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Purpose: Bone graft materials and soft tissue allografts are widely used in clinical practice to counteract physiologic postextraction site tridimensional shrinkage. The aim of this study was to test if plasma of argon treatment could have a bioactivation effect on hard and soft tissue scaffolds in clinical usage. Materials and methods: Forty-eight bovine bone matrix and porcine collagen samples were subdivided into two groups (test and control) of 12 samples each. The test group was treated with argon plasma (10 W, 1 bar for 12 minutes), while the control group was left untreated. Immediate cell adhesion and a proliferation assay at 72 hours were performed in the perfusion chamber of a bioreactor. Additionally, micro-CT analysis was performed on the treated and untreated scaffolds, before and after soaking in cell culture medium (four samples). Results: Osteoblasts seeded on plasma-treated bone matrix significantly increased the adhesion level compared with the untreated sample (43,144.3 ± 12,442.9 vs 21,736 ± 77,27.1; P = .0083). However, 3-day proliferation tests could not achieve significant differences between groups (105,715.5 ± 21,751.5 vs 107,108.6 ± 19,343.4; P = .998). No differences were measured on fibroblast adhesion on the collagen matrix in both conditions. Plasma of argon treatment and soaking in cell culture medium did not affect the bone matrix samples. The structure of collagen matrix samples was unaltered after plasma treatment, but became enlarged after soaking. Conclusion: Plasma of argon may be useful to biofunctionalize bone grafts, although benefits seemed to disappear after 3 days. No biologic response was detected on collagen matrix scaffolds. In vivo studies are needed to draw final clinical conclusions.

The aim of the present experiment was to compare the data on new bone formation measured histologically and microtomographically in maxillary sinuses augmented with a xenograft with higher density and higher mineral content compared with the natural bone. The hypothesis was that histomorphometric and micro-computed tomography (microCT) analyses do not yield similar outcomes when a xenograft with higher density and mineral content compared with the natural bone is used. In 18 rabbits, the maxillary sinus was augmented bilaterally using deproteinized bovine bone mineral (DBBM) xenograft granules of either 0.125–1 mm or 1–2 mm of dimensions. The rabbits were euthanized after 2, 4, and 8 weeks of healing. Comparisons were performed between microCT and histological analyses. After 2 weeks of healing, higher contents of bone were found at the histological compared with the microCT analyses in both sinuses, especially in the middle regions of the grafted sinus. Between 2 and 8 weeks of healing, new bone increased of about 21% at the histological analyses while, at the microCT, increased only about 4%. In the same period, the xenograft proportion decreased from 51.6 ± 4.9 to 45.3 ± 3.3% at the histological analyses while, at the microCT, the xenograft appeared to increase in percentages. Histological and microCT analyses yielded different outcomes when a xenograft with higher density and higher mineral content compared with the natural bone was used.

Objective Plasma of argon treatment was demonstrated to increase material surface energy leading to stronger and faster interaction with cells. The aim of the present in vitro study was to test the effect of plasma treatment on different graft materials. Materials and methods Synthetic hydroxyapatite (Mg-HA), biphasic calcium phosphate (BCP), cancellous and cortical xenogeneic bone matrices (CaBM, CoBM) were used representing commonly used classes of bone substitute materials. Fifty serially numbered disks with a 10 mm-diameter from each graft material were randomly divided into two groups: test group (argon plasma treatment) and control group (absence of treatment). Cell morphology (using pre-osteoblastic murine cells) and protein adsorption were analyzed at all samples from both the test and control group. Differences between groups were analyzed using the Mann–Whitney test setting the level of significance at p Results Plasma treatment significantly increased the protein adsorption at all samples. Similarly, plasma treatment significantly increased cell adhesion in all groups. Conclusions Data confirmed that non-atmospheric plasma of argon treatment led to an increase of protein adsorption and cell adhesion in all groups of graft material to a similar extent. Clinical relevance Plasma of argon is able to improve the surface conditions of graft materials.

