency of divorces in recent years or the medium term effects of the integral protection measures of the law on gender violence that began in 2005. The world economic crisis that broke out at the end of 2007 severely affected the banking sector. In Spain, banks stopped lending credit to companies and individuals, giving rise to dramatic destruction of jobs. For this reason rates of unemployment rose from 13.9 % in the year 2008 to 26.2 % in 2013 [It is known that mortality rates in countries facing financial crisis have changed historically with respect to periods of economic growth. Currently, death rates seem to be decreasing in several of these countries in crisis, but causes of mortality behave differently –6. When Our hypothesis in this article is that in the current financial crisis period in Spain, the massive destruction of employment for both men and women could favor or promote a change in homicides of women due to intimate partner violence, also known as intimate partner-related femicides (IPF). As has been observed in other studies, when comparing perpetrators of femicide with other abusive men, unemployment appears to be a significant demographic factor even after controlling for other relevant characteristics –19. As oThis study aims to explore how the increase in unemployment among both sexes in the different Spanish regions is related to rates of IPF during the current period of financial crisis. Prior studies showed differences in IPF among the different Spanish regions, which shows that it is important to take geographic distribution into account in the analysis of IPF in Spain –29.An ecological longitudinal study was carried out in 17 Spanish regions- Autonomous Communities- in the period 2005 to 2013. The autonomous cities of Ceuta and Melilla were excluded from the analysis because they are not comparable with the other regions studied, given that they are autonomous cities and not regions. Two periods were defined, considering 2008 as the year of the beginning of the economic crisis [The data on the number of IPF were collected from the Federation of Separated and Divorced Women, whose website has collected and published the cases of IPF for ages 15 and over since the year 1998 . OfficiaThe authors confirmed that 100 % of the deaths recorded by official government sources in Spain during the study period appear in the database of the Federation of Separated and Divorced Women. The Federation of Separated and Divorced Women was founded in 1973. Their activities included the defense of equal rights among men and women and recognition of women’s rights in order to eradicate discrimination in Spanish society. The Federation’s web page records all IPF related deaths in Spain. The authors reviewed this information and added cases to their own database. They double-checked later on that the number of annual deaths due to IPF recorded by the Federation equaled the number of deaths published by official sources such as the Ministry of Equality. The only difference between the two sources was that the information recorded by the Federation is disaggregated. Previous studies show similar percentages of overlap between the database of the Federation of Separated and Divorced Women and the National Observatory on Violence against Women of the Spanish government , 29, 31.Unemployment data were obtained from the Labor Force Survey (LFS) conducted by the National Institute of Statistics of Spain (INE). Unemployment data are collected each trimester through questioning a wide representative sample of the Spanish population about their employment situation during the past weeks. This is the most reliable data to measure unemployment in Spain. An unemployed person is defined as “16 years and over who, during the survey week, was without work, was available for work and actively seeking employment” [The dependent variable was the annual rate of IPF in the 17 Spanish regions adjusted by age. The independent variable considered was the annual unemployment rate (men and women) in the 17 Spanish regions during the study period. The denominator for calculating unemployment rates was the total labor force . AnotherFinally, for the multilevel regression study, a dummy variable was created taking the value of 1 in a period of crisis (2008–2013) and 0 otherwise. Thus it is possible to observe the probability of variation in IPF between the two periods.We calculated crude annual unemployment rates for men and women and age-adjusted rates of Intimate Partner-related Femicide for the years 2005 through 2013 . With respect to unemployment data, in period 1 the unemployment rate ranged from 3.79 to 10.20 % for men and from 7.2 to 20.1 % for women. In period 2 the unemployment rate for men ranged from 11.18 to 27.5 %, while for women rates ranged from 12.4 to 30.9 %. Finally, the percentages of foreign population observed in period 1 ranged from 2.11 to 14.11 %. For period 2, these percentages ranged from a minimum of 3.01 % to a maximum of 18.54 % . In neither of the two models was the percentage of immigrant population significant, nor was the period of crisis, in explaining IPF  . HegemonAdditionally, it must be taken into account that in Spain the number of divorces and separations decreased by 19.18 % between 2005 and 2012 . DivorceIt is also possible that there is an explanation related to the measures for integral protection against gender violence laid out by Organic Law 1/2004 . In the The low number of cases of IPF in years studied may have influenced our results. As has been mentioned in previous studies, there is no established date for the start of the financial crisis in Spain . HoweverIn Spain there has been an increase in male and female unemployment rates as a consequence of the economic crisis, there has also been a decrease in IPF rates. It does not seem that unemployment has influenced the observed tendency of IPF, which should therefore be attributed to exposure to other factors such as the decrease in divorce or the protective effects of the gender violence law in effect prior to the beginning of the crisis. However, the decrease in IPF could be related to an increase in invisible IPV cases. Therefore, it is important to continue this line of research with other studies that contemplate other IPV outcomes such as calls to help lines or filing formal police reports. It would also be interesting to analyze the situation in other countries where the government response to the financial crisis has been different.


