Concentration Dependence of Elastic and Viscoelastic Properties of Aqueous Solutions of Ficoll and Bovine Serum Albumin by Brillouin Light Scattering Spectroscopy.

The cellular environment is crowded with macromolecules of different shapes and sizes. The effect of this macromolecular crowding has been studied in a variety of synthetic crowding environments: two popular examples are the compact colloid-like Ficoll macromolecule and the globular protein bovine serum albumin (BSA). Recent studies have indicated that a significant component of bound or surface-associated water in these crowders reduces the available free volume. In this work, Brillouin light scattering experiments were performed on aqueous solutions of Ficoll 70 and Ficoll 400 with concentrations ranging from 1 to 35 wt % and BSA with concentrations of 1 to 27 wt %. From the dependence of spectral peak parameters on polymer concentration, we determined fundamental solution properties: hypersound velocity, adiabatic bulk modulus and compressibility, apparent viscosity, and hypersound attenuation. The existing theory that ignores intermolecular interactions can capture only the observed linear trends in the frequency shift up to a threshold concentration, beyond which a quadratic term accounting for intermolecular interactions is necessary. This likely indicates a transition from the dilute to semidilute regime. In the Ficoll solutions (but not BSA), we see evidence for a central mode, which is indicative of relaxation in the hydration shell of Ficoll.

A clinico-radiological review of chronic non-bacterial osteomyelitis in paediatrics, adolescents, and adults: demystifying a forgotten differential.

Chronic non-bacterial osteomyelitis (CNO), also known as non-bacterial osteitis, is a chronic autoinflammatory disease of unknown aetiology that primarily occurs in the paediatric population, although rare cases of adult-onset disease also exist. CNO has non-specific clinical and radiological presentations, and the affected population often present with bone pain of insidious onset secondary to sterile bony inflammation that can be associated with swelling, focal tenderness, and warmth at the affected sites. The pattern of bony involvement appears to be dependent on the age of onset, with adults frequently having axial skeletal lesions and children and adolescents often being affected in the appendicular skeletal sites. CNO is a diagnosis of exclusion, and imaging is heavily relied on to identify and characterise the bony lesions in addition to exclude diseases that can mimic CNO. Magnetic resonance imaging is often the reference standard with biochemical and histopathological findings being complementary. Although combining imaging methods can be used to facilitate the diagnosis, a single technique could be adequate depending on the clinical picture. Given the relatively rare incidence of CNO, limited awareness of the disease among care providers, and its similarity in clinical and radiological presentation to various bony diseases, there are often long delays in diagnosis, with adults being unfavourably affected compared to paediatrics and adolescents. This review of CNO will describe the condition, overview its clinical presentation, highlight the radiological features, and emphasise clinical pearls that can aid in diagnosis and ruling out the mimics.

Temperature dependence of the viscoelastic properties of a natural gastropod mucus by Brillouin light scattering spectroscopy.

Brillouin spectroscopy was used to probe the viscoelastic properties of a natural gastropod mucus at GHz frequencies over the range -11 °C ≤ T ≤ 52 °C. Anomalies in the temperature dependence of mucus longitudinal acoustic mode peak parameters and associated viscoelastic properties at T = -2.5 °C, together with the appearance of a peak due to ice at this temperature, suggest that the mucus undergoes a phase transition from a viscous liquid state to one in which liquid mucus and solid ice phases coexist. Failure of this transition to proceed to completion even at -11 °C is attributed to glycoprotein-water interaction. The temperature dependence of the viscoelastic properties and the phase behaviour suggest that water molecules bind to glycoprotein at a temperature above the onset of freezing and that the reduced ability of this bound water to take on a configuration that facilitates freezing is responsible for the observed freezing point depression and gradual nature of the liquid-solid transition.

Loneliness in the workplace: a mixed-method systematic review and meta-analysis.

