In the coming decade, the ability to sense and detect the state of biological systems and living organisms optically, electrically and magnetically will be radically transformed by developments in materials physics and chemistry. The emerging ability to control the patterns of matter on the nanometer length scale can be expected to lead to entirely new types of biological sensors. These new systems will be capable of sensing at the single-molecule level in living cells, and capable of parallel integration for detection of multiple signals, enabling a diversity of simultaneous experiments, as well as better crosschecks and controls.

/pdf/the-use-of-nanocrystals-in-biological-detection-3f8dgrg9fx.pdf

The use of nanocrystals in biological detection

Millions of years before we began to manipulate the flow of light using synthetic structures, biological systems were using nanometre-scale architectures to produce striking optical effects. An astonishing variety of natural photonic structures exists: a species of Brittlestar uses photonic elements composed of calcite to collect light, Morpho butterflies use multiple layers of cuticle and air to produce their striking blue colour and some insects use arrays of elements, known as nipple arrays, to reduce reflectivity in their compound eyes. Natural photonic structures are providing inspiration for technological applications.

Photonic structures in biology

Reproductive Biology of Invertebrates

Cubic boron nitride (cBN) has a number of highly desirable mechanical, thermal, electrical, and optical properties. Because of this, there has been an extensive worldwide effort to synthesize thin films of cBN. Film synthesis is difficult in that without significant levels of ion bombardment during growth, only sp2-bonded BN forms, not sp3-bonded cBN. Recently there has been considerable progress in improving the deposition techniques and cBN film quality. In addition, progress has been made in understanding how energetic deposition conditions can lead to cBN formation. However, unanswered questions remain and process improvements are still needed. In this paper we critically and comprehensively review recent developments in cBN film synthesis and characterization. First, the structures and stability of the BN phases and characterization techniques are described. Next, the key experimental parameters controlling cBN film formation and synthesis techniques are discussed. Following a review of microstructure, the proposed mechanisms of cBN formation and the observed mechanical and electrical properties of cBN films are analyzed. We conclude by highlighting the current impediments to the practical realization of cBN-film technology.

/pdf/review-of-advances-in-cubic-boron-nitride-film-synthesis-29xsb46ct5.pdf

Review of advances in cubic boron nitride film synthesis

In women, endometrial morphology and function undergo characteristic changes every menstrual cycle. These changes are crucial for perpetuation of the species and are orchestrated to prepare the endometrium for implantation of a conceptus. In the absence of pregnancy, the human endometrium is sloughed off at menstruation over a period of a few days. Tissue repair, growth, angiogenesis, differentiation, and receptivity ensue to prepare the endometrium for implantation in the next cycle. Ovarian sex steroids through interaction with different cognate nuclear receptors regulate the expression of a cascade of local factors within the endometrium that act in an autocrine/paracrine and even intracrine manner. Such interactions initiate complex events within the endometrium that are crucial for implantation and, in the absence thereof, normal menstruation. A clearer understanding of regulation of normal endometrial function will provide an insight into causes of menstrual dysfunction such as menorrhagia (heavy menstrual bleeding) and dysmenorrhea (painful periods). The molecular pathways that precipitate these pathologies remain largely undefined. Future research efforts to provide greater insight into these pathways will lead to the development of novel drugs that would target identified aberrations in expression and/or of local uterine factors that are crucial for normal endometrial function.

/pdf/endocrine-regulation-of-menstruation-2jsj6iqvat.pdf

Endocrine regulation of menstruation.

Electron tomography and computer visualisation of a three-dimensional 'photonic' crystal in a butterfly wing-scale.

Long-acting progestogenic contraceptives are frequently associated with disturbances of menstrual bleeding patterns. In particular, irregular, frequent and prolonged bleeding are commonly seen. The mechanism of this irregular bleeding is unknown, but changes in the endometrial vasculature are thought to be of importance. In endometrial biopsies from Norplant users, an increase in endometrial microvascular density has been observed after 3-12 months. Morphological changes in endometrial capillaries following progestogen exposure have suggested an increase in vascular fragility. Little is known about the structure and function of the endometrial vasculature in vivo following exposure to exogenous contraceptive steroids. This study has developed techniques for the assessment of vascular fragility by imposing a mechanical stress on the endometrium and observing subsequent bleeding under direct vision. The techniques were used in a preliminary examination between 1 and 9 months after Norplant insertion, and the study identified a number of morphological and functional characteristics of Norplant-exposed endometrium.

/pdf/endometrial-vasculature-in-norplant-users-preliminary-ureo9jl0bd.pdf

Endometrial vasculature in Norplant® users: preliminary results from a hysteroscopic study

The aim of this study was to develop an objective test for superficial endometrial vascular fragility at hysteroscopy and to apply this test to women using Norplant® for contraception and to women with ovulatory dysfunctional uterine bleeding (DUB). A prospective observational study was carried out in 34 Norplant users and 20 women with menorrhagia due to ovulatory DUB. Superficial endometrial vascular fragility was assessed at hysteroscopy by observing the source and extent of frank and subepithelial bleeding during controlled collapse and redistension of the uterine cavity. Superficial endometrial blood vessels were more fragile in Norplant users compared to women with DUB (?(2) = 11.60 P = 0.02). Superficial endometrial petechine (?(2) = 37.9 P < 0.0001) and ecchymoses (?(2) = 42.2 P = 0.0001) were more frequently observed in the Norplant users than in the menorrhagia group. In Norplant users superficial endometrial vascular fragility was increased in those with frequent bleeding or spotting during the past 30 days (?(2) = 6.15 P = 0.01) and in those who were examined during a bleeding episode (?(2) = 5.3 P = 0.02). Fragility was increased in the menorrhagia group during the perimenstrual period (days 24 to 05; ?(2) = 12.83 P = 0.01). There was no obvious relationship between subepithelial bleeding and circulating concentrations of oestradiol and progesterone. (authors)

Superficial endometrial vascular fragility in Norplant users and in women with ovulatory dysfunctional uterine bleeding

Porous scaffolds with tailored reactivity modulate in-vitro osteoblast responses

The use of progestogens without oestrogen is commonly associated with irregular menstrual bleeding. Oestrogens and progestogens are both thought to influence endometrial perfusion; changes in endometrial perfusion may contribute to vascular fragility and breakdown. In this study, endometrial perfusion was measured using laser-Doppler fluxmetry in women in the secretory phase of the menstrual cycle before and 4-6 weeks after insertion of the low-dose long-acting levonorgestrel contraceptive implant system, Norplant. Endometrial perfusion was also measured in women exposed to Norplant for up to 19 months. There was no significant difference between endometrial perfusion in control cycles (27.2 flux units +/- 5.5, SEM) and at 4-6 weeks after Norplant insertion (16.3 flux units +/- 5.0), a time when irregular bleeding and spotting are common. Endometrial perfusion was no different from controls after longer periods of Norplant exposure (35.7 flux units +/- 7.2). No direct relationships between endometrial perfusion and plasma concentrations of ovarian steroid hormones were demonstrated. Short-term endometrial vasomotion was largely abolished during Norplant exposure.

D. M. Dwarte

Papers

Electron tomography and computer visualisation of a three-dimensional 'photonic' crystal in a butterfly wing-scale.

Endometrial vasculature in Norplant® users: preliminary results from a hysteroscopic study

Superficial endometrial vascular fragility in Norplant users and in women with ovulatory dysfunctional uterine bleeding

Porous scaffolds with tailored reactivity modulate in-vitro osteoblast responses

The measurement of endometrial perfusion in Norplant users: a pilot study