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The coronavirus, COVID-19 pandemic spread across the globe in 2020, with an initial high case mortality in those requiring intensive care treatment due to serious complication. A vaccine programme was quickly developed and currently the UK is one of highest double vaccinated and boosted countries in the world. Despite tremendous efforts by the UK, new cases of COVID-19 are still occurring, due to viral mutation. A major problem associated with COVID-19 is the large a-symptomatic spread within the population. Little investigation into the a-symptomatic population has been carried out and therefore we pose that the residual effects of a-symptomatic infection is still largely unknown. Prior to mass vaccination, a multi-phased single cohort study of IgM and IgG COVID-19 antibody prevalence and the associated haemostatic changes were assessed in a Welsh cohort of 739 participants, at three time points. Positive antibody participants with age and gender matched negative antibody controls were assessed at 0, 3 and 6 months. Antibody positive females appeared to have lower antibody responses in comparison to their a-symptomatic male counterparts. Despite this initial testing showed a unique significant increase in TRAP-6-induced platelet aggregation, prothrombin time (PT) and clot initiation time. Despite coagulation parameters beginning to return to normal at 3 months, significant decreases are observed in both haemoglobin and haematocrit levels. The production of extracellular vesicles (EV) was also determined in this study. Although the overall number of EV does not change throughout the study, at the initial 0 months' time point a significant increase in the percentage of circulating pro-coagulant platelet derived EV is seen, which does not appear to be related to the extent of platelet activation in the subject. We conclude that early, but reversible changes in haemostatic pathways within the a-symptomatic, female, antibody positive COVID-19 individuals are present. These changes may be key in identifying a period of pro-coagulative risk for a-symptomatic female patients.

Bacterial contamination of money acts as vehicle for the transmission of pathogenic and drug resistant organisms. This study was carried out to investigate the bacteriological quality and antibiotic susceptibility patterns of money bank cash-points and markets in Port Harcourt metropolis. Two hundred and eighty-eight (288) naira notes belonging to the following denominations, N5, N10, N20, N50, N100, N200, N500 and N1000 were collected for three months from banks and markets and subjected to standard microbiological procedures such as standard plate counts, identification, sensitivity testing using Kirby-Bauer disk diffusion method. Total heterotrophic bacterial count (THB) ranged from 0.6±0.00x106 to 12.80±9.19x106cfu/g; 0.65±0.21x106 to 13.05±9.55x106cfu/g; 0.65±0.20x106 to 8.05±2.48x106Cfu/g in N5 and N100 from Access Bank (AB), United Bank of Africa (UBA) and Guaranty Trust Bank (GTB), respectively. There was a significant difference (p≤0.05) in the THB between the different naira notes. Total coliform count (TCC) ranged from 0.00 x104 to 56.90±28.43x104Cfu/g; 0.00 x104 to 61.90±35.49x104Cfu/g; 0.00x104 to 17.75±12.79x104Cfu/g in N5, and N100 for AB, UBA and GTB respectively. THB ranged from 2.69±1.55x106 to 9.95±3.22x106cfu/g; 3.00±1.69x106 to 12.30±9.89x106cfu/g; 3.30±1.82x106 to 17.30±6.97x106cfu/g in N1000, N10 and N100 naira for Mile 1, Mile 3 and Creek road markets respectively. There was a significant difference (p≤0.05) in the THB between the different naira notes sampled in both Banks and markets. TCC ranged from 0.77±0.28x104 to 45.59±10.18x104Cfu/g; 0.78±0.88x104 to 40.59±3.11x104Cfu/g; 1.45±0.07x104 to 55.60±10.18x104Cfu/g in N1000 and N100 Mile 1, Mile 3 and Creek road market respectively. Faecal coliform count ranged from 0.00x103 to 1.53±0.15x103Cfu/g for only mile 1 market. There was a significant difference (p≤0.05) in the total and faecal coliform counts between the different naira notes sampled in Banks and markets. The bacterial isolates identified were; Escherichia coli, Staphylococcus aureus, Micrococcus luteus, Bacillus cereus and Serratia marcesens. Twenty-one (21) bacteria were isolated from Banks and Markets. Bacillus cereus, Staphylococcus aureus, Micrococcus leteus, Escherichia coli and Serratia marcesens were significantly high in N100 (41.67%) (66.67%), (100%), (100%) respectively. Staphylococcus spp was susceptible to Gentamicin (33.3%), Bacillus spp to Ofloxacin (100%), Micrococcus spp to Ofloxacin and Gentamicin (100%), Serratia spp and Escherichia coli were susceptible to Ofloxacin, Gentamicin and Nitrofurantoin (100%) and they were all resistant to Ceftazidime, Cefixime, Cloxacillin, Augmentin, Cefuroxime and Ceftriaxone (100%)> Erythromycin and Gentamicin (75%). Hundred-percent (100%) of the bacterial isolates had multidrug resistance index greater than 0.2. Public awareness on personal hygiene should be encouraged while drug abuse should be discouraged.