BACKGROUND: Loneliness is a risk factor for a range of mental and physical health problems and has gained increasing interest from policy-makers and researchers in recent years. However, little attention has been paid to loneliness at work and its implications for workers and employers. AIMS: Identify workplace, health and personal factors associated with workplace loneliness. METHODS: We searched five databases (PubMed, MEDLINE, EMBASE, PsycINFO and EBSCO Business Source Complete) for relevant articles published from 1 January 2000 to 23 February 2023. Quantitative data were synthesized using narrative synthesis and random-effects meta-analysis of correlation coefficients. Qualitative data were synthesized using thematic synthesis. Evidence quality was appraised using the Mixed-Methods Appraisal Tool. RESULTS: We identified 49 articles meeting the inclusion criteria. Pooled results indicate that workplace loneliness was associated with lower job performance (r = -0.35, 95% CI -0.49, -0.21), reduced job satisfaction (r = -0.34, 95% CI -0.44, -0.24), worse worker-manager relationship (r = -0.31, 95% CI -0.38, -0.24) and elevated burnout (r = 0.39, 95% CI 0.25, 0.51). Qualitative results suggest links between loneliness and inadequate workplace social interactions and mental health problems. As most studies used cross-sectional data and few adjusted for potential confounders, the direction and robustness of the associations remain untested. CONCLUSIONS: Our results indicate that loneliness is associated with poor occupational functioning and well-being among workers. Results also show that loneliness is associated with modifiable aspects of the work environment, suggesting that the workplace may offer a fruitful avenue for interventions targeting loneliness.

Solvent-Assisted Hot Melt Extrusion of a Thermally Labile, High Melting Point Compound.

Molecular dispersions are a highly effective method of increasing bioavailability for a poorly soluble active pharmaceutical ingredient (API) and can be prepared on a large scale by hot melt extrusion (HME). Processing thermally labile active pharmaceutical ingredients (APIs) via HME is generally more difficult, with operating temperatures limited to below that of the API melting point. API melting is considered essential to facilitate the formation of a fully homogeneous amorphous system. Processing below the melting point renders the system much more susceptible to residual crystalline content; hence, HME is not suitable for APIs which degrade upon melting. In the following work, meloxicam (MEL) was used as a model API, possessing properties of high melting temperature and thermal lability. In this proof of concept work, a modified HME method, termed solvent-assisted HME, was used to overcome this issue and prepare an amorphous solid dispersion using HME, wherein a solvent was incorporated in the formulation blend during extrusion and removed post-processing. Formulations containing 10%wt meloxicam (MEL) and 90%wt polyvinylpyrrolidone vinyl acetate (PVPVA) copolymer were extruded using a twin-screw extruder at temperatures below the melting point of MEL. Dimethylformamide (DMF) solvent was added directly into the extruder barrel through a liquid addition port, resulting in extrudate products having a higher conversion of API to the amorphous form. The incorporation of solvent allowed a significant reduction in processing temperatures due to its increased mobility, while also driving the conversion of the API to its amorphous form. The solvent was successfully reduced through a secondary drying step using a vacuum oven. This advancement has demonstrated the potential for thermally labile APIs to be processed via HME expanding the applications of this technology.

A mixed methods pilot and feasibility open trial of internet-delivered cognitive behaviour therapy (iCanADAPT Advanced) for people with advanced cancer with depression and/or anxiety.

PURPOSE: Evaluate the feasibility, acceptability and potential efficacy of a form of online therapy for clinical depression and/or anxiety in people living with advanced cancer. METHODS: A single-arm open trial of a six-lesson clinician-supervised, internet-delivered cognitive behavioural therapy (iCBT) transdiagnostic intervention (iCanADAPT Advanced) was undertaken. Qualitative (semi-structured telephone interview conducted at 3-months) and quantitative data (questionnaires collected at pre-, post-, and 3-month follow-up) were analysed. RESULTS: 27 participants partook (26 women, 56% breast cancer, mean age 56yo; average number of mental health diagnoses 1.8, with majority (81%) meeting criteria for generalised anxiety disorder). Feasibility - Unanticipated numbers (48%) of participants had physical health deterioration (cancer progression or death). iCBT had high adherence overall (completion rates: 37% did 6 lessons; 70% did 4 lessons) but adherence was higher for those whose cancer remained stable (completion rates: 43% did 6 lessons; 85% did 4 lessons). Acceptability - the intervention was acceptable to the majority of participants, with high treatment satisfaction. Advisory data was achieved regarding future versions. Potential efficacy - regardless of physical health status, participants who completed the iCBT showed a significant decrease over time in anxiety and depression symptoms. CONCLUSIONS: Online therapies may be useful in assisting those living with advanced cancer dealing with clinical depression and anxiety disorders. The specific modality of clinician supervised iCBT has significant potential to be a suitable modality of online therapy.

Randomised controlled trial of internet-delivered cognitive behaviour therapy for clinical depression and/or anxiety in cancer survivors (iCanADAPT Early).

