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The Dextroamphetamine Transdermal System (d-ATS) was developed as an alternative to oral amphetamine (AMP) formulations for ADHD. In a pivotal study, d-ATS met primary and secondary efficacy endpoints for ADHD in children and adolescents. Study subjects wore d-ATS for 9 hours, and an improvement in Swanson, Kotkin, Agler, M-Flynn, and Pelham scale (SKAMP) total score was observed from 2 through 12 hours after application. Patients with ADHD may need varying durations of treatment for symptoms from day to day. This analysis describes the exposure-response (E-R) relationship for d-ATS and explores possible outcomes for wear times ≤9 hours under varying assumptions.
Methods
A population pharmacokinetic (PK) model was developed to describe AMP disposition following d-ATS administration. This model was used to construct a population pharmacokinetic/pharmacodynamic (PK/PD) model from SKAMP total score data from two pediatric clinical studies to characterize onset and duration of effect after d-ATS administration. The integrated PK/PD model was used to describe the d-ATS E-R relationship and simulate the potential onset and duration of effect of d-ATS in response to various removal times (when <9 hours) by utilizing SKAMP scores as the efficacy measure. Subject-level AMP PK and SKAMP profiles were simulated for d-ATS removal at 4–9 hours post-application under different assumptions for AMP absorption after early patch removal. Modifications were made to the original population PK model to simulate patch removal.
Results
Data from 81 children and 41 adolescents, 6–17 years old, were included. The model provided a reasonable description of the SKAMP score over time, showing an initial decline ~2 hours after patch application. In approximately 50% of children and adolescents, the maximum decline in SKAMP scores was observed within the first 4 hours after patch application. Earlier simulated d-ATS removal times were associated with reduced systemic exposure and earlier return to near-baseline scores across the range of assumptions tested.
Under different assumptions, the graphs changed modestly but not dramatically. For example, with moderate/conservative assumptions, following a 9-hour wear time, SKAMP scores returned to within 90% of baseline value in ~49% of subjects by 12 hours and ~80% of subjects by 16 hours. Following a 4-hour wear time, percentages were ~74% by 12 hours and ~95% by 16 hours.
Conclusions
Simulation results suggest that the duration of d-ATS efficacy may be related to wear time, which can be adjusted according to treatment needs, consistent with published observations for another transdermal stimulant. The d-ATS patch provides the ability to control medication exposure by shortening wear time, allowing treatment duration to be individualized and optimized in ADHD patients who have varying schedules and needs.
Patients with hearing loss and tinnitus face lengthy waits to be seen in the ENT clinic. SHOEBOX Audiometry is an iPad-based, audiometric screening tool. A virtual hearing loss and non-pulsatile tinnitus clinic involving an ENT specialist virtually assessing cases based on the SHOEBOX audiogram, a patient symptom questionnaire and the primary care referral letter were implemented. This service evaluation explored the outcomes of the virtual clinic in reducing the need for a face-to-face ENT appointment.
Method
This was a retrospective service evaluation of the first six months of the virtual hearing loss and non-pulsatile tinnitus clinic.
Results
A total of 210 patients were included: 34.8 per cent (73) were discharged without requiring audiologist assessment or an ENT appointment, 51.9 per cent (109) required formal audiological assessment, 36.7 per cent (77) required imaging and only 13.8 per cent (29) required a face-to-face ENT appointment.
Conclusion
A virtual hearing loss and non-pulsatile tinnitus clinic minimised the number of patients requiring a traditional face-to-face clinic appointment within ENT.
The deficiency of polyunsaturated fatty acids (PUFAs) and an alteration between the ratio of omega-6 and omega-3 PUFAs may contribute to the pathogenesis of depressive disorders.
Objectives
To investigate the levels of omega-3 and omega-6 in red cell membranes (mPUFAs) and plasma (pPUFAs) of patients with treatment-resistant (TRD) and non-treatment resistant depression (non-TRD).
Methods
TRD and non-TRD consisted of 75 patients enrolled at the Psychiatric and Clinic Psychology Unit of the University of Rome Tor Vergata, Rome, Italy, and met the DSM-IV criteria for major depressive disorder (MDD). A group of healthy controls (HC) matched for agender and age was enrolled. All blood samples were performed in conditions of an empty stomach between 07:00 am and 09:00 am. For each subject were obtained 5 ml of whole blood with the use of tubes for plasma with EDTA as an anticoagulant. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for omega-3 and arachidonic acid (AA) for omega-6 were measured.
