Large-scale continuous hydrothermal production and activation of ZIF-8.

A new method for the large-scale hydrothermal production and activation of ZIF-8 is presented in this communication. Activated ZIF-8 has been produced, at lab-scale and pilot-scale, at a rate of 27 g h(-1) and 810 g h(-1) respectively with the activated material showing a surface area of 1800 m(2) g(-1).

Complications of cutaneous laser surgery. A survey.

We surveyed a selected group of 139 dermatologists and plastic surgeons about their experience with the complications of cutaneous laser surgery. Reported complication rates varied from 0% to 35%, with means of 3.2% for dermatologists and 6.2% for plastic surgeons using the argon laser, and 4.2% for dermatologists and 2.8% for plastic surgeons using the carbon dioxide laser. Hypertrophic scarring was the complication noted most frequently; 69% of physicians using the argon laser and 64% of physicians using the carbon dioxide laser have seen at least one case of hypertrophic scarring. Complications noted less frequently include infection, pain, atrophic scarring, intraoperative or postoperative hemorrhage, and prolonged wound healing. Environmental accidents were few. No procedure-related deaths, ocular damage, or secondary cutaneous malignant neoplasms were reported. We conclude that cutaneous laser surgery has an acceptable risk profile but that complications are not uncommon.

Contribution of topical tar oil to ultraviolet B phototherapy for psoriasis.

A bilateral comparison study of twenty-two outpatients with psoriasis assessed clearing experience and remission time on halves of the body to which tar oil and oil vehicle (an emollient) were applied twice daily. In addition, both sides were treated three times a week with suberythemogenic doses of ultraviolet B radiation. Of the eighteen patients who complied with the protocol, fourteen (78%) had clearing. There was no significant difference between body halves with regard to the number of treatments to clearing, the dose of ultraviolet B to clearing, or the remission time (p greater than 0.2, all comparisons). Our data indicate with 95% confidence that using tar oil in conjunction with ultraviolet B phototherapy reduces the average total ultraviolet B dose required for clearing by a maximum of 9%, in comparison with using oil vehicle and ultraviolet B. These findings suggest that there is insufficient evidence for substantial clinical benefit to recommend tar oil use in conjunction with outpatient ultraviolet B phototherapy for psoriasis.

Low-fluence CO2 laser irradiation: selective epidermal damage to human skin.

The interaction of normal human skin with low-fluence CO2 laser irradiation was studied using a three-phase approach. In phase one, freshly excised skin was observed immediately after impact. In phase two, skin irradiated 2 h prior to excision was studied. In phase three, human volunteers were irradiated and biopsied at time zero, 24 h and 48 h. Seventy-five sites were exposed and 60 biopsies were performed. The earliest histologic changes were observed in the 6-10 J/cm2 fluence (radiant exposure) range and these changes included spindle and vacuolar changes in the basal layer of the epidermis. Papillary dermal coagulation was present to a maximum of 0.03 mm. At fluences of 10-25 J/cm2, superficial dermal necrosis (0.06-0.08 mm) was observed. At fluences above 25 J/cm2, transepidermal necrosis was present with increasing papillary dermal necrosis that was in proportion to the energy density delivered. At 2h, basal vacuolar changes were accompanied by diffuse keratinocytic cell death where contact was maintained between the epidermis and dermis, while where separation occurred limited keratinocytic death was observed. The earliest changes occurred at lower threshold fluences (4-6 J/cm2). After 24 h, these doses resulted in extensive epidermal necrosis with focal acute inflammatory infiltrates. At 48 h, the degree of epidermal "slough" was proportional to the energy density delivered and was maximal with a fluence of 5.7 J/cm2 delivered whereas with a fluence of 3.8 J/cm2 thin slough (0.02 mm) was observed. These findings suggest that low-dose CO2 laser irradiation may provide a new approach to selectively damage the epidermis with minimal dermal damage.

In vivo spectrophotometric evaluation of normal, lesional, and laser-treated skin in patients with port-wine stains.

The influence of patient age and argon laser therapy on port-wine stains (PWS) was studied quantitatively in 16 patients aged 15-64 years using a spectrophotometer and computer graphics/statistics program. Normalized reflectance curves revealed a 10-20% decrease with age in the reflectance of normal skin from 400 nm to 650 nm, with an even more pronounced reflectance decrease in the region of peak deoxyhemoglobin absorption at approximately 555 nm. In each patient, PWS reflectance was less than that in the normal skin, as expected, and the average discrepancy increased with age from approximately 25% to 50%, with further reduction at 555 nm. The data suggest that with advancing age, both normal skin and PWS have a greater total hemoglobin content and an increased proportion of deoxyhemoglobin, consistent with increasing vascular dilation and tortuosity; and that the age-associated changes in PWS are an exaggeration of those in normal skin. Laser-treated PWS in both young and old patients had reflectance curves indistinguishable from those of untreated PWS in young patients. This implies, contrary to published clinical impressions, that in the absence of scarring the results of argon laser therapy are the same in young and old patients, but that only older patients experience a significant color shift in the lesion.