It is believed that at low hydrogen flow, those remained oxygen or other oxidizing impurities make the graphene films p-doped and result in decreasing the carrier mobility.Hydrogen flow during low pressure chemical vapor deposition had significant effect not only on the physical properties but also on the electrical properties of graphene. Nucleation and grain growth of graphene increased at higher hydrogen flows. And, more oxygen-related functional groups like amorphous and oxidized carbon that probably contributed to defects or contamination of graphene remained on the graphene surface at low H Hydrogen plays a dual role during growth on copper (Cu) substrate [2, methane (CH4) used as a carbon precursor should chemisorb on the Cu surface to form active carbon species, that is, (CHx)s (x = 0 ~ 3), which subsequently react to form graphene. However, such dehydrogenation reactions are not thermodynamically favorable even on Cu surface [2 more readily dissociates on Cu and produces active H atoms [4, and lead to production of surface bound (CH3)s, (CH2)s, or (CH)s radicals. It also controls the grains' shape and dimension by etching away the weak carbon-carbon bonds [2 gas during growth steps affects the morphology of graphene film such as the sizes, shapes, and dimensions of graphene grain boundaries  [Since the first report of the special characteristics of graphene, a planar sheet of sp physics ,2 to the physics , photovo physics , or micr physics -9. Howev physics ,11, alth physics -14. One  physics -18. Espe physics . To obtaubstrate . Without surface . Molecul H atoms . These Hon bonds . So, cha zigzag) ,22.2 flow during the low pressure CVD also had significant effect on the electrical properties of graphene. We found that in our process conditions, H2 seemed to act more like as a nucleation/growth promoter and a defect suppressor  of CVD-grown graphene film in our process conditions.In this article, we observed that the H2 and argon (Ar) atmosphere at 950°C for 15 min. The Ar flow was set at 100 sccm during the annealing step for all the samples. After that, CH4 gas was forced to flow at 100 sccm during the growth step, and the H2 flow was systematically (10 to 500 sccm) varied for different samples. Then, the chamber was cooled down to room temperature without H2 and CH4 flows. Table 2/Si substrate and put into acetone for 10 h to dissolve PMMA. All the samples were thermally annealed after transferring to the SiO2/Si substrate under nitrogen gas protection for further characterization. The as-grown and transferred films were characterized by field emission scanning electron microscopy  to check the proper growth of the graphene film. Raman spectra were recorded using a Renishaw Raman microscope  with an Ar laser wavelength of 514 nm, and X-ray photoelectron spectroscopy  was used to confirm the quality of the film. The atomic force microscopy (AFM) was done to analyze the morphology of grown films, grain boundaries, and thickness using the commercial AFM n-Tracer . Electrical contacts were made by thermally evaporating Au/Cr with thickness of 30/5 nm for transport measurements.Graphene samples of various sizes (ranging from 1 × 1 to 3 × 3 cm) were grown on Cu foils  purchased from Sigma-Aldrich . The Cu foil substrate was ultrasonically degreased by being immersed in acetone, methanol, isopropyl alcohol (IPA) solution, and deionized (DI) water and then dried and baked for 5 min. After the foil was placed in a quartz chamber, the chamber was evacuated and heated up to 950°C very rapidly using halogen lamps. Annealing was performed under H2 flow of 10, 100, 200, 300, 400, and 500 sccm at four different growth durations of 1, 5, 10, and 15 min. Figure 2 flow rates of 10 (low H2 flow) and 400 sccm (high H2 flow). The corresponding growth schematics during each elapse time are shown in Figure A large number of graphene samples were prepared, corresponding to the H2 flow rate (10 sccm), no nucleation occurs for smaller growth durations, e.g., t < 5 min. The spontaneous nucleation and subsequent growth of graphene occurs only when a critical level of supersaturation is reached. At lower H2 flow rates and hence at low partial pressure, this critical level of supersaturation is achieved only at longer growth durations. As the H2 flow rate increases, this threshold of supersaturation is achieved at relatively shorter growth durations. Further, our results also suggest that as the H2 flow increases the density of nuclei increases , the nucleation and growth are reduced significantly, as compared in Figure 2 partial pressure, the graphene domain feature irregular shapes [As shown in Figure low rate 0 sccm, nlow rate 0 sccm, nlow rate 0 sccm, nlow rate 0 sccm, nr shapes . The dom2 flow (10 to 500 sccm) at a growth time of 15 min. As can be observed from Figure 2 flow increases from 10 to 500 sccm, the intensity of defect peak in the Raman spectra decreases and is finally unnoticeable for 500 sccm of H2, indicating that the quality of grown graphene increases with increasing H2 flow. The D peak is located at approximately 1,350 cm−1, attributed to the breathing mode of sp2 atoms, and originated by the existence of some defects such as edges, grain boundaries, functional groups, or structural disorders [−1, respectively. The G peak becomes sharp, and the D peak shows high intensity. While for the sample grown at high H2 flow (500 sccm), the peak positions of G and 2D are red shifted to around 1,585 and 2,683 cm−1, respectively, as can be observed in Figure 2 flow, as can been seen in Figure 2. The FWHM of 2D peak is 28 to 39 cm−1 for all the samples, as can be seen in Figure ID/IG ratio decreases from 0.42 to 0.08, whereas the I2D/IG ratio increases from 1.0 to 1.7 with increase of H2 flow from 10 to 400 sccm as can be presented in Figure 2 in Cu is 2 × 10−4 cm2s−1. H2 or atomic H can easily diffuse into the catalyst and compete with CH4 for chemisorption; H2 can also contribute to the fast removal of residual oxygen and contaminants from the surface [2 effects seem to be beneficial in improving the qualities of graphene in our process conditions.To check the crystallinity of graphene, we used Raman spectroscopy on all the prepared samples corresponding to Hisorders . As for  surface . These H−1, while G peaks appeared between 1,597 to 1,606, 1,592 to 1,601, and 1,580 to 1,589 cm−1 for samples at 10, 200, and 500 sccm of H2 flow, respectively  and carbonyl C = O and carboxylic COOH (288.3 to 288.7 eV) groups [2 hybridization is attributed to the carbon lattice, while sp3 is a result of oxygen-related functional groups like amorphous and oxidized carbon that probably contributed to defects or contamination [2 flow (500 sccm) shows higher sp2/sp3 peak ratio than that grown at 10 sccm in Figure 2 is observed at 284.6 eV with FWHM of 0.69 eV, while sp3 peaks at hydroxyl C-OH and carboxylic COOH are at 285.3 and 288.1 eV, respectively. As for the sample grown at low H2 flow (10 sccm), the sp2/sp3 ratio decreases significantly, and sp2 peak is broadened, which reveals that graphene is oxidized and amorphized at the low H2 atmosphere. It is also thought that residual oxygen or oxidizing impurities [2 atmosphere.C1s XPS spectra display an asymmetric shape typical of graphitic sp) groups ,30. The mination . The sampurities , which a2. Panels in Figure 2 each for a growth time of 15 min. As can be observed from the topography maps  under different H2 flows. In principle, the charge neutrality point (CNP) should be at Vg = 0 if the graphene is undoped [ne = Cg(Vg − VDirac), where Cg is the gate capacitance for a SiO/Si substrate [μ = (enρ)− 1.To further confirm the quality of the graphene films, charge transport measurements were performed. Figure  undoped ,34. The ubstrate . In orde2 flow rate. For the sample grown under 10 sccm of H2 flow, the CNP was at +31 V, but for the sample under 500 sccm H2 flow, the CNP was shifted to +10 V. Our results show that at low H2 flow all the film exhibited p-typed behavior [2 flow, the synthesized graphene becomes closer to a pristine graphene, and its mobility increases. Figure 2 flow. The changes in charge carrier density of graphene layers are related with changes in Fermi level of graphene layers. Thus, different H2 flow significantly modulates the Fermi level of graphene layers. The defects of graphene, which can be originated from the inevitable occurrence of residual oxidizing impurities in the chamber's atmosphere and gas feedstock, are suppressed under high H2 flow rate.In the experiments, more than six devices were made. There is a trend in which the mobility of the graphene increases and the CNP shifts toward zero with increasing Hbehavior . With th2 flow and is in good agreement with that reported for a monolayer graphene (97.1%), indicating all monolayer graphene films as confirmed from the AFM topography [The optical transmittance spectra as depicted in Figure pography . Our res2 flow conditions. It is believed that at low hydrogen flow, those remained oxygen or other oxidizing impurities make the graphene films p-doped and result in decreasing the carrier mobility. In our process conditions, H2 seemed to act more as a nucleation/growth promoter and a defect suppressor  of CVD-grown graphene film.In conclusion, we observed that hydrogen flow during the low pressure chemical vapor deposition had significant effect not only on the physical properties but also on the electrical properties of graphene. Nucleation and grain growth of graphene increased at higher hydrogen flows. And, more oxygen-related functional groups like amorphous and oxidized carbon that probably contributed to defects or contamination of graphene remained on the graphene surface at low HThe authors declare that they have no competing interests.SH and JP performed the experiments. MI, MA, JS, and JE analyzed the data. SH and JJ wrote the paper. All authors read and approved the final manuscript.