Results
Levels of pPUFAs did not differ between the three groups. The mPUFAs were altered in the MDD. TRD and non-TRD had lower EPA and AA values respect to the HC. DHA in red cell membranes was lower in TRD than non-TRD and HC.
Conclusions
Changes in levels of PUFAs in red cell membranes, but not in plasma, may be an important factor to evaluate the resistance to the pharmacological treatment.
We present an overview of the Middle Ages Galaxy Properties with Integral Field Spectroscopy (MAGPI) survey, a Large Program on the European Southern Observatory Very Large Telescope. MAGPI is designed to study the physical drivers of galaxy transformation at a lookback time of 3–4 Gyr, during which the dynamical, morphological, and chemical properties of galaxies are predicted to evolve significantly. The survey uses new medium-deep adaptive optics aided Multi-Unit Spectroscopic Explorer (MUSE) observations of fields selected from the Galaxy and Mass Assembly (GAMA) survey, providing a wealth of publicly available ancillary multi-wavelength data. With these data, MAGPI will map the kinematic and chemical properties of stars and ionised gas for a sample of 60 massive (${>}7 \times 10^{10} {\mathrm{M}}_\odot$) central galaxies at $0.25 < z <0.35$ in a representative range of environments (isolated, groups and clusters). The spatial resolution delivered by MUSE with Ground Layer Adaptive Optics ($0.6-0.8$ arcsec FWHM) will facilitate a direct comparison with Integral Field Spectroscopy surveys of the nearby Universe, such as SAMI and MaNGA, and at higher redshifts using adaptive optics, for example, SINS. In addition to the primary (central) galaxy sample, MAGPI will deliver resolved and unresolved spectra for as many as 150 satellite galaxies at $0.25 < z <0.35$, as well as hundreds of emission-line sources at $z < 6$. This paper outlines the science goals, survey design, and observing strategy of MAGPI. We also present a first look at the MAGPI data, and the theoretical framework to which MAGPI data will be compared using the current generation of cosmological hydrodynamical simulations including EAGLE, Magneticum, HORIZON-AGN, and Illustris-TNG. Our results show that cosmological hydrodynamical simulations make discrepant predictions in the spatially resolved properties of galaxies at $z\approx 0.3$. MAGPI observations will place new constraints and allow for tangible improvements in galaxy formation theory.
The cortical metabolic patterns of 12 schizophrenics experiencing hallucinations and/or pseudo-hallucinations were investigated using positron tomography and 18F-fluoro-deoxy-glucose. Andreasen's scales were scored and the patients (all “mixed“) were classified in a “positive” or a “negative” group and compared to a group of 6 normal controls. The data were analyzed across groups for absolute metabolic rates, metabolic indices (cortical region/whole studied cortex), and specific indices exploring the sensory non-association/posterior parietal association and the prefrontal association/posterior parietal association dimensions. Whole-cortex metabolic rate in the negative group was found to be lower than both the control (P=0.02) and the positive group (P = 0.002) while the positive group did not differ significantly from the controls. We found “hypofrontality” to be without difference between the positive and the negative group (controls: 7±0.7, positive: 5.9±0.2, negative: 4.9±0.15, mean±SEM in mg/min/100 g). However, the prefrontal association/posterior parietal association ratio was increased in the negative group (P=0.02). A major finding was an increase in the posterior non-association/posterior parietal association ratio in the whole schizophrenic group as compared to the controls (P = 0.004), this being more marked in the negative (P=0.01) than in the positive group. Arguments are given to support the hypothesis that this particular increase could be related to the hallucinatory activity of the patients.
Previous studies reported that music therapy (MT) exerts a positive effect on many medical and neuropsychiatric disorders. The use of MT has been proposed also for patients with severe mental illnesse (SMI), altrough further studies are still needed. The aim of the present study was to evaluate the effects on a structured MT program on clinical and social functioning indices of patient with SMI, hospitalized in an psychiatric emergency ward.
The MT intervention followed the Benenzon model of MT and was delivered biweekly to 61 patients consecutively admittted to the psychiatric emergency ward. Subjects who did not complete the two-week MT intervention (N=45) were considered as the control group. all subjects were administred the Brief Psychiatric Rating Scale (BPRS) to evaluate the general psychopatology, the Hospital Anxiety And Depression Scale (HADS) for affective symptomatology, the Clinical Global Impression Scale (CGI-S) for severity of symptoms and the Global Assestment of Functioning (GAF) for psychosocial functioning.