PURPOSE: To evaluate internet-delivered cognitive behavioural therapy (iCBT) on clinical depression and/or anxiety, distress, fear of cancer recurrence, and quality of life in cancer survivors. METHODS: Random assignation of 114 participants to iCBT or treatment-as-usual (TAU). The clinician-supervised iCBT program (iCanADAPT Early) consisted of eight lessons over 16 weeks. Self-report questionnaires occurred at baseline, midpoint, and posttreatment for both groups with 3-month follow-up for iCBT participants. A mixed modelling approach to compare groups occurred. RESULTS: iCBT was superior to TAU on all outcome measures at posttreatment. Compared with TAU, the iCBT group showed a significant decrease over time in anxiety and depression symptoms (primary outcome, Hospital Anxiety and Depression Scale, Hedges g = 1.51). Additionally the iCBT group had significantly lower general distress (Kessler-10, g = 1.56), fear of cancer recurrence (Fear of Cancer Recurrence Inventory, g = 0.39), and significantly higher quality of life (Functional Assessment of Cancer Therapy-General, g = 0.74) at posttreatment compared with the TAU group. High adherence and satisfaction were found for iCBT with low clinician time. CONCLUSION: Clinician-supervised iCBT has significant benefits for cancer survivors with clinical depression and anxiety disorders.

Meanings and feelings of (Im)mobility in later life: Case study insights from a 'New Mobilities' perspective.

Understandings of mobility and immobility shape research and responses to late life. Yet, the underlying assumptions about mobility often remain fixed on ideas of function and physical ability. The 'new mobilities' paradigm shifts this analysis by focusing on the importance and experience of mobility as a thing in itself rather than a means to an end, and to the complex enactments that operate across a range of relationships, settings, sites, and contexts. This paper provides insight from an embedded case study method comprised of fifteen exploratory interviews with older people at three social locations, including 5 individuals considered 'frail', 5 people who are aging with a disability, and 5 older people who self-identify as 'active'. Considered together and in contrast, the findings from these three distinct but related embedded case sites, viewed from a 'new mobilities' perspective, can help to understand (im)mobility as an embodied experience that is situated within and across social and political contexts, and can explicate how relations of power enhance the mobility of some, and the immobility of others. We conclude that the 'new mobilities' approach introduces ideas to overcome limitations of distance, movement, and place, and in doing so, serves to redefine what it means to be mobile while aging.

The development of an inline Raman spectroscopic analysis method as a quality control tool for hot melt extruded ramipril fixed-dose combination products.

Currently in the pharmaceutical industry, continuous manufacturing is an area of significant interest. In particular, hot-melt extrusion (HME) offers many advantages and has been shown to significantly reduce the number of processing steps relative to a conventional product manufacturing line. To control product quality during HME without process interruption, integration of inline analytical technology is critical. Vibrational spectroscopy (Raman, NIR and FT-IR) is often employed and used for real-time measurements because of the non-destructive and rapid nature of these analytical techniques. However, the establishment of reliable Process Analytical Technology (PAT) tools for HME of thermolabile drugs is challenging. Indeed, the Raman effect is inherently weak and might be subject to interference. Moreover, during HME, heating and photodecomposition can occur and disrupt spectra acquisition. The aim of this research article was to explore the use of inline Raman spectroscopy to characterise a thermolabile drug, ramipril (RMP), during continuous HME processing. Offline measurements by HPLC, LC-MS and Raman spectroscopy were used to characterise RMP and its main degradation product, ramipril-diketopiperazine (RMP-DKP, impurity K). A set of HME experiments together with inline Raman spectroscopic analyses were performed. The feasibility of implementing inline Raman spectroscopic analysis to quantify the level of RMP and RMP-DKP in the extrudate was addressed. Two regions in the Raman spectrum were selected to differentiate RMP and RMP-DKP. When regions were combined, a principle component analysis (PCA) model defined by these two main components (PC 1 = 50.1% and PC 2 = 45%) was established. Using HPLC analyses, we were able to confirm that the PC 1 score was attributed to the level of RMP-DKP, and the PC 2 score was related to the RMP drug content. Investigation of the PCA scatterplot indicated that HME processing temperature was not the only factor causing RMP degradation. Additionally, the plasticiser content, feeding speed and screw rotating speed contributed to RMP degradation during HME processing.

Fixed Dose Combination Formulations: Multilayered Platforms Designed for the Management of Cardiovascular Disease.