The formation of fungal biofilm in drinking water storage containers has not been giving considerable attention over the years despite the challenges posed by bacterial biofilms. Hence, the study aimed to determine the fungal occurrence and the associated biofilm formation capacity from domestic drinking water storage containers in Diobu homes of Port Harcourt. Fifty water samples were obtained from domestic storage containers in different house units, and the sample was subjected to the standard microbiological procedure. The spread and streak techniques were applied on antibiotics treated Saboraud Dextrose and Congo red growth media. The results shows that the mean fungi count of 6.2 x 102 and 6.1 x 102 CFU/ml in household sizes of 4 and 5 persons respectively were less than that of the household population of 2, 6, and 8 persons with the fungal count of 8.7x102, 8.3x102 and 8.0x102CFU/ml respectively. Positive, negative and zero relationships were established between the household sizes and the fungal recovered. The analysis further revealed a total of 25 fungal isolates of which three genera were distinguished morphologically, namely, Aspergillus flavus, Candida albicans and Penicillium notatum. All isolates were able to form a heavy mass of biofilm; except Candida albicans which had a delayed formation after 24hours with less biofilm development potential, and thus signifies its inability to persist, despite having the highest count or load. The success of fungi biofilm is based on the constant growth rate of Aspergillus flavus and Penicillium notatum biofilms for which, the household size has reasonably be attributed. The study recommends that storage facilities in the homes be regularly cleaned and always disinfected to inhibit the successes of fungal biofilm.

Crude oil exploration has been beneficial to our economy but detrimental to our environment with the artisanal refineries further compounding the challenge. This research was aimed at investigating the microbiology and heavy metal pollution of three crude oil polluted rivers in Rivers State, Nigeria and effects on living organisms inhabiting that environment. This study was carried out in three locations in South-South Nigeria (Eagle Island, Iwofe and Chokocho rivers). A total of 64 water samples (upstream and downstream points) were collected using appropriate containers and sterile polyethene bags for 6 crab samples for a period of three months. Water and crab samples were analyzed for heavy metals using Atomic Absorption Spectrophotometric method while microbiological analysis involved isolation and enumeration of microbial populations of the water and crab samples as well as characterization and identification of the isolates using standard methods Results showed Total Heterotrophic bacteria (THB) ranged from 6.0 × 106 cfu/ml to 9.0 × 108cfu/ml for the downstream locations and 1.7 × 106cfu/ml to 3.5 × 107cfu/ml for the upstream locations. Total Heterotrophic Fungi (THF) ranged from 2.0 × 104cfu/ml to 1.1 × 105cfu/ml for downstream locations and 0.1 × 104cfu/ml to 4.0 × 104cfu/ml for upstream locations, Hydrocarbon Utilizing Bacteria (HUB) ranged from 0.8 × 103cfu/ml to 4.0 × 103cfu/ml in downstream locations and 2.0 × 103cfu/ml to 7.4 × 103cfu/ml in upstream locations, Hydrocarbon Utilizing Fungi (HUF) ranged from 1.0 × 103cfu/ml to 6.0 × 103cfu/ml for downstream locations and 5.0 × 102cfu/ml to 8.0 × 103cfu/ml for upstream locations. The bacteria identified biochemically included Serratia sp., Enterobacter sp. and Salmonella sp. for the crab samples and Bacillus sp. was dominant in the water samples (Bacillus subtilis, Bacillus cereus, Bacillus carboniphilus). The heavy metals (Fe, Ni, Zn, Cd, Cu, Mn, Cr and Pb) were below the DPR permissible limit but are likely to increase since the activities leading to pollution are still ongoing. The crab as a filter feeder, had higher concentration of heavy metals and microbial population and the location with the highest crude oil pollution (14.5mg/l) had the lowest THB (6.0 × 106cfu/ml) as physicochemical parameters like the amount of Dissolved Oxygen had been altered.

Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV), and Hepatitis C Virus (HCV) are all blood borne pathogens that are still global health challenges and were known to be endemic in Nigeria. Little work had been done on Hepatitis-B and C co-infection among HIV positive patients in the three Senatorial Districts of Rivers State. A case- control, hospital- based study was conducted among subjects from Rivers state University Teaching Hospital (RSUTH), Zonal Hospital, Bori and Zonal Hospital, Ahoada to determine the prevalence of Hepatitis B and C co-infection in these areas. Three hundred and seventy-five subjects of (10-69 years) and both sexes were included in the study. A structured questionnaire was administered to obtain demographic parameters of the participants. The samples collected were screened and confirmed for hepatitis-B and C using standard techniques. The overall prevalence rates of HBV, HCV and HBV/HCV in this study are 4.5%, 2.1% and 0.8% respectively while the prevalence among HIV positive participants were; 4.6%, 2.8% and 1.1% respectively. Bori had the highest prevalence of HBV and HCV, (5.3% and 4.2%) while Ahoada had the highest prevalence of triple infection (2.1%). The prevalence of HIV/HBV, HIV/HCV and HIV/HBV/HCV infection was more among subjects within age range of 30-39 years (7.0%, 5.6% and 4.2%) and lowest within the age range of 20-29 years (2.3%, 0% and 0%). Conclusively, the research findings show that the prevalence of hepatitis B and C co-infection among HIV patients in these hospitals are high. Thus, every HIV positive patient should be screened and educated on the danger of co-infection for better management of the patient.

The Childhood Asperger Syndrome Test (CAST) is a parental questionnaire to screen for autism spectrum conditions. In this validation study, the CAST was distributed to 1925 children aged 5-11 in mainstream Cambridgeshire schools. A sample of participants received a full diagnostic assessment, conducted blind to screen status. The sensitivity of the CAST, at a designated cut-point of 15, was 100 percent, the specificity was 97 percent and the positive predictive value was 50 percent, using the group’s consensus diagnosis as the gold standard. The accuracy indices varied with the case definition used. The sensitivity of the accuracy statistics to case definition and to missing data was explored. The CAST is useful as a screening test for autism spectrum conditions in epidemiological research. There is not currently enough evidence to recommend the use of the CAST as a screening test within a public health screening programme in the general population.

Plasma jets have been produced by the pulsed laser ablation of bulk ZnSe targets. Electrical measurements show that a sudden increase in ion yield occurs at a threshold pulse energy density of 210 mJ cm−2 pulse−1. The plasmas obtained do not exhibit overall electrical neutrality, but have a net positive charge, while the ZnSe target develops a corresponding negative charge. The initial ion translational kinetic energies are also found to be very low

Metal-organic chemical vapor deposition (MOCVD) can now be used routinely for the preparation of a wide variety of groups III-V semiconductor materials. Ga- and In-based binary (e.g., GaAs, InP), ternary (e.g., In(x)Ga(1-x)As), and quaternary (e.g., In(x)Ga(1-x)P(y)As(1-y) compounds may be prepared as epitaxial layers ranging in thickness from a few angstroms to several microns for device applications. However, an understanding of the chemistry involved in the gas phase and at growing surfaces during MOCVD is at a primitive level despite the progress of the past few years. In this account we shall review recent progress in the use of organometallic precursors for MOCVD. The purity of these starting materials will be considered in relation to the quality of resulting epitaxial layers. Reaction mechanisms involved in their decomposition and reactivity both in the gas phase and at substrate surfaces will be discussed. Carbon incorporation is comprehensively covered, and growth using alternative group III and group V precursors together with the decomposition reactivity of these reagents is reviewed. The prospects for chemists in this research field are excellent, and in our opinion they are essential to its further development and extension into hitherto unexplored territories.

