An 8-Bit Digitally Controlled Programmable Phase Shifter Circuit for Sinusoidal Signals with 252∘ Phase Control Range

In this paper, the synthesis, design, and implementation of a programmable phase shifter circuit for sinusoidal signals is presented. The proposed circuit, built-up herein with operational amplifiers (OPAMPs), high precision resistors and low voltage switches, consists of a digitally controlled amplitude attenuator in combination with a single-tone orthogonalizer. Experimental results agree with theoretical background: the attained phase range was 252^° in 256 steps with a median step of 0.9^°. The inaccuracy of the circuit was determined to be of 0.03 %. Contrary to other OPAMP approaches for sinusoidal signals reported in the literature and based on a first-order all-pass filter structure, the approximation suggested in this work is based on a different concept. The achieved results demonstrate the functionality of the system for the case of a sinusoidal signal with frequency of 1 kHz. Notwithstanding, the proposed architecture can be extended to operate at higher frequencies by using different building blocks with larger bandwidth. Furthermore, it can be extended as well to work out with other periodic input waveforms, like triangular shapes or square waves, with the use of an appropriate orthogonalizer.     

A one-pot ultrasound-assisted water extraction/cyclodextrin encapsulation of resveratrol from Polygonum cuspidatum

The ultrasound-assisted extraction (UAE) of resveratrol and other polyphenols from Polygonum cuspidatum has been carried out with the aim of developing an efficient and eco-friendly extraction process. The finely milled roots were sonicated (titanium horn, 19.5 kHz) in methanol, in different cyclodextrin water solutions [β-cyclodextrin (β-CD) or hydroxypropyl β-CD (HPβ-CD)] and also in pure water. UAE dramatically increased the yields and cut down extraction times compared to conventional extraction under stirring. Outstanding results have been achieved with the β-CD solution (1.5% w/w); in fact HPLC analysis showed that the selective inclusion properties of CDs toward phenolic stilbenes gave a much cleaner analytical extract profile. This green method gave 7.51 mg of total resveratrol (free + cleaved polydatin glucoside) per gram of dry plant. Thanks to polyphenol encapsulation within CDs, this extract showed excellent water dispersibility, higher stability and an antioxidant power which is comparable to that of the MeOH extract (DPPH, ORAC_FL). These important features should pave the road for its application in food supplements or phytochemical preparations.     

Client-specific counselor self-efficacy in novice counselors: Relation to perceptions of session quality.

Two versions of a counselor self-efficacy (CSE) measure were administered to 110 prepracticum counselors: a general version, assessing perceived capability to perform basic helping skills and manage the session process with clients generally; and a client-specific version, tapping capability to perform the same behaviors with a specific, current client. Client-specific CSE was found to (a) relate moderately to strongly with general CSE over the course of four counseling sessions, (b) increase significantly over sessions, and (c) account for unique variance in counselors' evaluations of the quality of their sessions. Although it was not a useful direct predictor of clients' session ratings, higher client-specific CSE was associated with greater congruence between counselors' and clients' perceptions of session quality. Implications for further research and training are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polypyrrole materials doped with weakly coordinating anions: influence of substituents and the fate of the doping anion during the overoxidation process

The influence of weakly coordinating anions with different shapes and substituents has been studied to get the overoxidation resistance limit of the material, ORL. The anions utilized are derivatives of [Co(C₂B₉H₁₁)₂]⁻, [B₁₂H₁₂]²⁻ and [B₁₂H₁₁NH₃]⁻. The following tendencies have been established (1) boron cluster monoanions are to date the anions that offer the highest stability to overoxidation of PPy doped materials (2) the ORL stability of the material can not be attributed only to the shape of the cluster (3) monoanionic clusters are far superior than dianionic to get an ORL rise (4) cluster charge density reduction results in ORL rise as has been observed in [Co(C₂B₉H₁₁)₂]⁻ after incorporation of electron-withdrawing substituents with no electron back-donation (5) globular, rigid and large monoanions are less suitable for enhanced ORL values than elongated and non-rigid species (6) adequate anion's substitution produce a rise in the ORL of the material, thus polyether side-arms are beneficial with [Co(C₂B₉H₁₁)₂]⁻, whereas, T-shaped methylaryl groups are appealing in [B₁₂H₁₁NH₃]⁻ based materials, respectively, (7) substituents on the anions usually imply higher difficulty in the materials' growth. The high boron contents in these materials has permitted to learn on the fate of the doping anions during the overoxidation process. There is a built-up of the concentration of the doping anion in the electrolyte near surface area, whereas, a depletion is observed in the nearest inner layers.     

A narrative and meta-analytic review of helping skills training: Time to revive a dormant area of inquiry.