A repeated measures analysis of variance revealed that patients who unerwent the MT intervention had a statistically significant reduction of general and affective psychopatology scores and of symptoms severity with respect to the control group, after observation period.
Our result are in line with previous studies confirming that MT may exert positive effects on psychopatology (in particular, on affective symptomatology) of patient with SMI, and extend this observation to an emergency setting, with short period of hospital stay.
QTc interval prolongation is considered a risk factor for fatal polymorphic ventricular tachycardia, which can result in sudden cardiac death. Most psychotropic drugs have a dose-dependent potential to prolong the QTc interval. However, other factors require appropriate consideration, including: age; gender; other medications; electrolyte abnormalities; severe comorbid conditions, such as co-occurring alcohol or substances abuse/dependence.
Objectives
The objective was to study the potential mediating roles of alcohol/substances abuse on QTc prolongation.
Aims
The Italian research group STAR Network, in collaboration with the Young Italian Psychiatrists Association, aimed to evaluate the frequency of QTc interval prolongation in a sample of patients under treatment with psychotropic drugs through a cross-sectional national survey.
Methods
A sample of 2411 unselected patients were enrolled after performing an ECG during the recruitment period. Sociodemographic and clinical characteristics were collected from medical records. Collected data underwent statistical analysis.
Results
A total of 11.2% of patients reported alcohol abuse, and only 8.9% psychotropic substances. According to the threshold, less than 20% of patients had a borderline value of QTc, and 1% a pathological value. Patients with co-occurring alcohol misuse and drug abuse were more likely to have longer QTc interval.
Conclusions
The present study describes the frequency of QTc prolongation in real-world clinical practice. Before prescribing a psychotropic drug, the physician should carefully assess its risks and benefits to avoid this type of adverse reaction, particularly when additional risk factors are present. The potential role of alcohol and substances on QTc length could be particularly useful in emergency settings.
Disclosure of interest
The authors have not supplied their declaration of competing interest.
A mixture of natural ingredients, namely, DHA, phosphatidylcholine, silymarin, choline, curcumin and d-α-tocopherol, was studied in subjects with non-alcoholic fatty liver disease (NAFLD). Primary endpoints were serum levels of hepatic enzymes, and other parameters of liver function, the metabolic syndrome and inflammation were the secondary endpoints. The coagulation–fibrinolysis balance was also thoroughly investigated, as NAFLD is associated with haemostatic alterations, which might contribute to increased cardiovascular risk of this condition. The present study involved a double-blind, randomised, multicentre controlled trial of two parallel groups. Subjects with NAFLD (18–80 years, either sex) received the active or control treatment for 3 months. All assays were performed on a total of 113 subjects before and at the end of supplementation. The hepatic enzymes aspartate aminotransferase (AST), alanine aminotransferase and γ-glutamyl transpeptidase decreased from 23·2 to 3·7 % after treatment, only the AST levels reaching statistical significance. However, no differences were found between control and active groups. Metabolic and inflammatory variables were unchanged, except for a slight (less than 10 %) increase in cholesterol and glucose levels after the active treatment. Coagulation–fibrinolytic parameters were unaffected by either treatment. In conclusion, chronic supplementation with the mixture of dietary compounds was well tolerated and apparently safe in NAFLD subjects. The trial failed to demonstrate any efficacy on relevant physiopathological markers, but its protocol and results may be useful to design future studies with natural compounds.
We use the LLAMA survey to study the density and outflow rate of ionized gas in a complete volume limited sample of local (<40 Mpc) luminous (43.0 < log LAGN(erg/s) < 44.5) AGN selected by very hard 14-195 keV X-rays. The detailed data available for this survey enable us to measure the density of the outflowing ionized gas in the central 300 pc of these AGN using three different and independent methods (the standard [SII] doublet ratio; a method comparing [OII] and [SII] ratios that include auroral and transauroral lines; and a recently proposed method based on the ionization parameter). For each method there is, as expected, a modest spread of densities among the AGN in the sample. But remarkably, the median densities for each method differ hugely, by an order of magnitude from below 400 cm-3 to almost 5000 cm-3. We discuss how the derived densities can be reconciled, and what the impact is on the implied outflow rate.