The palliative care team (PCT), nutrition support team (NST), and department of nutrition in our hospital developed a special soup service for patients with terminal cancer. We evaluated the usefulness of this soup service for improving the mood in patients with advanced digestive cancer with severe anorexia.We retrospectively reviewed the clinical data of 18 patients with advanced cancer originating in digestive organs who received soup service at our institution between 2015 and 2016. Members of the PCT, NST, and a licensed cook visited the bedside of each patient and served them a cup of soup twice a week.Fifteen patients (83%) were able to taste the soup with no adverse events, and 11 (73%) of them enjoyed the taste of the soup. In the five patients who died in our hospital during the service, the time between their last soup intake and death ranged from two to seven days (median three days).Even terminally ill patients suffering from advanced digestive cancer with severe anorexia were able to enjoy the taste of the soup served to them. The establishment of special meal service, such as this soup service, may not only relieve their stress but also support the strength of living and help improve their spiritual quality of life.

Background Although the occupational health field has identified psychosocial factors as risk factors for low back pain that causes disability, the association between disabling low back pain and psychosocial factors has not been examined adequately in Japanese hospital workers. Therefore, this study examined the association between low back pain, which interfered with work, and psychosocial factors in Japanese hospital workers. Method This cross-sectional study was conducted at a hospital in Japan. In total, 280 hospital workers were recruited from various occupational settings. Of these, 203 completed a self-administered questionnaire that included items concerning individual characteristics, severity of low back pain, fear-avoidance beliefs (Fear-Avoidance Beliefs Questionnaire), somatic symptoms (Somatic Symptom Scale-8), psychological distress (K6), workaholism, and work-related psychosocial factors (response rate: 72.5%). Logistic regression was used to explore risk factors associated with disabling low back pain. Results Of the 203 participants who completed questionnaires, 36 (17.7%) reported low back pain that interfered with their work. Multivariate analyses with individual factors and occupations adjusted for showed statistically significant associations between disabling low back pain and fear-avoidance beliefs (adjusted odds ratio [OR]: 2.619, 95% confidence interval [CI]: 1.003–6.538], somatic symptoms (OR: 4.034, 95% CI: 1.819–9.337), and interpersonal stress at work (OR: 2.619, 95% CI: 1.067–6.224). Conclusions Psychosocial factors, such as fear-avoidance beliefs, somatic symptoms, and interpersonal relationships at work, were important risk factors in low back pain that interfered with work in Japanese hospital workers. With respect to occupational health, consideration of psychosocial factors is required to reduce disability related to low back pain.

Streptococcus mutans, a major pathogen of dental caries, is occasionally isolated from the blood of patients with infective endocarditis. Bacterial attachment of exposed collagen tissue in the impaired endothelium is an important step in the onset of infective endocarditis. In our previous studies, some S. mutans strains were shown to possess collagen-binding activities and most of them had an approximately 120-kDa cell-surface collagen-binding protein called Cnm. However, several strains without Cnm proteins show collagen-binding properties. In the present study, another collagen-binding protein, Cbm, was characterized and its coding gene cbm was sequenced in these strains. The amino acid alignment in the putative collagen-binding domain of Cbm was shown to have approximately 80% identity and 90% similarity to the comparable region of Cnm. Cbm-deficient isogenic mutant strains constructed by insertional inactivation of the cbm gene, lacked collagen-binding properties, which were recovered in the complemented mutant. Analyses of a large number of clinical isolates from Japan, Thailand and Finland revealed that cbm-positive strains were present in all of these countries and that cnm-positive and cbm-positive strains were detected in the oral cavity of approximately 10 and 2% of systemically healthy subjects, respectively. In addition, cnm-positive strains were predominantly identified in the serotype f group, whereas cbm-positive strains were frequently detected in serotype k. These results suggest that Cbm as well as Cnm are major cell surface proteins of S. mutans associated with binding to type I collagen and predominantly identified in serotype k strains.

Summary Background Infective endocarditis (IE) is known to be a life-threatening disease and invasive dental procedures are considered to be important factors. Oral amoxicillin (AMPC) is widely used for prophylaxis in patients with heart disorders who are at risk for IE. However, there is only limited information regarding the inhibition of oral bacteria by AMPC. Methods and results Dental plaque specimens were obtained from 120 healthy Japanese adult subjects, then diluted and streaked onto selective medium for oral streptococci. The minimum inhibitory concentration (MIC) of AMPC was evaluated using a macro-dilution method by Clinical Laboratory Standard Institute (2006). Seven strains with an MIC of AMPC of 16 μg/mL or more were isolated from 5 subjects. The bacterial species were confirmed by sequence analysis of 16S rRNA from each strain, which demonstrated that most were Streptococcus sanguinis, followed by Streptococcus oralis. Dental plaque specimens collected from these 5 subjects again after an interval of 2–3 months possessed no strains with an MIC of AMPC of 16 μg/mL or more. Conclusions These findings suggest that strains with a high MIC of AMPC are present in the oral cavities of Japanese adults, though they may be transient rather than inhabitants.