With much improved h-BN-tunneling-junction stability, we are able to probe all possible phonon modes of h-BN and graphite/graphene at Γ and K high symmetry points by inelastic tunneling spectroscopy. Additionally, we observe that low-frequency out-of-plane vibrations of h-BN and graphene lattices are significantly modified at heterostructure interfaces. Equipped with an external back gate, we can also detect high-order coupling phenomena between phonons and plasmons, demonstrating that h-BN-based tunneling device is a wonderful playground for investigating electron-phonon couplings in low-dimensional systems.Inelastic electron tunneling spectroscopy is a powerful technique for investigating lattice dynamics of nanoscale systems including graphene and small molecules, but establishing a stable tunnel junction is considered as a major hurdle in expanding the scope of tunneling experiments. Hexagonal boron nitride is a pivotal component in two-dimensional Van der Waals heterostructures as a high-quality insulating material due to its large energy gap and chemical-mechanical stability. Here we present planar graphene/ Especially in low-dimensional systems such as graphene- and carbon nanotube-based devices, electron-phonon scattering has been considered as the major source for limiting conductivity178h-BN) has been acclaimed as a superb gate-insulating material for low-dimensional electronic and optical devices with graphene121617h-BN and its hybrid structures are greatly needed, not only for understanding physical properties of h-BN-based nanoscale devices but also for developing new electronic and optical devices. Although there are several experimental and theoretical reports on h-BN phonons192021222324h-BN-based heterostructures are sparse with a few of experimental reports on Raman-active E2g phononsh-BN relied on optical methods due to a large band gap (≈6 eV) of h-BNHexagonal-boron nitride  finding good agreement with experimental data. Finally, we are able to identify charge-density-dependent excitations with energies higher than 200 meV, suggesting that the overtone excitations can be due to multi-phonon scattering processes combined with charge-density-dependent excitations, plasmonsIn this article, we present electron-tunneling spectroscopy measurements of gated single-layer graphene devices with a thin tructure . In our h-BN-based tunneling devices with both thick h-BN (>20 nm) and SiO2 (300 nm) as gate insulators, and a doped Si substrate as bottom gate. Sample bias (Vb) is applied to the top probe, and tunneling current as well as differential conductance (G = dI/dVb) are monitored through the graphene layer. We use a thick-and-narrow graphite flake as the tunneling probe, which shows superior tunneling characteristics to metal electrodes3334The inset of T = 5.9 K. We apply small AC-excitation voltage  to DC sample bias and measure both I-Vb  of graphene is expected to be at gate voltage Vg = −40 V and the dip at the Fermi level, EF (Vb = 0 mV). Additionally, we can find several kinks in dI/dVb around EF within |Vb| ≤ 200 mV. These features become more prominent in the IETS signal dG/dVb  and Vg = 50 V to 40 V  with a spacing of ΔVg = 2 V. Without any difficulties, we can identify that there exists two types of tunneling features, with and without density dependence. As expected, the feature related to ED changes its position upon varying charge density, as marked with red dotted arrows. However, most spectra features within |Vb| ≤ 200 mV barely change their positions in sample bias with a little variation in intensity even though charged carriers switch polarity from electrons to holes in the full range of gate voltages, −50 V ≤ Vg ≤50 V.To analyze spectrum features in detail, we obtain a series of tunneling spectra while varying the charge density with Vg and Vb reveals a plethora of electronic structures not just limited to EF but also extended to both empty (Vb >0 mV) and filled (Vb <0 mV) states. In the |dG/dVb| gate mapping  state obtained from Vg = 10 V to Vg = 50 V are also plotted  of h-BN, which is Raman-active E2g phonon at the frequency of ≈1365 cm−1 (≈169 meV)19Γ3− (or Γ4+) (ZO) and acoustic Γ4+ (ZA) phonon modes can be assigned to the peaks at P6 (≈103 meV) and P1 (≈17 meV), respectively. We can argue that Γ4+ phonon mode  becomes hardened because 4-layer h-BN is encapsulated with relatively thick top graphite probe and bottom h-BN gate insulators. We can recognize several K-point phonon modes as well: in-plane optical K1,2  and K5 , in-plane acoustic K5  and K1,2 , and out-of-plane optical K6  and acoustic K6  phonon modes. Note that some of phonon modes especially out-of-plane acoustic K6 (ZA) phonons are slightly off from theoretical expectations, which we relate to graphene/h-BN heterostructures. We will discuss how these phonon modes are influenced by nearby layers later. In addition, we tend to assign the peak at ≈186 mV  to the overbending mode of the in-plane optical  phonons of h-BN, as marked with a red star in et al.h-BN crystals at the frequency of 1470 cm−1 (≈182 mV) with resonant Raman measurements, and Kern et al.−1, 185 mV) of LO-phonon branch is formed not at the high symmetry point of Γbut in between Γ and K resulting LO-overbending branch.First, we compare our data with DFPT-calculated phonon dispersions of 4-layer h-BN , which hh-BN . As indiV P10 in  is attriΓ and K: in-plane optical Γ5+  and out-of-plane optical Γ4+  phonon modes, and in-plane optical K1,2  , K5 , and in-plane acoustic K2  phonon modes along with out-of-plane optical/acoustic K6  phonon modes. It is worth mentioning that phonon dispersions for graphite and single-layer graphene are almost identical (Γ6− (or Γ2−)  phonon mode which is solely ascribed to the layered structure of graphite. Note that several excitations could have contributions from both h-BN and graphite/graphene phonons because of the structural similarity of h-BN and graphite/graphene. However, the peak at ≈199 mV (P12) are exclusively from the Γ5+phonon mode of graphite/graphene, which is Raman-active E2g phonon (G peak) at ≈1580 cm−1 (≈196 meV)Γ pointAs mentioned previously, we employed graphite flake as