A combination of intimate partner violence (IPV) and depression is a common feature of the perinatal period globally. Understanding this association can provide indications of how IPV can be addressed or prevented during pregnancy. This paper aims to determine the prevalence and correlates of IPV among pregnant low-income women with depressive symptoms in Khayelitsha, South Africa, and changes in IPV reports during the course of the perinatal period.
Methods.
This study is a secondary analysis of data collected as part of a randomised controlled trial testing a psychosocial intervention for antenatal depression. IPV, socio-demographic measures, depression and other mental health measures were collected at recruitment (first antenatal visit), 8 months gestation, and 3 and 12 months postpartum. IPV was defined as a sexual or physical violence perpetrated by the participant's partner in the past 3 months. Descriptive statistics are reported.
Results.
Of 425 recruited depressed participants, 59 (13.9%) reported IPV at baseline, with physical IPV being the most frequently reported (69.5%). Reported IPV was associated with greater emotional distress, potentially higher food insecurity and higher rates of alcohol abuse. There were clear longitudinal trends in reported IPV with the majority of women no longer reporting IPV postpartum. However, some women reported IPV at later assessment points after not reporting IPV at baseline.
Conclusions.
There is a strong association between IPV and depression in pregnancy. IPV reports remit over time for the women in this study, although the reason for this reduction is not clear and requires further investigation.
The current study compared beef production, quality and fatty acid (FA) profiles of yearling steers fed a control diet containing 70 : 30 red clover silage (RCS) : barley-based concentrate, a diet containing 11% sunflower seed (SS) substituted for barley, and diets containing SS with15% or 30% wheat dried distillers’ grain with solubles (DDGS). Additions of DDGS were balanced by reductions in RCS and SS to maintain crude fat levels in diets. A total of two pens of eight animals were fed per diet for an average period of 208 days. Relative to the control diet, feeding the SS diet increased (P<0.05) average daily gain, final live weight and proportions of total n-6 FA, non-conjugated 18:2 biohydrogenation products (i.e. atypical dienes) with the first double bond at carbon 8 or 9 from the carboxyl end, conjugated linoleic acid isomers with the first double bond from carbon 7 to 10 from the carboxyl end, t-18:1 isomers, and reduced (P<0.05) the proportions of total n-3 FA, conjugated linolenic acids, branched-chain FA, odd-chain FA and 16:0. Feeding DDGS-15 and DDGS-30 diets v. the SS diet further increased (P<0.05) average daily gains, final live weight, carcass weight, hot dressing percentage, fat thickness, rib-eye muscle area, and improved instrumental and sensory panel meat tenderness. However, in general feeding DGGS-15 or DDGS-30 diets did not change FA proportions relative to feeding the SS diet. Overall, adding SS to a RCS-based diet enhanced muscle proportions of 18:2n-6 biohydrogenation products, and further substitutions of DDGS in the diet improved beef production, and quality while maintaining proportions of potentially functional bioactive FA including vaccenic and rumenic acids.
Mentalizing deficits are a hallmark of the autism spectrum condition (ASC) and a potential endophenotype for atypical social cognition in ASC. Differences in performance and neural activation on the ‘Reading the Mind in the Eyes’ task (the Eyes task) have been identified in individuals with ASC in previous studies.
Method.
Performance on the Eyes task along with the associated neural activation was examined in adolescents with ASC (n = 50), their unaffected siblings (n = 40) and typically developing controls (n = 40). Based on prior literature that males and females with ASC display different cognitive and associated neural characteristics, analyses were stratified by sex. Three strategies were applied to test for endophenotypes at the level of neural activation: (1) identifying and locating conjunctions of ASC–control and sibling–control differences; (2) examining whether the sibling group is comparable to the ASC or intermediate between the ASC and control groups; and (3) examining spatial overlaps between ASC–control and sibling–control differences across multiple thresholds.
Results.
Impaired behavioural performance on the Eyes task was observed in males with ASC compared to controls, but only at trend level in females; and no difference in performance was identified between sibling and same-sex control groups in both sexes. Neural activation showed a substantial endophenotype effect in the female groups but this was only modest in the male groups.
Conclusions.
Behavioural impairment on complex emotion recognition associated with mental state attribution is a phenotypic, rather than an endophenotypic, marker of ASC. However, the neural response during the Eyes task is a potential endophenotypic marker for ASC, particularly in females.