Objective: Cervical or furcal root perforation is a serious clinical problem and one of its treatment modalities is perforation repair with composite resin. However, many cases still progress in inevitable extraction. When primary teeth are affected, early tooth loss can cause problems related to the eruption space for the permanent successors. The aim of the present study was to evaluate a novel clinical treatment method for perforated teeth. Study design: Atelocollagen was applied to perforated furcal and cervical areas of 13 primary teeth in 13 children aged 4-9 years and 8 permanent teeth in 8 adults aged 35-69 years after debridement with an electric knife. Thereafter, the final restorations were performed after confirming good tooth conditions. Clinical evaluations were performed at follow-up examinations at approximately 3-month intervals.Results: None of the treated primary teeth showed any clinical problems throughout the observation period, with eruption of the permanent successors noted in 7 cases. In the permanent teeth, no clinical problems were identified in any of the cases during follow-up periods of 10-60 months. Conclusion: This novel method may enable preservation of perforated primary teeth for a longer duration.

Cerebral gigantism is an overgrowth disorder that occurs from the prenatal stage through childhood and features such clinical symptoms as advanced bone age, macrocephaly, characteristic facial appearance, and learning difficulties. A 4-year 3-month-old girl was referred to our clinic for consultation regarding anterior crossbite and occlusal pain in the molar region. An intraoral examination showed that the mandible was considerably larger than the maxilla. The dental age of the entire dentition estimated from orthopantomogram images was approximately 1 year ahead of chronological age. Cephalometrics analysis demonstrated maxillary protrusion, prominent mandibular protrusion, and vertically severe short face. The size of maxilla was slightly small, whereas that of mandible was above the average. Since height and body weight were above the 97 percentile, the patient was referred to a pediatrician for a general examination prior to dental treatment and diagnosed with suspected cerebral gigantism. As for occlusal pain in the molar region, we considered that it was caused by excessive occlusal pressure. Following application of splinting and several adjustments, the pain gradually disappeared.

The purpose of the current study was to evaluate the molecular mobility of amorphous indomethacin and salicin in the relaxed glassy state based on spin-lattice relaxation times (T(1c)) and to clarify the effects of molecular mobility on their physical stability.Pulverized glassy amorphous indomethacin and salicin samples were completely relaxed, and the T(1c) values were investigated using solid-state (13)C-nuclear magnetic resonance (NMR) at temperatures below the glass transition temperature (T(g)). All NMR spectra were obtained using the T(1c) measurement method combined with variable-amplitude cross-polarization, the Torchia method, and total sideband suppression method.The T(1c) value of amorphous indomethacin indicated that 73% of carbons were in a state of monodispersive relaxation, suggesting that the amorphous state was relatively homogeneous and restricted, particularly in backbone carbons. On the other hand, 92% of carbons of amorphous salicin exhibited both fast and slow biphasic relaxation. Individual structures of the salicin molecules behaved heterogeneously, and thus the entire molecule showed relatively fast local as well as slow mobility.At temperatures below T(g), amorphous salicin had relatively greater molecular mobility than amorphous indomethacin. This difference in the molecular mobility of the two compounds is correlated with their crystallization behavior. Solid-state (13)C NMR provides valuable information on the physical stability of amorphous pharmaceuticals.

Summary The author describes the co-existence of traditional and modem methods of conservation and preservation in Japan. The application of two very different approaches, traditional restoration and mounting and modem conservation and preservation, is shown to be related to the type of material to be treated. Paintings and documents officially designated ‘important cultural property’ are treated by conservators in studios themselves designated as holders of traditional restoration and conservation techniques. Library and archive materials benefit mainly from preventive and mass-treatment measures. Many works of art from small collections are still treated in traditional mounting studios. The development of a new and active type of studio and conservator is described and the process of cross-fertilization between new and old traditions is shown to be beneficial to both.