Despite the rapid growth of laparoscopic cholecystectomy, the comparative costs of this new procedure and open cholecystectomy remain unknown. In this study the costs have been evaluated of a consecutive series of patients undergoing these procedures in a district general hospital with an established resource management centre. Fifty consecutive patients undergoing open cholecystectomy between June 1988 and July 1990 immediately before the introduction of laparoscopic cholecystectomy and 100 patients undergoing laparoscopic cholecystectomy between August 1990 and June 1992 were studied. Costs estimated prospectively for each patient were compared. The mean cost per patient of open cholecystectomy was estimated at £2102 compared with £2026 for the first 50 patients undergoing the laparoscopic procedure. The mean cost (£1744) for the second 50 patients undergoing laparoscopic cholecystectomy was less than that for either open cholecystectomy (P<

This report compare demographic characteristics of HRA taker and nontakers, and describes respondents who skipped potentially sensitive items as well as those reporting extreme values for certain health behaviors.

A total of 675,626 active duty Army soldiers who were known to be at risk for deployment to the Persian Gulf were followed from 1980 through the Persian Gulf War. Hospitalization histories for the entire cohort and Health Risk Appraisal surveys for a subset of 374 soldiers were used to evaluate prewar distress, health, and behaviors. Deployers were less likely to have had any prewar hospitalizations or hospitalization for a condition commonly reported among Gulf War veterans or to report experiences of depression/suicidal ideation. Deployers reported greater satisfaction with life and relationships but displayed greater tendencies toward risk-taking, such as drunk driving, speeding, and failure to wear safety belts. Deployed veterans were more likely to receive hazardous duty pay and to be hospitalized for an injury than nondeployed Gulf War-era veterans. If distress is a predictor of postwar morbidity, it is likely attributable to experiences occurring during or after the war and not related to prewar exposures or health status. Postwar excess injury risk may be explained in part by a propensity for greater risk-taking, which was evident before and persisted throughout the war.

AIMS: To establish criteria for the information to be included in a necropsy report, and to improve the quality of necropsy reporting in the Anglia Region. METHODS: Discussion between Anglia histopathologists, based on the guidelines of the Royal College of Pathologists, led to a consensus about the ideal content of a necropsy report. Fifteen consecutive necropsies subsequently undertaken by each consultant were assessed against agreed standards. Reaudit was undertaken nearly two years later, without prior announcement. RESULTS: The initial standards achieved for demographic details (70%), history (87%), external examination (43-97%), internal examination (76-95%), organ weights (73%), cause of death in OPCS format (94%), and conclusion (90%) were discussed by the group. Changes to necropsy reporting documentation were proposed. Reaudit showed improvement in nearly all categories. CONCLUSIONS: Necropsy reporting in East Anglia is currently carried out to a reasonably high standard, and improvements have occurred as a result of the audit. There was no evidence that reports on coroners9 necropsies were of a lower standard than those done for the hospital. Improvement in the format of the documentation increases the likelihood that all relevant and important data are recorded.

AIM: To examine current practice and to establish criteria for the use of histopathology in necropsy practice. METHODS: During an audit of necropsy reporting, consensus could not be reached about the use of routine histopathology. Therefore local guidelines were formulated and current practice was compared with these guidelines. Fifteen consecutive necropsies undertaken by each consultant were reviewed and the use of histopathology noted. RESULTS: In general, the standard of necropsy reporting was reasonably high. Tissue was retained for histopathology in 25% of necropsies and 72% of these necropsy reports included a histopathology report. Using the guidelines, the assessors judged that histopathology might have been valuable in a further 19%. It was felt that routine histopathology would not have been helpful in determining the cause of death in the remaining 56%. The importance of the pathologist's clinical judgement in individual cases was stressed. At reaudit, nearly two years later, there was no significant change in practice, reflecting the lack of consensus. CONCLUSIONS: Even when histopathology might contribute to finding the cause of death, it was not always done. However, the assumption that histology is invariably helpful in determining the cause of death is challenged.

The field of semiconductor devices has been transformed in recent years by the availability of preparative techniques capable of routinely providing materials in thin-film form and of extremely high purity. With advances in the field of metalorganic vapor phase epitaxy (MOVPE), molecular beam epitaxy (MBE), and metalorganic molecular beam epitaxy (MOMBE) has come the need to characterize materials using methods with higher sensitivities and much improved spacial resolution. It is no exaggeration to say that single atoms need to be seen and their influences recorded. These requirements have placed additional demands on characterization techniques. Table 1 summarizes a selection of the important techniques currently available for the chemical, structural, optical, and electrical characterization of epitaxial materials. Most of these can only be used to determine macroscopic (average) properties. Some, such as secondary ion mass spectrometry (SIMS) and the electrical techniques, can be combined with profiling to probe properties as a function of depth normal to the epitaxial layers, but at distances 10 ≲nm (100A) resolution limits begin to be approached.