The authors review previous narrative and meta-analytic reviews on the effectiveness of overall helping skills training programs. The authors then review narrative reviews and conduct a new meta-analysis of specific methods used to teach helping skills within these programs. Our meta-analysis found that, in the aggregate, training methods substantially outperformed no training conditions, and that effect sizes did not vary as a function of trainee educational level (graduate vs. undergraduate students) or the type of criterion measure (interview-based vs. analogue-based empathy measures). Direct comparison of the training methods revealed that modeling outperformed instruction and feedback, and multimethod outperformed single-method training. The authors critique the literature and suggest that the studies in the helping skills literature generally fail to meet contemporary methodological standards, thereby limiting the conclusions that can be drawn. The authors appeal for better research on helping skills training, especially as it is currently practiced. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prefrontal control of trace versus delay eyeblink conditioning: Role of the unconditioned stimulus in rabbits (Oryctolagus cuniculus).

The conditioned eyeblink (EB) response was studied with trace conditioning procedures in rabbits (Oryctolagus cuniculus) with lesions to the medial prefrontal cortex (mPFC) or sham lesions. Three experiments were performed in which either periorbital shock or a corneal airpuff served as the unconditioned stimulus (US) in separate groups of sham or mPFC-lesioned rabbits. Acquisition of the EB conditioned response (CR) was faster and reached a higher asymptote with the eyeshock US than with the airpuff US. However, mPFC lesion-induced trace conditioning deficits were obtained only in the groups that received the airpuff US. All rabbits showed normal delay conditioning and extinction. These results suggest that mPFC mediates trace EB conditioning when emotional arousal is low. However, in circumstances when emotional arousal may be high (i.e., during exposure to aversive periorbital shock), other structures (such as amygdala) may be activated to permit learning even in the absence of input from mPFC. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of a toasted durum whole meal in the production of a traditional Italian pasta: chemical, mechanical, sensory and image analyses

The characterisation of traditional Italian pasta obtained by mixing amounts of toasted whole meal with re-milled semolina and other ingredients was obtained by means of physico-chemical, rheological, mechanical, sensory and image analyses. The toasted meal showed higher ash, fibre and protein contents than re-milled semolina. The replacement of percentages of re-milled semolina with the toasted meal and soft flour increased tenacity and decreased extensibility and strength, making the dough less suitable for pasta-making. The P / L values were indices of high starch damage. The replacement of part of re-milled semolina and water with toasted whole wheat meal, soft flour and eggs increased the optimal cooking time and the amount of water absorbed during cooking but made the other cooking parameters worse. The image analysis provided evidence of the changes induced by the use of toasted wholemeal, soft flour and eggs in the microscopic structure of pasta protein and starch.     

A New Application of Solvent Extraction to Separate Copper from Extreme Acid Mine Drainage Producing Solutions for Electrochemical and Biological Recovery Processes

Over the last decade, AMD waters have gained more attention as a potential source of metals due to the emerging need to recover or recycle metals from secondary resources. Metals recovery supports sustainability and the development of a circular economy with benefits for resource conservation and the environment. In this study, five extractants (Acorga M5640, LIX 54, LIX 622, LIX 622 N, and LIX 864) diluted (15% (v/v)) in Shell GTL with 2.5% (v/v) octanol were compared and evaluated for Cu recovery from an extreme AMD sample (5.3?±?0.3 g/L Cu) collected at the inactive São Domingos Mine in the Iberian Pyrite Belt of Portugal. Of the five extractants, Acorga M5640 showed the best selective efficiency. Further tests showed that 30% (v/v) of this extractant was able to selectively extract ≈ 96.0% of the Cu from the AMD in one extraction step and all of the remaining Cu (to below detection) in three steps. Among the different stripping agents tested, 2 M sulfuric acid was the most efficient, with ≈ 99% of the Cu stripped, and the recyclability of the organic phase was confirmed in five successive cycles of extraction and stripping. Furthermore, contact time tests revealed that the extraction kinetics allows the transfer of ≈ 97% of the Cu in 15 min, and aqueous to organic phase ratios tests demonstrated a maximum loading capacity of ≈ 16 g/L Cu in the organic phase. Raising the concentration of Cu in the stripping solution (2 M sulfuric acid) to ≈ 46 g/L through successive striping steps showed the potential to recover elemental Cu using traditional electrowinning. Finally, a biological approach for Cu recovery from the stripping solution was evaluated by adding the supernatant of a sulfate-reducing bacteria culture to make different molar ratios of biogenic sulfide to copper; ratios over 1.75 resulted in precipitation of more than 95% of the Cu as covellite nanoparticles.

Graphical Abstract

     

Moving Out of Home Ownership in Later Life: The Influence of the Family and Housing Careers

Home ownership is often regarded as the preferred housing tenure; however, situations in parallel life-course careers might make moving to a rental home necessary or attractive to home owners. Retrospective data from the SHARELIFE survey were used to study the short- and long-term impact of situations and disruptions in the family and housing careers on leaving home ownership at middle (45–64) and older ages (65–80) in Denmark, Sweden and the Netherlands. We found that directly after separation and widowhood, the likelihood of leaving home ownership was the greatest. However, more than 10 years after separation and widowhood, individuals were still significantly more likely to leave ownership than those in their first marriage. Furthermore, late first childbirth and early first-time home ownership were associated with lower chances of leaving home ownership. We conclude that situations and changes in family and housing careers have both a short-term and a long-term impact on the likelihood of moving out of home ownership.