Axial heterostructure nanowires with Si and SiGe segments have been grown using Au metal seed as catalyst by chemical vapor deposition (CVD) via vapor-liquid-solid process (VLS). We report on the effect of growth intervention on the droplet stability which in turn modifies NW morphology and interfacial abruptness. Growth stop of 2 minutes on transition from one material to another have been demonstrated to suppress reservoir effect by Au catalyst. The two SiGe/Si and Si/SiGe heterointerfaces are found to be assymetric. The former being diffused while the latter one is sharp. Furthermore, geometric phase analysis reports elastic deformation at the heterointerface. Nanowire undergoes rotation in both clock and anticlockwise direction at their sidewalls with an angle of 2.5° in order to accommodate this strain.
Multi-slice computed tomography (MSCT) has proven inseveral studies to have a high diagnostic accuracy for the detectionor exclusion of coronary artery disease. A major concern with coronaryMSCT, however, is the associated radiation exposure of patients.Recent studies suggest that use of a 64-slice scanner is associatedwith a non-negligible lifetime attributable risk of cancer. Severalstrategies can be used to reduce patient exposure in coronary MSCT.The purpose of this multicenter study was to investigate the effectsof the adjustment of tube voltage and current on radiation doseand image interpretability. MSCT with retrospective ECG gating was performedin 315 patients. The dose-length product (DLP) in the patients enrolledwith the dose reduction protocol resulted in a 36% overall reductionin the mean radiation dose (911 ± 289 mGy.cm) compared with thestandard protocol (1427 ± 226 mGy.cm, p < 0.001).Nevertheless, image interpretability was maintained. This studyon coronary MSCT demonstrates that the radiation dose can be significantly reducedby parameter optimization, with maintained image interpretability.
The current study was conducted to determine the effect of different α-tocopherol (vitamin E) inclusion levels on trans(t)-18:1 and conjugated linoleic acid (CLA) profiles in subcutaneous and intramuscular fat of steers fed a barley-based diet. Fifty-six feedlot steers were offered a barley-based finisher diet (73% steam rolled barley, 22% barley silage and 5% supplement as-fed basis) with four levels of supplementary dl-α-tocopheryl acetate (340, 690, 1040 or 1740 IU/steer per day) for 120 days. Adding vitamin E to the diet had little effect on the overall fatty acid composition of intramuscular fat. The proportion of individual and total t,t- and cis(c),t-CLA, n-3 fatty acids, total polyunsaturated fatty acids (PUFA), mono-unsaturated fatty acids and saturated fatty acids to PUFA ratio in subcutaneous fat were not influenced (P > 0.05) by dietary vitamin E supplementation. Increasing levels of vitamin E led to linear reductions in t6-/t7-/t8-18:1 and t10-18:1 (P < 0.05), and linear increase in t11-/t10-18:1 ratio (P < 0.05) in subcutaneous fat. The content of 20:3n-6 and total n-6 in subcutaneous fat decreased (P < 0.05) linearly with increasing amounts of vitamin E. The subcutaneous fat n-6:n-3 ratio showed a quadratic (P < 0.05) response to vitamin E. In conclusion, although vitamin E supplementation has some potential to reduce t10-18:1 formation and increase t11-/t10-18:1 ratio in subcutaneous fat of cattle fed barley-based diets, the changes in the present study were limited and may not have been sufficient to impact on human health.
To evaluate meat quality of beef with different α-tocopherol tissue levels, 55 feedlot steers were fed a barley-based finisher diet with four vitamin E supplementation levels (0, 350, 700 and 1400 IU dl-α-tocopheryl acetate/animal per day) for 120 days. Although the increase in oxidation levels overtime was much smaller (P < 0.001) in the high-medium and high groups, α-tocopherol tissue levels did not affect (P > 0.05) pH, proximate analysis, drip and cooking losses, and shear force of steaks. No effect of α-tocopherol tissue levels was found in retail evaluation of steaks after a short ageing time of 6 days, but with 21 days of ageing, a delay in formation of metmyoglobin (P = 0.008) was observed in steaks with higher tissue levels of α-tocopherol. Similar results were found for ground beef (25% fat) prepared from 6-day aged meat. Thus, higher α-tocopherol tissue levels protect ground beef and long-aged steaks from discolouration and lipid oxidation.