The immune status of 100 Nigerian children (ages 0-14) from a paediatric hospital in Ibadan, against poliovirus, after the administration of polyvalent oral poliovirus vaccine (types 1, 2 and 3) was determined using serum neutralisation test. High antibody titres were demonstrated in 78% of all the age groups tested. 57% of children under two years of age, 75% of those three to five years, and 100% of those above six years, had high poliovirus antibodies. 77% of male (47 out of 61) and 79% of female (31 out of 39) were positive. The difference between the sexes is not statistically significant (P greater than 0.05).

A device which allows the continual passage of pulsed laser radiation into a photochemical deposition chamber without the need for a purge gas is described. The laser beam is loosely focused on the window surface to ablate any deposited material, which is then caught in an electrostatic trap to avoid contamination of the film growth.

The influence of temperature and humidity on the biology of insecticide-resistant and susceptible strains of Tribolium castaneum (Herbst) was studied and compared. At all temperatures (20, 25, 30 and 40°C) and r.h. (30, 50, 70, 90) tested, the insecticide-resistant strain matured earlier than the susceptible strain. For both strains, the lowest and highest temperature limits for embryonic development and egg hatching were 20 and 40°C, respectively. The incubation period for eggs of both strains averaged 14 days at 20°C and 4 days at 30°C. Females of the insecticide-resistant strain matured for egg laying earlier (24 hr) than the susceptible strain (60 hr) but laid fewer eggs (36 eggs) than the latter strain (238 eggs). At 30°C and 70% r.h. the resistant strain had a shorter developmental period (15 days) than the susceptible strain (21 days). Temperature influenced the development of larvae of both strains of T. castaneum. Larvae of the susceptible strain did not develop at 20°C and 30% r.h., 20°C and 90% r.h. and 40°C and 30%. r.h., whereas larvae of the resistant strains did. The pupae of both strains developed at all the temperature and relative humidity regimens tested. Temperature and humidity of stored food would therefore, act together to influence the abundance of strains of T. castaneum and the two factors could be manipulated to suppress the population growth of this beetle on stored food. Nous avons etudie et compare’ l’influence de la temperature et de l’humidete sur la biologie des souches susceptibles et des souches qui resistant a’ l’insecticide. A fortes les temperatures teste’es (20, 25, 30, et 40°C) et a toutes les humidite’s relatives (30, 40, 70, 90), nous avons remarque que la souche que resiste a l’insecticide a muri plus fot que la souche susceptible pour les deux souches, les temperatures les plus basses et les plus hantes pour le developpement embryonnaire ebient de l’ordre de 20 et 40°C respectivement. La periode d’incubation ebit en moyenne de 14 jours a 20°C et de 4 jours a 30°C. Les femelles de la souche qui resiste a l’insecticide ont alfaint l’age de pondre un seuf plus tot (24 hr) que celles de la souche susceptible (60 hr) mais elles ont pondu moins d’oeufs (36 seufs que les dernieres (238 seufs) a 30°C et 70% r.h. La period de developpement des femelles de la souche qui resiste a l’insecticide (15 jours) etait moins courte que celle des femelles de la souche susceptible (21 jours). Nous avons renarque l’influence de la temperature sur le developpement des larves des deux souches de T. castaneum. Les larves de la souche susceptibles ne se developpeaient pas a 20°C et 30% r.h., 20°C et 90% r.h. et 40° C et 30% r.h. alorz que les larves des souches resistantes s’y developpeaient. Les nymphes des deux souches ont temoigne du developpement al toutes les temperatures et humidites relatives testees. Donc, la temperature et l’humidite des vivres enmagasines agissent ensemble pour influer sur l’apondance des souches de T. castaneum, et les deux facteurs penvent etre manipules afin de supprimer la croissance de cet escarbot sur les vivres mis en magasin.

Anomalous ‘bent’ microtwins lying in a 〈111〉 direction and containing high concentrations of Ga and As have been observed in ZnSe epitaxial layers grown on (100)-oriented GaAs substrates by molecular beam epitaxy at 410°C. The bend radius R meas of 0·928 × 10−5 m compares favourably with a theoretical value based on the use of expressions applicable to a bimetallic strip comprised of GaAs and ZnSe.