Oral streptococci are major pathogens of infective endocarditis. Prophylactic antibiotics are commonly given to subjects with certain kinds of heart disorders when invasive dental treatments are performed, with amoxicillin (AMPC) being widely used for this purpose. However, there is little information regarding AMPC-resistant oral streptococci. Here, a total of 344 dental plaque specimens collected from 253 healthy Japanese children, adolescents and young adults (aged 2–22 years) were diluted and streaked onto culture medium containing high-dose AMPC. The MICs for the isolated strains were evaluated using a macrodilution broth method described by the Clinical and Laboratory Standards Institute. Bacterial DNA was extracted from each strain and the entire sequences of the 16S rRNA gene were compared with those in GenBank to identify the species. The results showed that strains with AMPC MICs >16 µg ml−1 were isolated from 18 specimens from 14 patients. Analyses of the 16S rRNA gene sequences of these strains identified them as major oral streptococcal species, including Streptococcus oralis and Streptococcus mitis. These findings indicate that oral streptococci with elevated MICs for AMPC exist in certain small populations of healthy children, and highlight the need for further studies to determine risk factors that lead to the appearance of such strains.

Although several risk factors for stroke have been identified, one-third remain unexplained. Here we show that infection with Streptococcus mutans expressing collagen-binding protein (CBP) is a potential risk factor for haemorrhagic stroke. Infection with serotype k S. mutans, but not a standard strain, aggravates cerebral haemorrhage in mice. Serotype k S. mutans accumulates in the damaged, but not the contralateral hemisphere, indicating an interaction of bacteria with injured blood vessels. The most important factor for high-virulence is expression of CBP, which is a common property of most serotype k strains. The detection frequency of CBP-expressing S. mutans in haemorrhagic stroke patients is significantly higher than in control subjects. Strains isolated from haemorrhagic stroke patients aggravate haemorrhage in a mouse model, indicating that they are haemorrhagic stroke-associated. Administration of recombinant CBP causes aggravation of haemorrhage. Our data suggest that CBP of S. mutans is directly involved in haemorrhagic stroke., The risk factors associated with both ischemic and haemorrhagic stroke are not fully understood. Here a certain strain of the bacteria, Streptococcus mutans, which expresses a collagen-binding protein, is shown to be associated with haemorrhagic stroke in both animal models and human patients.

A case of duodenal varices successfully treated by a systemic obliteration of the varices, which has been employed at the department, is reported with a review of the Japanese literature. A 52-year-old woman was admitted to the hospital because of tarry stool. An upper gastrointestinal endoscopy showed an enlarged and tortuous varices with redness in the second portion of the duodenum. Transileocolic vein portgraphy revealed collateral veins composed of the supperior and inferior pancreaticoduodenal veins. From these findings a diagnosis of duodenal varices was made, and a systemic obliteration of varices which composed of an embolization by coils and endoscopic embolization was performed. After that, endoscopical examination revealed that morphology of the varices was improved but the redness persisted. Endoscopic obliteration was carried out two times. No recurrence of the varices has been observed during the follow up period of two years after the treatment. Duodenal varix is rare and the etiology mainly attributable to portal hypertension. It can cause gastrointestinal bleeding. A systemic obliteration of the collateral veins, which has been employed for esophageal varices at the department, was useful.

The purpose of this study was to analyze the difference in the molecular conformation packed in the crystal lattice between the meta-stable alpha-form and stable gamma-form of indomethacin on the basis of solid-state (13)C NMR spectral patterns. The chemical shifts of each resonance of the alpha-form were distinctly different from the gamma-form. Each carbon nucleus of the gamma-form showed a single signal with no splitting. In contrast, carbon nuclei of the alpha-form showed a complicated set of resonances for each carbon. For some carbons of the alpha-form, four signals assigned to one carbon were observed at 203 K. Two of these four signals were merged between the temperature range from 203 to 343 K without a transformation in the crystal structure. It was found that solid-state (13)C NMR can be a powerful tool to estimate the number of molecular conformations as well as configurational differences in the packing of molecules in a unit cell.