a tunneling probe, therefore we can expect that our data should have signatures of graphite phonons. Indeed, we can identify several graphite phonons at the high symmetry points of dentical . Thus, wΓ4+ ZO, P phonon mM are missing differing from the previous IETS studies with STM tunneling measurements1011M2+ phonon  mode. For example, M3− phonon  mode of graphite/graphene marked with a black star in M3− phonons are observed. Additionally, M3+ phonon  mode, one of the conspicuous phonons with large density-of-states (DOS), is missing in our IETS measurements. M-phonon suppression is observed in h-BN phonons as well. Based on DFPT calculation  and M (M2+) points, which could be linked to the excitation at ≈156 meV (P9). However, the strongest IETS signal in our devices is from the Γ5+ phonon mode at ≈168meV, which has considerably lower phonon DOS compared to other M-point phonons (M2+ (or M3−) phonon (TA) mode at ≈68 meV is also missing in the tunneling spectra given the fact that the excitation at ≈67 meV (P4) is the weakest IETS feature . Even though electrons require momentum change  to interact with phonons at the K point, the electron-phonon scattering rate for the phonons at K point could be higher than the case for M-point phonons, which require multiple electron-phonon scatterings. Note that the excitation at ≈84 meV (P5), which we tentatively assign to the M2+ phonon (ZO) mode, is one of the broadest excitations among twelve peaks with ≈18 mV FWHM. Here, we conclude that the tunneling in our planar h-BN junctions would be less susceptible to momentum-changing scattering events, especially parallel momentums during tunneling process, contrast with STM measurements in which one electrode is an atomically sharp non-planar metal tip, which breaks parallel-momentum conservation71011In both graphene and graphite, all available electronic states of tunneling electrons are located in the vicinity of the h-BN layers form heterostructure, it is expected that the lattice dynamics of graphene and h-BN, especially low-frequency out-of-plane modes, are influenced by the nearby layers. Indeed, we find that graphene/h-BN heterostructure shows phonon dispersions different from those of free-standing graphene and h-BN. h-BN heterostructure. For the sake of simplicity, we consider single-layer graphene is aligned on top of h-BN layer in an AA stacking, with graphene atoms (unit length: 0.245 nm) relaxed to h-BN lattice (unit length: 0.251 nm). To compensate the lattice deformation (strains) due to the structural mismatch, we calculate Grüneisen parameters for free-standing graphene and h-BN, and obtain the phonon modes of the unstrained graphene/h-BN heterostructure (h-BN becomes hardened shifting K6 phonon (ZA) mode to higher frequency (≈46 meV), which can be assigned to the previously-unassigned peak at ≈47 mV (P3). Second, out-of-plane acoustic Γ6−(or Γ2−) phonon (ZA) mode of graphene is blue-shifted to a frequency of ≈36 meV (P2). Third, M2+phonons (ZO) of graphene become hardened, shifting closer to the experimental data at ≈86 meV (P5). Last, graphene LA-phonon branch becomes slightly softened, moving K5 phonons closer to the peak at ≈140 meV (P8).When graphene and tructure   = Ei + α exp^(β Vg), and find E1 ≈ 214 mV (E2* ≈ −201 mV) for the empty (filled) state excitation in a and b, obtaining E2 ≈ 200 mV, E3 ≈ 181 mV (E3* ≈ −183 mV) and E4 ≈ 167 mV (E4* ≈ −170 mV) in positive (negative) Vb. As displayed in E1, E2 and E2* are higher than the highest phonon energy of our systems , suggesting that these overtone modes could be due to multi-phonon scattering events. Interestingly, we are able to find the combinations of two-phonon modes, comparable to each of the baseline excitation: E1 with P3 + P10 (≈215 mV), E2 (E2*) with P3 + P9 (≈204 mV), E3 (E3*) with P3 + P8 (≈183 mV), and E4 (E4*) with P3 + P7 (≈174 mV) sharing P3, out-of-plane acoustic K6 phonons of h-BN as a common excitation.We now discuss charge-density-dependent IETS spectra. As indicated with dotted-yellow boxes in h-BN heterostructures with a thin h-BN layer as a tunneling insulator and observed all the available phonon modes of h-BN at the ΓandK high symmetry points by electrical transport measurements for the first time. We find out out-of-plane motions of graphene and h-BN lattices become hardened when graphene/h-BN heterostructure is formed. Additionally, we observe charge-density-dependent excitations, which could be related to both multi-phonon and plasmon-related scattering processes. With IETS employing h-BN as a tunneling insulator, we have demonstrated that h-BN-based tunneling devices become a powerful experimental playground for exploring not only novel electronic structure2830h-BN hybrid devices as well as other low-dimensional materials such as TMDCs and carbon nanotubes. Moreover, benefited by much-improved-stable tunneling junctions, our tunneling devices make it possible to probe electronic and mechanical properties of nanoscale devices with applications of external variants such as magnetic fields, electro-magnetic waves, temperature, and pressure where previous tunneling experiments have been limited.In summary, we have performed inelastic electron tunneling spectroscopy studies of graphene/h-BN tunneling devices are fabricated using multiple steps of dry-transfer method developed by Dean et al.h-BN (>20 nm) are mechanically exfoliated from high-quality single crystals and transferred on thermally grown 300 nm thick SiO2 on Si. Next, single-layer graphene, thin h-BN (3 or 4 layers) and graphite flakes are sequentially transferred on top of bottom h-BN insulator. For each step, we first prepare Si substrates spin coated with water-soluble Poly-StyrenSulfonic (PSS) acid and PMMA. Desirable flakes mechanically exfoliated on the polymer-stacked Si substrates are examined under an optical microscope and later transferred to pre-defined locations with micro-manipulating transfer stage. Before dissolving PMMA in acetone, we bake out the samples at 200 °C for 2 minutes to promote the adhesion between transferred layers. It is critically important to have clean and flat interfaces for high-quality tunneling devices. To