Hyperlipidaemia is considered as one of the main risk factors associated with cardiovascular diseases (CVDs). Among different lipid-lowering agents used to manage hyperlipidaemia, statins are highly prescribed for management of hyperlipidaemia with simvastatin being one of the most common. Simvastatin is susceptible to extensive metabolism by CYP450 3A4 and 3A5, which are expressed both in the liver and the gastrointestinal tract. Nevertheless, the localization of these enzymes is site-dependent with lower concentration at the distal/proximal regions of the small intestine/colon. In addition to statins, medications such as antihypertensive agents and anticoagulants are introduced as adjuvants, for the treatment of cardiovascular disease. The aim of this study was to design a bilayer delivery system capable of delivering biphasic release of simvastatin and aspirin, within a fixed dose combination. A delayed release platform based on a combination of anionic polymers prepared using hot-melt extrusion was developed to delay the release of simvastatin. An optimized formulation tested for dissolution performance clearly demonstrated an ability to delay the release of simvastatin. In addition, an immediate release layer based on Kollidon VA64 was successfully developed to deliver aspirin. Both formulations were then manufactured as a bilayer drug delivery system (tablets and coextrudates), and the release performance was examined. On the basis of the obtained results, these formulations may be used as a platform for delivering a wide range of medications in a biphasic manner.

Pluto's Interaction With Energetic Heliospheric Ions.

Pluto energies of a few kiloelectron volts and suprathermal ions with tens of kiloelectron volts and above. We measure this population using the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument on board the New Horizons spacecraft that flew by Pluto in 2015. Even though the measured ions have gyroradii larger than the size of Pluto and the cross section of its magnetosphere, we find that the boundary of the magnetosphere is depleting the energetic ion intensities by about an order of magnitude close to Pluto. The intensity is increasing exponentially with distance to Pluto and reaches nominal levels of the interplanetary medium at about 190R P distance. Inside the wake of Pluto, we observe oscillations of the ion intensities with a periodicity of about 0.2 hr. We show that these can be quantitatively explained by the electric field of an ultralow-frequency wave and discuss possible physical drivers for such a field. We find no evidence for the presence of plutogenic ions in the considered energy range.

A comparative study between hot-melt extrusion and spray-drying for the manufacture of anti-hypertension compatible monolithic fixed-dose combination products.

The purpose of this work was to investigate the application of different advanced continuous processing techniques (hot melt extrusion and spray drying) to the production of fixed-dose combination (FDC) monolithic systems comprising of hydrochlorothiazide and ramipril for the treatment of hypertension. Identical FDC formulations were manufactured by the two different methods and were characterised using powder X-ray diffraction (PXRD) and modulated differential scanning calorimetry (mDSC). Drug dissolution rates were investigated using a Wood's apparatus, while physical stability was assessed on storage under controlled temperature and humidity conditions. Interestingly both drugs were transformed into their amorphous forms when spray dried, however, hydrochlorothiazide was determined, by PXRD, to be partially crystalline when hot melt extruded with either polymer carrier (Kollidon® VA 64 or Soluplus®). Hot melt extrusion was found to result in significant degradation of ramipril, however, this could be mitigated by the inclusion of the plasticizer, polyethylene glycol 3350, in the formulation and appropriate adjustment of processing temperature. The results of intrinsic dissolution rate studies showed that hot-melt extruded samples were found to release both drugs faster than identical formulations produced via spray drying. However, the differences were attributable to the surface roughness of the compressed discs in the Wood's apparatus, rather than solid state differences between samples. After a 60-day stability study spray dried samples exhibited a greater physical stability than the equivalent hot melt extruded samples.

Computer therapy for the anxiety and depression disorders is effective, acceptable and practical health care: An updated meta-analysis.

BACKGROUND: A 2010 meta-analysis of internet-delivered CBT (iCBT) RCTs argued 'computer therapy for the anxiety and depressive disorders was effective, acceptable and practical health care' without data on effectiveness or practicality in routine practice. METHODS: Databases, reviews and meta-analyses were searched for randomised controlled trials of cCBT or iCBT versus a control group (care as usual, waitlist, information control, psychological placebo, pill placebo, etc.) in people who met diagnostic criteria for major depression, panic disorder, social anxiety disorder or generalised anxiety disorder. Number randomised, superiority of treatment versus control (Hedges'g) on primary outcome measure, length of follow-up, follow up outcome, patient adherence and satisfaction/harm were extracted; risk of bias was assessed. A search for studies on effectiveness of iCBT in clinical practice was conducted. RESULTS: 64 trials were identified. The mean effect size (efficacy) was g = 0.80 (NNT 2.34), and benefit was evident across all four disorders. Improvement was maintained at follow-with good acceptability. Research probity was good, and bias risk low. In addition, nine studies comparing iCBT with traditional face-to-face CBT and three comparing iCBT with bibliotherapy were identified. All three modes of treatment delivery appeared equally beneficial. The results of effectiveness studies were congruent with the results of the efficacy trials. LIMITATIONS: Studies variably measured changes in quality of life and disability, and the lack of comparisons with medications weakens the field. CONCLUSIONS: The conclusions drawn in the original meta-analysis are now supported: iCBT for the anxiety and depressive disorders is effective, acceptable and practical health care.

