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Biomedical subjects

S Prawer

Publications and source records attributed to S Prawer.

18 recordsLinked to original sources
PubMed2006

Stark shift control of single optical centers in diamond.

Lifetime-limited optical excitation lines of single nitrogen-vacancy (NV) defect centers in diamond have been observed at liquid helium temperature. They display unprecedented spectral stability over many seconds and excitation cycles. Spectral tuning of the spin-selective optical resonances was performed via the application of an external electric field (i.e., the Stark shift). A rich variety of Stark shifts were observed including linear as well as quadratic components. The ability to tune the excitation lines of single NV centers has potential applications in quantum information processing.

Journal Article↗
PubMed2005

Stable superhydrophobic surface via carbon nanotubes coated with a ZnO thin film.

We report the formation of a stable superhydrophobic surface via aligned carbon nanotubes (CNTs) coated with a zinc oxide (ZnO) thin film. The CNT template was synthesized by chemical vapor deposition on an Fe-N catalyst layer. The ZnO film, with a low surface energy, was deposited on the CNT template by the filtered cathodic vacuum arc technique. Contact angle measurement reveals that the surface of the ZnO-coated CNTs is superhydrophobic with water contact angle of 159 degrees . Unlike the uncoated CNTs surface, the ZnO-coated CNTs surface shows no sign of water seepage even after a prolonged period of time. The wettability of the surface can be reversibly changed from superhydrophobicity to hydrophilicity by alternation of ultraviolet (UV) irradiation and dark storage.

Hydrophobic and Hydrophilic Interactions↗
PubMed2000

Micromorphological investigation of noncarious cervical lesions treated with demineralizing agents.

PURPOSE: The purpose of this study was to examine the micromorphology of noncarious cervical lesions (NCCL) and the change occurring after acid conditioning. MATERIALS AND METHODS: Nine wedge-shaped lesions, 9 saucer-shaped lesions, and 5 third molars with prepared cervical cavities were used. All NCCLs exhibited a hard, smooth surface with no discoloration. The teeth were sectioned and divided into three groups, each containing the three lesion types. Teeth in Group I were not etched, and teeth in Groups II and III were etched with 35% phosphoric acid and 20% polyacrylic acid/3% aluminum chloride, respectively. Field emission SEM and atomic force microscopy were used to examine the lesion surfaces. RESULTS: The surfaces of the prepared cervical (control) lesions were covered with a smear layer. Treatment with phosphoric acid and polyacrylic acid resulted in removal of the smear layer, although some residual smear layer was found on the surface treated with polyacrylic acid. The images of the untreated surfaces of NCCL showed highly mineralized dentin with complete obliteration of the dentinal tubules. After treatment with phosphoric and polyacrylic acids, the images revealed demineralization of the surface, which was more pronounced on those treated with phosphoric acid. CONCLUSION: The mineral deposits on the surface of NCCL decreased the effect of acid conditioning. Although there was no apparent difference between the two forms of NCCL used in this study, further work is needed to better understand these lesions.

Acid Etching, Dental↗
PubMed1993

A double-blind evaluation of topical capsaicin in pruritic psoriasis.

BACKGROUND: Substance P, an undecapeptide neurotransmitter, has been implicated in the pathophysiology of psoriasis and pruritus. OBJECTIVE: Safety and efficacy of topical capsaicin, a potent substance P depletor, were evaluated in patients with pruritic psoriasis. METHODS: Patients applied capsaicin 0.025% cream (n = 98) or vehicle (n = 99) four times a day for 6 weeks in this double-blind study. Efficacy was based on a physician's global evaluation and a combined psoriasis severity score including scaling, thickness, erythema, and pruritus. RESULTS: Capsaicin-treated patients demonstrated significantly greater improvement in global evaluation (p = 0.024 after 4 weeks and p = 0.030 after 6 weeks) and in pruritus relief (p = 0.002 and p = 0.060, respectively), as well as a significantly greater reduction in combined psoriasis severity scores (p = 0.030 and p = 0.036, respectively). The most frequently reported side effect in both treatment groups was a transient burning sensation at application sites. CONCLUSION: Topically applied capsaicin effectively treats pruritic psoriasis, a finding that supports a role for substance P in this disorder.

Administration, Topical↗
PubMed1992

Tretinoin emollient cream: a new therapy for photodamaged skin.

BACKGROUND: Tretinoin administered topically in 0.1% concentration has been shown to improve the wrinkling and irregular pigmentation of photoaged skin. OBJECTIVE: The purpose of this study was to assess the safety and efficacy of various concentrations of tretinoin in a new emollient cream base in the treatment of photoaged skin. METHODS: Three concentrations of tretinoin (0.05%, 0.01%, and 0.001%) in a new emollient cream formulation were compared with vehicle in a 24-week, double-blind, randomized, multicenter study of 296 subjects with photodamaged facial skin. RESULTS: Tretinoin emollient cream 0.05% gave a significantly better global response to therapy than vehicle (p less than 0.001), with 68% of subjects exhibiting improvement at the end of therapy, compared with 43% of subjects in the vehicle group. An excellent or good response was found in 26% of subjects treated with tretinoin emollient cream 0.05% versus 11% of vehicle-treated subjects. Fine wrinkling, mottled hyperpigmentation, and roughness were more improved in subjects who received tretinoin emollient cream 0.05% than in vehicle-treated subjects (p less than 0.05). No significant difference was found between vehicle and tretinoin emollient cream 0.01% or 0.001%. Histologic examination showed increases in epidermal and granular layer thickness, decreased melanin content and compaction of the stratum corneum after therapy with tretinoin emollient cream 0.05% or 0.01%. Mild to moderate skin reactions, such as erythema, peeling, and burning, were the most common side effects and, although most prevalent in the group using the 0.05% concentration, generally did not limit tretinoin use. CONCLUSION: Tretinoin emollient cream 0.05% appears to be safe and effective in the treatment of photodamaged skin.

Administration, Topical↗
PubMed1986

Interferon therapy for condylomata acuminata.

Current therapy for condylomata acuminata (genital warts) is not consistently effective. Therefore, we conducted a randomized, double-blind trial to compare interferon alpha-2b with placebo in the treatment of this disorder. Our rationale was that interferon has both antiproliferative and antiviral properties. The placebo or interferon (1 X 10(6) IU) was injected directly into one to three warts three times weekly for three weeks. The injections were well tolerated by both groups of patients. The side effects of fever, chills, myalgia, headache, fatigue, and leukopenia occurred more commonly in the interferon group than in the placebo group, but such effects rarely disrupted daily routines. Only 13 of 296 patients (4 percent) discontinued therapy because of side effects (11 in the interferon group and 2 in the placebo group). Twenty-six other patients were excluded from analysis because of a loss to follow-up or other deviations from protocol, thus leaving 257 patients in the final evaluation. At one week after the completion of therapy, interferon had produced a large and significantly greater reduction in mean wart area (a 62.4 percent decrease), as compared with placebo (a 1.2 percent increase in mean area) (P less than 0.001). At the conclusion of the study (13 weeks after the completion of therapy), the mean wart area was still decreased 39.9 percent below the initial size in the interferon group, whereas it had increased by 46 percent over base-line measurements in the placebo group (P less than 0.001). At the same time, all treated warts had completely cleared in 36 percent of the interferon recipients and in 17 percent of the placebo recipients (P less than 0.001), whereas treated warts progressed in 13 percent of the interferon recipients and in 50 percent of the placebo recipients (P less than 0.001). We conclude that injection of interferon alpha-2b directly into genital warts appears to be an effective and fairly well-tolerated form of therapy.

Adolescent↗