The polarity or orientation of 〈110〉 projected single crystals of tetrahedral compound semiconductors has been determined by high-resolution electron microscopy (HREM) at 300 kV. The method has been applied to GaSb and computer simulations show that the image contrast is the reverse of that expected intuitively. Similar results are predicted for GaAs.

Twin boundaries found to occur in ZnSe epitaxial layers grown by metal-organic vapour phase epitaxy on {100} Ge substrates have been studied using high-resolution transmission electron microscopy. These twin boundaries are of the {111} type and, because of the polarity of the sphalerite (ZnSe) structure, can in principle exist as three different sub-types: neutral, P-type and N-type. Comparison of experimentally recorded images with extensive computer simulations of all three types of twin boundary show that while lattice images unique to each twin type can be found, it is possible to confuse the various types when the effects of crystal misorientation are considered. The present results, however, indicate that only the neutral type of twin boundary has been found so far in these epitaxial layers.

SUMMARY Selective photoelectrochemical etching has been employed in order to thin samples of ZnSe epilayers grown on GaAs (100) substrates by metal organic vapour phase epitaxy (MOVPE). The difference in band-gap between the epilayer and substrate was exploited such that only the substrate material was subject to the etching procedure. Samples prepared in this way have been studied by transmission electron microscopy (TEM) and the results of these studies are compared to results obtained by alternative cross-sectional analysis.

ZnSy Sel°y epitaxial layers have been deposited on GaAs substrates by hydrogen transport from elemental sources and employing hydrides as the source of Group VI elements. The dependence of the sulphur mole-fraction, y, on substrate temperature and reactant partial pressures was investigated. Under Zn-rich conditions y increased almost linearly with the H2S overpressure. Hall effect measurements indicated that the films were n-type with resistivity of 0.01 − 0.1Ω cm and high resolution electron microscopy indicated a sharp interface with low defect concentrations both at the interface and within the lattice-matched epitaxial layers.

Previous measurements by Kokado and Schneider have shown that the peak centred at ca. 0°C in the electrical conductivity-temperature plot is an intrinsic property of crystalline anthracene, its occurrence being attributed to the existence of discrete traps—believed to be structural imperfections—for positively charged carriers. This work reports the measurement of conductivity glow-curves in the range –70 to +15°C on vapour-grown, solution-grown, melt-grown, and deformed melt-grown crystals. It is demonstrated that, although a structural fault is probably responsible for the peak—only one peak is obtained with the high-purity material—non-basal dislocations introduced by deformation are not the principal cause for its occurrence. The magnitude of the glow peak, the position of which corresponds to the existence of trapping levels for positive holes 0.7 eV above the valence band, is decreased six-fold (from a value of 3 × 10–12 A) following a hundred-fold increase in the content of dislocations which glide on (100) and (20text-decoration:overline1) planes in the [010] direction. The significance of these results is discussed.

Dislocations in single crystals of melt-grown, solution-grown and vapour-grown anthracene have been characterized using the etch-pit technique and from an analysis of cleavage patterns. From the observed alignments of emergent dislocations (at (00l) faces) to form small-angle boundaries (of twist, tilt and mixed character), deductions are made concerning the planes and directions in which the dislocations move. The most widely occurring dislocations are those that glide in the (010) plane along the [001] direction. Dislocations that glide in the[100] direction in this plane are also feasible. Although less widely occurring, dislocations in the (100) plane exist, there being slight preference for those that glide along [010] to dominate, but those that move in the [001] direction definitely occur. The geometry of two kinds of emergent edge dislocations is outlined, and the relevance of lattice distortion at dislocation cores is considered in relation to the photodimerization of the solid.

The density of carrier traps situated within the entire energy gap of 3.7 eV in anthracene has been evaluated from current-voltage characteristics using the Mark and Helfrich equation, which is applicable to space-charge-limited-currents in organic crystals containing an exponential distribution of trap energies. A modified Kallman and Pope cell, consisting of aqueous iodide saturated with iodine as anode, was employed; and four kinds of anthracene crystal were studied. Trap densities range from 1013 cm–3, for vapour-grown samples, to 1019 cm–3, for deformed melt-grown samples; and there is strong evidence that positive holes are trapped at the immediate vicinity of the cores of non-basal dislocations. The apparent conflict between some of these results and those of the conductivity-glow measurements is discussed.