iCanADAPT Early protocol: randomised controlled trial (RCT) of clinician supervised transdiagnostic internet-delivered cognitive behaviour therapy (iCBT) for depression and/or anxiety in early stage cancer survivors -vs- treatment as usual.

BACKGROUND: This RCT with two parallel arms will evaluate the efficacy of an internet-delivered transdiagnostic cognitive behavioural therapy (iCBT) intervention for the treatment of clinical depression and/or anxiety in early stage cancer survivors. METHODS/DESIGN: Early stage cancer survivors will be recruited via the research arm of a not-for-profit clinical research unit and randomised to an intervention (iCBT) group or a 'treatment as usual' (TAU) control group. The minimum sample size for each group is 45 people (assuming effect size > 0.6, power of 80%, and alpha at .05), but 10% more will be recruited to account for attrition. A solitary or cumulative diagnosis(es) of Major Depressive Episode (current), Generalised Anxiety Disorder, Illness Anxiety Disorder, Panic Disorder, Agoraphobia, and/or Adjustment disorder will be determined using modules from the Anxiety Disorders Interview Schedule for DSM-5. Depression and anxiety levels with be measured via the total score of the Hospital Anxiety and Depression scale (HADS-T), the primary outcome measure. Secondary measures will include the Kessler 10 to measure general distress, the Fear of Cancer Recurrence Inventory (FCRI) to measure the specific fear of cancer recurrence and the Functional Assessment of Cancer Therapy, General Version 4 (FACT-G) for self-report of physical, social, emotional and functional well-being. iCBT participants will complete the measures before lessons 1 and 5, at post-treatment and at 3-month follow-up. The TAU group will complete similar measures at weeks 1, 8 and 16 of the waiting period. Program efficacy will be determined using intent-to-treat mixed models. Maintenance of gains will be assessed at 3-month follow-up. Mediation analyses using PROCESS will be used to examine the association between change in depressive and anxious symptoms over time and changes in FCRI and FACT-G QOL in separate analysis. DISCUSSION: This is the first RCT looking at iCBT specifically for clinical depression and/or anxiety in a cancer population. Findings will help to direct the role of iCBT in streamlined psycho-social care pathways. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12616000231448, registered 19th February 2016 ( www.anzctr.org.au ). This trial protocol is in compliance with the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) guidelines.

Acceptability of an internet cognitive behavioural therapy program for people with early-stage cancer and cancer survivors with depression and/or anxiety: thematic findings from focus groups.

PURPOSE: We developed an eight-lesson internet-delivered CBT (iCBT) program targeting anxiety and depression in early-stage cancer and cancer survivors. To explore the acceptability of the program, we showed volunteers the first two lessons and asked for their views. METHODS: Focus groups (n = 3) and individual interviews (n = 5) were undertaken with 15 participants (11 survivors) with mainly breast (11 of the 15) cancer, who had reviewed intervention materials. Participants were asked to consider the acceptability of the iCBT program content and implementation design (timing, duration). Semi-structured questions guided discussion. Thematic analysis was conducted of participant reactions to the acceptability and/or suitability of materials created for use in a psychological intervention. We took a data-driven (inductive) approach to semantic theme development across the data set. RESULTS: Participants reported high acceptability of the internet delivery format, good engagement and user-friendly material. Participants were broadly supportive of combining depression and anxiety iCBT resources for early-stage cancer patients and survivors. Participants further indicated that a separate course would be needed to address the needs of patients with advanced stage disease. CONCLUSIONS: Participants welcomed the general development of an internet-delivered CBT intervention program to treat patients with clinical depression and/or anxiety. Furthermore, the sessions reviewed were highly acceptable to all participants. Study findings informed researchers on the development of iCBT resources for the cancer community.

The "Puck" energetic charged particle detector: Design, heritage, and advancements.