further remove any polymer residues and reduce the number of bubbles formed in 2-D heterostructures, we anneal the samples in the mixture of Ar and H2 (9:1 ratio by flow rate) at the elevated temperature 350 °C for more than 4 hours. In total, we applied dry-transfer method three times and high-temperature annealing four times before loading the samples in the cryostat for measurements. Additional annealing process is performed after fabricating Ti/Au (5 nm/55 nm) electrodes with electron beam lithography.Graphene/h-BN, graphite/graphene and graphene/h-BN heterostructures are calculated using density functional perturbation theory (DFPT)43h-BN are aGR = 0.245 nm and ah-BN = 0.251 nm, respectively, which are close to the experimentally observed values within 1%1h-BN heterostructure, we use the 6 × 6 × 2 supercell, assuming that single-layer graphene is commensurately aligned on top of h-BN layer in an AA-stacking direction. With obtained Grüneisen parameters for free-standing graphene (γGR) and h-BN (γh-BN) layer, we calculate the phonon modes of the unstrained graphene/h-BN heterostructure, as shown in h-BN/graphene heterostructure (aGR = 0.245 nm), the phonon modes of h-BN are increased by <γh-BN > = 1.13% in average compared with the unstrained graphene/h-BN heterostructure. Additionally, for the tensile-strained-graphene/h-BN heterostructure (aBN = 0.251 nm), the phonon modes of graphene is decreased by <γGR> = 1.43% in average, with respect to the unstrained graphene/h-BN heterostructure. Although AB-stacked graphene/h-BN heterostructure is expected to be more stable than its counterpart AA-stacked heterostructureh-BN heterostructures are fabricated using dry-transfer methodh-BN lattices, resulting in the atomic-stacking sequence is arbitrary.Phonon dispersions of How to cite this article: Jung, S. et al. Vibrational Properties of h-BN and h-BN-Graphene Heterostructures Probed by Inelastic Electron Tunneling Spectroscopy. Sci. Rep. 5, 16642; doi: 10.1038/srep16642 (2015).


The first reversible specific capacity of the hollow graphene spheres was as high as 903 mAh g-1 at a current density of 50 mAh g-1. Even at a high current density of 500 mAh g-1, the reversible specific capacity remained at 502 mAh g-1. After 60 cycles, the reversible capacity was still kept at 652 mAh g-1 at the current density of 50 mAh g-1. These results indicate that the prepared hollow graphene spheres possess excellent electrochemical performances for lithium storage. The high rate performance of hollow graphene spheres thanks to the hollow structure, thin and porous shells consisting of graphene sheets.The hollow graphene oxide spheres have been successfully fabricated from graphene oxide nanosheets utilizing a water-in-oil emulsion technique, which were prepared from natural flake graphite by oxidation and ultrasonic treatment. The hollow graphene oxide spheres were reduced to hollow graphene spheres at 500°C for 3 h under an atmosphere of Ar(95%)/H81.05.ue; 61.48.Gh; 72.80.Vp It is regarded as the ‘thinnest material in the universe’ with tremendous application potential. These attractive properties of graphene generate huge interest from different scientific communities in the possible implementation of graphene in different application fields such as biomedicine, reinforced composites, sensors, catalysis, energy conversion and storage device, electronics, and transparent electrodes for displays and solar cells [Since the paper on freestanding graphene was published by Novoselov et al. , the prear cells .4C6 stoichiometry) by density of states calculations [Nowadays, lithium-ion batteries are widely used in various electronic devices, such as notebook computers, cellular phones, camcorders, electric vehicles, and electric tools due to their superior properties such as long cycle life, high energy density, no memory effect, and environmental friendliness. To meet the increasing demand for lithium-ion batteries with high reversible capacity and energy density, much effort has been made to develop new electrode materials or design novel structures of electrode materials -14. Receulations .In this work, the hollow graphene oxide spheres (HGOSs) were fabricated directly from graphene oxide (GO) utilizing a water-in-oil emulsion technique, which were prepared from natural flake graphite by oxidation and ultrasonic treatment. The hollow graphene oxide spheres were reduced to hollow graphene spheres (HGSs) by heat treatment under a hydrogen atmosphere. Compared with the graphene sheets , the pre4 was employed as the oxidant to obtain graphite oxide. Firstly, 1 g of flake natural graphite powder with the mean diameter of 15 μm  was added to 23 mL of cooled (0°C) concentrated H2SO4. Then, 3 g of KMnO4 was added gradually with stirring and cooling, so that the temperature of the mixture was maintained below 10°C. The mixture was then stirred at 35°C for 30 min. After this, 46 mL of distilled water was slowly added to cause an increase in temperature to 98°C, and the mixture was maintained at that temperature for 15 min. The reaction was terminated by adding 140 mL of distilled water followed by 10 ml of 30% H2O2 solution. The suspension was then repeatedly centrifuged and washed twice with 5% HCl solution and then repeatedly with water until sulfate could not be tested with barium chloride. The collected precipitate was dispersed in 450 mL water and sonicated for 2 h. Then, the suspension was separated into the supernatant liquor and a golden colored residue by centrifugation at 5,000 rpm for 10 min. The supernatant was centrifuged again at 15,000 rpm for 5 min to remove the suspended substance. The precipitate was ultrasonicated, collected, and dried in a vacuum oven at 60°C; thus, GO nanosheets were obtained.GO nanosheets were prepared in two steps: the oxidation of flake natural graphite powder via a modified Hummers' method and ultrasonication. KMnO2(5%).GO nanosheets of 0.1 g were dispersed into aqueous ammonia  through agitation and were stirred at 30°C for 1 h to obtain the GO nanosheet suspension. Then, the suspension was slowly poured into hot olive oil  preheated to 90°C and intensely stirred for 30 