In all eight species of range grasses studied, the cellular architecture of the apex tip of the young aerial (vertical) shoots is subject to variation. In any given species, the range of cellular patterns encountered probably largely depends on the number of apices examined Parallel variations can be found from species to species. Similar alternatives of construction can be found in the rhizome apices, and there is nothing to distinguish their architecture from that of aerial shoots. The variations in apical structure of both rhizomes and aerial shoots are not plastochronic. The number of leaf primordia "carried" on the apex can vary considerably in both aerial shoots and rhizomes, even of the same species However, despite wide variation in actual numbers, on the average, rhizome apices appear to "carry" about one primordium fewer than aerial shoots. It is evident that the use of apical architecture as a basis for classification in the Gramineae needs considerable caution.

Dislocations in anthracene have been identified for the first time by diffraction contrast, transmission electron microscopy. Burgers vectors in the [010] direction are prominent.

Photoluminescence measurements at 2 K are described for Zn1-xMnxSe (x approximately=0.01) epitaxial layers grown by MOCVD on GaAs. The dominant feature is the I2 emission due to excitons bound at neutral donors (D0X). When magnetic fields of several tesla are applied, the emission shifts to lower energy and increases dramatically in intensity, in a way similar to that previously reported for Cd1-xMnxSe and Cd1-xMnxTe. The changes occur because the exchange enhancement of the magnetic field is sufficient for the lowest energy level of the free exciton to sweep across the D0X levels, so that the bound exciton becomes destabilised.

Metallisation and Related Reactions.- New Directions in LCVD Metallisation Introduction and Conclusion.- Photoinduced Organometallic Processes in Semiconductor Surface Technology.- U.V. Excimer Laser Induced Photochemistry of Gaseous Organometallics for Surface Modification.- Laser-Induced Photodissociation of Al2(CH3)6: Gas-phase and Adsorbed Layer Dissociation Mechanisms for Al Film Growth.- Photonucleation and Photodeposition of Al on Si from Flowing Trimethylaluminium in Hydrogen.- An in-situ Study of Chemical Vapour Deposition of Triisobutylaluminum on Si(100).- An in-situ Study of the U.V. Photochemistry of Adsorbed TiCl4, by FTIR Spectroscopy.- Model Studies of LCVD of Transition Metals on Silicon: Surface Processes.- Excimer Laser Assisted Deposition of Cr on B Films.- Reactions of Group V Metal Hydrides with Surfaces.- Techniques for Studying Silicon Deposition.- Some Considerations of the Kinetics and Thermodynamics of CVD Processes.- The Chemistry of Silicon Deposition from Hydride Decomposition.- The Spectroscopy of Crystal Growth Surface Intermediates on Silicon.- Growth of Semi-Conductors by Gas Phase Movpe.- Growth of Semi-Conductors by Thermal MOVPE Introduction and Conclusions.- Reactions in OMVPE Growth of GaAs Determined Using labelling experiments.- Chemical Boundary Layers (MOCVD): The Return of the Stagnant Layer.- Monitoring Chemical Reactions in Metal-Organic Chemical Vapour Deposition (MOCVD).- Surface Studies at Atmospheric Pressure and Under UHV Conditions During Growth of GaAs.- Gas Phase and Surface Effects in the Thermal Decomposition of AsH3 and PH3 Studies by CARS..- In Situ Raman Studies of AsH3, and TMG Thermal Decomposition in GaAs MOVPE Conditions.- Surface vs Gasphase Processes in the MOCVD of GaAs..- Multiphoton Ionisation/Mass Spectrometnc Study of OMCVD Mechanisms Under Single Gas-Surface Collision Conditions.- CVD of SiC and A1N Thin Films Using Designed Organometallic Precursors.- Anisotropic Growth of GaAs in MOVPE.- Selective and Nonplanar Metal Organic Vapour Phase Epitaxy.- Photochemical Movpe Growth of Compound Semi-Conductors.- and Conclusions.- Mechanisms of the Photochemical Growth of Cadmium Mercury Telluride.- Alternative Growth Techniques to Atmospheric Pressure Movpe.- and Conclusions.- The Role of Surface and Gas Phase Reactions in Atomic Layer Epitaxy.- Gas Source Molecular Beam Epitaxy.- Heteroepitaxy of InSb by Metal Organic Magnetron Sputtering.