Energetic charged particle detectors characterize a portion of the plasma distribution function that plays critical roles in some physical processes, from carrying the currents in planetary ring currents to weathering the surfaces of planetary objects. For several low-resource missions in the past, the need was recognized for a low-resource but highly capable, mass-species-discriminating energetic particle sensor that could also obtain angular distributions without motors or mechanical articulation. This need led to the development of a compact Energetic Particle Detector (EPD), known as the "Puck" EPD (short for hockey puck), that is capable of determining the flux, angular distribution, and composition of incident ions between an energy range of ~10 keV to several MeV. This sensor makes simultaneous angular measurements of electron fluxes from the tens of keV to about 1 MeV. The same measurements can be extended down to approximately 1 keV/nucleon, with some composition ambiguity. These sensors have a proven flight heritage record that includes missions such as MErcury Surface, Space ENvironment, GEochemistry, and Ranging and New Horizons, with multiple sensors on each of Juno, Van Allen Probes, and Magnetospheric Multiscale. In this review paper we discuss the Puck EPD design, its heritage, unexpected results from these past missions and future advancements. We also discuss high-voltage anomalies that are thought to be associated with the use of curved foils, which is a new foil manufacturing processes utilized on recent Puck EPD designs. Finally, we discuss the important role Puck EPDs can potentially play in upcoming missions.

Does Internet-based guided-self-help for depression cause harm? An individual participant data meta-analysis on deterioration rates and its moderators in randomized controlled trials.

BACKGROUND: Almost nothing is known about the potential negative effects of Internet-based psychological treatments for depression. This study aims at investigating deterioration and its moderators within randomized trials on Internet-based guided self-help for adult depression, using an individual patient data meta-analyses (IPDMA) approach. METHOD: Studies were identified through systematic searches (PubMed, PsycINFO, EMBASE, Cochrane Library). Deterioration in participants was defined as a significant symptom increase according to the reliable change index (i.e. 7.68 points in the CES-D; 7.63 points in the BDI). Two-step IPDMA procedures, with a random-effects model were used to pool data. RESULTS: A total of 18 studies (21 comparisons, 2079 participants) contributed data to the analysis. The risk for a reliable deterioration from baseline to post-treatment was significantly lower in the intervention v. control conditions (3.36 v. 7.60; relative risk 0.47, 95% confidence interval 0.29-0.75). Education moderated effects on deterioration, with patients with low education displaying a higher risk for deterioration than patients with higher education. Deterioration rates for patients with low education did not differ statistically significantly between intervention and control groups. The benefit-risk ratio for patients with low education indicated that 9.38 patients achieve a treatment response for each patient experiencing a symptom deterioration. CONCLUSIONS: Internet-based guided self-help is associated with a mean reduced risk for a symptom deterioration compared to controls. Treatment and symptom progress of patients with low education should be closely monitored, as some patients might face an increased risk for symptom deterioration. Future studies should examine predictors of deterioration in patients with low education.

Raman and Brillouin scattering studies of bulk 2H-WSe2.

Raman and Brillouin spectroscopy were used to probe optic and acoustic phonons in bulk 2H-WSe2. Raman spectra collected under different polarization conditions allowed assignment of spectral peaks to various first- and second-order processes. In contrast to some previous studies, a Raman peak at ∼259 cm(-1)was found not to be due to the A(1g) mode but to a second-order process involving phonons at either the M or K point of the Brillouin zone. Resonance effects due to excitons were also observed in the Raman spectra. Brillouin spectra of 2H-WSe2 contain a single peak doublet arising from a Rayleigh surface mode propagating with a velocity of [Formula: see text] m s(-1). This value is comparable to that estimated from Density Functional Theory calculations and also to those for the transition metal diselenides 2H-TaSe2 and 2H-NbSe2. Unlike these two materials, however, peaks arising from scattering via the elasto-optic mechanism were not observed in Brillouin spectra of WSe2 despite its lower opacity.

Comparative study of the biodegradability of porous silicon films in simulated body fluid.

The biodegradability of oxidized microporous, mesoporous and macroporous silicon films in a simulated body fluid with ion concentrations similar to those found in human blood plasma were studied using gravimetry. Film dissolution rates were determined by periodically weighing the samples after removal from the fluid. The dissolution rates for microporous silicon were found to be higher than those for mesoporous silicon of comparable porosity. The dissolution rate of macroporous silicon was much lower than that for either microporous or mesoporous silicon. This is attributed to the fact that its specific surface area is much lower than that of microporous and mesoporous silicon. Using an equation adapted from [Surf. Sci. Lett. 306 (1994), L550-L554], the dissolution rate of porous silicon in simulated body fluid can be estimated if the film thickness and specific surface area are known.