min at 90°C. Subsequently, with the formation of a water-in-oil emulsion, the viscosity of the emulsion rapidly increased with the appearance of a golden foam. Half an hour later, when the bath temperature was increased to 95°C, the viscosity decreased gradually. With the intensive stirring, water was gradually separated from the oil. In the meantime, emulsion turned clear as olive oil. Finally, the emulsion system was cooled to room temperature. The HGOSs were obtained by centrifugation, washing, and drying. The HGOSs were reduced to HGSs at 500°C for 3 h under an atmosphere of Ar(95%)/Hλ = 1.5406 Å) over the range of 5 to 90° (2θ) at room temperature. The morphologies of the samples were observed by scanning electron microscope . The information of functional groups was measured by Fourier transform infrared spectroscopy instrument .The products were characterized by X-ray diffraction (XRD) on a Rigaku D/max-2500B2+/PCX system  using Cu/K radiation  mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) from Merck & Co., Inc.  was used as electrolyte. The Celgard 2400 microporous polypropylene film provided by Jimitek Electronic  Co. Ltd was used as separator. The coin-type cells were galvanostatically discharged (Li insertion) and charged (Li extraction) in the voltage range from 0.01 to 3.50 V vs. Li/Li+ at the different current densities. Electrochemical impedance spectroscopy measurements of the electrodes were carried out on an electrochemical workstation  using the frequency response analysis. The impedance spectra were obtained by applying a sine wave with amplitude of 5.0 mV over the frequency range from 100 kHz to 0.01 Hz.The electrochemical performances of the HGSs as anode materials for lithium-ion batteries were measured with the coin-type cells. The lithium sheets were used as both reference and counter electrodes, and composite electrodes comprising active mass , carbonaceous additive , and poly(vinylidene difluoride)  binder were used as working electrodes. The thickness and density of electrode are 50 μm and 1.95 mg cmThe morphology and structure of HGOSs and HGSs were characterized by SEM, and their images are shown in Figure d-spacing of GO increased to 0.765 nm from 0.335 nm of graphite, which is ascribed to the oxide-induced O-containing functional groups and inserted H2O molecules [-1 can be attributed to O-H stretching vibrations of adsorbed water molecules and structural OH groups, and the peak at 1,619 cm-1 can be attributed to O-H bending vibrations. The presence of carboxyl and epoxy functional groups can also be detected at around 1,724 and 1,224 and 1,053 cm-1, respectively [4 in the concentrated sulfuric acid, the original extended conjugated π-orbital system of graphite were destroyed, and oxygen-containing functional groups were inserted into carbon skeleton. Therefore, it is reasonable to believe that GO nanosheets should be regarded as ‘amphiphilic molecules’ and perform a surfactant-like function in a water/oil emulsion system [The structural changes from GO to HGSs were investigated by XRD measurement, and the patterns are shown in Figure olecules ,22 that ectively ,22. Thesn system . Due to 2, these functional groups derived from the intensive oxidation were eliminated, which can be proved by the disappearance of the peaks at 1,724, 1,619, 1,224, and 1,053 cm-1 while an appearance of a new peak at 1,631 cm-1  film formation and the generation of irreversible capacity. From the second cycle, the charge/discharge curve of HGS slope without distinguishable plateaus, which can be attributed to the smaller crystallite structure, high specific surface area [-1, respectively. Obviously, the reversible capacity of HGSs is much higher than that of previously reported graphene nanosheets (672 mA h g-1 at a current density of 0.2 mA cm-2) [-1 in the second cycle, but it was still maintained at 741 mA h g-1 in the fifth cycle. This evidence indicates that the prepared HGSs exhibited stable cyclic performance from the second cycle because of the formed stable SEI film during the first discharge process. The cyclic voltammograms (CV) of the prepared HGSs are shown in Figure Figure ace area , and disace area ,16. For mA cm-2) . The posmA cm-2) . The posmA cm-2) . It is wmA cm-2) , and themA cm-2) ,24-28. TmA cm-2) . The rev-1, 100 mA g-1, 200 m mA g-1, 500 m mA g-1, and 1,000 mA g-1 are shown in Figure -1 for HGSs. These results demonstrated that the prepared HGSs have an intensive potential as a candidate of anode materials with high reversible capacity, good cycle performance, and high rate discharge/charge capability.Cycle performance of HGSs at different current densities of 50 mA gTo investigate the kinetics of electrode process of HGS electrode, its Nyquist complex plane impedance plots are presented in Figure -1 at a current density of 50 mAh g-1. After 60 cycles at different current densities of 50 mA g-1, 100 mA g-1, 200 m mA g-1, 500 m mA g-1, and 1,000 mA g-1, the reversible specific capacity was still maintained at 652 mA g-1 at the current density of 50 mA g-1, which indicated that the prepared HGSs possess a good cycle performance for the lithium storage. The high rate performance of HGSs thanks to the hollow structure, thin and porous shells consisting of graphene sheets.The HGSs have been successfully fabricated from GO nanosheets utilizing a water-in-oil emulsion technique and thermal treatment. The electrochemical performance testing showed that the first reversible specific capacity of the HGSs was as high as high as 903 mAh gHGOSs: hollow graphene oxide spheres; GO: graphene oxide; HGSs: hollow graphene spheres; XRD: X-ray diffraction; SEM: scanning electron microscope; FTIR: Fourier transform infrared; SEI: solid electrolyte interface; CV: cyclic voltammograms.The authors declare that they have no competing interests.RRY designed parts of the experiments and sample preparations and drafted the manuscript. DLZ is the corresponding author and provided a great help for experimental designs. LZB, NNY, and LX took part in sample preparation and characterizations and discussed the results. All authors have read and approved the final manuscript.


