Evolution of methane density during melting in nanopores.

Phase properties of gases adsorbed in small nanopores are mainly determined by the pore size and shape as well as the structural heterogeneity of the adsorbate. Here we analyze the evolution of the melting mechanism that occurs in pores <3 nm in size. Melting in slit-shaped graphene pores is compared with melting in SURMOF channel pores with square cross-sections. We show how the melting transformation is related to the adsorption mechanism. We use a graphical representation of the evolution of molecular density as a function of temperature in the nanopores.

Heterogeneous melting of methane confined in nano-pores.

The melting transition of methane adsorbed in nanopores has been studied and compared in two types of structures: carbon slits pores and square shaped channels. We show that the nano-confinement not only modifies the temperatures of phase transformation but also induces strong space heterogeneity of the adsorbate. We emphasize the role of the structural heterogeneity on the mechanism of melting: in nanometric pores, each adsorbed layer exhibits different mechanisms of structural transformation and the notion of a unique transition temperature is not well defined.

Nanospace engineering of KOH activated carbon.

This paper demonstrates that nanospace engineering of KOH activated carbon is possible by controlling the degree of carbon consumption and metallic potassium intercalation into the carbon lattice during the activation process. High specific surface areas, porosities, sub-nanometer (<1 nm) and supra-nanometer (1-5 nm) pore volumes are quantitatively controlled by a combination of KOH concentration and activation temperature. The process typically leads to a bimodal pore size distribution, with a large, approximately constant number of sub-nanometer pores and a variable number of supra-nanometer pores. We show how to control the number of supra-nanometer pores in a manner not achieved previously by chemical activation. The chemical mechanism underlying this control is studied by following the evolution of elemental composition, specific surface area, porosity, and pore size distribution during KOH activation and preceding H(3)PO(4) activation. The oxygen, nitrogen, and hydrogen contents decrease during successive activation steps, creating a nanoporous carbon network with a porosity and surface area controllable for various applications, including gas storage. The formation of tunable sub-nanometer and supra-nanometer pores is validated by sub-critical nitrogen adsorption. Surface functional groups of KOH activated carbon are studied by microscopic infrared spectroscopy.

Melting of hexane monolayers adsorbed on graphite: the role of domains and defect formation.

We present the first large-scale molecular dynamics simulations of hexane on graphite that completely reproduce all experimental features of the melting transition. The canonical ensemble simulations required and used the most realistic model of the system: (i) a fully atomistic representation of hexane; (ii) an explicit site-by-site interaction with carbon atoms in graphite; (iii) the CHARMM force field with carefully chosen adjustable parameters of nonbonded interaction, and (iv) numerous >or=100 ns runs, requiring a total computation time of ca. 10 CPU years. The exhaustive studies have allowed us to determine the mechanism of the transition: proliferation of small domains through molecular reorientation within lamellae and without perturbation of the overall adsorbed film structure. At temperatures greater than that of melting, the system exhibits dynamically reorienting domains whose orientations reflect the graphite substrate's symmetry and whose size decrease with increasing temperature.

Thermographic assessment of craniomandibular disorders: diagnostic interpretation versus temperature measurement analysis.

This study assessed electronic thermography as a diagnostic alternative for evaluation of temporomandibular disorders. The study populations consisted of 50 temporomandibular joint patients having internal derangement or osteoarthrosis and 30 normal temporomandibular joint subjects. An Agema 870 thermovision unit was used for analysis. Diagnostic evaluations by expert interpreters were made using standard procedures. Thermography measurements included mean absolute temperature measurements and right-left temperature differences for five anatomic zones and four spot areas. Statistical analysis of data included both linear discriminant analysis and classification-tree analysis. Results indicated that when differentiating between "abnormal" and "normal" temporomandibular joints using classification-tree analysis, correct classifications were made in 89% of the cases and observer diagnostic accuracy was 84%. When evaluating for specific diagnoses (eg, osteoarthrosis, internal derangement, or normal temporomandibular joint), correct classifications using classification-tree analysis were made in 73% of the cases and observer evaluation was correct in 59%. The three best temperature measures found were: (1) delta T of the zone immediately overlying the temporomandibular joint; (2) the zone temperature of the half-face; and (3) the spot temperature anterior to the external auditory meatus. Additional studies are needed before thermographic diagnosis of craniomandibular disorders is accepted clinically.

Thermographic characterization of internal derangement of the temporomandibular joint.

This study assessed the ability of electronic thermography to identify internal derangement of the temporomandibular joint. The study population consisted of 30 patients with internal derangement verified by temporomandibular joint arthrotomography. Electronic thermography was conducted using an Agema 870 thermographic unit. Thermal assessments included: (1) pattern recognition; (2) pattern symmetry; (3) absolute temperature measurements; (4) delta T measurements; and (5) mean temperature measurements and differences within five designated anatomic zones. Results indicated: (1) low levels of thermal symmetry in patients with internal derangement of the temporomandibular joint, and (2) absolute temperature measurements and mean temperature zone measurements showing large delta T values (0.4 degrees C to 0.8 degrees C). Demonstration of characteristic thermal temporomandibular joint changes suggests that electronic thermography may have potential for assessing internal derangement of the temporomandibular joint. However, more extensive studies are needed before thermographic procedures can be accepted clinically.