The author proposes a new technique for adhering papers for conservation procedures: micro-dot adhesion. Adhering is one of the key techniques in p"lper conservation. In some cases, waterbased adhesives such as natural starch paste and synthetic methyl cellulose cause trouble with water-sensitive materials. The micro-dot application of paste provides a minimal quantity of the paste. (The percentage amount of paste is roughly estimated from comparison with a graphic designer's screen: it might be 5% or less of the entire surface.) As a result, the paste stays on the surface and hardly penetrates inside. These facts allow water-based paste to be applied to water-sensitive materials for adhering. This is a very useful advantage for practical conservation work. Conventional starch paste, methyl cellulose and hydroxypropyl cellulose in water can be used. Another advantage is that it minimizes drying time, shrinkage and distortion and prevents the adhered papers becoming hard and solid. Furthermore, it offers easier detaching of the adhered papers. Water is not necessary for removing adhered paper, and inserting a thin spatula will be enough to detach the papers. It means that micro-dot adhesion is an easier, reversible method for paper conservation. Application of the paste can be done by various kinds of printing technique such as an offset technique with letterpress and a stencil technique. An ink-blotter has good shape and structure as an applicator for the paste. Instead of blotting paper, a net covers the bottom surface. The net surface of the blotter picks up paste from the table on which the paste has previously been applied flat. For offsetting, the blotter is then rolled on a paper that is to be used for mending. The paste is transferred to the paper from the net in dots and it is ready to use. For rather larger paper, a stencil is useful. A stencil paper having tiny holes, fixed on a frame at its edges, is used for application of the paste just as it is used for silkscreen printing. A larger amount of paste can be applied through the thickness of the stencil paper. The fluffed-up surface of Japanese paper is used for soft and flexible lining. Japanese paper is easily fluffed up by brushing the surface with a hard brush. The paste is applied on top of the fluffed-up fibres by an offset technique. First the paste is applied on a board, and the fluffed-up paper is then gently laid down on the pasted board. One soft brushing is enough to offset the paste to the top of the fibres. The technique is effective in the case of pasting a hinge-paper tip for matting a print. Sometimes an original print can show partial distortion caused by pasting hinge-paper at the corners. The micro-dots do not need much paste, so the pasted part does not contract as much as in the conventional method, because the paste is applied individually in tiny dots and there are many spaces between the dots. The usual, conventional way of pasting a sheet of paper, large or small, has been flat application by brush, even though the consistency of the paste is controlled. To repair a tear in the page of a Japanese book from the eighteenth/nineteenth century, thinly diluted paste is used to prevent the repaired part becoming hard. But thin paste can easily penetrate too much; blotting paper has to be inserted to dry it and to prevent bleeding to the next pages and shrinkage. Drying takes time. The dot-pasted mending paper is first put in a gutter-shaped paper carrier, and the carrier is inserted between the pages. Then the page is lightly pressed and the cmTier is withdrawn, leaving the mending paper. The mending paper does not adhere as strongly as in the conventional method. But such strong adhesion is not needed, because the book is handled carefully in a mu~eum collection and not treated as it was in private, everyday use. Advantages of the micro-dot technique

The hollow cathode HeCd+ laser includes twelve oscillation lines. The oscillation line of 441.6 nm (blue), 533.7 nm and 537.8 nm (green), and 635.5 nm and 636 nm (red) in the visible area can be oscillated concurrently by using wide-band mirrors for a resonator to produce a white light laser. This laser is expected particularly in the image production industry because a single laser tube allows the three primary colors of light to be produced and the green wavelengths are optimum for green emulsion of photographic films. However, it has been difficult to produce the hollow cathode HeCd+ laser of continuous oscillation and high power. We have investigated the high power and output stability of the white light laser for practical purposes. As a result of examining the structure of the hollow cathode as a means for high-power laser, we could realize a high-power HeCd+ white light laser by using a new structure which was an improvement over the conventional flute type. This paper explains the structure of the hollow cathode and shows the dependencies of the output on the Cd vapor pressure, He pressure, input power for the cathode length of 61 or 43 cm, and the noise characteristics for the cathode length of 61 cm.