Hypoxia effects on pulmonary artery structure and function are key to diseases such as pulmonary hypertension. Recent studies suggest that growth factors called neurotrophins, particularly brain-derived neurotrophic factor (BDNF), can influence lung structure and function, and their role in the pulmonary artery warrants further investigation. In this study, we examined the effect of hypoxia on BDNF in humans, and the influence of hypoxia-enhanced BDNF expression and signaling in human pulmonary artery smooth muscle cells (PASMCs).2+ responses to serotonin: an effect altered by HIF1α inhibition or by neutralization of extracellular BDNF via chimeric TrkB-Fc. Enhanced BDNF/TrkB signaling increased PASMC survival and proliferation, and decreased apoptosis following hypoxia.48h of 1% hypoxia enhanced BDNF and TrkB expression, as well as release of BDNF. In arteries of patients with pulmonary hypertension, BDNF expression and release was higher at baseline. In isolated PASMCs, hypoxia-induced BDNF increased intracellular CaEnhanced expression and signaling of the BDNF-TrkB system in PASMCs is a potential mechanism by which hypoxia can promote changes in pulmonary artery structure and function. Accordingly, the BDNF-TrkB system could be a key player in the pathogenesis of hypoxia-induced pulmonary vascular diseases, and thus a potential target for therapy. Samples were from lobectomies or pneumonectomies for focal non-infectious indications such as localized tumors, and were classified as being non-PH or PH based on clinical data. The limited PH data set was entirely mild-moderate, where mean PAP clinically estimated by transthoracic or transesophageal echocardiography ranged from 25 mmHg (mild) to 48 mmHg (moderate), given high anesthesia risk for non-transplant surgeries in severe PH. Samples were limited to areas distant from the focal pathologies as identified by the pathologist and verified under gross microscopy. Since the samples and clinical data were de-identified, the protocol was considered minimal risk Human Subjects Research.2 after which the source tissue was removed and cells plated in 60mm dishes , 8 well Labtek culture chambers or 96 well plates (imaging and proliferation assays). Prior to experimentation, cells were serum-deprived for 24h, and all cells were used between passages 1 and 4 to ensure maintenance of PASMC phenotype, verified by markers such as smooth muscle actin and myosin, and transgelin (SM22), but absence of fibroblast specific protein.Samples were transported rapidly in ice-cold Hank’s Balanced Salt Solution (HBSS). The PA segment was partitioned for testing of endothelium-intact PA, and for analysis of endothelium- and adventitia-denuded PA smooth muscle. The latter was used as tissue or for isolation of PASMCs, which involved mincing and growth of explants in DMEM with 10% FBS/1% ABAM. Tissue explants were maintained for 5–7 days at 37°C in 95% air/5% CO2 for 48h in a hypoxia chamber (Biospherix C-chamber). The chamber was flushed 3 times for 10 min each with high flow 1% O2 prior to use. For BDNF exposure, intact PA or isolated PASMCs were incubated for 24 or 48 h (see protocols) at 37°C in regular growth media (vehicle control) or 100 pM recombinant human BDNF . This concentration was based on previous reports of circulating serum BDNF levels of ~20 ng/ml which translates to <1 nM. ; i.[in situ by exposing PASMCs to known Ca2+ levels with the ionophore A-23187.We have previously published techniques for imaging of cellular [Ca2+]i. Briefly,Proliferation of PASMCs was assayed at 48h (with or without preceding interventions) using the fluorescent CyQuant NF kit (Invitrogen) as previously described. Cells wepost hoc analysis using SigmaPlot , and statistical significance was established at P < 0.05. Values are means ± SE.PA tissue or PASMC experiments were performed in samples from 3–7 patients (no pooling), with 3 repeats/sample. Data were analyzed and results were compared using one way ANOVA with Student-Newman-Keuls or Dunnet’s 2 which is known to induce HIF1α; see below)i responses to 1 μM serotonin  but not eliminated. Furthermore, [Ca2+]i responses to 5HT were diminished in the presence of the HIF1α inhibitor  enhanced the amplitude of i in PASMCs in the presence of hypoxia would suggest an opposing, vasoconstrictive effect that may offset any beneficial effects of BDNF on endothelium. Furthermore, the enhancing effect of BDNF on smooth muscle proliferation demonstrated in these data and reported by others [2+]i regulation, BDNF can activate mechanisms such as IP3 and influx pathways such as TRPCs, both of which are well-known to be important in PASMCs  hig hig22] hy others  would onn PASMCs ,57,58,592+]i responses to serotonin, including enhancement of Ca2+ influx as well as enhanced SR Ca2+ release. Furthermore, the enhancing effect of BDNF on agonist responses is probably not specific only to serotonin. For example, we have previously demonstrated in human airway smooth cells that BDNF can increase baseline [Ca2+]i and responses to agonists such as Ach. [2+]i regulatory proteins such as CD38, Orai1, IP3 and RyR receptors. i by altering expression of regulatory proteins: a topic yet to be examined.There are likely a number of mechanisms to explain how BDNF increases i and proliferation that can potentially contribute to hypoxia effects on arterial contractility and remodeling. While locally produced BDNF may be particularly important, the potential exists for circulating BDNF to further influence PA. Future studies should examine the mechanisms by which hypoxia can modulate endothelial vs. PASMC BDNF/TrkB signaling and the overall, in vivo effect on PA contractility and remodeling, especially in the context of diseases such as PH.In conclusion, our study demonstrates enhancement of BDNF and TrkB expression and signaling in PASMCs following hypoxia, resulting in increased PASMC [Ca


Maize streak Reunion virus (MSRV) is a member of the Mastrevirus genus in the family Geminiviridae. Of the diverse and increasing number of mastrevirus species found so far, only Wheat dwarf virus and Sweetpotato symptomless virus 1 have been discovered in China. Recently, a novel, unbiased approach based on deep sequencing of small interfering RNAs followed by de novo assembly of siRNA, has greatly offered opportunities for plant virus identification.Samples collected from maize leaves was deep sequencing for virus identification. Subsequently, the assay of PCR, rolling circle amplification and Southern blot were used to confirm the presence of a mastrevirus.Maize streak Reunion virus Yunnan isolate  was identified from maize collected from Yunnan Province, China, by small RNA deep sequencing. The complete genome of this virus was ascertained as 2,880 nucleotides long by conventional sequencing. A phylogenetic analysis showed it shared 96.3 % nucleotide sequence identity with the isolate of Maize streak Reunion virus from La Reunion Island. To our knowledge, this is the first identification of MSRV in China. Analyses of the viral derived small interfering RNAs (vsiRNAs) profile showed that the most abundant MSRV-YN vsiRNAs were 21, 22 and 24 nt long and biased for A and G at their 5’ terminal residue. There was a slightly higher representation of MSRV-YN siRNAs derived from the virion-sense strand genome than the