Thermographic characterization of osteoarthrosis of the temporomandibular joint.

This study assessed the use of electronic thermography in the thermal image characterization of 20 patients with osteoarthrosis of the temporomandibular joint as proven by radiographic detection of bone erosions. Thermal assessments included: pattern recognition, pattern symmetry, absolute temperature, delta T measurements, and mean temperature measurements and differences within five designated anatomic zones. In patients with osteoarthrosis of the temporomandibular joint, results demonstrated some characteristically abnormal thermal patterns; low levels of thermal symmetry; and substantially elevated absolute temperature measurements, mean temperature zone measurements, and delta T values. These observations suggest that electronic thermography may prove to be clinically useful as a diagnostic method of assessing temporomandibular joint disorders, particularly osteoarthrosis. However, more extensive studies are needed before thermographic evaluation of the temporomandibular joint will be accepted clinically.

Thermographic observations in unilateral carpal tunnel syndrome: report of 61 cases.

This study was undertaken to assess the sensitivity and specificity of thermographic diagnosis of unilateral carpal tunnel syndrome in a patient population large enough to permit meaningful statistical analysis. Sixty-one persons with clinical diagnoses of unilateral carpal tunnel syndrome confirmed by electrodiagnostic examination and 40 symptom-free volunteers underwent standard thermographic examinations. The thermographic images were then randomly sorted and interpreted by an experienced physician thermographer. Fifty-seven of the 61 patients with carpal tunnel syndrome were found to have thermographic abnormalities, while only one of the control group was found to have such an abnormality. Individual area sensitivity was highest in the dorsal area, but addition of other regions increased this measure; specificity ranged between 98% and 100%. These findings would appear to confirm the value of thermography in the diagnosis of unilateral carpal tunnel syndrome.

Neuromuscular thermography of the lumbar spine with CT correlation.

Fifteen asymptomatic volunteers and 19 patients with current CT (GE 8800 CT/T) scans demonstrating either thecal sac contour distortion or nerve root displacement from disc rupture or spinal stenosis of the L4-L5 or L5-S1 levels judged to be at least moderate in severity underwent lumbar thermography. All patients were studied with an infrared telethermographic unit (AGA model 720M) employing the technical standards recommended by the Academy of Neuromuscular Thermography. The thermographic exams were interpreted independently and in a blind fashion by two radiologists. Of the 15 exams of asymptomatic patients, six were interpreted as positive and consistent with nerve fiber irritation. Of the 19 exams of patients with demonstrated CT abnormalities, all had positive thermograms for nerve fiber irritation (specificity 60%, sensitivity 100%). It is concluded that lumbar thermography is a sensitive examination for detecting those patients who will demonstrate lumbar spinal CT abnormalities and should play an important role in the diagnostic screening of low-back pain syndrome patients.

Minimum weight for onset of sexual maturity in female chickens: heritability and phenotypic and genetic correlations with early growth rate.

The heritability of minimum weight for onset of sexual maturity in chickens (WTSXM) and its phenotypic and genetic correlations with early growth rate were studied in a Leghorn (L) layer stock, in two White Rock (WR) broiler stocks, and in the F4, F5, and F6 segregating generations of a White Rock X Leghorn (WR X L) cross. Mean heritability of WTSXM was .38 in the WR populations and .84 in the WR X L cross populations. Mean WTSXM of the various genetic stocks were closely related to their mean early growth rate. The mean phenotypic correlation of WTSXM and early growth rate was .07 in the WR populations but .47 in the WR X L cross populations. Estimates of the genetic correlation of WTSXM with early growth rate were high, and uniform in sign in the WR X L cross populations but smaller in magnitude and variable in sign in the WR populations. The implications of these results with respect to WTSXM as a breeding objective are discussed.

Liquid crystal thermography of the spine and extremities. Its value in the diagnosis of spinal root syndromes.

Cholesteric liquid crystals are special compounds that display specific color changes in response to variations in temperature. Their responses can be graphically demonstrated by means of color thermography. A new color contract thermographic technique is described utilizing liquid crystals embedded in elastic flexible sheaths. These sheaths, when inflated, conform to the varied contours of the torso and extremities and, therefore, the new thermographic technique is especially well suited to the study of the skin dermatomes and myotomes. Typical heat patterns have been observed in root compression syndromes and particularly at the S-1, L-5, L-4, C-6, C-7, and C-8 levels. A high degree of anatomic accuracy can thus be achieved, comparable to or better than can be achieved by electromyography or myelography. Liquid crystal thermography can serve to screen patients for myelography and can complement myelography in identifying clinically significant abnormalities. The imaging technique correlates well with clinical and surgical findings, and constitutes one of the first attempts by means of a concomitant study of the body dermatomes to objectively document the subjective complaint of pain.