As a result of study on the NOx formation choracteristics of pre-mixed flames, we have succeeded in developing new low NOx berners. These burners can be used for various kinds of chemical furnaces as gas and/or oil firing burners with a natural draft system.According to the results of test of these burners in the semicommercialized scale test furnace, their NOx emissions were very small, being 30 ppm in propane or naphtha firing, 45 ppm in A heavy oil firing and 90 ppm in C heavy oil firing (of the time of combustion of 5% excess O2)

A hollow cathode He—Cd+ laser simultaneously emits three primary colors. Therefore, a white color laser beam is emitted from this laser. This paper describes the optogalvanic effect and the results of our measurements under the study of stabilization of the white light laser. In the measurement, the colors red, green or blue were monochromatically emitted and the change of the anode voltage was measured in accordance with laser optical power by turning the optical path in the resonator on and off. The optogalvanic signal was noticeable when the color red or blue was emitted. However, almost no effect was observed during emission of the color green. The optogalvanic signal during emission of the color blue depends not only on the optical intensity, but the beam diameter. This indicates that the optogalvanic signal during emission of the color blue is dependent on the change of the cathodic effect. On the other hand, the gain distribution of blue in the bore is presumed to reach the neighborhood of the cathode surface. During emission of red, the optogalvanic signal is proportional to the light intensity, regardless of the beam diameter. It is understood that the optogalvanic effect during red color emission is caused by the change of the He+ population which is distributed at the center of the bore and is the origin of the red color emission.

The aim of this article is to investigate algebraic nature of systems of one-valued mappings of given group into given field and to apply it to the theory of Galois algebras and duality of compact T0-groups. The results obtained in the following are those; factor systems of Galois algebras with finite Galois groups are defined without any restrictions on the orders of Galois groups and the coefficient fields, a necessary and sufficient condition for them to be associated with Galois fields is obtained, dualities of finite groups are obtained very simply without any restrictions for coefficient field of representations, and Tannaka’s duality of compact T0-groups is proved without the use of the compactness of Tannaka representation groups of representations of compact T- groups and the use of Kampen’s theorem.

Let k be an algebraic number field of finite degree or an algebraic function field of dimension 1 with finite constant field and let K/k be a finite, separably Galois extension field. We call an algebraic extension field L, not necessarily Galois nor necessarily of finite degree, of K an everywhere locally abelian extension, denoted in the following as EL-abelian extension, for brevity, of K over k, if and only if for every finite extension L' of K in L and every valuation v of L it holds that the completion field Lv' of L' with reference to v is a composition field of KV and an abelian extension Mv of kv in Lv', where we denote by kv and KV the closures of k and K in Lv', respectively. Let Q be an algebraic closure of K, BK/k the maximum separably EL-abelian extension of K/k in Q, CK/k the maximum separably central extension of K/k in Q (i.e. the maximum extension CK/k which is separably normal over k, contains K, and has the Galois group of CK/k/K in the center of the Galois group of CK/k/k), Ik and IK the groups of the ideles of k and K, Ak and AK the maximum separably abelian extensions of k and K in Q, respectively. Let DK/k=BK/k nCKIk. Then, the norm residue symbol 0Jk in Ak/k is, if restricted into NK/kIK, extensible into a homomorphism UK/k of NK/kIK into the Galois group G(DK/k/K). We shall study in the present article arithmetical meanings of the extensibility. In ?1, we shall define oUK/k precisely, in ?2, study the kernel and obtain a principal genus theorem (Theorem 2), from which will follow easily a certain generalized formulation of some fundamental theorems in the class field theory.1 Combining it with a known property2 of the quotient group of the connected component of the unit element of the idele class group by the natural image of the maximal compact subgroup of the connected component of the unit element of the idele group, we shall obtain, in ?3, our main result (Theorem 8), which concerns total norm residues in the principal idele group of k for K/k, and which is, the author thinks, an idele-theoretic reconstruction of a research of Scholz.3

A new hollow cathode He–Cd+ laser—an improvement of the flute type—was investigated experimentally. Using wideband mirrors, the 194-mW simultaneous oscillation power output was obtained within the visible light range; red lines (635.5,636.0 nm), green lines (533.7,537.8 nm), and a blue line (441.6 nm), at 2-A anode current. Conversion efficiency of 0.032% was obtained. The laser tube is provided with 20 anodes on the upper side at 3-cm intervals and a cathode having an effective activated length of 61 cm. The diameter of the bore is 4 mm. Cadmium reservoirs are provided in the middle of each anode on the lower opposite side. The cathode is made of pure iron. By virtue of close contact between the cathode and the Pyrex glass envelope, the glow is condensed within the cathode bore, resulting in high efficiency. With this construction, sputtered material in the bore may quickly be exhausted out of the bore, keeping the inside of the bore clean; moreover the uniform arrangement of cadmium reservoirs over the whole length of the cathode contributes to high efficiency and stability.