complementary-sense strand genome. Moreover, MSRV-YN vsiRNAs were not uniformly distributed along the genome, and hotspots were detected in the movement protein and coat protein-coding region.A mastrevirus MSRV-YN collected in Yunnan Province, China, was identified by small RNA deep sequencing. This vsiRNAs profile derived from MSRV-YN was characterized, which might contribute to get an insight into the host RNA silencing defense induced by MSRV-YN, and provide guidelines on designing antiviral strategies using RNAi against MSRV-YN.The online version of this article (doi:10.1186/s12985-015-0384-3) contains supplementary material, which is available to authorized users. Geminiviridae are taxonomically classified into seven genera  based on insect vector, host range and genome organization , which was abbreviated to MSRV-YN.In a PCR using primer pair F/R1 to investigate the incidence of MSRV-YN among the 22 maize samples collected from Yuanmou county, Yunnan province, amplicons of the expected size, about 700 bp, were generated in ten of the 22 tested samples, revealing an infection rate for isolate MSRV-YN of 45.5 % (data not shown). To our knowledge, this is the first report of a isolate of MSRV in China.Back-to-back primers F/R designed based on the assembled contigs were used to amplify the full-length genomic sequences of MSRV-YN from a crude extract of total DNA from the maize sample, yielding a fragment of about 3.0 kb. This fragment was then cloned and sequenced by conventional Sanger sequencing and assembled by SeqMan , generating a complete sequence 2880 bp long (GenBank: KT717933). A BLASTn search using the completed genome of MSRV-YN in NCBI revealed significant similarity (98 %) to the isolate of MSRV from La Reunion Island (GenBank: JQ624880).To further prove the presence of MSRV-YN, the aforementioned DNA was used as template for RCA amplification followed by restriction fragment length polymorphism (RFLP) analyses, which is a nonsequence-specific method that potentially allows the identification of all circular DNA viruses. Three different RCA-amplified products from randomly selected MSRV-YN positive samples were digested with the BamHI restriction endonuclease, which proved to have a single restriction site based on the information of the obtained complete genome sequence of MSRV-YN. As expected, a single DNA fragment of about 3.0 kb was obtained, the size expected for a mastrevirus. Meanwhile, no band was ever found in the negative control from healthy maize leaves Fig. . Next, SMastrevirus, revealed that MSRV-YN shares <63 % genome-wide pairwise identity with known Mastrevirus species, except that for a close identity with MSRV (GenBank: KJ437669); complete genome identity and amino acid identities for MP, CP, Rep, RepA are 96.3, 99.0, 98.0, 95.1 and 93.3 %, respectively  in Nicotiana benthamiana [Cabbage leaf curl virus (CabLCV) in Arabidopsis thaliana [The identification of viral small interfering RNAs (vsiRNAs) mapping to specific viral genome provides strong evidence for presence of the virus. We characterized the profile of vsiRNAs derived from MSRV-YN Fig. . A totalthamiana  and Cabbthaliana .Fig. 4ChA. thaliana, AGO2 and AGO4 predominantly favored small RNAs starting with the 5’ -terminal A, AGO1 preferentially recruited sRNAs initiating with a 5’ -terminal U, while AGO5 predominantly bound small RNAs that with a 5’ -terminal C [Previous studies have indicated that the recruiting of sRNAs into specific AGO complexes mainly depends on the identity of the first 5’ -nucleotide of sRNAs , 17. To rminal C , 17. It rminal C , 15, 18.rminal C , 18, 19.When the vsiRNAs strand polarity was evaluated using the 20–25 nt vsiRNAs, a slightly higher representation of MSRV-YN siRNAs derived from the virion-sense strand (positive vsiRNAs) was unexpectedly observed, accounting for about 63.46 % of the total vsiRNAs, irrespective of length Fig. , suggestCucumber mosaic virus satellite RNA could be targeted more efficiently by DCL4 [A genome-wide view of vsiRNAs revealed that the vsiRNAs of MSRV-YN were not uniformly distributed along each genome segment, with the most abundant siRNAs matched both positive and negative strands of the MP and CP-coding region Fig. , indicat by DCL4 . Since M by DCL4 . A greatSetaria barbata and Rottboellia sp. in Nigeria, suggesting expanded host and geographical ranges for this virus [Currently, mastreviruses are receiving more and more attention since they have been associated with many serious crop diseases. Of the 29 currently recognized mastrevirus species, 23 include viruses that can infect monocotyledonous hosts and 6 include viruses that infect dicotyledonous hosts . To dateis virus . This fiRecent advances in deep sequencing have greatly accelerated the accuracy and rate of virus discovery. Our study, the first to use deep sequencing to characterize siRNAs derived from MSRV-YN, should provide guidelines on designing antiviral strategies using RNAi against MSRV-YN.Zea mays) leaf samples were collected from five maize fields in Yuanmou County, Yunnan Province, China, the distance between which ranged from 100 m to 2000 m more than. These samples displaying a range of disease symptoms such as yellowing and chlorotic streaks along leaf veins (data not shown) were stored at −80 °C. Total RNA was extracted from 0.1 g of symptomatic maize leaf according to the manufacturer’s instructions . The purified RNA preparations were evaluated using a spectrophotometer  and agarose gel electrophoresis. The better quality RNA described as YM was shipped with dry ice to the Beijing Genomics Institute (BGI) for small RNA library construction and sequencing.In May 2014, 22 maize (k-mer) required for joining two sRNAs into a contig [Sequencing was performed according to the manufacturers’ protocol by using the high-throughput Illumina HiSeq-2000 sequencing technology. Data processing was conducted using a custom bioinformatics pipeline. Raw data were analyzed using an in-house Perl script, and 18–28 nt reads consisting of trimmed sRNA sequences were collected for subsequent analysis. The Velvet program  was useda contig . The assa contig .A CTAB-based extraction method  was usedThe rolling circle amplification of circular DNA was conducted using TempliPh 500 Amplification Kit  according to the manufacturer’s protocol. From 10 to 100 ng of total deoxyribonucleic acids was dissolved in 5 μl sample buffer, denatured at 95 °C for 3 min and then immediately cooled down on ice for 10 min. Subsequently, 5 μl reaction buffer and 0.1 μl enzyme mix were added, and the reaction was run at 30 °C for 18 h. The reaction was then stopped at 65 °C for 5 min. The RCA products were digested with the single restriction enzyme BamHI, and fragments were then separated on 1 % agarose gels, excised and recovered using a Gel Extraction Kit (Axygen Scientific Inc). For Southern blot analysis, 20 μg of total DNA preparations and 20 ng RCA recovered products were used and hybridized with a virus-specific probe according to standard Southern blot protocols. The probe was synthesized using the primer pair F1/R1  were predicted using the ORF finder function of the Snap Gene software . NucleotSmall RNA mapping was conducted by Bowtie 1.0 with zero mismatch, and results were exported to Microsoft Excel for further analysis. The program MISIS  was used