Inflammatory bowel diseases (IBD) are immunomediated ailments affecting millions of individuals. Although diet is regarded as an important factor influencing IBD, there are no accepted dietary recommendations presently available. We administered 7·6 % lyophilised apples obtained from two cultivars (Golden Delicious and Marie Ménard, low and high in polyphenols, respectively) to HLA-B27 transgenic rats which develop spontaneous IBD. After 3 months feeding, rats fed Marie Ménard apples had reduced myeloperoxidase activity (3·6 (sem 0·3) v. 2·2 (sem 0·2) U/g tissue; P < 0·05) and reduced cyclo-oxygenase-2 (P < 0·05) and inducible NO synthase gene expression (P < 0·01) in the colon mucosa and significantly less diarrhoea (P < 0·05), compared with control rats. Cell proliferation in the colon mucosa was reduced significantly by feeding Golden Delicious apples, with a borderline effect of Marie Ménard apples. Gene expression profiling of the colon mucosa, analysed using the Whole Rat Genome 4 × 44 K Agilent Arrays, revealed a down-regulation of the pathways of PG synthesis, mitogen-activated protein kinase (MAPK) signalling and TNFα–NF-κB in Marie Ménard-fed rats. In the stools of the animals of this group we also measured a significant reduction of bacteria of the Bacteriodes fragilis group. In conclusion, the administration of Marie Ménard apples, rich in polyphenols and used at present only in the manufacturing of cider, ameliorates colon inflammation in transgenic rats developing spontaneous intestinal inflammation, suggesting the possible use of these and other apple varieties to control inflammation in IBD patients.
The structural evolution with temperature of some V2O5 gels and thin films is presented, and the role of the hydrolysis conditions is investigated. Several techniques, i.e., x-ray diffraction, differential thermal analysis, infrared, and temperature-dependent Raman spectroscopy, have been used to follow the thermal behavior of the samples. When the bulk xerogels begin to change from a nanocrystalline phase to the orthorhombic α-V2O5, in the temperature range 280 to 300 °C, a growth of vanadium oxide nanotubes also occurs, while at higher temperatures the crystallization into the α phase prevails. A slightly different evolution is observed for heat treated thin films, which show a structure containing polyvanadate chains near room temperature. They also present a growth of nanotubes for intermediate temperatures and a complete crystallization into the α phase when the temperature is further increased.
A flagellated, bottom-heavy micro-organism's swimming direction in a shear flow is determined from a balance between the gravitational and viscous torques (gyrotaxis). Hitherto, the cell has been assumed to be a spheroid and the flagella have been neglected. Here we use resistive-force theory to calculate both the magnitude and the direction of a biflagellate cell's swimming velocity and angular velocity relative to the fluid when there is an arbitrary linear flow far from the cell. We present an idealized model for the flagellar beat but, in calculating the velocity of the fluid relative to an element of a flagellum, the presence of the cell body is not neglected. Results are given for the case of a spherical cell body whose flagella beat in a vertical plane, when the ambient linear flow is in the same vertical plane. Results show that resistive-force theory can be used for organisms where the cell body has significant effect on the flow past the flagella and that the viscous torque on the flagella is a significant term in the torque balance equations. A model is presented for the calculation of a cell's velocity and angular velocity in a shear flow which is valid up to high magnitudes of rate of strain or vorticity. The main application of the results will be to modify a recent continuum model for suspensions of gyrotactic micro-organisms (Pedley & Kessler 1990).
Nanocrystal memories are widely invoked as potential solutions to overcome the scaling limitations of conventional FLASH memories beyond the 80nm technology node. In this study, the deposition of uniform silicon nanocrystals has been developed and optimized in a commercially available vertical furnace, an A400 from ASM.
It has been shown that low pressure chemical vapor deposition (LPCVD) of nanocrystals is feasible in a batch reactor but with a bad size dispersion of the silicon nanocrystals. To improve the size dispersion of the nanocrystals, a novel 2-step process with silane was introduced. In the conventional 1-step process, the oxide surface is exposed to silane at the same partial pressure and temperature during both nucleation and growth of the silicon nanocrystals. In this novel 2-step process, the surface is first exposed briefly to silane at a higher temperature (580–600°C) and following that, the temperature is lowered to allow selective growth on the existing silicon nuclei over the oxide surface. With such an approach, the nucleation step can be separated from the growth step and consequently the size dispersion can be improved by 50%.